#1
Hi all,

I have a Blackstar HT-5 Combo (had it about a year) and a handful of pedals. Today while playing, I noticed a sporadic fizzing and drop in gain when playing the lead channel on the amp. This occurred on all three guitars I own, so it might not be a case of bad soldering on the input jacks. This is the first time that this has happened since I bought the amp.

Any ideas as to whether or not the tubes need replacing? Any way you can tell by looking that the tubes need changing out?
Jackson PDX Demmelition w/ EMG 81/85
Vintage Lemon Drop w/ Seymour Duncan JB/Jazz
Dean Z Bubinga w/ Seymour Duncan Blackouts

Blackstar HT-5 combo
#3
Quote by Buck's Student
It could be your bias is set too high or cold.


Forgive me for being dumb, but how would I check this?
Jackson PDX Demmelition w/ EMG 81/85
Vintage Lemon Drop w/ Seymour Duncan JB/Jazz
Dean Z Bubinga w/ Seymour Duncan Blackouts

Blackstar HT-5 combo
#4
Quote by Rargh
Forgive me for being dumb, but how would I check this?

Depending on your amp... If you have no experience, you're better off having a tech looking at it.

I taught myself how to bias my Hot Rod Deluxe, which is easier than some amps. If you're not willing to take it to a shop, then you can look up how to bias your specific model.

Obviously, you're going to have to be very, very careful, because if you touch the wrong wire or something, you're dead meat. Keep one hand in your back pocket, or on something that isn't grounded (Like a rubber inflatable mattress in my case), and use a rubber glove if you can. Once you take off the back part of the amp, you look for a knob above your tubes, which will vary from amp to amp. You take a flathead screw driver, with the amp turned on and the volume off, turn it into the direct center. Once you do, I would turn it both ways for good measure. Turn the volume up as you adjust this knob, and you will notice more noise as you turn to the right, which is hotter, and less on the left, which is colder. A hot bias will be noisier, the tubes will die faster, but the tone is "hotter" and breaks up quicker. If you like a mellower sound, and in your case it may be better anyway, you should turn it left so there is less noise and the tubes run cooler.

This is a crackerjack approach, but it serves me well. Obviously, I'm not an expert, but this is the advice I use.
#5
pull everything you can out of the signal chain so that you have the guitar going into the amp directly with 1 cable (this eliminates the chance of it being a battery issue). if the problem persists, contact blackstar and explain the situation. most amp manufacturers are pretty much aware of common issues with their amps, and more importantly, they tend to know how to solve the issues. let them know whats up and see how they respond.

this should be your plan of attack given that you aren't particularly knowledgeable (I know what im doing, and I still email the manufacturer first) about the workings of your amp. the manufacturer can also advise as to whether something can be fixed at home, or whether they recommend that you take it to a pro.