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visualwang 8th November 2006 01:33 PM

In Active crossover application, OPA2134 and OPA2604, which is better?
I found that these two ICs had similar parameter, but some difference:

OPA2134: lower noise(8nv, 2604 is 10nv), lower distortion(0.00008%, 2604 is 0.0003%);

OPA2604: high slew rate(25v/us, 2134 is 20V/us), high bandwidth(20M, 2134 is 8M)

In Active Xover, there are input buffer, filter, output with gain changing. Input buffer and filter are all unit gain.

Then, 2134 and 2604, which is better? Or have other ICs be more fitable in this situation?

Thanks in advance!

darkfenriz 8th November 2006 01:37 PM

If you are going Sallen-Key filter, that's not much difference, because all op-amps work as followers. I would choose opa2134, because 2604 is known to have much higher THD in reality than its spcs suggest.

PierreG 8th November 2006 01:44 PM

What schematic are you using?

visualwang 8th November 2006 01:57 PM


Yes, I use Sallen-key architecture and 4rd L-R filter. Its a two-way system with input buffer and gain ajustable ouput buffer.

I know there is little difference between these two OP, but I want to know which is better.

Actually, 2604 is a little expensive than 2134. If 2134 is better here, I would like select 2134.

ingrast 8th November 2006 05:59 PM


Originally posted by visualwang
Actually, 2604 is a little expensive than 2134. If 2134 is better here, I would like select 2134.

May want to check LM4562 ....
0.00003% THD
2.7 nV

Just received 3 free samples today.


Nelson Pass 8th November 2006 06:21 PM

When we were developing the XVR1, I prototyped the
circuit with 2604's, and it did not sound good. I attributed
it to instability in the op amp when used near unity gain.


georgehifi 8th November 2006 07:12 PM

2 Attachment(s)
I 've tried them all at least half a dozen of the so called high end opamps in this circuit, and the OPA4134 was the best sounding, but still not good enough for me for the mids and tops just for the bass, the mids and tops were better when passivly done still. And as Nelson stated when trying different ones be sure they are unity gain stable before getting them.

Cheers George

mlloyd1 8th November 2006 07:36 PM

i think the opa2604 is (at least designed to be) unity gain stable - no minimum gain requirement, such as the OPA637 has.

i think Nelson was pointing to something else in the design/operation of OPA2604?


clem_o 9th November 2006 02:39 AM

In a test that I did with my KEF Kube (a low-frequency active equalizer for older KEF loudspeakers) the 2134s sounded more neutral and less strained than the 2604s. The original ICs are NE5532s BTW.


lineup 9th November 2006 03:01 AM

OPA2134 and OPA2604
are very close in data.
It is difficult to say which one is better.
I would say it depends on what circuit.

OPA2604 is a little bit faster. +Gain Bandwidth.
OPA2604 is one of the few op-amps having +24 -24 max supply voltage.

OPA2134 is more stable, as it is not too fast for Audio.
OPA2134 is more used and more liked, than almost any other JFET op
( Maybe still TL072 is most used, but it is far from OPA2134 in quality )


OPA2134 is probably the most used DIY Audio op, all categories.
It is has good qualities and very all-round
so almost never any problems, whatever type of circuit or gain.
Has very good current drive capability for being an OP-amp.
Close to a perfect OP for general Audio designs.

Unless you need that high +24V -24V supply
I would say you buy a supply of 10-20 OPA2134.
They can be good to have at home,
whenever you want to setup some circuit.


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