Beautiful
I am super excited
Bubba Uncle Bob, I presume?
You're about to be very, very happy.
My experience with high end stereo components is not extensive, but the Iron Pumpkin must be one of the best sounding/functioning preamps on the planet.
Hi ZM,
Please help me understand a couple of things regarding your Pumpkin SE as in post #2 JFET cell diagram:
Why have you chosen to include R32 100r and why the R34 1r for the - side supply while 0r R38 for the + supply side?
In what situation is the "loading optional" resistor used?
Thanks. nash
Please help me understand a couple of things regarding your Pumpkin SE as in post #2 JFET cell diagram:
Why have you chosen to include R32 100r and why the R34 1r for the - side supply while 0r R38 for the + supply side?
In what situation is the "loading optional" resistor used?
Thanks. nash
R32 - it could be 0R (no resistor) , but better to have some resistance at gate, acting as gate stopper
R38 is a part of so called WCF option, which I later excluded from pcbs; White Cathode Follower, rearranged to JFet world by E. Borbely
R24 - 1R - that's position where I'm monitoring Iq, to set it at 20mA ....... 20mA through 1R is 20mV
Understood about R38 and R34. R32 100r is in the Gate to Source connection in the CCS which already has the 39r//trimmer in the loop ; thats why I asked the question.
Since I want to use my Slagle AVC which is boxed with RCA ins and outs, can I connect the AVC out+ and - points on the Iron Pumpkin PCB to RCA connectors on its case and then connect a short cable from there to my AVC unit?
I am probably missing reading this but for the SE PCB's do I need two transformers with 15ACV secondaries?
Thanks again. nash
yes, you can use "outbox" placed AVC
all Iron Pumpkin pcbs (be it SE or Bal) are made as strictly separate channel, including dedicated shunt reg
so, either separate secondaries for each channel (xformer common for both channels), or separate xformers - one per channel
external supply 30 VDC?
As I am planning to build a Pearl II Phono stage alongside the Iron Pumpkin and the supply voltages are the same, I thought it might be a good idea to feed both from one external supply with 30 VDC.
I´d use only one big x-former (2x22V) rated at 300VA and 80 mF total capacitance on the universal PSU board from the shop with 10 Ohms CRC filtering.
Bad Idea or should I even go dual mono on the supply as intended?
Many thanks
Ozo
As I am planning to build a Pearl II Phono stage alongside the Iron Pumpkin and the supply voltages are the same, I thought it might be a good idea to feed both from one external supply with 30 VDC.
I´d use only one big x-former (2x22V) rated at 300VA and 80 mF total capacitance on the universal PSU board from the shop with 10 Ohms CRC filtering.
Bad Idea or should I even go dual mono on the supply as intended?
Many thanks
Ozo
1. Good Gemini regs are made in that way so they don't care are you having 10VA Donut or 1KVA Donut feeding each channel, but Iron Turtle would complain if Donuts are in small enough proximity to disturb it
so, conclusion - let leave overkilling with Donuts for lesser regs around
2. benefits of dual mono arrangement are
- much harder ending in situation of having ground loop, with clumsy constructed source ( having commoon GND for both channels)
-well, first one being enough ; again - due to nature of Good Gemini regs (nothing fancy, in fact, just decent enough in complexity and decently executed) even with common Donut - crosstalk between channels will be negligible, but ...... what's price of 2pcs of 10-20VA Donuts?
so - if idea of having 1KV Donut laying somewhere in the corner, being connected to tiny boxes with umbilical - is having all your buttons pushed - be my guest ....... who am I to stand in a way of someone's Happiness
but that's just wasting of money and wasted opportunity to make a distinction between decent enginering practice and Audiophoolery
again - I have nothing against overkill and Audiophoolery - when being well informed choice - I even like that and I'm practicing that ........ but I made transition from Choiceless Sucker to Sucker by Choice, long time ago
so, conclusion - let leave overkilling with Donuts for lesser regs around
2. benefits of dual mono arrangement are
- much harder ending in situation of having ground loop, with clumsy constructed source ( having commoon GND for both channels)
-well, first one being enough ; again - due to nature of Good Gemini regs (nothing fancy, in fact, just decent enough in complexity and decently executed) even with common Donut - crosstalk between channels will be negligible, but ...... what's price of 2pcs of 10-20VA Donuts?
so - if idea of having 1KV Donut laying somewhere in the corner, being connected to tiny boxes with umbilical - is having all your buttons pushed - be my guest ....... who am I to stand in a way of someone's Happiness
but that's just wasting of money and wasted opportunity to make a distinction between decent enginering practice and Audiophoolery
again - I have nothing against overkill and Audiophoolery - when being well informed choice - I even like that and I'm practicing that ........ but I made transition from Choiceless Sucker to Sucker by Choice, long time ago
Dual mono external supply it is then
Big Iron always pushes my buttons - short man syndrome
Johnny Cash - Big Iron - YouTube
Thank you
