what needs to be matched in an aleph-p 1.7?

jarthel · 6th July 2007, 01:43 AM

I have searched the forums and I got bits on info (not a lot of thread in regards to matching mosfet/transistors in the aleph preamp) the but wasn't sure if they are correct (and I need some to verify what was written). I also looked at passdiy and all I can see is the pearl phono preamp article.

In this thread: http://www.diyaudio.com/forums/showt...ht=#post26680, ignatz talked about close matching of the 2 signal IRF610. So only those 2 IRF610 needs matching? If yes, could you tell me which are the signal IRF610? how about the IRF9610? do these need to be matched at all?

In the same thread, Mr. Pass has said that the transistor doesn't need to be matched. I assume he is talking about the ZTX devices?

Thank you very much for the help

GRollins · 6th July 2007, 02:32 AM

Q16 and Q19 (the ones that the signal goes into and out of) are the ones to match. All the rest either don't matter or are self-adjusting.
(And no, this one isn't self-evident unless you've built stuff like this before, so I ain't fussin')
Carry on.

Grey

jarthel · 6th July 2007, 02:42 AM

thank you very much

GRollins · 6th July 2007, 03:00 AM

Given the design of the circuit--meaning the resistance between the two halves (R51, R66, and a pot which doesn't seem to have any designation)--you do not technically have to match those two devices. However, the lower the resistance between the two halves (meaning the pot approaching zero), the more difference it will make. Given that each side has a dedicated current source and is cap-coupled at the output, there's a lot of leeway for mismatched devices.
You'll get somewhat better performance if they're matched.

Grey

jarthel · 9th July 2007, 12:05 AM

Quote:

Originally posted by GRollins
Given the design of the circuit--meaning the resistance between the two halves (R51, R66, and a pot which doesn't seem to have any designation)--you do not technically have to match those two devices. However, the lower the resistance between the two halves (meaning the pot approaching zero), the more difference it will make. Given that each side has a dedicated current source and is cap-coupled at the output, there's a lot of leeway for mismatched devices.
You'll get somewhat better performance if they're matched.

Grey

just a question. how do I know the 2 halves are balanced? From what you have written above, it seems I to turn the 2k pot. But what do I measure to know they are balanced?

I hope the question is clear.

Thank you very much

6th July 2007, 01:43 AM	#1
jarthel diyAudio Member Join Date: Jan 2002 Location: somewhere in Australia	what needs to be matched in an aleph-p 1.7? I have searched the forums and I got bits on info (not a lot of thread in regards to matching mosfet/transistors in the aleph preamp) the but wasn't sure if they are correct (and I need some to verify what was written). I also looked at passdiy and all I can see is the pearl phono preamp article. In this thread: http://www.diyaudio.com/forums/showt...ht=#post26680, ignatz talked about close matching of the 2 signal IRF610. So only those 2 IRF610 needs matching? If yes, could you tell me which are the signal IRF610? how about the IRF9610? do these need to be matched at all? In the same thread, Mr. Pass has said that the transistor doesn't need to be matched. I assume he is talking about the ZTX devices? Thank you very much for the help

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6th July 2007, 02:32 AM	#2
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Q16 and Q19 (the ones that the signal goes into and out of) are the ones to match. All the rest either don't matter or are self-adjusting. (And no, this one isn't self-evident unless you've built stuff like this before, so I ain't fussin') Carry on. Grey

6th July 2007, 02:42 AM	#3
jarthel diyAudio Member Join Date: Jan 2002 Location: somewhere in Australia	thank you very much

6th July 2007, 03:00 AM	#4
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Given the design of the circuit--meaning the resistance between the two halves (R51, R66, and a pot which doesn't seem to have any designation)--you do not technically have to match those two devices. However, the lower the resistance between the two halves (meaning the pot approaching zero), the more difference it will make. Given that each side has a dedicated current source and is cap-coupled at the output, there's a lot of leeway for mismatched devices. You'll get somewhat better performance if they're matched. Grey

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