The Opamp thread

[DarkZenith]

You can use MUSES03 in a lot of amplifying implementations as said in data sheet : "The MUSES03 features high quality sound, low input bias current, low noise, ultra low distortion and high slew rate, and it is suitable for I/V converters, preamplifiers, active filters, headphone amplifiers, and line amplifiers."
I put two at the gain stage of an iBasso P5 Falcon and they're working great, with a clear and punchy sound, very accurate and "musical" at the same time, without any harshness.

 

[SpudHarris]

Just pulled the trigger on 2 x muses 3 from Audinst on EBay. They have great feedback and I am familiar with some of their products so fingers crossed its all legit...

I still keep coming back to OPA2209... No matter what I listen to nothing (yet) seems to grip me like the 2209. The musicality, depth and resolution especially with electronica is just amazing. Can't help but wonder how much better the Muses03 will be considering the cost difference.

I'll report back when Muses03 arrive...

 

[nesty]

Guys, is there an op amp that has the signature sound of an SS3602 sparkos? thanks

 

[nesty]

Got everything soldered up now so will be testing OPA2209 this evening... Sorry for the poor quality ipad pics.

Hi @SpudHarris , may I ask what are those resistors for? thanks

 

[SpudHarris]

Hi Nesty, they are a tweak for class A biasing. That module is for dual Opamps.

 

[endia]

Hi Nesty, they are a tweak for class A biasing. That module is for dual Opamps.

Hi @SpudHarris, why not to use a crd (ie 1n5298 a la MINT) since current will be vary with the signal in a resistor bias which means not a real bias..

 

[nesty]

Hi Nesty, they are a tweak for class A biasing. That module is for dual Opamps.

Hello @SpudHarris , just asking is that required for opa2209 because I thought it is plug in straightforward. Btw, how did you compute the values and which pins of the opamp are the resistors connected. thanks

 

[Rroff]

How do people find class A biasing? one of my amps has a dual jfet cascode and aside from 1-2 older op amps I've never noticed a difference - not scoped it ever to see what impact there is on crossover distortion but a lot of modern op amps kind of take care of that anyhow.

 

[raoultrifan]

http://www.eandiltd.com/pdf/class_a_vs_class_ab.pdf and https://www.sweetwater.com/forums/showthread.php?26210 explain pretty well the differences between Classes A and AB.

However, it would be interesting to compare distortions of an Class-A biased opamp vs. the same opamp but not-biased, of course...used in exactly the same config.

 

[nesty]

http://www.eandiltd.com/pdf/class_a_vs_class_ab.pdf and https://www.sweetwater.com/forums/showthread.php?26210 explain pretty well the differences between Classes A and AB.

However, it would be interesting to compare distortions of an Class-A biased opamp vs. the same opamp but not-biased, of course...used in exactly the same config.

thanks very informative. Question: is it audible between biased and unbiased?

 

[raoultrifan]

Technically speaking, THD differences between class-A and class-AB are measurable indeed, but shouldn't be quite audible...well, unless someone with golden ears is around.

 

[FritzS]

Technically speaking, THD differences between class-A and class-AB are measurable indeed, but shouldn't be quite audible...well, unless someone with golden ears is around.

The difference are only TIM and Crossover Distortion. But they are measurable and hearable in Class AB Diamond buffers (Walt Jung) - discrete or IC (looks like BUF634, LME49600, LME49610, LMH6321, ....)?
The most buffers have a Quiescent Current more than 15mA in wide bandwith mode (BUF634). This will drive the most headphones in lower hearing levels in Class A.
Two buffers in parallel they have 30mA Quiescent Current.

https://en.wikipedia.org/wiki/Crossover_distortion
https://electronics.stackexchange.c...es-and-capacitors-reduce-crossover-distortion
http://www.aikenamps.com/index.php/what-is-crossover-distortion
http://abacus-audio.org/files/akademie-6.pdf
http://www.jockohomo.net/data/7470.pdf

 

[raoultrifan]

I've seen myself the 3rd harmonic lowering just a little bit when setting the BUF634 to wide-mode, most likely IMD decreased a bit too (haven't measured it across entire spectrum), however PASSLAB explains it pretty well here: https://www.passlabs.com/press/leaving-class.
And I also agree with their answer: https://www.passlabs.com/press/class-or-class-ab-classless-society, mostly because usually choosing a good PSU and the right components is more important that biasing into class-A.

However, looking forward to see some measurements of a regular opamp vs. the same, but biased into class-A. It would be quite interesting to find a good candidate, especially if used in I/V, LPF or voltage-gain.

 

[martist]

Maybe a dumb question. Is it possible to put the NE5534 in the place of the lme49710?

The stock opa is the lme49710.

The way around is possible, i read everywhere.

Like earlier said. Just for fun , i want to know if i can hear better or worse audio.

 

[raoultrifan]

Well, some might say it's a downgrade...and if you look at their datasheets then LME49710 could be a better option.
What's your device, please?