 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
Hi,I'm using a Quad 44 for some time now and I'm quite happy about its performance. However, I would like to upgrade some components in the pre-amp (just for fun) and thought it would be best to start with the op-amps.
The Quad 44 uses old TL071CP opamps on every input card (5 inputs, each input uses two TL071CP's so that makes 10 opamps). Further it uses at least four TL071CP's at the amplifier circuit board.
I did some research and narrowed my choices down to three different Burr-Brown opamps. I chose the OPA134, OPA604 or OPA627. Pen 5 and 8 from the OPA134 are twisted with pens 5 and 8 from the TL071. Pen configurations of the TL071, OPA604 and 627 are the same.
It would be possible to use the OPA134 on the input cards because pens 5 and 8 aren't connected. This is not true for the amplifier board.Well, my question is, which of the three opamps would be best? According to the specs I would choose the OPA627, but this one is much more expensive than the 134 or 604.
So maybe I should choose the 627 for the phono input card and use 604's for the other input cards and amplifier board.
Would this be the right choice and can I substitute the TL071CP with the OPA604 or 627 without changing anything else (just drop-down replacement). I ask this because I'm not an electronics engineer and don't have much knowledge about opamps.One more question about the TL071CP. There are two lines on top of this opamp. The first line says TL071CP and the bottom line is F7949B (the AUX and TAPE input cards), but the second line of the opamp at the phono card is 7941. Does anyone know what this stands for, is this just a date code?? The lettering (font) of the opamps on the phono card is also a bit different than on the tape card.
I don't want to bother you all too much but does someone also know for a better replacement of the CD4066B solid state switches?
If anyone knows more modifications for a Quad 44 or 303, please let me know. Feel free to email me.
Can anyone also provide me with a link where I could buy the above opamps online?
Thanks in advance!!
Regards,
RB
Follow Ups:
I would recommend the OPA 604, as it is a lot less likely to oscillate or drag the PS down when dropped into an existing PCB. The 627 is a superior op-amp, but the sheer bandwidth and current draw will likely pose problems.The second line is indeed a date code.
Jon Risch
During my time off this Xmas I upgraded the op-amps in both my Classe' Ten power amps. They had TLO72's and OP27's in their front ends. First however I did the two regulated supplies for these op-amp's. One pair of +/- 15 volt suppies for each channel. That open up the sound a lot!! Then I replaced the op-amps with AD712's and 711's. These are pin for pin and very low offset. For speed there about the same as the TLO72 but five times faster than the OP27. DC spec's are way better than the old op-amps too. My NEW TEN's are nothing like before. A big blanket was removed from over the sound and focus is very sharp. I have miles of depth and width. Now when I play a CD I'm moved not just into the recording studeo but right up front of the players. Even old CD from old recordings sound new and cleaner. Bad live recordings don't sound the same because hum and feedback and all that are behind my listening position. New stuff is very life like. Enya dropped the floor out from under me. My Maggies have never sounded so good. All from eight caps and eight op-amps! So, go for it, and replace those bad boy's and see what comes out of your system. Good Luck, bobwire
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]