Problem is solved!!!
Dear friends (may I ?),
Trusting your remarks, I have just experiment in completely different direction & locations in my all HiFi chain.
Indeed, once the OpAmps have been mounted directly on the PCB, the all sound became very strong: It was not anymore possible to handle it just “as it is”: There has been much too much midrange, no transparency, not enough highs, all that what I described before…
The mistake had to be found indeed somewhere else: First of all, I simply changed now the polarity of ALL 3 palatine-rhodium power cables: On the Active Subwoofer, on the Power-Amp and on the Pre/DAC. Already with this, almost everything came to its place "at once".
Not yet being done, I noticed that I have a new matched-pair of the Bursons Discrete OpAmps which I was about to replace sometime (I am normally using s pairs of them in the I/V - behind the DAC). One of the old was indeed damaged before!! Now there is a new pair inside...
Wow! What shell I say? I listen to your advices and decided NOT to go backwards to the sockets. So what I did find is that it has been this combination of 1x damaged OpAmp and total wrong compensation through the rhodium cables.
Removing the sockets indeed yielded in small improvements. Smal improvements? I am not sure if it is so small... Well, putting the OpAmps directly on the board caused a tremendous impact on the all system. Not a bad conclusion after all!
Special thanks to all of you!
IY.
Dear friends (may I ?),
Trusting your remarks, I have just experiment in completely different direction & locations in my all HiFi chain.
Indeed, once the OpAmps have been mounted directly on the PCB, the all sound became very strong: It was not anymore possible to handle it just “as it is”: There has been much too much midrange, no transparency, not enough highs, all that what I described before…
The mistake had to be found indeed somewhere else: First of all, I simply changed now the polarity of ALL 3 palatine-rhodium power cables: On the Active Subwoofer, on the Power-Amp and on the Pre/DAC. Already with this, almost everything came to its place "at once".
Not yet being done, I noticed that I have a new matched-pair of the Bursons Discrete OpAmps which I was about to replace sometime (I am normally using s pairs of them in the I/V - behind the DAC). One of the old was indeed damaged before!! Now there is a new pair inside...
Wow! What shell I say? I listen to your advices and decided NOT to go backwards to the sockets. So what I did find is that it has been this combination of 1x damaged OpAmp and total wrong compensation through the rhodium cables.
Removing the sockets indeed yielded in small improvements. Smal improvements? I am not sure if it is so small... Well, putting the OpAmps directly on the board caused a tremendous impact on the all system. Not a bad conclusion after all!
Special thanks to all of you!
IY.
burr brown data sheet. here's the small signal gain charts. notice the peaking around 150 and 200 Mhz. that's instability.
did a search on www.datasheetarchive.com
the first gain curve on page 1 LOOKS like unity gain stable, but look at the bottom of the Y axis. it begins at +66db
did a search on www.datasheetarchive.com
the first gain curve on page 1 LOOKS like unity gain stable, but look at the bottom of the Y axis. it begins at +66db
Attachments
The Burr-Brown datasheet I got, shows circuits on several pages that the OPA627 is Unity-Gain (can't post it here as it's 258kb but you can get it from www.alldatasheet.com)...
Furthermore I have many times used the OPA627 with a gain of 1 and never experienced any problems what so ever......
Furthermore I have many times used the OPA627 with a gain of 1 and never experienced any problems what so ever......
Re: Problem is solved!!!
There are many, many very excellent amnps out there without sockets (sockets are for the diy-ers and amateurs; they add unneccesary costs to a product).
Furthermore, almost everyone recommends leaving out sockets to AVOID the extra interpin cap that can cause oscillations.
This is typically a case of thinking that if something is possible it must be true. Sure, sockets or not change mech vibration characteristics of a board-with-opamp. Therefore it MUST be audible? No way Jose!
Bottom line: everybody says no sockest is best. You say: I removed sockets and now it sounds bad. I say: there's something else going on.
Jan Didden
irgendjemand said:
There are many, many very excellent amnps out there without sockets (sockets are for the diy-ers and amateurs; they add unneccesary costs to a product).
Furthermore, almost everyone recommends leaving out sockets to AVOID the extra interpin cap that can cause oscillations.
This is typically a case of thinking that if something is possible it must be true. Sure, sockets or not change mech vibration characteristics of a board-with-opamp. Therefore it MUST be audible? No way Jose!
Bottom line: everybody says no sockest is best. You say: I removed sockets and now it sounds bad. I say: there's something else going on.
Jan Didden
Re: Re: Problem is solved!!!
jenneman,
this is pure misunderstanding!!
I wrote on my very last post (which you are quoting here) that "I listen to your advices and decided NOT to go backwards to the sockets". Instead, I did find that the problem was somewhere else: I came to a conclusion that you have been right!
What I was saying in addition is that I didn't expect such huge different in the all sound characters after removing the sockets. Sound became bad, but obviously NOT because of removing the sockets themselves!!
I see it as a matter of balancing the system: While the sockets have been in (only for trying different OpAmps !!) the sound was not so strong as without them now. I compensate for it at the time with cables, etc.
Once the sockets are out – AND THEY SHOULD BE OUT! – I got a “wrong” sound at first. But, once again, this was indeed for different reasons. Just as you said, there was something else going on. Thanks again.
jenneman,
this is pure misunderstanding!!
janneman said:
I wrote on my very last post (which you are quoting here) that "I listen to your advices and decided NOT to go backwards to the sockets". Instead, I did find that the problem was somewhere else: I came to a conclusion that you have been right!
What I was saying in addition is that I didn't expect such huge different in the all sound characters after removing the sockets. Sound became bad, but obviously NOT because of removing the sockets themselves!!
I see it as a matter of balancing the system: While the sockets have been in (only for trying different OpAmps !!) the sound was not so strong as without them now. I compensate for it at the time with cables, etc.
Once the sockets are out – AND THEY SHOULD BE OUT! – I got a “wrong” sound at first. But, once again, this was indeed for different reasons. Just as you said, there was something else going on. Thanks again.
. Sorry.
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