Aleph J illustrated build guide

[Zen Mod]

do not remove anything from original amp circuit

now- task for today - learn what are source resistors in Aleph J

I'm thinking about mosfet sources, not JFet sources

tip - -they're biggest resistors on pcb

remember - task is not just to make an amp - fun is greatest when you learn along, as much you can ........ so with time neither ZM nor anyone else can sell ya bollocks

 

[peppennino]

When I wrote "remove internal resistor" I referred to the meter. I intended across mosfet sources, but I haven't the JZen schemathic on hand, I watched the photos and make a mistake

 

[peppennino]

Source res are R28 and R29

 

[Zen Mod]

yes, R29 should work

R28 too, but lets choose R29, it's less moving up and down, in any way possible

 

[peppennino]

I imagine that the only method for knowing the full tilt voltage is empirical
In your PCBs what is the lecture needed for Iq setting across R29?

 

[Zen Mod]

you forgot cap across meter

if you know current for full tilt ( buying new. there usually gave that data) everything is easy

even if you don't know, when you get it - all you need is 1V5 battery and trimpot

voltage across 0R27 is Iq (you want) multiplied with 0R27

say that 1A5 is lowest, 2A is highest

 

[peppennino]

Thanks. Yes, opt MOSFETs are different from the store boards, so Iq is bigger. A cap for stabilizing the meter?
Can I go up to say 1,7/1,8A with Dissipante 4U/400?

 

[Zen Mod]

4U/400 is good for 80W per side

go figure

you drew it good now

 

[peppennino]

Ammeter used in old sportcars and motorcycles like old Smiths and replicas with centered zero seem a good base for customization

Smiths AMPERE Gauge Bianco con REPLICA BIANCO | eBay

This Royal Enfield only needs a ZM logo on it

 

[Zen Mod]

can't use centered - they're 0 at mid position

 

[peppennino]

So, they go below zero only with negative voltage, I suppose... Thanks

 

[Kingsportal]

I want to know if its possible to add subwoofer out to an already complete aleph j. I have open baffle speakers and need the sub for lower punch. If so how would I make it happen?

 

[Zen Mod]

active subwoofer, what else ?

 

[jmpyoung]

You just need an active subwoofer with high level inputs.
Using a Subwoofer in a System with no Subwoofer Output – Upscale Audio

 

[6L6]

^^ Exactly this.

My experience with active subwoofers / plate amps is they work as well or actually better when driven by the high level inputs. It’s just a pass-through to the speakers, the plate amp essentially ‘looks’ at the signal and uses it to run the sub. The amplifier (aleph) and the speakers don’t know it’s there.

 

[northernsky]

Hi all,

I bought few months ago aleph j kits and pcbs on DiYaudio store, but just now finally I got time to start my building.
Concerning the Q1A and Q1B transistors, on the offiicial BOM and on DIYaudio store I read 4 x Linear Systems LSJ74 but in my bags I found 4 lsk170 matched quads. Are these a correct replacement for the original ones or I am confusing them with bags of different projects?

Thank you for answering this very stupid question

renato

 

[Eslheadphone]

Do not use the LSK170's in an Aleph J. It will not end well. They are the wrong polarity. The J74 is the correct part.

 

[Kingsportal]

Hi all,

I bought few months ago aleph j kits and pcbs on DiYaudio store, but just now finally I got time to start my building.
Concerning the Q1A and Q1B transistors, on the offiicial BOM and on DIYaudio store I read 4 x Linear Systems LSJ74 but in my bags I found 4 lsk170 matched quads. Are these a correct replacement for the original ones or I am confusing them with bags of different projects?

Thank you for answering this very stupid question

renato

No they will not work.. Take it from me because I already made this mistake.

 

[northernsky]

Hi all,

I bought few months ago aleph j kits and pcbs on DiYaudio store, but just now finally I got time to start my building.
Concerning the Q1A and Q1B transistors, on the offiicial BOM and on DIYaudio store I read 4 x Linear Systems LSJ74 but in my bags I found 4 lsk170 matched quads. Are these a correct replacement for the original ones or I am confusing them with bags of different projects?

Thank you for answering this very stupid question

renato

Thank you for the answers; now I realized my error. When I bought the kits on January I bought the Aleph J transistor kit but I had to buy separately the 2LSJ74.
But when I ordered these transistors I did not realize I had to choose among different ICs and the store sent me the default choice (LSk170).

Now this error cannot be repeated: the Aleph J transitor kit already includes the 2LSJ74s.


Renato

 

[peppennino]

Me: "I think that for J I'll go for Dual Mono in a single cabinet"
ZM: "Take a Dissipante 4U/400"
Me: "It's too big for my rack"
ZM: "Change rack"

Done
The Infinite Improbability Audio Rack