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Pass Aleph 2 dual power modes?
Pass Aleph 2 dual power modes?
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Old 13th February 2018, 01:35 AM   #11
Blues is offline Blues  United States
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Originally Posted by raman15 View Post
Haha...Thanks folks for your responses. Brought a smile to my face.

There is no going back here. However I do see the schematics for the Aleph 5 and 2 are almost identical except for the bias and output stages. My thought was that can I offload these to a separate board and call it "configuration board" and very easily switch from Aleph 2 to Aleph 5? 300W in savings will help ...

Your thoughts.....
Replace your power transformers with ones that have dual secondaries. You can have switchable secondaries so you have both +/-45Vdc for Aleph 2 and Aleph 5 +/-35Vdc supplies.

Life simplified! Leap into the Warpspeed wormhole... http://www.6moons.com/audioreviews/warpspeed/1.html
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Old 13th February 2018, 01:49 AM   #12
Eric is offline Eric  United States
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Pass Aleph 2 dual power modes?
Now THAT's an elegant solution. There are two possible solutions: changing rail voltage and changing bias current. I was trying to think of a simple way to change bias, but I like this suggestion for the transformer better.
My DIY Basement Theater, Aleph-X Amps, Avro Open Baffle Speakers, LDR based BA-3 pre, Pearl II, highly modded Technics SL-1200, F4, M2, a40, several ACAs, FHXL, Tang Band 1772 bass-reflex
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Old 13th February 2018, 02:04 AM   #13
raman15 is offline raman15  United States
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Originally Posted by aspringv View Post
I'm not intrinsically against any of those things...

Thinking aloud here, but if you've a transformer with split primaries, you could have a selector switch that wires the transformer for 120/240V operation, thus halving the voltages on the rails when in 240V mode. That's about the cleanest solution I can think of.
Aaaah...Less is more! The KISS (Keep It Simple Stupid) principle. Yes the toroids are dual primary....and I have one unit open to the reconfigure the PSU board. Easy enough to test. Thanks Aspringv and Blues! I will try this out soon(hopefully) and post. The cost of 1 switch and an extra Thermistor is so minimal .....or maybe a pair of lightly used 750VA yoroids may show up for sale.

its been 30 years since i last dabbled in electronics, built amps etc. and this was and is so much fun. Life gets in the way.

btw on another note......if you own a pair of nice speakers and an Pass aleph...do crank up Muddy Waters "Folk Singer" ...or Miles Davis "Assenseur pour L'echafaud" ...or Diana Krall's "A Case of You" live in Paris........absolutely transcending....
My apologies for being all over the map
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Old 13th February 2018, 03:09 AM   #14
aspringv is offline aspringv  Australia
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Pass Aleph 2 dual power modes?
...and if you ever move country you'll be all good as well!

I'd maybe wait for another member or two to chip in on that idea. I'm no guru, but I can't see any reason it wouldn't work.
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Old 13th February 2018, 03:39 AM   #15
xrk971 is offline xrk971  United States
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Pass Aleph 2 dual power modes?
If you like the sound of the Aleph, then you like the harmonic signature of SE Class A amps, dominant 2nd harmonic, lower third harmonic, not much else. Try the Ranchu Aksa Quasi Class AB amp. It has the same harmonic structure (Hugh designed it to mimic a SE Class A amp). It runs 120mA bias from +/-35v supplies and is much more green.

The Dacz layout is proven and tested. Great sounding amp.

Very simple quasi complimentary MOSFET amplifier
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Old 13th February 2018, 04:18 AM   #16
aspringv is offline aspringv  Australia
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Pass Aleph 2 dual power modes?
Looks like the primary switching is a go-er. Feeding 120V to a transformer configured for 240V?

Edit : and thanks for the musical suggestions - I've an aleph 2 ish clone at home, so I'll get amongst your suggestions.
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Old 13th February 2018, 05:07 AM   #17
2 picoDumbs is offline 2 picoDumbs  Australia
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I recently had some transformers custom made like this, but there are multiple taps on the secondaries.
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
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Old 13th February 2018, 07:19 AM   #18
Zen Mod is offline Zen Mod  Serbia
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Pass Aleph 2 dual power modes?
before doing anything with rails , make a test with variac

I'm pretty sure that you're going to have troubles with DC offset at output
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Old 14th February 2018, 04:47 AM   #19
Andersonix is offline Andersonix  Sweden
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Pass Aleph 2 dual power modes?
A totally different way to save a lot of energy would be to switch on and off the amp using a 'music sensor' circuit like Martin Logan uses f.ex.
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Old 14th February 2018, 04:55 PM   #20
Nelson Pass is offline Nelson Pass  United States
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Pass Aleph 2 dual power modes?
If you adjust the bias current and/or rail voltages of the Aleph, you will also
need to adjust the DC offset at the output.
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