Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Stuff4bikes on March 30, 2022, 10:17:44 pm

Title: Purpose of the resistors in this layout
Post by: Stuff4bikes on March 30, 2022, 10:17:44 pm
The two 470k resistors between the volume pot and pin 7 of V1?

I have a stout TMB that sounds very nice, will this circuit basically sound the same?
I know this has a master but if it's going to mimic the tmb I will pass.
Title: Re: Purpose of the resistors in this layout
Post by: dwinstonwood on March 30, 2022, 10:28:11 pm
It looks like a voltage divider since one of them is connected to the ground buss and the other to the volume pot output.
Title: Re: Purpose of the resistors in this layout
Post by: tubeswell on March 30, 2022, 10:53:20 pm
Yes - its for a minimum of 50% signal attenuation from V1 output (before volume reduction)
Title: Re: Purpose of the resistors in this layout
Post by: bmccowan on March 31, 2022, 05:51:57 am
And for an opinion on your question about it sounding similar to your Stout TMB; if you are looking to build a different sounding amp, my suggestion would be to stray from EL-84s. They have a signature sound. Tons of options out there. If you describe what you might be looking for, you will get more recommendations than you can shake a soldering iron at.
Title: Re: Purpose of the resistors in this layout
Post by: thetragichero on March 31, 2022, 07:37:48 am
so these two resistors are simulating the dual channel plexis with one of the channel volumes turned down, no?
Title: Re: Purpose of the resistors in this layout
Post by: sluckey on March 31, 2022, 08:00:13 am
Quote from: Stuff4bikes on March 30, 2022, 10:17:44 pm
The two 470k resistors between the volume pot and pin 7 of V1?

I have a stout TMB that sounds very nice, will this circuit basically sound the same?
I know this has a master but if it's going to mimic the tmb I will pass.
The two 470K resistors mimic the two 470K mixing resistors used in a real two channel plexi amp.

This amp will sound very much like the stout TMB. It has the same gain structure. The only difference is this amp puts the TMB TS after the second triode but the Stout TMB puts the TMB TS after the first triode. I doubt you could tell which amp is which in a blind A/B test.