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What is your favourite opamp ?

Mogami Cables

psychotropic

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can someone explain to me what op-amps do? none of the explanations i've read on the net give me a good clear "complete idiot's" explanation on what they do and especially in the context of audio components. I do know they are amplifiers of some kind, but very little beyond that. Do they just amplify the audio signal by a little bit here and there within the components? why are they there? how do they work?

thanks in advance!
 

murali_n

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Hai,

I have replaced the OP074 opamp in my NORGE with OPA 2134 ICs.

In Marantz CDP 48 have replaced the OPAMP 4560 with OPAMP 4562, which gave very good transparency and improved the placement of instruments in the sound.

N.Murali
 

cha_indian

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I replaced NE5534 in my cd player to a Audio GD Sun V2 and after burn in, it sounds better than OPA627 :) NE5534 was actually degrading SQ in my cdp. The SQ improved a little when there was no opamp .

cranky, what is inverting and non inverting ? and one more thing, what is power opamp?
 

spirovious

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Well, now how to choose a proper OPAMP?
Is it possible to improve AVR SQ by replacing them?
 

linuxguru

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Among the cheap opamps, the sub-Rs.10 NE5532 has excellent sonics as long as the output swings are at line level (1V peak) or lower, and into relatively high impedance (1k or higher).

At the high end, the NatSemi LME49710/49720/49740 (LM4562) family has impressive specs - and are generally the best for almost all applications except as a low-gain or unity-gain buffer. However, be prepared to shell out anywhere from Rs.400 - Rs.1200 each.

Between these two extremes, Linear Technology makes some excellent high bandwidth opamps in the $5 range. My current favourite is the LT1208 (45 MHz, 400 V/usec), but there are at least a couple of dozen other LT opamps that are serious contenders. The LT1208 is extremely clean and transparent - however, it may not work out well as a drop-in replacement for older op-amps because of its extreme slew-rate, which can cause ringing and other artifacts in existing designs.

IMHO, in a well-designed circuit the LT1208 comfortably beats the LM4562 on audible sonics.
 

hemantwaghe

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Second "idiot" question?
Is soldering involved in changing opamps? Or it is just changing standard chip??
 

murali_n

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Hai Hemant,

In Amps the Opamp ICs are soldered in the PCB. If you want to experiment with different Opamp ICs then try fixing a IC base, of 8 pin which will be convenient. I have done this in my NORGE. You can swap Opamps with ease until you settle for a good sounding one.

N.Murali
 

kaushik

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Where does the burson audio op-amps stand ?


They are just hype or fully worth the money.
 

linuxguru

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Burson makes a bunch of discrete op-amps and buffers. They're built on a small PCB with discrete components and are meant to be drop-in replacements of well-regarded monolithic opamps like the Burr-Brown OPA-2604, OPA-2227, and various others.

IMHO, they're mostly hype and it is very difficult to beat state-of-the-art monolithic op-amps like an NatSemi LME49720 or Linear Technology LT1208 on measurable performance.

If you want to try them out, try using a socketed circuit which allows swapping op-amps. It will become immediately clear that there are a huge number of commercial monolithic op-amps that are vastly superior to over-hyped discrete op-amps like the Burson.
 

gobble

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I have basic question - when does one use single opamp and when do we use dual? I was thinking of the Burson opamp as an upgrade path for the Xonar ST. Are their any other better ones out there that are more cost-effective?

Regards
 

kaushik

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I have basic question - when does one use single opamp and when do we use dual? I was thinking of the Burson opamp as an upgrade path for the Xonar ST. Are their any other better ones out there that are more cost-effective?

Regards
If you are replacing then replace with the type one that was there single /dual (dual is just 2 op-amps in 1 pack ;) )..
2 single can be used in a dual op amp place if space is there .
A daughter board and smd chips can be used to support
a dual with 2 single opamps.
 

cha_indian

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Why is that you have two opamps for a single channel. My DAC has NE5532 and OPA604 for a single channel. The user guide states that we can replace NE5532 for LM4562 and 604 to 627/637...

NE5532 is a "power opamp" according to the seller......was wondering what is that ...
 

gobble

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If you are replacing then replace with the type one that was there single /dual (dual is just 2 op-amps in 1 pack ;) )..
2 single can be used in a dual op amp place if space is there .
A daughter board and smd chips can be used to support
a dual with 2 single opamps.

That is common sense. My question should have been - "What is a dual opamp and where is it used or preferred over single opamp?"

Cheers
 

sachi

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Why is that you have two opamps for a single channel. My DAC has NE5532 and OPA604 for a single channel. The user guide states that we can replace NE5532 for LM4562 and 604 to 627/637...

NE5532 is a "power opamp" according to the seller......was wondering what is that ...

Am guessing the OPA604 is being used as a DC servo..highly recommend you go with something that has a low input offset voltage spec. I've found the OPA2227 to be superlative in this role. Replaced the OPA604 in my own DAC with these. Instantly I could hear better black levels, better extension on both ends of the freq spectrum. Much cleaner.
 

linuxguru

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Why is that you have two opamps for a single channel. My DAC has NE5532 and OPA604 for a single channel. The user guide states that we can replace NE5532 for LM4562 and 604 to 627/637...

One op-amp may implement a filter, probably with some gain, while the second may be a unity-gain buffer. The optimal op-amps for the two functions may be different - the LM4562 is extremely low-distortion, but with high loop-gain. It's not really great as a buffer, for which other op-amps work better.

NE5532 is a "power opamp" according to the seller......was wondering what is that ...

That's a bizarre claim. The NE5532 works best at line-level amplitudes and into high-impedance loads. It's a great op-amp for that function and price, but it's no power op-amp...
 

sachi

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Impossible to advise without a schematic as need to ascertain certain things in the circuit.

Don't think he has one..this must be for the DAC he just finished troubleshooting.
Only two possibilities, the OPA604 is either being used for the I/V or for the buffer(high chance its for this). Don't remember seeing 3 opamps per channel on that particular DAC of cha_indian's.
 

IndianEars

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psychotropic


can someone explain to me what op-amps do? none of the explanations i've read on the net give me a good clear "complete idiot's" explanation on what they do and especially in the context of audio components. I do know they are amplifiers of some kind, but very little beyond that. Do they just amplify the audio signal by a little bit here and there within the components? why are they there? how do they work?

thanks in advance!

Though there have been 2 answers to this (and its related ) question, I would like to give it a shot myself.

An Op-Amp is an abbreviation for 'Operational Amplifier'.

It is a pre-designed circuit aimed to be used as a basic amplifier for practically ANY application.

It consists of 1 output and 2 inputs.

The inputs are Non Inverting and Inverting.

The inverting input, 'reverses the signal before amplifying it. By reversing, I mean when the input goes Positive ( say from Zero to +1, the Output will go negative ie o to say Minus 10. Here the gain will be -10)

The characteristics of an IDEAL Op Amp are:

1. Infinite gain ( ie a gain of 100000...00000 ! and Gain is How many times the output is greater than the input)

2. Infinite Bandwidth ( DC to Zillion Megahertz )

3. Infinite Input impedance ( ie draws almost Zero current from its input signal )

4. Zero Output Impedance... ie delivers as much output current as you need

REAL WORLD OP AMPS
The 741 was one of the early, VERY popular op amps... circa 1970s

The actual specs of the 741 were approx:

1. GAIN: 100,000 (60 dB)

2. Bandwidth DC ie 0 for full Gain and then the gain begins falling with frequency, SOON after a few Hertz.

3. output could provide about 50 milli Amps ( 1000 milliamps = 1 Ampere current)

There is a KEY to Op Amps.

Their Gain x Bandwidth = Constant

Hence if the 741 op amp had a gain of 100,000 @ 10 Hz, it would have a Gain of only 100 at 10,000 Hz ( ie 10 KHz) and a gain of just 1 at 1 MHz ... Not so ideal after all !

The trick is "feedback'

By applying feedback (requires just 2 resistors, each costing a few paise) , you can operate the Op Amp at whatever gain you want, and change ( extend) its bandwidth and other characteristics.

Whew... If you are with me so far, the sermon is almost over.

Just as there are horse for courses, there are many different Op amp, each created to specially excel in one task, often at the costy of another task.

For example you could have an Op Amp that will deliver LOTS of output current ( eg for long cables) but will not be 'fast' and may not provide an extended frequency response.

In such cases, a good designer may split the audio processing over 2 stages, and use 2 different Op amps, that are best suited to their individual roles.


A Power Op Amp is typically an Op Amp that can deliver a LARGE amount of power, such as driving a Servo Motor or even a Loudspeaker directly.

IMHO, the 5534 is Not a Power Op amp. It can deliver about 50 milli Amperes of current, while a true Power Op amp will deliver 1000 milli ampere or more of current.
 
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kaushik

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That is common sense. My question should have been - "What is a dual opamp and where is it used or preferred over single opamp?"

Cheers

what it is i told already !
Reasons of choosing dual are saving board space and component cost.
A dual op-amp cost less than two single in many cases.

But single op-amps give design flexibility providing offset null and external frequency compensation pins etc.
 
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