I have some options for 12AX7 as well. Do you have any recommendations on what you've liked to use for V2?
I have quite a number of USA made GE and RCA options. I have a couple marked Holland that appear to be Amperex. And I have a single Gr. Britain (blackburn code) Mullard, which is what I've been using while I play around with the 6DJ8's.
Don't have any of those in the 12ax7 variety unfortunately. Maybe I'll keep my eye open for one!
***NEWS***
Hi all,
As some of the eagle eyed amongst you may have seen, there has been an adjustment to the BOM.
The BF861B is now "end of life" and is no longer being manufactured.
Obviously this is very disappointing news but it's not all bad. We have identified an alternative Jfet - The 2SK932-22
I have made up a couple of MultiFET PCBs and installed them into my BB3. I am happy to go forward with these Jfets as there is nothing of note (sonically) that i am unhappy with.
These are very capable replacements and the best part is the Fets are a little bit cheaper too!
I'll add a part number later today or tomorrow.
Oliver
Hi all,
As some of the eagle eyed amongst you may have seen, there has been an adjustment to the BOM.
The BF861B is now "end of life" and is no longer being manufactured.
Obviously this is very disappointing news but it's not all bad. We have identified an alternative Jfet - The 2SK932-22
I have made up a couple of MultiFET PCBs and installed them into my BB3. I am happy to go forward with these Jfets as there is nothing of note (sonically) that i am unhappy with.
These are very capable replacements and the best part is the Fets are a little bit cheaper too!
I'll add a part number later today or tomorrow.
Oliver
Hi, my name is Vincent and I'm collecting all the bits and pieces for my build. Btw great news Oliver that a replacement part is available. You guys are geniuses.
I have a question about isolation kits for the regulators on the heatsinks. Is this necessary or can I just use cooling paste. I forgot to order them otherwise I would have just used those mounting kits.
Best wishes from the Netherlands,
Vincent
I have a question about isolation kits for the regulators on the heatsinks. Is this necessary or can I just use cooling paste. I forgot to order them otherwise I would have just used those mounting kits.
Best wishes from the Netherlands,
Vincent
Geniuses? I wouldn't go that far lol.....
If you don't isolate them onto the heatsink, you will short them out. It's not only about thermic transfer.
My pcb populated except for the output caps. I used 0.1% resistors and matched them to equal values. I was a little surprised how close values are but almost all were not the exact value. Plenty resistors for future projects..
I think I put the multifet board in the right way. I couldn't find pics here with the multifet board in place so I peeked at your Ebay listing Oliver. It occurs to me now that I could have used the data sheet of the fet...
You may notice the tube sockets are different from the Beltons so I had to improvise on grounding them. I plan to have the shields on them because I have them in a box anyway. And isolation on the heatsinks [emoji1303].
So now waiting on the transformer and saving some money for a nice pair of output caps. Great project so far!
I think I put the multifet board in the right way. I couldn't find pics here with the multifet board in place so I peeked at your Ebay listing Oliver. It occurs to me now that I could have used the data sheet of the fet...
You may notice the tube sockets are different from the Beltons so I had to improvise on grounding them. I plan to have the shields on them because I have them in a box anyway. And isolation on the heatsinks [emoji1303].
So now waiting on the transformer and saving some money for a nice pair of output caps. Great project so far!
That looks tidy, and yes the MultiFET PCBs are the right way round.
Where is your Transformer coming from?
I bought the Audiophonics, which is delayed by an extra month due to covid-19. Got a nice email though explaining it and offering cancellation. I still bought it because I think their configuration tool is quite special and I may want to use it for future projects. Hopefully I did it right with the center tap but I don't fully understand what the difference is with the double 9V 26-90 Chinese one.
I'm in the process of ordering, and looking for some clarification on matching.
I'm working on the premise that I should be aiming for 0.1% tolerance on the channel resistors (R1L, R1R etc).
The non handed resistors, (R1P etc) I'm assuming can be anything within the 1% tolerance band, as they won't affect channel balance and in any case there's nothing to match them to.
Am I correct in this of missing something obvious.
Many thanks
I'm working on the premise that I should be aiming for 0.1% tolerance on the channel resistors (R1L, R1R etc).
The non handed resistors, (R1P etc) I'm assuming can be anything within the 1% tolerance band, as they won't affect channel balance and in any case there's nothing to match them to.
Am I correct in this of missing something obvious.
Many thanks
Hi Patrick, you've chosen the same strategy as I did. Even in a batch of 20 0.1% I couldn't find a single exact value though. I used a Dmm and an lcr meter and used the closest equal pairs. There's the meter tolerance as well unless you have lab grade equipment. And 1% resistors for the power supply. I haven't finished it yet but I'm sure it'll be very good.
Best wishes, Vincent
@ all, I've read up upon rectifieds, transformers, dual windings and center taps and I get it now.[emoji1303]
Best wishes, Vincent
@ all, I've read up upon rectifieds, transformers, dual windings and center taps and I get it now.[emoji1303]
