For your amusement: WE 141-A preamp clone

[emrr]

Here's an example of the Western Electric 141-A preamp circuit I hacked into a recipe box years ago. Wish I had better pics of it. No WE 618-B here; using a 1960's era Gates Radio / Triad input transformer. I went with a pot for fully variable NFB gain control, versus the original (3) 10 dB steps, and added an input pad. Pretty nice high gain circuit that more people should try, given the low parts count and cathode follower output stage.

 

[Viitalahde]

:thumb:

Proper!

 

[rafafredd]

mmm.... Do you have schematics? I have some of those gates input transformers... How does it sound in this circuit?

 

[emrr]

Don't remember; I sold this 5-6 years ago.  Any standard mic to grid input will work.  The lack of output transformer definitely makes the bottom tighter.   Having a NFB based volume control, the tonal color does shift dramatically with adjustment end to end.    

circuit

 

[rafafredd]

wow, that´s an interesting circuit!

 

[b2]

Hi, :grin:

Yes ,it's an interesting schemo but it's seem to be very difficult to find information about the WE 618 transformer that is used in this preamp.did you have some information about it or what kind of transformer ratio could I used
instead of the WE 618?? It's seem to be a high gain preamp 40dB to 70dB,may be nice for ribbon mics :thumb: !

Best Regards,Bruno. :thumb:

 

[emrr]

'Mic to grid' is really all one needs to know. The sec is 30K, which no one makes anymore. Very little difference in practice from either 15K or 50K.

 

[b2]

Hi, :grin:

Thank's for the reply,I was in this idea cause I've got interesting oep transformer from radiospares (x187b)which is done for 600/200 to 47k,so I m building with and in my local old electronics store I've found 4 6j7 ,I've got 12sn7 instead of 6, but.. :thumb:

Good caps+tubes+ glass of red wine and all this gone right :green:


Best regards,Bruno :thumb:

 

[emrr]

Sounds like the right parts pile; have fun!

 

[vintagedreams]

Where dies the wire below R3 in the schematic go? It goes off the top of the page?

Tim

 

[gary o]

Wow , lush thats what I call DIY.....also would love to see the feedback path would like to knock one of these up, thanks for posting.

 

[gary o]

Interesting stuff here

http://www.butterylicious.com/Schematics/Western-Electric.htm

http://www.butterylicious.com/Schematics/Langevin.htm

 

[bluesbaz]

can someone get this schematic back up. Everything online has the top half cut off. 

 

[emrr]

 

[bluesbaz]

Thanks!! I just thought there was some kind of flying lead freak show happening over the top of this circus.
-s

 

[dustbro]

What's going on with pins 7+8 on the 6SN7? Havent seen anything like that before.
Does pin 1 of the 6J7 go to ground?
What's the note on R15?

Your box looks awesome!

 

[bluesbaz]

I would love to know what the comment on r15 says I'm guessing some type of gain setting. As for 7&8 of the 6sn7 thats just some fancy-ass heater artwork. 

 

[emrr]

R15 strap dependent on need (or not) of 600 ohm load capability.

 

[dustbro]

thanks!  Is R15 + R16 620K or 820K? It's hard to tell on the scan.
Is C6 (50uF) electrolytic?
TIA

 

[dustbro]

I wanna give this circuit a try. Can you guys look over my layout for any errors? (sorry, I'm not a P2P guy  :-[)