Guitar Dreamer: Harley Benton GA-5 mod

Here's a new mod on the classic Harley Benton GA-5 amp. It's a classic 5W tube amp head with a 12AX7 and an EL84 tube. This amp was produced for years as an Epiphone valve junior alternative and sold for 89euros at thomann.de! It's now a discontinued product but anyone looking for an affordable 5W tube head could check out the new Kustom defender 5h (sold for 115 Euros).

http://www.thomann.de/gb/kustom_defender_5h.htm?partner_id=73786

Other tube amp heads:
www.thomann.de/gb/cat.html?gf=tube_guitar_heads&oa=pra?partner_id=73786

And since this amp is no longer produced by Benton, check out their latest Fender-style Tube amp monsters!
www.thomann.de/gb/harley_benton_vt_30_rd.htm?partner_id=73786
www.thomann.de/gb/harley_benton_vt_30_bk.htm?partner_id=73786

There are lots of mods for this Harley Benton amp on the Internet but a friend of mine wanted a simple and essential mod. The amp had originally a Volume (more of a "gain" pot) and an EQ control(more like a "bass/contour" control).
We decided to add a 1Mohm "master volume" control before the el84 and keep the stock "volume" control as a gain pot. In order to get more gain, I removed the R1 and R5 resistors. This mod made the amp much more versatile in terms of tone and headroom. But there just wasn't enough headroom!... That's because there was a huge voltage drop across the EQ tonestack and the power amp sounded like it was 2W instead of 5W... So we put an EQ bypass switch in there to compensate for the signal loss when volume and extra power is required. The EQ bypass switch is placed between the R19 and the ground.

So here is the original schematic for the ga5 amp:
http://www.sewatt.com/files/sewatt/HB-GA5-Stock_0.pdf