2xEL34 vs. 4xEL84 vs. 2x6L6 vs. 4x6V6 - Page 2 - diyAudio
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Old 11th September 2006, 01:56 AM   #11
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Quote:
Originally posted by tubelab.com


I have crossed over to the dark side, by designing a microprocessor controlled vacuum tube guitar amp. It is far from complete, and I don't have the time to work on it, but here is the idea. A P-P tube amp of about 50 watts depending on mode (triode, UL, pentode), 3 different preamp sections, clean, overdriven, and solid state (opamps).
GASP! you heretic! Just kidding. I have been waiting for someone to tackle that very project foe quite a while. Soldano flirted with it in the x99 preamp with the Caswell-designed motorized interface, but that is the only one that i have seen.

Good Luck with it man. I'll check the tubelab for progress.

Personally, for myself I build up my own amps and tweak tweak tweak, play out and tweak tweak again, and when I get a circuit and a tone stack setting that i am happy with, I hard wire the sucker, replacing the pots with fixed resistors and don't look back. BUT I was a chronic knob fiddler myself in the past.
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Old 11th September 2006, 11:31 AM   #12
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Default tubelab about said it all

I have experimented with many different components & tube operating parameters in guitar amps. This comes from years of experience in changing the sound of many amps to suit musicians needs.

Changing one component that effects sonics greatly is the speaker. That can make or break an amp in my opinion. Although not a solid-state person, I swapped the stock speaker of a Crate GX60 to a Jensen MOD. The change took the amp from lousy to acceptable.

A few tricks worthwhile are changing coupling caps. For less clean sound, I like ceramic coupling caps in the preamp section. Perhaps swapping just one or a few caps will work for you. For the most part, I like Sprague 715P coupling caps at the power tube grid(s).

As for power tubes, I notice customers seem to follow a certain tube type with an associated sound, yet I find other changes effects the Tone more than a power tube type. I also noticed fixed bias makes for a cleaner sound vs cathode bias on a power tube.

I tune amps with different manufactures of tubes. And, preamp tubes of same manufacture sound different in different circuits.

Finally, a tube rectifier vs solid-state effects the overall feel of a guitar amp.

My 2 cents.
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Old 11th September 2006, 11:50 AM   #13
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Quote:
Originally posted by tubelab.com
I have crossed over to the dark side......
....and I to the light side regarding guitar amplifiers! I will probably never be engaged to design one, but at least I now have an idea of what it is all about, after all these contributions. Tubelab, success with your idea.

Regards.
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Old 12th September 2006, 02:49 AM   #14
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Soldano flirted with it in the x99 preamp with the Caswell-designed motorized interface, but that is the only one that i have seen.
I got the idea when I bought an ADA MP-1 midi guitar preamp on Ebay about 5 years ago. It has several "custom" sounds stored it it that were saved by the previous owner, and a few saved my me.

People either love the sound of this thing, or hate it, I am in between. It is horrendously microphonic, and it has enough gain when maxed to make your guitar cord microphonic! The user interface sucks, especially for a live situation, unless you use a midi controller. I have seen one used live with a foot switch controller that had 6 stomp switches which sent out midi messages. That worked well, but costs a bundle of cash.

I figured that I would take the good ideas from this setup, and build it all into an amp. I have a hardware evaluation board from Microchip, and I have been experimenting with the processor hardware, and attempting to write "C" code for it.

So much for the sandy stuff. I got this brilliant idea (hey I'm a blonde, most of my ideas make smoke) that I could have 4 or 6 output tubes in the amp and turn different tubes as needed by processor control. All you need to do this is a HV mosfet in the cathode circuit. Then it comes to you that they dont have to be the same tubes. I wired two 6v6's on one side of the push pull transformer, and 1 6L6 to the other side of the OPT Call this asymetrical push pull. It sounded absolutely wicked. I played with this for two days until I got too carried away with the voltage knob on my power supply. I saw flames shooting out of the OPT, so I can assume that the tubes are toast! That was 4 months ago, I haven't even tried to figure out what happened, and how much stuff is fried.
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Old 12th September 2006, 06:16 AM   #15
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LOL! Just think of it this way: you made a nice flamethrower.

i just made one myself... found an old Amperex PT of unknown current rating and thought.... well, it should be able to do a pair of el84's in AB1... then i pushed it to A1, then replaced them with 6CA7's--BAD idea! After 5 minutes of beautiful music it bacame an instant flamethrower. I don't know what Amperex coated those trannys in, but it sure does stink when it is on fire!
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Old 12th September 2006, 09:12 AM   #16
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...... and I always thought those stage effects were tone channel activated spots and theatre smoke!
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