Pumpkin preamp - ordered by Steen , official making thread

[lykkedk]

Hi ...

ZenMod, when you tell to place voltmeter, at outerpin of C4 / C5, you mean at the point, where R13 meets C4(-out) , and where R18 meets C5 (+out) right ? - seem's a little hard to understand 100% (at least for me ). Well my pumpkin have been playing for several week now., but i will recheck the adjustment's when i somehow in future get chance to put it in box

C4 / C5 is the 10uF outputcap's you're meaning in the assembly-instruction's right ???

Jesper.

[Zen Mod]

Originally posted by lykkedk
Hi ...

ZenMod, when you tell to place voltmeter, at outerpin of C4 / C5, you mean at the point, where R13 meets C4(-out) , and where R18 meets C5 (+out) right ? - seem's a little hard to understand 100% (at least for me ). Well my pumpkin have been playing for several week now., but i will recheck the adjustment's when i somehow in future get chance to put it in box

C4 / C5 is the 10uF outputcap's you're meaning in the assembly-instruction's right ???

Jesper.

let me see ........

C4 and C5 from Pumpkin schematics ;
outer pins - physically outer on pcb , far left and far right side ......

I'm clearer now?

[lykkedk]

C4 and C5 from Pumpkin schematics ;
outer pins - physically outer on pcb , far left and far right side ......

Yes Yes I know, i thought it over today, and see what you mean, regarding the placement of the output cap's...

I have attached a schematic, with 3 grey spots on, pointing on the meassuring point's, are they located the right places on schm. ???

Jesper.

[Zen Mod]

Originally posted by lykkedk


Yes Yes I know, i thought it over today, and see what you mean, regarding the placement of the output cap's...

I have attached a schematic, with 3 grey spots on, pointing on the meassuring point's, are they located the right places on schm. ???

Jesper.

grey spots are on spot

[lykkedk]

Good ZenMod.... Then things will work for dummies (ahh like me ???) too !!!

Btw... I use a 10k stereo alps pot on input, you somewhere in the past mentioned something about what's fit your'e source best... Well i donno what impedance my DDDAC / PearlPhono have, so do you have any good suggestion, for an allround pot... meaning values both for stereo + eventually an balanced one. Maybee this could interest someone else too ... Anyway, keep up good work ...

Damn... i haven't got much time listning to dreky... and finishing up thing's - Right now i am designing an inputselector, with 3 unbal RCA input's + 1 balanced input + balanced/unbalanced switch for output, for futureproof - all along with a switch, where you can switch between two toslink input's... All that must go into dreky too.

I was inspired to make this myself, looking at twistedpears darwin-input-selector btw:.. But this is way O.T. sry for that.

Jesper.

[Zen Mod]

WiFi in strike .........
sending this from dialup ............

Lykkkkkkkkkkk .... later tonight....

[Zen Mod]

Originally posted by lykkedk
Good ZenMod.... Then things will work for dummies (ahh like me ???) too !!!

Btw... I use a 10k stereo alps pot on input, you somewhere in the past mentioned something about what's fit your'e source best... Well i donno what impedance my DDDAC / PearlPhono have, so do you have any good suggestion, for an allround pot... meaning values both for stereo + eventually an balanced one. Maybee this could interest someone else too ... Anyway, keep up good work ...

well - did you saw AR2's solution - two Black Widows (AKA Blue Velvets ) , each stereo 50K pot ?
one per channel, so you have in same time balance too ....
that variant is both marked as good and also as bad , depending which personal preference is in question.....
anyway - 4 channel ALPS aren't so expensive - I think somewhere in range of 40 Euro ............... look HERE ..... that's my friend from Geek toob forum ......

I presume that you don't want Magura San to make eeeny weeeny attenuator for you , except if you have spare room just for them

in any case - it's better to use as low attenuator value as you can, considering output impedances of your sources ; if sources are happy with 10K pot - then use 10K pot ; anyway Pumpkin is made with input impedance in that range ( remember value of resistors in both J310's gates )

Damn... i haven't got much time listning to dreky... and finishing up thing's - Right now i am designing an inputselector, with 3 unbal RCA input's + 1 balanced input + balanced/unbalanced switch for output, for futureproof - all along with a switch, where you can switch between two toslink input's... All that must go into dreky too.

I was inspired to make this myself, looking at twistedpears darwin-input-selector btw:.. But this is way O.T. sry for that.

Jesper.

my advice , and you know that I'm always willing for at least one is - use 4 channel volume pot , use only XLR connectors on input and also on output , use mini relays for input selector ( one double Takamisawa per channel input , so - when rely is not in use , both signal rails are grounded .

then - if you need to use nonbalanced source, just short gnd and minus leg ditto in cable XLR of that source

clear enough ?
I'm not sure ........ sometimes is hard to force my Engrish to follow what I want

[mpmarino]

clear enough ?

yeah, I think so... Your Engrish is better than you think

Ya know... I've been toying with the idea of building a separate input select/attenuator module with remote volume. Sort of what someone might build as a passive 'pre amp'( I always wondered how you could have a passive preamp?) Fully balanced input to output using whatever good components I have in the drawer. This would simply go between the sources and the pre. The actual pre would just be a box with 1 in and 1 out. Nice n' easy.


Why? you ask?
Maybe you didn't ask why- but I'll tell you anyway. Whenever I build a preamp circuit I'm finding that the most difficult part is the in selector and the attenuator - partswise. Also, it's hard to compare circuits because I never end up with the same type of attenuator. In doing this I would never have to scrape for an attenuator or input selector again - just keep using the same one.

Whadya think?

[Zen Mod]

Originally posted by mpmarino


..................
Ya know... I've been toying with the idea of building a separate input select/attenuator module with remote volume..................

Whadya think?

"....cunning plan......"



( Babelfish 2SJ74 are matched and packed ; post office tomorrow ....today........ now is 05:27 local time )

[lykkedk]

clear enough ?

Yep... allmost

in any case - it's better to use as low attenuator value as you can, considering output impedances of your sources ; if sources are happy with 10K pot - then use 10K pot ; anyway Pumpkin is made with input impedance in that range ( remember value of resistors in both J310's gates )

Are you telling me, that 5k is better suit's than a 10k one, if i got the choice ?

when rely is not in use , both signal rails are grounded .

Just soo, that any unused 'source' are grounded, when not in use ?

NICE answers ZenMod...

Jesper.