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I just upgraded the opamps on a Rotel 965BX to BB 627's. It was my first time doing this type of mod and all I can say is WOW!!
The player has become a little harsh though, which does not completely surprise me. My question is how long does it take for the opamps to smooth out (assuming they will).
Follow Ups:
No problem removing the output coupling caps, but how can I identify them for sure? I havent opened the Rotel back up yet (awaiting the clock from Net Audio) but are they the caps close to the opamps?
Also, does anyone know how to identify the muting transistors? I would like to bypass them but have no idea which ones they are.
if polar caps are used which means a big yes for Rotel, the negative stripe points toward the rca jacks at the back as signal flows from positive to negative..if you removed these before you bridge with a wire, plug your cd player in and listen, if you hear nothing, you pulled the right caps.. anything near the op amp(within 1 cm or 2 probably are power supply bypass caps, bridging these with a straight wire will be bad news and provide you with a nice low impedence current path to ground and possibly would fry your regulators quite quickly in the process..
Colin
Harsh?, dd that you find that with the 627's, if anything they should sound closer to warmer than harsh..Im not familiar with the 965 but i use them in my rcd-02 and find them anything but harsh...If your cd player is similar it uses a toal of 4 opa 627;s to make two dual modules?..both these ops are bypassed from =/- to ground with 100uf black gates??..try bypasssing each of these with a .01uf polypropylene cap of your choice, for myself i used wimamkp 10's to much benefit...what was in the player before(op amp wise) before you changed them??
I do not know what Rotel used in the 965BX for opamps. I did not recognize the brand and I couldnt find any info re: the opamps when I searched previously. It used one opamp per channel.
Dont get me wrong, the 627's are phenominal. The Rotel sounds MUCH more musical. It was just initially, certain highs were a tad bright. But, that is already resolving. Actually, the amps seem to be losing a little resolution now. I dont know if this is related to the break-in process as the amps smooth out. But I am overall very pleased with the results. I am now waiting for the clock I ordered so I can get it installed. I only hope I get half the results that I did with the opamps!!
I will try your recomendation with swapping the caps. I dont know the values off-hand, but I will check them. Where would be a good place to purchase the caps you mentioned??
Thx for the help!!
The 965bx used ne5534 Signetics 'S'logo, now made by Philips.
Adding a clock to this player gives tremendous resolution but may sahve off some musicality IME.
Ah!!! That would explain the "S" I saw on the opamps, thanx!!!
There was a third chip more towards the center of the board that also looked the same as the opamps but had diffrent numbers on it. Any idea what is is?
Sorry, It's been a while and I forgot most of the layout, it's probably some I/V conversion or something to do with the transport.
FWIW, leave the BG's (6) near op-amps where they are along with those surrounding the DAC, do not bypass them as they would change their unique character, Try to eliminate the small RCA pcb, and solder better sockets directly to the main board using the original wires !!!, use only audio dedicated solder for all applications. That's about all I can contribute at the moment, changing to many components might alter this player's unique, if imperfect, character.
Thanx for the advice!!! Actually, years ago I completely bypassed those small 4 pin connectors (white, like on a sound card) and the connecting wire, and soldered silver IC wire straight from the board to the RCA jacks. I also replaced the power cable and bypassed the fuse and power button.
Swapping those opamps though, that was incredible. I agree with you, the Rotel has a unique and pleasing character, unfortunately its kept its character in a box at the bottem of my closet for years now because it just couldnt compete with newer, much cheaper stuff. Now its been resurrected as it were, and I couldnt be happier. Wish I hadnt blew the front display and control buttons during the mod :..(
Do you have any opinion about bypassing the muting transistors? I dont know where they are though.
Muting Transistors look like three legged half barrels and are frequently located right next to the o/p caps or resistors, they shunt commands switching noise etc. Bypassing them is like losing any other noise adding component when removed, but they keep from damaging the device and speakers in high volume. I can't tell you which pins to bypass specifically in this player.
I wish you kept the original RCA wires, as I recall they were the most transparent ones I've tried.
Check the wires from the transformer to the pcb and display braids at the soldering points, they tend to tare after some fiddling around, and sometimes this tare is not visible, this might bring the display back to life. I recall it happened to me with this player, I lost the display but In my case I could still use the controls.
I cut 10mm of each wire's tip coming from the transformer to the pcb, at the pcb's end, re-soldered them and everything was fine, do that with the display braids as well and don't forget to mark each wire !As I mentioned before, a clock might give a much higher degree of resolution, something you find in recent cheap players, but can diminish some musicality.
Actually, I think I still have the wire. However, the wire I used to swap it was the same as my IC's (Audioquest lapis silver), so I doubt it could have been a better match. I would have left the wire in place had I known it was that good though. It did look a little unusual.
I appreciate the suggestion, but me thinks the front panel is blown. I plugged the ribbon cable in wrong. If you recall, the male connector on the board was four pins longer then the female connector that plugged into it. I didnt pay attention whem I removed it (the extra length was obscured by the cable and transport). When I went to plugit back in I knew I had a problem, and I guess I zigged when I should have zagged!! What sucked was I looked everywhere on the net for some kind of reference before hand but could not find one. Of course, the next day I accidently ran across exactly that which I was looking for. Oh well, atleast the remote works!! And I dont have the annoyance of the display light anymore!! :-)
I hear what your saying, dont change too much. Ok, I will change the clock, and the new capacitors supplied by Net Audio, which were changed in the LE version and I will leave it alone!!
This will probably be my main player for now, being as it sounds pretty darned good, and then when I get the wifes blessing (permission), I will start looking for a Rega Apollo. Unless that clock really does some magic!!!!!!!! (and if I dont blow something else up again!!).
I wish I could let you off that easilly...I Just could'nt ignore that remark about the LE vr. caps. Just that you know, the LE version sounded inferior to the BX, not just me saying so, and the main difference between the versions was the caps, but hey, putting back the original caps is no biggie especially if you have a good de-soldering device.
Yes, soldering the original caps back in would be no big deal, getting at them is a whole other story! Could you please follow this link and tell me what you think about this upgrade. I have read reviews on the net-audio clocks and they were positive. I ordered the micro-clock kit.
http://www.net-audio.co.uk/965discrete.html
I did the opamps myself, opting for the 627's. So all I would have left would be the clock and those two capacitors. I did ask David at Net-Audio why replace the caps because the originals looked like good quality, and he simply said the replacements were superior.
I tried the 'SuperClock III' by Trichord and as I mentioned, I got awesome resolution but lost some 'liquidity' and the 965bx's trade mark musicality as a trade-off. Maybe your clock choice would prove better.
And what would you expect from the caps dealer to say?...
I'm stayin tuned!
Ok, thanx for all your help!! Ill let you know when it arrives and I got it installed!!!!
just use the small value polypropylene(metallised) soldered in paralell with each electrolytic that bypasses the power supply rails..Another thought that just came to me that i forgot to mention, since the opa627 has an insanely low dc offset you can laso safely remove the cheap electrolytic output coupling caps(these can be found near the output rca jacks, negative stripe will point towards these.. Use a wire jumper to rebridge this path sans cap, if you have a voltmeter handy measure the dc on each output, it should be under 1mv after this mod...I found this tweak to give more extended highs and a little more body overall...
Colin, I have some specific questions about your suggestions that I would like to implement. If you have the time, could you email me so I could discuss them with you?
According to the reference I have, the ROTEL RCD-965BX used a SAA7323GP DAC.
In your reference, does it indicate where the muting transistors are? I read that it helps to bypass them? But, being as I am new to this level of mod, I have no idea where they might be. If you know where, please be as descriptive as possible. I want to bypass the mute feature, not permanetly enable it!!:-P
My reference only lists the DACs used in various CD players.
nt
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