Re: [Harp-L] Re: Fender Blues Jr Amps



The 12AU7 tube is not interchangable with the 12AX7, even though they share
the same pin out.  The AU7 draws significantly more power and may stress
your power supply.  I stay away from the AU7 when replacing AX7 tubes in
guitar amp to make it more harp friendly.  Instead, I use the 5751 (my
favorite preamp tube for harp) or the 12AY7.  Never use the 12AT7; it is a
horrible tube for tone.  It is a different animal designed for use as a
phase inverter.

Here is a handy chart;

http://thetubestore.com/gainfactor.html

-Rick Davis
The Blues Harp Amps Blog
http://www.bluesharpamps.blogspot.com/



On Thu, Dec 18, 2008 at 3:08 AM, Ian Farquharson <farky@xxxxxxxxxxxxxxxx>wrote:

> The Blues Junior is ok for Harp but exchange a couple of of the pre amp
> tubes for AU 7's...to help with feedback issues,
> I think the Junior Pro is more suitable, no reverb....but the Reverb on the
> Blues Junior is rubbish anyway, but also exchange 1 preamp tube to a AU
> 7....its cheaper too .
>
> The Fender Champion, is cheapest of the lot....but maybe lacks a bit of
> bottom.
> Far better to get a harpgear 2......around the same price of a Blues
> Junior....only 5 watts, but loud.....properly set up for harp with a tube
> rectifier and a line out.
>
> Farky
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