Pics of my aleph 2 and problems!

[Russellc]

upper ones matched

lower ones matched

Thanks ZenMod, so I just need four Matched sets of 6 IRF244, as long as top 6 are all matched to each other, and bottom 6 are matched to each other, (even though the matched sets of 6 dont match the each other) All is good? Wow, I figured all 12 would have to be matched, so this is good news!
I was a little confused by the service manual's statment:

"The input Mosfets are match Vgs to within .01 volts, and the output Mosfets are in matched pairs within .1 volt, although production tolerance is typically .01 volt."

The idea of all 6 being matched makes sense to me, is Mr Pass inferring that
three matched pairs would work in place of a matched sextet? His next statement has to do with how tightly matched production seem to be...
I need as much in my favor as possible, so I think I will go for 4 matched sextets like you advise!

Thanks,
Russellc

 

[Zen Mod]

.....4 matched sextets.......

yup

 

[Melon Head]

Is there any chance your test speaker is faulty?
As already discussed, if you only have 20mV dc offset you should not be experiencing cone excursion problems

 

[KatieandDad]

You should fairly easilly be able to get all six FETs in each sextet within 1-2% of each other.

I used 50 devices to get five sextets, of which I used four and kept one set for spares.

 

[Coque]

Hello!

The speaker it's not faulty, I've checked it with a friend's aleph mini and it works great.

Tomorrow I'll check again the DC voltage and current draw betweeen output and ground, as you say 20mv it's not that much 8).
Also I've ordered some fet's for matching.

Thanks all for your interest, I'll keep testing!

 

[Russellc]

You should fairly easilly be able to get all six FETs in each sextet within 1-2% of each other.

I used 50 devices to get five sextets, of which I used four and kept one set for spares.

That's good news, in the service manual Pass states that they should be matched within .1 volt, but that production is typically .01 volt. This was some time ago, do these numbers for production still sound good? Sorry for the O.T.

Should I worry with matching closer that .1 volt?

Russellc

 

[Zen Mod]

PL ones usually were matched to 10mV

I think 100mV is too close to other Dark Side