DIY Power supply for a Szekeres headphone amp

[Tomo]

Hello,

IRF510 works fine for me. But I was told by fa-schmidt at HeadWize that Toshiba counterpart of IRF513 (Thus low power MOSFET. IRF510 is pretty high power ... medium scale.)

I was a little skeptical at first, but after fa-schmidt giving me a completely review, I feel it might be worth a shot. Besides these cost like couple dollars unlike 300B.

Don't get all caught up in DC coupled design. Recently there are reports that if DC coupled version give off pretty powerful DC offset at turn on and off that persist for over few secs. Unless the output has DC offset correction, I am no longer confident as to its safty. (AC design isn't all that bad, I enjoyed for quite a while before upgrading my system.)

You should use good PSU, but I don't think using massive amount (over 10,000uF) is a good idea. You should feel some fear simply by thinking about that much capacitance. It almost always means trouble if not careful.

With 10,000uF, your amp should operate WITHOUT power for nearly 1 min. I say that is enough. Use sophisticated paralleling of somewhat small ceramic and several other caps for optimum effect. That is more important that maxing out caps. (I think you all agree to that if you are building a headphone amp.)

Tomo

[Jean]

I am using IRF511s and they seem to work just fine, and aren't hard to find. Got mine from Mouser or Digikey.

Question , how exactly does one calculate how big of a heatsink I would need for LM317 with 25 volts going IN and 15 out ?

Thanks!

[halojoy]

I agree with you Tomo.

Headphones are very easy to burn,
compared to Loudspeakers.
So you have to be careful not using a construction
that is putting out DC-offset too long.

I would like to recommend AUDIO OSCON (solid electrolyt).
They are much better, and will have longer life, than any wet electrolyte
like them Black Gate or what they all are called.

Put several in parallell, if you have low impedance Headphones,
and you want a low cutoff frequency.

If you are a very rich man, use Parallelled Polypropylene.
That is the ultimate way.

I say, you will not lose anything in sound
if you use that solution at output.

[MWP]

Originally posted by Jean

Question , how exactly does one calculate how big of a heatsink I would need for LM317 with 25 volts going IN and 15 out ?

25 - 15 = 10V drop across LM317
At a current draw of say 1A, gives around 10W of heat dissipation from the LM317.

My split rail double layer PCB (LM317 & LM337 regulation):

[traderbam]

Well, the "BAM headphone buffer" would have split rails and, unlike the direct-coupled design G posted, it would use an output cap between FET and headphones and thus eliminate all of the input parts aside from the potentiometer. It would use a CCS to load the FET.

The sound would be better still if a pair of bipolars were used instead, say in CFB configuration. Bipolars are considerably more linear in this application.

[Bricolo]

have you got z design for a bipolar transistor based amp?
one that wouldn't be much more complicated than the Szekeres?


My transformer is a 230V 12V 60VA toroid one
only 2 output wires

does DC provide a better sound?

[trwh]

"have you got z design for a bipolar transistor based amp?
one that wouldn't be much more complicated than the Szekeres?"

http://sound.westhost.com/project70.htm

See ya,
Tim.

[traderbam]

Here's a bipolar design. I've just acquired this schematic capture software so I'm not too good with it yet.

Most part values are the same as in your original circuit. Voltages are +/- 10V to 15V as before. The Current source is 500mA. Driver transistor pnp ZTX753 or similar, output npn MJE243 or similar. base to gnd resistor at pnp is 22k. You need psu caps from both rails to ground too (not shown).

That's it. It'll sound sweet as a nut.
BAM

[Bricolo]

has someone already built this one?

[Bricolo]

Originally posted by Tomo
Hello,

IRF510 works fine for me. But I was told by fa-schmidt at HeadWize that Toshiba counterpart of IRF513 (Thus low power MOSFET. IRF510 is pretty high power ... medium scale.)

I was a little skeptical at first, but after fa-schmidt giving me a completely review, I feel it might be worth a shot. Besides these cost like couple dollars unlike 300B.
Tomo

Can you tell me more about this toshiba mosfet fa-schmidt told you?