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Old 5th June 2013, 11:47 PM   #2371
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Quote:
Originally Posted by still4given View Post
after all this time.
Hey, matey.
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Old 6th June 2013, 02:42 AM   #2372
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Originally Posted by grimberg View Post
Terry,

Eric has spent a lot of time and effort documenting his Aleph-X builds and adventures. He also used hifiZen's boards and his site is a great source of information.

Aleph-X 100w Amplifier Construction Notes
There are tons of information there, especially in the "first power up" section. In particular, I would recommend checking voltages across R23 and R25. This should be about 4.7v or so. Check voltages across all MOSFET source resistors. These should each be the same and in the 0.4 to 0.5v range. Check both relative (across speaker terminals) and absolute ( each speaker terminal to ground) offset.

It seems odd the the speaker load would cause a problem. I've done some pretty awful things to my amps, and the only thing that resulted in actual damage was when I recently shorted a few things on the board with my DMM probes. Have a look at your power supply, too. Make sure all of your connections are still firm. Measure voltages at your PSCaps, and check ripple voltages as well on each cap.
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Last edited by Eric; 6th June 2013 at 02:45 AM.
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Old 6th June 2013, 02:29 PM   #2373
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Thank guys, you are the best! That is exactly what I was looking for. I guess I need to work on my search engine skills. I couldn't for the life of me find that wiki page.

I had forgotten how sensitive this amp is to temperature. Turns out, I had the amp sitting on a stand right in front of the little wall shaker that cool my work shop and it was mainly blowing on the left side heatsink. Once I turned it off, the voltages on the left side more closely matched the voltages on the right. Now that I have the info again I will let it warm up well and go back through the settings and make sure everything is a close as I can get it.

I let the amp play for about 4 or 5 hours yesterday and it got better as the day progressed. It is actually a very pleasant amp to listen to but it is surely weaker in the bass than all of the other amps I have built. I wasn't expecting that when I built it. To be fair it is the lowest power of all of them. I built it with a 1200VA 12-0-12 AC trafo so I am getting around 15V rails. I also used MTW32N20E outputs rather than the units called for in the wiki so maybe they have less bass.

Thanks again, Terry
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Old 6th June 2013, 11:48 PM   #2374
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I got a chance to play around with my amps some more today. I think I finally found what everyone was excited about. As I bumped up the volume of each amp the AX started to gain on all the others. The louder I drove it, the better it sounded. A couple of the other amps started clipping or sounded brassy but the Aleph really started to get nice. Pretty surprising that the weakest of the bunch shined the most when played loud. Very nice. These are the amps I was playing with. ES P101, Leach Low TIM, Symasym 5. Krell KSM 50 clone and of course the A-X. What fun!
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Old 7th June 2013, 02:32 AM   #2375
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Every now and then, I feel guilty about needing to installing a dedicated 30A breaker and a run of 10 gauge wire to power my trio of Aleph-X amps...

Then I sit down to listen

... and the guilt just melts away
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Old 9th September 2013, 06:30 PM   #2376
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hello
for some newbie
where to buy aleph-x pcbs
found information about hifizen boards but no information about any store or ebay auctions
kk boards are morally questionable to buy
could you recommend me any place to buy two for aleph-x high powered monoblock amp?
thx in advance
greetings
5hinka
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Old 9th September 2013, 07:00 PM   #2377
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Best bet is to post in the SwapMeet with a Wanted to Buy (WTB). Some show up every few weeks or so...
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Old 9th September 2013, 07:29 PM   #2378
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5hinka drop me a PM with your email address. I have a couple hifizen boards available.
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Old 20th October 2013, 03:55 PM   #2379
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Default Aleph-X, Asymetric waveforms from output

Input is a 1khz sine wave. I measured the outputs (one side connected to Ch1, the other side connected to Ch2, Ch2 is inverted and superimposed over Ch1) - There is a slight difference in amplitude and waveform shape.

I have 180mv across the output and about 90mv from each output to ground - can't seem to reduce these offsets (I'm guessing at this being due to FET differences at the bias current, mine were matched at a lower current). I can play with these later.

I had amplitude differences previously but searched through the forums and found that driving the amplifier from a single ended input could cause this (increasing the value of the "Macmillan" resistors reduces the effect but with side effects elsewhere (i.e. start-up DC offset)), so I added a DRV134 single ended to balanced convertor and tried to drive the AX inputs directly from that (i.e. without additional coupling capacitors) - I have already checked the amplitude of the DRV134 outputs and they are correct (so inputs to AX are definitely of the same amplitude).

I would greatly appreciate some assistance in trying to resolve this issue.
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Old 21st October 2013, 07:59 AM   #2380
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Default In case it's relevant...

It's a pretty much completely standard Aleph-X, i.e. just 4 fets running with 20v rails and with 10K Macmillan resistors on the group buy PCB.
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