New PassDIY Headphone Amp (now available)

[JPS64]

Mouser 14.08.2017; Farnell ?; Kunisch next week; Don-Audio next week.

Here the beast I´m using for the test.

JP

 

[wayne]

Dear Wayne,
What do you think, it can be used in balanced or bridged mode?
I mean one board for left channel and one for right channel.
If it can be possible, then I send you the money right now for another PCB.
Thank you in advance,
Gyuri

I don't see any reason you couldn't do this just feed each board a balanced signal.

 

[Gyuri]

Thanks, Wayne,
I suspected it will works, but it is nice to hear from its designer.
So there isn't any obstacles against it, other than that I need a second PCB.
Can you send me a new invoice, or I just simple send 55$ to you Pay-Pal account?
Regards,
Gyuri

 

[JPS64]

Could someone measure the primary and secondary DC resistance of the TALEMA PCB toroid transformer?

I´ve about 6 ohm for one secondary?

JP

 

[JPS64]

Saturday soldering.

JP

 

[kevinr]

do you install insulating washers between the jfets/voltage regulators and the heat sinks ?

 

[JPS64]

Regulators are FP type.

Mosfet becomes a condom, ordered for 2 hours.

Have big problems with inrush current: Toroidal death or filter cmc + toroidal blows 2A slow bow fuse!

JP

 

[wayne]

2 amp slow blow should work fine. I measured my secondaries at 4-6 Ohms depending on transformer VA.

 

[JPS64]

230 Ohm primary and 6 Ohms secondary with 230V and 15VA.
2A blows! Will check without main filter...

JP

 

[EUVL]

I have 2x 25VA Talema and 0.5A slow blow for my F5-HA.
Never have had a problem.

So something else wrong.


Patrick

 

[JPS64]

Hello Patrick,

do you use in your F5-HA main filter with CMC?

My Schurter main filter includes an 2x4mH CMC; main filter checked ok (removing middle point connexion of toroidal 230v side) with 2A SB fuse.

As always, I think something really stupid is going on (perhaps wrong fuse? Ordered new ones).

JP

 

[Gyuri]

I have two questions:

Are there any penalties (soundwise) if I would be used Fairchild FQP3N30/FQP3P20 pairs instead of Toshiba 2SK2013/2SJ313 pairs?

Need I change to something in the schematic?

Regards:
Gyuri

 

[alvinlim]

I have two questions:

Are there any penalties (soundwise) if I would be used Fairchild FQP3N30/FQP3P20 pairs instead of Toshiba 2SK2013/2SJ313 pairs?

Need I change to something in the schematic?

Regards:
Gyuri

Should be fine - no change to the schematics. No idea about the sound though.

 

[wayne]

The Fairchild parts work just fine. Sound is very close between the two I can't tell the difference maybe some can.

 

[Gyuri]

Thanks guys,
I asked because I have two pairs of 2SK2013/2SJ313 for one PCB, and virtually countless pairs of FQP3N30/FQP3P20.
Then I will order missing parts for two boards.
(Wayne, have you got the money for second board?)
Another thought, can I raise power supply voltages?
Because if I can understand it well, with Fairchild pairs output voltage swing will be lower. Not if it count if I only drive headphones with it, perhaps I would drive my balanced F4 with it.
Any suggestion in this regard?

 

[EUVL]

Rail voltages higher than +/-18V will severely limit your choice of opamps, not ?


Patrick

 

[Gyuri]

Thanks Patrick,
Of course I know that there are limits for opamps PS voltages, despite I'm Wacky One. Although OPA2604 doc says to me max.+-24V operating voltage range.

 

[EUVL]

> will severely limit your choice of opamp ....

So other than OPA2604, which other ones can you choose ?

Unless of course you already decided to use OPA2604, then by all means.
The MOSFET will take it with easy.


Patrick

 

[Gyuri]

You know Patrick, I haven't decided anything yet, except that it will be in balanced configuration.

 

[Variac]

Wayne's 'phone amp will be discussed and demo'ed by Wayne at Burning Amp 2017:

Here: