Langevin AM-16 DIY?

[CJ]

OOOps!
I lifted the pot and to my chargrin, noticed a couple of mistakes. Should have lifted it
a long time ago, but here ya go.
sorry!
also, you need to make the middle hole for the pot the same dia. as
the other two.
also, silkscreen needs inductor labeled. L1 or whatever the schematic
says.
cj

 

[Kev]

It is always worth digging a little deeper.

So cj ... how is it all going ?
I think there is enough raw data now.

 

[CJ]

well, Duka is doing all the hard work. After he updates the files, I will attempt
a doublesided etch so I can make sure the darn thing actually works before anybody rushes off to the fab shop.
But if you want to start a page, go for it. Call it Kev's AM 16 since you will be doing all the work.
We need a source for the two big transistors, maybe a more modern package as you suggested. And that little inductor has to be sourced also. After that, it's a piece o cake!

And maybe somebody more familiar with routing software could come up with a single sided version from the schematic for those who want to etch their own board....but I am going for the full retro version. Those boards are so small, you could get an 8 channel pre inside one box.

 

[Bear]

Yeah, I was thinking about whether it's practical to poach ideas from the original for more conventional and available iron. I guess the DC issue is the biggee, and I don't know what iron would cope.

Bear

 

[CJ]

The transformers have to be balanced perfectly. The coils have to be wound a certain way, otherwise, you can get instability. There are many coils inside those darn things. They all have to be phased correctly. There are a lot of wires coming out of those transformers, which makes it expensive to build. The transformers are probably 80 percent of the sound, rather than, say the transistor types used. I tried a 7903 on the input and it did not get that sound. Too sterile. Remember, there are some ties between Western Electric and Langevin, so you might think of those transformers actually being Western Electric, which is probably the highest priced transformers on ebay.
I have never seen Langevin AM 16 transformers on ebay.
But I did just see a guy who wants a thousand bucks for two rusty AM 16's!

 

[CJ]

Duka, the heat sink pads are about 0.34 in. diameter.

I forgot all about Gerry's site:

http://www.geocities.com/ciminosound/langevin-am-16.html

Did Ciminosound turn into somebody else?
:wink:

 

[alk509]

Yeah, what happened to Ciminosound? There's almost no Lab members in New England left!

Peace,
Al.

 

[maxwall]

PCB size ?

 

[CJ]

1.5 in by 5.1 in.

Hopefully, somebody will lay some parts down and do an auto routing board-single sided. I don't want to screw with the sound possibly being tweaked, so thus the original.
cj

 

[MikoKensington]

What about Sowter's Iron? We could make a request from Prodigy Pro.

 

[dukasound]

[quote author="cjenrick"]OOOps!
I lifted the pot and to my chargrin, noticed a couple of mistakes. Should have lifted it
a long time ago, but here ya go.
sorry!
also, you need to make the middle hole for the pot the same dia. as
the other two.
also, silkscreen needs inductor labeled. L1 or whatever the schematic
says.
cj
Hi Chris
I make both pcb for Piher trimpot and like original.
Original is like this. Also, on silkscreen is L1:

For original I havent raster for trimpot but with comparation with pcb pics I find this.
Look both:
http://www.cankar.net/duka/AM16_Piher&original.pdf
Duka

 

[dukasound]

Any ideas about Gain control.
I mean it would be usable.
Thanks.
Duka

 

[dukasound]

[quote author="cjenrick"]Duka, the heat sink pads are about 0.34 in. diameter[/quote]

I put about 12mm diameter space without contacting trace. Maybe some insulator would not be bad between heatsink and pcb.
Duka

 

[ciminosound]

Did Ciminosound turn into somebody else?

No I'm in the middle of a "friendly divorce" if there is such a thing. The computer has been at the house and I've only had "weekend visitation rights" :roll:

I just got cable at my new place so I'm pulling the computer over there this
weekend. I'll be around a lot more soon.

Lot's going on, new studio, new workshop, finding boxes of cool stuff in the old shop. I even found a box with some AM16 trays for when I get around to building my own. I forgot I had them!!!

:sam:

 

[Gus]

Duka there is no easy way to make a gain control for this circuit.

It is an elegant and limited circuit almost everything interacts for bias points and gain can't change one without effecting another.

 

[Winston OBoogie]

...

 

[soundguy]

you really dont need a gain control on these things, I use these on EVERY session I do, and they are very happy to feed an 1176 or something like that for gain control. the smart thing to do would be adding attenuators, but I just plug mine in to 1176's and all is well.

I wonder how close the sowter transformers are going to sound to the originals to really tweak on doing a double sided layout to preserve the original sound. Guess you gotta try to know though!

dave

 

[dukasound]

[quote author="Gus"]Duka there is no easy way to make a gain control for this circuit.

It is an elegant and limited circuit almost everything interacts for bias points and gain can't change one without effecting another.[/quote]

Hi Gus
I am not for changing circuit. I mean like pad on input (5,10,15,20db)

 

[CJ]

Looks great Duka! Ther eis still on mistake, the trace going past the trim pot needs to go to the two pads that are touching, to the left of the single pad where the trace is now.
The trim pot hole in the middle measures about 0.160 in. The two holes for the trim pot tabs measure about 0.100 in.
The two 0.100 holes are about 0.630 apart from each other.
cj

 

[maxwall]

DIY land

Does any one have the dimensions of the AM16 board - length x width ?

would be nice to get this info since I do not have an original myself.