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1: RE: My 6n6p experiments (2.52)
Posted by KurtP on 2007-12-30, 06:53:43 (72.131.105.61)
Agreed. The power amp needs help (or replacement). I am in process of building the power supply for a 300B PP amp. It will use your PP input stage topology, with amorphous Lundahl. Power supply should .......
2: Re: What is the gain of this amp ? (2.52)
Posted by akltam on 2005-10-04, 22:28:59 (202.64.7.15)
I have the impression that you need a gain of about 15-20 for a power amp ?? What do you use this amp for ? Alan .......
3: RE: Which SE amp should I build next? (2.50)
Posted by Waldstein on 2008-09-03, 13:27:57 (209.121.88.140)
Now I am also thinking about building a 45 amp. I was able to talk to Kevin who sells Lundahl. Thanks Kevin! Now I have more information with which to make decisions. Kevin has heard the 6C45p impleme .......
4: RAKK dac direct to head amp (2.39)
Posted by Last-good-name on 2006-12-30, 14:16:34 (72.74.86.138)
Hi, I'm looking for a new DAC to complement my new headphone amp and the RAKK dac looks very promising. What I'm wondering is: knowing the characteristics of said amp, is there any way to optimize the .......
5: WoW !! (2.39)
Posted by Adrianto on 2005-08-23, 20:29:04 (219.83.1.27)
Hi ! Your amp inside looks like VAC reference amps with those Lundahl transformers :-) I wonder how much does the amp weight with those transformers... Please update us with a review of the amp sound .......
6: Its for my PASS X250 amp (2.38)
Posted by fin1bxn@msn.com on 2007-12-20, 19:02:11 (70.21.190.55)
That output impeadance seems high for my amp, but I'm not a technical person and dont know how the circuit might affect the output matching for my amp. My amp is rated at 11K for single ended and 22K .......
7: Upgrade for Cayin A88T integrated amp (2.37)
Posted by Peaman on 2010-01-28, 13:54:00 (78.156.64.97)
I have the above mentioned amp here in London, UK. I'm slightly concerned about power supply in the UK being 240V and the amp being rated at 220V. Does this present a major problem, and would changing .......
8: LL1620 for 845SE amp (2.37)
Posted by vituschan on 2003-02-18, 00:23:44 (202.128.225.3)
Can anyone please advise whether I can use the LL1620 to replace my burnt OPTs of my 845 amp. I saw in the spec sheet of LL1620 that it can only take up to 380V in SE mode. My amp has 1000VDC in B+ an .......
9: Re: Opinions needed for tube amp kit ! (2.35)
Posted by sinewave on 2003-08-09, 20:02:31 (198.81.26.9)
Ever concider making circuit board with the amp line stage kit, PP and SE ? That could could be included with a amp kit and sold seperately. Just a thought. .......
10: KT88 Monoblock amp woulda's (2.35)
Posted by KevinC on 2003-09-05, 15:53:52 (152.163.252.5)
Thanks, Jeff. If we were to buikd this again, we would use an LL1660S/PP interstage. I have used it in a PP300B amp that sounds really exceptional. It just didn't exist when we started the KT88 amp. K .......
11: pre-amp OPT (2.34)
Posted by ofugm on 2004-02-09, 15:58:34 (65.92.109.44)
I have a pre-amp with an output cap. I want to convert this to a balanced output tranny. I want to do this to allow long distance between my pre-amp and amp (40+ feet). The circuit side of the cap has .......
12: Re: K&K phono stage--great kit (2.33)
Posted by Carl on 2003-11-24, 13:40:57 (198.26.74.100)
I use a homebuilt A Loesch phono WE417a with fet, 6gk5 and 5687 into a PP EL84 amp. I use about 3/4 volume. I'm very pleased with it. I would shoot for about 70 db gain depending on the sensitivity of .......
13: LL 1660 as a input transformer (2.32)
Posted by RM on 2005-05-16, 06:21:46 (217.23.194.52)
Anybody use LL1660/18mA as a input transformer (1:2,25 configuration)? I have one pair of them from my ex PP amp and just make my new amp based on John Swenson LTP diff EL84 amp. Thanks. .......
14: 10 PP amp (2.31)
Posted by Jon Lane on 2005-05-22, 10:09:09 (69.109.24.35)
Since I have a few sets of 10's (not 801's, but could get those too) I wonder about a PP 10 amp project. The 10 is a little unconventional as it has both high gain and high plate resistance. The three .......
15: RE: Review of ST70 amp mods on Dagogo? (2.30)
Posted by Bradleycougar on 2015-02-05, 13:54:04 (76.111.41.172)
I found his review and read part 1 and 2 before I purchased my ST70 total amp kit from Kevin. I found his phone number somehow and called him to ask the very question you posed. His answer was that he .......
16: RE: The Last Amp I Am Ever Going To Build. Maybe. (2.29)
Posted by nerdorama on 2009-08-01, 11:11:44 (67.171.0.218)
Hi Kevin, Thanks for the comments. I've never looked on my scope at the full power limits of my amp. I was only thinking of the hard current limit imposed by the CCS. Once one of the tubes in the pair .......
17: which digital amp manufacturers? (2.28)
Posted by ppickard on 2004-04-03, 18:49:18 (24.30.55.150)
Steven - Which digital amp manufacturers are using the input/output trannies? I'd like to take a look at what they're doing. I just picked up the EB-104 and EB-103 Tripath boards, and I'm planning on .......
18: LL1544A BalUn input + line out (2.26)
Posted by Brinkman on 2020-02-13, 17:15:45 (76.126.7.187)
I have single ended tube amp being fed from a balanced line stage. I intend on adding a LL1544A for balanced-to-unbalanced conversion. Since the output transformers on the SE amp are a bit undersiz .......
19: Re: best driver for LL1660/10 in SE amp (2.26)
Posted by pipo on 2003-01-24, 00:45:21 (195.241.224.59)
I have a simple 6n1p=>cap=>EL84 amp, and this is hard to beat. So I will certainly try the 6n1p. I have not done it because I was afraid that the outputimpedance of the tube would be too high for a IT .......
20: New ST-70 Upgrade Kit available (2.26)
Posted by KevinC on 2013-03-11, 09:24:26 (99.178.170.125)
Check out the Power Amplifier page for the latest on this. I have to say that I am really enthusiastic about the "all-in" amplifier that has resulted from revising the original kit. Nothing on the amp .......
21: Want to built a 300B PP amp, Kevin please advise (2.23)
Posted by Louis Sit on 2005-04-02, 23:55:00 (219.134.239.78)
Hi Kevin, I would like to built a 300B PP amp and considering whether Karna (from Lynn Olson) or 300 PP amp from your site. I haven't DIY any tube amp but I did make some SS amps. Therefore, kindly pl .......
22: Re: All Globe Differential Headphone Amp? (2.22)
Posted by AnandR on 2006-03-29, 07:03:00 (192.35.79.70)
Kevin, Cool differential headphone amp design. I always wondered why you never took your 6SN7/2A3 headphone amp design a step forward and make it differential? Anand. .......
23: gain reduducing (step-down) audio transformer? (2.22)
Posted by dado5 on 2003-04-17, 18:26:20 (204.186.214.11)
Howdy, I got a minor problem that I can't seem to resolve. I just built a headphone/pre-amp kit. Problem is the combined gain of both units is too much (25 dB in the pre and 30 dB in the amp.). I have .......
24: RE: PCM1794 + LL1674 & balanced outputs (2.22)
Posted by Lucifix on 2008-08-19, 04:37:25 (86.123.70.158)
... and the last one: .......
25: LL1674 and LL1676 which to buy (2.19)
Posted by limkw on 2004-01-09, 23:18:59 (202.160.21.16)
Hi Kevinc , I would be much appreciated to find out from you the following . The line input transformer LL1674 and LL1676 which is the most suitable to use for the following situation. I have two tub .......
26: "Remote" terminal suggestions to interface with Lundahl transformers? (2.19)
Posted by macm75 on 2012-12-22, 16:43:33 (108.16.206.74)
Hello, I breadboarded a headphone amp that is ready for a box. The amp uses LL1660's in 4.5:1 (load is for triode connected 7788's and headphones are 600ohm DT880's). I'd also like to potentially use .......
27: Re: Kevin, Congrats! (2.18)
Posted by tuneful on 2006-09-30, 13:21:08 (67.42.204.226)
Congratulations on the review, Kevin! I built the mono separates version of this amp last year and can second the reviewer's comments. It's very, very musical, realistic, detailed, and dynamic -- not .......
28: best driver for LL1660/10 in SE amp (2.18)
Posted by pipo on 2003-01-23, 13:31:38 (195.241.251.213)
I have tried a parallel 6sl7 in a KT88 se amp but I am not (enough) impressed. After that I tried a parallel 2C51 (= 6n3p=5670) before the LL1660 in a (6B4G)test amp and that is much giving better res .......
29: RE: Sakuma amp (2.16)
Posted by JoshK on 2015-03-26, 19:52:31 (174.117.103.212)
If its your first time and given your triamp system with hi-sensitivity midrange/top, I'd go for a sakuma type amp with 2a3 all around, or you could copy the Magnequest SETH amp (sorry Kevin for the s .......
30: buzz in Amp (2.16)
Posted by Stuben on 2006-04-01, 14:50:32 (68.170.122.143)
Guys, After changing out an ECC99 for a 6922 as a driver for my IT coupled EL84 pp, the amp is buzzing. This sounds like filament buzz. Before this change, the amp had no buzz. I'm observing good fila .......
31: 6AS7 PP Amp - Richard Sears (2.16)
Posted by JohnP on 2008-03-30, 02:35:56 (222.155.78.8)
Hello, I investigating making the 6AS7 PP amp designed by Richard Sears as published in Audio Express May 2006. I note in the sources list that KandK were contemplating building a kit form of this amp .......
32: Best Lundahl OPT for VTA-120 (2.15)
Posted by Cougar on 2016-10-14, 13:37:55 (68.8.153.82)
I have a VTA-120 power amp it sounds and has good OPT's but I have read the OPT's are the heart of a TUBE amp so I would like to know which of the Lundahl OPT's will be the best replacement to fit on .......
33: Do let us know the result of your amp building !!! (2.15)
Posted by akltam on 2004-02-19, 16:42:50 (202.135.223.109)
I also built that amp but with some modifications. Let us know your results. Rdgs Alan .......
34: Power Transformer for Claus Byrith 8 Watt SE Amp (2.15)
Posted by Ignaz on 2004-06-01, 19:36:26 (128.104.53.162)
Mr. Byrith does not specify a specific power transformer and choke for his 8W SE amp posted on the Lundahl site. Can anyone recommend suitable units for this amp that would not require changing other .......
35: Progress of my 6550 amp (2.14)
Posted by akltam on 2003-11-21, 06:09:14 (203.168.166.42)
I first started with this design http://www.newmilford.com/akltam/6550amp/6550with1660.jpg but the result was not satisfactory at all. It sounds indeed very strange, no treble. Can't get it right. The .......
36: Re: Kevin K - compare 300B PP and KT88PP? (2.14)
Posted by KevinC on 2004-05-26, 11:39:01 (205.188.116.9)
The difference between the 300B and KT88 P-P amps is one of resolution vs. guts. The 300B amps reveal more inner detail, ambience and nuance, but just don't have the hard-driving impact that the triod .......
37: RE: 12B4A Line stage with K&K CCS (2.13)
Posted by Barossi on 2009-02-23, 08:19:13 (132.189.76.18)
Hi Kevin, you probably have a new mail :-) KR Hauke .......
38: RE: Which SE amp should I build next? (2.13)
Posted by Waldstein on 2008-09-03, 10:59:36 (209.121.88.140)
Thanks for you input! I am wondering whether you built the same 6c45p that I am considering. The other low power amp that I built also had low watts: ca. 2W and seemed just fine for loudness (I can't .......
39: Re: Lundahl for sets? (2.12)
Posted by David Gill on 2005-05-25, 09:25:39 (70.19.215.16)
I've built a single ended headphone amp and a single ended 211 amp using the Lundahl outputs and have been vary happy. The 211 amp has a great natural and open sound that fits in well with the other w .......
40: Lundahl 1620 80mA OPT's (2.11)
Posted by kid squid on 2008-02-04, 03:32:05 (212.139.102.166)
Hiya Chaps, Just got hold of a pair of Lundahl 1620 / 80mA SE OPT's, at a local audio fair, and I'm wondering, if any of you kind chaps, have any schematics for an amp, that will allow me to use the b .......
41: RE: Question about LL1544A as phase splitter (2.11)
Posted by DAK on 2016-06-30, 12:54:38 (141.239.172.61)
Hi, Kev, I am planning to use my preamp to drive the amp it is a tubed preamp with 6sn7 tubes. I was originally, going to use the 1:1 config for 6sn7 driver tube on the amp. But now i am going to use .......
42: Re: KT88 Monoblock amp picture (2.11)
Posted by akltam on 2003-09-06, 08:16:03 (203.168.166.42)
Kelvin, Please show me the inside of this amp. I don't see the lundahl around. It is so professional. Thanks. Alan .......
43: RE: Driver transformer for PSE KT90 amp (2.10)
Posted by KevinC on 2012-12-27, 05:53:59 (99.178.170.125)
Whether you build monoblocks or a stereo amp you need one LL1692A or one LL1660 per channel. .......
44: Joe's Original Amp Pics (2.10)
Posted by GlassBottles on 2005-06-23, 10:41:06 (207.69.5.95)
Rick, Nice job on the chassis. I wish I had access to some CAD machines as I had to do all the metalwork by hand !! The metalwork took the majority of time I have invested in building the amps. Once t .......
45: No one actually build an amp this way ? (2.08)
Posted by kupfer_m on 2009-03-31, 08:41:42 (81.83.245.186)
Is there anyone who has build an PP-amp with this SE trannie ? Greetz, K. .......
46: new mic amp? (2.08)
Posted by james@boyd.org on 2007-11-05, 14:46:55 (87.113.74.154)
Any news on the new mic amp? I really need to build some soon! op.9 .......
47: Questions on K&K PP front-end design (2.07)
Posted by Francois G on 2004-06-16, 11:07:40 (129.229.32.142)
I'm contemplating my new power amp and is interested in the K&K design. I have a couple of questions: 1) I believe the LL 1667 has two coils. Is the LL1667/5 ma plate chokes shown in the schematic one .......
48: Re: K&K phono kit question..... (2.06)
Posted by b.ball on 2006-05-09, 11:43:23 (209.53.175.250)
Hi, Thanks for your feedback. I really enjoy the kit. I use it with S&B step up. I recently have completed a 300b amp, I really like what BG cap does on my amp, that why I am itched to try them out on .......
49: Is K&K out of business? (2.06)
Posted by KBlum on 2021-03-04, 09:41:17 (83.76.217.95)
Is K&K out of business? After two weeks no answer of email order question. Kurt .......
50: Re: Do let us know the result of your amp building !!! (2.06)
Posted by martin poulin on 2004-02-26, 11:34:16 (66.38.227.145)
HI I will post my result. I don`t follow do a 100% clone. I will use this amp from 0-170Hz Only. So i choose Svetlana 6550 instead of kt88. (tetrode, pseudo-triode switcheable) My driver is the WE417A .......
51: Re: DAC with Lundahl LL7902 transformer coupling (2.06)
Posted by hkchuengs@netvigator.com on 2004-01-03, 05:21:17 (218.102.207.199)
I have done that in Oct 2003. I keep both the RCA output and the trans output stage using LL7902. The sound of the two are quite close and I cannot tell which is better as it is a matter of taste. Pow .......
52: 6C45P Driver for IT coupled 2a3 (2.06)
Posted by KevinC on 2006-05-12, 15:13:23 (205.188.116.66)
Well, I tried it in a 2 stage IT coupled PP 300B amp and the amp might as well have been a 70s transistor amp for the sound that it made. I tried various operating points and finally abandoned the que .......
53: How Do You Like Your Amp's Sound? (2.05)
Posted by MikeT on 2004-09-14, 15:00:47 (192.160.6.253)
How would you compare it to capacitor coupled designs, and designs that use diff amp phase splitters? .......
54: Re: any amorphous core tr. for 1:8 ratio and balanced input? (2.05)
Posted by MaciekP on 2003-09-30, 05:18:02 (198.152.150.69)
thanks, I have attached the connection schematics. I'm not sure how to use the link you gave me to optimize the connection between preamp and power amp. I didn't connect the LL1674 input transformer t .......
55: Re: Opinions needed for tube amp kit ! (2.04)
Posted by sinewave on 2003-08-09, 19:22:42 (198.81.26.9)
How about offering amp line stage kit, all assembled on a circuit board ? .......
56: 1674 as input trans to amp (2.03)
Posted by 45drive45 on 2003-03-03, 21:58:31 (203.116.61.131)
Hi, I believe I can use the 1674 as step up input trans for my Power amp. When using input trans, I suppose I have to be careful on the output impedance of my preamp. What would be the impedance of th .......
57: Re: Are you determined to build this amp? (2.02)
Posted by beaufortralph on 2004-08-23, 13:10:05 (68.115.125.165)
Thanks for the input. I talked to Kevin this afternoon and he makes a good case for something other than the amp I was considering. I am going to look into a modification of the KT88 you refered to in .......
58: Minimalist Active-crossover Pre-amp (2.02)
Posted by akltam on 2008-12-12, 01:04:34 (222.166.160.146)
This circuit is probably considered as the minimalist pre-amp. I have extended this idea to become a minimalist active crossover and pre-amp. Thanks to the number of of secondaries of the LL1660/1671 .......
59: Re: pre-amp OPT (2.02)
Posted by ofugm on 2004-02-11, 06:08:09 (65.94.237.219)
My pre-amp is a grounded grid by transcendent sound. Which I find to be excellant sounding. I built it as a kit. .......
60: Connecting RAKK output to Mood Indigo in (2.02)
Posted by Francois G on 2004-08-03, 10:54:50 (129.229.32.142)
Thanks for the information on the RAKK. It seems like a "must have" item to go with the Mood Indigo line amp I'm currently planning. Is it feasible to utilize the LL1674 on the input of the Mood Indig .......
61: RE: Single stage DHT headphone amp (2.00)
Posted by hvbias on 2014-09-21, 18:14:22 (66.30.103.154)
Kevin, have you tried the LL1930 for headphone use? I think at this point I'll build a spud amp using more conventional tubes that are normally used. .......
62: it will be a SET amp. (2.00)
Posted by Cougar on 2014-07-13, 15:55:27 (68.8.154.37)
Hi Kevin, It will be a SET amp running 1kVdc on the plates of the 845 tube. Would these need to be totally enclosed due to this high of voltage being used? Thank You for all the help/info! ::: TOPIC:: .......
63: Re: Are you determined to build this amp? (1.99)
Posted by beaufortralph on 2004-08-23, 05:48:12 (69.68.73.75)
I am determined to build an amp. (or 2) I do not have any parts yet and will appriciate any input. .......
64: Re: Power amp for ST 70 clone (1.99)
Posted by gjo on 2004-03-04, 07:26:04 (203.195.212.174)
Yes, you're right, I meant power or mains transformer, wrote power amp by error. Thanks for the info George .......
65: RE: Mounting CCS (1.98)
Posted by JKT on 2010-12-21, 14:05:44 (69.29.92.89)
You can see how I mounted two pair of CCSs in my 2A3 amp here: http://www.raleighaudio.com/tracy.htm No shock mounting, but as transparent as the amp is now, I think that would be over-kill. ::: TOPIC .......
66: RE: Is K&K out of business? (1.98)
Posted by KBlum on 2021-03-08, 12:13:19 (83.76.217.95)
Strange, no answer from Kevin and no answer from Lundahl of the question: whats the problem with Kevin, until now. .......
67: A B listeningtest (a bit long) (1.98)
Posted by Goofey on 2003-05-18, 08:34:01 (80.164.13.47)
Hi Built 2 2A3 stereoamps last evening , 6SL7 driver in both capcoupled. Amp A with LL1620 , konventional SE. Amp B with 1668/60mA platechoke and 1664 PPZ parafeedcoupled with an homemade 4.83uF. Powe .......
68: Opinions needed for tube amp kit ! (1.97)
Posted by KevinC on 2003-08-09, 09:35:35 (205.188.208.9)
Funny you should ask. I have a design for a relatively simple, but good sounding, P-P amp that is IT coupled. I am strongly considering offering this as a kit. A couple of questions remain to be resol .......
69: Re: Thanks (1.97)
Posted by Scholl on 2005-03-09, 14:25:37 (68.60.233.193)
I think the 1660S is simpler than parafeed. Lundahl did the hard work for you already. The circuits are simple requiring as little as 10 parts per channel not counting the power supply that's as simpl .......
70: Re: transformer coupling to 6L6 pp (1.96)
Posted by razorsharpedge on 2005-12-20, 06:24:59 (64.235.97.35)
Thanks for the info Kevin. It does, however, raise alot more questions. (did I mention that I'm new to this?) How does a booster amp differ from a power amp, and how did that 4 ohm resistor tell you? .......
71: Questions on LL1544A (1.96)
Posted by akltam on 2014-06-01, 02:26:15 (222.166.2.28)
Hi Kevin, What do I do with the 'Centre Tap' under the connection L4B as shown in the data sheet of L1544a ? Do I connect it (the 'Centretap') to the ground of the amp ? Here is my intended use of .......
72: Re: Lundahl trannys for LA-2A (1.95)
Posted by sinewave on 2003-08-06, 18:31:47 (198.81.26.9)
I was planning using K&K PP amp input circuit in my amp prodject. My question is what tube can be subsituted for the 6BX7? I have tried finding a source for this tube, but have had no luck. ::: TOPIC: .......
73: Re: RAKK dac direct to head amp (1.95)
Posted by KevinC on 2006-12-30, 15:57:12 (70.144.163.245)
What kind of design is the headphone amp? Unbalanced input? Volume control at the input? Kevin Carter K&K Audio www.kandkaudio.com .......
74: RE: Compact Current Source Kit (1.95)
Posted by tuneful on 2009-09-24, 14:20:22 (75.161.96.26)
Here is the schematic of his amp as posted on the SET asylum: .......
75: RE: PP 300B direct coupled input/driver as a PP amp? (1.95)
Posted by nerdorama on 2018-01-13, 10:24:00 (24.16.106.44)
I will likely do something that includes ideas from both Lynn Olson's Karna Kay and Kevin's amp on his blog post. John .......
76: Power amp for ST 70 clone (1.95)
Posted by gjo on 2004-03-04, 01:03:42 (164.164.88.26)
Kevin Which power amp suitable for 220/230 VAC input power would you recommend form your range for this application? Thanks .......
77: Phase splitting input transformer for PP RH amp (1.94)
Posted by DAK on 2016-05-23, 17:11:02 (141.239.172.61)
Hi, I am contemplating this design to create a PP RH style el34 amp using EICO HF87 output transformers. The input would be split by the IT and then each signal would be driven by its own SE RH amp. I .......
78: Think of it another way (1.94)
Posted by Caucasian Blackplate on 2007-11-28, 13:03:45 (199.237.188.196)
I wouldn't use wire that spendy for wiring up filaments or anything, but how many feet of wire do otherwise need in an amp? I would wager that 4-5 feet for a stereo amp is more than sufficient unless .......
79: RE: Sakuma amp (1.94)
Posted by JK-Tri amps on 2015-03-25, 21:34:55 (171.101.39.161)
I like the concept of Sakuma that he use a 845 as amplify tube and (2) 845 as out put tube as well. Perhaps is it possible to do Tri-amps or bi-amps on KT150 and adjust any necessary transformer & .......
80: parafeed pre-amp (1.93)
Posted by DWong on 2003-03-25, 23:12:12 (202.128.225.3)
I am planning to try the Euridice pre-amp using 6S45P with parafeed configuration. Would 1674 be suitable for this application. What model of plate loading coke should be used? .......
81: Re: Your platechoke loaded KT88 amp (1.93)
Posted by akltam on 2003-09-20, 07:54:07 (203.168.166.42)
Kelvin, There seems to be very little information or very few has tried plate choke and be able to compare the difference. I believe plate choke pre-amp may be easier to try. If you do try this, ple .......
82: which amp to build? (1.93)
Posted by Freddy G on 2004-09-21, 19:15:52 (206.47.151.43)
Hi, I would like to build a stereo (or two monoblock) tube amp. I have never owned a hi-fi set that I really liked, and seeing as how my Luxman receiver is dying I would like to start my journey with .......
83: My new amp with 2 pairs of 6550 (1.93)
Posted by akltam on 2005-03-17, 05:50:02 (222.166.160.166)
http://akltam.50megs.com/newamppic/DSC_0001_a.jpg http://akltam.50megs.com/newamppic/DSC_0005_a.jpg (without the cover on the tx). http://akltam.50megs.com/newamppic/DSC_0007_a.jpg The gain of this am .......
84: How to repair my pre-amp? (1.93)
Posted by jfutchco@hotmail.com on 2006-05-15, 08:26:57 (69.129.204.192)
I am not sure if this is the right forum to be posting at, but this is where I wound up after doing some searching... I am looking to repair my instrument pre-amp, a Raven Labs PMB-II instrument blend .......
85: Re: Driving EL84's PP (1.92)
Posted by Joel Tunnah on 2005-10-07, 06:47:29 (208.255.103.99)
LL1676 input (1:1), ECC99 driver, LL1660S/PP interstage seems to be a good combination. See Lynn Olson's "Amity" amp. That amp has a very poor input sensitivity however, and the ECC99 has a very high .......
86: Fully coupled KT88 amp questions (1.92)
Posted by Frihed89 on 2009-11-18, 02:56:28 (87.53.108.34)
1. Has anyone ever built this amp for the 6550A? 2. As monoblocks? 3. With tube rectification? 4. Was/is hum a problem? 5. What did the parts cost - ball park? 6. Did you look into (and/or buy) other .......
87: Re: KT88 Monoblock amp picture (1.91)
Posted by akltam on 2003-09-06, 08:33:48 (203.168.166.42)
Kelvin, You have post before that you are considering having a PCB for a tube power amp. Will you be considering doing this one as the driver PCB. You have this for this 2 pairs, also for your 300B. .......
88: RE: best output transformers for gm70PP (1.91)
Posted by jota on 2011-10-10, 12:25:03 (79.46.226.218)
Hi, I want to build this amp: All PP, 6SN7 RC coupled , 45 LC coupled , GM70 is essential to DC heaters? karna amp is all AC filament... you can publish your schematics? best regards .......
89: RE: D3A Amity Style Amp (1.91)
Posted by KevinC on 2015-05-05, 06:59:43 (99.178.170.125)
Yes, he tested a couple of the new series of products that are described in my website blog. Here's a picture of the power supply board that he used. It was originally developed for the SE 6C33C, b .......
90: mono from stereo (1.91)
Posted by nyatt on 2010-01-09, 12:39:06 (99.32.114.177)
Kevin, I have a friend who wants to add a Mono center for his stereo. Solid state preamp and amp. Is there a transformer solution that will create a mono signal by adding left and right, but still all .......
91: RE: PCM1794 + LL1674 & balanced outputs (1.91)
Posted by Lucifix on 2008-08-19, 04:29:04 (86.123.70.158)
... this is another image with one possible connection between PCM1794 and LL1674: .......
92: Transformer for Foreplay pre-amp (1.91)
Posted by Alvinltc on 2003-06-11, 02:11:50 (203.143.133.7)
Hi, What will be the appropriate model to replace the standard transformer in the Foreplay pre-amp. My mains are 220-240V. Thanks! .......
93: PP amp rectifier diodes (1.90)
Posted by Uncle Clyde on 2005-03-23, 11:49:34 (166.61.234.85)
Kevin, What are those rectifier diodes (values and brand) you use in your push-pull kt88 amp? Clyde .......
94: Re: Are you determined to build this amp? (1.90)
Posted by SteveBrown on 2004-08-24, 08:27:57 (155.188.255.3)
Also check out the PP47 on Gary Pimm's site: http://home.pacifier.com/~gpimm/schematics.htm I built this amp (Rev 8 of it) using a bit different power supply and EL34's for about 5 watts output. This .......
95: Re: My new amp with 2 pairs of 6550 (1.89)
Posted by akltam on 2005-03-17, 15:35:51 (61.10.7.52)
In fact, I have to say thank you to you, Kelvin, Your schematics has given me the insight and path to this project. For the gain, it is a compromise. 1. I am working on the parts that I have got 2. .......
96: Schematic and details of PP ESL amp... (1.89)
Posted by Bas Horneman on 2003-08-11, 15:53:50 (62.59.101.119)
Esl amp project> My (very hypothetical) ESL amp (with 1:4 step up transformer) The purpose of this amp is to drive an wire stator ESL Details of the ESL Dimensions : 13cm wide * 100cm high .......
97: Your platechoke loaded KT88 amp (1.89)
Posted by akltam on 2003-09-19, 05:33:50 (203.168.166.42)
Kelvin, Can you describe the use of plate choke in your KT88 amp ? What is the difference sonically if I use resistor instead ? What is the advantages in using plate choke? Thanks. Alan .......
98: RE: 2A3 Differential Parafeed Advice Wanted! (1.89)
Posted by nerdorama on 2008-06-01, 10:31:22 (76.104.204.83)
Hi NigelJB, I've made an amp similar in some ways to the one you have planned. I also use an LL1660S. I really love the sound of the differential PP amp. Give it a try. Regards, John De gustibus no .......
99: need parafeed output for 801A with C4S active load (1.88)
Posted by DMY on 2003-02-09, 18:12:35 (12.246.170.78)
Iāve been playing with a line amp using 801A DHT, active c4s plate load and parafeed with UTC 20K/600 Ohms output transformers on loan from a friend. I am running the 801A with 175V B+ at 20 ma. Afte .......
100: RE: Which SE amp should I build next? (1.88)
Posted by gluca on 2008-09-03, 07:33:00 (87.7.95.94)
I built a 6C45p amp a while ago and liked it. Do not expect much more than 1.5W so keep in mind you would prefer to use a 100+dB speakers. Anyway I strongly suggest to use a fixed bias at the grid (ba .......
101: Re: Comments on 12BH7A-IT-2A3 amp? (1.88)
Posted by BAU on 2004-11-17, 11:37:38 (216.6.171.177)
HELLO KEVIN & DIY EXPERT Please give me some comments I still work on it before upgrade to the good parts I connect the CD direct to it [2v- 300ohm] Do I need the pr-amp ? THA .......
102: KT88 PP Mono for Corner Horn! (1.88)
Posted by haukito on 2007-05-06, 09:31:43 (90.187.143.49)
Hi, i would like to build a mono KT88 PP amp for my active system. I would like to use this amp for my corner horns Therefore i am using an active crossover. Will this amp work: http://www.audiodesign .......
103: RE: Which SE amp should I build next? (1.87)
Posted by Jim Womble on 2008-09-03, 08:31:48 (70.90.144.126)
The hammond transformer is a good value for the money, however it will lack low bass and treble extrension compared to a lundahl. I posted below on a partial feedback el84 design using a lundahl 5.5k: .......
104: RE: LL7905 in spud amp (1.87)
Posted by Stephen R on 2008-10-26, 07:47:42 (80.84.161.228)
AFAIK, A spud amp is a "single tuber". Tuber = potato = spud cheers, Stephen .......
105: Recommendation for an balanced input tranny for a power amp, (1.87)
Posted by billwjr on 2004-03-30, 18:23:09 (67.74.209.45)
100K input impedence on the amp, pre can drive down to a 4K load, balanced. Thanx, this thing won't do PDF files for the specs, I'll have to try and surf from work..... .......
106: RE: 4P1L as PP driver (1.87)
Posted by andy evans on 2015-10-26, 10:43:27 (78.144.75.211)
Works fine. A DIY pal made an amp PP balanced right through, 26>4P1L>6C4C. Very nice sound. He used a tube as a current sink under the diff pair, and direct coupled the 26s. LL1660/PP into the finals. .......
107: Line Level Filter w/Tfr Input Help? (1.87)
Posted by SteveBrown on 2004-06-21, 11:54:19 (155.188.255.4)
Can someone shed some light on this... I would like to put a line level HP filter in front of my power amp, which uses an LL1676 as a SE to PP input transformer. The LL1676 goes directly to the grid o .......
108: Which Output Transformer ? (1.86)
Posted by akltam on 2003-09-05, 01:33:57 (202.135.65.77)
I am planning to build a tube power amp. The amp will be push pull and triode configuration using EL34 or 6550, 2 pairs per channel. Which Lundahl and which config should I use ? I am planning to use .......
109: K&K SE phono balanced output drive capability (1.85)
Posted by Ole on 2005-01-17, 03:25:24 (193.90.168.118)
Hi! I am considering ordering the K&K SE Parallel Feed Phono Preamplifier and have a question about the balanced output. My TT and current phono stage is located about 7 meters away from my amp and I .......
110: LL1680 vs LL1689AM with Raven Pre-Amp (1.85)
Posted by Ironmonger on 2005-04-25, 07:21:19 (83.77.45.208)
Hi Everyone, I'm new to the K&K Forum so, Hello! My first question! Has anyone tried using the new LL1689AM with Lynn's Raven Pre-Amp? Both the 1680 and 1689 appear to have very similar specs??? Any t .......
111: RE: Thomas (1.85)
Posted by Thomas Mayer on 2010-05-13, 12:16:46 (93.218.21.187)
Hi Gianluca, I guess the transformer and a detailed datasheet will be available probably within a month or so. I have not measured the primary L yet. In my 801A amp I get a -3dB roll off around 15-16H .......
112: Line Split Out with a 1544a? (1.85)
Posted by CScottG on 2005-01-30, 21:45:59 (70.185.0.236)
I'm interested in doing a stepped (ladder-type) attenuator with a line out split to the amp (and for output to a sub plate amp). Input to the attenuator will be from a CD player. The plate amp will ha .......
113: Flexibility ? (1.85)
Posted by akltam on 2004-01-10, 18:46:04 (203.168.166.42)
There are always numerous possibilities. Even the same circuit, you can try different tubes, different current setting, even slight change of topologies. I have tried at least 3 topologies of this am .......
114: Re: K&K pentode amp design questions (1.85)
Posted by KevinC on 2004-12-11, 10:48:51 (205.188.116.7)
The power will turn out to be around 50w/ch, THD+ noise less than 1% up to 40 watts, and the gain is about 35dB with the interstage wired for about 1:1. If youu need less gain (6dB less), then you can .......
115: RE: New K&K ST70 power transformer question (1.84)
Posted by Brinkman on 2012-12-31, 18:53:24 (98.248.183.78)
Kevin, The updated boards are on the way too? Great news. Three quick questions about the new PCB configuration: How tall are those heatsinks in the middle and how much space is reserved on the new PC .......
116: LL1660 and LL1540 input connected and... HUM (1.84)
Posted by Risky So on 2014-11-20, 20:29:28 (203.210.6.57)
Hi I use LL1660 as single end of pre-amplifier output in balance XLR connection, config in Alt Q wiring. I use it connect to Maclntosh power amp , use a an a year, the sound and respond perfect.. .......
117: Re: My new amp with 2 pairs of 6550 (1.84)
Posted by divo on 2005-03-17, 08:09:14 (209.29.50.252)
Nice work, Alan! How long did it take you to figure out the layout for such a clean interconnection? Is this your first amp project? I heve received parts to start a 300B PP project myself, awaiting c .......
118: RE: stereo 45 single-ended tube amp with LL2766 output transformer (1.84)
Posted by beeah on 2018-08-14, 11:29:48 (98.159.211.50)
Hi Kevin, Are the LL2766 available for sale? I'm in the beginning stages of sourcing parts for my fourth 45 SE amp, and these are very appealing - especially given Johnny's measurements. Cheers, Joe : .......
119: Thanks (1.84)
Posted by dhieber on 2005-03-09, 12:12:04 (138.87.223.187)
Thanks. I'm about ready to take the plunge and order the 1660S. I have to admit, though, that I find the simplicity of the autoformer approach attractive. I've heard Bean Counter's 6B4APP amp (based o .......
120: Kevin - 300B PP? (1.84)
Posted by mgreene on 2004-06-17, 08:25:09 (130.199.3.3)
Hi Kevin, Has anyone built the 300B parallel PP amp (4 X 300B per side) that you designed? I am trying to decide on my next (and hopefully final) amp project. Whats the best time to phone you re an or .......
121: Re: 1676 grounding (1.83)
Posted by Jim Womble on 2006-01-16, 13:41:20 (64.139.91.66)
My linestage and amp both have the jacks grounded. It may be difficult to lift the ground on the amp due to its being soldered to the ground buss. Presently, there is no hum due to ground loop. Jim :: .......
122: Re: gain reducing (step-down) audio transformer? (1.83)
Posted by dado5 on 2003-04-17, 20:10:16 (204.186.210.83)
Thanks for the quick reply, Kevin! Actually, 12 dB is what Mark O'Brien (Rogue Audio) based his 300K-100K divider recommendation on. I was surprised at the sonic impact this had. It seemed to slow the .......
123: RE: 50 ohm load for 1689? (1.83)
Posted by Charlie G on 2008-02-16, 13:56:13 (75.121.141.226)
The transformer will be driven by a current source so if the impedance rises drastically at any point the amp will clip. The amp is flat to >1Mhz so unless I slow it down on purpose I need to make sur .......
124: Re: My new amp with 2 pairs of 6550 (1.83)
Posted by akltam on 2005-03-17, 18:31:05 (63.137.52.3)
Thanks. It does take a lot of time. This is my first tube DIY power amp project from 'scratch'. But I have fully rebuilt another tube power amp before and thus accumulate some experiences to arrange t .......
125: Re: Lundahl OPT for AVVT DHT tube? (1.83)
Posted by KevinC on 2002-10-28, 06:35:04 (152.163.188.5)
There is a special order version of the LL1660 (LL1660/30mA) that will allow you to run that tube with 30mA of standing current and get a 4.5: 1 stepdown in line amp use, resulting in a gain of about .......
126: RE: PSE KT88 amp Schematic needed (1.82)
Posted by yoa on 2013-07-22, 02:25:53 (124.120.66.122)
PSE KT88 amp Schematic needed .......
127: RE: Transformer output stage for Cambridge Audio DacMagic (1.82)
Posted by KevinC on 2010-10-25, 16:53:24 (99.178.170.125)
What you want to do will work fine, but you will have to reverse the polarity of one set of LL1527XL coils to make the signal add instead of subtract. The op amp circuit does the addition in the final .......
128: RE: Phase splitting input transformer for PP RH amp (1.82)
Posted by DAK on 2016-05-24, 10:48:41 (141.239.172.61)
Ok, thanx Kev. One of my concerns is how to mount the units in my amp . Do you have any instructions or photos showing that? The chassis will have about 1 3/4" in depth to work with. I am also conside .......
129: 1544a as phase splitter (1.82)
Posted by Francois G on 2004-05-18, 13:53:20 (129.229.32.142)
I noticed that Mr. Davenport (in his line amp) as well as Kevin (in his power amps) seem to prefer the 1674/1676 in phase splitter duty. Could you explain the reasoning? Could the 1544a be used instea .......
130: Question about LL1544A as phase splitter (1.82)
Posted by DAK on 2016-06-29, 16:26:13 (141.239.172.61)
I am just about ready to install these and just had a question or 2. My use of this unit is for phase splitting to a KT88 PP amp. In the 1:1 configuration there is no gain in the signal. If i use 1 : .......
131: Correction (1.82)
Posted by rwalton on 2004-01-09, 13:19:57 (216.140.123.24)
Hello again, I now realize you said Raven II and not Aurora. My comments were based on the Aurora amp, not the Raven II. Obviously, the Raven isn't nearly as complex (or costly) as the Aurora amp. Sor .......
132: Transformer Selection for F2a Amp (1.82)
Posted by EvilMose on 2011-04-20, 16:15:44 (69.88.81.51)
Kevin, I plan on building an amp around the Siemens F2a. ~8w output and requires a 5k OT, which would seem to call for an LL1663, but the 70ma current draw concerns me. Will the 1663 have adequate ind .......
133: PP output transformers (1.82)
Posted by John Swenson on 2004-09-03, 14:55:35 (147.145.40.43)
My BDT power amp is up and running using cheap Hammond Iron, I would like to upgrade it to something really good. The Lundahl ITs are perfect for this, but I need some help with the OPTs. This design .......
134: RE: Tube Tape Head Pre Amp (1.81)
Posted by Music Man Bob on 2013-03-20, 06:06:54 (72.152.155.199)
Good morning Mr. Kevin Carter, Thank you so much for responding sir. We have developed a tube tape head pre amp based on a phono pre amp that is very good. We used (2) 12AX7's in the early stage wi .......
135: Re: high output transformer make noise? (1.81)
Posted by dongchen_han on 2006-12-22, 11:17:50 (216.218.63.64)
Hi thanks for the fast reply, the transformer is pretty big, I tried to move away the amp at least 3-4 meter, it still does the noise, only when I touch the rca input with finger or plug a source. I t .......
136: Tube Tape Head Pre Amp (1.81)
Posted by Music Man Bob on 2013-03-19, 21:21:23 (72.152.155.199)
Good evening all, I want to add a Transformer to my tube tape head pre amp. The impedance of the playback tape head is 30 ohms which is rather low. Presently, the tech who is building the pre amp aske .......
137: RE: Step Down input or Interstage transformer?? (1.80)
Posted by Ed Sawyer on 2012-01-24, 13:49:06 (132.177.211.86)
Why not just build it as a 2-stage amp instead of 3-stage? Seems silly to step down due to too much gain, yet have a 3-stage amp. 2-stage w/o step-down seems like it would solve both problems and be l .......
138: Single-ended to Balanced conversion via xfmr? (1.80)
Posted by krikor on 2006-02-15, 12:02:01 (207.148.215.182)
I'm not all that well-versed when it comes to transformers, so maybe someone here can tell me if a Lundahl will do what I need in my multi-channel system. My rear channel amp (PS Audio HCA-2) has 24db .......
139: SUT Used With A Tube Tape Head Pre Amp? (1.80)
Posted by Music Man Bob on 2013-03-23, 13:00:47 (72.152.155.199)
Has anyone developed a tube tape head pre amp using an SUT to boost the low output from the reel to reel tape head? The tape head on my Tascam 42B reel to reel is about 30 ohm. I am running cables str .......
140: How do I calculate the amount of current an amp can deliver through a specific OPT? (1.80)
Posted by Frihed89 on 2010-09-10, 23:46:46 (94.18.144.4)
I have a magnetic planar headphone amp that is 91dB sensitive an impedance of 50 ohms that are said to be "current hungry". (I haven't been able to get any other information). I want to build a dedic .......
141: RE: Output Transformers for 845 tubes. (1.80)
Posted by KevinC on 2014-07-13, 14:09:11 (99.178.170.125)
Lundahl outputs will all handle that kind of voltage without a problem. Depending on whether you are planning a push-pull amp (LL9202/PP) or a SE amp (LL1691/80mA) there is a transformer for you in th .......
142: Can I use a LL1676 for a amp first gain stage? (1.79)
Posted by Mike B. on 2020-02-18, 08:13:07 (76.115.149.156)
I built a DIY MOFO single stage class A amp last year. It requires a very high level preamp signal to play at listening levels. I own a pair of LL1676 transformers and wonder if I could use them as a .......
143: RE: WAF direct coupled integrated Push Pull amplifier (1.79)
Posted by KevinC on 2014-02-19, 05:29:17 (99.178.170.125)
I can see why your wife would prefer the first one over the second. Not too unreasonable... Seriously, I like very much the fact that the finished amp looks so good, but has the tubes mounted separate .......
144: RE: 12AU7 differential IT (1.79)
Posted by nerdorama on 2008-06-14, 09:48:00 (71.231.126.72)
Hi Paul, This sounds quite close to my amp driver stage. LL1660S driven by PP 6BX7 or 6BL7 with CCS on the cathodes. I've also plugged in 6SN7's before and they work quite well also, but don't seem to .......
145: Pictures of My ST-70 (1.78)
Posted by seanzozo on 2012-01-16, 15:32:39 (76.183.14.227)
Finished a K&K basic ST-70 about a month ago. I'm using it in an actively crossed open baffle, fullrange + woofer setup. The K&K drives the fullrange and a pair of lightly modified MK-IV's drive the w .......
146: CCS and IT advice (1.78)
Posted by JC951t on 2008-01-20, 07:47:41 (202.156.14.42)
Hi Kevin, I'm writing in to seek for your advice on the following. 1. How does CCS sound compared to Choke loading ? 2. I'm interested in trying out IT in my PSE 300B but I'm a little confuse. Right .......
147: RE: K&K Line Stage - Mini Review (1.78)
Posted by DejanM on 2008-05-11, 04:56:32 (62.47.128.117)
Kevin, Just a couple of questions concerning this pre-amp. In the kit that you are selling there is also an option of buying a power supply. Is this supply already included on PCB of the active output .......
148: Re: Kevin Given Dave's Reply Above (1.78)
Posted by KevinC on 2003-03-21, 04:52:34 (205.188.208.104)
There are a variety of (untested) possibilities to eliminate some transformers in the signal path. If you are prepared to use balanced cabling between the line amp and the power amp you could drop the .......
149: Balanced in/SE out at the input of SET amp (1.78)
Posted by eyes on 2010-01-19, 09:01:47 (132.246.91.29)
Looking to use the balanced out of a tube preamp into input of SET amp. Output impedance of preamp is ~1K, so I think the LL1690 is the right choice? Max input voltage would be ~4Vrms. Unsure how the .......
150: 5687 & 1660-10 (1.78)
Posted by BAU on 2004-07-28, 13:00:43 (208.228.97.163)
HELLO I have some 5687 & 2 off 1660-10 IT & some 2a3 I try to build a SE amp & need operating points comments Love music , try to build SE - PP to many time but I am a loser ::: TO .......
151: which amp to build (1.78)
Posted by Freddy G on 2004-09-19, 12:03:06 (206.47.151.43)
Hi, I'm looking to build a stereo (or two mono block) tube amp. I have experience building pro audio gear...LA2A, Tube mics and solid state mic pres. All with Lundahl transformers by the way. I've nev .......
152: questions on the balanced line stage pre-amp (1.77)
Posted by akltam on 2004-02-05, 05:09:52 (203.168.166.42)
Kelvin, I was studying the balance line stage pre-amp offered. Why is the gain only set to only 5db. That indicated that this line stage just have a gain of around 2. Alan .......
153: Comments on 12BH7A-IT-2A3 amp? (1.77)
Posted by KevinC on 2004-11-16, 05:41:52 (205.188.116.7)
Bau Van just finished building this amp and asked me to post the schematic. He has also requested comments on the operating points. Kevin Carter K&K Audio www.kandkaudio.com .......
154: RE: K&K Audio Phono Stage (1.76)
Posted by david12 on 2011-10-03, 02:33:33 (92.21.153.55)
Richard you're description matches my findings completeley and answers a question. I still can't believe there is'nt an increase in gain. I have had to turn my amp output down by nearly a quarter, t .......
155: PP 300B direct coupled input/driver as a PP amp? (1.76)
Posted by bean on 2018-01-03, 09:46:03 (23.25.42.77)
Somewhere in my internet travels over the years, I found and saved a copy of the "rev 4" PP 300B amp schematic. With the direct coupling between the 6SN7 and the driver 6BX7, is there any issue with .......
156: Euridice Pre symetric? (1.76)
Posted by Barossi on 2004-09-20, 22:42:35 (217.236.44.168)
Hi, i have build the famous Euridice Pre-Amp with the 5842/417a tube. I use the LL1660/20mA output transformer. How could modify this pre, so that i could use it for symetric connection? What should i .......
157: Re: best driver for LL1660/10 in SE amp (1.76)
Posted by KevinC on 2003-01-23, 19:09:38 (64.12.96.10)
Well, I don't pretend to know the best choice for this amp, but I have one suggestion. To keep it simple and still get some gain, why not try a 6N1P run with about 160v on the plate and a cathode resi .......
158: RE: Line Input Transformers (1.75)
Posted by Ardee on 2008-09-18, 14:28:04 (86.135.103.17)
I would use one on an SE amp to eliminate hum loops. For P-P, they act as an excellent phase splitter as well. The only problem is that correctly loaded input transformers have a much lower input impe .......
159: Hi Y'All! (1.75)
Posted by Lynn Olson on 2002-11-06, 19:53:08 (165.121.42.160)
Really glad to see a Lundahl forum at last. Since I may have been the first in the USA to build an all-trans-coupled amp with Lundahl iron (the original Amity in 1995), it's nice to see a cool guy lik .......
160: RE: Music Reference RM-9 (1.75)
Posted by DAK on 2014-03-20, 10:40:13 (72.235.7.37)
Thank you for the tips. I will go in there and take a better look at things. I know the bias circuit was problematic when I bought the amp maybe 10 years ago. Since the previous owner gave me the repl .......
161: Tweeter Amp (1.75)
Posted by jamesB on 2006-04-24, 07:07:27 (83.216.157.229)
Dear Kevin, I'm thinking of building a tweeter amp with a 5842 driving a 71a. This will be driving my JBL2426 16ohm horns. So, i'd like to use the best xformers possible. I'm thinking of a IT coupled .......
162: Re: Transformer Recommendations/Comments (1.75)
Posted by KevinC on 2003-12-13, 11:29:41 (205.188.208.9)
- Input phase splitting - must be very well shielded LL1676 - Line stage output transformer Why not direct couple here? - Interstage transformer LL1660S/PP My signal chain would be: Inpu .......
163: All Globe Differential Headphone Amp? (1.75)
Posted by Jose R on 2006-03-28, 09:59:08 (208.201.160.3)
Its been several years since I built my first and last tube amp. I've got the itch to build another. This time, I would like to try a differential PP amp to take advantage of my balanced transport/DAC .......
164: K&K pentode amp design questions (1.75)
Posted by Francois G on 2004-12-08, 15:37:24 (129.229.32.101)
I have collected most of the Lundahl transformers and parts I need to build this amp. Has anyone else built it yet? Any comments on its performance or recommendations? At closer inspection I have a fe .......
165: RE: Ciuffoli SESS 5842 Headphone (1.75)
Posted by drsx on 2007-10-23, 10:44:00 (24.13.15.204)
So if the tube Rp were really 3K Rp of the 5842 is about half that (~1.6K). 5842 has become quite popular, and this is reflected in prices. There are other options you might look into that perform a .......
166: OUTPUT TRANSFORMERS (1.74)
Posted by merlin2049er on 2003-08-17, 09:43:42 (64.231.71.173)
Hi, I'm building a tube amp (a zen triode stereo Amp) Model SE84c (www.decware.com). I was wondering which Lundahl Output Transformers I could use for this design? And possibly where I can purchase th .......
167: Balanced Differential to SE (1.74)
Posted by Prospect on 2016-04-15, 19:02:46 (184.23.134.23)
I'm designing a power amp and need some advice. The signal coming from the pre-amp is balanced, and I would like to use a differential stage at the input to the amp to diminish any common mode signal .......
168: RE: K&K Phono Bias Adjustment Procedure? (1.74)
Posted by KevinC on 2018-02-03, 16:00:48 (99.178.170.55)
You are measuring across the wrong resistor. The correct resistors for measuring output stage bias current are R116 and R216. RThe nominal voltage should be about 1.76VDC across these resistors. You .......
169: Re: Is the highest inductance the best choice ? (1.74)
Posted by KevinC on 2003-12-15, 06:28:11 (152.163.252.5)
In this case, the additional primary inductance does not come with increased capacitance, because the coils have not changed. Capacitance comes from the coil winding geometry. I haven't done a proper .......
170: Re: buzz in Amp (1.74)
Posted by Stuben on 2006-04-03, 17:28:28 (68.170.122.143)
Guys, The chassis ground had opened. I used crimp connections on my power terminals....In my experience, this is no no... Over the past two days, I replaced all of the input conductors with shielded c .......
171: Lundahl IT's for 2 stage SE amp. (1.74)
Posted by macm75 on 2003-03-18, 05:34:28 (148.177.1.213)
Iām thinking of building an IT coupled 2 stage SE amp using the 6C45Pi and 2A3 tubes. I would like to run the 6C45Pi at 30mA. My question is will the Lundahl LL1635, rated at 20mA, be able to handle t .......
172: Re: Nice work Lynn et al... (1.74)
Posted by Jose R on 2004-09-11, 13:16:30 (24.215.241.232)
the key is good sources -> Dave Slagle Autoformer -> 3 stage amp. No two stage amp with active preamp comes close...IMHO. Hey listen, who did your power transformer? It seems to have dual CT secondari .......
173: Re: phono opt transfrmr questions (1.74)
Posted by crobin_4@hotmail.com on 2005-12-20, 07:15:12 (24.179.86.4)
Thanks for clearing that up. It sounds like exactly what I need. So at the output of the last gain stage of two (second half of the 6922) I have 200mV from a 4mV cartridge to input into the tranformer .......
174: RE: Output transformers for Audio Note M2 (1.73)
Posted by Mihaylov on 2012-09-25, 17:20:48 (178.219.32.94)
Hi Kevin! I want to add output transformers for galvanic isolation between preamp and power amp so to exclude the capacitors from signal circuit and also to decrease output impedance of preamp for bet .......
175: Help a newbie: Selecting/Using Xformer for low input impedance amp (1.72)
Posted by krikor on 2007-12-11, 09:55:44 (32.139.41.10)
I have a low input impedance power amp module (8k ohm) and would like to use a transformer on its input to present a better load for my source/preamp. Where can I go for basics about selecting and hoo .......
176: Re: PP 300B all DHT amp project [pic] (1.72)
Posted by Jeff Goldsmith on 2005-06-15, 00:32:11 (216.152.34.31)
Rafal, the filament biased amplifier stages is quite a nice little amp on it's own, but really shines as a PP stage driver. The plate current of the 71A adds to the filament string current at the 11 .......
177: Re: Output transformers for Se 45 amp (1.72)
Posted by kmtang@shaw.ca on 2008-01-21, 16:26:31 (64.59.144.21)
I brought my friend's 45 amp back home which is with LL1620AM OPT. It sounds much more natural in comparison with the one I have with LL1620 OPT. The sound stage is much wider and with more details. I .......
178: Re: Power amp for ST 70 clone (1.72)
Posted by KevinC on 2004-03-04, 04:24:10 (152.163.252.5)
When you wrote "power amp", I presume that you meant "power transformer"? For an ST-70 type amp I would recommend the LL1650. With a bridge rectifier (solid state, hybrid, or all tube), you will get s .......
179: schematic (1.72)
Posted by gluca on 2008-09-03, 13:21:30 (91.80.91.203)
sorry for the bad quality of the draft. this was a low voltage version of the spud amp to drive my headphones (the input tranny was an ex-BBC by sowter later on replaced by a LL1540, a homebrew tranny .......
180: Yes, they're worth the money. (1.72)
Posted by eyes on 2005-01-19, 17:13:29 (206.191.0.138)
Last summer I was fortunate enough to have some spare cash to throw at my DIY audio habit and purchased two pairs of the amorphous core OPTs from Kevin, one PP and one SE. The PPs were for a 2A3 PP pr .......
181: RE: PP 300B direct coupled input/driver as a PP amp? (1.72)
Posted by Tubelcain on 2018-01-12, 13:04:50 (78.111.196.165)
Hi Nerdorama. Those Russian GU-50 are still out there for nothing and come with a excellent reputation for sound quality for a IDH Valve/Tube in Triode of course I just had to do something with a pair .......
182: RE: 2 x LL1623AM/70mA sold (1.72)
Posted by kmtang on 2011-08-05, 05:01:52 (142.179.120.76)
I just upgraded my 2A3 single-ended tube amp from nickle steel Lundahl C-core LL1627 to LL1627AM amorphous C-core output transformer. The new OPTX provides much smoother, warmer and dynamic sounds. M .......
183: RE: K&K CCS Mu output - Sonic Tradeoffs? (1.71)
Posted by Maxamillion on 2012-07-08, 16:09:47 (206.228.222.37)
I've read that but I don't see how it's true, as there are still 2 mosfets between the mu output and the PSU. In any case, I'm also using a CCS-fed VR tube regulator (stacked VR150 + VR75 = 225V) so t .......
184: Claus Byrith's 30w PP (1.71)
Posted by beaufortralph on 2004-08-22, 14:04:49 (68.189.152.156)
Hi all, I am starting my second amp project - building the 30 watt PP by Claus Byrith. Any suggestions will be greatly appriciated. my thoughts are to build the PS as a seperate unit with a connectin .......
185: RE: Thanks. (1.71)
Posted by rwalton on 2009-11-18, 09:38:44 (74.109.6.57)
The amp can be biased for EL-34, KT-88 or 6550 (not sure about others). The EL-34 output tubes in the pictures were my sacrificial "startup" tubes, although there were no startup issues (of the damagi .......
186: Re: which amp to build? (1.71)
Posted by KevinC on 2004-09-21, 19:34:37 (152.163.100.6)
Hey Freddy! If you can build an LA-2A clone or a tube mic, you can build a power amp. There's a wide range of degrees of difficulty and expense available, so it might help to narrow down the starting .......
187: RE: CCS "workaround... Is it cheating...being lazy....or "thinking outside the box"? (1.71)
Posted by Tre' on 2012-07-25, 17:39:29 (75.82.52.72)
The amount of B+ doesn't change the Rset resistor value. As long as there is a voltage difference from the input to the output of about 20 volts or so* the CCS will function properly and the needed va .......
188: RE: Single stage DHT headphone amp (1.71)
Posted by hvbias on 2014-08-25, 12:24:50 (66.30.103.154)
Sorry if I misconstrued your words or misunderstood Doug. It has been a long time since I last messaged you and I might have mentioned using a phono stage that only output ~1v with my cartridge. But I .......
189: K&K SE phono question (1.70)
Posted by Ole on 2005-01-18, 05:54:34 (80.203.121.34)
Is the upgrade kit on the K&K web for older version of the SE phono or do I have to order the upgrade as well as the phono kit to get an up-to-date K&K SE phono amp? Thanks, Ole .......
190: Re: 45 driver for 300b (1.70)
Posted by KevinC on 2006-10-17, 08:55:14 (72.150.154.52)
You could build a 6SN7GT -> 45-> 300B SE amp. If you access some of my PP amp schematics, you can see how this could be done. I normally favor choke loading the first stage and direct coupling it to t .......
191: Re: Line stage/Headphone amp (1.70)
Posted by KevinC on 2004-01-21, 04:32:07 (152.163.252.5)
Brian, You could use the LL1630/PP as a parafeed output transformer connected 7.2:1. Paralleling the secondaries to get 14.4:1 will result in some high frequency roll-off, though. I don't think that i .......
192: about 6c45 (1.70)
Posted by akltam on 2004-12-13, 17:36:45 (63.137.52.3)
Kelvin, I am driving my 6C45 into the 30mA plus region. When I drive the 6C45 increased from around 25 to 30mA, I notice that the music is much more preferred and much warmer. Right now, I am driving .......
193: Music Reference RM-9 (1.70)
Posted by TMASLAR on 2014-03-01, 11:28:07 (24.229.102.39)
Hi Kevin, I am in the process of bringing a Music Reference RM-9 back to life. I have heard that you had done some modifications to these amps. Are there any areas that you feel offer worthwhile impro .......
194: PPP 6550 Amp Enquiry (1.70)
Posted by Tubelcain on 2010-04-25, 14:11:27 (88.81.133.17)
Dear Kevin, With the 300B push pull amp based on your designs still sounding absolutely wonderful and my solder fume adiction bitting hard. I am planning to go active and build my self one of your Lun .......
195: Output transformers for Se 45 amp (1.70)
Posted by tnc on 2007-01-27, 09:41:01 (66.142.142.157)
Can someone please suggest a nice set of output transformers for a Single Ended 45 tube amp. I've heard many nice things about Tango, Tamura, Electraprint, Magnaquest but never Lundahl. Would Lundahl .......
196: Hey Kevin....... (1.70)
Posted by thermionic addictions on 2006-10-19, 13:14:08 (71.210.59.101)
Regarding the amp circuit you described in a post below (6J5 direct coupled to 45) is it necessary to bypass the cathode resistor of the output tubes with a cap? I have played around with direct coupl .......
197: 6h30 LL1660 Line amp (1.69)
Posted by haukito on 2007-05-13, 00:29:40 (90.186.96.19)
Hi, i would like to change the tubes from 5842 (single triode) to 6h30 (double triode) in my line amp.I am using the LL1660 which should work with both tubes! No my question: I have 2 noval sockets an .......
198: Re: Your platechoke loaded KT88 amp (1.69)
Posted by KevinC on 2003-09-19, 06:37:50 (205.188.208.9)
Alan, I am afraid I haven't compared them directly in a controlled way that would yield reliable impressions. However, in theory the PP plate choke does the very valuable service of helping to ensure .......
199: RE: Upgrade for Cayin A88T integrated amp (1.68)
Posted by KevinC on 2010-01-28, 14:16:10 (72.150.136.213)
The 240v running with a 220v nominal transformer just means that all of your voltages are about 10% high, assuming they were nominal in the first place. That might reduce tube life, but I would be inc .......
200: RE: Line Input Transformers (1.68)
Posted by Walstein on 2008-09-18, 13:37:04 (209.121.88.140)
What is the advantage of using such a Line Input Transformer? Can they be added to any SE tube amp? I am thinking of building an amp that calls for a Line Input Trafo. If I don't like the result, I'll .......
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