Clean to breakup range

yodermr · 5th February 2006, 04:04 PM

In complete laymans terms I'm curious how you get a guitar amp's range from clean to breakup to distorted smaller.

I have been building an amp from an old organ leslie thing I got on Ebay. Using what It had that was of value (OT PT, chassis, Tube configuration, blue Mallory caps, etc) I have it set up as SS rectifier, EL84 push pull, negative feedback w/ presense control, cathode biased, one 12At7 for the phase inverter and another 12ax7 for pre and cathode follower tone controls.

Anyway, I've been playing around with different values on caps and resistors for the plate and cathode on the pre tubes. Really just learning what does what (I don't yet have enough understanding of the calulations to do this with a plan). I can get it to put out a very nice clean OR a pretty decent grind (little loose in the low end)

What I'm curious about is how to go about maintaining a good clean at lower volumes and getting more break up/distortion at high volumes. Getting a better clean/distort range within my volume control range if you will.

Now I'm a novice with enough self taught education to get me to this point, so you might chuckle at me. Hey maybe this is just a basic design tradeoff that I'm just coming to realize.

Thoughts?

aletheian · 5th February 2006, 10:57 PM

I would recommend posting on a more guitar oriented board... like ax84.com. There is a great theory document there too:

http://ax84.com/index.php?pg=project...a/ax84_m35.pdf

And simple load line documemts:

http://ax84.com/dp.php?pg=projects&p.../ax84_m225.pdf

http://ax84.com/dp.php?pg=projects&p.../ax84_m226.pdf

And if you have a schmatic of the amp, the guys there (myself included) will be happy to give you suggested tweaks.

Peace

yodermr · 6th February 2006, 07:45 AM

Thanks for the pointer to the document. That first one made more sense than anything I've found yet. Anything that helps connect what you here versus how you build it really helps.

Still a little lost on how this concept of gain is related to volume and distortion.

I need to sit down, quit being lazy and learn the math for this hobby.

Thanks
Mark

5th February 2006, 04:04 PM	#1
yodermr diyAudio Member Join Date: Dec 2005 Location: In a house, mostly in my home studio whenever I get a chance	Clean to breakup range In complete laymans terms I'm curious how you get a guitar amp's range from clean to breakup to distorted smaller. I have been building an amp from an old organ leslie thing I got on Ebay. Using what It had that was of value (OT PT, chassis, Tube configuration, blue Mallory caps, etc) I have it set up as SS rectifier, EL84 push pull, negative feedback w/ presense control, cathode biased, one 12At7 for the phase inverter and another 12ax7 for pre and cathode follower tone controls. Anyway, I've been playing around with different values on caps and resistors for the plate and cathode on the pre tubes. Really just learning what does what (I don't yet have enough understanding of the calulations to do this with a plan). I can get it to put out a very nice clean OR a pretty decent grind (little loose in the low end) What I'm curious about is how to go about maintaining a good clean at lower volumes and getting more break up/distortion at high volumes. Getting a better clean/distort range within my volume control range if you will. Now I'm a novice with enough self taught education to get me to this point, so you might chuckle at me. Hey maybe this is just a basic design tradeoff that I'm just coming to realize. Thoughts?

5th February 2006, 10:57 PM	#2
aletheian diyAudio Member Join Date: Apr 2004 Location: Philly	I would recommend posting on a more guitar oriented board... like ax84.com. There is a great theory document there too: http://ax84.com/index.php?pg=project...a/ax84_m35.pdf And simple load line documemts: http://ax84.com/dp.php?pg=projects&p.../ax84_m225.pdf http://ax84.com/dp.php?pg=projects&p.../ax84_m226.pdf And if you have a schmatic of the amp, the guys there (myself included) will be happy to give you suggested tweaks. Peace __________________ Heghlu'meH QaQ jajvam!

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6th February 2006, 07:45 AM	#3
yodermr diyAudio Member Join Date: Dec 2005 Location: In a house, mostly in my home studio whenever I get a chance	Thanks for the pointer to the document. That first one made more sense than anything I've found yet. Anything that helps connect what you here versus how you build it really helps. Still a little lost on how this concept of gain is related to volume and distortion. I need to sit down, quit being lazy and learn the math for this hobby. Thanks Mark

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