hey guitar playas, try this one!

noisenyc · 24th June 2005, 03:01 PM

Peter M. · 24th June 2005, 05:46 PM

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 · 27th June 2005, 11:50 AM

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 · 27th June 2005, 04:57 PM

Looks pretty cool

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

noisenyc · 27th June 2005, 05:50 PM

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

Tom Bavis · 28th June 2005, 01:00 AM

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 · 28th June 2005, 11:42 AM

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 · 28th June 2005, 02:58 PM

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 · 28th June 2005, 07:43 PM

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.

24th June 2005, 03:01 PM	#1
noisenyc diyAudio Member Join Date: Dec 2004 Location: los angeles	hey guitar playas, try this one! __________________ -blackie.

27th June 2005, 11:50 AM	#3
noisenyc diyAudio Member Join Date: Dec 2004 Location: los angeles	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. __________________ -blackie.

27th June 2005, 04:57 PM	#4
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Looks pretty cool Can I parallel OPT's to make it? Say 2 6V6/EL84 OPT's? __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

27th June 2005, 05:50 PM	#5
noisenyc diyAudio Member Join Date: Dec 2004 Location: los angeles	i generally use a vintage plexi marshall 50w opt. 3.8k primary, but you can do...whateva! __________________ -blackie.

28th June 2005, 11:42 AM	#7
noisenyc diyAudio Member Join Date: Dec 2004 Location: los angeles	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. __________________ -blackie.


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24th June 2005, 05:46 PM	#2
Peter M. diyAudio Member Join Date: Jan 2005 Location: Østfold	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

28th June 2005, 01:00 AM	#6
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	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...),.

28th June 2005, 02:58 PM	#8
amperex diyAudio Member Join Date: Feb 2005 Location: MI	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.

28th June 2005, 07:43 PM	#9
noisenyc diyAudio Member Join Date: Dec 2004 Location: los angeles	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. __________________ -blackie.

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