|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
172.242.215.34
From what I have heard, the factory op-amps are, or equivalent to the LT 1056 amps. I would like to replace/upgrade to better op-amps any suggestions? Thanks!
Follow Ups:
Hi,
Why don't you use discrete opamps like burson or audio-gd? To my ears they blew away standard opamps wich will never come-back in my cdp!
:)
Here's some of what have learned about op-amps. OPA-op amps are good but have very dark color, I won't use them anymore. I now like LM's very much. Put 6800uF at every power pin of the op-amps, all the op-amps. This will make your op-amps disappear, no more noise, no more distortion! Bass, as good as the circuit can deliver.
Good Luck, bobwire
Hi and i think you are very right indeed
This is a point very overlooked. The op-amps to sound clean and powerful need many and fast uF very close to them.
I have a Hegel preamp ... a P20. I see many OPA604 inside with quite big caps (i see 1000uF/63V) very close to the OPA. The sound is very clean and powerful. Not the typical hardness associated with op-amp.
For me the caps are like dampers and music like a rough path with ditches and hills.
The smaller the caps the less energy is stored and then available during music peaks.
I think that a good starting value could be 470 uF of very good quality.
But i could even use up to 2200uF ... the working voltage is usually low and so also prices for these caps.
I have here a nice heaphone amp with powerful op-amp buffers (250 mA or current available) but almost no caps close to the buffers.
I find the sound clean but hard. I am completely sure two big caps would have changed the sound for the better. I am sure of that.
A little sharpness in the details, instead, can be effectively tamed with break-in and the right cable selection (i.e. copper solid core o litz wires).
I am keeping this preamp. Even if it is op-amp based (scandal !).
I have also an old Electrocompaniet 4.5 fully discrete and more rounded and soft.
I like the transparency of the Hegel better.
Very clean line stage indeed.
So op-amps can be extremely good when rightly used.
Thanks again for confirming a sensation.
Kind regards,
bg
Edits: 05/17/15 05/17/15 05/17/15
If you really want to 'improve' the 565, you should hunt down the extensive mods performed by Gary Galo and detailed in 4 parts over four issues in AudioXpress, starting in the Nov.2003 issue.
In the Dec. 2004 issue he followed up with a final article covering options for line stage opamps.
I do have Part 1. (in issue Nov 2003) scanned on my hard drive if you would like a copy.
I concur,
The AudioXpress articles are excellent. As someone also mentioned some chip (s) are not standard op amps. The LT1010 driver is used there it's a buffer, I don't recall what they used to replace it if they did but you could use a BUF-634 or National/ TI LME49600. Some of the Natl/TI Op Amps LME49 series and others developed after the article was written can replace the other op amps. This was kind of like the Valkyrie Line Stage by Grayson in the 90's which I believe was a thesis or College project for him with some involvement by Gary Galo. If you want some more info I'll look and see if I have a pdf of article and some related info [drop me an email]. As always the road leads back to Walt Jung's Pioneering work with the composite op amp. Tons of info from him also, Google Walt Jung.
DagW00d
I owned the 565 in the 90's, it was a killer pre-amp in stock form.
Kat-
what are you attempting to accomplish by changing out parts?
If the opamps are in fact LT1056's I wouldn't bother. They are quite good.
You had also better have the service manual as not all the IC's used in that preamp are opamps.
Dan Santoni
Yes I have the service manual and understand your point, I have some OPA627BP amps as samples on hand and thought about trying those along with extra decoupling and bypassing anyone else tried that same combo? Thanks Blackdog!
Do you need additional bypassing? Is there any RF on the signal lines? You cant cure something that isn't there. The LT 1056 op-amps are fine. You wont notice any difference. They are being used far below their limits.
I don't own a scope or, know how to use one for that matter. I just figured since the unit is 25 years old and runs in pure class A that it might be a good idea to change out and upgrade if possible, while I'm at it. Thanks!
I bought some of these and have been quite successful. Lookup the substitution to make sure they are appropriate. I found that it substitutes for a LOT of op-amps, but maybe, not all.
The most important thing is to have the op-amp socketed, otherwise, how can you change it out? Removing a non-socketed op-amp ranges from requires some skill to nearly impossible and it depends a lot on how tight the hole dimensions are. I suspect that you will be OK with that, but I had a German made PCB with impossibly tight tolerances that was muy difficult.
LME49860 [x4] 44V Dual Low Noise OpAmp with Machined Pin socket LME49860NA
I just got LUCKY and changed out a shore power connector on a circuit board from a friends laptop device. At least 8 solder in connections. Crazy tough with my bad eyes. BUT, it worked and nobody was more surprised than I. I love solder wick.
As for opamps? Any fans of the OPA2134 ? I make copies of the CMOY headphone amp out of 'em and they are NICE. I've reached a happy place with gain and sensitivity.
Too much is never enough
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: