Matching ZTX450 across Aleph channels?

spzzzzkt · 19th February 2008, 10:08 PM

Hi

I was wondering if there was any advantage or point to matching the CSS ZTX450 across channels in the Aleph amps? Would this improve matching of current draw or bias between channels? In the mini-A schematic the parts in question are q4 and q5..

cheers
Paul

metalman · 19th February 2008, 11:53 PM

In the schematic you show, Q4 acts as a safety valve to limit the amp's max output current in the event that the outputs are shorted. Q4 doesn't take an active role in the circuit unless an upset condition occurs.

Therefore, you won't find any benefit in matching Q4 to Q5. Likewise, you wouldn't find any benefit in matching Q4 in one channel to Q 4 in the other channel.

There can be a benefit to matching Q5 left channel to Q5 right channel in order to get better matching between the current response of the Aleph constant current sources. However, most builders have included potentiometers in the Aleph CCS that allows us to trim the current response and bias level. These adjustments are discussed in detail in Nelson's Zen series of articles.

Cheers,
Terry

spzzzzkt · 20th February 2008, 02:09 AM

Thanks metalman!

I have a small stack of ztx450 I order fearing I'd fried a couple when my amps went up in smoke, so I might match up a couple to replace Q5's. I'll check the zen articles also.

cheers
Paul

amphead123 · 21st February 2008, 03:35 PM

Nelsons Zen articles? I don't think i've ever heard of these. Where can i find these?

dave_gerecke · 21st February 2008, 03:48 PM

Hello Amphead, take a look at www.passdiy.com. Mr. Pass has graciously created this website to post different projects he has done, along with details about making your own version of these.

Peace,

Dave

spzzzzkt · 21st February 2008, 07:06 PM

And as I'm discovering in the Zen Variation series of articles there very detailed explanations of how things the Aleph Constant Current Source (CSS) function.

The original Zen articles are in the Legacy section fwiw...

http://www.passdiy.com/amps.htm
http://www.passdiy.com/legacy.htm

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19th February 2008, 11:53 PM	#2
metalman diyAudio Member Join Date: Jun 2003 Location: Calgary, Alberta	In the schematic you show, Q4 acts as a safety valve to limit the amp's max output current in the event that the outputs are shorted. Q4 doesn't take an active role in the circuit unless an upset condition occurs. Therefore, you won't find any benefit in matching Q4 to Q5. Likewise, you wouldn't find any benefit in matching Q4 in one channel to Q 4 in the other channel. There can be a benefit to matching Q5 left channel to Q5 right channel in order to get better matching between the current response of the Aleph constant current sources. However, most builders have included potentiometers in the Aleph CCS that allows us to trim the current response and bias level. These adjustments are discussed in detail in Nelson's Zen series of articles. Cheers, Terry

20th February 2008, 02:09 AM	#3
spzzzzkt diyAudio Member Join Date: May 2005 Location: Melbourne	Thanks metalman! I have a small stack of ztx450 I order fearing I'd fried a couple when my amps went up in smoke, so I might match up a couple to replace Q5's. I'll check the zen articles also. cheers Paul

21st February 2008, 03:35 PM	#4
amphead123 diyAudio Member Join Date: Feb 2008	Nelsons Zen articles? I don't think i've ever heard of these. Where can i find these?

21st February 2008, 03:48 PM	#5
dave_gerecke diyAudio Member Join Date: Dec 2007 Location: Vermont	Hello Amphead, take a look at www.passdiy.com. Mr. Pass has graciously created this website to post different projects he has done, along with details about making your own version of these. Peace, Dave

21st February 2008, 07:06 PM	#6
spzzzzkt diyAudio Member Join Date: May 2005 Location: Melbourne	And as I'm discovering in the Zen Variation series of articles there very detailed explanations of how things the Aleph Constant Current Source (CSS) function. The original Zen articles are in the Legacy section fwiw... http://www.passdiy.com/amps.htm http://www.passdiy.com/legacy.htm

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