Gyraf Headphone box question

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Sleeper

Well-known member
Joined
Jun 6, 2004
Messages
649
Location
Los Angeles
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.
 
of this headphoneamp with BDX53/54's

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
 
[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:
p24_fig1.gif

http://sound.westhost.com/p24_fig1.gif
 
http://sound.westhost.com/p24_fig1.gif
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.
Ok... but it's a habit :)

Nice drawing, which program did you use ?
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 ?
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.
:? 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.
This same is corrected

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

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