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Aleph J illustrated build guide
Aleph J illustrated build guide
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Old 14th January 2020, 08:11 PM   #4491
elwood625 is offline elwood625  United States
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I did not stress the amplifier during the tests except to find the output voltage at clipping, 9.1v into 4 ohms.

The load I use is 4 ohms, output is 2v, for the measurements.
6L6 - There is no hum, I get the same 60 hz hash on my M2X when testing, not sure where it comes from. I spent a couple of weeks trying everything I could to get rid of it during the M2X testing, no luck. I'll retest this weekend with 0dBFS scale, I was going to increase the bias to 410 - 420mV. Living in central Wisconsin, more heat is a good thing this time of year.
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Old 14th January 2020, 08:34 PM   #4492
silasmellor is online now silasmellor  Denmark
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Aleph J illustrated build guide
Did you try using a balanced cable with the sleeve left unconnected to connect your amp to the interface?
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Old 15th January 2020, 01:00 AM   #4493
Extreme_Boky is offline Extreme_Boky
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I get faint 100Hz buzz from my Aleph J, pretty sure it is due to "insufficient" filtering.
My power supply PCB has 8 X 22,000uF/35V/105deg. The resistors (in CRC) are as per schematics: 4 X 0.47ohm on each rail.

I can hear this buzz if I place my ear right next to the woofer cone.

I think this buzz is expected and is "normal"

I also remember that 6L6 recommended "little" chokes for the power supply... I can not remember the value / the post where I saw it.... I think that with this choke, the buzz would disappear completely.
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Old 15th January 2020, 01:06 AM   #4494
Zen Mod is offline Zen Mod  Serbia
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Aleph J illustrated build guide
can't remember exactly how much original FW J had , but I believe it was usual arrangement of 8 x 15mF/25V for stereo PSU

so , you're good , not that you can't do more

post pictures , so we can see what's possible to do with your wiring

I have buzzing amps only on my T-Bed , which is deliberately made in pretty much worst while still functional fashion
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Old 15th January 2020, 01:32 AM   #4495
codyt is offline codyt  United States
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Quote:
Originally Posted by Extreme_Boky View Post
I get faint 100Hz buzz from my Aleph J, pretty sure it is due to "insufficient" filtering.
My power supply PCB has 8 X 22,000uF/35V/105deg. The resistors (in CRC) are as per schematics: 4 X 0.47ohm on each rail.

I can hear this buzz if I place my ear right next to the woofer cone.

I think this buzz is expected and is "normal"

I also remember that 6L6 recommended "little" chokes for the power supply... I can not remember the value / the post where I saw it.... I think that with this choke, the buzz would disappear completely.
Snubbers at the rectifier bridge helped quiet mine, also courtesy of 6L6
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Old 15th January 2020, 02:22 AM   #4496
Extreme_Boky is offline Extreme_Boky
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Quote:
Originally Posted by Zen Mod View Post
can't remember exactly how much original FW J had , but I believe it was usual arrangement of 8 x 15mF/25V for stereo PSU

so , you're good , not that you can't do more

post pictures , so we can see what's possible to do with your wiring

I have buzzing amps only on my T-Bed , which is deliberately made in pretty much worst while still functional fashion
Here are the photos... I tried playing with ground topology; this did not affect anything, the amp is quiet from that point of view.

As per codyt reply (thanks!!), I think the buzz might be as the result of a very little voltage drop caused by dual diodes I used. Once again, It is very faint and I think Nelson mentioned that FW Aleph J also had it... but was noticeable only when his customers were placing their heads inside the speaker cabinets


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Spent 3 days making this amp. The words can not describe how good this amp sounds...
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... lot No 1
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lot No 2
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Old 15th January 2020, 06:09 AM   #4497
silasmellor is online now silasmellor  Denmark
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Aleph J illustrated build guide
Im curious what the snubber configuration that worked for codyt was, trying snubbers on my f6 did nothing.
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Old 15th January 2020, 03:12 PM   #4498
codyt is offline codyt  United States
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Quote:
Originally Posted by silasmellor View Post
Im curious what the snubber configuration that worked for codyt was, trying snubbers on my f6 did nothing.
I believe the values are Cx220nf/Cs100nf/Rs18r, but unable to verify until later this evening. *6L6* will know, as he helped me with it. Transformer is a Antek 4218 (worked well on a 3220 too). Using monolith bridge rectifiers 35A 200V.
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Old 15th January 2020, 05:53 PM   #4499
mpa is offline mpa  United Kingdom
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Good news! After a month of waiting for some more LSJ74's to arrive in the UK Aleph J no2 is alive
It is currently cooking slowly waiting for another check of bias and offset.
I think I damaged the JFETs with the zip tie when I pulled them together as the leg broke off one of them when I desoldered it..
Finally I will be able to listen to them!
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Old 15th January 2020, 06:38 PM   #4500
JSA1971 is offline JSA1971  Canada
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Aleph J illustrated build guide
Quote:
Originally Posted by mpa View Post
Good news! After a month of waiting for some more LSJ74's to arrive in the UK Aleph J no2 is alive
It is currently cooking slowly waiting for another check of bias and offset.
I think I damaged the JFETs with the zip tie when I pulled them together as the leg broke off one of them when I desoldered it..
Finally I will be able to listen to them!
Congratulations, nice build! Which speaker protection boards did you use?
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