Langevin 5116b preamp

[rafafredd]

Yeah, I think cassettes. Not that difficult to work with... have a look on this old thread for a picture:

http://www.groupdiy.com/index.php?topic=8196&highlight=electrodyne

 

[emrr]

Yeah, those are the AM-201-A version. Completely different ballgame in terms of service. There really is no room in the AM-5116-B for anything. The space between board and bottom of module is 7-8 mm and loaded with resistors giving no free space; 22mfd/350 caps are 12-13mm thick. Original caps are a can type mounted to the circuit board. You'd have to pull some resistors, pull the can cap (leads and all mounting points; don't f%ck up the board), then figure out what you want it to look like (re-stuff the original can) when finished. Believe me; pretty much EVERYTHING anyone else built in this vein is far easier to service.

pics on ebay of an AM-5116-B; probably for a very limited time. Scroll down and there's one of the guts.

 

[emrr]

Hey, mine work so no need.

My post is about differences; I ain't scared.

But really, tell me, this particular Langevin, and all those RCA's (be they RCA made or UTC made) have the high resistance windings. So RCA apparently specified the details of the wind to UTC, since UTC's don't measure like this.

None of the other pusses are asking the tough questions.

In short version, what are the aims here?

Tighter coupling and more inductance from finer wire?

I'm getting the idea the higher DCR translates to larger matching losses, but maybe I'm misinterpreting. Got that idea from some commentary about the Edcor DCR's some time back.

Check the open primary RCA output I sent you; not as high but I'm remembering secondary in the 120 ohms range for an official 500.

 

[CJ]

you have simoultaneous eq's when doing xfmr work, turns drop, current goes up, but L drops, unless 80 perm,

c core from arnold

no can get nowdays, custom secret anneal i am talkin to Finkey about, top lam guy in the world.

 

[rafafredd]

rafa's best guy in Brazil could not match up to the cj,

really, it was just like this... :grin: :thumb: to CJ!

Well, the fact is that even the wire they used back then was different. It has more copper and less enamel (or whatever you call it)... You have a very thin wire with lower resistance. So the guys at Langevin transformers wired this special wire in special lams until they have aproximatelly 150R in the primary, with 60H. Yeah, for low impedance mics :shock: . Now with 1:20 ratio, do the math and get a picture of the secondary inductance. So, no, nothing sounds exactly like that today... :?

 

[emrr]

And some RCA stuff in the 1945-1955 range has similar DCR readings; I can't find any other examples of DCR in these ranges.

 

[rafafredd]

strangely, it´s not noisy at all, I mean, in subject listening tests. i´ve used ribbon mics on mine many times, in the hi gain setting. Never actually measured the noise thought, because it never bothered me. And yes, it sounds stupidly good!

 

[emrr]

Noise? Did someone say something about noise? I didn't. Only the academic observation of difference in DC readings from the standard readings.

 

[CJ]

noise?

cmmr, not emmr

ok, perm back then was lower, they had 50/50, but not 80, so as soon as perm went up, turns go down, get it,?
but now saturation, welcome to the transformer jungle. Langevin, who worked for W.E, like C cores.
He was about quality.
C cores are low loss, but expensive to make, a real pain, you have to saw them very slwly, otherwise, the ibration cancels the grain orient, then you have to dip them in muriatic (HCl acid) pool hemicals to remove the abrasive material.
But the effort is worth it.
strip wind a core, so it is in between a torrid and a E
i setup. which has air between the lams, thus the .9 stacking (K) factor associated with EI cores.

that why the guys who buy MCI cosoles rip them out, KC and the Sunshine Band qas recorded thru a MCI with the xfmr's ripped out, thats why the presteine clavachord on Shake Shake Shake,
listen to how clear, no noise, for 1976, pretty good.
------------.

remember, the perm of air is very low, compared to steel, so the less air, the more inductance.
put a c clamp on a utc and check it.

 

[emrr]

Ah, but UTC's, Amertran's, Kenyon's, RCA's, Ferranti's, Thordarson's, etc etc etc from the 1930's all fall in line with the normally-seen resistances (600 ohms at 40-80 ohms DCR) too.

Pretty sure I don't know enough to understand fully, but the difference is still curious.

WE 618B comes in at about 220 ohm on the 600 winding I see.
1947 Langevin 116 (408B / 313A) iron comes in high also.
1947 Langevin 117 iron (408A / 311C) looks more normal.

 

[Marì]

Here's some info from the '61 Langevin catalog that should help to fill in the gaps.

Model AM-5116-B
Power requirements:
Plate: 300VDC
25mA for output power of +24dBM,
12mA for output power of +18dBM (strap removed)
Filament: 6.3V AC or DC at 900mA

Tube check meter: model MTR-506. (No other info given).
Like PRR says, you don't really need this function if you're not running banks of these things.

The B- and the chassis grounds are connected together, all right, but only at one point in the entire system. This is common practice for lowest hum. By way of illustration, here's Langevin's "Recommended Wiring and Grounding Practices" diagram.
Page 1
Page 2

Transformer info:
Input: TF-132-B
Source impedance: 150/600 ohms
Secondary impedance: 60K to push-pull grids
Max level: 0dBM
Electromagnetic shield

Output: TF-129-A
Primary impedance: 20KCT
Secondary impedance: 600/250 ohms
Max level: +26dBM

So, PRR, what became of this old Langevin console of yours? If it was scrapped, I'll cry :roll:

Hi, please one information about 5116 B circuit. I'm trying to understand the circuit: is it balanced trough the grids of tubes? Not transformer balanced? Is it a class A push pull? I cannot understand what tube mic pre nowadays has a similar circuit? I ve seen you have great knowledge about this mic preamp... can you help understand please? Some people say that they are push pull, others that 5116 B are push pull but in class A. What is a push pull in class A ? Transformer balanced or balanced trough the grid ? If you can help me thank you so much!!

 

[emrr]

Yes class A push-pull. There was a discontinued Manley that was class A push-pull.