Langevin AM16 on my bench!!!

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dukasound

Well-known member
Joined
Jun 4, 2004
Messages
711
Location
Kotor, Montenegro
Hi Langevinians :sam:
Langevin is on my bench :grin:
DSC07824b.JPG

After about three months I received AM16 :grin:
I resoldered a couple of wires and IT WORKS. All parts are original. Transistor Q1-Q6 are 2N5210 and I suppose Q7 and Q8 are 2N3053. Both input and output transformers I connected to 600ohm. Now I use «Low Power»..
On PSU I saw 24,3VDC. Checked voltages who is higher than in manual (maybe with «High Power» will be lower).
Voltages.gif

Then I adjusted balance. Because I havent distortion meter I check with simple method. I adjust trimmer for zero voltage beetween emiters of Q5 and Q6.
DSC07836b.JPG

DSC07837b.JPG

DSC07839b.JPG

A little crash on AM16 face :sad:
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Also I make and chech a Joe' input pad. It works very good.
DSC07851b.JPG

Variable_20dB_PAD.gif

Sound is nice and FAT. I compare AM16 and my dbx286A (bypass compressor,etc) and it sounds much better.
Thanks to my best man Mickey from Chicago who bought this for me and Joe for suggestions about input pad and other dilemmas.
Duka
 
Congratulations, Duka! I bought a pair of these a few years ago. I really like the sound. Very thick with a smooth, mellow top end.
Regards,
Scott
 
[quote author="scott_humphrey"]Congratulations, Duka! I bought a pair of these a few years ago. I really like the sound. Very thick with a smooth, mellow top end.
Regards,
Scott[/quote]
Thanks Scott
Did you checked voltages and do you have some input pad?
Duka
 
[quote author="dukasound"]Thanks Scott
Did you checked voltages and do you have some input pad?
Duka[/quote]

I built a fixed pad (~ -20 dB) that I can switch in and out. I like the way you and Joe did it, though.

I don't have a distortion meter, either, so I had to adjust based on voltages like the manual said. As I recall the voltages were fine and I didn't have to adjust anything. I did put some attenuators at the output.

langevin_front_controls.jpg


langevin_open_top.jpg
 
I have DIY circuit boards for the AM16 , send me a email if your interested.
 
Hey Scott

Very nice box. I love those red knobs. Who make them?
Where can I buy some?

chrissugar
 
[quote author="chrissugar"]Hey Scott

Very nice box. I love those red knobs. Who make them?
Where can I buy some?

chrissugar[/quote]

They're Daka Ware knobs. I bought them from http://www.leedselect.com/parts-knobs.html. I just ordered the last two, though. Sorry. The guy that I talked to at Leeds Electronics said that they used to have hundreds, but apparently these went fast. You might try checking eBay.
 
maxwall, there was another thread where you can find at least pdfs for etching.
http://www.groupdiy.com/index.php?topic=2672&postdays=0&postorder=asc&highlight=langevin+am16&start=0
CJ finished some and was pretty satisfied with the result. He also used the Sowter trannies.
The input attenuator is probably imedance-matched to the Zin of the input tranny, an output pad should be impedance-matched to the Zout of this trannie. In this case you can maybe use the same pad for in- and out, depending on how the trannies are soldered. But you should have a inputpad for preventing the input from overloading .
Jens
 
[quote author="dukasound"]Nice pots Scott :thumb: . What kind :?:
How did you fix AM16 on chassis?
I measured voltages with High Power
Voltages2.gif

Duka[/quote]

I used Daven attenuators (model # laq-350-g). The are 600ohm/600ohm attenuators.

I used the high voltage configuation, too. I used to have an original manual for these, but unfortunately I moved recently and the literature I have is packed in a box somewhere in my garage.
 
[quote author="dukasound"]
How did you fix AM16 on chassis?

Duka[/quote]

I used silicon sealer, the stuff that you can by at automotive stores. I was careful not to let the chassis of the AM16 contact the rack chassis (to keep the ground loops away).
 
[quote author="matthias"]@ scott:

that looks really professional !!

how did you do the panel labeling ??
is that somthing like a printed clear foil or a real print...??

mat[/quote]

Thanks, Mat!

The labels are from my deskjet printer. I bought some silver, metallic stickers and printed onto them, then I coated them with spray lacquer. It's not very durable, however, but it's good enough for light use in the studio rack. Future projects will be done with front panel express.
 
[quote author="Rob Flinn"]

Just a small point but if you have these mic amps set for +24dBm operation the harmonic generation is greater by 0.25% than if you have them set for +18dBm. Check page 4 of the spec sheet.[/quote]

Thanks for the info! Here's a link to the manual for anyone else who's interested:

http://www.geocities.com/ciminosound/langevin-am-16.html
 
hey Scott,
nice looking rack up.
I love mine, but my metalwork is so much better now, I'm thinking about a rerack, maybe add a few more bells and whistles as I do so.

What are those caps i see hanging off the connector?
a litle psu bypass/stabilasition?

Nice pics
Sleeper
 
Remember the AM16 output must be loaded by 600ohms to keep the frequency response flat. If you do not load the output you will have a 1 to 3dB rise by 20kHz which rises to about 6 to 8dB at around 40khz. Doesn't sound much but in listening term it is the difference between warm or harsh.

Also if you are running into pro level recording A/D systems which take +18dBM to +24dBM to clip using an output pad will stop the output from actually reaching these levels without the AM16 clipping. So really all that is needed is a variable input PAD. To change the 20dB PAD shown on the previous page to a variable 45dB PAD change the 150ohm resistor to 10ohm.

Joe

www.jlmaudio.com
 
[quote author="JLM Audio"]Remember the AM16 output must be loaded by 600ohms to keep the frequency response flat. If you do not load the output you will have a 1 to 3dB rise by 20kHz which rises to about 6 to 8dB at around 40khz. Doesn't sound much but in listening term it is the difference between warm or harsh.

Also if you are running into pro level recording A/D systems which take +18dBM to +24dBM to clip using an output pad will stop the output from actually reaching these levels without the AM16 clipping. So really all that is needed is a variable input PAD. To change the 20dB PAD shown on the previous page to a variable 45dB PAD change the 150ohm resistor to 10ohm.

Joe

www.jlmaudio.com[/quote]

Great info, Joe. Thanks.
 

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