Aleph J Schematic

[buzzforb]

Look on the fourm about ACS explanation. Altering R27 changes the the acs gain/modulation and with it, contribution of upper fet to output. Nelson decided on his values for a reason and I would imagine it is better overall performance. I have read that performance at 1w can be improved slightly, but at the expense of performance at higher power levels.

 

[schultzsch]

in the future I wish to listen to the amp without R27(pure class a) in the circuit but the bias on my side is already high(1.6A/fet and 60C on the sink measured last summer) and I don`t want to get everything on fire
How high the bias/fet gets in the original circuit without R27?

 

[buzzforb]

THE bias of the current source is .65V divided by the Rs of the top fet. If you cut modulation component, then you have a SE amp driving a CCS load. With 1.6a, you better have beefy sinks. The original was bout 1.2A(.66/.47)

 

[schultzsch]

I don`t understand, 1.2a with or without R27 in the circuit?

 

[schultzsch]

ups i did it again
for pure class a I have to remove R24
I remember now that i read somewhere here that also without R27 the sound gets better

confused you a little bit..sorry

 

[buzzforb]

Here is basic schematic. If you want to have just SE amp with CS, you dont need R24, r27, r20-23, and c3. These are the componenents that turn it into a modulated current source, where the signal affects the response of the current source and its contribution to the output.

 

[schultzsch]

so the trick it`s that I have to remove all those components to achieve pure class a, not only R24...ok now I get it
you cleared a little bit the things for me, thank you!

 

[buzzforb]

Look at Zen V2 article on Firstwatt site. The second part of the article he sets up a SE amp with a CCS load. He follows that article up with ZV4, where he introduces the ACS. THe AJ just adds a LTP too the front end and creates nice feedback point as well as ability to drive with balanced signal.

 

[ticktock]

A journey started a long time ago...
hope to finish it soon

Happy New Year to all!!

Happy New Year !!!

Looks nice !!

 

[schultzsch]

thanks!

another day of work..

 

[schultzsch]

tomorrow I want to drill some venting holes in the top and bottom pannels but I have a little problem...as always )
does the size of the holes matter? I thought at 2 options
- single row of holes with relative big hole diameter(10mm will suffice ?)
- 2-3 rows of holes with 3-4mm hole diameter
in which of the cases the convection would act at maximum?
the first row of holes will be at 20mm distance from the heatsink

 

[PKI]

and what are dimensions of the heatsinks?

 

[schultzsch]

300mm l 165mm h

 

[6L6]

I would choose the larger holes. Less drilling required, and (my opinion) better aesthetics.

 

[PKI]

I would choose the larger holes. Less drilling required, and (my opinion) better aesthetics.

And you can make adjustments not taking off the hood

 

[schultzsch]

 

[6L6]

I think he means that you may be able to get an adjustment screwdriver on the adjustment pots (if you include any) through the ventilation holes.

 

[schultzsch]

yes...so the kids would adjust it when i`m not at home

hard decision.. will wait few days so all the components arrive and I`ll see after

thanks for the tips

 

[buzzforb]

My kids have gotten used to open amps laying around. It causes them to ask questions like ,what is electricity. I love it. Amps are looking great. 6L6 is resident perfectionist. Check out his awesome build threads.

 

[PKI]

I will try to make a thread about my Aleph 60 monoblocks building this weekend. It is hard to add something after 6L6's F5 build description, but maybe it will be useful .