DC-3 Speaker question

[plumptone]

Is there any easy way to tell whether my speaker is bad? It's the original V30, and lately it's been sounding real harsh. I'd describe the sound as being similar to what happens when you have a bad cable, although I have eliminated the cables as contributing to the problem. Also sometimes kind of sounds like a ghost note. The problem is most apparent when I'm overdriving the amp, and only seems to occur at select frequencies. What's interesting is that when I use an external cab, the problem stops - that's partially why I'm thinking it could be the speaker, although I suppose it could also be due to the fact that the amp itself isn't being subjected to any vibration when I do that.

My alternate theory is that my tubes are bad. It's been over a year, and I'm due anyway. I have ordered a new set of JJs. I'm hoping that takes care of the problem. But as a general proposition, is there a way to tell when the speaker's dying? Any help (as usual) greatly appreciated.

 

[Monsta-Tone]

You can try a couple of other things too:

1. Take the 1/4" connector apart that is wired to your speaker. Check the solder connections in it.

2. Try plugging your V30 into one of the other Speaker Jacks.

3. Look at the connections on the back of the speaker, see if the solder connections are bad, or if it has terminals, sometimes they become loose after a while. You can fix loose terminals by pulling them from the speaker and crimping them SLIGHTLY with needle nose pliers. Then put them back on. Essentially, you are tightening the connection.

 

[wolfgang6505]

Put a multi meter on her, if it comes up open it's bad news

 

[Monsta-Tone]

Another thing you could try is tapping on the top of the amp while using the Internal Speaker.

This same thing happened to me yesterday when I was playing my Fender 75. I thought it was the speaker connections.

It ended up being a bad Phase Inverter tube (the one farthest away from your Amp's Input jack on the DC-3) and it's Tube Socket was loose.

I was able to find the problem by tugging on the speaker connection & speaker cord, and tapping (GENTLY) on each tube 1 at a time.



Hope this helps.

 

[twangbanger]

Sounds like you need to look at the tubes first.

Phase Inverter, V1 AX7 or the power tubes.

 

[plumptone]

Thanks for all the info guys. I now know what the problem is. I ordered a whole new set of tubes from Bob at Eurotubes, and put then in on Saturday. (Remarkable service at Eurotubes, by the way - the new tubes arrived in 2 days!)

Anyway, the new tubes sound fantastic, but I was really disappointed when after about 15 minutes, and once I had the amp thumping at significant volume, the problem remanifested itself. Quite by accident, while it was happening I let a G on the low E string ring out (this is when it seems most noticeable) and was playing with the EQ sliders. I lowered the 80K slider, and the crackling stopped. I then raised it back up, and it was still OK. I hit the G again, and again the noise started. If I just push on the 80K slider knob, the problem stops. I must have a bad slider, and the vibration is rattling it loose. For now I can deal with this by taping down the slider, but it looks like I'll have to have the sliders looked at.

Funny thing is that I was having problems with this slider crapping out on me before, but after a good cleaning it seemed to be OK. I guess the slider was actually bad the whole time - not dirty. I hope this is not an expensive fix when I get to it.

 

[Monsta-Tone]

Radio Shack has a Contact Cleaner with a lubricant in it that might work better at stopping it from happening again.

I clean all of my noisy parts out with CRC Contact Cleaner a few times, and then use the Radio Shach stuff, moving the part back & forth between squirts. It's $10 a can (small can), so I try to conserve a little bit.

This combination seems to work much better than Contact Cleaner alone.

I've also found that if you return the pot or slider back to the same spot each time you spray it in there, you vreate a blind spot of sorts, where the cleaner doesn't do it's job as well.

Hope this helps, and saves you a repair bill.

 

[Monsta-Tone]

Oops, double Post.

 

[plumptone]

Monsta - is this the stuff you are talking about?

[/url]http://www.radioshack.com/product/index.jsp?productId=2103700&cp=&kw=contact+cleaner&parentPage=search

 

[Monsta-Tone]

That's the one. It's a bit spendy, so I use it sparingly.

Also, be careful when shooting it into the slider, it seems to have much more pressure than the other brands and will spray back at you if you're not careful. Hurts like a mutha when you get it in your eyes.

 

[plumptone]

Thanks - I'dd do this later today and let you know the results. I really hope this does the trick.

 

[plumptone]

Well then. I sprayed in the contact cleaner (which did a superb job lubricating and cleaning the EQ slider - thanks for that tip Moster), but at rehearsal I'm experiencing the same problem, which only means one thing: repair time. I hope this isn't an expensive fix, and more imorptantly I hope they can do it fast. I have gigs this weekend, so in all likelihood I won't get it done this week. Next week I have recording time booked, so I'll try and get it done before that, although frankly, the duct tape holding it in place does seem to do the job.

I would attempt this myself, but I won't have the time. Doe anyone know whether these eq sliders are a special order from MB, or are they something that can be picked up generic?

 

[Monsta-Tone]

It might be just loose solder connections on the back of the slider.

If not, you can get them fro MB. You might order one, and then if it is only loose connections, you have a spare.


Sorry the contact cleaner/lube didn't work. I try to get all of my customers to try simple things before they bring their amps to me. Tube swapping, etc. It saves them time and money if it's a simple fix. This one honest, upfront act has earned me more repeat business than I can handle.