I've had real good luck building this Valco 510-11 circuit. For those who would enjoy retrofitting old and good looking vintage cabinets, this design fits the bill. The sound is fat and stuffed to the brim with harmonics. What one could call a "bedroom" amp.
I would be willing to assist in sourcing the 3 common tubes, transformers, and related components. Total cost will be somewhere around $200+ however this circuit is fairly forgiving and used power transformers, sockets, knobs, & chassis not only make the amp look better, it's cheaper as well.
Uses a 5Y3GT, a 6SL7, & a single 6V6. The last one I built went into a suitcase. The preamp section was biased well below maximum, but acted so hot that with the modd'ed preamp volume when turned up added a vibrato. This design is extremely sensitive, simply hammering the neck plays loud.
In this small venue (Cigar Box Nation) I will be glad to share my schematics & links to the most reputable parts suppliers. This amp will not only fit a small foot print, but will preform well with a standard guitar & will allow you, the tube novice (and experienced builder alike) to enjoy the amp that Jimmy Page used to record Stairway To Heaven with.
Search the web for Valco 510-11 images. The drawing is tilted slightly, that's the one.
If there is some interest, I'll post a couple of pics of what I have, maybe a youtube clip as well.
Rest regards, Doug
Man, this looks super cool! Could be a real fun project sometime soon. I love small amps and this one seems like a very nice little design. I for one would love more photos and some sounds...
If you made a youtube clip I would put it on my site!.....I know a lot of folks would like to try
Here is a clip for a customer of his Valco based 510 modded with a master volume & a 3 position mode switch.
Some technical notes:
Master Volume is a sub'ed out 270K resistor going to pin 5 to ground on the 6V6 final amp tube. Replaced w/ a 1Meg pot. This gives the vibrato-tremolo effect above 75% on either the master or pre volume control. Actually adjustment of the master (when the pre is at 75%) sometimes will increase the speed. Played through a 12" 8 ohm speaker. The bigger the speaker, the better. As you can see, I can't play worth a $@*!. But hammering was around 75% of the hard hit volume. It was loud with a bunch of bass. That's one thing you get with these 40's style amps and the larger 8 pin tubes, fat sound.
Some other additions to the included schematic are:
Pin 3 of the 6SL7 shows a 2.2K resistor paralleled with a 25uf electrolytic 25volt capacitor. This is where you can have some fun finding your own sound. What worked for me is connecting the wiper of a 3 position rotary switch to ground, and then the other 3 positions to pin 3 via the 25uf/25v pair on posit 1, and typically a 330k/22uf @ posit 2, and a 100k/47uf @ posit 3. Try your own combo to see what sounds good to you.
You might want to invest in a resistor decade box and "dial" in the resistor w/ your current choice of Cap jumpered across the decade box.
The power transformer (called "PT" or generically "XMF") I normally is anything that will deliver at least 100Ma at about 700 volts AC+. I will list a link to a $70 XMF that will fit the bill. One of my questionable habits is hoarding old scrapped out test equipment, HiFi chassis available from some hard to find resources, but their on ebay. Be it an old Hammond amp chassis, Admiral, Zenith, whatever. Spec'ing the PT for this design includes the following wires: input voltage; should be 112Vac to 125Vac. The output wires will include 2 red wires- red for a reason. These are the High Voltage wires. normally with a halfway center tap colored with a yellow stripe...which will be connected to ground. Also a set of green wires, perhaps also with a yellow striped 3rd green wire which will also go to ground. This is your 6.3Vac filament wires for the 6SL7 & the 6V6 tube. The 5Y3 rectifier tube takes the yellow wires (pair) which is at 5Vac. Here is a link to an affordable power transformer from a very reputable vendor...http://www.classictone.net/40-18085.html
or this one...http://www.classictone.net/40-18062.html
Click on the "specification" link and review the wires and purpose.
On ebay I have noticed these for cheap....http://www.ebay.com/itm/EICO-Signal-Tracer-Model-147A-/121427563398... what you get is a chassis, Power transformer, sockets, rectifier tube, and an eye tube! (I still need to spend a day working on the eye tube bit).
More soon, some vintage "tombstone" pics and links later tonight. - Doug
The ever important 5 amp Variac.....ebay hopefully no more than $50. Having a set of "mini clips" for use for connecting to wires/leads make easy and safe work on these amp projects. And also most important, a collection of 1 watt resistors....ebay link http://www.ebay.com/itm/500pcs-1W-Metal-Film-Resistor-Assortment-ki...