Author Topic: Critical transistors in QSXM2  (Read 5181 times)

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Offline fantast

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Critical transistors in QSXM2
« on: January 06, 2012, 09:30:49 PM »
Well, not critical, but to have an eye at.
What do you think are the most important, where I need to use 1% metal film; R48 (I assume); R2 and R50 (I expect) and maybe R16/17 and R42/43?

For the RIAA the 2M7 might be the most critical one?

Kind regards
Claus
« Last Edit: January 08, 2012, 02:55:42 PM by peranders »

Offline peranders

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Re: Critical transistors
« Reply #1 on: January 07, 2012, 09:43:47 AM »
I think you should use metal film everywhere. The feedback resistors are the most sensitive I should think.
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Offline fantast

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Re: Critical transistors
« Reply #2 on: January 07, 2012, 01:18:06 PM »
So including the R35?

Offline peranders

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Re: Critical transistors
« Reply #3 on: January 07, 2012, 01:37:49 PM »
I'm out in the bush so you must enlighten me. Where is the R35 in the design?
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Offline peranders

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Re: Critical transistors
« Reply #4 on: January 08, 2012, 02:55:28 PM »
I'm back from the bush...  :-)

R34, R35 is not critical when it comes to tolerance. You could use other types there.
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Offline fantast

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Re: Critical transistors in QSXM2
« Reply #5 on: January 08, 2012, 08:52:25 PM »
Hi P-A,

thanks. Thought about it and got to similar conclusions.

Besides: Thanks for that great sounding prepre. I use it now with my JA and a Jensen Step-Up (selfmade from JT 347). The step-up is to keep my nerves calme; the JA will be cooked quite easily by any DC which goes back into the cardridge :|).
Togetherwith the step-up it's a great combination and I feel it is much clearer, more extended and faster than my Schönhut pre, that I used before.

Today I changed R93 (OK, I soldered some tulip pins in there as basis for putting in various resistors to test; wheras R93 is quite not a favorable position for such things :|).
I put it to 56k and connected the stage directly to my power amp (MX 10000) and it seems to work better than with the preamp in between (does not come as a surprise :?)

But I doubt if the prepre will be able to drive my full bi amp configuration (I did not connect the bass now..)

Do you think it can?

Many regards
Claus

PS: Will try to integrate some THAT300p shortly