Plexi Amps

[johnny blackwater]

Re: Plexi Amps

The variac is not used to reduce the output volume like a hotplate, supposedly Eddie used the variac to reduce the input voltage to 90 volts, then the amp was REBIASED at the lower voltage, changing the character of the power tube responce. if the amp were to then be plugged into a standard wall socket at 123 volts, the tubes would probably red-plate. if you think his amp was not modified, ask Mark Cameron about that.

 

[TheArchitect]

Re: Plexi Amps

The variac is not used to reduce the output volume like a hotplate, supposedly Eddie used the variac to reduce the input voltage to 90 volts, then the amp was REBIASED at the lower voltage, changing the character of the power tube responce. if the amp were to then be plugged into a standard wall socket at 123 volts, the tubes would probably red-plate. if you think his amp was not modified, ask Mark Cameron about that.

I don't know or care who anyone is. I do know that adjusting the bias is a maintenance item not a modification. It gets(at least should be) fine tuned to match every set of new power tubes that get installed.

 

[Dr.Mavashi]

Re: Plexi Amps

The only Plexi tone with high gain and typa' playing that I am into is this:
http://www.georgelynch.com/rigs/liverigs/backfortour.html
But is really a "watered down" plexi rig ..... oh well my two cents.

 

[MattPete]

Re: Plexi Amps

Plexis are very basic, dry sounding amps. They don't have distortion that peels paint off walls.

VH1, VH2, Vh3, and Fair Warning don't peel the paint off the walls?

but remember even Hendrix, Beck and Clapton used som etype of pedal to push the amp over the top.

You don't need a pedal to push a Plexi over the top -- just crank it. If volume is an issue, try an attenuator, power scaling, or even a post phase-inverter master volume (sounds better than an attenuator, IMO).

Be ready to pay BIG bucks for a Plexi, (20, 50 or 100 watts),

There were no 20-watt Plexis: only 50 and 100 watts.

if you want a'vintage' type of tone then they are worth it, Metal guys from the '70s-90s did not use Plexis with some exceptions VH, being one, but his was not stock) they used the metal face Marshalls with a pedal/preamp, to push the amp ovr the top.

A helluva lot of guys used Plexis, VH, Schenker, ZZ Top, etc.

 

[MattPete]

Re: Plexi Amps

VH, MODIFIED his amp by putting in a variac, thus making his NOT original

VH didn't put anything in his Plexis, and no, the Variac isn't the mysterious magic that get's the VH tone.

It's really ****ed simpled (despite all of the misinformation over the years): plug guitar (preferably with lower output humbucker) into Plexi treble channel and crank into a set of G12m25 Greenbacks.

VH's tone is a stock Plexi cranked into Greenbacks.

 

[MattPete]

Re: Plexi Amps

Here's a really nice clip of a Metropoulos plexi clone. No attenuators, no variacs, no pedals, just a stock amp going into some custom Weber speakers.

http://www.soundclick.com/bands/songInfo.cfm?bandID=662365&songID=5122822

 

[Mr. B]

Re: Plexi Amps

Eddie could have plugged his guitar into an unmodified kitchen toaster, and run that into a bedpan he had picked up at the retirement home for an amp, and he would still sound better than most of us. :fing2:

 

[LooseCannon]

Re: Plexi Amps

Trilogy you're really making a fool out of yourself, if you don't know what's a variac just shut up.

 

[Rich_T]

Re: Plexi Amps

Oh yeah, it not installed?
Tell me where I can buy a variac that "plugs" into an amp.

Can you do this, YES OR NO?!

If you don't think altering the AC flow changes tone on an amp, then you ought to go back to drawing those pretty little houses (w/ smoke coming out of the chimney) and let musicians carry on this discussion.

Here is the point --->.
Here is you ---------------------------------------------------------------------->.

The amplifier components were supposedly unmodified inside VH's plexi. The power flow is this:

Wall socket > Variac > amplifier.

If I were to plug the amplifier straight into the wall, it would be just another plexi. The variac is a seperate device. No one is saying that it does not alter the tone, just that it is not a modification made to the amplifier itself.

 

[johnny blackwater]

Re: Plexi Amps

I don't know or care who anyone is. I do know that adjusting the bias is a maintenance item not a modification. It gets(at least should be) fine tuned to match every set of new power tubes that get installed.

I build and repair amplifiers, its obvious that all you do is play them, If you don`t know what you are talking about you should not advertise your ignorance! Using a variac is an external method of lowering the B+ voltage available to the power tubes (plate voltage) the same thing can be done with internal modifications (dropping resistors) so using a variac is technically a "mod" it is just done from the outside of the amp. With a drop in B+ voltage, the tubes would be biased too "cold" so the bias pot would have to be turned "up" (increase resistance) to achieve the usual 70% plate dissipation. if you then plugged the amp up to the standard 120 Volt wall current, the B+ voltage would increase, changing the Bias, and increasing the dissipation to way over 70%, running the power tubes to hot, and burning them up quickly. Mark Cameron worked on Eddie`s amp, and made a list of the internal modifications done to it, which is posted on the web in several places. Live Eddie used his single Plexi head as a pre-amp, into a load device, then into his effects, and then into a solid state power amp, and then into his 4 x 12 cabinets.

 

[Majestic]

Re: Plexi Amps

Here's a really nice clip of a Metropoulos plexi clone. No attenuators, no variacs, no pedals, just a stock amp going into some custom Weber speakers.

http://www.soundclick.com/bands/songInfo.cfm?bandID=662365&songID=5122822

That sounded really great!

Somebody had another link a couple months ago from a "Funny Money Band" or something like that, and the guy was just playing Van Halen licks with a Pearly Gates through his Plexi, if I recall correctly. That was a great clip as well.