Aleph J illustrated build guide

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#9,341
Zen Mod said:
keep C1, increase value to 4u7 (max 10uF)

phase - frequency dependent attenuating is in most cases resulting in changing phase of signal

C1 forms hi-pass filter with 22K
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kylefitch said:
ZM, can you clarify this for an amateur like me please. How does the cutoff frequency moving from 7.2Hz to 1.5Hz effect the bass response when both are in the inaudible range?
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phase twist - that's single thing I see as possible high-pass filter

with some speakers, not going low, that would be inaudible

604 is going low
 
#9,344
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#9,347
Hello, I built two aleph j boards. One works, the other doesn't. There is 20.5 volts on the output of the failing board. 0 volts through R16 R17 R18 R19. Q2 25 volts CE, Q4 2.5 volts CE. Q1a 25 volts DG, Q1b 15 volts DG. Q1a and Q1b 15 volt DS. What should i look for to fix? Thank you.
 
#9,349
R8 is 1K ohm. 8.5 volts across R8, 9.1 volts across D1.
IMG_20230607_065028.jpg
 
#9,352
I bought the transistores kit from Diyaudiostore.
I had already measured the 4 Jfet and the result of my instrument was "broken". I measured with the recommended method "GS to V+ and 100 ohm resistor, and the result was 1.60/2.00 volts across the 100 ohm resistor. Mr. Pass told me I did something wrong in my mesure, but it wasn't the first time that I measured the Jfet. Maybe I will buy new ones.
IMG_20230506_215913.jpg
 
#9,355
I'm confused. Do I understand this correctly?

1) all 4 jfets show as having an error on your tester and measure 1.6 to 2V across 100 ohm resistor using standard shorting of gate to source pin method
2) 2 of these were in one Aleph J board that worked while the other 2 were in the other Aleph J board that didn't work

I sometimes use a transistor tester similar to yours. The socket on mine is a bit flakey so sometimes it takes a few shots to get a good connection, but when it does, it gives reasonable measurements with 2sk170/2sj74 jfets. (Mine would give a Vgs with a low current, something approximating Vp.)
 
#9,357
Dennis Hui said:
I'm confused. Do I understand this correctly?

1) all 4 jfets show as having an error on your tester and measure 1.6 to 2V across 100 ohm resistor using standard shorting of gate to source pin method
2) 2 of these were in one Aleph J board that worked while the other 2 were in the other Aleph J board that didn't work

I sometimes use a transistor tester similar to yours. The socket on mine is a bit flakey so sometimes it takes a few shots to get a good connection, but when it does, it gives reasonable measurements with 2sk170/2sj74 jfets. (Mine would give a Vgs with a low current, something approximating Vp.)
Click to expand...
All right.
I'm confused too. 😵
 
#9,359
oloppolo said:
🙂 done of course!View attachment 1181524
maybe it's out of range of the tool
Click to expand...

if you try it on all 4 fields of socket, then .........

at least on mine, one of 4 fields is having all "1", "2", "3" contacts

then each of 3 remaining fields is being exclusively just one of (1,2,3) contacts

practically - you can test 2pin and 3pin parts only on one field

I can't see from pics which of these is right one
 
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