Hoffman Blues Jr conversion "Meat" circuit

[Goldpeak]

I don't seem to get much change in tone using the meat control. Mainly just a little fuller sound, but barely perceptible. Has anyone experimented with a different resistor for R27? Thanks in advance!

[Willabe]

What value are you using?

And schematic please.

[acheld]

Always good to upload a schematic with your question -- saves folks from finding one.   I'm uploading the standard version, but maybe you have made some changes??  Or not.

Of course this part of the circuit provides variable amounts of negative feedback.  It is designed for an 8ohm speaker -- other impedance taps will give different responses.   

I've built a couple of these, and was not overwhelmed by the "Meat" pot effect.     

Edited:

I had to change the values of both the pot and R27 to find a range that worked for me.  I can't recall where I ended up.

[Willabe]

....I'd also suggest substantially decreasing the pot value.

No, lowering the value of the meat 1M pot will lessen the effect. The 1M is there to totally stop any NFB.

Disconnect  R27, that will give you the most "meat" effect you can get, that's all there is. That disconnects the NFB.

[Goldpeak]

Always good to upload a schematic with your question -- saves folks from finding one.   I'm uploading the standard version, but maybe you have made some changes??  Or not.

Of course this part of the circuit provides variable amounts of negative feedback.  It is designed for an 8ohm speaker -- other impedance taps will give different responses.   

I've built a couple of these, and was not overwhelmed by the "Meat" pot effect.   By decreasing R27 you will see less negative feedback, and increase distortion -- I assume this is what you want.   I'd also suggest substantially decreasing the pot value.   One place to start is by trying R27 at 22k.  Play the amp -- louder is better for this effect -- and when you find sound you like, measure the total resistance across the pot and resistor together.  That will give you range to aim for.

Also recall that the pot is an audio taper (eg, log plot), and is not linear.  So you will hear the most change at the lower endif the pot rotation.

[Goldpeak]

What value are you using?

And schematic please.

 

[acheld]

Apologies for my earlier mis-statement on wiring the "Meat" pot.

Gross generalization:  The more NFB signal you allow to hit the signal path, the less distortion you will get, and the more clean headroom.    So, if you're looking for more distortion, the higher resistance will be your friend.

It normally takes some experimentation to find the sweet spot for any particular amp.

[Goldpeak]

Apologies for my earlier mis-statement on wiring the "Meat" pot.

Gross generalization:  The more NFB signal you allow to hit the signal path, the less distortion you will get, and the more clean headroom.    So, if you're looking for more distortion, the higher resistance will be your friend.

It normally takes some experimentation to find the sweet spot for any particular amp.

Thanks very much.

[Goldpeak]

Always good to upload a schematic with your question -- saves folks from finding one.   I'm uploading the standard version, but maybe you have made some changes??  Or not.

Of course this part of the circuit provides variable amounts of negative feedback.  It is designed for an 8ohm speaker -- other impedance taps will give different responses.   

I've built a couple of these, and was not overwhelmed by the "Meat" pot effect.     

Edited:

I had to change the values of both the pot and R27 to find a range that worked for me.  I can't recall where I ended up.

What grit or drive I get is volume @ 3 & master upwards of half way. Fat switch applied. 

[Willabe]

I don't seem to get much change in tone using the meat control. Mainly just a little fuller sound, but barely perceptible.

Disconnect  R27, that will give you the most "meat" effect you can get, that's all there is. That disconnects the NFB.

[stratomaster]

If you just want it to do more than it's currently doing then decreasing R27 to say 33k will give you much more NFB at the minimum pot setting.  This will thin out the sound a good bit, so I don't know how useful that is to you.  But it'll definitely give that knob more to do.

[tubeswell]

If you want to install an NFB ‘on/offswitch’, make it short R21 to ground.