Langevin AM-16 DIY?

[dukasound]

[quote author="jrmintz"]Very cool, Chris and Duka! Do we know what the physical dimensions of the board are?

:guinness: :sam:[/quote]

Thanks
Chris said:
The board measures 1.5 inches by 5.125 inches. Only who know to help me about missing tracing.
Also does anybody knows anything about PSU'
Duka

 

[ytrehalf]

[quote author="dukasound"][quote author="jrmintz"]
Also does anybody knows anything about PSU'
Duka[/quote]

From Langevin documentation:

24 v. DC (with negative grounded). 110 ma when on "high-power," 55 ma on "low."



I could scan the original literature if that would help.

 

[jhaible]

You made me curious about this circuit!

I've put it into PSpice, and it shows very interesting behaviour indeed.

Are these Sowter transformers good copies of the original ones?
(Have you made A/B listening tests already?)

JH.

 

[CJ]

Cool! Duka!
Those look a lot cleaner than my layout.
I will connect the traces for you after work, in a few hours,
Make thos traces that I jave enlarged about .1 to .120 inches. They need to be bigger to handle current and mechanical mounting for the trim pot.
Also, this board is so old school that some of the pads are actually vias. There is a small piece of wire soldered thru them and in to the other side.
You may want to convert those to modern vias if using outside fab shop.

 

[jhaible]

[quote author="jhaible"]You made me curious about this circuit!

I've put it into PSpice, and it shows very interesting behaviour indeed.

JH.[/quote]


http://www.oldcrows.net/~jhaible/am16/

JH.

 

[dukasound]

[/quote]
From Langevin documentation:
24 v. DC (with negative grounded). 110 ma when on "high-power," 55 ma on "low."

I could scan the original literature if that would help.[/quote]

Thanks. I wrote in meantime (thanks for current value)
If you can scan (my new song

jhaible wrote:
You made me curious about this circuit!
I've put it into PSpice, and it shows very interesting behaviour indeed.
JH.
http://www.oldcrows.net/~jhaible/am16/
JH.

How I can see langevin_am16_1.sch. In what program?
I have ExpressSCH but I cant open.
Duka

 

[jhaible]

[quote author="dukasound"]
How I can see langevin_am16_1.sch. In what program?
I have ExpressSCH but I cant open.
Duka[/quote]

You would need PSpice (V8) for this - it's the PSpice Schematics file.

But I have made a screenshot of the schematics, too: That's am16_sch.gif .

am16_out.gif is the waveform at the output (with ideal linear transformer, mind you), which looks like ordinary clipping more or less. But if you look at the signal at various points inside the circuit, like the base current of transistor 1 (am16_ibq1.gif and the zoom picture), very complex stuff is going on.

Asuming the model is right (not entirely sure about that - I might have made some errors of course), my first conclusion is this:

The overall feedback makes the output clipping look quite ordinary. But the odd things that happen at the internal nodes will also show to a _small_ degree at the output. I tried transistors with higher beta (in simulation), and the output level was slightly larger, so the feedback is not _totally_ dominating.

Might or might not be helpful for the quest to explain the unique sound of this amp.

JH.

 

[rafafredd]

what´s the specs are you using to simulate the output transformer? Inductance, etc?

 

[CJ]

OK Duka, that bottom trace goes to the point where it is pointed, it joins the junction of the big resistor, as you probably suspeted.

The trace at the top right goes to the big pad it is pointed at.

The third unknown trace makes a right hand turn, goes inbetween the trim pot adjustment hole and the larger necked down trace pad and heads for that small pad that is to the right of the two small pads that are joined together.
cj

 

[jhaible]

[quote author="rafafredd"]what´s the specs are you using to simulate the output transformer? Inductance, etc?[/quote]

I read about 1+1+1+1:1+1 at the sowter site.
So I modeled 6 equal windings with inductance as a parameter. The simulation is done with 10H for each partial winding, which was only guesswork. (The idea was to choose it so high that it's pretty ideal; even more so as the simulation is at 1kHz.)
I had no hope of simulating the real transformer or its interaction with the active circuit. Just wanted to understand the active circuit in the first place.

JH.

 

[CJ]

don't forget the two large pads for the transistor heat sinks. The heatsinks get pop riveted to the board and there are two large pads on both sides of the board for heat dissapation. If you elect to stand the transistors upright and clip on a heat sink, the base lead will have to come inbetween the c and e leads, since the transistor is flipped.

 

[CJ]

You might want to exten the board a little bit in both directions in order to have enough room for some mounting holes. As it stands, you need the original brackets to slide the board into.
Also, I measured hole diameter for most of the small lead parts as about 0.040 in.
You might want to use 0.060 for the transformer mounting holes. I do not know what size wire Brian uses on the Sowter re-issues.
cj

 

[Moby]

You would need PSpice (V8) for this - it's the PSpice Schematics file.

Yes, it's clear I have the software, could you send me a file? I can help Duka with further experiments :green:

 

[jrmintz]

Thanks for doing all that work, CJ. These are something I've always wanted but never got around to. I will now! Or as soon as I finish the stuff I've already started. Hey, you haven't dissected any transformers lately - no raw material?

Thanks to you too, Duka.

:guinness: :sam: :guinness:

 

[dukasound]

[quote author="cjenrick"]don't forget the two large pads for the transistor heat sinks. The heatsinks get pop riveted to the board and there are two large pads on both sides of the board for heat dissapation. If you elect to stand the transistors upright and clip on a heat sink, the base lead will have to come inbetween the c and e leads, since the transistor is flipped.
[/quote]

Tell me dimension of heatsink.
Is now tracing correct?

I will check hole dimension.

Here is pcb with standard laydown trim pot like this:

Look PM Chris
Duka

 

[jhaible]

[quote author="Moby"]

You would need PSpice (V8) for this - it's the PSpice Schematics file.

Yes, it's clear I have the software, could you send me a file? I can help Duka with further experiments :green:[/quote]

I'm not quite sure which file you mean.
The link I have given, in particular the file
http://www.oldcrows.net/~jhaible/am16/langevin_am16_1.sch
*is* the PSpice file.

The *.gif screenshot which shows the schematics to document the simulated circuit for thouse who don't have the software. If you have the software, just download the *.sch file and run it in PSpice (V8).

JH.

 

[rafafredd]

Duka, the board looks good!

Would there be enought interest so that we can ask Gustav for manufacturing some batches?

 

[dukasound]

Chris,
Check this:

or in pdf file
http://www.cankar.net/duka/AM16_Piher&original.pdf
Duka

 

[asm]

of all the praises ive heard for this thing, i would definately be in for at least 2 boards.

 

[CJ]

see below: