The 
10 years and still going strong. ZM must have done well with napkins and pencil 😎 Those boards have coolness factor....
10 years and still going strong. ZM must have done well with napkins and pencil 😎 Those boards have coolness factor....An externally hosted image should be here but it was not working when we last tested it.
Thank you very much. I've been missing you too🙂
I made a few mods on my Pumpkin, and reading through the Pumpkin manual, it dawned on me that 10 years had passed..... Chocking. BTW the child drawing puts a smile on my face, every time! Anyway, going through my stash, i found a few 2sk369V's, that needed a good home, so good old Pumpkin was in for a little surgery. I also made a few more mods, like the inputcap subboard, with provision to short -IN to GND via a jumper and some other small tweaks...
I made a few mods on my Pumpkin, and reading through the Pumpkin manual, it dawned on me that 10 years had passed..... Chocking. BTW the child drawing puts a smile on my face, every time! Anyway, going through my stash, i found a few 2sk369V's, that needed a good home, so good old Pumpkin was in for a little surgery. I also made a few more mods, like the inputcap subboard, with provision to short -IN to GND via a jumper and some other small tweaks...
An externally hosted image should be here but it was not working when we last tested it.
damn ..... that big pcb , with selector and everything onboard (maybe just mono ) and with servo to avoid all caps ........ it's always on back burner .....
🙂
🙂
Pumpkin V2.0, count me in 🙂 Not sure about the servo, though. Input caps might be a better solution, if good caps are used (just some polyprops) Pumpkin has an extremely good definition and soundstage as is. Topology and Shunty, are probably main reasons for this.
One more pic:
Pumpkin has to be taken out, and put on top shelf for extended listening periods. You might want to take a look at the dissipation, for environmental reasons
🙂An externally hosted image should be here but it was not working when we last tested it.
The builds I have seen all use the volume (pot or discrete) before the input. Would it be an advantage to use an Aleph P1.7 style attenuator at the output? If so, what values would be suitable?
yeah
damn
planning that thingie with servos , no caps in signal , and all whistles ........ two biggie mono pcbs with selector , shunt regs and gain part together ....... but being regularly distracted Babelfishing all these Sissy amps , Papa tossing out every 2.5 hrs .....
damn
planning that thingie with servos , no caps in signal , and all whistles ........ two biggie mono pcbs with selector , shunt regs and gain part together ....... but being regularly distracted Babelfishing all these Sissy amps , Papa tossing out every 2.5 hrs .....
Hi Zen Mod,
I have been thinking of making a universal attenuator board to be controlled by an arduino. I like the ap1.7 design and would like to use it for other amps, like the pumpkin.
Can I use an ap1.7 type attenuator (schematic from ap1.7 service manual), replace the attenuation resistors with 50k, 100k, 200k, 400k, 800k, 1M6 and 3M2 (I think this would give a 25k input impedance) and place before input of the pumpkin? Or is a different type of attenuator better?
Thanks,
Albert
I have been thinking of making a universal attenuator board to be controlled by an arduino. I like the ap1.7 design and would like to use it for other amps, like the pumpkin.
Can I use an ap1.7 type attenuator (schematic from ap1.7 service manual), replace the attenuation resistors with 50k, 100k, 200k, 400k, 800k, 1M6 and 3M2 (I think this would give a 25k input impedance) and place before input of the pumpkin? Or is a different type of attenuator better?
Thanks,
Albert
be my guest 🙂
remember , as long attenuator is preceding preamp's input, value of att. is matter of source Rout , preamp being totally irrelevant in that
remember , as long attenuator is preceding preamp's input, value of att. is matter of source Rout , preamp being totally irrelevant in that
1. yes - one Shunty for two Pumpies , with better heatsinking than for 2+2
4E7 is old European trick to confuse boyz from other side of Big Splash
Hi,
I am prepping a parts order (the boards have now reached suffienct age) 😀
I am thrown by the 4E7 notation as well. Can someone confirm my understanding below:
4E7 = 4.7 Ohms
390E = 390 Ohms
Thanks!
yup
yup
E being sorta European designation for Ohm, in context
why's that odd for you guys on the other side of Big Splash, don't ask me
🙂
yup
E being sorta European designation for Ohm, in context
why's that odd for you guys on the other side of Big Splash, don't ask me
🙂
E for Ohm.
Probably because it's a measure of Electrical resistance, not to be confused with Electrical current.
Probably because it's a measure of Electrical resistance, not to be confused with Electrical current.
It now has an especially fond place in my heart since calculators commonly use E for exponential notation. Hey, while we are at it can we please start using i for imaginary numbers like our math brethren? i is the perfect letter for Xc=1/iwc. It just looks nicer without the dangling j.