The "Best" Opamp - Opine Please - Page 3

djk · 27th March 2005, 11:29 PM

You were running a voltage feedback opamp in a current feedback circuit?

I don't expect that from any opamp.

In standard commercial designs, EQs, crossovers, etc, I find the TL072 to be better than the LF353, and the OPA2604 to be a big improvement.

Maybe you should try an AD842, it will drive 100mA and is ~400V/µS (gain=2).

Mr Evil · 27th March 2005, 11:48 PM

Quote:

Originally posted by djk
You were running a voltage feedback opamp in a current feedback circuit?..

Current feedback as in series-derived feedback, not current feedback as in high-impedance feedback node.

m127 · 31st March 2005, 08:14 PM

Hi all,

I've tried to get some OPA 627 opamps here in Hungary for replacements in cdps. The best shop I know here doesn't sell them (nor do ther order), but they sell OPA 27. This is also a single opamp, should be very similar to OPA 627, maybe somewhat weaker. It comes at about EUR 2,50. Have you tried this? Do you recommend it?

One of my players I like the best is an Onkyo DX-6870 integra R1. It has eight pieces of dual opamps in the analogue board, quite a lot, isn't it? This means, if I want to use brown dog converters and single opamps then I will need 16 pieces of them! This is once more the same amount of money than what bought me the player itself. Unfortunately I don't have the schematics, so I cannot tell which opamp is doing what. They are all 5532s, I guess I should consider replacing all of them. Can anybody give me some advice? Which opamp is which stage, what to replace and what I should use?

Gasho · 31st March 2005, 08:31 PM

You can use AD826 in all places. It is dual like NE5532 , it´s super fast , itś musical , an far better than BB.

amplifierguru · 1st April 2005, 12:24 AM

I have used many chips from the LM301AN with 2pole comp in my early active crossovers, mixers and full preamps in the 1970's throughLF 351's to OPA637 chip driven power amplifiers in 1990's.

In 1994, I designed a chip driven nested feedback 200W power amplifier sufficiently forgiving that I could plug in a variety of 'contenders' and we (all the golden ears at the company I was designing for at the time) auditioned them. We tried NE5534,AD845,LF357,and OPA627.
Tested at 80Wrms output all produced 0.008-9% THD (80Kbw) at 1KHz and between 0.0017% and 0.0025% at 20KHz.

The clear winner was the OPA627 while the worst sounding (dark) was the NE. It had the lowest THD at 20KHz.

But the NE5534 are excellent for power supplies.

thorstenlarsen · 4th April 2005, 08:54 PM

Hi m127 !

You might be able to get free samples of BB op-amps at www.ti.com. I did.

Thorsten

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27th March 2005, 11:29 PM	#21
djk diyAudio Member Join Date: Feb 2001 Location: USA	You were running a voltage feedback opamp in a current feedback circuit? I don't expect that from any opamp. In standard commercial designs, EQs, crossovers, etc, I find the TL072 to be better than the LF353, and the OPA2604 to be a big improvement. Maybe you should try an AD842, it will drive 100mA and is ~400V/µS (gain=2).

31st March 2005, 08:14 PM	#23
m127 diyAudio Member Join Date: Mar 2004 Location: Budapest	Hi all, I've tried to get some OPA 627 opamps here in Hungary for replacements in cdps. The best shop I know here doesn't sell them (nor do ther order), but they sell OPA 27. This is also a single opamp, should be very similar to OPA 627, maybe somewhat weaker. It comes at about EUR 2,50. Have you tried this? Do you recommend it? One of my players I like the best is an Onkyo DX-6870 integra R1. It has eight pieces of dual opamps in the analogue board, quite a lot, isn't it? This means, if I want to use brown dog converters and single opamps then I will need 16 pieces of them! This is once more the same amount of money than what bought me the player itself. Unfortunately I don't have the schematics, so I cannot tell which opamp is doing what. They are all 5532s, I guess I should consider replacing all of them. Can anybody give me some advice? Which opamp is which stage, what to replace and what I should use?

31st March 2005, 08:31 PM	#24
Gasho diyAudio Member Join Date: Nov 2004 Location: Zagreb	You can use AD826 in all places. It is dual like NE5532 , it´s super fast , itś musical , an far better than BB.

1st April 2005, 12:24 AM	#25
amplifierguru Account Disabled Join Date: Aug 2004 Location: Earth	I have used many chips from the LM301AN with 2pole comp in my early active crossovers, mixers and full preamps in the 1970's throughLF 351's to OPA637 chip driven power amplifiers in 1990's. In 1994, I designed a chip driven nested feedback 200W power amplifier sufficiently forgiving that I could plug in a variety of 'contenders' and we (all the golden ears at the company I was designing for at the time) auditioned them. We tried NE5534,AD845,LF357,and OPA627. Tested at 80Wrms output all produced 0.008-9% THD (80Kbw) at 1KHz and between 0.0017% and 0.0025% at 20KHz. The clear winner was the OPA627 while the worst sounding (dark) was the NE. It had the lowest THD at 20KHz. But the NE5534 are excellent for power supplies.

4th April 2005, 08:54 PM	#26
thorstenlarsen diyAudio Member Join Date: Jun 2004 Location: Copenhagen	Hi m127 ! You might be able to get free samples of BB op-amps at www.ti.com. I did. Thorsten

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