Pumpkin preamp - More Boring Making Thread

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#144
Manu said:
If they are not neat and lovely, I don't know what is.

I chose wima caps because of the color :clown:
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whoa!

MKP4 - 10uF/250V ......

ya didn' found anything smaller ?

where you'll put heatsinks ?

:clown:

just in case - if you don't choose plain sheet of Al , heatsinks can be :

Fischer
SK81-50 SA
SK75-50

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

I almost forgot to say :

Ugly!

:devilr:

edit:

what's ugly greenie right from Pumpies ?

:rofl:
 
#146
Manu said:



Zeyare Caps too!
Old ones. No brand...
They are only laying there for size test purpose.

But I think I will use little wima as bypass.
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use whatever other drek you have as bypass

100n is enough

edit:

manu sez "isnogood.......?"
 

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#148
mpmarino said:
the junkyard game
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Mark,

if you take a good look you'll see at least three different resistor types on the piccy, the bulk being 2% and 5 % accurate 50ppm 0.6W Philies.(red and gold band)

Which means very little because i handpick and check each component, each R on the board is 0.1% accurate.
I've got at least 10K of the 2% red variety (forgot the exact number), bought the entire lot for $70, a few hundred of each value on a tape.
The Dales i've got at least 5K of, 1987 production series.

The smaller blue caps are 0.68uF Siemens decent quality polyester types, couldn't fit large enough polyprops there and mkp isn't exactly required at those locations.
The big blue MKP types on top are RiFa430s on the output, Siemens KP where the Rifas wouldn't fit.
On the bottom side of the board are high value 1% polystyrene caps, the very best ever made. Previously only used for RIAA purposes because they were filthy expensive.
(me used to drool at the counter of fancy shops with the little cash i had saved, nowadays i enjoy dumpster diving more than driving up to slick entrances and sometimes a dumpster contains what green bills no longer buy)

If you look hard you can come up with at least 5 reasons for the PTFE sleeving, Chinese fortune cookie proverb says Condom-Man make jokeys otherwise would be very boring arrogant prick.
You guys die if i tell about the kind of split-bobbin transformer monsters i found for the Shuntsters.

(me is pretty big but my Fata says i'm still a shorty, i told my shrink to shut up cause he doesn't exist)
 
#150
HBarske said:
Papa's toy will be gone by next week :bawling: - some diy progress is urgently needed...
Not sure if those beer cans will make it into :Pumpkin:, but I'll give them a try.
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did you found enough material for translation (for our friends at Analog ) in last :Pumpkin: Cook Book ?

:clown:


regarding previous pic:
why don't you just tell that some thieves tooked that crummy amp from ya ...... ?

and - jensens will do , but - if you have some older Siemens of Rifa uglies, don't hesitate ............ Pumpie is made with old tech in mind 😉
 
#152
Variac said:
Hey ZM,
Maybe you could mention the pages that have updates in the latest
Cookbook- you know, then we could save all those trees and not reprint he whole thing ..
😉
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yes Bwana .........

:rofl:

just one page added .......... AS LAST ONE

there it is (I mean text ) :

***********************************************
ADDITIONAL NOTES :




HEATSINKS :

Fischer
SK81-50 SA
SK75-50 OR

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


CONNECTION :


You can connect Pumpkin inputs and outputs in all combinations you can imagine ;
My advice can be – use balanced pot(s) for inputs (either one 4-deck , or two independent stereo pots) in any value you choose – from 5K to 50K , log off course .

Then use XLR chassis connectors for all inputs and outputs .

That’s certainly most convenient if you choose balanced input – balanced output configuration .

If you choose to use unbalanced either input or output (or both unbalanced) , again use XLR cable jack even for unbalanced ,and just tie ( solder) pins 1&3 inside that cable jack .

So – these combinations are possible :

- bal in : bal out
- unbal in : bal out
- unbal in : unbal out
- bal in : unbal out

In every “unbal” case – you must tie 1&3 pins in XLR ;

It’s also possible special situation – where you use bal out and unbal out in same time, but (naturally) WITHOUT tying 1&3 pins of output XLR (just because tying those pins you are just killing balanced out entirely) , where you as “unbal” out are using in fact just half of balanced signal ................... where HOT is from pin 2 (+ output) and gnd is from gnd , what else 😉 ; That’s useful for biamping purpose , where one power amp is balanced and other is not .......... and 6db difference between balanced and unbalanced is something that suits your needs .........

*************************************************


who will print entire drek , without looking what's in it?

:angel:
 
#153
Zen Mod said:

In your boots- I'll try to play safe ...... ask for another opinion, maybe I dreked something .......
hehe - "maybe" ..............
:clown:
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:hot:

edit :
Originally posted by Manu
iZMogood :
.........
And particularly the if -it-works-section is a very good place to learn .... at least for newby like me.
manu
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I have few questions about Pumpkin/shunty :
1. regarding X-former : would a "2x30V" Trafo - which gives about 80V after bridge - be a good choice or not? Or should I rob my wife to buy a new one....

2. Regarding the electrolytics in Both Pumpkin and Shunty : is there any "crucial" places where it could be worth it to use some not-so-drekky ones ?

Manu
 
#154
Manu said:

:hot:

edit :

I have few questions about Pumpkin/shunty :
1. regarding X-former : would a "2x30V" Trafo - which gives about 80V after bridge - be a good choice or not? Or should I rob my wife to buy a new one....

2. Regarding the electrolytics in Both Pumpkin and Shunty : is there any "crucial" places where it could be worth it to use some not-so-drekky ones ?

Manu
Click to expand...


1. you need +/-36V at output , after some pretty big voltage losses ;I can't recommend any voltage bellow +/- 50V on input , that's absolute minimum, and just in case that your mains voltage have no sags of -10%

2. on output of Shunty and local ones in P .
 
#160
Pumpkin Volume Control

Hi. What would be the best volume control for the pumpkin?

It is a balanced input preamp, so a few question:

If use as single ended, do we just ground one input and input the signal into the remaining input, any side is better than the other for that?

-I guest we need a balanced volume control. Is this balanced 5K serie attenuator fro K&K audio a good choice: http://www.kandkaudio.com/linestage.html

any other suggestion?

Thanks in advance.
 
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