Aleph 3? Project.

[Zoef]

Mr Pass posted a revision of the aleph 3 schematic. Now using some Toshiba 2sj313's. And some other changes are made. I took a long stare at the schematic and compared it with the kk schematic i got with the boards ( first post in this thread) . If i am correct the kk is exactly the same as the aleph 3 schematic of 1995. No.: pl40r02.501
On this schematic r113 is 47K and R114 750r. The revision shows 56k and 680r. Would it be a good idea to replace these as well?

 

[6L6]

R113 sets the AC gain of the CCS. Make that a 100K pot. R114 is in the bootstrap, not a bunch of difference between 680r and 750r.

 

[Zoef]

Ohh i feel terrible for asking, ( i'm a noob at these things [emoji15]) could you explain me what the purpose of this is, and why it's better to use the pot? I know i'm asking a lot. Need to do some extra reading.

 

[6L6]

Making that a pot has a direct effect on setting bias.

 

[Zoef]

Ah, making it possible to to adjust it you mean.

 

[6L6]

Yes.

 

[Zoef]

The irf9610's need to be matched at 20mA?
No harm in using 2SC2240 instead of MPSA18?

 

[Zen Mod]

if they're of same polarity , no harm

always take care of possible pinout difference , when making changes

 

[Zoef]

Implementing the revision of mr. Pass, would this be the right way to build the PSU if i would want to use 1 transformer for a stereo configuration?

 

[6L6]

Use 2 bridges per winding - that will lower mechanical hum in the transformer.

That PSU will be incredibly heavy - many Kg, with large transformer and 4 large chokes. You may want to consider a single PSU.

OR, build as monoblocks.

 

[Zoef]

Yes, that was the first plan. Monoblocks. I'm afraid WAF is a litle low on that hahaha, so i was thinking of building 1 (big) stereo amp. Maybe two transformers in one case?

 

[dady]

I didn't see before that the ground is floating on the ps.

 

[Chamberman]

Implementing the revision of mr. Pass, would this be the right way to build the PSU if i would want to use 1 transformer for a stereo configuration?

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

You would need 2 X 36VAC or more if you build it this way.

 

[Zoef]

It's getting to technical for me now, i wil stick with the mono's

 

[6L6]

If you are building the amp, you need to understand the technical... At least a little.

We are here to help, please ask whatever you need.

 

[Zoef]

[emoji2]

 

[Zoef]

What i did not get is why the secondaire voltage needs to be higher if i would want to build a stereo amp with just one transformer. And the floating ground. No good?
I made the schematic the way i thought was right, so if there is a fault in it, it's mine.
I get why the voltage needs to be higher in a mono. the constant current draw of the amp. But another 14v higher in a stereo ?

 

[Zen Mod]

to avoid overly excessive (even if small one is always amusing , at least for us ) tale chasing , specify exactly what you want - output power , type of the amp (even if Aleph 3 is in title ) and preferred PSU arrangement

in other words ...... ya ask , and ya shall be given

 

[Zoef]

Well since i started this thread i guess it's going to be a aleph 3[emoji12] [emoji12] [emoji12] [emoji12] [emoji12]

You helped me with choosing the right chokes and transformer for a monoblock. (Very happy [emoji18])
I do not get why the voltage needs to be that much higher when i want to make a stereo version. (Question above)

you are right i should be more direct in asking questions.
I get a lot of tips like :replace for a pot and finetune this or that. (I do apreciate advise like that, i just don't understand it)
I just want a amplifier that is rocksolid, all settings fixed.
No adjusteble bias or whatever.(would not even know how to[emoji15] )
Only service i want to do is change the capacitors every 10 years or so. (And maybe a revision that mr Pass made)
The 30w are fine by me. Would like it if the amp had some mussle in the lower impedance. (Output at 4ohms/ stable amp)
I want to do it ones and i want to do it right / the best way possible.

My fault is that i made the project to big. Building a dac, preamp (p1.7 ) and some aleph 3's. And it will be no surprise, all at the same time.[emoji15]

 

[Zen Mod]

print this one ( attached) in highest size you can , read it and think ...... at least a week ; then go back and ask

Alephs - basically they're all almost the same , everything is in PSU scaling (voltage , power) and multiplying output mosfets

be it stereo or double mono , if you want ,say, 25W/8R/channel amp - basic values are the same - meaning on rail voltage and minimum VA of xformer and uF in cap bank , per channel .

edit : go to FW site , articles ....... and read ; you'll learn drekload of basic stuff

you can also download all user/service manuals of official FW products and learn