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HAS ANYONE BUILT OR HEARD THE ALLEN WRIGHT DESIGNED RTP PRE-AMP?I AM USING THE ATMA-SPHERE M-60 MONO BLOCKS THAT I BUILT FROM THE KIT SOME TIME AGO.I AM LOOKING FOR A BALANCED PRE-AMP DESIGN TO BUILD.TO MY KNOWLEDGE THE VACUUM STATE IS THE ONLY ONE AVAILABLE IN KIT FORM.DOES ANYONE HAVE BALANCED PRE-AMP DESIGNS THAT COULD BE BUILT UP FROM SCRATCH AS AN ALTERNATIVE.THE VACUUM STATE KITS ARE REALLY PRICY.I DO NOT KNOW HOW TO ESTABLISH IF THEY ARE WORTH THE ASKING PRICE.ANY FEEDBACK WOULD BE GREATLY APPRECIATED.
Follow Ups:
Hello,you may have a look at the homepage of borbely audio: www.borbelyaudio.com
There you can find an article describing a 'Balanced Line Amp with Tubes'. Mr. Borbely sells kits, mainly Mosfet/Fet. I didn't hear or build this kit and thus can't say anything on sound or quality.Chris
I echo Mikey's suggestion. However, if you want to build Allen's kits (which are excellent designs BTW, and are state of the art if built to spec), why don't you just build it by the schematic? You don't have to buy the kit because he freely releases the schematic on his website.If you are uncomfortable with this, you can just buy his boards with parts and not buy the chassis and build a chassis of your own or have somebody like Spire Audio or IAG (International Audio Group) to build a chassis for you. IAG is run by Horace Atkinson (he's also the U.S. distributor to Sowter transformers) his e-mail is: hatkinson@hot.rr.com
This will take some planning on your part and time of course. But if you built the M-60's (I don't know if you did, I'm just assuming) you will understand the extra work required in balanced circuitry.
I for one think that Allen Wright's chassis' are stunning (far more stunning than similar commercial offerings including Atmasphere) but expensive as well. You might just be able to build his boards, wip up a power supply (either his or your own) and stick it in a good $150 chassis as opposed to a $500+ chassis.
But if you do build Allen's fully balanced preamp kit I don't think you'll worry about anything else out there. It's that good of a pre.
AnandR.
Guys,
What can I say? One thing is that I have always found a differential circuit to sound comfortably better than a near identical single ended one - so I have to say to Mikey that just adding (even a MQ) transformer will not do the same thing sonically.And that was even with the first differential pre's back in the 80's that were unbal in & out but diff internally, they were still well ahead of anything unbalanced.
Pricing - yes they are expensive, but If you've checked the website you will see that all the modules are available seperately, or as others have suggested, you can build it up yourself from the schematics on the site.
But I realise that this is a pretty steep gradient as they do not give any of the fine details you would need to do the job exactly as a full VSE design - so If you are REALLY keen - I would be prepared to sell you the actual assembly manuals for each module. These give the full schematic including heater supplies, bias supplies and step by step instructions with lots of clear & large drawings showing all the wiring, parts placement etc etc.
Email me directly if this is of interest.
Finally, we intend releasing a much lower cost kit of the FVP5A this autumn - it will not use the massive chassis of the expensive kits, and will have everything on one big PCB - but should sound pretty dang good. There is a review of this design (a single ended pre - pretty much half a RTP3C) at
< http://www.tnt-audio.com/ampli/vse_fvp5a_e.html>
Allen
PS Mikey - did you get that 230VAC SACD player yet? I haven't heard anything back since I shipped them... We are about to be able to ship the update kits if you are interested.
For what it's worth I wholeheartedly agree with Allen's sentiments here.Differential every time - and balanced - and cathode follwoers with active loads - it really works!
How's motoring in Germany these days Allen? (Speed camera crap in police-state England I'm afraid!)
7N7
7N7(perhaps a little envious) asks:> How's motoring in Germany these days Allen? <
Minimal speed cameras - depends on which state it is. Never seem to be just for $$ collection. Never seen one in Bavaria on the autobahn - but my girlfriend got busted last year doing 120 in a 60 klick autobahn roadworks area - but at 2AM in good weather...
Main problem is the traffic density, not much fun having a quick car and having to sit behind streams of ^%$#@! Dutch caravans passing trucks. But pick the right time of day and the right day and it can be a blast!
Allen
I hear ya, be glad you aren't living in the states. Don't think people here know what they're missing. Wish I could take my car back to SA for a week or two :)Peter
Hello Allen:> > What can I say? One thing is that I have always found a differential circuit to sound comfortably better than a near identical single ended one - so I have to say to Mikey that just adding (even a MQ) transformer will not do the same thing sonically. < <
I suspect you may well be right on this. I suggested this approach as not "ideal" but just a practical option amongst many other options. Didn't mean to imply that it was the favored or best sounding.
Some of the application areas that you have focused on just hasn't been explored as much in contemporary times at least not so much here in the states.
I've done some (for my own edification) black box diagrams and conceptual studies of differing circuits... going from fully differential to single ended-- phase splitter--- output. And especially at the small signal level (preamp level) just haven't done anywhere enough studies (or lstening)to have formed a founded (i.e., well grounded) opinion.
I would quickly defer to folks like yourself.
> > Pricing - yes they are expensive, but If you've checked the website you will see that all the modules are available seperately, or as others have suggested, you can build it up yourself from the schematics on the site. < <
great flexibility there folks. And I will say that all the feedback I have ever gotten on Allen's products have been positive. And he's supposed to be a brainy dude as well!!!!
> > PS Mikey - did you get that 230VAC SACD player yet? I haven't heard anything back since I shipped them... We are about to be able to ship the update kits if you are interested. < <
Steve Dear has them out in Hershey and on his next trip into the city of brotherly love is going to deliver mine. In the meantime I need to wire up and house the autoformer power trans to get from 120 volts to 220/240 volts. Do you remember which voltage the unit wants to see (220 or 240)... I also suppose that it has a regulated power supply and probably works within that range but my trans has available taps at 200, 220 and 240. Suggestions?
thanks Allen,Mike
Wow!! the asylums just keep getting better. NExt we'll be talking about beer and BBQ, and after that gumbo.Differential circuits have been, somewhat dissed around here. I think the problem has been that most implimentations drive them with a unballanced circuit and ground one grid needing local and global feedback to work well, if at all. The wacko circuit I've been using as a driver is a pair 0r 6S(C)45s, single chip CCSs and a battery bias driven with the 8920. The 6S45s aren't the best for matching, and maybe the worst tube to use but I like the sound. I keep thinking about using ECC99s but just haven't tried them yet.
Hey, could someone be so kind as to connect me to Steve? Beer + BBQ +SACD+differential sounds like a good afternoon, hope he likes Little Feat. 120 to 230 aint no problem.
Mike,
> Do you remember which voltage the unit wants to see (220 or 240)... I also suppose that it has a regulated power supply and probably works within that range but my trans has available taps at 200, 220 and 240. Suggestions? <The sticker on the back sez 230VAC. Nothing seems to run too warm inside so I'd suggest setting for 240 and have a few extra volts of headroom.
Allen
PS Can you contact me directly via email - I have a transformer question/quote needed
Fine looking gear. Don't care much for the JFET input, though. And what's this about differential circuits sounding better than single-ended ones? Are you saying that phase splitters in general sound better than SE triode stages? Or is it that they sound better than SE triodes followed by a transformer?RD
RD asks:
> Fine looking gear. Don't care much for the JFET input, though <I suggest you only criticise if you've tried it in this topology and found it wanting - OK? But the latest MC phono uses the MAT02...
> And what's this about differential circuits sounding better than single-ended ones? Are you saying that phase splitters in general sound better than SE triode stages? <
I'm saying that REAL differential circuits (and that discounds 99% of all phase splitters) sound better than similar topology single ended circuits! I'm not saying that all differential circuits sound better than all SE circuits - just in my experience my diff circuits are certainly better sounding than my near identical SE - all the way!. And in a REAL differential system, there is no need for phase splitters anyway.
But as there are almost no real differential circuits out there, not too many people have had the chance to compare. The Atmasphere gear is only quasi-differential.
> Or is it that they sound better than SE triodes followed by a transformer? <
I am not a fan of using one more transformer than must be used so would never have a transformer at the output of a preamp for example. The only transformer in my system is the output between the power tubes and the speaker. And so far - no SE poweramp (300B/845/311) has, to my ears, has bettered my differential (not plain push-pull) poweramp using basic EL34s. Going differential provides the same microdynamics of the best SE amp with the vastly superior bass tonality and control of a very good P-P amp. The fact that the powersupply is largly taken out of the sonic equation certainly helps this.
Allen
> I suggest you only criticise if you've tried it in this topology and found it wanting - OK?But I HAVE tried that topology. Just like you, I passed a signal through a JFET. I don't like the results.
> The fact that the powersupply is largly taken out of the sonic equation certainly helps this.
I didn't know that was possible. Maybe you could elaborate?
RD
RD:
> But I HAVE tried that topology. Just like you, I passed a signal through a JFET. I don't like the results. <I don't mean passing a signal through a fet - I mean using the exact jfet/tube cascode used in my designs. Exactly what topology did you try that you didn't like? As in *exactly*...
> The fact that the powersupply is largly taken out of the sonic equation certainly helps this.
I didn't know that was possible. Maybe you could elaborate? <A perfectly current sourced diff amp outputs between it's two outputs ONLY the difference between it's two inputs. So if there are any unwanted stuff on the powersupply then it's exactly equal on both outputs and doesn't affect the difference signal.
A unbalanced amp has it's powersupply as part of the main signal loop - so it contributes HUGELY to the sonic flavour. In a 'perfect' diff amp this powersupply colouration can be reduced 60 -80dB or even more - without any negative feedback to make other problems!Allen
"But as there are almost no real differential circuits out there, not too many people have had the chance to compare. The Atmasphere gear is only quasi-differential."If you don't mind going into more detail on this point, I'd be curious to hear why you call the Atma-sphere amps quasi-differential. My understanding was that they were fully differential.
Thanks,
Doug
Doug asked:
> If you don't mind going into more detail on this point, I'd be curious to hear why you call the Atma-sphere amps quasi-differential. My understanding was that they were fully differential <I'll prefix by backing down a little in my previous statement, because I've yet to measure them.
They certainly are intended to be differential - but my complaint with them is that their current sources are less tight than they could be, which would lead to a less than optimum CMRR (common mode rejection ratio) which in turn would make them operate less than purely differential. A 'soft' current source also makes the power supply's influence much greater - and he's not using shunt regulators - which I consider vital for optimum sonics in any equipment. And the circlotron type outputs in both pre & poweramps have many positives, but are certainly not differential.
My experience - YMMV...Allen
You busticatin' my eyeballs. Nobody likes being shouted at.
Hello. For balanced preamp out (in kit form)... doesn't AtmaSphere offer a balanced pre? I thought they did in kit form as well... but I could be wrong.Other option... is to build (though I don't know of any "kits") say a tube preamp and use an output with a CT secondary to get your balanced signal on the output.
MSL
Mikey, you need a marketing guy. Transformer output is inherently balanced. If he needs a zero-volt reference, give him a center tap.Sorry, I didn't mean it. You're not a doof. You're a genius winder, but you're not a genius salesman.
Poinz
And that's why I love Doc!!!! He is.smiles Poinz and Doc.
Mikey
Cobalt B7 now available.
Sigh.
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