Sink > goop > ceramic > goop > mosfet. Gives a nice workable distance from sink to back of PCB for ZM mounting arrangement. Speaks are 92db DIYs ... they are lovely. We like to play records loud. I'm happy to go lower if that's the recommendation...setting Iq is super stable......seems there's an audible preference for the hot side when reading the thread....I'll do whatever....! Maybe see where the left side wants to live...
More importantly, here is a link to his speakers’ impedance/phase curves:
https://www.diyaudio.com/community/threads/open-source-monkey-box.327594/page-45#post-5865481
Best,
Anand.
I’m jealous…I’ve spent so much time trying to figure ways to push more current through one of my BJ2 4U/300 builds to see what, if any, difference it might make.
First attempt with small fans in bottom of case was a failure…fan noise was intolerable and didn’t move enough air to make any real difference.
I’ve only just gotten things to the point where I can push it up from 1A3 to about 1A5 on the bench and keep things around 55C.
It required bolting on additional heatsinks internally, opening up the baseplate under the amp PCBs which I raised up on taller standoffs for better air flow, changing the chassis cover to perforated aluminum and mounting two 3” fans to help pump air through.
I also installed a separate power supply, thermostatic controller and voltage regulator for the fans.
I’m hoping it actually runs a little cooler once I’m driving a load in a cooler environment. My workbench is in the furnace room…🤞
First attempt with small fans in bottom of case was a failure…fan noise was intolerable and didn’t move enough air to make any real difference.
I’ve only just gotten things to the point where I can push it up from 1A3 to about 1A5 on the bench and keep things around 55C.
It required bolting on additional heatsinks internally, opening up the baseplate under the amp PCBs which I raised up on taller standoffs for better air flow, changing the chassis cover to perforated aluminum and mounting two 3” fans to help pump air through.
I also installed a separate power supply, thermostatic controller and voltage regulator for the fans.
I’m hoping it actually runs a little cooler once I’m driving a load in a cooler environment. My workbench is in the furnace room…🤞
Attachments
Okay. Where to start? WOW.
I won't know anything about what I think I don't know
until a week or so when we swap back in M2X/Norwood. If "feelings" were the metric—Love would be the word. Sounds bloody glorious to me. Got a bit of the Aleph J thing going on (old feelings again of long lost elements of beauty but not wholly perfect)—but without the hyper-colorising? I suspect that when M2X is reinserted into the chain things may feel overly clinical. I kinda can't wait to know. Going back and forth without some time in between hasn't ever been very revealing to me...better to be patient. Loads of bass—and everything up from there—listened to a bunch of nice stuff—all vinyl—all jazz, different carts and phono pres... will broaden that over the week—check out the DACs w/ hires digital and see if there's any comments from the ladies during a movie or two. Also throw Iron Pre in there.Now, I'm getting around 136 degrees in key spots on the sinks with a laser. I can hold my hand on them no problem. The sink area just next to devices inside is ~100 degrees (without opening lid), bolt heads a few degrees over that... I suspect I'm good? Some super generous wise-guy is sending me a pair of R100s!! I could throttle down at that point or sooner if the consensus is I'm running too hot—sinks are basically 4U/400. Placement is a little aft due to Sissy ghost.
Yes—worth the effort!
Here's a crappy video (.zip file)—you can even hear some cooking in the background—pics later. The track that's being played had some warblely-tones on the electric...it's not an audio capture thing. Wish you all could be in the room! Nuts.
Yah! Niiiiiiiice...
I can't wait to fire them up tomorrow... bedtime for, not me...
I was re-reading the thread since I thought I remembered some parts swaps for "SemiSouth down"... haven't found that info yet—but I DID come across this which I clearly missed and mis-interpreted on the schematic (I think.)... Is this why I was able to dial in 1V8 (and higher) with no issue? I DID install R110 and R114....since I see 2 pairs of JFets in the input LTP...
It's all sounding awesome—so I assume all is well.
EDIT—Found it: R118=270R, R122=82R for SS Down.
I can't wait to fire them up tomorrow... bedtime for, not me...
I was re-reading the thread since I thought I remembered some parts swaps for "SemiSouth down"... haven't found that info yet—but I DID come across this which I clearly missed and mis-interpreted on the schematic (I think.)... Is this why I was able to dial in 1V8 (and higher) with no issue? I DID install R110 and R114....since I see 2 pairs of JFets in the input LTP...
It's all sounding awesome—so I assume all is well.
EDIT—Found it: R118=270R, R122=82R for SS Down.
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Wasn’t sure about the perforated aluminum…but what’s not to like about a sexy see through top? 😉
I can easily view my thermostatic display which tells me I’m running just under 53 C while pushing 1A5 when it settles into equilibrium.
Driving a load in a cooler room made quite a difference from it idling on the bench down in the furnace room at about 55.5C.
I could most likely try going for 1A7 I think.
I’m going to spend some time with it and then switch back to the amp running 1A3 and see if I think its worth the hassle to give that chassis the same treatment.
I can easily view my thermostatic display which tells me I’m running just under 53 C while pushing 1A5 when it settles into equilibrium.
Driving a load in a cooler room made quite a difference from it idling on the bench down in the furnace room at about 55.5C.
I could most likely try going for 1A7 I think.
I’m going to spend some time with it and then switch back to the amp running 1A3 and see if I think its worth the hassle to give that chassis the same treatment.
Attachments
I started out like you with an all IRFP version…then built a second (because I’m greedy…and want to play with multi-way ideas).
Then I converted the first one to Semisouth down to compare with the all IRFP version.
Then wanted to push more current, but my chassis were not up to it.
After much banging of head against case I finally got things cooling well enough (will only ever build with 4U/400or bigger in the future!)
In the process, I converted second amp to Semisouth down and cranked up the juice.
So now just enjoying it for a bit.
The speakers are a long term OB project that have evolved as much as the amps.
Sorry, no real build thread…just some posts here and there.
I was previously adding some Lii Audio Crystal 10 to them and came across the Liionidas documentation in the process.
Since they were already very similar I used it as a reference when I recently updated the fullrange drivers to the Sonido field coils.
Then I converted the first one to Semisouth down to compare with the all IRFP version.
Then wanted to push more current, but my chassis were not up to it.
After much banging of head against case I finally got things cooling well enough (will only ever build with 4U/400or bigger in the future!)
In the process, I converted second amp to Semisouth down and cranked up the juice.
So now just enjoying it for a bit.
The speakers are a long term OB project that have evolved as much as the amps.
Sorry, no real build thread…just some posts here and there.
I was previously adding some Lii Audio Crystal 10 to them and came across the Liionidas documentation in the process.
Since they were already very similar I used it as a reference when I recently updated the fullrange drivers to the Sonido field coils.