Pumpkin preamp - ordered by Steen , official making thread

[Zen Mod]

Originally posted by mpmarino


Bingo! 37 is right in the middle


.......

so - you are nothing else than , poking from hole here and there

[carpenter]

The question is: Does the fly operate in class A? The rod is after all a push/pull device...

[dviswa]

Originally posted by Zen Mod

you package ( + ) , along with others is packed and ready to sending ;

Thanks a lot.

Originally posted by Zen Mod
seems to me that you found your fave caps just go for it .

Thanks, I will.

Originally posted by Zen Mod
somewhere - in one of my useless OT threads - I mention that I tried with cans - with stock (4uF) output caps , cans's impedance was ...... both channels in parallel - so must be no more than 50 ohms........

to cut a ... sound was pretty decent , no flabbyness ....... blabla

think about decreasing output resistors to ~ 22E , from 47 as they are now ;

OK, anything else I should be changing?

Originally posted by Zen Mod
if needed - we can later try something simple - increasing Iq in output stage(s)

don't forget to take cans off the head , if BG's need little burning in

I was wondering about it too. Let's say I want to double the Iq, what values should I be considering?

[Zen Mod]

Originally posted by dviswa

............

Let's say I want to double the Iq, what values should I be considering?

roughly speaking .........


halving all mosfet source resistors ;

so - R11 & R16 to 15~18E , R12/R26 & R17/R28 to 330//240E (all that in Pumpkin)


so - that also need changes in Shunty - besides xformer capable to give ~ 82Vct/800mA minimum for stereo , all heatsinks twice thermally capable ( that applicable for Pumpkin too ) and decreasing R7/R7a to 2E4 (Shunty)


in that case you'll double present current hunger of Pumpkin/Shunty combo , which is ~140mA/channel

so - you'll have preamp drawing 82V x 0,28A x 2 =46VA ......

more than some hifi DrekMKXX SE^2 amps

[lykkedk]

anyway - it's up to you to choose what's best for your ears

This is not a problem... no difference between soundsonics of 10xgain and 20xgain

Actually, i am not having trouble, with the gain anymore, it was just an idea i have, that maybee someone else was gainhungry like me too ! ... I allready adjusted the gain to my need's... I see ofcause that the phono-pre, can't be playing as loud as i would like it to, with a gain of 20x, but it's good enough for now.

I realise, that this is not the right place to ask, about howto calculate such thing's as X-feedback OLG, CLG... etc... seem's that anyone else but me, understand's this.

I am going to study these technicue's in future... regarding gain/loop etc... that i don't understand quite well... And maybee (can't promise) i will try the meassuring ZenMod suggested.

Anyway, in next few day's.... sneakpreview of my inputselector

Greeadylykkedk.... yes i am

Jesper.

[jormajj]

The Pumpkin and Shunty PCBs arrived today, Thanks Choky and OLy !

Great looking boards

Here are some examples of heatsink types fitting on the PCBs
( 50 mm high):

Fischer
SK81-50 SA
SK75-50

Austerlitz
KS100.3-50
KS32.1-50E

jormajj

[Zen Mod]

Originally posted by jormajj
The Pumpkin and Shunty PCBs arrived today, Thanks Choky and OLy !

Great looking boards

Here are some examples of heatsink types fitting on the PCBs
( 50 mm high):

Fischer
SK81-50 SA
SK75-50

Austerlitz
KS100.3-50
KS32.1-50E

jormajj

tnx jormajj

[vitalstates]

I wonder...did steen ever get caught with his flies undone???

the real question, choky OLD chap....my F4 sings with my squeezebox and I can only get the volume up half way....this means that thinking about pumpkin is idling away the time for no good reason???

Ed

[Zen Mod]

Originally posted by vitalstates
I wonder...did steen ever get caught with his flies undone???

the real question, choky OLD chap....my F4 sings with my squeezebox and I can only get the volume up half way....this means that thinking about pumpkin is idling away the time for no good reason???

Ed

well........ you have schematics , cookbook, few hysteric threads for easy reading for fun ....... what are you waiting?

[jacco vermeulen]

Q is to Pump or not to Pump ?

(don't know about you lot, but Steener better not show me any undone flies)