Gyraf Headphone box question

Hi Gyraf,
I'm building some headphone amps, the first run didn't work so well with a 5532 output driver, so I'm thinking of using your output stage... pretty much forward from the 5534 stages IC 4-5 on your drawing... only I'm going to use a +-18v supply cause it's already built.
http://www.gyraf.dk/tmp/Gyraf_headphone_box.PDF

I was digging around and i realize I have a bunch of these NTE55MCPs that I got somewhere these are matched complimentary pairs of power transistors. there are some differences here, but some similarity as well.
The 50watt spec worries me a bit.

Think these will work, or can they be made to work without too many changes?

NTE specs are
Vcbo 150v
Vceo150v
Vebo 5v
Pd 50w
hfe min 40
ft 30mhz min

so you don't have to look it up, here's specs on bd139-140

Vcbo 80v
Vceo 80v
Vebo 5v
pd 12.5w
hfe min 40

Thanks
Kelly

Hi Kelly,

They should work fine - just make sure you get the right pinout..

I've made several of this headphoneamp with BDX53/54's also - I don't think it's chritical about the transistors..

Jakob E.

Hi Jacob
As always, Thanks very much for the input.
:thumb:
Kelly

of this headphoneamp with BDX53/54's

Click to expand...

I originally thought the 4 diode stack was to bias the output devices pretty well, but then I saw those BDX are darlingtons.

So when using BD139/BD140 I figure the stack should use 2 diodes, OK ?

Regards,

Peter

Naa, I just like to run the 139/140's HOT.. :grin:

[quote author="gyraf"]Naa, I just like to run the 139/140's HOT.. :grin:[/quote]
I see, right on, let's burn ! :twisted: :grin:

FWIW, here we have some at 80mA:

http://sound.westhost.com/p24_fig1.gif

I have drawn again the circuit (Gyraf Headphone)
http://us.f1.yahoofs.com/bc/437cd72f_d79e/bc/My+Documents/HeadAmp_sheme.pdf?bfIuNfDBILbvHNNT
Later I shall lay out and PCB

[quote author="Xopek"]I have drawn again the circuit (Gyraf Headphone)
http://us.f1.yahoofs.com/bc/437cd72f_d79e/bc/My+Documents/HeadAmp_sheme.pdf?bfIuNfDBILbvHNNT
Later I shall lay out and PCB[/quote]

Thanks, nice job. :thumb: Nice drawing, which program did you use ?

Just a suggestion, maybe use 'u' instead of 'm' for the cap-values ? Balpark-figures are clear but using 'uF' for microFarads can avoid some confusion later on.

Bye,

Peter

http://sound.westhost.com/p24_fig1.gif

Click to expand...

Sorry for jumping in here, but reminds me of an old Q regarding this type of active gain control: what is the point of arranging the first stage to unity gain and the second to the full desired gain? I'd have distributet gain for several reasons (i.e. noise and distortion), probably even set the second stage to unity gain.

Samuel

Just a suggestion, maybe use 'u' instead of 'm' for the cap-values ? Balpark-figures are clear but using 'uF' for microFarads can avoid some confusion later on.

Click to expand...

Ok... but it's a habit

Nice drawing, which program did you use ?

Click to expand...

The program p-cad...

> when using BD139/BD140 I figure the stack should use 2 diodes, OK?

4 diodes with simple transistors leads to 0.6V/22Ω= 27mA. They are not even running hot. With Darlingtons, you could probably go 6 diodes.

[quote author="PRR"]> when using BD139/BD140 I figure the stack should use 2 diodes, OK?

4 diodes with simple transistors leads to 0.6V/22Ω= 27mA. They are not even running hot. With Darlingtons, you could probably go 6 diodes.[/quote]
Thanks for pointing out, it doesn't heat up quickly I realize now from those figures.

Regards,

Peter

[quote author="Xopek"]

Nice drawing, which program did you use ?

Click to expand...

The program p-cad...[/quote]

All fine, nice clean drawing, there's a certain style to it that gives it the feel of old schematics (good in the case).

BTW, there are a few R-values swapped in your version: R17/R18 & R31/R35 compared to Jakobs original drawing.

BTW, w.r.t. IC4&5 I don't know if the usual compensation caps have been used.

Bye,

Peter

there are a few R-values swapped in your version: R17/R18 & R31/R35 compared to Jakobs original drawing.

Click to expand...

:? uups... it's corrected ....

Just a suggestion, maybe use 'u' instead of 'm' for the cap-values ? Balpark-figures are clear but using 'uF' for microFarads can avoid some confusion later on.

Click to expand...

This same is corrected

BTW, w.r.t. IC4&5 I don't know if the usual compensation caps have been used.

Click to expand...

And it has corrected...

http://us.f1.yahoofs.com/bc/437cd72f_d79e/bc/My+Documents/HeadAmp_sheme.pdf?bfdWefDBpodzPBVH

Hi Xopek,

Sorry to keep nagging you, link as it now is doesn't work.

Thanks again for drawing that circuit.

Bye,

Peter

oh.... sorry
try plz again
http://us.f1.yahoofs.com/bc/437cd72f_d79e/bc/My+Documents/HeadAmp_sheme.pdf?bf97efDBakltPBVH

Works fine now, thanks :thumb:

Doesn't work here. Perhaps the links time out?

Best regards,

Mikkel C. Simonsen

[quote author="mcs"]Doesn't work here. Perhaps the links time out?

Best regards,

Mikkel C. Simonsen[/quote]

It did work for me and I got the file, but I can't repeat that now anymore.

I can send it along or host it myself, but let's first try to fix this at the source, OK ?

Bye,

Peter

I do not know why it has taken place....
Try from here
http://s6.ultrashare.net/hosting/fs/69f125835ae9418f/