vvelt wrote:Still haven't received a PM in my inbox. That's how it goes.
Wait wait. Didn't you mention that you got the other one? I did as I did before and replied to your PM. I checked it just now and it looks to have been sent. So that seems odd that I get your PM's right away. At any rate, I did say "Yes" to what we were discussing there. While I would give you my email address through a PM, now I am not sure if you are going to get it. So I don't know how to proceed if the PM's are that unreliable on your end. I am getting your pm messages fine.
The Mundorf Supreme's are good. With the Darling you could use another 400v cap.
Yes, given to what I was reading and doing comparisons on your suggestions as well, I think I will give the Mundorfs a try.
I have JAN 1626 tubes as well. Bought them several years ago and will finally put them to use. The boxes are cool, dating them to wartime.
All around the JAN's just look good and I agree that even the box is nice. I do have other 1626 tubes, but they are not as nice looking as the JAN tubes. They date back to wartime because the 1626 tube (as well as the 1629 eye tube) were popular in a radio transmitter that was used on most WII B series planes such as the B-17 bomber. The radio was used from the 30's well through the 50's. So naturally the armed forces had thousands made.
For cathode bypass caps, the ones in the BOM should be fine and they are long life high temperature rated. However, there are audio grade lytic caps available from Nichicon and Elna. See this page on Mouser that lists the different audio grade caps from Nichicon:
https://www.mouser.com/new/nichicon/Nichicon-Audio-Caps
The KZ or "Muse" series are larger and their lead spacing won't match up with the board. However their FG or "Fine Gold" series will work fine for the power tubes as long as you keep them away from the hot cathode resistors. These are rated for up to 100v. The KA series are high temp rated and go up to 50v. I ordered these from Digikey since Mouser was out of stock.
Yes, I had noticed that they were out of stock as well. The 220uf cap is also a bit larger in diameter. Most of the other 'audio grade' electrolytics have different body dimensions. Unlike the coupling caps (on the board) that have multiple mounting holes, there is only a single pair for the electrolytic caps. So after putzing around for a half hour on the Mouser site looking for alternatives that don't seem to fit, I have decided to stick with what is specified. Besides it is something I could always swap out later on.
Question: If I DID go with the better electrolytic caps, at a SMALLER value, say 47uf in place of the 100's for C5 and C6, and 100uf for C3 and C4, then I have noticed some of the audio grade caps do fit. However, lowering the capacitance in a circuit was something I never did before. I was always told to go higher in value (when it comes to power supplies), but it seems that most of those audio grade caps don't fit on the board, but going with a smaller package...IE lowering the capacitance would have them fit. But what would that do to the sound?
UFG2A101MHM
UKA1E221MPD1TD
With small orders on Digikey you can select the cheapest shipping method which is USPS and as long as it's under a certain weight it will go out that way.
I've read where film caps are great for bypass, but they're just too huge.
Well, I have noticed the difference in that pre-amp I built. But yeah, they are pretty darn big. That circuit was mostly point to point. I made it from a Paia "Tube Head" preamp, but I was so disappointed with the results and it had a hum in it that I couldn't get rid of. It was one of those low voltage circuits that only had 50 volts on the tube plates. (It used 12AX7's). I was so pissed off that I ended up chucking the circuit board and reused the tubes and followed the schematic for an SRPP line stage. It had a more appropriate 240volt B+ too. I had a tapped volume control and made a loudness compensator and I put a couple other filters in. I did want to put in bass / treble controls, but the circuit didn't have enough gain for that. So it had a simple tone control, a loudness contour and I added a switch so I could switch between two sets of inputs. The results were fantastic, and even more so when I put the Solen caps in it.
Surprisingly, it seems that Paia still carries the Tube Head:
https://paia.com/proddetail.php?prod=9305HSR
BTW, those Vishay/Draloric resistors are interesting. After reading the specs on them, they say they are fusible/safety resistors. Bonus circuit protection!
I also wanted to ask you how you mount the boards in terms of standoffs. I am going to be needing those as well.
Regards,
Geo