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DIY Stompboxes => Building your own stompbox => Topic started by: crane on November 29, 2014, 07:00:25 PM

Title: boosting low gain tube amps
Post by: crane on November 29, 2014, 07:00:25 PM
OK - it is late at night and I am thinking about geeky stuff - a friend of mine plays in a kind of a post pop band - usually a tele through bassman. He always complains that there is no way he can get the preamp to saturate. I am thinking that an 18V hi gain booster could help him. Has this been done in the past?
any videos/clips/tips?
Title: Re: boosting low gain tube amps
Post by: davent on November 29, 2014, 07:52:01 PM
Breadboard a SHO and/or AMZ Mosfet Booster and see if they do what you want. Both simple, low parts count builds with all kinds of gain to hammer the first preamp stage.  A Super Duper 2 in 1, (2 SHO's in series) is even more fun.
dave
Title: Re: boosting low gain tube amps
Post by: Scruffie on November 29, 2014, 09:36:34 PM
Look for merlin's circuit the glass blower, that should do the job nicely.
Title: Re: boosting low gain tube amps
Post by: PRR on December 01, 2014, 04:12:07 PM
> tele through bassman.

There must be 13 different things sold as "Bassman".

The 5F6a with 12AX7 in the first holes is historically "loud", but indeed the preamp was scaled to NOT overload on instrument level inputs. A booster with 3V supply would barely clip the input. A good booster on 9V supply should give significant flavor. Indeed you might need >9V to truly "punk-out". Or turn to a less polite amplifier.

> Has this been done in the past?

That is WHAT the LPB was made for, and why it has been sold (and cloned) for 40+ years.

SHO or AMZ should also work.
Title: Re: boosting low gain tube amps
Post by: GibsonGM on December 01, 2014, 07:30:24 PM
+1    LPB (Linear Power Booster, built just for this as Paul described) would probably sound good and is easy, but I prefer the AMZ Mosfet Boost, myself.  Running a Hot Rod Deluxe which is "similar" in nature to the Bassman - sort of a modern clone.   That gives me blues tones thru Stevie Ray.

To REALLY warm things up (more to the Aerosmith/Nugent tones), I use a Timmy and use the AMZ (which is pretty transparent) to boost for leads, just my setup and preferences tho....
Title: Re: boosting low gain tube amps
Post by: crane on December 03, 2014, 04:23:22 PM
Thank you everybody for the input.
To be precise - his bassman is Bassman 135.
The main question is if it is worth going for bigger headroom than 9V pedals.
Stacking two SHOs in series would result in one overloading the other, wouldn't it?
Title: Re: boosting low gain tube amps
Post by: PRR on December 03, 2014, 11:23:22 PM
The 135 is an incredibly BIG yet Clean amp.

Many people don't like such a mild amp for guitar.

There's many new-made 50W amps which will overload and "dirt-up" better than a 135 and less to carry.

> one overloading the other

Worth a try. Cascaded distortion is a Thing. If it is too much, use one and trade the other to another player.
Title: Re: boosting low gain tube amps
Post by: StarGeezers on December 05, 2014, 09:46:37 AM
  And then , sometimes you only need a little boost .... not the extreme...   :icon_neutral:
Title: Re: boosting low gain tube amps
Post by: Scruffie on December 06, 2014, 08:02:00 AM
Quote from: Scruffie on November 29, 2014, 09:36:34 PM
Look for merlin's circuit the glass blower, that should do the job nicely.
Really think you should look at this, it sounds much more like what you're after than has been suggested.

http://www.valvewizard.co.uk/glassblower.html