Jung Super Buffer

AMZ-FX · Sep 25, 2004

I'm working up a layout of the basic Jung Diamond Buffer and may make some pc boards for this. Anyone else interested in a few?

All TO92 so you can pick your devices...

http://209.124.248.167/media/jung.gif

There are used for preamps and headphone drivers. A discrete unity gain buffer, all Class-A. The pcb is still in the preliminary design phase. The board is 1.25"x1.25" and powered by +/-15v.

regards, Jack

Kev · Sep 25, 2004

YEP

that or something similar has been on my things to do list for so long.

I'm sure I can find some uses for it.
I'm in.

good think tracks and pads and perhaps room for screw terminals
what voltage do you think you will end up with ?

AMZ-FX · Sep 25, 2004

Here's the preliminary schematic:

http://209.124.248.167/media/Jung_Buffer.gif

I'm guessing the boards would be $10 for a set of 3, or $7.50 for two, which includes postage to anywhere in the world... the LEDs glow bright red inside your project...

regards, Jack

Kev · Sep 25, 2004

The board is a bit small for screw terminals

but we might want some mounting holes.
you spec'd the red LED ... not just any LED ??

surface mount resistors ..... :sad:
My eyes might not cope with that.

peterc · Sep 26, 2004

There are some interesting links concerning this design over here :

http://www5.head-fi.org/forums/showthread.php?t=48270

Peter

chrissugar · Sep 26, 2004

I'm also working on this for a while. :grin:

chrissugar

AMZ-FX · Sep 26, 2004

Here is a typical application:

http://209.124.248.167/media/Jung_Buffer2.gif

Be sure to reload the images to see the latest versions...

regards, Jack

Michael Tibes · Sep 27, 2004

This guy has built his superbuffer and sells pcbs, just in case someone doesn't yet know his site: http://home.swipnet.se/~w-50719/hifi/qrv05/index.html
I haven't tried it, it's on my 'ever growing to-do list'. Any listening experience with this type of buffer would be very interesting for me.

Michael

peranders · Oct 14, 2004

Hi!

Not many have built my SMD version of the Jung Buffer but the few who did are very pleased. On the other hand, it's rather hard to fail because this type of buffer is rather uncritical since it's only a buffer. You can "tweak" the performance a bit by choosing the right semiconductors but if you use "rubbish" you will still get astonishingly good results.

StephenGiles · Oct 14, 2004

What are you defining as "rubbish" so I don't fall foul of the "schematic police"!
Stephen

peranders · Oct 14, 2004

Like BC550 and other a couple of cents parts. I think even BC108 will work alright.

Seriously, all 100-300 MHz small signal transistors will do as long as other ratings are OK.

chrissugar · Oct 14, 2004

Welcome to the Lab
You are PerAnders from DIYAUDIO forum, right?

chrissugar

peranders · Oct 14, 2004

Thanks and yes! :grin:

chrissugar · Oct 14, 2004

:grin: :grin: :grin:
:thumb:

chrissugar

jhaible · Oct 14, 2004

[quote author="peranders"]Like BC550 and other a couple of cents parts. I think even BC108 will work alright.

Seriously, all 100-300 MHz small signal transistors will do as long as other ratings are OK.[/quote]

What's wrong with the BC550?

JH.

Flatpicker · Oct 14, 2004

:thumb: Welcome Per-Anders! :thumb:

BTW, what are the "good" sounding transistors? Which SMDs did you use?

peranders · Oct 14, 2004

Nothing really, in most situations but it helps if you know which properties are good and which are not.

peranders · Oct 14, 2004

Flatchecker, you can download all info from my homepage.

I used BC550C/560C in SMD version which is BC850C and BC860C. Cheap and good but they are 100 MHz transistors, according to datasheet at least. BC550C is 300 MHz.

PRR · Oct 14, 2004

Who let you in here, Per-Anders? And welcome! This gang needs a few good theorists with your practical experience.

> Cheap and good but they are 100 MHz transistors, according to datasheet at least. BC550C is 300 MHz.

May not be much different. As I'm sure you know (but others may not), Ft is roughly proportional to current over much of a transistor's range, so the different Ft numbers may just be different test conditions.

Anyway a transistor with β=100 and Ft of "only" 100MHz will have flat β up to 1MHz, which is higher than I can hear. If you are really needing a β of 500 (this amp doesn't need heroic β), then it is still flat to 200KHz. In a circuit with several voltage gain stages and overall feedback outside the amp, that can get you into stability trouble. In an emitter follower (even a 4-transistor follower), with strictly local feedback, it makes nearly no difference in the audio and above-audio bands.

For absolute best performance in the diamond buffer, especially if it swings into Class-B mode, Vbe/Ic linearity is perhaps the most important thing. This isn't often specified, mostly because the Vbe/Ic relation is fixed in the Silicon as long as you stay far below the transistor's maximum current rating. For hi-fi line amps delivering less than 1mA to the load, even 50mA parts are fine. At 600Ω Pro-levels, or headphones, think 100mA-500mA parts (and you probably need the bigger part for dissipation rating as much as for Vbe/Ic linearity).

Dan Kennedy · Oct 14, 2004

I'm using a variation on the theme for the buffers in a 3rd order hi-pass in the EQ, I use 2N4401 and 2N4403's. Cheap and cheerful.

Run 'em warm, not hot, don't short the output.

Put a series R on the input if things are squirrelly.

Jung Super Buffer

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