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Old 3rd November 2005, 01:50 AM   #1
SteveA is offline SteveA  United States
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Default A4 Psu ?

I am building an Aleph 4. I plan to use a 35-0-35 tranformer with a CLC (68000-2mH-68000). Duncans PSU simulates an under load voltage of+/-42.6V. I assuming that it will run fine but with reduced power but would like to confirm. Is this correct?

Second question: the caps mentioned above are rated at 50V, is that enough margin or should I find higher rated caps?

Thanks,
SteveA
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Old 3rd November 2005, 06:27 AM   #2
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Hi,

the amp will work fine on 42V. Power will be reduced at 8 Ohms (voltage limited) but not at 4 Ohms (current limited).

The caps will work fine. 20% is a large enough safety margin.

Watch out when using inductors that they won´t be saturated.

William
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Old 3rd November 2005, 03:23 PM   #3
SteveA is offline SteveA  United States
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William-
thanks for replying. I have built an A5 with the same CLC (same caps and inductor) and the amp sounds great. The inductor is an iron core (Erse from Partsexpress.com) 16ga, 0.154R DCR and rated at "500 watt".

I've Googled saturation in pi filters but haven't come across anything that would tell me what to expect. I have too much to learn about electronics yet.

Many thanks
SteveA
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Old 23rd March 2006, 12:49 AM   #4
SteveA is offline SteveA  United States
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Default Update

After neglecting my Aleph 4 I finally got back to it. The power supply measured 43.2 V vs a simulated 42+. I have one channel (building as mono blocks) hooked up to the output devices.

Using a variac I gradually increased to roughly half rail voltage (20+ V). I monitored the voltage drop across the sense resistors (well sense on the negative rail and "non" sense on the positive rail) and saw, ultimately, 0.59V drop on both sides. This 0.59V seemed stable as I slowly increased the voltage. I would assume had I gone to full rail voltage I would still see the 0.59V drop on both sides. I'll get to that, just happy it passed the smoke test.

I did notice that when increasing variac setting the voltage drop on the sense resistor changed initially but, in time, moved back to 0.59V. The "non" sense resistor on the positive rail was steady at 0.59V. Had I monitored the sense resistor on the positive rail would I have seen the same behavior (ie, moving away from 0.59V for a brief time but eventually setting back to 0.59V)?

SteveA
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Old 23rd March 2006, 05:35 PM   #5
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Hi,

what you see are current changes. Since the current flows from plus to minus rail the voltage at every source resistor will change too.

William
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