Amp Talk

[Atomic.Sheep]

Hi guys, Ive been playing for 6 months so I am a big noob when it comes to amps. I've got a lot of questions some of which are a little embarassing.

Here is the first (embarassing) one:

1.) what is a pre-amp?

Btw i've read Randall Smith's document on "how amps work" and I understood most of it so I don't mind detailed and complex answers if this is indeed needed. (contradictory to my lack of knowledge yeh I thought so too, but its true)

Here are the links for it if you've missed this on the Mesa site
http://www.mesaboogie.com/US/Smith/MESA_Class_A_Booklet.pdf
http://www.mesaboogie.com/US/Smith/ClassA-WebVersion.htm

 

[Atomic.Sheep]

Sorry for double posting but I was also wondering what a rack was. I think that these things are related coz isn't a rack made of pre-amps?

 

[tavman]

A preamp is intended to provide additional voltage gain of the signal before it gets passed on to the power amplifier, and tends to "color" your sound a bit more than the main power section (this could be debated).

A rack is simply something to put your equipment in... ie rack mounted effects, or rack mounted head vs on the floor or a head on top of cabinet design..

For example Petrucci's new rig:

The middle part being the rack mounted equipment

 

[screamingdaisy]

Below is a preamp and a power amp (both marked MESA);

The unit on top with all the knobs is the preamp. It boosts the signal from insturment level to line level. It also processes the signal by applying gain and EQ.

The unit on the bottom is the power amp. It boosts the signal from line to speaker level.

When you combine a preamp and a power amp into a single unit, it's called a Head;

And when you combine a head (preamp and power amp) and a speaker(s) into a single unit, it's called a Combo;

 

[zakk615]

very well explained!

 

[Atomic.Sheep]

Yeh thax, that was great, a lot of things are now making sense. Just a quick (I think) question before we move on;
I presume you need both the preamp and the power amps in order to be able to play i.e. have any sound come out of the cabs/speakers? Coz I haven't seen any setups whith just the pre amp for example. (just making sure)


BTW, thanx for the reply in the "post your rig" section screamingdaisy, might give it a shot myself, coz my next guitar will definately have a Floyd Rose and I did find it a bit awkward playing on one coz I was so used to my LP.

 

[screamingdaisy]

Yeh thax, that was great, a lot of things are now making sense. Just a quick (I think) question before we move on;
I presume you need both the preamp and the power amps in order to be able to play i.e. have any sound come out of the cabs/speakers? Coz I haven't seen any setups whith just the pre amp for example. (just making sure)

Yes, you need both.....though you can actually use a distortion pedal as a preamp, but it sounds like ***.

BTW, thanx for the reply in the "post your rig" section screamingdaisy, might give it a shot myself, coz my next guitar will definately have a Floyd Rose and I did find it a bit awkward playing on one coz I was so used to my LP.

No prob.

 

[Atomic.Sheep]

Well my next queation is this;
I am unsure of what rectification is exactly. And hence, why are the recto amps called that? Isn't there any rectification occuring in the F series for example?

 

[NoGlassNoClass]

The rectifier(s) in tube amps convert the high-voltage AC from the mains transformer to DC current (that's what tubes run on.) The rectifier can be either solid state (most modern amps), or tube. The SS rec is more efficient, tighter-sounding, and generally makes for a louder amp. The tube rec (vintage/botique amps and some Mesas, because of its inefficiencies, gives a "saggy" or "spongy" response, imparting a sweetness to the tone that just cant be had any other way.

 

[screamingdaisy]

Well my next queation is this;
I am unsure of what rectification is exactly. And hence, why are the recto amps called that? Isn't there any rectification occuring in the F series for example?

The Dual Rectifier was originally named after it's having dual rectifiers (solid state and tube).

The Single Recto only has a single rectifier (solid state).

The Triple Recto is a play on words, it's technically a dual rectifier.

 

[Atomic.Sheep]

Well that makes sense thanx guys.

My next question is: why are there so many different types of tubes? The pre-amps seem to have the 12AX7s the power amps the 6L6s and EL84s. Is that becasue the 12AX7s are better suited for amlifying the weak signals comming out of the guitars? But I presume that there are transistors that amplify this weak signal before it gets to the 12AX7s?

Also in the power section (power amps) the signal gets amplified in stages right? i.e. first the first pair of say 6L6s does the job, then the second pair right? So is this why the Triple Recto is the most distorted out of the three (single, dual, recto) because I know that distortion occurs in the preamp and the power amps, so my logic says that becasue there are 3 pairs of tubes in the Triple recto the end signal is the most "gainy"?

Does this all sound right?

 

[screamingdaisy]

Well that makes sense thanx guys.

My next question is: why are there so many different types of tubes? The pre-amps seem to have the 12AX7s the power amps the 6L6s and EL84s. Is that becasue the 12AX7s are better suited for amlifying the weak signals comming out of the guitars? But I presume that there are transistors that amplify this weak signal before it gets to the 12AX7s?

Rectifiers (and all Mesa's I believe) have no transistor amplification....they're all tube.

Also in the power section (power amps) the signal gets amplified in stages right? i.e. first the first pair of say 6L6s does the job, then the second pair right? So is this why the Triple Recto is the most distorted out of the three (single, dual, recto) because I know that distortion occurs in the preamp and the power amps, so my logic says that becasue there are 3 pairs of tubes in the Triple recto the end signal is the most "gainy"?

Does this all sound right?

I'm no tech, but I believe they're amplifed by each pair at the same time, and that the output of all three is sent out in parallel (ie, side by side, and not one after another)

Also, the Dual and Triple Rectifiers have the same amount of gain, and it's generally easier to get a more distorted tone out of a Dual than it is a Triple.

 

[Jimmy55]

Hi guys, I have questions about my 3 channel dual rectifier that i just bought off ebay, basically the amp sounds absoloute rubbish and i cant seem to get a decent thick tube sound out of it at all, ive tried dialling in suggested settings but this doesnt make a difference, I ordered 2 new 5U4 rectifier tubes when i got it because the other 2 had shattered in the post when i got it, and the only sound that i get on channels 2 and 3 is a cruddy thin grainey sound.. hard to explain but definately not how it should sound. im a bit of a noob when it comes to this sort of stuff cos i never had a tube amp before, at first i thought it could be something internally that was wrong, cos the 2 recto tubes had shattered inside it in the post, who is to say that something else inside isnt wrong inside, then i thought it could be the 6L6`s have died, then i realised that the 2 rectifier tubes that i bought where different to the ones already in it, the shop ordered me 2 5U4GB tubes which look different to the normal 5U4 tubes, does this make any difference at all? please help me and let me know if you know wat the problem could be, this forum seems really tech, that is why i posted here, thanks very much guys

 

[screamingdaisy]

Hi guys, I have questions about my 3 channel dual rectifier that i just bought off ebay, basically the amp sounds absoloute rubbish and i cant seem to get a decent thick tube sound out of it at all, ive tried dialling in suggested settings but this doesnt make a difference,[/
quote]

How loud did you set the master output at? I find Rectifiers sound like gainy *** when the volume is too low.

 

[Jimmy55]

probably something around the 11 o`clock regions, i think im gonna get it serviced and see wats (if anything at all) wrong with it, i think its the best thing to do seeing as i dont have a fuckin clue about these amps. :?:

 

[Jimmy55]

Oh also i forgot, will it make a difference to the sound if i use an ordinary guitar cable to wire my head and cab, i asked a guy in a guitar shop and he said just use a normal guitar lead, maybe this is the problem, i might go out and buy a speaker cable tomorrow if it makes a difference.

 

[Atomic.Sheep]

I ordered 2 new 5U4 rectifier tubes when i got it because the other 2 had shattered in the post when i got it, and the only sound that i get on channels 2 and 3 is a cruddy thin grainey sound.

So you are currently playing without any 5U4s?

And also how loud DO u need to set the dual recto for the distortion to really kick in, is it within the "you won't go deaf and the neighbours won't call the cops" range? (I tried it out at my local music store and I had temporary hearing "decay" afterwards and it still wasn't getting the full distortion)

 

[Atomic.Sheep]

Oh also i forgot, will it make a difference to the sound if i use an ordinary guitar cable to wire my head and cab, i asked a guy in a guitar shop and he said just use a normal guitar lead, maybe this is the problem, i might go out and buy a speaker cable tomorrow if it makes a difference.

It's not gonna make a mojor difference in fact I'd be surprised if u can actaully hear the difference.

Go here it'll explain what to look for when selecting cables:

http://www.guitarnuts.com/technical/cords/index.php

 

[Jimmy55]

lol, nah, im using the Mesa 5U4GB tubes that the shop ordered for me, along with the 4 6L6 STR 425`s and watever factory supplied preamp tubes are in it, the head is run thru a 4x12 recto cab and im playing an m-1000 deluxe, and for some reason it sounds like ***.

 

[Atomic.Sheep]

Well as I said, the cable will do next to nothing as you will read on that site that I gave you, but it would probably be a good idea to get it serviced (I would), but as my first post suggests, I am new to tube amp business too.