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Author Topic: Add a tube preamp on Randall RG100G3 Plus  (Read 872 times)

zadmight

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Add a tube preamp on Randall RG100G3 Plus
« on: August 17, 2017, 09:15:44 AM »

Hi all,
I got a Randall Rg100G3 Plus for free and I want to try to modify the sound of this amp.  I want to add a Ecc83 preamp tube. I got the schematic from Randall and I thought to "cut and paste" a parte of the preamp circuit...

I'm still completing the soldering and do the test in a few days. What do you think about this idea? Everyone tried this before?

Thanks for your suggestions  :)
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J M Fahey

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Re: Add a tube preamp on Randall RG100G3 Plus
« Reply #1 on: September 10, 2017, 11:18:11 PM »

Dunno, you tell us  :tu:
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zadmight

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Re: Add a tube preamp on Randall RG100G3 Plus
« Reply #2 on: September 11, 2017, 03:52:03 AM »

I did it but the result wasn't what I expected  :( ... the sound is still pretty "cold"

I roll back and then start building a Guitar Tube Pedal... Hope to get some more warm sound this way
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g1

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Re: Add a tube preamp on Randall RG100G3 Plus
« Reply #3 on: September 11, 2017, 12:13:41 PM »

The tube in the drawing runs off a 375V supply.
Is that what you are running it at?
« Last Edit: September 12, 2017, 02:04:34 PM by g1 »
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J M Fahey

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Re: Add a tube preamp on Randall RG100G3 Plus
« Reply #4 on: September 12, 2017, 05:06:46 AM »

I did it but the result wasn't what I expected  :( ... the sound is still pretty "cold"

I roll back and then start building a Guitar Tube Pedal... Hope to get some more warm sound this way
Ouch !!!   :(
Thanks for experimenting and taking your time to share  :dbtu:
Problem is (IF that´s a problem) that Randalls are designed for that Pantera like brutal sound, quite the opposite of "warm",  so modding just one section will help somewhat but not fully.

Our friend Phatt has experimented a lot on getting good warm and punchy sound out of SS amps, his main point being a clever tweaking of bandwidth and frequency response to keep warmth and lose harshness, so take your time to search and read his posts, and listen to some samples uploaded here, it is very much worth it.

KMG has also uploaded killer JCM800 emulations, also search and listen at them.

Maybe you should try some of those projects, and keep your Randall as a power amp and speakers platform to amplify them, bypassing its own preamp.
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