Solo boost

[Luthierwnc]

It isn't a tube solution but have a look at an old-fashioned treble booster. I built one recently using the schematic for the Treble Blaster:

http://fuzzcentral.ssguitar.com/rangemaster.php

I added a treble bleed on mine near the output (.01/50k I think) to take the ice-pick off the high end. You could probably work out a tube version of this but I used an NPN NOS Germanium transistor from Small Bear. Except for the enclosure, stomper and transistor, all the other parts are pennies. I made the PCB with crude Sharpie traces -- really simple

Drop one of these boards into the chassis like a Dumble FET with either a panel or relay switch. You could also preset trimmers or put the pots on the panel. Not much real estate in either case. I think this will come close to the sound you are looking for.

Good luck,

Skip

[Andy Le Blanc]

back in the day electro harmonics marketed these little booster things that looked real similar..... a double or triple a battery and a transistor
used to stack them for fuzz\boost....

[El_Martin]

Hi!

I have used the cascode stage (two triodes) of the AX84 firefly in front of Fender type preamps. Works great. Depending on the volumes it is not too compressed. Sounds a bit like pentode input stage. Wtch the maximum heater to cathode voltages...see http://ampgarage.com/forum/viewtopic.ph ... ht=cascode

If youre looking for a more tubescreamer-like saturaded boost, try the Torres Tonefrenzy booster. IIRC its a single stage triode booster w. local feedback in front of the preamp.

Ciao
Martin

[tsl602000]

Thanks for the suggestions, but I don't want an external boost pedal for this amp.
On the Hoffman website is a schematic for a simple gain boost that I'll use.
http://www.el34world.com/projects/image ... LTAGES.gif

[benoit]

Thanks for the suggestions, but I don't want an external boost pedal for this amp.
On the Hoffman website is a schematic for a simple gain boost that I'll use.
http://www.el34world.com/projects/image ... LTAGES.gif

If the thing is going to be footswitchable anyway and you're guaranteed a box attatched by cable to the amp, where's the harm in a pedal, provided it gives the sound/function desired? Not trying to be antagonistic, just asking.

[Luthierwnc]

That layout is for an entire amp. He does have a pedal stomp-box in one of the other projects using 2 12AX7's and a backwards flatpak transformer. I have used the same power source for a Dumbleator and another preamp tube gizmo and it works great.

Whatever you do, if you are using a tube, be sure you don't change the phasing at the input grid. You could get a pop that will wake them in the back of the bar.

Skip

[tsl602000]

If the thing is going to be footswitchable anyway and you're guaranteed a box attatched by cable to the amp, where's the harm in a pedal, provided it gives the sound/function desired? Not trying to be antagonistic, just asking.

This amp is for a friend of mine. He just wants everything in the amp. Personally I use a pedal to boost the pre-amp. He doesn't want that.

I'm still pondering on the volume/clean boost. The amp features a PPIMV and a tube FX loop which is pretty much a dumbleator. Suggestions how to implement that volume boost in this amp are highly appreciated....

[tsl602000]

That layout is for an entire amp. He does have a pedal stomp-box in one of the other projects using 2 12AX7's and a backwards flatpak transformer. I have used the same power source for a Dumbleator and another preamp tube gizmo and it works great.

Whatever you do, if you are using a tube, be sure you don't change the phasing at the input grid. You could get a pop that will wake them in the back of the bar.

Skip

Skip, if I implement this gain boost function exactly like the schematic (I have a triode left in this amp), that wouldn't change the phasing, would it?
Sorry for any dumb questions.. I'm still learning.

[Luthierwnc]

Each triode reverses the phase if the signal goes in on the grid and comes out the plate. If you use a cathode follower, the phase stays the same. Some people orient the speaker polarity to reflect the phasing in the amp. Matchless has a switch to do this. That is a whole discussion you can find here on the amp garage.

In your case, you want to ground the unused triode. Here is a schematic that shows how to do it:

http://www.lynx.bc.ca/~jc/marshallAmps.html

Keep in mind this is a buttload of gain. That's why I lean towards the SS solution. You are going to get a boost above parity on the active loop so running an extra hot stage into the front end might make it pretty unstable.

You might also have a look at the Fender 5E8-A. That is where by selecting jacks you can run two first stages in parallel. You would get some boost without changing the phase or overdriving.

Post your schematic as it gets further along.

Skip

[Luthierwnc]

Each triode reverses the phase if the signal goes in on the grid and comes out the plate. If you use a cathode follower, the phase stays the same. Some people orient the speaker polarity to reflect the phasing in the amp. Matchless has a switch to do this. That is a whole discussion you can find here on the amp garage.

In your case, you want to ground the unused triode. Here is a schematic that shows how to do it:

http://www.lynx.bc.ca/~jc/marshallAmps.html

Keep in mind this is a buttload of gain. That's why I lean towards the SS solution. You are going to get a boost above parity on the active loop so running an extra hot stage into the front end might make it pretty unstable.

Take a look at the Fender 5E8-A low power Twin. On that amp, you can either run a regular input gain stage or two stages in parallel. No phasing issues and you'll definately get a boost.

Skip

[tsl602000]

Skip,
Thanks for the learning experience. I think I better stick to the SS solution.

I've been thinking about a volume boost option (I know that's completely different form the gain boost we were discussing before). MES@ has this boost option in the FX loop. I'm using a built in Dumbleator in my amps with 250KA pots for send and Return. Would a 250KA pot with a relays do to get a usable boost?

thanks,
Coen

[Luthierwnc]

I'm sure it will work. I'm not sure it is easier than working the volume knob on the guitar. No matter where I am on stage, I know where I can find it

[tsl602000]

I know. I never use a volume boost either. But my friend definately wants one....