Pre-amp section design reading

[caspercody]

Looking at the pre-amp sections of tube amps, it looks like most are the same layout. Is there a easy to understand article of what the components do in each section?

The reason I am asking is I want to try to get more gain out of my Dr Boogie, but not sure where to start.

Why do I want more gain? I just want to learn how to do it, and thought that would be fun to do with this design.

Thanks
Rob

[PRR]

> most are the same layout

Tubes is tubes. While there are many ways to skin cats, only a few work good. And minor variations do not make real changes.

> what the components do

Resistors resist, tubes modulate, caps carry audio.

You want to understand the -whole- stage, and relations between stages.

http://www.freewebs.com/valvewizard/
http://www.tubecad.com/
http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html
http://pentodepress.com/
http://pentodepress.com/home/classic-circuits/fender-champ-5e1-preamp/
http://greygum.net/sbench/sbench101/

> I want to try to get more gain

Guitar amps need GAIN. And low cost. Most classic designs leave little or no gain un-found.

Modern designs alternate gain stages and loss sections to tailor the overdrive tones. "More gain" may be easy, but it may become an uncontrollable hiss/screech/fart monster.

The short answer is to add a stage. The easy answer is to put a booster pedal in front.

[caspercody]

Thanks! I will look at the websites you provided.

Is one of the main differences between say a Bogner and a Boogie the filtering between stages? Like you said a tube is a tube, but they all have a distinct tone. And maybe I am after the wrong thing as far as wanting more gain. I hear bands like Korn that sounds like huge gain, but maybe it is a low tone gain?

[defaced]

The difference between a Bogner and Boogie, or more correctly for an old Dual Recto, an SLO 100, is alot in the details actually.  B+, bias points, coupling cap values, interstate filtering... They're basically the same (SLO/Dual Recto and the Uberschall) when you look at overall architecture (four gain stages and a cathode driven tone stack, long tailed phase inverter and AB1 output stage), but the devil is in the details.  If you want to build high gain amps, read up on how to clone an SLO.  Those guys know their stuff, and the only place online where I've seen people talk about high gain amps like they're easy - which once you know what you're doing, they are.  

This is probably what you're after, and on this very site: http://www.diystompboxes.com/wpress/?page_id=10
Merlin's site is really good (valve wizard) as is Randall Aiken's: http://www.aikenamps.com/TechInfo_2.htm
And more generally, these guys know their crap and there's a TON of back posts to search through to answer your questions: http://music-electronics-forum.com/

[stringsthings]

... "More gain" may be easy, but it may become an uncontrollable hiss/screech/fart monster....

lol 

i've just found the name for my new pedal design !!! 

[caspercody]

Thanks for the info.

I actually want to try to clone a Uberschall, I found a schemtic for the Uber but not sure how accurate.

Does anyone have a schematic for the Ubershall?

[defaced]

Yes, but you have to find it.  Re-read my post carefully.

[caspercody]

If I am getting what you were saying, the Uberschall is a variation of the SLO/Dual?

But it is always nice to have the schematic.

[defaced]

Nope.  Ya missed it. 

[electrosonic]

Lots of good reading in the "tech info" section here.

A.

[electrosonic]

Forgot the link...

http://www.aikenamps.com/

A.

[caspercody]

Clone a SLO?

[defaced]

Follow your nose.  You're on the right track.  

[caspercody]

Think I got it.

Thanks
Rob