Aleph J Schematic

[Zen Mod]

> even 27 can be fine ;

You probably have not been listening to Mr. Curl on the Blowtorch thread.

Whether the JFET will blow at 27V is one thing, whether it still operates properly is another.


Patrick

EUVL , gimme a break ;
if it works on 24 , it will work even on 27 ...... but you must always count on +10% in mains voltage . that is where is real danger , not in squible about tiny fraction of lesser performance;

if I must pay price as usual to collect knowledge in mentioned thread... that always leave bad taste in my mouth .

man can resort on L input filter if xformer in case is on high side , voltage wise .

or burn few volts in R part of CRC filter
whatever

if you wanna comment something - ask Papa why he isn't cascoded little critters

 

[EUVL]

> gimme a break ;

I gave you a hint.
Please feel free to decide whether to do anything with it.




Patrick

 

[B.L.]

My Aleph J - modified A5 PCB.

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

 

[traw]

Repeat of question is post 127. Any notable difference taking the usual 'fine tune dc bias' adjust resistor (68k) after the two resistors to base rather than from in between the two resistors (1.5 & 3.32)?

 

[hifimaker]

My Aleph J - modified A5 PCB.

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

This type of horizontal layout is really nice.

One thought, could the distance between the 2 output sections of MOSFETs be increased to better take advantage of the heatsink? Having the actual dimensions of this board would be helpful to judge.

Having space for the 2 additional output MOSFETs is a nice option for higher biased version.

In both board designs above it's great to see the input and output sections on one board rather than 3.

Just my $.02 worth.

Nice work guys.

-David

 

[GRollins]

I must say that I'm not a big fan of running semiconductors at their rated limits, much less over.

Grey

 

[Zen Mod]

I must say that I'm not a big fan of running semiconductors at their rated limits, much less over.

Grey

me too .......... but that was not a question .........


that's same as using gas toob at max current .

looking in devils eye

 

[hifimaker]

Wouldn't the additional mosfet's spread the load across more parts? I'd like to bias the amp to produce full power into 4 ohms rather than 8.

-David

 

[B.L.]

Isn't distance between output sections enough?

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

 

[Ryssen]

I have some pcb´s for babelfish they are 22cm long and have C/C 5 cm between the fets.5 cm seems allright.
How long is your bord?
And where to find a schema for A5?
Hope you do some series making of those boards later..

 

[jacco vermeulen]

output sections enough?

Not enough for 100 watts, imso.

 

[steenoe]

Cleaned up a bit, we're slowly getting towards something useful:

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

Bottom layer pdf: http://www.hb001.de/aj_pcb3.pdf

Really nice work, Mr Barske

 

[steenoe]

I must say that I'm not a big fan of running semiconductors at their rated limits, much less over.

Grey

Me too!! Not mentioning; recommending it to the average DIY'er

 

[Holger Barske]

Thank you very much, Steen. Here's the latest version:

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

Doubled the power resistors, so 1R/2W types can be used (much easier and cheaper to get over here), added two decoupling capacitors, increased the space between the output transistors, and did some other minor modifications. Pcb is now 100 * 100mm. If anyone's interested - here's the bottom layer pdf: http://www.hb001.de/aleph_j5.pdf

 

[jacco vermeulen]

Starting to look like a tolle biene, Holger.

 

[jupiterjune]

ask Papa why he isn't cascoded little critters

I am curious about that too.

I had my blue aleph mini boards cascodeded briefly, and listening in mono I noticed the detail was amazing. But it went POOF the next time I turned it on, and the jumper wiring I did to cascode it was too much of a PITA to swap out the jfets, so I didn't keep the cascode.

But I am working on a cascoded aleph board -- with the intention of becoming a respectable citizen by doing away with the blue boards in my mini-a.

JJ

 

[carpenter]

...unless the blue boards are the product of Peter Daniel...

 

[EUVL]

> Not mentioning; recommending it to the average DIY'er

Right on.

And I was trying to point out that even the device would survive the breakdown voltage, it would have so much leakage that it would no longer behave as it should.

Not that everyone cares to know ......


Patrick

 

[Ryssen]

Not that everyone cares to know ......

I do!

 

[MRupp]

Here's the latest version:

Here's the latest version:

I know this is really nitpicking but for R5 / R6 you could use 2 resistors in parallel instead of series connected ?