Aleph J for Universal Mounting Spec

[dmtparker]

More is nearly always better.
Measure the output impedance/internal resistance of your battery,

How do you do that? Can I just put a DMM set to ohms across the +/- terminals? Or is there a more complicated way?

10uF film is good on the output

I always thought 'by-pass' caps were a couple orders of magnitude smaller than that - like 0.1uF or even smaller.

 

[Zen Mod]

ohmmeter will go nutz

however , as I'm lazy and 2pico started it , I'll leave to him explanation - how to

(even if I think it's pretty irrelevant practically , if accu is big enough)

 

[Bigun]

Just put 10,000uF per rail good quality electrolytic. I didn't calculate this recommendation but I bet you it's good enough in practice

Not convinced myself that you need any film bypass caps, but I'm not a bypass kind of guy (yet).

 

[2 picoDumbs]

How do you do that? Can I just put a DMM set to ohms across the +/- terminals? Or is there a more complicated way?
I always thought 'by-pass' caps were a couple orders of magnitude smaller than that - like 0.1uF or even smaller.

None of it probably matters if it is a single ended power supply or +/- power supply on balanced amp operating in Class A.

You can just throw a few big caps on it and be done with it.
The point I was trying to make is if the noise level and output impedance is already good adding caps won't bring you any improvement.
You could just add at 10000uF electrolytic and a film cap anywhere between 1uF an 10uf some people go smaller and that's fine too. I usually prefer to sit on the side of overkill.

To measure internal resistance. Measure V across battery with 1 Meg resistor (or just measure V across terminals of battery) , then measure V again with a 20 Ohm resistor (doesn't have to be 20) rated appropriately (maybe 50W), you will see a voltage drop. I assume you are using two separate batterys to make your supply.
Noise might be impossible to measure accurately unless you have an oscilloscope. You could look at mV AC (not dc) you might see something not sure how trust worthy it would be cause you would need an expensive wide bandwidth multimeter.

Best measurement is always your ears, try with and without caps and judge for yourself.

 

[Zen Mod]

and (missing) calculus for Rout is ....... ?

( Rout=ΔU/ΔI )

 

[2 picoDumbs]

Yeah. This time not lazy.
I was in the middle of taking kids to school.

 

[mp3dragon]

hi, can i use mixed irfp240 and 2sk1530? ( ofcourse irfp240's at ccs, 2sk1530's at signal line)

 

[Zen Mod]

you can , but according to fact tat you needed to ask , implies that you're not capable of solving Aleph CCS AC gain puzzle

 

[Bangla H]

Aleph J with IRFP250 M

Hallo Friends.

First Thank is going to Mr. Pass and second to 6L6 for all great illustration build.
I now also can enjoy the Aleph J and understand the different Aleph a bit more
better.
First i have pull out the F4 for refitting with better cooling.
The Fischer Heat Sink allows the J to work with 340mV not to hot day long.
JFet Input are in 10mA range. The IRFP250 M is the modern 5. generation
HexFet with a bit lower Cob- i don't know if it can better anything in sound,
but they work fine and are stronger 30A.
I use a 10k Pot to input also in ACA, Aleph M.
From first start after setup carefully bias point i was impressed by the fullbodied
tonality- somehow a bit like pentode with more Raffinesse.
The clearness and transparency is non fatigue your ears you can follow light the
fluide music presentation- don't know better to tell it.
I have only done two shoots from my build comparing to ACA with R15 mod.
The Amp is closed in Heart- i like, but must wait to colder winter evening now.

Thank you here to ALL have proportion that we can enjoy this Amp.
Now i am waiting for TeaBag M2 GB Boards- another Genius Stroke!

Bangla.

 

[kpsthakur]

There are enough places for pots on the new boards that you could likely use non-BL and it still work very well.

Hi 6L6, can you help with more insight into this please...I have grade A 74's with Idss in range of ~5mA....as Zen has suggested I could parallel them, any way I could use them directly....


TX


Kamal

 

[Zen Mod]

of course you can use 5mA there , though it'll sound little better with JFets not working exactly on 100% of Idss

compare price of JFets with price of original FW amp ;

what is conclusion ?

(then imagine value of this one )

 

[kpsthakur]

Agree Zen, I have ordered all relevant JFET”s at my US address...matched / sorted...for F5/F6/AJ/BA-3, but I in India for now, heading back March next year....man needs to survive on his DIY dose till then .. I just had grade A handy, but the parallel formula is working out for a single channel only...guess I will have to live listening from one ear till then [emoji23], so try to evaluate all opportunities until I am back in states

 

[6L6]

Remember that the Aleph uses a CCS in the input amplifier, it will determine the current more than the Idss will. Use the 5ma if you have them.

 

[kpsthakur]

Got it..[emoji106]

 

[Zen Mod]

in case of that , this is perfect opportunity to test construction with one wimpy pair vs. doubled wimpies

make it with two A per channel , and double them when you can

 

[kpsthakur]

in case of that , this is perfect opportunity to test construction with one wimpy pair vs. doubled wimpies

make it with two A per channel , and double them when you can

Ok, but just want to ensure I don’t end up frying them...hope I keep rest of the values same as the BOM

 

[6L6]

Won't be a problem. You will be able to make a fine amp.

 

[kpsthakur]

Roger that...will share results once done...thank you gentlemen

 

[kpsthakur]

Sorry bothering you folks again, any chance Toshiba-2SJ103-GR could be used instead of 2sj74’s

 

[Zen Mod]

well ....... you must to double or even triple them

xconductance is the reason