Distortion pedal build - Page 10

shanx · 17th May 2012, 08:22 PM

2 watts is very respectable. Could consider a dc voltage multiplier circuit for the HT? power off a 12 Vdc wall wart? just some ideas. I think the 12AT7 has more current drive capability as an SE power output than AX7 or AU7, but I could be wrong. The push pull idea I like a lot.

razorrick1293 · 17th May 2012, 10:21 PM

I was thinking more a 12VAC wall wart with a 12-240 v transformer, though i have been meaning to try out a flyback converter in something. I havn't found too much difference between a 12AT7 and AU7 in the output position, bias may be sligtly different. With a DC multiplier i think it should definatelly be push pull, could introduce some nasty harmonics in SE if it isnt filtered properly, which would probably end up fairly inefficient.

Simon B · 17th May 2012, 11:54 PM

Good to see you boys still working out new ways to mess up guitar signals!

See what triodes do operating with some positive voltage on the grid to give some acceleration to electrons coming off the cathode, with the anode voltage low. As the grid is very close to the cathode, a comparatively small positive voltage on it will give the same sort of field strength that a much higher voltage on the anode would....

With grid current flowing the impedance looking into the grid will be lower than normal, so drive requirements will be higher, but it will be a non-linear impedance - more distortion so long as you don't feed it too well ...

shanx · 18th May 2012, 01:37 PM

Yes Simon I think this ought to be fun . Razorrick has some good ideas going.
Right now I have my parts in to do a smallish 5 watt SE. There are a few things I plan to do on the preamp V1 and V2 stages regarding their biasing ''arrangements''. The tube diode pair will be setup between pre and output stages. Normal output SE saturation imparts a different sound than AB operating Push Pull, and I want to bridge the gap so to speak with the diode setup, and see what happens. Tube diodes will be interesting. More glowing stuff is always nice too.

razorrick1293 · 18th May 2012, 05:37 PM

i was also thinking today, about the effects a neon may have for clipping, itl need a 300v supply, but with a 240v transformer that should be achievable, might even make a nice "distort-o-meter"

Simon B · 18th May 2012, 06:23 PM

Quote:

Originally Posted by razorrick1293

i was also thinking today, about the effects a neon may have for clipping, itl need a 300v supply, but with a 240v transformer that should be achievable, might even make a nice "distort-o-meter"

You'd have to make sure that the neon never went out - extinction and striking make nasty transients, sound really bad - but who knows you might even like that!

razorrick1293 · 18th May 2012, 06:45 PM

hehe, it is a distortion box after all

and to be honest, ive blended a few nasty effects to get some decent sounds, mainly diode distortion with all out fuzz touched into a normal overdrive, a parrallel effect box can give so much more possibility than just running through some pedals.

shanx · 18th May 2012, 07:12 PM

Razorrick, I know we said ''all tube'', guess a neon could be considered a tube! Ok I may use a couple of elements not tube, but not in the signal path. Just for DC stabilized biasing and power supply rectification purposes.

I built an optical fuzz once. IR emitter and IR photodarlington It was interesting but kind of a one trick pony.

razorrick1293 · 18th May 2012, 07:18 PM

well, i wouldnt exactly class a neon as solid state! I agree SS rectification would be best, expcially seeing as its not really an exceptionally high voltage idea, I might leave the diode biasing for this, I like it for Music, not so much for guitar, i prefer to have the high/mid boost.

That sounds interesting, one trick pony as in it was fuzz or no fuzz?

shanx · 18th May 2012, 07:26 PM

Yeah, you could vary the fuzz level a bit but the photodarlington squares up really fast. One thing that was cool, was there isn't a lot of associated noise coming from a high gain audio stage clipping. Very synthesizer like sound. Suppose you could add some filtering, integration circuits and such to get into Moog style.

17th May 2012, 11:54 PM	#93
Simon B diyAudio Member Join Date: Dec 2011 Location: North-East England	Good to see you boys still working out new ways to mess up guitar signals! See what triodes do operating with some positive voltage on the grid to give some acceleration to electrons coming off the cathode, with the anode voltage low. As the grid is very close to the cathode, a comparatively small positive voltage on it will give the same sort of field strength that a much higher voltage on the anode would.... With grid current flowing the impedance looking into the grid will be lower than normal, so drive requirements will be higher, but it will be a non-linear impedance - more distortion so long as you don't feed it too well ... __________________ Engineer: One who can do for 10 shillings what any fool can do for 10 pounds.

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17th May 2012, 08:22 PM	#91
shanx diyAudio Member Join Date: Dec 2010 Location: Quebec	2 watts is very respectable. Could consider a dc voltage multiplier circuit for the HT? power off a 12 Vdc wall wart? just some ideas. I think the 12AT7 has more current drive capability as an SE power output than AX7 or AU7, but I could be wrong. The push pull idea I like a lot.

17th May 2012, 10:21 PM	#92
razorrick1293 diyAudio Member Join Date: Nov 2010 Location: England Hertfordshire	I was thinking more a 12VAC wall wart with a 12-240 v transformer, though i have been meaning to try out a flyback converter in something. I havn't found too much difference between a 12AT7 and AU7 in the output position, bias may be sligtly different. With a DC multiplier i think it should definatelly be push pull, could introduce some nasty harmonics in SE if it isnt filtered properly, which would probably end up fairly inefficient.

18th May 2012, 01:37 PM	#94
shanx diyAudio Member Join Date: Dec 2010 Location: Quebec	Yes Simon I think this ought to be fun . Razorrick has some good ideas going. Right now I have my parts in to do a smallish 5 watt SE. There are a few things I plan to do on the preamp V1 and V2 stages regarding their biasing ''arrangements''. The tube diode pair will be setup between pre and output stages. Normal output SE saturation imparts a different sound than AB operating Push Pull, and I want to bridge the gap so to speak with the diode setup, and see what happens. Tube diodes will be interesting. More glowing stuff is always nice too.

18th May 2012, 05:37 PM	#95
razorrick1293 diyAudio Member Join Date: Nov 2010 Location: England Hertfordshire	i was also thinking today, about the effects a neon may have for clipping, itl need a 300v supply, but with a 240v transformer that should be achievable, might even make a nice "distort-o-meter"

18th May 2012, 06:45 PM	#97
razorrick1293 diyAudio Member Join Date: Nov 2010 Location: England Hertfordshire	hehe, it is a distortion box after all and to be honest, ive blended a few nasty effects to get some decent sounds, mainly diode distortion with all out fuzz touched into a normal overdrive, a parrallel effect box can give so much more possibility than just running through some pedals.

18th May 2012, 07:12 PM	#98
shanx diyAudio Member Join Date: Dec 2010 Location: Quebec	Razorrick, I know we said ''all tube'', guess a neon could be considered a tube! Ok I may use a couple of elements not tube, but not in the signal path. Just for DC stabilized biasing and power supply rectification purposes. I built an optical fuzz once. IR emitter and IR photodarlington It was interesting but kind of a one trick pony.

18th May 2012, 07:18 PM	#99
razorrick1293 diyAudio Member Join Date: Nov 2010 Location: England Hertfordshire	well, i wouldnt exactly class a neon as solid state! I agree SS rectification would be best, expcially seeing as its not really an exceptionally high voltage idea, I might leave the diode biasing for this, I like it for Music, not so much for guitar, i prefer to have the high/mid boost. That sounds interesting, one trick pony as in it was fuzz or no fuzz?

18th May 2012, 07:26 PM	#100
shanx diyAudio Member Join Date: Dec 2010 Location: Quebec	Yeah, you could vary the fuzz level a bit but the photodarlington squares up really fast. One thing that was cool, was there isn't a lot of associated noise coming from a high gain audio stage clipping. Very synthesizer like sound. Suppose you could add some filtering, integration circuits and such to get into Moog style.