So Hugh and X,
Are you two in agreement or disagreement? In any case, I guess I'll go with a happy medium of 5uf as the input capacitor for both the Alpha 20 and Alpha Nirvana!
Best,
Anand.
Are you two in agreement or disagreement? In any case, I guess I'll go with a happy medium of 5uf as the input capacitor for both the Alpha 20 and Alpha Nirvana!
Best,
Anand.
We are in agreement of course. It just had to do with what you define as acceptable bass roll off. 4.7uF is a good compromise. 10uF will get you subsonic HT style bass you probably don’t need.
Hello Anand!
I just want to pass on a few thoughts....
I originally had a small film input cap (3.3uF) installed when my AKSA Lender Preamp was first fired up. After testing and listening to make sure all was good, I swapped out the 3.3uF cap for an 8.2uF. Surprise! There was an improvement that was heard in the low end. But, my main speakers can play pretty low to hear/feel the difference. I couldn’t tell the difference when my bookshelf speakers were used.
So, I’ve use at least 8.2uF with all my AKSA based builds since then.
Cheers and Happy New Year too ALL!!
Vunce
I just want to pass on a few thoughts....
I originally had a small film input cap (3.3uF) installed when my AKSA Lender Preamp was first fired up. After testing and listening to make sure all was good, I swapped out the 3.3uF cap for an 8.2uF. Surprise! There was an improvement that was heard in the low end. But, my main speakers can play pretty low to hear/feel the difference. I couldn’t tell the difference when my bookshelf speakers were used.
So, I’ve use at least 8.2uF with all my AKSA based builds since then.
Cheers and Happy New Year too ALL!!
Vunce
Finally the PS is starting to look like a PS 🙂
It's something old with something new:
a classic CLC with new LT4320 bridges (IPP040N06NAKSA1) and transformer snubbers
Next step: add the transformers and put it all in a case.
Greetings and a Happy New Year !
Danny
It's something old with something new:
a classic CLC with new LT4320 bridges (IPP040N06NAKSA1) and transformer snubbers
Next step: add the transformers and put it all in a case.
Greetings and a Happy New Year !
Danny
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Happy New Year to you Danny!
That is impressive PS. It will go into a separate enclosure or with the amp?
That is impressive PS. It will go into a separate enclosure or with the amp?
It will go in the amp, it's 4U 400mm case and it just fits,
the transformers need to be mounted vertically.
the transformers need to be mounted vertically.
Thanks,
the wooden board makes it easy to mount everything on it.
The underside of the board has a channel milled in which I'll route the mains wire from the back panel with the softstart to the front panel with the transformers.
With all that iron that wooden board is mandatory for reinforcement.
the wooden board makes it easy to mount everything on it.
The underside of the board has a channel milled in which I'll route the mains wire from the back panel with the softstart to the front panel with the transformers.
With all that iron that wooden board is mandatory for reinforcement.
Hiyas Brains-trust - I was running my ABBB amp (~3 A bias) for about 4 - 5 hours but didn't notice that one FET cpu cooler fan was actually off till the end of the listening session (!!!!!!).
I quickly shutdown the amp and rectified the fan issue (loose connection it seems) - restarted and verified correct operation through visual check with an oscilloscope and 1 khz sine wave input.
Should I consider replacing the affected FET? Or will it be ok?
IXYS datasheet says Tjmax is 150 deg C, and voltage/current in ABBB application is definitely within safe operating region.
In my haste to turn off the unit, I didn't take any thermal measurements - but the respective heatsink was too hot too touch (not frying pan hot, but definitely too hot to keep a finger on).
I was running in brand new speakers (KEF Q950's) - quite glad I didn't blow them up on first listening!
I quickly shutdown the amp and rectified the fan issue (loose connection it seems) - restarted and verified correct operation through visual check with an oscilloscope and 1 khz sine wave input.
Should I consider replacing the affected FET? Or will it be ok?
IXYS datasheet says Tjmax is 150 deg C, and voltage/current in ABBB application is definitely within safe operating region.
In my haste to turn off the unit, I didn't take any thermal measurements - but the respective heatsink was too hot too touch (not frying pan hot, but definitely too hot to keep a finger on).
I was running in brand new speakers (KEF Q950's) - quite glad I didn't blow them up on first listening!
Hi Aive,
I'd would watch that channel carefully, and measure the quiescent. If it is still 3A, no more/less, and none of the leads have not unsoldered, I'd conclude that it's OK. Listen to it critically for a few days, and if you hear anything different wrt the other channel yes, I'd replace the IXYS device. But these are very tough devices, you have have dodged a bullet........
This is a reminder that the fan is crucial and has to be running each and every time these amps are fired up. And fans collect dust too, so check 'em every couple of months.
Hugh
I'd would watch that channel carefully, and measure the quiescent. If it is still 3A, no more/less, and none of the leads have not unsoldered, I'd conclude that it's OK. Listen to it critically for a few days, and if you hear anything different wrt the other channel yes, I'd replace the IXYS device. But these are very tough devices, you have have dodged a bullet........
This is a reminder that the fan is crucial and has to be running each and every time these amps are fired up. And fans collect dust too, so check 'em every couple of months.
Hugh
I have done the same thing twice. Once I thought I turned it off for the night but only turned one channel off (mono blocks) and turned fan off. It sat like this for over 24hrs. The copper pipes on the CPU coolers turned gold (how that happens not sure). Short story is they still work fine. I took MOSFET out of cooler to replace the cooked thermal grease. That’s it.
Now I leave fan on after I turn off and turn fan off hours later or next day. Better that than another episode.
It’s scary but those IXYS are tough.
Now I leave fan on after I turn off and turn fan off hours later or next day. Better that than another episode.
It’s scary but those IXYS are tough.
Thanks X - I don’t feel as foolish now 😛
Those noctua fans are too quiet - can’t tell if they’re running unless you visually check
Those noctua fans are too quiet - can’t tell if they’re running unless you visually check
So I have an oddball, longshot question. In the first post, there is a render, likely from JP that shows some tall thin mounting tabs for resistors, next to the big power resistors on the board. I'm building a new version and planning on paralleling a few Mills MRA5's to get the values I need, and these would be super handy.
I thought I remembered seeing an early bom with the parts numbers on it, but can't seem to find that now. If anyone has the part number, I would be super stoked!
Thanks~
Gable
I thought I remembered seeing an early bom with the parts numbers on it, but can't seem to find that now. If anyone has the part number, I would be super stoked!
Thanks~
Gable
Hi Gable,
We are going to have to ask JPS64 what parts those are. I don’t see it in any of my BOMs either. I think you helped me to make a BOM/shopping cart for Alpha 20 way back when?
We are going to have to ask JPS64 what parts those are. I don’t see it in any of my BOMs either. I think you helped me to make a BOM/shopping cart for Alpha 20 way back when?