NAD: Guitar amp using single valve ... now with video ...

4114Effects

Always wanted to make one of these. It's a guitar amp using a single valve - the very cooly named compactron 6AF11. It's essentially an amp in a bottle - 2 triodes and a pentode output stage. Uses a groovy 12-pin base.

These are a little tricky to get right, having all the gain stages in one small valve, but I think I've nailed this one. The outcome was a real surprise, breaks up very smoothly and has a really nice crunch. Not much clean headroom to speak of, but plays very nicely with a guitar volume control.

It's not loud - 2w at max, but it sounds (and looks) amazing. I'm particularly pleased with how the ventilation/viewing hole turned

 I've built 4 more dinky enclosures the same so I might churn some out. 

Pics for your delight...

robinbowes

Those plates are fantastic - the front name plate and rear "spec" plate. Do you make them yourself? Do you take orders? I could do with a custom faceplate for a modified Bandmaster.

R.

4114Effects

robinbowes said:

Those plates are fantastic - the front name plate and rear "spec" plate. Do you make them yourself? Do you take orders? I could do with a custom faceplate for a modified Bandmaster.

R.

My "real" job is as a graphic designer at a printing firm, so I design and print them myself

robinbowes

4114Effects said:

robinbowes said:

Those plates are fantastic - the front name plate and rear "spec" plate. Do you make them yourself? Do you take orders? I could do with a custom faceplate for a modified Bandmaster.

R.

My "real" job is as a graphic designer at a printing firm, so I design and print them myself

Aaaaahhhhh - it all makes sense now!

I'll PM you.

R.

kreggs

Love your ideas. Looks great

bob21

That is super cute! Looks awesome.
What ballpark is the sound in? 

4114Effects

bob21 said:

That is super cute! Looks awesome.
What ballpark is the sound in? 

Hmm hard to describe. Maybe, mini-champ, but with smoother breakup and less rasp/fuzz. Definitely a blues/crunch amp with vintage tones. A lot of fun to play.

Jimbro66

What a brilliant little amp. Is that a rear-mounted 2" speaker?

4114Effects

Jimbro66 said:

What a brilliant little amp. Is that a rear-mounted 2" speaker?

Haha, no - just a vent and viewing hole for the valve

bob21

4114Effects said:

bob21 said:

That is super cute! Looks awesome.
What ballpark is the sound in? 

Hmm hard to describe. Maybe, mini-champ, but with smoother breakup and less rasp/fuzz. Definitely a blues/crunch amp with vintage tones. A lot of fun to play.

Damn. Sounds great! Would love to hear it if you do some clips!

Lebarque

Clips or it didn't happen!

ecc83

Superb! There should be sheds of other, more common valves peeps can try. ECL80, ECL82,ECL83,ECL86 in accending order of power output and in some cases triode gain.

You can probably find the "TV" version with a P prefix very cheaply. Same characteristics but a 150mA heater current and therefore odd heater voltages. PITA to used years ago but with modern 78 and other regulators, easy-peasey.

Ooops! 300mA heaters.

Dave.

ecc83

Missed one! The PCL85. Pretty kick'ass like an EL84 but was used as the field output valve in tellies. Not low distortion I wouldn't think so ideal for geetars!  Cheap too.

Dave.

equalsql

That looks fantastic. What a great idea.

frown

That is awesome! Gotta look into these.

prlgmnr

What's the smallest plausible speaker you could use to make a couple of tiny 4x(whatever) cabs?

4114Effects

prlgmnr said:

What's the smallest plausible speaker you could use to make a couple of tiny 4x(whatever) cabs?

The smallest production guitar speaker I know of is a Jensen 6" ... Never been a massive fan of the sound though, a bit raspy. 

cbellanga

amazing! would love to see a shot from inside!

77ric

If you knock up any more I assume you plan to sell them, in which case how much do you you would sell these for? 

Looks ace by the way, need to hear some clips. 

DartmoorHedgehog

That's very cool.  Nice wrinkle-free tolexing around the vent hole as well.

4114Effects

DartmoorHedgehog said:

That's very cool.  Nice wrinkle-free tolexing around the vent hole as well.

Heat, patience and a fair amount of swearing ...