Aleph 60 building thread

[Danger Mouse]

I also have some queastions maybe someone knows?

I plan to etch boards by myself how large should i do the traces for the outputstage? at the moment i only have 35µm pcbs at home
Or should i look for 70µm boards?

And for the outputstage i want to use IRFP240 should be no problem.
But how should they be matched?
Is it ok:
->if the 6 from CCS fits togehther and the 6 from the Gain Stage also fits together?
or is it recommended that all 12 of one channel are matched togehther?

I`m not sure because in my Aleph J clone i used matched Quads so all Transistors of one channel are matched😕

 

[sakellogg]

about a 1\4" you can always add solder or solder a wire to the trace for more current.

match the current fets to eachother. and output to eachother.

have fun.

 

[PKI]

Guys, do i really need a rectifier bridge in safety grnd-to-signal grnd like in F5 turbo psu schematics, or it is redundancy and CL-60 like in F5 is enough?

 

[Zen Mod]

........CL-60 like in F5 is enough........

 

[PKI]

Which is better left(smaller) or right(bigger)?

An externally hosted image should be here but it was not working when we last tested it.

 

[6L6]

Doesn't matter. Use what you have on hand.

If you must go to the store and buy more, I like the smaller ones, but only because of the color. (which might just be the photo...)

🙂 🙂 🙂

 

[PKI]

I have enough of either of them. Was thinking a big will help to emit some more heat 🙂

Hope will start one tomorrow!

 

[6L6]

The heatsink effect of the bigger washer is negligible - the reason for using fender washers is to make the screw pressure on the top of the transistor case as even as possible, so the transistors are very square and flat to the heatsink surface. That's where the heat transfer takes place - the metal side of the package.

 

[PKI]

Thanks! Yep, it was kinda joke 🙂

 

[PKI]

Just started the psu, it measures +/- 36V with no load.

An externally hosted image should be here but it was not working when we last tested it.

I will be firing up the amp tomorrow, any suggestion? It is not an F5, so not much to tune... Should i just measure dc offset and voltage across source resistors?

 

[Marra]

One channel at a time.

 

[PKI]

Ok, started it, but :-(... I have: +/- 33.7V rail, DC on output -6.2V, voltage on source resistors(1ohm) -- 0.35V. R8(R11) source of Q3. --5.2V, R14(R18) -- 4.75V.

(BrianGT boards notation).

So everything looks perfect except DC offset. My Q1 and Q2 are matched perfectly, but I have a 100k R8(R6) resistor, maybe it is it?

An externally hosted image should be here but it was not working when we last tested it.

 

[HIPCHECK]

Is that 6V of DC offset?
Is that at initial start up? Also, did it settle any after running for a few minutes?

 

[PKI]

Ok, i removed R8, DC offset dropped to -16mV, but after 3 min of working rising again, now it is -28mV :-(

 

[Zen Mod]

everything up to 100mV is considered as OK

still - lesser is better

 

[PKI]

Anything i can do to reduce it? My input pars were matched super close.

-35 mV still going up... :-(

 

[Zen Mod]

ya have Algar_emi's Aleph pdf ?

 

[HIPCHECK]

Let her run for a bit and settle down, and measure it then.

Like they said 35mv is not really "bad", but it will change after warmup so let her run some now.

Steve

 

[PKI]

everything up to 100mV is considered as OK

still - lesser is better

Is it pdf for an Aleph 30 in red and blue collors?

 

[Zen Mod]

.