[Ivan TT]

2) At first little "bright" sided but really very clean sound. I wonder if this chip will "calm down" littlebti after some playtime?

Nope, that would be its "signature" sound.
Try AD8066 (NB maximum supply voltage is +/-12V) for same level of details less brightness.

 

[CoiL]

Nope, that would be its "signature" sound.
Try AD8066 (NB maximum supply voltage is +/-12V) for same level of details less brightness.

So, to get it working, I must use potentiometers on both channels or something? I have +-15V power to feed it.
Btw, I left it playing for few days without listening and it seems to be somewhat "tamed".

 

[Rroff]

I wouldn't use potentiometers to drop the voltage - AFAIK you'd have all the problems of a resistor divide with the potential for it to become unbalanced, etc. ideally you'd need linear regulators to drop the voltage but you'd also need some capacitors, etc. if you did that even with the use of something like a LM2940/2990-12 pair.

 

[spacequeen7]

Enjoying this two so far Sonic Imagery Labs 994Enh-Ticha and SS3602

 

[carlmart]

Try AD8066 (NB maximum supply voltage is +/-12V) for same level of details less brightness.

How does it compare, in audio qualities, with the OPA1612?

 

[Ivan TT]

How does it compare, in audio qualities, with the OPA1612?

Better soundstage, better detail and less veil, but bear in mind that I am an AD fanboy
OPA1612 also just a tad harsh to my liking, while 8066 is spot on.
Supply current is x2 higher than OPA, so expect reduction of battery life in portable applications, but most likely 8066 has class AB output stage, nice!

 

[carlmart]

This application will not be for battery powering. Just normal regulated +/-15v or more power supply.

And it will not be to drive a headphone either, but for a DAC's line output. I would prefer to have a class A output too, perhaps with the usual trick of a resistor or ccs, from output to to V+

 

[Ivan TT]

This application will not be for battery powering. Just normal regulated +/-15v or more power supply.

And it will not be to drive a headphone either, but for a DAC's line output. I would prefer to have a class A output too, perhaps with the usual trick of a resistor or ccs, from output to to V+

OK, AD8066 maximum supply is +/-12V
I my case opamps don’t drive headphones directly either (opamps are followed by a buffer), so pretty much the same setup as in line out driving hi-z input.

 

[CoiL]

I wouldn't use potentiometers to drop the voltage - AFAIK you'd have all the problems of a resistor divide with the potential for it to become unbalanced, etc. ideally you'd need linear regulators to drop the voltage but you'd also need some capacitors, etc. if you did that even with the use of something like a LM2940/2990-12 pair.

Yeah, I thought it will not be so easy. Will still go for OPA1612 first and hear the difference between AD8599ARZ and NE5532.

 

[carlmart]

OK, AD8066 maximum supply is +/-12V
I my case opamps don’t drive headphones directly either (opamps are followed by a buffer), so pretty much the same setup as in line out driving hi-z input.

AFAIK, a buffer shouldn't be necessary to drive short cables, from source to preamp or preamp to power amp.

That's why I would like having a chip biased to class A at least, being that all opamps are class AB by internal design. Is there anyone that is not?

 

[Rroff]

While I never looked at crossover distortion, etc. on a scope in this context aside from 1-2 older opamps I've never been able to discern any difference between class AB and biasing to class A (with an advanced cascode) by ear with any reasonably modern opamp.

The AD8066 can be quite veiled in some applications - more so than the OPA1612 IMO but in other applications you can pretty much eliminate 90+% of that especially in circuits that use some form of active ground setup for some reason where the AD8066 seems to benefit - if you really want to hear what the AD8066 is capable of build a pseudo-balanced (or fully balanced) amplifier with an AD8066 per channel in "push-pull" type configuration and drive something like the HD600s via a balanced cable.

While "burn-in" is a contentious one and I don't generally notice it with opamps I do find the OPA1612 appears to benefit a lot from a period of "burn-in" out the box there is a slight harshness and colouration that goes away with use.

For want of a better understanding of it the AD8066 seems to better preserve "directionality" somehow at lower frequencies if such exists in the original music - I don't really understand it but that seems to be somewhere along the lines of what is going on and why it seems to have a subjectively better soundstage than the OPA1612 and gives it a somewhat different bass experience to the average opamp.

 

[carlmart]

I have nothing against headphones, after all they were my most important tool in my recording years, besides the Nagra and the Sennheiser microphones!

But I think a good amplifier + speaker system, on a good listening space, is hard to beat by any headhone in audio qualities.

Rarely do I listen to headphones nowadays, maybe during flying or travelling by bus, so my concern is mostly for line amplification. Demands are less than headphone amps, you don't really need output transistors, besides those inside the IC.

What do you mean by "active ground"? The one you have to make when using single supplies, like batteries?

 

[Ivan TT]

AFAIK, a buffer shouldn't be necessary to drive short cables, from source to preamp or preamp to power amp.

That's why I would like having a chip biased to class A at least, being that all opamps are class AB by internal design. Is there anyone that is not?

I mean in my set up AD8066 drives buffer input, while buffer drives headphones, so AD8066 sees high impedance (similar to line input of a HP amp), not low-z headphones.

These are cool for class-A biasing:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/252135197507

 

[Rroff]

What do you mean by "active ground"? The one you have to make when using single supplies, like batteries?

I'm talking more in the "3 channel active ground" kind of implementation (like the Pimeta https://tangentsoft.net/audio/pimeta2 ) rather than just using an opamp or similar just to set a virtual ground reference though there are a lot of drawbacks especially in terms of noise to that approach but the AD8066 seems to work really well in terms of producing something that is pleasing to listen to even if from an engineering perspective there are a few negatives to the amp design itself.

I built an amp (somewhat along the lines of the PBA https://www.head-fi.org/threads/pseudo-balanced-amplifier-pba.553236 ) that uses one AD8066 per audio channel, with a fully isolated ground per channel, with the headphone drivers sitting across the outputs of the two amps in the package and it takes the AD8066 to another level again.

 

[raoultrifan]

For a very good representation of what active ground means and why would this be better than regular 2-channels headamps, Dr. Meier Corda has a dedicated webpage here: http://www.meier-audio.homepage.t-online.de/grounds.htm.