Langevin Attenuator "A" - Audio or Linear?

[Phrazemaster]

Hi all, I ran across an old listing for some Langevin attenuators and some were labeled "Curve A" and some "Curve B."

I understand normally A pots are logarithmic (I had learned "Audio is A"), but I also know the letters A and B were not always consistent; sometimes B meant Log and A mean linear.

Can anyone confirm that Langevin attenuator A curve attenuators use log laws?

Thanks,

Mike

PS not sure where this post belonged...

 

[Phrazemaster]

Wow 60 views and no replies...I thought for sure someone would know.

If anyone knows I'd appreciate it. I found some cool old Langevins but don't want to buy them if they are audio taper...they are labeled curve "A".

Thanks for any insights...

Mike

 

[abbey road d enfer]

What do you want to use them for?

https://www.technicalaudio.com/pdf/Langevin/Langevin_Attenuators_list_1967.pdf

 

[Phrazemaster]

What do you want to use them for?

https://www.technicalaudio.com/pdf/Langevin/Langevin_Attenuators_list_1967.pdf

They are for a UA 176 build. Input/output attenuators are supposed to be linear on this unit.

By inference from your link - that RAT types are linear, it would seem the one in question is an Audio taper as its code RMXD-201. So must be audio taper.

Many thanks Abbey!

Thanks for the link!

Mike

 

[emrr]

A 176 uses 2db/step attenuators, no?  They’re in db/step, whatever.  That’s not really a ‘taper’, being stepped. 

The Langevin rotary types are sealed, can’t be cleaned, and if you take one apart (they don’t go back together), not very well made, not compared to Daven, etc.  I’d say out of 30ish or so I’ve had and examined, 1/3rd had problems.  I’d never recommend one unless it was fully vetted first. 

 

[abbey road d enfer]

They are for a UA 176 build. Input/output attenuators are supposed to be linear on this unit.

In the manual, both input and output attenuators are described as "0 to -40dB in 2dB steps.
In the 177, the attenuators are quite different, since they are just 500 ohm rheostats, and probably linear taper.

 

[Phrazemaster]

A 176 uses 2db/step attenuators, no?  They’re in db/step, whatever.  That’s not really a ‘taper’, being stepped. 

The Langevin rotary types are sealed, can’t be cleaned, and if you take one apart (they don’t go back together), not very well made, not compared to Daven, etc.  I’d say out of 30ish or so I’ve had and examined, 1/3rd had problems.  I’d never recommend one unless it was fully vetted first.

Thanks so much for your wisdom and experience. Totally helps!!! I appreciate knowing Davens are more reliable too!

 

[Phrazemaster]

In the manual, both input and output attenuators are described as "0 to -40dB in 2dB steps.
In the 177, the attenuators are quite different, since they are just 500 ohm rheostats, and probably linear taper.

Thank-you Abbey; super helpful!

 

[Greebok]

Thank-you Abbey; super helpful!

Hey Mike, your PM box is full, I cannot send you a message..

 

[Phrazemaster]

Sorry email me directly: webjammer at earthlink dot net

Thx,

Mike