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-   -   ESP Guitar Preamp Output Swing (http://www.diyaudio.com/forums/instruments-amps/150224-esp-guitar-preamp-output-swing.html)

shaan 28th August 2009 09:01 PM

ESP Guitar Preamp Output Swing
 
The page says that for the diodes the power amplifier must have a sensitivity of 750mV for full power. I plan to run it with my 20Watt SE Class-A amp which has a sensitivity of 1.5V for full power.

Is there any way to increase the preamp's output voltage swing while keeping the soft clipping behavior intact?
Are there ways to make the preamp soft-clip by means other than using those diodes at the output?

http://sound.westhost.com/project27.htm

Thanks in advance.



.

nigelwright7557 28th August 2009 10:12 PM

Quote:

Originally Posted by shaan (http://www.diyaudio.com/forums/instruments-amps/150224-esp-guitar-preamp-output-swing-post1909286.html#post1909286)
The page says that for the diodes the power amplifier must have a sensitivity of 750mV for full power. I plan to run it with my 20Watt SE Class-A amp which has a sensitivity of 1.5V for full power.

Is there any way to increase the preamp's output voltage swing while keeping the soft clipping behavior intact?
Are there ways to make the preamp soft-clip by means other than using those diodes at the output?

http://sound.westhost.com/project27.htm

Thanks in advance.



.


Outputs are usually 0dB so perhaps the two values are RMS and peak ?

juma 29th August 2009 12:09 AM

Quote:

Originally Posted by shaan (http://www.diyaudio.com/forums/instruments-amps/150224-esp-guitar-preamp-output-swing-post1909286.html#post1909286)
...Is there any way to increase the preamp's output voltage swing while keeping the soft clipping behavior intact?...

Yes, add another gain stage (another OpAmp, for example) with a gain of 2 (or more) on preamp's output (before the power amp).

nigelwright7557 29th August 2009 12:32 AM

Quote:

Originally Posted by juma (http://www.diyaudio.com/forums/showthread.php?p=1909417#post1909417)
Yes, add another gain stage (another OpAmp, for example) with a gain of 2 (or more) on preamp's output (before the power amp).

Or alter your amp to have twice as much gain.
Its probably one resistor change to double the gain.

juma 29th August 2009 12:48 AM

Quote:

Originally Posted by nigelwright7557 (http://www.diyaudio.com/forums/showthread.php?p=1909436#post1909436)
Or alter your amp to have twice as much gain.
Its probably one resistor change to double the gain.

It might not work if the amp doesn't use a lot of GNFB.
BTW, what power amp are we talking about?

nigelwright7557 29th August 2009 12:50 AM

Quote:

Originally Posted by juma (http://www.diyaudio.com/forums/showthread.php?p=1909443#post1909443)
It might not work if the amp doesn't use a lot of GNFB.
BTW, what power amp are we talking about?

The 20 watt amp he mentions in the first post.

juma 29th August 2009 12:53 AM

Quote:

Originally Posted by nigelwright7557 (http://www.diyaudio.com/forums/showthread.php?p=1909444#post1909444)
The 20 watt amp he mentions in the first post.

Ha, ha, great answer - that much I've read myself.
I suppose the original poster should answer that question...

shaan 29th August 2009 04:12 AM

Quote:

Originally Posted by juma (http://www.diyaudio.com/forums/showthread.php?p=1909417#post1909417)
Yes, add another gain stage (another OpAmp, for example) with a gain of 2 (or more) on preamp's output (before the power amp).

Thanks for the suggestion. On my way. :)

shaan 29th August 2009 04:15 AM

Quote:

Originally Posted by juma (http://www.diyaudio.com/forums/showthread.php?p=1909443#post1909443)
It might not work if the amp doesn't use a lot of GNFB.
BTW, what power amp are we talking about?

It's a common drain MOSFET power follower driven by DoZ preamp, modified with the maximum suggested gain in the article.

http://sound.westhost.com/project83.htm

shaan 29th August 2009 04:19 AM

Plus, I was wondering whether any kind soul would answer my second question or not?
"Are there ways to make the preamp soft-clip by means other than using those diodes at the output?"


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