The Opamp thread
Jul 26, 2023 at 5:09 AM Post #7,291 of 7,383
Dip8 is footprint of most trough hole opamps. Soic8 is the smd equivalent. Seeing pictures in reviews of your amp, it is dip8, and they supply 5532 opamp in dip8. If you can open it and send picture directly here, i can tell for certain.
 
Jul 26, 2023 at 3:57 PM Post #7,292 of 7,383
You can't compare cmos opa back in the day and now. Burson v6 is probably the best opamp on the market for dip8 atm, i agree. But 1656 comes damn close to it as ic opamps go. Now there are specific cases where you want specific opamps, and as i said i can't see schematic of the device in question, so i can't tailor my answer specifically, hence my recomendation to start off with something that is cheap, sounds better than most if not all ic opamps in most cases, before trying to mod the device with something as big as bursons.

Yes, v5i is really bad. Blunder on marketing (it is not a hybrid) and blunder on what was achieved. People were biasing ic opamps to class A before. Not something that stood the test of time obviously, else we'd see it quite more often. Also the biasing is done wrong (wrong per say, as it is much better, less noise and linear to bias with transistors instead of only a resistor).
Agreed, CMOS has come a long way since the old days.

OPA1656 is pretty versatile (will improve basically anywhere), so I guess is a good recommendation.

Though I will say, consider OPA828. They're pretty pricey but audjade sells them presoldered.
 
Jul 26, 2023 at 5:10 PM Post #7,293 of 7,383
Agreed, CMOS has come a long way since the old days.

OPA1656 is pretty versatile (will improve basically anywhere), so I guess is a good recommendation.

Though I will say, consider OPA828. They're pretty pricey but audjade sells them presoldered.
OPA828 is too fast for many devices. Very likely to cause oscillation unless you know what you're doing with a scope.

IMO, if someone is wanting to spend more on opamps, I'd advise just going with a reputable outfit offering discrete designs like Burson or Sparkos.
 
Jul 26, 2023 at 8:00 PM Post #7,295 of 7,383
How do you mean too fast ?
Faster for me to just use GPT here, excuse the lack of personality lol

"Too fast" in this context refers to the operational amplifier's (opamp) speed characteristics, particularly its gain-bandwidth product (GBW) and slew rate. These characteristics measure how quickly the opamp can respond to changes in the input signal.

The OPA828, in this case, has a high GBW and slew rate, which means it can amplify high-frequency signals without distortion. However, this 'speed' can potentially introduce instability and oscillation in circuits that are not properly designed to handle such quick responses. This is particularly true for audio circuits that were not originally designed with such a fast opamp in mind.

Therefore, the comment suggests that unless one has the right equipment (like an oscilloscope) and understanding of the circuit design to control this speed, it may be safer to use opamps from reputable brands offering discrete designs, like Burson or Sparkos. These are likely to be more stable in a wider range of applications.
 
Jul 26, 2023 at 9:39 PM Post #7,296 of 7,383
Faster for me to just use GPT here, excuse the lack of personality lol

"Too fast" in this context refers to the operational amplifier's (opamp) speed characteristics, particularly its gain-bandwidth product (GBW) and slew rate. These characteristics measure how quickly the opamp can respond to changes in the input signal.

The OPA828, in this case, has a high GBW and slew rate, which means it can amplify high-frequency signals without distortion. However, this 'speed' can potentially introduce instability and oscillation in circuits that are not properly designed to handle such quick responses. This is particularly true for audio circuits that were not originally designed with such a fast opamp in mind.

Therefore, the comment suggests that unless one has the right equipment (like an oscilloscope) and understanding of the circuit design to control this speed, it may be safer to use opamps from reputable brands offering discrete designs, like Burson or Sparkos. These are likely to be more stable in a wider range of applications.
Which Sparkos is the best in the size like Burson V5i ?
 
Jul 28, 2023 at 10:46 AM Post #7,299 of 7,383
Hi All!
Hoping to get a little advise here for some rolling. I have a strange DAC, a Line Magnetic LM-32. It's a switchable solid state/tube hybrid, has BALANCED as well as single ended outputs, and the tube section sounds really nice. Anyway, it uses a strange conglomeration of op-amps, 5 in total. I had thought the switchover from tube DAC to SS was exclusive, but after chasing down a static/noise problem, isolated it to a dirty/poorly fitting op-amp in it's socket. That was with Tube DAC selected, not the SS, so obviously the tube amplification selection isn't purely tube.

I'm in process of a major cap mod, including adding film caps to the V+ and V- of each op amp socket for stability. I'll have to confirm this later, but I believe the middle op amp (circled in green) is the only one used in the tube chain.

So 1st, if you look caraefully at the pic, there are two different versions of the 5532D IC's used, two of the JRC version and three of the Cray . Why do you think they used two different iterations of the 5532D op amp? Any difference soundwise between them?

If that single middle op amp is for the tube chain, what do you feel would be a good, detailed but relatively stable op amp to replace it with?

Also, what are your experiences rolling diasy chained op amp stages where subbing for the 5532D? I take it each stage had slightly different design objectives in the chain, and the 5532D was used in both stages for parts commonality/simplicity. I believe each IC is handling one BALANCED channel gain stage. So, in the SS stream, I would like to match towards tube like sound attributes. When I'm not seriously listening, I hope to pull the tubes and only listen to the SS chain and save on tube life. What would you use?

Thanks for any and all replies, and have a great day!!!
 

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Jul 29, 2023 at 5:08 AM Post #7,300 of 7,383
Simple answer is probably thats what they had on hand. Another answer could be that if it isn't a device you owned as 1st owner, someone could have swapped at some point.
As above, i would try opa1656, it is slow enough you don't have to worry about how they've done decoupling on board. And it sounds significantly better.
 
Jul 29, 2023 at 12:59 PM Post #7,301 of 7,383
Simple answer is probably thats what they had on hand. Another answer could be that if it isn't a device you owned as 1st owner, someone could have swapped at some point.
As above, i would try opa1656, it is slow enough you don't have to worry about how they've done decoupling on board. And it sounds significantly better.
Any others you would try at the same time? Would like to get a selection to test.
 
Jul 29, 2023 at 5:29 PM Post #7,303 of 7,383
Any others you would try at the same time? Would like to get a selection to test.
Yes, go for established classics opa1612, opa1642. Discretes are a bit heavy priced, i would add burson v6 duals to the roster, but do try first these cheaper ones. See if you notice something, if you end up liking 1612, go for bjt discrete, if you like 1642 and opa1656 go for jfet (burson v6).
 
Jul 30, 2023 at 5:04 PM Post #7,304 of 7,383
Yes, go for established classics opa1612, opa1642. Discretes are a bit heavy priced, i would add burson v6 duals to the roster, but do try first these cheaper ones. See if you notice something, if you end up liking 1612, go for bjt discrete, if you like 1642 and opa1656 go for jfet (burson v6).
Hi PushTT, appreciate the advise!

Finished the mods to the DAC, and unfortunately, still have the intermittent channel problem, which has gotten worse. Pretty sure it is the loose socket on that center IC, chip is easily removable without prying with just my fingers. Sigh..., its a big ordeal to disassemble again, and DIP socket is going to be a major pain to desolder. For now, it looks like the opa IC adapters from Brown Dog have larger pins, so dropping them in may temp fix problem. It could be the IC as well. So I'm ordering OPA1642's and 1656's w/adapters to test and play with, and will be ordering new 8 pin DIP sockets. If it comes to it, I'll take back apart and replace, but that means several weeks without my DAC.

From what I'm gathering, the sockets need to be machined and not stamped, I'll get those from Mouser, do these look right? Looking for long life with a fair amount of rolling.

https://www.mouser.com/ProductDetail/Mill-Max/210-13-308-41-001000?qs=2fvWSw3gTH8EH6Yn6/PoOA==
 
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