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Old 19th April 2006, 12:31 PM   #1
Lyra is offline Lyra  Norway
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Question OP_AMP...replacement...?

I've got a Phoenix Gold QX4150 4 ch. car-amp and this are using the "old" HA4741 op-amp in the input/ filter stage.
The sound from this amp is so and so...

Considering the "741-family" not very good for audio-use, I want to replace theese op-amps...

I was thinking about MC33079. I can get theese from SGS-Thomson, and ON-semi, would the manufacturer have an inpact on the sound ?

Is there any other Quad op-amp's available that would be better than the MC33079 ??

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Old 19th April 2006, 06:25 PM   #2
Perry Babin is offline Perry Babin  United States
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Unless the old op-amps have failed, don't look for a significant change in the overall sound of the amp. You may get slightly less noise but there should be no change in sound.

I've used both the MC33079 and the OPA4227. The 4227 has lower noise figures but is not always a good direct replacement due to instability in some circuits. If you don't have an oscilloscope to check for oscillation, I would suggest that you use the 33079.

Don't use the OPA4228 in a buffer or filter circuit. It's a good op-amp but it is not stable in a unity gain circuit.
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Old 19th April 2006, 10:15 PM   #3
Eva is offline Eva  Spain
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MC33079 is a quad version of LM833 and it's quite a good low-noise op-amp for its price (it's also available as "LM837").

Anyway, there are thousands of op-amps that will show better specs on paper than a 741. You could even just put a TL074 as well... But, is a change really required?
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Old 21st April 2006, 07:16 AM   #4
Lyra is offline Lyra  Norway
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....required....I don't know...but my thoughts was "no chain is stronger than the weakest link"...and in this equation the 741 is the most likely weak link...

I like the sound of the old 5532...what is the nearest quad-equivalent similar to this ?

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Old 21st April 2006, 07:31 AM   #5
tschrama is offline tschrama  Netherlands
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the OPA227 series is my favorite opamp these days... the outperform the OPA627, AD797, NE5534, LT1007 in terms of THD and noise..
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Old 22nd April 2006, 07:24 AM   #6
cartman is offline cartman
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I have 4pcs OPA227 in cermaic socket - have you datasheet for this?

My other question:

I found 2pcs LM833N OPAs in my Philips CD940 CD-player, and I don't know this OPA.
What is the best recommended OPA instead of this LM833N for improvement?

Thx in advance!
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