Selecting parts for Pumpkin build
While I await the arrival of my Pumkin / Shunty boards, I am accumulating the parts for my build. I am really excited about this build. I'm neck deep into a pair of Aleph-X monoblocks (And a Dumble clone guitar amp...but that is another beast altogether). I think the Pumpkin will be just the ticket to drive the monoblocks. Any thoughts on the following:
I have a 100VCT 530VA toroid that is looking for a home. It is overkill, but I don't have another use for it.
I have Auricaps for the outputs (and inputs, if needed). For the Electrolytics, I'm going with Elna Silmics. The other film caps are Wima. Anyone have potentially better sounding alternatives?
For resistors, I am looking at PRPs to supplement the few Riken Ohms that I have around. Any thoughts on the PRPs?
Thanks in advance for any input/suggestions.
Paul
While I await the arrival of my Pumkin / Shunty boards, I am accumulating the parts for my build. I am really excited about this build. I'm neck deep into a pair of Aleph-X monoblocks (And a Dumble clone guitar amp...but that is another beast altogether). I think the Pumpkin will be just the ticket to drive the monoblocks. Any thoughts on the following:
I have a 100VCT 530VA toroid that is looking for a home. It is overkill, but I don't have another use for it.
I have Auricaps for the outputs (and inputs, if needed). For the Electrolytics, I'm going with Elna Silmics. The other film caps are Wima. Anyone have potentially better sounding alternatives?
For resistors, I am looking at PRPs to supplement the few Riken Ohms that I have around. Any thoughts on the PRPs?
Thanks in advance for any input/suggestions.
Paul
I'm no expert here, but ... I'd be a bit worried about a large donut near the 
If you have to make use of it, I'd track down some mu-metal banding of sorts and make sure to orient the exit location of the wires away from everything else.
If you have to make use of it, I'd track down some mu-metal banding of sorts and make sure to orient the exit location of the wires away from everything else.Re: Selecting parts for Pumpkin build
I'm using mostly PRP's, Panasonic FC electrolytics, and Wima films. I have a big set of 4.7uf Wima MKS10's to try as coupling caps, bypassed by something nice.
That transformer sounds a little high on voltage and I agree it may be big for inside the case. If I were using it I'd probably put it in a separate box somewhere. I am using a couple of Antek AN0540's which are 50VA 40-0-40's, locating them in another box via a 7 pin connector to the preamp case.
Good luck with the build!
Tom
We're going to be on parallel paths here as I'm also assembling parts while I wait for the boards.pdrie said:
I'm using mostly PRP's, Panasonic FC electrolytics, and Wima films. I have a big set of 4.7uf Wima MKS10's to try as coupling caps, bypassed by something nice.
That transformer sounds a little high on voltage and I agree it may be big for inside the case. If I were using it I'd probably put it in a separate box somewhere. I am using a couple of Antek AN0540's which are 50VA 40-0-40's, locating them in another box via a 7 pin connector to the preamp case.
Good luck with the build!
Tom
Shunty's are alive
ZM sent me the full package with all the goodies, so the Shunty's went together without problems. Here is a view of them running with dual Antek 40-0-40 toroids, which will be in an external case with umbilical. Temporary heatsinks seem to work fine and the supplies are very stable once they start cooking.
Thanks again Zen Mod, so far so good!
Tom
ZM sent me the full package with all the goodies, so the Shunty's went together without problems. Here is a view of them running with dual Antek 40-0-40 toroids, which will be in an external case with umbilical. Temporary heatsinks seem to work fine and the supplies are very stable once they start cooking.
Thanks again Zen Mod, so far so good!
Tom
Attachments
my heatsinks on the shunty get very hot. I hope that aluminum sheet works out for you... plan for lots of ventilation!
Those are just temporary sinks and yes, they are rather toasty 
Fortunately, I have some of the Fischers on the way to replace those when they finally go in the case.
Fortunately, I have some of the Fischers on the way to replace those when they finally go in the case.
I got my hand slapped many a time for nicking those very same meters out of my father's tool bag and playing with the continuity check function 🙂
I just bought the pair of those 8060a's for about $50 each in like new condition from a surplus house that got several in from a liquidation. Might have been new in boxes never used, so I jumped on them. It is great for audio use, with dB, Relative, high bandwidth True RMS, and even Freq measurements, at least within the 3 1/2 digits of A/D count (not auto ranged).
Adjusting the offsets on the Pumpie is making me
even though it's in a case cooking to steady temp, with no breezes. I fear a servo or tiny cans on the jfets may be the only way... Seems to play music just fine, but I worry.
Adjusting the offsets on the Pumpie is making me
even though it's in a case cooking to steady temp, with no breezes. I fear a servo or tiny cans on the jfets may be the only way... Seems to play music just fine, but I worry.
tms0425 said:
do not worry 😉
small daughterboard , with nice servo is planned , as freebie for all pumpie builders ;
I think in few months I'll have them finished .
have you some more - less cryptic , impression of pumpie sound ?
That sounds great!Zen Mod said:
I am only using it as a fixed gain stage (after the DCX2496) on the bass/lower midrange section of my Emerald Physics speakers (up to 1200 Hz) with mono F4's, and an F5 on the HF compression driver/waveguide from 1200 Hz up. So far as a total package, with a little bit of complexity, it sounds very good. Only a few hours listening so far though. Maybe this weekend I'll get a little more time. Unfortunately, I really need a balanced attenuator to try it full range before making any meaningful conclusions.
Shunty positive voltage wrong
I had tested my shunty boards before I mounted them in a case and they were fine. I have since mounted them in a case and my positive voltage is +40V and it will not adjust. I have checked the obvious shorts cold solder joints to no avail . Any ideas were to start?
Bill
I had tested my shunty boards before I mounted them in a case and they were fine. I have since mounted them in a case and my positive voltage is +40V and it will not adjust. I have checked the obvious shorts cold solder joints to no avail . Any ideas were to start?
Bill
Re: Shunty positive voltage wrong
any picture ?
what is major physical difference between test and actual position in case ?
possible short with metal spacers , or overtightened screw ?
irrelevant ; without load and with load - output voltage difference is minimal ;
😉 without load , Shunty is just hotter ......
wirewiggler said:
any picture ?
what is major physical difference between test and actual position in case ?
possible short with metal spacers , or overtightened screw ?
tms0425 said:
irrelevant ; without load and with load - output voltage difference is minimal ;
😉 without load , Shunty is just hotter ......
luvdunhill said:
it's of multi-double variety .......... just because is still in my head ......
I hope - not for long .....
😉
Zen Mod said:
it's of multi-double variety .......... just because is still in my head ......
I hope - not for long .....
😉
x 2If you'd like to play with some TI OPA445, I might be able to help you out on that. Seems a little out of character though, such a expensive part..
luvdunhill said:
If you'd like to play with some TI OPA445, I might be able to help you out on that. Seems a little out of character though, such a expensive part..
that will be completely contrary to entire idea of Poor Serbian Man preamp (ok ..... Papalike , I know that you insist 😉 ) ...... with cheap 'n' easy to find parts .......
who need faster and better than plain ole LF3xx variety OP for servo ?
problem was that I wasn't satisfied with few servo variants I tried during Pumpie breadboarding .......
now I have cunnin' plan ..........
