Two amp questions for you, Watts and Stages

[SGSlidedawg]

I have two quick questions for y'all..

1. What determines amp wattage, i.e., 50 watts, 100 watts? I was told it has to do with the transformer. Is this true?


2. When an amp builder says he's building an amp with 3 stages. What does this mean? I read in the latest Vintage guitar magizine that this guy is building amps with three stages. What does this do to the over all output tone? Any advantages? Also, are there schematics out there on this?

Thanks!!

SGSlidedawg

[Bob-I]

1. What determines amp wattage, i.e., 50 watts, 100 watts? I was told it has to do with the transformer. Is this true?

That's one of the many factors. Assuming you're talking about tube amps, the type of tube, the way it's biased, the voltage, the xformer etc all affect the output power.

2. When an amp builder says he's building an amp with 3 stages. What does this mean? I read in the latest Vintage guitar magizine that this guy is building amps with three stages. What does this do to the over all output tone? Any advantages? Also, are there schematics out there on this?

I have to make the assumtion you're talking about gain stages.

An amp needs to increase the input signal to a level that the power amp section can take over as the guitar's signal is far too low to run into a power amp. Looking at a basic Fender amp, typically a single triode gain stage will give enough gain to the signal to push the power amp.

There are many other things that are done, one it tone controls which take away gain, so another gain stage is added, typically called tone stack recovery.

Additional gain stages may be used for a number of reasons, reverb recovery is one, and overdrive is another.

With that background, a typical amp like a Fender Champ, will have 2 gain stages, the initial gain stage and the tone stack recovery. Go to an amp that overdrives you add another stage for 3 total gain stages. Some folks like a 4th gain stage which tends to smooth out the overdrive.

I hope that helps.

[Structo]

Also a typical 12ax7 dual triode tube has two triodes in it that can become two gain stages.
Two tubes can be 4 gain stages.

[SGSlidedawg]

Thanks for your help!! I'm trying to understand this with out going out and purchasing 1000 books..

So then the Fender Twin 57' has

(4) 12AX7WA preamp(?) tubes

(2) 6L6 Tonestack(?) tubes

(2) 5U4 rectifier tubes

Does this then mean it's a 8 stage amp (4- 12AX7AW's) or an amp that has 8 gain stages or are the terms one and the same?

http://fender.com/support/amp_schematic ... matics.pdf


Thanks again!!

SGSD

[Structo]

I think that is a reissue, but no not all stages are gain stages.

They can use each half of a tube for different purposes like cathode followers, plate loaded tone stacks, phase inverters, reverb drivers, etc.

It just depends on the amp and what they are trying to achieve with the tubes.

Marshall amps are a good example of gain stages.

You should buy Dave Hunters book, Understanding Tube Amplifiers and Getting Great Sounds
He walks you through the different parts of a tube amp and explains it in easy to understand terms.

http://www.amazon.com/Guitar-Amplifier- ... 087930863X

Sheesh!

I just checked the price of that book. It must be out of print because I think I paid around $25 for it a couple years ago.
You might have to do a little searching to find a better price.

[FYL]

I just checked the price of that book. It must be out of print because I think I paid around $25 for it a couple years ago.

It's still listed as available at Backbeat Books (it's publisher) and may be ordered on line.

http://www.backbeatbooks.com/feature/vi ... mId=331349

[SGSlidedawg]

I think that is a reissue, but no not all stages are gain stages.

Yea you're right Structo, this is a re-issue.

Hey, thanks so much for you're help!! I just ordered the book. Are there other books and/or DVD's you recommend also?? I'd like to make an amp as a hobby. I understand the schematics in a sense of where connection points and such are, I just don't understand the logic behind why or what they're doing. For my first project, I'd like to keep it simple and make a Fender 63' reverb tank for my Bassmann LTD. Then who know's what's next. I have all the woodworking equip. necessary to build the cabinet. In addition, I've done some mods on a couple amps I currently own. I've now gained an interest to build one,,, hook, line and sinker... Ugh!! It's all good...

Thanks and be kewl!

SGSD

[tubeswell]

FWIW Ch 1 of the Jack Darr Book (old fashioned and '60's themed tho' it is) also explains stages in an easy-to-understand sort of way. (There was a site called something like pacificrecone.com that had the first 8 Chapters of the book on it for free but I couldn't find it when I googled just now.)

[SGSlidedawg]

FWIW Ch 1 of the Jack Darr Book (old fashioned and '60's themed tho' it is) also explains stages in an easy-to-understand sort of way. (There was a site called something like pacificrecone.com that had the first 8 Chapters of the book on it for free but I couldn't find it when I googled just now.)

I was able to find it:

http://www.diyguitarist.com/Misc/J_Darr.htm

Thanks!

[M Fowler]

SGSlidedawg,

The Fender type reverb kit is at this site notice there is also a layout there towards the bottom of the page.

http://triodeelectronics.com/diy-fender ... b-k15.html



Mark

[Structo]

real deal

http://www.schematicheaven.com/fenderam ... _schem.pdf

[jaysg]

So then the Fender Twin 57' has...

You managed to pick one the odder configurations out there. Mind, there's nothing wrong with it, but it the Vol1 and Vol2 inputs use one more tube than you would expect and it gets weirder on down the line. The preamp is 2 stage, despite using 3 tubes for 6 triodes. Negative feedback is pulled in at a gain stage, so I would call the gain+concertina part of the power amp, not the pre-amp.

You did find the right forum for your questions. The Trainwreck Express and Liverpool amps are 3 stage, and the Dumble ODS is 4 stage when the overdrive is kicked in. It is 2 stage in the clean mode.

[SGSlidedawg]

opps...

[SGSlidedawg]

So then the Fender Twin 57' has...

but it the Vol1 and Vol2 inputs use one more tube than you would expect and it gets weirder on down the line. The preamp is 2 stage, despite using 3 tubes for 6 triodes. Negative feedback is pulled in at a gain stage, so I would call the gain+concertina part of the power amp, not the pre-amp.

I wonder why Fender would choose to use a 12AX7WA (V1) for Vols 1&2? I find it really interesting when comparing (schematics) how each manufacture is different from another.

Someday, I'd like to try to build a Dumble ODS 124 just for the fun of it.. One of my goals.

Again, thanks for your help!

Ed

[jaysg]

I wonder why Fender would choose to use a 12AX7WA (V1) for Vols 1&2? I find it really interesting when comparing (schematics) how each manufacture is different from another.

I believe the reason is that they're idiots. They know full well that V1, V2, and V3 are supposed to be 12ay7s and that Eric Clapton is the number one reason people are interested in that model. They have all the data on his 3 amps, but choose to ignore it.