Current feedback headphone amp with super regulators

In a few days I'm going to get my prototype boards for my headphone amp monster. Meanwhile, what do you think?

http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p1.pdf
http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p2.pdf
http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p3.pdf
http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p4.pdf
http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p5.pdf
http://www.sjostromaudio.com/hifi_files/qrv/qrv08r0schema_p6.pdf

EDIT: Send me a message to get hold of the schematics.

Looks familiar! My version (not the latest revision): [removed]

Breadboard not working yet...

Samuel

Good luck with it. My is already working as QRV06. The difference now is that I have incorporpated a DC-servo and a complete power supply.

Only I and one person more dare to build this monster so I'll guess it stops at two working units.

Could you please elaborate on your super regulator scheme?

It looks to me as tho you have evolved the 'Sulzer-Boberly' notion that I have seen before.

[quote author="peranders"]In a few days I'm going to get my prototype boards for my headphone amp monster. Meanwhile, what do you think?
[/quote]

Mmm.... you sure like to use lots of transistors, don't you? :razz:

Is it all your own design?

[quote author="Carl_Huff"]Could you please elaborate on your super regulator scheme? 

It looks to me as tho you have evolved the 'Sulzer-Boberly' notion that I have seen before.[/quote]
Many names but more like Jung/Didden.

Check here for a little background info

http://sjostromaudio.com/pages/index.php/hifi-projects/142-ssr01-sjoestroem-super-regulator
http://www.e-insite.net/ednmag/archives/1997/010297/01di_03.htm
http://home.comcast.net/~walt-jung/wsb/PDFs/Improved_PN_Regs.pdf

[quote author="cuelist"]Mmm.... you sure like to use lots of transistors, don't you? :razz:

Is it all your own design?[/quote]
BCxxx transistors cost "nothing". The design is in many pieces "basic" with a little "polishing".

Today I'll get the pcb's! :grin:

[quote author="Viitalahde"]I am thinking of a cup of coffee. :razz:[/quote]
I'll guess you read my post without links? You were too fast in commenting. :grin:

But right now i'm going to get myself a cup of coffee, brand "Kahls Kaffe" from Göteborg and the type "Café Inferno".

peranders, what is your reasoning for cascoding the current sources? I know that the impedance dramatically improves, but what overall parameter (i.e. CMRR, THD, PSRR etc.) should get better with this topology?

Samuel

It makes them a bit stiffer and looking very much cooler. :grin:

To be honest, not every detail isn't carefully examined. I desinged the amp and simulated it, made a few changes when I visually saw what certain elements did.

The positive properties is high speed , 10-25 MHz with simple BCxxx transistors and a very low distortion.

I have got the pcb's now. Can't wait to get the soldering iron heated up.

[quote author="peranders"]It makes them a bit stiffer and very much cooler. :grin:

To be honest, not every detail isn't carefully examined. I desinged the amp and simulated it, made a few changes when I visually saw what certain elements did.

The positive properties is high speed , 10-25 MHz with simple BCxxx transistors and a very low distortion.[/quote]

When you cascode you do indeed improve self-heating-induced distortion performance. The voltage swing of the first Q is small, and the effect of temp on alpha is a lot smaller than the effect on beta, so the second Q can have large dissipation shifts with small electrical effects. In some closed-loop designs a given section of the circuit that might be susceptible to this effect will not be, due to feedback. But often in non-inverting configurations, and at the node with the major voltage swings, there can be some significant effects.

Old-timer 'scope amp designers paid a whole lot of attention to these things, as their stuff had to deliver d.c. to f nought performance without response-slowing global feedback.

I don't know how much these types of effects will be visible in a current feedback amp. I use rather small currents and the pcb has groundplane as cooling.

Now you can touch the amp.... :grin: It doens't smoke at least. More reports will follow.

The amp is ready and working, hi hi. :grin:

Is this first headphone amp in the world with quadruple super regulators AND made with SMD parts AND current feedback?

Anyway, I'm real pleased with it.
EDIT: Changed picture link

that looks SO cool!
I must quote someone or other who said "it looks like it sounds good..."
Does it?

chef

/ Beranek's Law:

It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.

L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

Click to expand...

I like the results but since I know a bit I also know what I want. I strive to a certain degree of performance.

I have taken a better picture. The amp works also, pretty good I must add. :grin:

:shock: :shock: :razz:

That beast is simply looking great! I suppose you´ve got some nice headphones also?

Michael

Would be interested in a THD sweep @ 20 dBu and/or a FFT spectrum; any chance?

Samuel