Current feedback headphone amp with super regulators

[peranders]

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.

 

[Samuel Groner]

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

Breadboard not working yet...

Samuel

 

[peranders]

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.

 

[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.

 

[cuelist]

[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?

 

[peranders]

[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

 

[peranders]

[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:

 

[peranders]

[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".

 

[Samuel Groner]

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

 

[peranders]

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.

 

[peranders]

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

 

[bcarso]

[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.

 

[peranders]

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.

 

[peranders]

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

 

[peranders]

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

 

[Swedish Chef]

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

chef

 

[peranders]

/ 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.

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

 

[peranders]

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

 

[Michael_Hartlieb]

:shock: :shock: :razz:

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

Michael

 

[Samuel Groner]

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

Samuel