Dead silent speaker, no ohms

[nateflanigan]

Hey guys this problem is totally new to me.  I have a really nice 70's b15 cabinet that I use at home with a DIY B15.  I played through it as recently as last week with no problems.  Tonight I pulled it out into the kitchen for a bass lesson, went to turn on the amp, nothing but silence (and some egg on my face).  I just tested the amp through another cabinet, and verified that the amp speaker cable are fine.  I opened up the cabinet and I can't see any loose connections between the terminals and those little wires that touch the cone itself.  I'm getting no reading on my meter when I strap it across the terminals.  Any insights?  If this is something I can't fix myself I'd at least like to figure out whats going on.


Thanks!

[eleventeen]

" I just tested the amp through another cabinet, and verified that the amp speaker cable are fine.  I opened up the cabinet and I can't see any loose connections between the terminals and those little wires that touch the cone itself.  I'm getting no reading on my meter when I strap it across the terminals.  Any insights?  If this is something I can't fix myself I'd at least like to figure out whats going on."



If your ohmmeter, reading directly across the speaker terms mounted on the speaker frame reads "open" then either the speaker coil is open or, as you say, one of those braided ultra-flexible wires to the voice coil is broken, OR, the terminals themselves have some sort of corrosion on them that is "fooling" your meter. This is where I would start, and to be sure, I would gently scrape those terminals with a knife blade or rub them with a file or some sandpaper before touching the meter probes to them so that I knew I was getting good contact.

[Willabe]

You can also take a 9v battery and just touch the +/- to the speaker leads for just a second. Do NOT leave the battery connected to the speaker wires, speaker voice coils do not like DC.

If the speaker is good it make a low click/dumph sound that you will clearly hear as the speaker cone moves out/in or in/out. (Positive of battery to positive of speaker will throw/push the speaker cone forward.)


                    Brad   

[nateflanigan]

Just tried the battery trick, got nothing.  So does that indicate an open voice coil?  How fixable is this?  It was a fantastic speaker.

[eleventeen]

Offhand, yeah, open coil. You could try to kind of gently touch those flexible leads that go from the terminal to the voice coil with a pencil or a chopstick and see if they detach from the terminal strip. If they detach from the voice coil you have confirmed death. Sometimes they break, and if they break at the terminal, there's some chance you can resolder the end to the appropriate terminal. It's a delicate operation.

[PRR]

> a 9v battery ... Do NOT leave the battery connected to the speaker wires, speaker voice coils do not like DC.

A B-15 size speaker can absorb a 9V battery until the battery goes flat. "Most" guitar amp speakers can. Table-radio speakers may not like a 9V battery for more than a few seconds. 9V power-packs CAN hold power for hours and could cook the smaller geetar speakers in some seconds of steady DC.

But you don't hear anything except the Make and Break actions, so the goal is to tap the battery on-off-on listening for the clicks.

A 1.5V battery works good too, except you really need a battery holder to make connections. (The old screw-terminal #6 cell has gone obsolete.)

[nateflanigan]

Poking (gently) at the tinsel didn't reveal anything either.  Without really pulling on it, they seem firmly connected to both the terminals and speaker cone.  Maybe there's a break in one of the wires.  Fortunately I have local-ish access to a really great speaker tech.  But looking around there's lots of replacement options in the $100 range, not sure if it's worth repairing, I hate having that attitude.

[Willabe]

PRR, thanks for the information.

But looking around there's lots of replacement options in the $100 range, not sure if it's worth repairing

Depends on how much you like/love the sound of that speaker?


                Brad   

[terminalgs]

I recently had the same thing happen to a Celestion Alnico Blue. (!!!)   I have a quote that the repair will be about $100 (plus shipping).

[Ed_Chambley]

With a signal passing through the cable, push on the speaker from the front moving the speaker.  This will often make the coil connect intermittently.  That will give you your answer, but if you measured it and got no resistance, I assume it is time for a recone.


Most any good 15" speaker is worth a recone.  Check the prices.  It has to do with what speaker is is.  What magnet and what not.  If it is original to the cab, I would recone. 


I have done them myself and have had others  do the recone.  On the Celestion Blue, Orange County Speakers does a real good job and use British parts.  Last 2 I had done were about $75 each.

[6G6]

It sounds like it could be an open VC.
If you are open to options, the optional speaker for the B15 was the Altec-Lansing 421.
Great bass speaker!

[jojokeo]

With a signal passing through the cable, push on the speaker from the front moving the speaker.

Orange County Speakers does a real good job

I would never recommend pushing on a speaker cone unless I knew for a fact the speaker was blown, had a known rub, and/or was going in for service for sure anyway as it could guarantee that a re-cone would be needed. For troubleshooting to know for sure, then yep that would confirm it maybe? But this doesn't seem to be the case for Nate since the speaker worked the last time he turned the amp on. For the speaker to go on it's own and not while playing seems remote at best. I repaired a Line 6 amp about a year ago that had no sound which was tracked down to being a speaker issue. Same thing, no continuity. The interesting thing was that the tinsel actually was soldered to a small metal ring attached the cone like an eyelet. The small fine coil wire was attached here also. A quick low heat re-solder to the tinsel and the speaker (& amp) was back in business. It's the first time I've seen a speaker with something like this.

Another suggestion Nate could try is gently scrape the coil wires glued to the front of the cone exposing the bare wire where he could try for continuity there too. If okay, then lightly glue it back or use a dab of caulk. If not, then it doesn't matter anyway.

OC speaker has been in business for over 4 decades, I'm lucky to live about 15 minutes away. My first experience with them was about back that far when I blew out the 10's on my old BF Tremolux piggy back and have been going back ever since when needed.