Dear Zen Mod,
Thank You for the answer.Just more question.What a modern output mosfet's from a good manufacturer would be used instead of 244?
Regards,Chelg
The IRFP240 MOSFET is a perfect fit for the Aleph amplifiers, is in current production and available at an affordable price. Why complicate things trying to find alternate devices?
@chelg
as Grimberg wrote - IRFP240
and , as I said numerous times - feel free to use one IRFP150 instead of two pcs of IRFP240 , as long you keep it cold enough (50C at sinks and decent thermal interface - read -mica and goop or better) and as long you keep dissipation under 50W/piece
as Grimberg wrote - IRFP240
and , as I said numerous times - feel free to use one IRFP150 instead of two pcs of IRFP240 , as long you keep it cold enough (50C at sinks and decent thermal interface - read -mica and goop or better) and as long you keep dissipation under 50W/piece
Dear Grinberg,
Thank You for the answer. Do all regimes of output cascade remain the same as in the original Pass circuit?
Regards,Chelg
Thank You for the answer. Do all regimes of output cascade remain the same as in the original Pass circuit?
Regards,Chelg
The Aleph 3 uses two pairs of MOSFETs, each pair matched within .01V. One pair is driven by the differential input (first stage), while the other pair provides the bias current. I am not sure about the meaning of "output cascade".
You can use IRFP240 to replace the IRFP244 devices without making any changes to the other components.
You can use IRFP240 to replace the IRFP244 devices without making any changes to the other components.
If you are planning to build an Aleph 3, you might want to read this thread:
http://www.diyaudio.com/forums/pass-labs/267857-aleph-design-reloaded.html
You may be especially interested in post #9.
http://www.diyaudio.com/forums/pass-labs/267857-aleph-design-reloaded.html
You may be especially interested in post #9.
Could you get a little crazy and use 2 pcs irfp150?
you mean - two pairs of IRFP150 ?
of course, and of course they need to be matched
issue/possibility pretty much covered in this thread
blowing fuses
I am troubleshooting the PSU of my Aleph J. The PSU has two toroidal transformers of 250VA each with two separate PSU boards from the diyaudiostore. I am using 4 monolithic bridge rectifiers and a total of 264,000 microfarads across the two PSU boards. Upon power up, the LEDs on the PSU boards light up and I can very briefly measure the expected positive and negative voltages. But, then the CL-60 thermistors which connect PSU ground to chassis (and the IEC safety earth terminal) get hot enough to smoke and the fuses blow. I am using a pair of 2.5A slow blow fuses. Reading this forum has shown me that I should be using a pair of 5 Amp slow blow fuses which I intend to order. But, would fuses which are not sufficient lead to the thermistors smoking? This all occurs without the amplifier circuits attached.
Any suggestions will be greatly appreciated?
I am troubleshooting the PSU of my Aleph J. The PSU has two toroidal transformers of 250VA each with two separate PSU boards from the diyaudiostore. I am using 4 monolithic bridge rectifiers and a total of 264,000 microfarads across the two PSU boards. Upon power up, the LEDs on the PSU boards light up and I can very briefly measure the expected positive and negative voltages. But, then the CL-60 thermistors which connect PSU ground to chassis (and the IEC safety earth terminal) get hot enough to smoke and the fuses blow. I am using a pair of 2.5A slow blow fuses. Reading this forum has shown me that I should be using a pair of 5 Amp slow blow fuses which I intend to order. But, would fuses which are not sufficient lead to the thermistors smoking? This all occurs without the amplifier circuits attached.
Any suggestions will be greatly appreciated?
Yes, of course, meant 4 per side, 8 total for stereo.
Thanks for the link, it's a good read. Apparently I read it once since I posted in it 😱
I built a bulb tester and found 5A slow blow fuses. When I turn on the power, the bulb lights up indicating a short somewhere. So, I tested each PSU separately by de-soldering the primaries. When tested in separation each PSU turns on the bulb. I see many millions of Ohms between PSU ground and the rails. I am not sure what to do next.
Aaron
Aaron
I'm not familiar with these PSU pcbs ... I mean - I can't see markings on pads
please take some better pics - so we can see details - how you wired that
please take some better pics - so we can see details - how you wired that
Please see the attached photo of a PSU PCB as requested. Though, I am beginning to think I may only have had a fuse issue. I have stepped through the components from transformer to PSU PCB (on the left side) adding back and testing. The transformer appears normal as do the bridge rectifiers. When I solder the PSU PCBs back into the circuit I do see the bulb tester turn on briefly on power up but I suspect what I am seeing is the supply caps charging. I think previously I assumed that any light from the bulb tester indicated a short. After I regained my confidence in the circuit, I turned the power on without the bulb tester in place but with the 5 Amp slow blow fuses and all appears fine now. I still am unsure why the thermistors between PSU ground and chassis/IEC earth got so hot when the 2.5 Amp fuses blew. Perhaps I fixed a problem when I de-soldered and re-soldered the components. Any thoughts?
Thank you,
Aaron
Thank you,
Aaron
Attachments
I am waiting for the chassis to warm up before rechecking the bias and offset for both channels. All seems fine!
Thanks,
Aaron
Thanks,
Aaron
might try a variac to power up with, your amp might be showing a short because your caps are not charged up yet , you're cl 60/fuse can't handle the load and smoked.
A slow start up is best ,check the store for a soft start!
A speaker cutoff is good to have also🙂
😀
NS
A slow start up is best ,check the store for a soft start!
A speaker cutoff is good to have also🙂
😀
NS