Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: wolfiesays on May 04, 2020, 03:11:08 pm

Title: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: wolfiesays on May 04, 2020, 03:11:08 pm

Hello,

First post here! Decided to tackle a quarantine build for an amp based on what tubenit and dageezer contributed. I was going to put an active fx, but ran out of space.

I noticed this has a fixed nfb and no presence control. I wanted to tap in and add a presence control but really do not know how to implement it here. Is this a typical Fender "presence" or will I use a Marshall or TW style? I have an extra hole on my faceplate lol. This is my first build but have done a bunch of research and went with the attached setup for board layout, see pics. I am using geezer's original layout with a 47R not the 60R resistor.

So to get a useable "presence" pot and resistor value what should I go with? and where should I tap into the "tail" of the phase inverter?
I want to run 4 8ohm speakers series/parallel at 8ohms, I will be using a multitap 60W hammond 1650N OT, if this affects the resistors in the nfb (not sure), I am also using a 1971 sup rev PT, non super linear which I assume is 330-0-330.

Go easy on me guys haha.

-wolfie

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: tubenit on May 05, 2020, 06:01:36 am

I think this should work fine for you.  I use this on one of my amps.

With respect, Tubenit

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: Latole on May 05, 2020, 08:16:55 am

Tubenit I have this presence control in one of my amps, a Lifco 1000. First time I see this.
It work great, sound is beautiful.
They call it High Range expender
Pot is a 25k L capacitor is a 0.12 mfd and resistor is a 4.7 k

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: sluckey on May 05, 2020, 11:19:13 am

Quote from: Latole on May 05, 2020, 08:16:55 am

Tubenit I have this presence control in one of my amps, a Lifco 1000. First time I see this.
It work great, sound is beautiful.
They call it High Range expender
Pot is a 25k L capacitor is a 0.12 mfd and resistor is a 4.7 k

That's the same as the Marshall JCM-800 2204 amp...

     https://el34world.com/charts/Schematics/files/Marshall/Marshall_jcm800_2204_lead_series.pdf

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: PRR on May 05, 2020, 12:05:19 pm

>> I have this presence control
> That's the same as...

And really no different from Fender 5F6a presence except without DC in the pot wiper.

How "beautiful" it works may depend also on the speaker and player.

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: 2deaf on May 05, 2020, 12:24:58 pm

Quote from: Latole on May 05, 2020, 08:16:55 am

Tubenit I have this presence control in one of my amps, a Lifco 1000. First time I see this.
It work great, sound is beautiful.
They call it High Range expender
Pot is a 25k L capacitor is a 0.12 mfd and resistor is a 4.7 k

Pete called it a High Range Expander on amps like the Bass Master.  It bears a striking resemblance to Fender's 6G6 Bassman.

Title: Re: Tweed Tweedy BluesMeister BluezMeister presence control
Post by: wolfiesays on May 06, 2020, 01:01:06 pm

Quote from: tubenit on May 05, 2020, 06:01:36 am

I think this should work fine for you.  I use this on one of my amps.

With respect, Tubenit

Thank you Tubenit, this looks great. I will experiment with different values if needed but will start with what you provided.

I will make sure to wire it up the way you put it here too. I like the simplicity of it.

Thank you!

wolfie