Aleph J illustrated build guide

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#2,721
for latest tests - your preamp is suspicious

there is no logic for right channel to behave properly open and shorted ,then fed with preamp berserked ....

either try other preamp , or try with preamp's output which drove left channel without troubles ...... in other words - be sure that you use same preamp's out channel for both amp's channels testing

only that way you can be sure you're operating with same entities all the time , changing just DUT
 
#2,722
6L6 said:
At this point tie ALL of the grounds to one of the ground blocks on the PSU

PCB power, speaker returns, CL-60 and the grounds of the RCAs. Starground. Everyting in one place.
Click to expand...

To get you right.....
You want me to wire ALL Grounds to a ground point on PSU?!

Even from neg. speaker posts and RCA grounds?!
-I can run an extra wire from each channel pcb ground to PSU ground?!
Then even RCA and speaker return would be connected to PSU ground?!

Like this?!
 
#2,723
Zen Mod said:
for latest tests - your preamp is suspicious
Yes very suspect!

there is no logic for right channel to behave properly open and shorted ,then fed with preamp berserked ....

either try other preamp , or try with preamp's output which drove left channel without troubles ...... in other words - be sure that you use same preamp's out channel for both amp's channels testing
......Switched the channels....even fed with left channel from preamp right channel behaves the same.....

only that way you can be sure you're operating with same entities all the time , changing just DUT
Click to expand...
 
#2,724
Ok...I found a major mistake....and fixed it...
I’d placed the washer on right RCA between ground lug and nut :headbash:
and not between chassis and ground lug....
This obviously the major problems with the right channel...

Hum is still there but It seems to be much less....
Maybe I’ll try 6L6’s Star grounding!

How quiet you can get an Aleph J?!
 
#2,730
mcgreg66 said:
This is where I want to be.....
But why I have so much trouble with getting rid of that hum?!
Is it a problem of the psu PCB or just the normal issues with him?!
Click to expand...

problem is , besides few mistakes you did , you're not following methodical approach ... even if you are claiming you did

build it by pictures from 6L6's build tutorial , and it will behave
 
#2,731
I’m not claiming anything.
I tried to work methodically and make a clean built.
Although I’m no newbie in DIY, I don’t have the technical understanding some of you have
.....so I need to go with built guides and I’m thankful for every help if problems come up.
Whatever....

I managed to connect ALL grounds to one spade ground on PSU.
Now the right channel is nearly silent but left still has hum.
But even wiring looks pretty messy now.

I will go through the built guide and try to find out what I missed!

Thanks all
 
#2,733
I think it's been mentioned before, but don't forget to try rotating the transformer to find the position of minimum hum. On my F5 build, I could get the very slight hum to pan from left to right channel by rotating the transformer. Finally found the null point where no hum is detectable. This takes some time and assumes you have long leads on the transformer. It also may help to mount the transformer in a vertical position using an L-bracket.
 
#2,734
WKCox said:
I think it's been mentioned before, but don't forget to try rotating the transformer to find the position of minimum hum. On my F5 build, I could get the very slight hum to pan from left to right channel by rotating the transformer. Finally found the null point where no hum is detectable. This takes some time and assumes you have long leads on the transformer. It also may help to mount the transformer in a vertical position using an L-bracket.
Click to expand...

I will try ....
Although I think it’s a problem of unshielded transformers because of their electromagnetic field...
Mine is a shielded one...
 
#2,736
Noise measurement

I think part of the problem is we're often describing noise/hum
issues qualitatively. My 'quiet' on my speakers may not cut it
for someone with super efficient horns, for example.

Looking at the FW amp comparison page:

FIRST WATT PRODUCTS

noise figures in uV are given. At the very least this gives you
an idea of what is possible with a decent build.

Has anyone tried measuring their amp for noise? How should one
go about doing it?

Thanks,
Dennis
 
#2,737
Dennis Hui said:
I think part of the problem is we're often describing noise/hum
issues qualitatively. My 'quiet' on my speakers may not cut it
for someone with super efficient horns, for example.

Looking at the FW amp comparison page:

FIRST WATT PRODUCTS

noise figures in uV are given. At the very least this gives you
an idea of what is possible with a decent build.

Has anyone tried measuring their amp for noise? How should one
go about doing it?

Thanks,
Dennis
Click to expand...


I had a friend measure mine though I don't remember the uV figure(s). My AJ was really low since I used an encapsulated transformer (Toroidy) and CLC. He also tested my M2, while still low (Toroidy transformer as well), it had a tad bit more noise (ripple) due to me using a CRC. I followed all the grounding practices laid out in the build instructions. Both amps were in good uV figures overall though with no issues on his 100db horns
 
#2,740
WKCox said:
I think it's been mentioned before, but don't forget to try rotating the transformer to find the position of minimum hum. On my F5 build, I could get the very slight hum to pan from left to right channel by rotating the transformer. Finally found the null point where no hum is detectable. This takes some time and assumes you have long leads on the transformer. It also may help to mount the transformer in a vertical position using an L-bracket.
Click to expand...

The L-bracket works well, and it allows you to use a short case - see post 2016.
 
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