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DIY Stompboxes => Building your own stompbox => Topic started by: royster on October 09, 2012, 06:21:35 AM

Title: Preamp stompbox
Post by: royster on October 09, 2012, 06:21:35 AM

Can anyone suggest a clean preamp stompbox for my pedalboard? I want to connect my pedalboard straight into the power amp section of of my combo and so bypass the preamp in the combo amp  It is a Carvin Amp. I think I need some kind of preamp with tone controls to boost the signal into the power amp
Title: Re: Preamp stompbox
Post by: JebemMajke on October 09, 2012, 02:26:27 PM
Clean or dirty?
If clean go for FET version of Alembic F2B.
Title: Re: Preamp stompbox
Post by: ubersam on October 09, 2012, 03:25:14 PM
Quote from: JebemMajke on October 09, 2012, 02:26:27 PM
Clean or dirty?
If clean go for FET version of Alembic F2B.

I second that, but with some changes.

Here's the Fet2B: http://www.diystompboxes.com/smfforum/index.php?topic=73173.0 (http://www.diystompboxes.com/smfforum/index.php?topic=73173.0)

What I have done:

I took the "Normal" preamp section of the Bassman schematic (AA864 (http://thevintagesound.com/ffg/schem/bassman_aa864_schem.gif), or 6G6 (http://www.thevintagesound.com/ffg/schem/bassman_6g6_schem.gif)) and turn that into a two Fetzer Valve (http://www.runoffgroove.com/fetzervalve.html) stages with a 'marshall' tone-stack in the middle and a 100K volume pot at the very end. J201s weren't clean enough for me so I chose JFETs with higher Vp. I used J305s (Siliconix) but 2N5457s and 2N3819s also work with good results. Also, I'm running the circuit on ~18V using a charge pump.