The Sound of Two Transistors Clapping

[xrk971]

That's an Intermodulation Distortion (IMD) test and the test tones are 60Hz and 7kHz. The little blip at 130Hz is the resulting IMD product.

 

[Andersonix]

Doh! Of course! Great job!

 

[kp93300]

The sound from both amp sound great. So clean and clear. A vocal track would be nice.
Can the amp in the first post with 2 transistors ok as a preamp?
Thanks for posting

 

[Circlomanen]

Nice simple head-phone amp.

I have built a beefier version of this amp for driving loudspeakers and testing positive current output, as documented in this thread:
http://www.diyaudio.com/forums/pass-labs/301491-pcf-without-global-nfb.html

Your small mp3-clip of music sounds very clear, transparent and nice through my speakers to.


Cheers,
Johannes.

 

[xrk971]

The sound from both amp sound great. So clean and clear. A vocal track would be nice.
Can the amp in the first post with 2 transistors ok as a preamp?
Thanks for posting

Yes you can use as preamp but care is needed with clean PSU to avoid hum as there is no PSRR here. Or use large rechargeable batteries. A cap multiplier and regulator should be ok.

 

[xrk971]

Nice simple head-phone amp.

I have built a beefier version of this amp for driving loudspeakers and testing positive current output, as documented in this thread:
http://www.diyaudio.com/forums/pass-labs/301491-pcf-without-global-nfb.html

Your small mp3-clip of music sounds very clear, transparent and nice through my speakers to.


Cheers,
Johannes.

Nice power amp! Is the PCF needed? I have no feedback, and wonder what happens with PCF on my headamp.

 

[xrk971]

Here is another 2-transistor amp, this time JFET-BJT ouput. Aksa designed this one to have an adjustable harmonic profile via R4 as a "niceness" knob using a pot.

Proof of concept with 2SK170BL instead of BF862 on solderless BB works well, now off to a hand drawn PCB.

 

[xrk971]

Pocket Class A Headamp GB

I am starting a GB for the little Pocket Class A SE Headamp over in this thread:

http://www.diyaudio.com/forums/head...lass-headamp-without-heat-24.html#post4965668

PCB:

 

[xrk971]

Just a reminder if anyone here has an interest in the GB, we are at 36 boards now and it will be closing in a few days.

http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-3.html

Pocket Class A Headamp GB List

xrk971 - 2 boards
pcgab - 2 boards
zman01 - 2 boards
stellarelephant - 2 boards
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board
cyteen - 2 boards
funch - 2 boards
syyma - 2 boards
av-trouvaille - 2 boards
Mituisho - 2 boards
bogde - 2 boards
faltinsen - 2 boards
vanofmonks - 1 board
M_Balou - 2 boards
dwpeterson - 1 board
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards

 

[kp93300]

Zvn 4306 overheating

I built the circuit according to the schematic in the first poat. Manage to trim the voltage at source of zvn at 6.5v. Very nice sound but zvn is too hot to touch a few minutes after power up.
input voltage is 16 v .
ZV bought from element14
Any pointers to solve the problem?

 

[juma]

... zvn is too hot to touch...

Sure it is.
It is dissipating about 0.5W ((6.5/120)*9.5) so some sort of heatsink is needed.
You are using TO92 part and it makes heatsinking a bit more problematic. If you were using an SMD part that would allow for easier heatsinking (by using the large copper area on the PCB).

 

[xrk971]

I built the circuit according to the schematic in the first poat. Manage to trim the voltage at source of zvn at 6.5v. Very nice sound but zvn is too hot to touch a few minutes after power up.
input voltage is 16 v .
ZV bought from element14
Any pointers to solve the problem?

Nice work. Thanks for trying it.

Use a TO-92 heatsink or use SOT-223 and large copper plane for heatsink.

SOT-223 actually easier to solder than TO-92.

 

[xrk971]

Here is another 2-transistor amp, this time JFET-BJT ouput. Aksa designed this one to have an adjustable harmonic profile via R4 as a "niceness" knob using a pot.

Proof of concept with 2SK170BL instead of BF862 on solderless BB works well, now off to a hand drawn PCB.

PCB with built in cap Mx and powered with a DC-DC converter to get 20v rail from 5v to 24v input:

 

[kp93300]

Hi X,
I have 2sk170 and bd140. Can you post the schematic ?
Thanks

 

[xrk971]

Hi X,
I have 2sk170 and bd140. Can you post the schematic ?
Thanks

Here's the schematic - thanks to Aksa for the simulation and design!

More info in this thread:

http://www.diyaudio.com/forums/solid-state/301164-mosfet-source-follower-headamp-30.html

 

[kp93300]

2sk170 replacement

Is 2sk170 a drop in replacement for the BF? No other changes to the circuit you posted?

 

[xrk971]

Yes, I dropped in a 2SK170BL and it worked - the Idss of the 2SK170BL should work nicely with a 7mA requirement. If you get a chance, buy a roll of BF862's they are very inexpensive and nice devices to work with. About $0.40ea from Mouser/Digikey and half that from eBay/China - don't worry, no one is bothering to fake a 40cent SOT23 (yet).

 

[kp93300]

Improvised heatsink for zvn. Zvn reaches about 60 deg C after a while and stays there.
No hum.
Thanks to juma and xrk

 

[xrk971]

Good that you got it cool down.

I see two heatsinks. Is that other one for sk170?

 

[xrk971]

Effect of niceness knob (degeneration resistor) on JFET-BJT headamp.

http://www.diyaudio.com/forums/solid-state/301164-mosfet-source-follower-headamp-33.html#post4971963