Aleph J illustrated build guide

[Soundhappy]

@ Diyers

My Aleph J pcb's is ready stuffed so i attached mosfets to heat sinks and
try how they work with bench power supply for the first time.
I need short my green earth to (-) of bench psu ?
Psu output max voltage is +|- 24 V without load
but what output maximal current lock regulation 1,5 ~ 5 A of lab psu ?
Trimmer R27 is 68 kR value adjusted for start like in famous 6L6 guide.
Do i need use dummy 8 R 100 watts resistor ( my speakers are 8 R)
on speaker outputs for this bias & offset adjustement ?
RCA inputs are open or i connect them to my audio source ?
Have two voltmetres 1 for source resistor and 2 for offset.
Thanks for your kind response

 

[6L6]

Green chassis saftey earth does not need to be connected if using bench PSU.

If you have R27 set to 68K, leave it alone for now.

Power up and adjust offset to Zero. Measure bias. Change R27 if you want more or less bias.

You do not need load resistor on speaker output. Short circuit on input is helpful, but not strictly necessary.

Good luck!!

😀

 

[Soundhappy]

Good luck!! 😀

Thanks 6L6 all is much clear now 🙂
Happyly you are with us for councils.
I send tomorrow mesures picture
Greetings

 

[Soundhappy]

Transparent Sound

 

[folkdeath95]

Mine is almost ready too. I just have to double/triple-check all the wiring to be sure there's not mistakes.

 

[Soundhappy]

All is good and music are charming 😀
Work in progress next step PSU and i wait for Mills MRAO5F
wirewound source resistors after experiments with generic ones last evening
this no magnetic & no inductive Ayrton-Perry winding can be delicious
let's try them this is electronic cooking for sublime sound.

@ Folkdeath95
This photo from 6L6 are useful 🙂
Best regards

 

[folkdeath95]

On mine, input ground is soldered to -IN and a small cable connect it to GND.
I think it makes no differences. Does it?

 

[Zen Mod]

think

shortie is shortie

having contact on both ends

 

[Soundhappy]

The same potential in two situations

 

[Zen Mod]

whatever , if GND wire is soldered to GND pad , everything is groundier

 

[folkdeath95]

I know that was a stupid question.😀😀😀

Well, first test made 10 minutes ago, no smoke, no flames, everything seems to be OK. Bias is at 0.35V, offset à 0V and the amp is warming up.

The LED are brighter than expected, but it shouldn't be a problem. I'll see when the chassis is closed...

 

[Soundhappy]

Well, first test made 10 minutes ago, no smoke, no flames, everything seems to be OK. Bias is at 0.35V, offset à 0V and the amp is warming up.

@ Folkdeath95
Incrase led resististance value if you like
with the same or biger wattage
and light become less bright.
My amp was tested with lab psu only
do yours are connected to dedicated power supply ?
Good luck 😀

 

[folkdeath95]

I dont't have a bench PSU, so the amp is running on its dedicated power supply.
Concerning the LEDs, I'll see... With the lid in place, it seems to be OK and, as I don't have any LED on the front panel, the blue halo coming from the inside will act as an on/off indicator.😉

 

[Soundhappy]

It's run hot i can put hand on heat sink for 5 or 8s but no more
2 mosfets on left side are more cooler i think this is normal parameter.
I verify one more time bias & offset this evening
to see if they have drift or not ?
Anyway is better to take time for month or so and
bias at resonable maximum leater if needed 🙂
Greetings

 

[Zen Mod]

.....
2 mosfets on left side are more cooler i think this is normal parameter..........

all mosfets are having same dissipation

clarify , with pics if needed

be sure that they're all torqued the same

 

[WalterW]

Transparent Sound

Hi soundhappy, great work!

But in the end you are removing the long antenna wires from PCB to MOSFET's I hope?

You are going to build a lot of amplifiers I guess? I didn't know you were working on a Aleph J....
I thought your main interest was in VFET amps 😀

 

[folkdeath95]

It's run hot i can put hand on heat sink for 5 or 8s but no more
2 mosfets on left side are more cooler i think this is normal parameter.
I verify one more time bias & offset this evening
to see if they have drift or not ?
Anyway is better to take time for month or so and
bias at resonable maximum leater if needed 🙂
Greetings

My heatsinks were hot, but not burning. I could leave my hand on it without hurting myself.
I tried to measure the temperature with the thermometer I use to check if my son have fever. It just said "Hi". The temperature must be too high for this kind of device.😀 I have to find something else.

 

[wdecho]

If you can hold your hand on it for 8s it has passed the test. I would not worry much about it. My Aleph had the same result and I bought a IR thermometer gun because I was concerned like you and the temp was 55 to 58 c which is good.

 

[Dennis Hui]

I tried to measure the temperature with the thermometer I use to check if my son have fever. It just said "Hi". The temperature must be too high for this kind of device.😀 I have to find something else.

I tried that once and almost expected the thermometer to tell me to go to the nearest emergency room 🙂

I also used one of those thermometer probes on a cheap multimeter. Don't
think they're too accurate though...

Dennis

 

[jacco vermeulen]

go to the nearest emergency room

On the other hand, if you have a fever and use an outdoor thermometer, it would be both inaccurate and pretty d... painful.

I used the rain & wind today to lower the pool temperature.
Went from elevated body temperature to 30C in half a day (20,000gal), amazing.