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

["Rick Davis" <bluesharpamps@xxxxxxxxx>]

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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