Started 2 years ago by oooliver22
Topic Rating:
Hi All,
my AC4TV has the tone that doesn't work anymore, no sound variation when moving it from the left to the right. Volume is ok.
My web dealer told me he can't repare it and can't change it as he doesn't have AC4TV anymore...
Does someone know what could be the issue and how to solve it?
Many thanks.
olivier
Posted 2 years ago
do you think I just need to change the preamp tube?
Some user say it could be sufficient, no need to change the "master" one
is the preamp a 12AX7, and which brand?
Sorry for that questions but I would have it as it was originally.
Posted 2 years ago
I would change both.
There are 2 tubes: EL84 poweramp tube and 12AX7 preamp tube.
I wouldn't get hung up about replacing with the same tubes as Vox use - you can do, & Vox technical support should be able to tell you exactly what tubes are 'stock' - but there are better makes of tubes to try. Make is down to personal preference e.g. I've heard good things about JJ tubes.
Posted 2 years ago
sorry...
do you know how to check if the preamp tube is dead or not, should I have a light when the amp is pluged?
How can I test that the Tone knob (the electronic behind) is working...?
I heard also that tubes Tung sol could be fine, but don't know
Thanks again
Posted 2 years ago
Tung sol are good tubes - as I said, it's all down to taste. You can't tell the condition of a tube just by how bright or dull it is. If your tone has 'gone', it's almost certainly retube time. Sorry, don't understand your queastion re Tone knob.
Posted 2 years ago
What's the relationship between the valves and the tone knob not working?
Posted 2 years ago
Although this little amp sounds great, the cost of the parts, speaker and transformers aside, show that it is really in danger of having resistors fail, which is what happened to mine 2 weeks after i bought it, rather than have the local dealer respond to me as yours has , I decided to face my fears of electricity, did some research looked at the amp and replaced every single resistor, ceramic cap and electrolytic cap with hifi/ boutique quality components, total cost minus screw-ups, maybe $100, same price as paying a tech to look at it. It is now a smoking hot blues amp which will be very reliable, the sound is near identical except that it maybe has a slightly smoother sound but sure has the grind and crunch when pushed( if you want the same sound use the original ceramic caps and coupling capacitors) It really now is one of my favourite amps ever and that is due to VOX's design, it will go down as a classic i think
Posted 2 years ago
I played through this amp for a while, although I haven't bought one (yet). What I noticed is that the tone knob doesn't really change anything noticeably when you have the amp set CLEAN. Drive the amp harder, it will have a much greater effect. That said, I love the sound of this amp clean anyway :-)
Posted 2 years ago
When I was trying out the AC4TVH, the tone knob worked perfectly as expected, clean or dirty.
Posted 2 years ago
i keep seeing threads about the tone knob not doing much on other forums.mine works great clean or dirty mainly cutting the treble
Posted 2 years ago
I have to admit that any changes my tone control makes is minimal, I don't really tend to bother with it and leave in the the mid position and do any tone changes on the guitar. And it's not something that has changed over time, I've had it for a little over a year now and the tone control (or lack of it) has never changed. Having said that I don't see it a issue and I'm really pleased with the amp.
Posted 2 years ago
My tone knob does very little, I leave it at 12 o'clock mostly because above that I get some hiss.
Posted 2 years ago
Really odd - as I mentioned earlier I found the tone knob quite responsive on the loan AC4TVH I had. Just a thought, & probably not, but could there be a slight difference as to the tone pots used in the combo's vs the heads?
Posted 2 years ago
If you are new to tubes and want to learn check out www.eurotubes.com. Tons of information on different tubes and brands. Really cool company. And for all vox lovers check out North Coast Music.
Posted 2 years ago
i thought this had happened to mine. it doesn't seem as obvious with some guitars but still works...
Posted 2 years ago
Same problem here, the tone knob doesnt work anymore, I was trying to get a darker tone in my AC4TVH but there wasnt any change, has anyone solved this problem?, Is the tube replacement enough to solve it? i hope someone can help me, i really like this litle amp
Posted 1 year ago
A bad pot of disconnected / faulty tone capacitor sound like the culprit rather than the tubes.
Posted 1 year ago
I opened the amp head, I saw three capacitors near the tone knob, C3 C4 and C5, do you kwow wich one could be the culprit? I dont want to make a mistake since I dont kwow anything about electronics
Posted 1 year ago
C3, C4 and VR1 make up the tone stack. If the volume is up high the tone control will have less effect, try turning the volume down to about 1/4 and see if you can hear it working.
The tone control is very simple on these amps and works by allowing some frequencies to by-pass the volume control. If the volume control is up high then the tone control has less effect as there is less resistance for the signal to by-pass.
Posted 1 year ago
