adding "Squish" to a tube amp

[Kane17]

Re: adding "Squish" to a tube amp

ok, So I borrowed a variac from a friend..about to try it out but I'm a little hesitant.

I did a google and there's not much said about the dangers...one site said "The jury is out wether this damages the amp or not" and thats about all I could find.


So, anything I need to know before I fire this thing up?

 

[Kane17]

Re: adding "Squish" to a tube amp

Well if anyone is still following this, I tried out the variac down to about 105 volts, I really dont know how harmful it is to the amp so I'm still hesitant to go lower.

Pretty subtle but definately noticeable that the breakup came quicker and was softer. Played at half volume mainly. Typicaly in that range I would get just a buzzy grit in the highs during pick attack and then just mildly compressed tone. Also if tubes clipped it would not be pleasant since it was getting loud at that point.

At 105v the breakup was more balanced from picking until tone rings out. I could make music and the breakup didn't clash when I used my DS-1 but rather complimented it. I was getting a much more "stringy" tone, slightly EVH-ish but I think my heavey toned guitar was keeping from nailing it.

The whole sound is something new to me, a little out of my playing style. Still, it helps me to understand and appreciate what this amp is aimed at. I think it would sound much better with a tele or a strat rather than my dean ML /w DD bridge.


Are there any variacs built with the guitar amp in mind? Or something with a tighter voltage range?

It would be so easy to accidentally bump the one I have here and push the voltage way out of range...I know this cuz I did that when we had it hooked up to some wire to do some cutting. One careless moment and I bumped the voltage so high that the wire exploded. I could have lost an eye....heck I could have lost a friggin' leg!


I think I might try changing the preamp tube and see how that goes. I probably will get a variac if I find one cheap since it definately opens up some big potential here.

I dont see any good prices on variacs. It is definatly hard to justify spending more on a variac than what the amp is even worth just to gain a few more tonal options....

 

[Kane17]

Re: adding "Squish" to a tube amp

slightly OT, has anyone used variacs with solid state amps? I'm curious how it would affect my marshal but I'm even more hesitant to try that on my own...I hear that if you breathe wrong at your ss marshall your reverb dies and then one by one your knobs stop responding.

 

[Majestic]

Re: adding "Squish" to a tube amp

EVH used his VariAC at much lower than 105. It was more like 85 or 90, if I recall correctly.

If I'm not full of sh*t......and I'm admittedly no electrician......you're basically working your power tubes very, very hard at that level, but WITHOUT jacking-up the voltage. You'll probably strain your transformer, be it Megatron, Optimus Prime, or Starscream, and likely burn through power tubes at a quickened pace, but I'm not really competent on whether or not you'll actually "damage" your amplifier.

I'm leaning towards "No". Again, I'm not an electrician or an amp electronics guru. If anything, use my message as a genesis for inquiry.

I'm just surprised you're not using one of the newer methods, like an Air Brake, etc.

 

[rashayritto]

Re: adding "Squish" to a tube amp

i've seen many youtube vids of people using weber attenuators with their valve jr's to get really sweet "weeping" tone. Might be what youre looking for as the amp sounds like a sore throat screaming when its cranked (at least with my livewire metal)

 

[TheArchitect]

Re: adding "Squish" to a tube amp

I'm trying to get what I want out of my Epiphone Valve Jr.


When I just use on overdrive pedal like my tubulator or sd-1 I get a good strong and solid overdrive sound but using my DS-1 is a little harsh..

That sounds like every DS-1 I have ever heard. I think the problem is in the pedal, not the amp. I play my Vjr stock for a while before heavily modding it. Its a cool little amp.

 

[missionamps]

Re: adding "Squish" to a tube amp

Well if anyone is still following this, I tried out the variac down to about 105 volts, I really dont know how harmful it is to the amp so I'm still hesitant to go lower.
....

It won't hurt the amp to run it at lower and lower primary voltages.
There will be no transformer damage and for all practical purposes, there will be very very little cathode poisoning, which I'm sure somebody is waiting to jump in with.
You'll get down to a point where the filament voltage will be so low that the tubes will not heat up enough to conduct properly.
Remember, vacuum tube amps are thermionic... which means the tube's cathode has to be boiling hot in order to emit many electrons out to the plates.
I can't remember 100% on these amps but I the reissue LP jr. uses a solid state full wave bridge recitifer block and I think these do too.
You can lift the grounded anode ends of the FWB and insert a resistor between it and ground to simulate a "tubey" rectifier sag.
The anode lug is the one marked ' - ' and is grounded.
But as mentioned previously, a single ended class A amp doesn't swing current like a class AB so the "sag" won't be as dramatic... it will lower the voltage to the amp, similar to what your variac is doing but only on the DC side.
Check this site out and see if anything suits your fancy:
http://duhvoodooman.com/VJr/VJr_mods.htm

 

[louthunder]

Re: adding "Squish" to a tube amp

Having a tube rect. is important for that "squish" sound, but so are the power tubes. I'll bet that the Airline amp has 6V6 power tubes. In the right circuit 6V6 tubes give exactly the sound your descibing.