if thermal interface is impeccable, try not to go above 45W per device
how it sounds, and what you are feeding with B. J2?
Iq is set to .668mV with 1R and .68R source resistors in parallel. So 1.65A Iq according to my calculations. At 26.9V, 44.4W per device?
Feeding the J2 with a WHAMMY with opa1612 currently. Would love some iron in the chain though, ZM. 😉 Reading up on small iron animals and such. 😀
Feeding the J2 with a WHAMMY with opa1612 currently. Would love some iron in the chain though, ZM. 😉 Reading up on small iron animals and such. 😀
Haha! C’mon Sync. I know you’ve been brought to the dark side too, living so close the Mighty ZM.
coincidentally - he's speaking of tube stage I made when I was a little kid
I've lost that knowledge, since becoming Old Fart
I've lost that knowledge, since becoming Old Fart
Well yeah.. 🙂
But I still prefer simple tubes over iron curtains. My faw one is with 12b4a..
Well... I told myself that I was going to wait until cooler weather, but I could not resist starting my SS Down BJ2.
A few (per usual) silly questions that I cannot seem to find while digging through the thread. Even worse b/c I already built the BJ2 with standard devices. 😱
Quick confirmation from Mighty ZM, please.
1) R110 // R114. You were kind enough to mount J101-J104. So clearly this is two pairs. Just confirming R110 => 68R and R114 => 82R
2) You've mounted an SMD (1 Meg?) in position R139 on the back of the board. I traced the circuit in an attempt find it on the schematic and/or its function. I could not find it on the schematic. It seems to run between the R101 R121 junction and the GND side of R103, I believe. Of course, I assume, that I simply populate the rest of the board and I can sleep well, but I'd love to know where I missed it on the schematic (total dodo) or its function (slight dodo).
Once again, thank you to Nelson Pass and CodyT for the SS devices and of course to Mighty ZM for all the help to learning greedy boyz.
Cheers!
Pic of parts. If anyone is ever considering whether it's "worth it" to order the full parts kits from ZM. My answer is a wholehearted YES! I've done several, and his selection of parts and labeling is superior.
Note: No need for the Toshiba JFETs in the pic. ZM mounted the input LTP. 😀
A few (per usual) silly questions that I cannot seem to find while digging through the thread. Even worse b/c I already built the BJ2 with standard devices. 😱
Quick confirmation from Mighty ZM, please.
1) R110 // R114. You were kind enough to mount J101-J104. So clearly this is two pairs. Just confirming R110 => 68R and R114 => 82R
2) You've mounted an SMD (1 Meg?) in position R139 on the back of the board. I traced the circuit in an attempt find it on the schematic and/or its function. I could not find it on the schematic. It seems to run between the R101 R121 junction and the GND side of R103, I believe. Of course, I assume, that I simply populate the rest of the board and I can sleep well, but I'd love to know where I missed it on the schematic (total dodo) or its function (slight dodo).
Once again, thank you to Nelson Pass and CodyT for the SS devices and of course to Mighty ZM for all the help to learning greedy boyz.
Cheers!
Pic of parts. If anyone is ever considering whether it's "worth it" to order the full parts kits from ZM. My answer is a wholehearted YES! I've done several, and his selection of parts and labeling is superior.
Note: No need for the Toshiba JFETs in the pic. ZM mounted the input LTP. 😀
Nice – can't wait to hear what you think of it! The only thing I recall needing to tweak with mine was the resistor value inline with the bias pot. Ended up needing a little more juice. But that's more device-dependent anyways, so not especially useful to you at this point 🙂
1. still - do not mount R110, R114
2. ignore; that's addition to avoid floating neg input in any circumstance
Definitely! Just hooked the "original" BJ2 back up, so I can compare it to the BJ2 with SS.
Perfect song title to describe the BJ2...There's Something In The Air...
I still can't get over how the music seems to emerge from all around. It is the most "spooky" amp I have. I dig it. Been listening to it all day while building.
Perfect song title to describe the BJ2...There's Something In The Air...
I still can't get over how the music seems to emerge from all around. It is the most "spooky" amp I have. I dig it. Been listening to it all day while building.
Way to go IAIMH! If you go back to posts 500-515 or so you’ll see my struggle with a few resistors to get the Iq and Offset dialed in. I ended up with 330R at R118 for Offset and 510R at R123 for Iq. Good luck! Curious to see where you end up.
Thanks!
I definitely read those posts. A bit more progress. Taking it slowly.
On another note... Nothing beats a quick snap with a phone and a zoomed in pic up on the computer screen for a final check after inspection and cleaning. My vision is terrible, so I solder using 2.5x "jeweler's glasses" over my prescription. I can swing in a 5x loupe to inspect after I solder each joint or set of joints, but I still caught a solder bridge on M101 using the pictures. Must have gotten lazy on inspection.
I try to ... check schematic, pull parts, check spec sheets for pin-outs as needed, stuff, inspect.
Some early porn of the front and back after inspection, clipping, fixing the solder bridge, cleaning, etc.
Now I have to make the tough choice of what amp to rob a PSU from or wait to build a new PSU. I think I'm going to take the original BJ2 boards out of the chassis and replace them with these for the most direct comparison.
Fun stuff.
I definitely read those posts. A bit more progress. Taking it slowly.
On another note... Nothing beats a quick snap with a phone and a zoomed in pic up on the computer screen for a final check after inspection and cleaning. My vision is terrible, so I solder using 2.5x "jeweler's glasses" over my prescription. I can swing in a 5x loupe to inspect after I solder each joint or set of joints, but I still caught a solder bridge on M101 using the pictures. Must have gotten lazy on inspection.
I try to ... check schematic, pull parts, check spec sheets for pin-outs as needed, stuff, inspect.
Some early porn of the front and back after inspection, clipping, fixing the solder bridge, cleaning, etc.
Now I have to make the tough choice of what amp to rob a PSU from or wait to build a new PSU. I think I'm going to take the original BJ2 boards out of the chassis and replace them with these for the most direct comparison.
Fun stuff.