VOX VT-30 amplifier repair!

 Vox VT-30

This Vox vt-30 modelling amplifier was brought in with a few problems. There was a bit of volume drop and a tremolo-like issue. Being a hybrid amp, I had to check the on board single 12ax7 preamp tube for signs of wear.
Dust in the wind...
 Therefore, I opened up the amp and I found loads of dust and a few rusty parts inside. I cleaned the amp thoroughly and then used some contact cleaner spray for the potentiometers(pots). Dust is the No1 enemy of the guitar and amp pots. Anyone could clean these pots using compressed air and contact cleaner spray.





Tube change:
  Once I cleaned the amp, I put the chassis together to check the on board tube. The stock Chinese no-name tube was very old and it was a bit microphonic. So I replaced it with a new EH 12ax7b one and the result was very good. There was no volume drop any more and the tone got just a little bit more character.

Speaker change:
  I noticed that the vt-30 has a no-name 10" stock speaker. A friend of mine had another vox vt amp and brought in a Celestion BL-10 bass/guitar 10" speaker to try on. The result was way better! The tube change did make some difference in tone but the speaker change had such an impact that we couldn't believe it!... The stock VT tones were so much fatter, with fuller mids, more character and really good through the celestion speaker. We also managed to get a few more dBs !
  The stock "made in Vietnam" vox vt speaker was probably intended for inefficient hi-fi speaker use.
The best part is that the BL-10/100W/8ohm speaker cost only 20euros! Value for money!
http://www.thomann.de/gr/celestion_bl10100_16_ohms.htm

Verdict
 The amp sounds much better with a new tube and speaker on. Nevertheless, the stock VT modelling sounds lack a bit of note definition. The noise gate is a bit harsh, making legatos sound weak and playing dynamics are really not that good.
 Some stock Dist/OD patches are not suitable for lead guitar playing and solos as there's not much gain/sensitivity available and the noise gate makes things worse... The solution would be to use a clean booster pedal or a mild overdrive stompbox in front of the amp to get that extra gain for lead playing.

Here are a few pictures of the actual amp: