Looking for a high-end DiY headphone SS amp

[BucketInABucket]

As the title says, I'm looking for a DiY headphone SS amp project on a level comparable to the AMB B22 and Dynamight amps to go along with my DiY DAC project. Suggestions please, as I'd like more options

 

[rol]

QRV08 if you could manage the soldering work.

 

[BucketInABucket]

I've had a look at that. I'm decent with an iron but don't know what parts to go for.

 

[rol]

Parts for the QRV08 are pretty simple and can be sourced from either Mouser or Digikey. This is a very underrated truly high-end headamp.

 

[BucketInABucket]

Do I simply look at the schematic and see what parts I need that way? There doesn't seem to be a parts list anywhere on the website for me to refer to.

One advantage of the board is that it seems to be very tiny, that's for sure. Wonder if one or two can be put into balanced mode while still accepting single-ended inputs?

 

[HotIce]

IMHO, the only reason to go into such esoteric circuits, is if you are designing it yourself, and you like that aspect of the build.
For something you want to simply build, which has a very good sound, I would suggest The Wire.
It is tiny, cheap, and sounds wonderfully.

 

[BucketInABucket]

Would the wire be able to rival the B22 or dynafet? I am designing the entire enclosure from the ground-up for myself to accompany my DAC so I'd like a similarly great totl amp section to be inside it.

 

[HotIce]

Rival, in terms of hype, or sound? For the latter, yes, I think so.
I am currently using a commercial portable amp which, though not The Wire, it is based on the same circuit (OPamp VAS with diamond buffer IC within the FB loop), and although I tried many SS others, I could not tell the difference.
But I cannot also tell the difference from a $1000 cable, from a 10$ one, so my hearing might be impaired

 

[BucketInABucket]

In terms of sound of course, not hype. I don't really care for hype but the side-product of it is that those are the two that most come up in google search functions. It's also the reason I posted here as I wanted to know the full range of options at the very top and it seems to be a lot simpler to make than the Per Anders offering!

What I am a little concerned with is how to get the boards and which ones do I need to get if I want both balanced and single-ended input and output.

 

[HotIce]

There is a thread in the HP section, where I believe the author is selling PCBs for them.
Such thread is also your best bet to ask further information.

 

[BucketInABucket]

Thanks. I'll take a look and then see what other options I have.

 

[rol]

Just send Sjostrom Audio and he will forward you the schematics and BOM. Keep in mind that the B22, Dynamite and QRV08 are all discrete, while the Wire is not. Buget for them are also vastly different. Someone must be out of their mind to call the B22,Dyamite or QRV08 'hype'.

 

[jcx]

for what headphones?

 

[BucketInABucket]

Just send Sjostrom Audio and he will forward you the schematics and BOM. Keep in mind that the B22, Dynamite and QRV08 are all discrete, while the Wire is not. Buget for them are also vastly different. Someone must be out of their mind to call the B22,Dyamite or QRV08 'hype'.

They are hyped. Not that much compared to a lot of commercial offerings but when the B22 and dynamite especially are compared to other offerings in the DiY world, there's a big difference.

 

[BucketInABucket]

for what headphones?

Orthos mainly, which require plenty of juice.

 

[jcx]

the Vswing can be a limitation if you think you need 5-10 Wrms into 50 Ohms, low sensitivity orthos

the B22 can't swing at all close to its rails despite its current output ability

typical op amp based amps would have to be bridged to get near the V

power dissipation, heat removal from even most unity buffer IC is beyond the project amps I've seen

I have done it but its not at all ready for others to try and access to a machine shop helped too:

6x TPA6120 dual op amps, rated 400 mA each op amp - parallel pairs biased against each other for Class A push-pull output (a little over 200 mA Class A bias for the headphone amp)

this is sized as a headphone amp so the outputs are cascaded for higher drive V (600 Ohm cans or the insanely low sensitivity AKG K1000)

TPA has exposed Cu power pad meant to be soldered to board for several W dissipation, by soldering "belly up" I contact them to the Cu slug of a pc cooler - running ~ 30 W quiescent total without fan

re arranging the I,V by flat paralleling you could get 2.4A, 15 V peak each channel for ~ 14 Wrms into 8 Ohms Class AB stereo

all up, both channels paralleled as a monoblock the shown components, heatsink should drive down to ~3 Ohms

 

[BucketInABucket]

Damn that looks like a fabulous amp. Nicely made, especially the heat sink.

Anyways, since the wire has configurable gain settings it seems to be the one I should go for at the moment.

 

[pidesd]

suggestions....

maybe:

-f4 with reduced bias

-aca amp with reduced bias

-sewa amplifier(no gain) with irfp240 or other

DAO buffer (by EUVL)

I've have a beta22 and thought it was very good.

Right now i'm listening to a sewa with irfp240 and recduced bias and it sounds VERY transparent

 

[HotIce]

Orthos mainly, which require plenty of juice.

What are the specs for your current HP?
The LME49600 buffer can drive 250mA (450mA peak - silicon limited) sustained, but power dissipation comes into play.
If you are mostly driving low Z HPs, I would set the rails +/-V to lower values to ease dissipation.

 

[BucketInABucket]

I have a pair of Yamaha HP-1 Anisotropics:

Impedance: 150 ohms
Sensitivity: 96dB/mW
Rated input: 3w
Max input: 10w

And a pair of NAD RP18 Kaptons:
Impedance: 50 ohms
Sensitivity: 94dB/mW
Max input: 200mW

I also have a pair of K7xxs which don't need quite as much power as those two so I won't post the specs.