does mesa use Diode clipping in there amps?

[jamme61]

Is all the distortion and crunch on Mesa's generated using cascading preamp (all tubes) or is some of it using diodes to clip the signal? I know the Marshall Jubilee uses diodes, what about Mesa amps?

 

[ursinus]

That would be blasphemy! Look at the schematics, all tube distortion.....

 

[jamme61]

ok cool, I have looked at the inside of my amp and there seems to be a lot of diodes in there (like the ones in my overdrive pedals) I'm no tech so I wasn't sure. Thanks

 

[parsky1]

Diodes are also used for rectifying an AC voltage (Making it DC). They are also used to allow current to flow only one direction and not allowing it to flow backwards in electronic circuits too. So don't think that just becuase you see diodes that they are used for clipping (ewww).

 

[jamme61]

Yea, like I said I know little about this stuff but, it seemed like a lot of these suckers were on the board, and right where the mode switches go to the board, not by the power supply and they are the little clear glass ones like you see in a stomp box. I was just curious thanks.

 

[AdmiralB]

None of the 2203/2204 amps have diode clipping. The 2205/2210 channel-switchers can - there are two different versions of these amps, the ones prior to 1984 don't have it, the later ones do (although I think the later ones sound better).

The Jubilees and their later JCM 800 cousins have it, as well as the JCM 900 amps. The JCM 2000s do not.

 

[JimAnsell]

i HATED those channel switching jcm 800's.
wow, did they sound horrible.

quiet, lame, bland clean on one channel, then noisey bad distortion on the other. weak reverb, just no good over all.

 

[123thefirst]

I think most modern Mesa amps use a lot of diodes in the channel switching circuitry, mostly for switching the LED's on and off.

 

[AdmiralB]

I think most modern Mesa amps use a lot of diodes in the channel switching circuitry, mostly for switching the LED's on and off.

The LEDs *are* the diodes.

Mesa uses diodes for rectification (and remember the filament supply is also rectified to DC for the relays and V1), and they also have diodes in parallel with the relays for spike suppression.

Some amps (Maverick, Heartbreaker) use diodes in the 'switch mute' circuits too.

 

[jamme61]

The leads that run from little toggle switches (the different mode voicings) run to the board and right there on the board are those little diodes that you see in a overdrive or distortion pedal. I thought maybe these are being used by mesa to give us the different mode voicings? I guess not but it seemed possible. What are they using to create the different mode voices(IE blues, burn, tite, fluid drive, etc.) ? just curious sorry if this is a stupid question or impossible to answer.

 

[123thefirst]

The LEDs *are* the diodes.

Technically, but not functionally...

 

[linuxpng]

That would be blasphemy! Look at the schematics, all tube distortion.....

Does that apply to the rect-o-verb combo amp as well? New to the whole electronics part of amps and never really thought about that before.

 

[trem]

It's funny how people praise the holiest-grail-all-tube-signal-path-jcm-800 cuz it doesnt use clipping diodes only to use a tubescreamer (with clipping diodes) in front of it. That goes for recto users as well.

~trem

 

[msi]

Mesa generally uses varying amounts of gain with selective eq'ing between gain stages to change the tones of their amps. An example would be the Lonestar, the Normal, thick, thicker switch adjusts how the high end of the tone stack behaves. The clean/drive switch adds an additional gain stage. With the exception of the V-twin and some of the bass amps 99% of the distortion in mesa amps are from the tubes. Sometimes in cases such as the triaxis you can overdrive things like the fx loop but mesa did not design that stage for deliberate clipping.

 

[jamme61]

Mesa generally uses varying amounts of gain with selective eq'ing between gain stages to change the tones of their amps. An example would be the Lonestar, the Normal, thick, thicker switch adjusts how the high end of the tone stack behaves. The clean/drive switch adds an additional gain stage. With the exception of the V-twin and some of the bass amps 99% of the distortion in mesa amps are from the tubes. Sometimes in cases such as the triaxis you can overdrive things like the fx loop but mesa did not design that stage for deliberate clipping.

Thanks, on the mode changes, are they using Caps to change EQ? like say a brite cap on a Marshall Plexi? Thanks

 

[msi]

On the Lonestar I believe it's just switching caps in and out. On the three channel dual rectifiers the pushed mode on the clean channel lets more gain through between gain stages.

 

[jamme61]

On the Lonestar I believe it's just switching caps in and out. On the three channel dual rectifiers the pushed mode on the clean channel lets more gain through between gain stages.

I always wanted to mess with the values of those caps, but I would only wind up killing myself and ruining the amp LOL. Thanks