Does anyone know how the medical grade Triad trafos perform under load? Hoping that 250VA 24V donut per channel should work nicely here for Firstwatt-based amps (+/-24V), and not too much excessive voltage.So for the typical 25w Class A amp, use dual 200VA 22v trafos one per channel. Note that some brands like Antek sag more than others so step up one more notch to 24v. But maybe a Talema or Toroidy is fine at 22V. Yes, dual secondaries not center tapped. One more thing, it never hurts to go up one more notch in VA rating either so dual 300VA would assure you of even better performance.
I used 300 va 22 volt Anteks and I have a bit of excess voltage. I think you may have too much excess voltage at 24 volts.
Just so happens that I have the exact configuration you’re asking about, I’ll connect a load to the SLB and check voltage. Unloaded output is +/-32.5VDC.Does anyone know how the medical grade Triad trafos perform under load? Hoping that 250VA 24V donut per channel should work nicely here for Firstwatt-based amps (+/-24V), and not too much excessive voltage.
Attachments
Vunce, those Wago terminal blocks look awesome. What series are they, or do you have a link to some?
Yeah, the Wago 221 connectors ROCK!! I found a Wago mounting bracket that holds 2, 3 and 5 sized connectors. Makes the wiring very neat.
WAGO 221 Lever-Nuts 75pc Wire Connector Assortment Pack with Case https://a.co/d/dNY51vY
https://www.wago.com/us/rail-chassis-terminal-blocks/mounting-carrier-221-series-24-12-awg/p/221-501
WAGO 221 Lever-Nuts 75pc Wire Connector Assortment Pack with Case https://a.co/d/dNY51vY
https://www.wago.com/us/rail-chassis-terminal-blocks/mounting-carrier-221-series-24-12-awg/p/221-501
Vunce,Yeah, the Wago 221 connectors ROCK!! I found a Wago mounting bracket that holds 2, 3 and 5 sized connectors. Makes the wiring very neat.
WAGO 221 Lever-Nuts 75pc Wire Connector Assortment Pack with Case https://a.co/d/dNY51vY
https://www.wago.com/us/rail-chassis-terminal-blocks/mounting-carrier-221-series-24-12-awg/p/221-501
WAGO connectors do rock ! Love the execution. Really wanted to build those into my boards in lieu of faston's but darn if my BOM cost didn't skyrocket. Looking forward to getting many many free samples from WAGO @ IMTS this year.
Nah, no large sale. Just happened to find another forum member selling a pair. 🙂When did you all hear about these Triad medical grade 24v trafos? A big sale I missed perhaps?
24v is probably good for 27vdc under load with an SLB. Perfect for something like Alpha Nirvana or LuFo or SuSyLu.
Sounds like ~27VDC shouldn't be a problem for a SissySIT build. I'm guessing the MOSFET may run a bit warm, but I've also read that it's not horrible to err on higher voltage as opposed to lower -- so long as it's sufficiently heatsinked?
I connected a dummy load to simulate 1.7A for each SLB power rail.Does anyone know how the medical grade Triad trafos perform under load? Hoping that 250VA 24V donut per channel should work nicely here for Firstwatt-based amps (+/-24V), and not too much excessive voltage.
Output = +/-28V5
Turns out I'd have to lower bias current after all if I were to end up with 27VDC+ rails.
I'd like to get closer to get closer to your standard Firstwatt-based PSU (which is 23VDC I think), so I think many shoot for 24V.
Thoughts on going with this 22VAC from Toroid? They have an omega bracket for easy mounting (and shielding?) which is cool. However, these seem to be 117V primaries and my current apartment hovers around 119~120, so that may bump up just a hair?
Or, should I just go with 300VA Antek 20V if I'm trying to minimize excess voltage?
I'd like to get closer to get closer to your standard Firstwatt-based PSU (which is 23VDC I think), so I think many shoot for 24V.
Thoughts on going with this 22VAC from Toroid? They have an omega bracket for easy mounting (and shielding?) which is cool. However, these seem to be 117V primaries and my current apartment hovers around 119~120, so that may bump up just a hair?
Or, should I just go with 300VA Antek 20V if I'm trying to minimize excess voltage?
Hi Alan,I am trying the SLB on my Aleph J mono amps and am getting a large spike into the speakers when I shut the amps down. This doesn't happen when I power the Aleph J with the standard First Watt power supply, nor when I power my F6 boards with the SLB. Any idea why this happens with the Aleph J, and is there any way to alleviate it short of installing speaker protection boards?
Thanks,
Alan
I'm having the same turn-off spike in my recently completed SLB->Aleph J amplifier. For now, I connect speakers after amp is on and disconnect before shut-down. Wondering If you ended up installing speaker protection?
No, I didn't. I am going to try to back down the rails to ~24 volts. If that doesn't mitigation the issue, I'll go back to the standard first watt power supply that I was previously using.Hi Alan,
I'm having the same turn-off spike in my recently completed SLB->Aleph J amplifier. For now, I connect speakers after amp is on and disconnect before shut-down. Wondering If you ended up installing speaker protection?
I’ve been thinking about your Aleph J/SLB turn-off spike noise, I wonder if you added some capacitance at the SLB output it would slow the power rails down at turn-off similar to a standard First Watt CRC psu.
Before you lower the voltage, add a 10000uF cap across each power rail. As built per schematic the output caps are 220uF, add the new caps in parallel to these.
Before you lower the voltage, add a 10000uF cap across each power rail. As built per schematic the output caps are 220uF, add the new caps in parallel to these.
Another thing I've noticed with this combination... with speakers connected the positive rail bleeds down very quickly while the negative rail takes some time. With speakers disconnected both rails bleed down together, very slowly.
This asymmetry in the bleed down was what I suspected as the source of the turn off thump. If we ask ourselves why the asymmetry is not there when it is on, it would indicate that the input stage swings positive when no more power is supplied. It might be that increasing the bulk capacitance above the positive input stage rail may help. Maybe increase the value of C4?
https://www.diyaudio.com/community/attachments/aj-skema-bw-png.330720/
https://www.diyaudio.com/community/attachments/aj-skema-bw-png.330720/
- Home
- Group Buys
- The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB