Amp Tech Thread / Ask a tech Q

[VOLVO)))]

Same size, give or take. I assume they are the same part, diff outlet.

[aowron]

Just set my pedal board up again after not being used for some time, and everything looks good until turning on a pedal (any pedal), which results in the amp going silent. The amplifier is a blackstar HT1 amp and the power supply is a one of those power bricks (10 plugs or so).

I have tried individual pedals, and I'm still getting this. Also, the pedals indicate that they are getting power as supposed to (it is by the way also possible to replace a fuse in the power supply).

Any idea what could be causing this?

[VOLVO)))]

You're telling me it does this with any pedal powered by the brick, or any pedal? Eliminate all possible factors. Make sure it isn't the amp, first, so we can start eliminating shit on the board.

[aowron]

The amp works when the pedals are in bypass, none of the pedals work when connected to the brick, and the fuse in the brick is fine. Gonna test a few different combination of cables before starting to test the pedals with batteries.silent when turning on pedalsilent when turning on pedal

[aowron]

The amp works when the pedals are in bypass, none of the pedals work when connected to the brick, and the fuse in the brick is fine. Gonna test a few different combination of cables before starting to test the pedals with batteries.silent when turning on pedalsilent when turning on pedal

Ok, found the cause: turns out it was one of my cables (of course the one I never tested because of "hey, it's a planet waves cable that looks like new, that fucker can't be broken"). Kind of a weird problem though; any idea why that happens?

Edit: Eherm... Turns out I put the cables in the wrong in/outputs on the Pharaoh... *cough* I mean, checking the most obvious reason to why it wouldn't work first would really stupid, now wouldn't it? (notice the irony; yes, irony never work on teh internets)

Well, thanks for the help anyway!

[Dr. Skeeter]

What's the easiest way to split the signal between a guitar head/cab and a bass combo amp at the same damn time?

[moose23]

What's the easiest way to split the signal between a guitar head/cab and a bass combo amp at the same damn time?

Have you got a Boss Tu2 tuner?

[dunwichamps]

a y cable is the easiest way but probably results in ground loop hum. One signal generally needs to be transformer isolated from the other to reduce the problems of ground loop hum

[RAGER]

I've been using a Radial Big Shot for quite a while.  Like Dunwich said, it has an iso transformer among other features.  They're about 70 bucks.

[Mr. Foxen]

Line out on Sansamp or boss TU2 are pretty standard. The super ahrd on and thus most clones have two outs, the buffer sorts impedance issues arising from connecting two things.

[Dr. Skeeter]

Seeing as i'm a drummer i'm like wtf right now, but it sounds like we're about to get a boss TU2 tuner. I've heard that before anyways. Thanks guys.

[MichaelZodiac]

Speaker malfunction question:

On the last rehearsal, a speaker from a 210 cab started to break up really really soon, it sounded like AIDS so we unhooked the cab from the amp and unscrewed the grill cloth roster (it's one of those Peavey cabs with silver colored strips on the side), the speaker itself looked fine, the cone isn't torn so my question is: what could it be? Fixable or just get a new speaker? I didn't unhook the speaker itself because it didn't seem to budge, even when I unscrewed it..

[Pissy]

Speaker malfunction question:

On the last rehearsal, a speaker from a 210 cab started to break up really really soon, it sounded like AIDS so we unhooked the cab from the amp and unscrewed the grill cloth roster (it's one of those Peavey cabs with silver colored strips on the side), the speaker itself looked fine, the cone isn't torn so my question is: what could it be? Fixable or just get a new speaker? I didn't unhook the speaker itself because it didn't seem to budge, even when I unscrewed it..

If you're positive it's not ripped, press on the cone and listen for rubbing sounds. Next take a volt meter and check the impedance. It should read slightly lower than the spec. Also when you hook the leads of the meter up to the speaker, you should hear a few pops of white noise.

Check really good for a rip though. Is the cone seated completely to the frame around the outside?  That's not a rip, but it will fart like my dog after eating my 2 year olds chili off the high chair.

[Pissy]

Here's my current dilemma.



I bought a group of pedals and this one has a fully disclosed issue. Fried components.
That fried resistor I've pulled off the board and measured 79k. The capacitor next to it was puffy and I pulled it as well. It measured 110mF, half of its spec (220mF).

This is part of the power supply circuit.

I don't trust my reading of that resistor, so without a schematic I'm left to guess at the true value. The capacitor is easy enough. So for the resistor... 100k?

[moose23]

What effect is it and what values are the three caps, two look like 22uF? Good chance it could be either a 100R current limiter if it's inline with the supply line or it could match the one beside it and be used as a voltage divider for a bias supply Vb.

[Pissy]

220uF caps. The resistor beside it (if I'm up to snuff on my resistor codes) is 330k. Red-red-black-gold.

[Pissy]

It's a tech 21 Boost DLA.

[Instant Dan]

I have been Having trouble with my 800.

Noticing radio static/crackle after I hit a note. Otherwise, it's dead silent.


It's not the guitars or any of the cables.

I am guessing it's either the tubes, dirty sockets, or the filter caps.

[Pissy]

Would a microphonic tube cause this?  Try lightly tapping a tube to see if any of them transmit the tap through the amp.

[RAGER]

Take the head off the cabinet and try it.  That should tell you if something's loose also.

[Instant Dan]

Tried the pre-amp tubes and that's not it.

What's the darnedest thing is that after ten-fifteen minutes of it being on, after I let it warm up for about ten-fifteen minutes, the crackle/static noise that happens after I hit a note dissappears.

[RAGER]

Sounds like a bad solder joint.  When the amp heats up the joint expands.  First thing I would do is give it the old chopstick test.

[Mr. Foxen]

+1 on being a bad joint. Chopstick might give a clue as to where, but I'd go and resolder pretty much everything, chances are it wasn't a great job to start with.

[Instant Dan]

I did the chopstick method last night and sure enough, it is the solder joint(s).

Looks like she is going to the shop next week. I guess more of a reason to buy another head or tube combo.

[RAGER]

Re-flow the joint if you found it.