hey guitar playas, try this one!

[noisenyc]

An externally hosted image should be here but it was not working when we last tested it.

 

[Peter M.]

Interesting, how does it sound?
Have you compared the difference in sound with VR tubes vs. a simple resistor/capacitor for the screens?

Regards,
Peter

 

[noisenyc]

the regulated screens give a punchier sound.

this runs the 6550's at a classic "class a" operating point with 300v on the screens, which makes 'em very happy.

the large plate octal preamp tubes make for excellent tone.

historically 6550 guitar amps sound rather dry and clinical, due to ab operation and overvoltage on the screens, the cheesy way out.

try it! 6550's were designed for audio, and run properly they KILL for guitar. 40 watts in class A.

 

[leadbelly]

Looks pretty cool

Can I parallel OPT's to make it? Say 2 6V6/EL84 OPT's?

 

[noisenyc]

i generally use a vintage plexi marshall 50w opt. 3.8k primary, but you can do...whateva!

 

[Tom Bavis]

Paralleling trnasformers won't change the impedance - ratio is the same. But it DOES double the current capacity... connect two identical 8K transformers in parallel, use half the rated load impedance (4 ohms on the 8 ohm tap, etc...),.

 

[noisenyc]

yes you could go that route fer sher. for different trannie configs tune the feedback loop by ear...

make sure you have upwards of 200 mils available in the 350/350 supply and enough output trannie to handle the juice. the more the merrier here.

i originally did this design in a beater fender chassis as a gift to my friend chris cush who owned Mojo Guitars here in nyc for many years. i made it w/ switchable output impedance so it would run any cabinet.

it ended up in the backline at Continental, where musos beat it senseless for years on a nightly basis. still going strong with only the occaisional tube change.

 

[amperex]

Looks fine business

Look at this guitar amp tube line up on eBay 7332775268. A lot of older tubes provides great sonics. Field coil speaker is a plus as well.

 

[noisenyc]

6sl7 are easy to come by in NOS.

as for 6550...try the EH ones, they are as good a 6550 as ever made, i daresay. excellent sonics and reliability at full rated class A dissipation.