This is off topic for my thread, but I had so much fun, I need to post it 
.
I dug in @ my workbench yesterday and put together a simple champ style amp.. I just used my bench power supply, so that took all of 1/2 hour, and I was about to start trying other things when my modular synth caught my eye....
I put the tubes aside and built a little 20x op-amp amplifier to get the guitar up to modular synth levels, threw together a little envelope follower.. Played the guitar through my various wave multipliers, filters, reverb, ring mod, etc.. wow wow wow!!! Since I have a keyboards/synth background, this was super super fun.. Used the master clock of my synth to modulate lfo's, and tick along a metronome (or beat), so everything was in time. It's the ultimate guitar fx rack!
So anyway.. in my spare time today, I'll get back to working on amplifier ideas. Thanks everyone for getting me over the initial indecisive hump of this project.
If anyone's still reading, back on topic to amps, is there a big difference in tone or distortion w/ triode vs pentode? I'm thinking about using the pp 6v6 outputs in triode, to keep the max power down.
And for phase splitter, any reason to choose ltp over cathodyne? I'm thinking about using an existing chassis w/ only 2 '9 pin' size holes.. And maybe I'd get enough gain using 3 triode sections for gain, and one for phase splitting.
. I dug in @ my workbench yesterday and put together a simple champ style amp.. I just used my bench power supply, so that took all of 1/2 hour, and I was about to start trying other things when my modular synth caught my eye....
I put the tubes aside and built a little 20x op-amp amplifier to get the guitar up to modular synth levels, threw together a little envelope follower.. Played the guitar through my various wave multipliers, filters, reverb, ring mod, etc.. wow wow wow!!! Since I have a keyboards/synth background, this was super super fun.. Used the master clock of my synth to modulate lfo's, and tick along a metronome (or beat), so everything was in time. It's the ultimate guitar fx rack!
So anyway.. in my spare time today, I'll get back to working on amplifier ideas. Thanks everyone for getting me over the initial indecisive hump of this project.
If anyone's still reading, back on topic to amps, is there a big difference in tone or distortion w/ triode vs pentode? I'm thinking about using the pp 6v6 outputs in triode, to keep the max power down.
And for phase splitter, any reason to choose ltp over cathodyne? I'm thinking about using an existing chassis w/ only 2 '9 pin' size holes.. And maybe I'd get enough gain using 3 triode sections for gain, and one for phase splitting.
Triode/Pentode switch maybe?
This classic schematic has 3 triode sections and the cathodyne phase splitter.
http://support.fender.com/schematics/guitar_amplifiers/57_Deluxe_Fender_57_schematic.pdf
That amp sounds great.
I think you are talking at the power stage.
Some amps have pentode/triode switches (JCM900 for example).
Not too useful: they are still very loud and sound loses bite, sounds soft in a bad way.
If you want to lower power keeping the sound lower +B voltage.
You can have a 2 position switch like in Orange Tiny terror (7/15W) or continuous +V control using a MosFet.
See above.
LTP wins hands down.
Cathodine distorts ugly, period.
And you save nothing: since cathodine has unity gain, you still need an extra triode to provide it (unless you want a power amp with 60V RMS sensitivity
) while the LTP, which uses 2 triodes, does have full tube gain.In both cases: 2 triodes for a normal power amp.
I think you are talking at the power stage.
Some amps have pentode/triode switches (JCM900 for example).
Not too useful: they are still very loud and sound loses bite, sounds soft in a bad way.
If you want to lower power keeping the sound lower +B voltage.
You can have a 2 position switch like in Orange Tiny terror (7/15W) or continuous +V control using a MosFet.
See above.
LTP wins hands down.
Cathodine distorts ugly, period.
And you save nothing: since cathodine has unity gain, you still need an extra triode to provide it (unless you want a power amp with 60V RMS sensitivity
In both cases: 2 triodes for a normal power amp.
I agree with all of this.Hey Wicked
I'm gonna chime in here. I built a trainwreck clone with 6V6 output tubes. I then added a VVR (variable voltage regulator)circuit, which behaves like a master volume. From the first post, I think you can achieve what you are looking for by installing a VVR. It's basically a MOSFET circuit that allows you to control how much output power you hear. You can use any standard guitar circuit(tons out there) with enough gain (at least 3 gain stages IMHO). You can then crank your guitar volume, the preamp volume fully dimed and turn down the output power to bedroom levels if you like. You can get the distorted sounds you're looking for at bedroom level power.
I'm gonna chime in here. I built a trainwreck clone with 6V6 output tubes. I then added a VVR (variable voltage regulator)circuit, which behaves like a master volume. From the first post, I think you can achieve what you are looking for by installing a VVR. It's basically a MOSFET circuit that allows you to control how much output power you hear. You can use any standard guitar circuit(tons out there) with enough gain (at least 3 gain stages IMHO). You can then crank your guitar volume, the preamp volume fully dimed and turn down the output power to bedroom levels if you like. You can get the distorted sounds you're looking for at bedroom level power.
I built this today. The random parts I had on hand dictated my component choices/values.
No tone control, because I need some pots and caps... But it's got plenty of gain, so can certainly handle tone adjustments when I get the parts.
It sounds great! I don't have much experience w/ guitar amps, but it's completely different from my magnetone amp.. This one distorts very well. Too much at the highest volume settings, maybe. I don't have a volume pot on the amp yet, but using the guitars volume, 1-3 is clean, 4-8 is varying levels of good distortion, and 9-10 is getting nasty sounding.
Poacher (and maybe someone else mentioned it earlier too), thanks, a VVR seems to be exactly what I'm looking for.
Let me know if there's anything wrong w/ the schematic I came up with. It's basically based off the ampex speaker amp it started off as, blended w/ guitar amp component values. It'll grow from here. Tone controls, pentode mode, and vvr are next.
No tone control, because I need some pots and caps... But it's got plenty of gain, so can certainly handle tone adjustments when I get the parts.
It sounds great! I don't have much experience w/ guitar amps, but it's completely different from my magnetone amp.. This one distorts very well. Too much at the highest volume settings, maybe. I don't have a volume pot on the amp yet, but using the guitars volume, 1-3 is clean, 4-8 is varying levels of good distortion, and 9-10 is getting nasty sounding.
Poacher (and maybe someone else mentioned it earlier too), thanks, a VVR seems to be exactly what I'm looking for.
Let me know if there's anything wrong w/ the schematic I came up with. It's basically based off the ampex speaker amp it started off as, blended w/ guitar amp component values. It'll grow from here. Tone controls, pentode mode, and vvr are next.
Attachments
If you like the sound then there is nothing wrong with it.
If you add a tone stack you could lose as much as 80% of your gain, and maybe your tone as well - don't ask me how I know.
DIY is about trying it for yourself - 1/2 a dozen tone stacks you could try.
Could also replace EF 86 with a 6u8 or 6bl8 etc. That would give a pentode and a triode without needing another tube socket, recovering the gain lost in the tonestack.
And VVR's rock.
If you add a tone stack you could lose as much as 80% of your gain, and maybe your tone as well - don't ask me how I know.
DIY is about trying it for yourself - 1/2 a dozen tone stacks you could try.
Could also replace EF 86 with a 6u8 or 6bl8 etc. That would give a pentode and a triode without needing another tube socket, recovering the gain lost in the tonestack.
And VVR's rock.
I figured tone controls after a pentode could be an issue, so started looking for other similar designs.. Only a few out there. In the end, I basically cut-pasted in the tone stack out of the "route 66" amp.
I like it! still have enough gain for good distortion. The tone controls work.. (I don't know.. Tone controls don't excite me all that much.. I guess, again, synth background, I'm used to DRAMATIC shaping and filtering, not this subtle tone stuff).
The distortion though, compared to my clean magnetone, is amazing... Sounds really good and I don't want to put the guitar down!
All in all, great project, re-used an old chassis and transformers, so cost nothing and only took a few hours to build. Plenty of guitar playing time left over.
I like it! still have enough gain for good distortion. The tone controls work.. (I don't know.. Tone controls don't excite me all that much.. I guess, again, synth background, I'm used to DRAMATIC shaping and filtering, not this subtle tone stuff).
The distortion though, compared to my clean magnetone, is amazing... Sounds really good and I don't want to put the guitar down!
All in all, great project, re-used an old chassis and transformers, so cost nothing and only took a few hours to build. Plenty of guitar playing time left over
.Why not try the 6BL8 like suggested and directly couple the pentode to the triode as a cathode follower to drive the tone stack...........or if you don't want the tone stack have the cathode follower drive an effects send/return and place a equalizer in there or whatever you like for more dramatic effects.
As of now, because I don't have any, and did have the ef86.
But I will take your advice for the next expansion phase, when I add the send/'return or build a reverb into it.
Send/return probably makes more sense than building the reverb into the amp, and maybe I'll set up a patchable fx/eq rack to 'match' the amp. I built a tube resonant filter and a tube wave folder several years ago as the start of a vacuum tube modular, but never followed through with it. I'll see if they do interesting things w/ the guitar.. Now it's turning in to a loooong term project.
But I will take your advice for the next expansion phase, when I add the send/'return or build a reverb into it.
Send/return probably makes more sense than building the reverb into the amp, and maybe I'll set up a patchable fx/eq rack to 'match' the amp. I built a tube resonant filter and a tube wave folder several years ago as the start of a vacuum tube modular, but never followed through with it. I'll see if they do interesting things w/ the guitar.. Now it's turning in to a loooong term project.
And here's a link with a lot more info.
http://www.guitarstudio.tv/documents/Designing-V-T-Amplifiers.pdf
http://www.guitarstudio.tv/documents/Designing-V-T-Amplifiers.pdf
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