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Old 5th October 2008, 08:32 PM   #1
Bengali is offline Bengali  United States
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Default Aleph P.17 Power Supply


I've built up two Aleph P1.7 power supplies. Each with it's own transformer(Antek 32V 50VA) for a dual mono block. The fet
has a heat sink.

How long does the it take for the voltage to stabilize?
With No Load, when I power it up, it takes about 25 secs to reach
the 60volts. Then it continues to increase about 0.1volts
about every minute.

I let it sit for about 10 minute, one reads 60.80volts
and other 61.85volts. There is a 3.3K bleeder on the last cap.

I thought the zeners was suppose to keep it regulated
at 60volts. is the one with 61.85 volts too high?

Why 1volt difference? part tolerances?

I wanted to have a dual mono block for the P1.7.
With one supply being higher than the other, would
this cause the volume of one channel to be higher as well?

What do you suggest? Thanks for your help.
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File Type: jpg p1.7 pwr sch.jpg (38.5 KB, 473 views)
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Old 5th October 2008, 09:44 PM   #2
Zen Mod is offline Zen Mod  Serbia
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those voltages are completely OK ,and sayed thermal behavior of circuit , also ;

don't worry - just proceed
my Papa is smarter than your Nelson !
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Old 6th October 2008, 01:54 AM   #3
Bengali is offline Bengali  United States
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I went ahead and hooked up the preamp to the power supply. Current draw per channel is about 70mA, does this sound right?

The DIP switch settings are all off. I shorted the (-) and GND on the input. I put a 1Khz 1Vpp in and tweaked the trim pot to get 1Vpp on the output. Now am I suppose to get Positive Half of sine wave on (+) of output and Neg. Half on (-) of the output?

I get the full sine wave on both + and - of the output. Ref is GND.
Is this because I shorted the input and using single ended?

I'll be using a single ended cd source on the input of the preamp. preamp balanced output to the dantimax balanced attenuator, to a balance mini-aleph.

I thought XLR is suppose have half sine wave on + and - ?


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Old 6th October 2008, 03:24 AM   #4
Bengali is offline Bengali  United States
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I hope someone can help clarify the hook up between the P1.7 and other amps(like mini-A or F5).

If I uses signal ended source(CD player), must I use single ended output from preamp to amplifier? or can I use balanced between preamp and amplifier?

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Old 6th October 2008, 07:40 AM   #5
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you can use balanced P1.7 is kind of converter in every "direction" you can think of.

Ba to Se
Se to Se
Se to Ba
Ba to Ba

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Old 6th October 2008, 05:12 PM   #6
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congrats for your Aleph P and i hope you will set some pics for us

just one advice: for minimum distortion figure also short the - output to gnd if you intend to use it in single end mode.

A curiosity:
have you tried to measure noise at the output with the oscilloscope (input shorten and gain set ti 1X)?
Do hear any kind of noise/hiss on the tweeter (i mean with your ear right by the speaker) when you turn the volume on clockwise position?
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Old 6th October 2008, 06:24 PM   #7
Bengali is offline Bengali  United States
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Thanks replying.

right now, I'm just powering up and doing smoke test :-)

looks okay so far. (-) on output should show inverted
full sine wave, correct?

what do you set for 1x gain? do you use 1.35db attenuation?

right now, all my dip switch settings are OFF, that's give me
9db Attenuation?

I plan to use balanced output to balanced input of Mini-Aleph
for now until I build F5.

I'm using the dantimax 1K balanced attenuator on output.

only thing I don't like is I don't know where to put IR receiver
without making it look crappy. since there is no already made
IR lens filter for panel mount. thinking of just mounting it externally.

I can't tell you of distortion/hiss yet since not fully wired up
for functional testing. will get there.

sure, I will send some pics when completed.
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