Correct. In the link, he describes the design and states it is fully assembled, tested and is for one channel (only ONE INPUT and ONE OUTPUT):
Best,
Anand.
Hi Daanve,
If you are worried about mosfet life, I would suggest you use 280W mosfets, FQA40N25 and FQA36P15, and use active cooling. Then your concerns are completely put to rest.
HD
If you are worried about mosfet life, I would suggest you use 280W mosfets, FQA40N25 and FQA36P15, and use active cooling. Then your concerns are completely put to rest.
HD
I am going with the larger Fairchild MOSFETs as well. Running 45w is not too much more than the 35w normally considered safe for IRP240/924, but why not for about same cost.
Hey X,
In another thread you mentioned how this amp could be built as a 5 watt version. Could it also be built as say a 20 watt amp and with it's greater efficiency put out less heat than would be typical for a 20 watt class A? I ask because I am looking to build something to use in place of my ACA that has more output but no greater heat dissipation requirements.
In another thread you mentioned how this amp could be built as a 5 watt version. Could it also be built as say a 20 watt amp and with it's greater efficiency put out less heat than would be typical for a 20 watt class A? I ask because I am looking to build something to use in place of my ACA that has more output but no greater heat dissipation requirements.
Yes, I think we could come up with a 20w version. Probably drop the supply voltage to +/-22v would give you about 20w. I think Hugh could run an LTspice simulation to zero in on the settings and voltage and bias current. IIRC, the ACA runs at 24v and 1.25A so this is 30w dissipation. In order for a +/-20v amp to make less than 30w, max bias current would be about 680mA. That seems low - so I am pretty sure we can’t make 20w Class A amp that dissipates only 30W.
1.2A x 40V would be 50W. A manageable amount of heat for a small CPU cooler or a 4U x 300mm heatsink, maybe even 3U.
1.2A x 40V would be 50W. A manageable amount of heat for a small CPU cooler or a 4U x 300mm heatsink, maybe even 3U.
The PCBs have been shipped and I should have them in 3 days. Unfortunately, that is past the weekend so won't really be able to put it together until next weekend.
Yes, Spiggs,
A low power 20W can be done with two 20V rails; a bit of work at the simulator and I will have it up in a couple of days......
Hugh
A low power 20W can be done with two 20V rails; a bit of work at the simulator and I will have it up in a couple of days......
Hugh
Thanks X and Hugh. I think that may be what I am looking for. I want to move up from my ACA but have been put off by the typical 80 - 100 watts per channel of heat dissipation that seems to be the standard for a 20-25 watt Class A amp. My main amp needs to live in a partially enclosed cabinet so I need to be mindful of how much heat it puts out so I don't create an oven in the entertainment center. I would be quite honored if you took the time to work up a 20 watt version.
Hi hugh, while we're at it, can i use a dual 18vac donut with the stock circuit? In my area, i get almost 26vdc from a simple CRC filter without load.
Regards.
Regards.
Yes, EmeryBB, if you forgo the SLB regulator (and the amp has reasonably high PSRR) you could use a couple of 18Vac secondaries to good effect.
That would give you around 25V rails, and your power from the 39W version running 1.7A quiescent would be 33W//8R.
Otherwise, the SLB would drop another 4V from each rail, giving you 21V each rail, and with a 1.35A quiescent you would a total dissipation of 56.7 watts, very reasonable with a 300x100x50 heatsink, and audio power of 27.5W, more power than you'd need I believe. But very cool........
HD
That would give you around 25V rails, and your power from the 39W version running 1.7A quiescent would be 33W//8R.
Otherwise, the SLB would drop another 4V from each rail, giving you 21V each rail, and with a 1.35A quiescent you would a total dissipation of 56.7 watts, very reasonable with a 300x100x50 heatsink, and audio power of 27.5W, more power than you'd need I believe. But very cool........
HD
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Downsizing to 50W dissipation to fit in a fanless 3U chassis would definitely get the best of both worlds.
Great work here. 🙂 Just wondering if this amplifier might be a good fit with a pair of Delaware DM947 Monoliths?
That would be very comparable with USSA-5.
Different schematics, but though I have Exicons as well as selected IRPF pairs, I tend to prefer the "audio" lateral power mosfets.
Abslolutely, could each of the two Hifi2000 3U 40x300mm heatsinks dissipate ~50W for a stereo set?
