Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Rockranger on April 27, 2020, 11:35:41 am

Title: Stout MV
Post by: Rockranger on April 27, 2020, 11:35:41 am

Hey,
    Just wondering how some of you guys would put a master volume in the Hoffman stout https://el34world.com/Hoffman/files/Hoffman_Stout.pdf . I had a few ideas just wondering the best way to do it.
   Thanks

Title: Re: Stout MV
Post by: shooter on April 27, 2020, 11:48:08 am

can't see the need myself, there's one on the guitar, one on the amp  :dontknow:

here's some ways
http://el34world.com/Forum/index.php?topic=3496.0

Title: Re: Stout MV
Post by: SILVERGUN on April 27, 2020, 11:48:20 am

You "could" just replace R12 with a 500K pot.


I would try a switchable resistor across the OT secondary as a fixed/switched attenuator. Don't forget to switch speaker jacks to match the new load.


Maybe both moves if you cant leave the house right now. The resistor is easy to try without commitment. The pot takes a few more minutes.

Title: Re: Stout MV
Post by: Rockranger on April 27, 2020, 12:00:43 pm

Thanks guys

Title: Re: Stout MV
Post by: Latole on April 27, 2020, 12:02:40 pm

Quote from: shooter on April 27, 2020, 11:48:08 am

can't see the need myself, there's one on the guitar, one on the amp  :dontknow:

A " real" master volume is a complete different thing.
I use this one sometimes :

Title: Re: Stout MV
Post by: sluckey on April 27, 2020, 12:20:13 pm

I recommend this...

Title: Re: Stout MV
Post by: shooter on April 27, 2020, 01:35:35 pm

Quote

A " real" master volume

YUP
and after 5 years reading of folks doing 'em and 70% not liking them or not "getting what they hoped for" I still don't see a purpose, build a low watt amp for low watt conditions, build a big amp for big amp conditions, be happy  :icon_biggrin:

Title: Re: Stout MV
Post by: kagliostro on April 27, 2020, 03:59:35 pm

Give a try to this

(https://i.imgur.com/BDZcfrV.png)

Obviously you must use (instead of R21 - R22) a dual ganged 470K (or 500K) pot instead of the 250K pot of the schematic (and no fixed bias)

--

Here you can find indication to obtain a log pot from a linear one (if you don't find a dual ganged log pot)

http://www.geofex.com/article_folders/potsecrets/potscret.htm (http://www.geofex.com/article_folders/potsecrets/potscret.htm)

elsewere you can give a try also using a linear one

Franco

Title: Re: Stout MV
Post by: PRR on April 27, 2020, 08:06:06 pm

Or this. Take the "820r" resistor bigger and bigger to taste.

Typo: it either should be REVerse Audio taper, CW for "LOUD"; or Audio taper marked "Choke" and turned the other way. (Tack-in any handy pot and try at 10, 5 and 0.)

The other problem is that EL84 is SOOO sensitive that it is really hard to turn drive down enough to reduce the racket.

Title: Re: Stout MV
Post by: kagliostro on April 28, 2020, 06:15:11 am

Egnater on the Rebel 20 uses both triks at the same time, Pot on PI cathode + PPIMV

(https://i.imgur.com/vzwslNx.jpg)

https://el34world.com/charts/Schematics/files/Egnater/REBEL20sch_8-09_with_Values.pdf (https://el34world.com/charts/Schematics/files/Egnater/REBEL20sch_8-09_with_Values.pdf)

Franco