It is advisable to know what parts do and what properties the part has for that function. The DC servo is not directly in the signal path, QE01 is.
Let the IC socket be and use a low drift opamp for the servo. A stupid idea would be to remove the original IC, solder an IC socket in and remove that one again to solder the original opamp back in. There are better opamps for DC servo function.
The whole point is that the device is not audiophile at all and parts were used not entirely fit for the purpose but then they were pretty standard. Or just cheapest.
Now is the moment to google for "DC servo".
Let the IC socket be and use a low drift opamp for the servo. A stupid idea would be to remove the original IC, solder an IC socket in and remove that one again to solder the original opamp back in. There are better opamps for DC servo function.
The whole point is that the device is not audiophile at all and parts were used not entirely fit for the purpose but then they were pretty standard. Or just cheapest.
Now is the moment to google for "DC servo".
I would use a slow JFET input low drift low offset opamp. You need to learn which one on the list has that properties. Download datasheets and read them. Compare.
It now has a bipolar one. You know what men know about bipolar.
It now has a bipolar one. You know what men know about bipolar.
JUST TO PLAY 'THE DEVILS ADVOCATE' >
If you love the 'sound' of your integrated amplifier and you're not overly concerned about THD, + 'common ground negative' applies,
you can simply use a resistive voltage divider on the speaker output of your integrated amp to drive the input of the power amp.
If you love the 'sound' of your integrated amplifier and you're not overly concerned about THD, + 'common ground negative' applies,
you can simply use a resistive voltage divider on the speaker output of your integrated amp to drive the input of the power amp.
Ai, that really hurts. Both simply bad practice and a safety hazard. Do it with today's devices and things burn.
Completely useless too as OP just created new pre outputs 🙂
Completely useless too as OP just created new pre outputs 🙂
Yes, i did ask but to ChatGPT not Google.
In the era that the air is not clean and cellphone everywhere and every person, even school must bring cellphone.
😆
Here i put the info together from datasheet. These numbers makes me headache 😵
| 4558 | 5532 | TL072 | 2068 | 4580 | 4560 | |
|---|---|---|---|---|---|---|
| Input Offset (mV) | 6 | 0.5-4 | 1 | 0.3-3 | 0.5-3 | 0.5-6 |
| Input Type | OPAMP ❌ | JFET | ❌ | ? | ? | |
| Input Offset Voltage Drift (V/C) | ? | ? | 13 | ? | ? | ? |
| Slew Rate (V/us) | 1 | 8 | 20 | 6 | 5 | 4 |
| Bipolar technology |  | | | | |
I think its safe to put 4558 back? Not all datasheet has JFET information? what to look to find JFET?.
About bipolar, the state that the IC has bipolar technology.
And not all has "Input Offset Voltage Drift"
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Reread post #81 please.
Think, decide, act, verify.
I use the term “JFET” if I look for JFET. I like simplicity 😀 You could also look for “best dual opamp for DC servo” and read the do’s and don’ts.
It is a bit academic but not many would choose 4558 for DC servos today. However you can put the 4558 in the socket and be done with it. It worked well for a long time.
Think, decide, act, verify.
I use the term “JFET” if I look for JFET. I like simplicity 😀 You could also look for “best dual opamp for DC servo” and read the do’s and don’ts.
It is a bit academic but not many would choose 4558 for DC servos today. However you can put the 4558 in the socket and be done with it. It worked well for a long time.
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TL051 is good, and cheap.
https://www.diyaudio.com/community/threads/mr-d-self-why-jfet-opamp-servo.327466/
https://www.diyaudio.com/community/threads/mr-d-self-why-jfet-opamp-servo.327466/
So, i did prepare for testing those ICs. For better objective test, i wrap with paper and put letter, then i write note. One day, one ic, at night. So i just use my memory and ear.
Funny thing is, after all this preparation, i found @Mooly 's thread:
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
So, just for my curiosity, i keep going to the plan.
From all ic, i put extra note in ic C and D, that i feel different from other. Others is just sometimes feel boring, nothing special, nothing different.
The most i feel special is C, i guess maybe 5532 between C or D.
So the result is:
A: TL072
B: 4560
C: 2068
D: 5322
E: 4580
(SKIPED) LM4562
I will test again between 2068 and 5532. Or maybe i should back to 4558 for stability.
I keep all this experience just for learning, fun and curiosity and all this cost around $13 as school fee.
And i skip LM4562 since i read that many user said its not good for older design.
Thank you guys for helping this.
Funny thing is, after all this preparation, i found @Mooly 's thread:
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
So, just for my curiosity, i keep going to the plan.
From all ic, i put extra note in ic C and D, that i feel different from other. Others is just sometimes feel boring, nothing special, nothing different.
The most i feel special is C, i guess maybe 5532 between C or D.
So the result is:
A: TL072
B: 4560
C: 2068
D: 5322
E: 4580
(SKIPED) LM4562
I will test again between 2068 and 5532. Or maybe i should back to 4558 for stability.
I keep all this experience just for learning, fun and curiosity and all this cost around $13 as school fee.
And i skip LM4562 since i read that many user said its not good for older design.
Thank you guys for helping this.
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Pssst! OP249
By now you should have noticed the device itself is nothing special. You can build a much better source selector/volume control yourself. With way less parts.
By now you should have noticed the device itself is nothing special. You can build a much better source selector/volume control yourself. With way less parts.
Since im not an electrical engineering i cannot see its not special device, my finding is that i realized that we cannot just swap the ic. I feel the difference, but for stability sake, i will keep as its original like Mooly's said in his thread.
And that device so special to my ears, from my chain from source to speaker., for all my amps, its still special. Again, its personal preferences.
That may be but you will notice it when comparing side by side. By hearing not seeing. No need to be an electrical engineer. Some of the best dishes are prepared by mothers not cooks.
You can swap the opamps without losing stability, you just did that. There are many that can be used. They won't polish the many (old/corroded?) switches contacts, potentiometers and caps and other stuff away though. You can test this by using only a volume control connected to the power amplifier. Less is more. What is not there can not have an influence 🙂
What I mean is that you can easily build better than that. That is a good emotion, building better stuff yourself. The DIYAudio Mezmerize is a good example that also has no opamps, no global feedback, no switches and no caps in the signal path. All on one board including a PSU, sealed so trouble free relays and enough inputs.
https://diyaudiostore.com/products/mezmerize-b1-buffer
You can swap the opamps without losing stability, you just did that. There are many that can be used. They won't polish the many (old/corroded?) switches contacts, potentiometers and caps and other stuff away though. You can test this by using only a volume control connected to the power amplifier. Less is more. What is not there can not have an influence 🙂
What I mean is that you can easily build better than that. That is a good emotion, building better stuff yourself. The DIYAudio Mezmerize is a good example that also has no opamps, no global feedback, no switches and no caps in the signal path. All on one board including a PSU, sealed so trouble free relays and enough inputs.
https://diyaudiostore.com/products/mezmerize-b1-buffer
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