18 watt TMB MV

dcburn

dcburn

Well-known member
Guys,
Is there anything I can do to make the taper on my MV actually useable?
Just like a Fender HotRod, 0-1 on the MV and it is screaming!
Attenuator needed, sounds good with one.

Built amp with a 1 meg Alpha pot.
 

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Try the Friedman 220k resistor (or there abouts) coming off of the master pot.

Copied from another user on here,

“The MV uses a 220k resistor in series with the master volum wiper after the tonestack so u don't lose bass at low vokumes.. you gain bottom and bass at the expense of volume loss, but the volume is much more than the 1.2v P-P needed intomthe power section tomdrive it to full volume, so no real loss and benefit at low volume. Its an old MOD n covered in Kevin O'Connor's books.”
 
Chubbs said:
Try the Friedman 220k resistor (or there abouts) coming off of the master pot.

Copied from another user on here,

“The MV uses a 220k resistor in series with the master volum wiper after the tonestack so u don't lose bass at low vokumes.. you gain bottom and bass at the expense of volume loss, but the volume is much more than the 1.2v P-P needed intomthe power section tomdrive it to full volume, so no real loss and benefit at low volume. Its an old MOD n covered in Kevin O'Connor's books.”
Click to expand...
Thank you!
Ill check that out.
 
Chubbs said:
Try the Friedman 220k resistor (or there abouts) coming off of the master pot.

Copied from another user on here,

“The MV uses a 220k resistor in series with the master volum wiper after the tonestack so u don't lose bass at low vokumes.. you gain bottom and bass at the expense of volume loss, but the volume is much more than the 1.2v P-P needed intomthe power section tomdrive it to full volume, so no real loss and benefit at low volume. Its an old MOD n covered in Kevin O'Connor's books.”
Click to expand...

I’ve done something similar to this with an 18 watter and it worked really well.
I think I got the idea from a ceriatone c-wreck layout

IMG_5630.jpeg
 
Last edited:
@PLX

Not sure I have figured out what is funny, or what you laughed at?
I actually figured you would be one to comment with experience and some advice seeing that you build?
 
dcburn said:
It doesnt matter that my cap values on the board arent the same?
Or do end up changing out some caps there as well?

Im looking at the dual 250 pot with the two 2M2 resistors?
Click to expand...
the cap values won't effect adding these resistors. I would certainly keep them as they are. The resistors I mentioned are just a simple attenuation circuit that will send a small portion of the signal to ground so that it is not hitting the power amp as hard.
From the schematic you posted, this would be similar circuit to your TMB channel where there is a 470k resistor between the channel volume and the v2 tube, with the 500k channel volume pot acting as the 2nd resistor to ground
 
dcburn said:
Guys,
Is there anything I can do to make the taper on my MV actually useable?
Just like a Fender HotRod, 0-1 on the MV and it is screaming!
Attenuator needed, sounds good with one.

Built amp with a 1 meg Alpha pot.
Click to expand...
Sounds like you used an “audio” taper 1meg alpha pot.
Simple fix would be to buy an “linear” taper pot and wire in the way you have it.
Problem solved more than likely.
 
gtrwun said:
Sounds like you used an “audio” taper 1meg alpha pot.
Simple fix would be to buy an “linear” taper pot and wire in the way you have it.
Problem solved more than likely.
Click to expand...

You've got that backwards.
His description reads as if he has a linear taper pot currently installed. If so, try an audio taper.
 
So went on Valvestorm and it looks like my kit came with an audio taper pot.
Wondering if I installed in the wrong spot? It also came with a 1 meg linear taper as well...
 
dcburn said:
So went on Valvestorm and it looks like my kit came with an audio taper pot.
Wondering if I installed in the wrong spot? It also came with a 1 meg linear taper as well...
Click to expand...
The 1 Meg linear is most likely the bass control pot.
An audio taper pot is the correct one to use for a master volume as it will be more gradual than a linear, but depending on your preference it still may not be gradual enough on its own
 
Aynirar27 said:
The 1 Meg linear is most likely the bass control pot.
An audio taper pot is the correct one to use for a master volume as it will be more gradual than a linear, but depending on your preference it still may not be gradual enough on its own
Click to expand...
You're right!
As long as I got the correct parts, from the schematic, I mixed up my bass and MV pots.

Should I change the bass to linear while I have chassis out of headshell?
 
dcburn said:
You're right!
As long as I got the correct parts, from the schematic, I mixed up my bass and MV pots.

Should I change the bass to linear while I have chassis out of headshell?
Click to expand...

Its up to you if you want change the bass pot. using the audio taper pot there certainly won’t hurt anything, and if you like the way it sounds by all means leave it in. But the audio pot will affect the curve of your eq slightly compared to the more “classic” linear pot
 
Aynirar27 said:
Its up to you if you want change the bass pot. using the audio taper pot there certainly won’t hurt anything, and if you like the way it sounds by all means leave it in. But the audio pot will affect the curve of your eq slightly compared to the more “classic” linear pot
Click to expand...
Im just being lazy.
When I get chassis out, it wont take much more to change out a second pot.
Just got to work up some ambition!
 
dcburn said:
Im just being lazy.
When I get chassis out, it wont take much more to change out a second pot.
Just got to work up some ambition!
Click to expand...
This thread is working up my own ambition. The last build I did I tried to squeeze into a single week that I was on vacation and it didn’t go well lol.
I think it’s time to get back on the horse
 
dcburn said:
Im just being lazy.
When I get chassis out, it wont take much more to change out a second pot.
Just got to work up some ambition!
Click to expand...


I'd say install the correct pots as long as the schematic is correct for the circuit. That said, an audio taper pot would be what I'd likely consider for a MV.
 
I actually ordered another Alpha 1meg audio taper pot.
Schematic calls for 1meg linear bass and audio MV, but both seem to act as linear (?).

I built the amp a year or so ago, but I remember not knowing which 1meg was which?
IIRC I never found a marking between the two that was different?
 
dcburn said:
I actually ordered another Alpha 1meg audio taper pot.
Schematic calls for 1meg linear bass and audio MV, but both seem to act as linear (?).

I built the amp a year or so ago, but I remember not knowing which 1meg was which?
IIRC I never found a marking between the two that was different?
Click to expand...

If there is no marking (or, even if there is ....), it's easy to check with meter. Not sure if you've tried that yet.
 
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