Babbelfish J PCBs

[Zen Mod]

ook , Jaccolina

less Dutchie , more Serbian , please

so , entire World can understand ya

 

[brianco]

It's apparent that Pao is backwards, and really doesn't like p-channel power devices. (especially the hump-backs)

Hey....that's me you mean!! Poa, backwards that is. It means Old Age Pensioner......you cheeky young dutchie whippersnapper.
AND, although I am not as straight statured as I was , but am NOT (yet) a hunchback!

 

[dieringe]

well - something like this

I built this headphone thing - with 2SK389 and reversed polarity, and reduced R13 to 22k for 300 mA.
Problem: it is humming which gets worse when I plug in any input, balanced or unbalanced. Any idea?
Sound is great as far as one can tell with a background hum ...

 

[Zen Mod]

have you any graphical info , you can post here ?

 

[dieringe]

You mean images?

(The pot is not connected)

What would you think is the minimum supply capacitance? Maybe these caps are old...
Supply ripple is 0.5 V

 

[Zen Mod]

ripple of 0V5

you're building a buzzer , or amp ?

 

[dieringe]

You say I need around 2 x 20000 µF or what

 

[Zen Mod]

more the merrier

CRC of 10mF-0R1-10mF per rail , will do the job for stereo

 

[dieringe]

CRC of 10mF-0R1-10mF per rail , will do the job for stereo

Ok done this and the hum is nearly gone, practically it is ok.

Any suggestion how to connect a volume pot? I tried one shorting the + and - inputs but makes it really hum ...

gate - 1k - pot pin - 22k - input+
            0..100k
gate - 1k - pot pin - 22k - input-

 

[Zen Mod]

what source you're using - SE or balanced ?

 

[dieringe]

balanced

 

[dieringe]

If I turn the pot down the output DC rises
Unmatched output FETs?

 

[Zen Mod]

click on this: PSM LS Cook Book , in my signature , then you'll know more about attenuator wiring

 

[Zen Mod]

If I turn the pot down the output DC rises
Unmatched output FETs?

two things for setting Iq and output offset :

- ground inputs
-no load on output

if attenuator is connected properly , no change in output offset

 

[dieringe]

I wanted to avoid a quadruple pot, and electronics ...
I moved the pot to before the 22k and added 16k before that. Working well, no hum. Change of offset is a few mV now.
Sound is so far very nice, probably can be tweaked ...
Thanks

 

[Le Thien Thanh]

I do not have VR 47Ohm. So I can replace. and adjusting VR1 and VR2 ???.
Sorry for bad english .

 

[Le Thien Thanh]

I do not have VR 47Ohm. So I can replace. and adjusting VR1 and VR2 ???.
Sorry for bad english
Thank You !!!! .

 

[Zen Mod]

I'm in Mountain , with wimpy net connection

I'll be back in a week or so ......... then will reply , if nobody chime in

however , according to

use 50R as 47R and 50K as 47K ;matter of local availability

 

[Michael Mik]

I just start the artwork for the pcb on the Babelfish J with input SJ109BL (because I have some).
I also have a lot of 0.47 Ohm/5W resistors. Would there be an easy way to calculate the needed R- value with a given voltage and Iq and so the output wattage or other way around?
Or in other words: I like to use these resitors and my max. power should be 25-30 W, so which voltage and Iq I have choose?

 

[Dennis Hui]

I guess you can use the design as-is and just use a parallel pair of 0.47 ohm resistors
where you see 0.22 ohm ones. The differences should not be large.