Deluxe Reverb Stock Speaker Trouble

[earache]

Has anyone ever encountered this - a speaker that only works sometimes? I thought a speaker is either blown or it isn't. The speaker in my recently purchased 73 SF DR has this problem - it seems to work again for a while after I smack the magnet in the back, but then stops after a couple crackles. I've checked the solder connections at the speaker and at the 1/4" jack and they're all OK.

I have plugged an external cab with a single 12" speaker in as a replacement and the amp works fine so I believe that it is the stock speaker.

By the way the external speaker I've used sounds great but it's a 16 ohm Celestion. Can I use it as a permanent replacement or will this cause too much strain on the amp?

[52 Bill]

Has anyone ever encountered this - a speaker that only works sometimes? I thought a speaker is either blown or it isn't.

There are a few other connections that can be bad as well, like where the voice coil connects to the tinsel leads and where the tinsel leads solder to the terminals. The tinsel leads themselves can fray and break.

[earache]

Sticky Voicecoil?

Is it possible for the voice coil to stick, and if so is there a way to diagnose that problem?

[52 Bill]

The next time it happens look at the cone and check to see if the cone is not resting in a normal position. When you hit the magnet does the cone pop free?

You could try gently pressing on the cone, both directions in and out, and see if the coil former hangs up on the magnet.

[Enzo]

If you think the reason it stops making sound is that the voice coil sticks, I have to doubt it. if it were able to stick solid, it would be rubbing and scraping the whole time while it WAS working.

I too must suggest your tinsel wires are broken. The ends sometimes touch.

[Bruce / Mission Amps]

That is interesting.
I've had three "problem amps" over the last few years where either myself and other techs here in Denver could not duplicate the problem or fix it... all three of them ended up being an intermittent tinsel lead or unviewable fractured wire at the voice coil.
Until those three amps got sent out to be played for a while at loud volumes, the stupid things would work perfectly until suddenly at an inopportune moment, the speaker would go open... and some times flash a power tube too.

[earache]

In order to complete this thread for posterity - reconing the speaker (and so having the leads replaced) has cured the problem with the speaker.
Thanks to all who chimed in with their help!