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Old 24th November 2006, 02:18 AM   #1
K-amps is offline K-amps  United States
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Default Op-amp for signal inversion.

Do you guys have any favorites? I used to use the TL082's for inverting one channel to bridge the amp... are there any better (dual) op-amps out there for this purpose (i.e. unity gain/ low THD etc.)

Thanks.
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Old 24th November 2006, 03:41 AM   #2
jcx is offline jcx  United States
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hoe accurate do you need - post#1 here:

High loop Gain Composite Op Amp Circuits

is likely to give unmeasurable audio frequency distortion
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Old 24th November 2006, 04:30 AM   #3
K-amps is offline K-amps  United States
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Thanks JC, but I needed a simple recommendation of a unity gain inverter... no need for buffers etc.

The application is to bridge a power amp, so I need one channel inverted and the other non-inverting pass through.
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Old 24th November 2006, 07:05 AM   #4
ACTIVA is offline ACTIVA  Singapore
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Some nice unity gain stable dual Op-amps for audio just to name a few...
OPA2604, OPA2134, OPA2132, OPA2107 (expensive), NE5532(cheap), TL072 (cheap), AD712 etc.

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Max
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Old 24th November 2006, 08:01 AM   #5
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Or just use a DRV134 to drive both sides, it should have much lower overall distortion as it is internally trimmed so you don't get differences between channels that you would if you just inverted one with an opamp.
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Old 24th November 2006, 01:33 PM   #6
K-amps is offline K-amps  United States
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Quote:
Originally posted by ACTIVA
Some nice unity gain stable dual Op-amps for audio just to name a few...
OPA2604, OPA2134, OPA2132, OPA2107 (expensive), NE5532(cheap), TL072 (cheap), AD712 etc.

Regards
Max

Thanks Max,

Since I will be buying just a couple, price is not a factor where I have spent over $200 in upgrades already.. don't want to screw it up by saving a few cents and making the effort less rewarding.

How would you compare the sound of the OPA2604, 2134 and 2107?

By the way how's the AD979?
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Old 24th November 2006, 01:34 PM   #7
K-amps is offline K-amps  United States
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Quote:
Originally posted by pinkmouse
Or just use a DRV134 to drive both sides, it should have much lower overall distortion as it is internally trimmed so you don't get differences between channels that you would if you just inverted one with an opamp.

Pinky have you heard this baby before? Seems like the practical approach...
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Old 24th November 2006, 02:27 PM   #8
lineup is offline lineup  Sweden
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OPA2134 is a fair price and very good audio op.
Unity gain, non-inverted or inverted
and the distortion will be practically zero.

With a good normal regulated dual voltage supply.
+-15 Volt is the recommended.

OPA2134 has several useful features,
that contributes to make it the main stream audio op of today
:
- It is stable in unity gain.
- JFET input. You can use higher input impedance input resistor, if you like.
- OPA2134 has good high current output for driving lower loads.
- Easy to find most everywhere. You can compare price from many dealers.
- Buy at least 10 pcs and put in your good-to-have-at-home shelf.



For a unity gain line level buffer, I can't see any problems selecting an operational amplifier.
Several other more simple op-amps, would do very well at gain=1.
This is the most easy job, at least with reasonably normal input impedances
and normal load impedances.
This is also why a single transistor follower can do this buffering
many times with as low distortion it is hard measure.


It is when task is voltage amplification, say >=5 and maybe x20-100,
when we can start bothering and try to find the most suited op-amp.

lineup
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Old 24th November 2006, 02:48 PM   #9
K-amps is offline K-amps  United States
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Thanks line-up. Are these prone (more than others) to noise/hiss etc i.e. are they picky or happy -go-lucky :-)
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Old 24th November 2006, 02:57 PM   #10
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Quote:
Originally posted by K-amps
Pinky have you heard this baby before? Seems like the practical approach...
Use 'em all the time. Bypass power rails with a low ESR 10uf electrolytic and a 0.1u plastic and you'll never even hear them.
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