Adding a "touch response" circuit

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d2camero
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Joined: Sat Oct 14, 2006 8:35 pm
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Adding a "touch response" circuit

Post by d2camero »

Hi All, I have an 18W and my buddy complains that it lacks touch reponse/feel. I know what he means, sometimes I feel as if the amp is disconnected from the guitar(?!?!)

He pointed out that komet has a touch response circuit. I have looked arouns here and not have found anything definitive indicating this type of circuit - can someone suggest a schematic or a circuit mod?

thanks
Don
rfgordon
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Re: Adding a "touch response" circuit

Post by rfgordon »

In my experience, which is, I admit, somewhat limited, one of the most important factors in touch response is getting the right voltages on the peanuts. A lot of production amps have low voltages in order that the amp "forgive" the crappy touch of the people that buy them. Check the voltages on some of the files in the Trainwreck section or the clean part of the Dumbles and go experiment. And you might try a high-quality, low capacitance cable, as they also make quite a difference.
Rich Gordon
www.myspace.com/bigboyamplifiers

"The takers get the honey, the givers get the blues." --Robin Trower
d2camero
Posts: 72
Joined: Sat Oct 14, 2006 8:35 pm
Location: Canada West Coast

Re: Adding a "touch response" circuit

Post by d2camero »

thanks for the info Rich. No problem measuring voltages and replacing parts etc. Although you'll have to help me out with the lingo - "peanuts"?

BTW I use George L and I have no problems with the same setup when running through our either of our Rivera amps.

Anyone know of the Komet circuit for "touch response"?

Anyone know what aspects of the cicuit affect touch response?

thanks
d1
Normster
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Re: Adding a "touch response" circuit

Post by Normster »

The Touch Response circuit splits the plate resistor for the last gain stage. It uses a 22k and an 82k resistor and sends the signal from either 22k or 104k depending on the switch position. (The plate always sees 104k.)

This circuit will NOT provide added touch response, it will only soften the response. I tried it on my TW Express and didn't like it.
d2camero
Posts: 72
Joined: Sat Oct 14, 2006 8:35 pm
Location: Canada West Coast

Re: Adding a "touch response" circuit

Post by d2camero »

Norm! Hey thats great - I did find a circuit like that in the schematics section (express variation #2). Sad to hear that it softens the feel, *but* I really think I have a build problem with my 18W(i.e. maybe GZ34 rect is not the right tube, or bad filter caps...)

This would be a nice variation to add - just to check it all out.

thanks
d1
rfgordon
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Re: Adding a "touch response" circuit

Post by rfgordon »

Lo siento on the lingo! "Peanuts" or p-nuts refers to the preamp tubes, since they're small. Not as small as the micro-miniature tubes, and not nearly as small as those ill-fated, short-lived aluminum eentsy-weentsy tubes (whose names escape me) that debuted at the dawn of transistors. Imagine a tube the size of a Mallory 150!

Anyway, good luck with your amp. Simple circuit + quality components + adequate voltage + efficient speaker = great tone and great touch.
Rich Gordon
www.myspace.com/bigboyamplifiers

"The takers get the honey, the givers get the blues." --Robin Trower
d2camero
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Joined: Sat Oct 14, 2006 8:35 pm
Location: Canada West Coast

Re: Adding a "touch response" circuit

Post by d2camero »

Rich, thanks for the info. I like your simple saying:
Simple circuit + quality components + adequate voltage + efficient speaker = great tone and great touch
Keeps it all in perspective...

Don
doctord02
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Re: Adding a "touch response" circuit

Post by doctord02 »

d2camero wrote:*but* I really think I have a build problem with my 18W(i.e. maybe GZ34 rect is not the right tube, or bad filter caps...)
Don, if I could offer my two cents; double check your 18 watt for errors or a bad component before changing the circuit... My experience is that the 18 watt circuit is one of the single most 'touch responsive' amps around. Playing dynamics and distortion can all be controlled merely by your pick attack.

If it's a homebrew build, see if the guys over at 18watt.com can help you troubleshoot it... Many of the same folks hang out here as well.

Good luck-

Dave
krash
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Re: Adding a "touch response" circuit

Post by krash »

I think the question was about an 18W with TMB...
-josh
--
Revelation Guitar Amplifiers
http://www.revelationamps.com
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