After having purchased this boards and transformer kit quite a while ago. Interest in balanced amps growing, so here goes.
First question, (I love demonstrating my idiocy to the worldwide interweb):
When BOM says for example 2E2, this same as 2.2R?
Plenty more dead horse beating to come.
Russellc
First question, (I love demonstrating my idiocy to the worldwide interweb):
When BOM says for example 2E2, this same as 2.2R?
Plenty more dead horse beating to come.
Russellc
My google search indicates 2.2R = 2E2, = 2.2E, so I am good there.
I am noticing a few of the caps no longer available from digikey or mouser as the were in days of yore.
Questions will be asked concerning appropriate replacements once I have determined that I can't find originals, and find said replacements.
Russellc
I am noticing a few of the caps no longer available from digikey or mouser as the were in days of yore.
Questions will be asked concerning appropriate replacements once I have determined that I can't find originals, and find said replacements.
Russellc
Much appreciated. First, to lessen dead horse questions, I am going through the cookbook, the "clean" and "unclean" thread, and looking up from various sources the listed parts. To those I cant find I will find substitute and inquire if good enough or keep looking.
Plan is to build Shunty Power supply first....
Russellc
perfect timing - I'm in the same boat
I recently re-discovered my Pumpkin and Shunty boards (with matched Qs), wrapped in some unintelligible newspaper
, and have just started looking at the cookbook/BOM/various threads trying to get up to speed.
Like you, I'm looking to get the Shuntys up and running first. It has been ages since I built anything, so getting back into it will be challenging, but I could use a preamp right now so I'm pretty motivated. I did spend some time today looking at some of the options for case, switch, volume control - I'd be interested to hear what choices you make along the way and I'm happy to reciprocate.
Tod
__________________
diy: gainclone - pearl phono - jordan js92x monitors - 6n1p headphone amp
I recently re-discovered my Pumpkin and Shunty boards (with matched Qs), wrapped in some unintelligible newspaper
, and have just started looking at the cookbook/BOM/various threads trying to get up to speed.Like you, I'm looking to get the Shuntys up and running first. It has been ages since I built anything, so getting back into it will be challenging, but I could use a preamp right now so I'm pretty motivated. I did spend some time today looking at some of the options for case, switch, volume control - I'd be interested to hear what choices you make along the way and I'm happy to reciprocate.
Tod
__________________
diy: gainclone - pearl phono - jordan js92x monitors - 6n1p headphone amp
I recently re-discovered my Pumpkin and Shunty boards (with matched Qs), wrapped in some unintelligible newspaper
Like you, I'm looking to get the Shuntys up and running first. It has been ages since I built anything, so getting back into it will be challenging, but I could use a preamp right now so I'm pretty motivated. I did spend some time today looking at some of the options for case, switch, volume control - I'd be interested to hear what choices you make along the way and I'm happy to reciprocate.
Tod
__________________
diy: gainclone - pearl phono - jordan js92x monitors - 6n1p headphone amp
That sounds great to me, particularly since you wish to go for Shunty power supply first. As stated, I am currently figuring out which caps are no longer in stock, checking alternative sources and then if nothing else ding donging poor zenmod to see if my selections are better. Feel free to comment here if you want, I will post "approved" parts and source and when I am ordering.
Resistors first, then caps, I bought the full package with all the transistors from Zenmod, so I shouldnt need them. I understand there are no orphan parts and they are easy to find if you didnt.
Another thing are the heatsinks, I really dont want to just use a chunk of aluminum, want something nice and neat like the build picks show. I think they used fischer sinks, dont know if they are available on this side of pond, I havent started looking.
Once PS done, Pumpkin building in same order, then case, then connectors, selectors and attenuators. Currently re-reading all the threads, cookbooks, etc.
Let's get this done!
Russellc
Sounds good! I did order the full package with transistors, so I'm set there, too. I did a lot of reading today trying to corral the info, and did a bit of looking for transformers (don't know if you've got those sorted) - there's a place I need to call tomorrow that might have a nice option.
I did find this parts list on diyaudio earlier, assume you've seen it, too, but it is where I was going to start (from this thread: http://www.diyaudio.com/forums/pass-labs/115912-my-own-pumpkin-preamp-construction-4.html).
Tod
Tod and Russell,
In case you have not yet seen them, here are the pictures of my Shunty + Pumpkin build. The case was hand-made in my garage.
I intentionally left part of the original markings of the aluminum plate in the inside of the case. It reads "AMS 4027" and you can see that portion in the picture containing the uncut aluminum plate on the table saw. That is the "DNA" proof.
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-34.html#post4379549
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-34.html#post4379606
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-35.html#post4413152
In case you have not yet seen them, here are the pictures of my Shunty + Pumpkin build. The case was hand-made in my garage.
I intentionally left part of the original markings of the aluminum plate in the inside of the case. It reads "AMS 4027" and you can see that portion in the picture containing the uncut aluminum plate on the table saw. That is the "DNA" proof.
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-34.html#post4379549
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-34.html#post4379606
http://www.diyaudio.com/forums/pass-labs/103130-pumpkin-preamp-perfect-f4-35.html#post4413152
grimberg - Inspirational! I do like the cleanliness of having the xformers in the case, and the result is very nice - I'm not sure I have the tools to do that kind of fabrication (chop saw but nothing for cutting large plate), but you have given me something to think about. And I'll read through that thread to see what issues you had.
What are the dimensions of your case?
Tod
It's a zip file, so maybe the phone can't open that? Anyway, the post is:
[url]http://www.diyaudio.com/forums/pass-labs/115912-my-own-pumpkin-preamp-construction-4.html#post1438697[/URL]
I had been leaning toward an external PS chassis w/ umbilical, too, and definitely separate transformers for each Shunty. However, if a single-chassis solution, like grimberg's, can keep the transformers well-shielded, I might change my preference to that just because it is aesthetically more pleasing to me - I had been reading about shielding materials earlier today and it looks like there might be some pretty good options to minimize any effect from the PS side.
Tod
Last edited:
Thinking along the same lines concerning power supply. If I can, 1box is preferable.
Between Mouser and Digikey I have located the Yageo resistors and ordered most of them. I got more than needed as they are inexpensive and always handy to have.
I will compare to schematic and written materials, as some are gain related and may need varied.
Russellc
Between Mouser and Digikey I have located the Yageo resistors and ordered most of them. I got more than needed as they are inexpensive and always handy to have.
I will compare to schematic and written materials, as some are gain related and may need varied.
Russellc
ZenMod Inquiry:
Zenmod, I am looking at your notes on Shunty, where you comment on R21, R22, R23, R24, R23a, R24a, being needed to be lowered to 1E8 or 2E2.
Or, use metal oxide 1 watt resistors in these locations.
3 Questions, 1. if using the metal oxide 1 watters, I assume there is no reason to decrease value to 1E8 or 2E2?
2.The BOM made by shows them as 4E7, 1/4 watt "multicomp" 38K5353 from Newark... what is multi comp? Metal oxide? It also shows R7,7a, 15, 15a, 16, 16a, as well as above positions. What do these need to be? I missed any note of yours in regard?
3. WR1, 1a : shows 67f5829 Spectral unit, Will the typical Bournes pots not work here? Oh, BTW, I am using BOM linked to in post #7 parts list
Thanks for any help,
Russellc
Zenmod, I am looking at your notes on Shunty, where you comment on R21, R22, R23, R24, R23a, R24a, being needed to be lowered to 1E8 or 2E2.
Or, use metal oxide 1 watt resistors in these locations.
3 Questions, 1. if using the metal oxide 1 watters, I assume there is no reason to decrease value to 1E8 or 2E2?
2.The BOM made by shows them as 4E7, 1/4 watt "multicomp" 38K5353 from Newark... what is multi comp? Metal oxide? It also shows R7,7a, 15, 15a, 16, 16a, as well as above positions. What do these need to be? I missed any note of yours in regard?
3. WR1, 1a : shows 67f5829 Spectral unit, Will the typical Bournes pots not work here? Oh, BTW, I am using BOM linked to in post #7 parts list
Thanks for any help,
Russellc
Last edited:
those resistors are current inrush limiting - use whatever you have in drawer , more ohms - more W needed
say that 1W MOX are ideal
regarding BOM - I hate and despise BOMs , they're much less universal than ppl think ; I didn't made that one , so I can't reply on BOM related specific question
just read what I wrote in Cookbook , use your brain while searching on vendor site ........ that way you'll learn much more than blindly following someone else's list
if in doubt - post link here , and I'll help
now - specifically :
R21, R22, R23, R24, R23a, R24a - 1R5 to 4R7 , 1W MOX - ideal
R7,7a, 15, 15a, 16, 16a - value as written ( do not change) , plain 600mW MF (that would be metal film)
pots - multiturns , screw on top - just take a look at pic in Cookbook , check on pcb are pins in line or triangled
On the pots, I couldnt figure out why the Spectrol unit from Newark, when most of the other parts were from Digikey and mouser, thought maybe it was a special unit!
This is one pre I want to stay working instead of blown smokey wrong parts.
I have a nice, and sizable case in mind. Not wanting to cheap out on this one.
Oh, and those pots are 5K, so bournes pots like on other DIY pass Amps? I have Bournes 5 K on hand. I notice the "BOM" notes the Spectrol unit has "64 W pins" so I wondered. As you are creator of Pumpkin Shunty, I am sure you know well what is sufficient!
Russellc
The case is 17.25" x 14.25" x 3". The transformers are from Antek Inc. and have electrostatic shield. That shield combined with the aluminum wall separating the transformers from the circuit boards, made for an absolutely quiet pre-amplifier.
Regarding power tools, I only used the table saw with a Freud blade for non-ferrous metals and a drill press. Many members of this forum have ordered pre-cut aluminum plates from Online Metal Store and seemed happy with their products.
Which Antek are they? May as well get them, I have used Antek in all my Pass projects Except the BA-3 amplifier, had one on hand from a F5 T group buy.
Also, what heatsinks did you use?
Russellc
Last edited:
The Antek transformers are AN-0240 - 25VA 40V. And I need to correct something I said earlier: they DO NOT have shields. Reviewing my build notes I remembered that the lack of shield was the reason I decided to add the wall, however, I never tested the pre-amp without it. The wall may not be necessary after all. I had the material handy and it was really easy to add the wall while building the case.
I purchased the heat sinks from https://www.buerklin.com/en, as suggested in the Shunty/Pumpkin manual.
I purchased the heat sinks from https://www.buerklin.com/en, as suggested in the Shunty/Pumpkin manual.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.