Ampeg B-15R

72rick · Post by **72rick** » Mon Feb 05, 2007 6:30 am

It's an over-load/over-current protection circuit for your speaker.

It would probably be a good idea to have a replacement bulb on hand, but they should last a long time before that's an issue.

Ya, I just checked my B-15R manual and my B-15E manual and they both don't mention it.

rickaddict · Post by **rickaddict** » Mon Feb 05, 2007 7:00 am

Wow. The service here on the RickResource forum is way faster than the service at Ampeg!

So...I still don't get it, Garret! How is a light bulb an overload/circuit protector for a speaker?

Does it work just like a fuse, then?--If I'm getting no sound, I look at the light bulb...If the filament is burned out, then I replace the lightbulb and I should get sound again?!

So I don't expect the bulb to ever light up, then?!

I'm just a caveman. Your "modern" machinery confuses and frightens me!

jnbass · Post by **jnbass** » Mon Feb 05, 2007 7:55 am

there was a light bulb in the BOSE 901 speaker for that very purpose.

very enlightening...

thx1955 · Post by **thx1955** » Mon Feb 05, 2007 8:12 am

Hi Jeff,
You're spot on, the light bulb does indeed act as a fuse, and if the filament is burned out then it needs replaced.

The bulb may from time to time glow depending on volume and peaks in your volume, however I'd not expect it to remain on constantly.

jingle_jangle · Post by **jingle_jangle** » Mon Feb 05, 2007 8:18 am

Wow. They missed a BIG opportunity to add some "bling" factor by mounting it on the outside of the head!

72rick · Post by **72rick** » Mon Feb 05, 2007 8:28 am

Hey Jeff, Jared, Jim,

Ya, this is the first time I've seen this as well.

I don't know if this is a Tube-Amp thing, but a close friend who runs a Tube Guitar system suggested I look and see if it had a lightbulb in the Speaker cabinet.

Thanks again Jim.

rickaddict · Post by **rickaddict** » Mon Feb 05, 2007 8:51 am

Thanks guys. I don't think I would have ever figured that out on my own. I was feeling around to see if there was a switch for the light, or a battery compartment or something!

And yes Paul, that would have been cool if Ampeg would have thought up some way to see the lightbulb glow when the amp was pushed hard.

jps · Post by **jps** » Mon Feb 05, 2007 1:05 pm

The lightbulb is a fairly common thing with SWR speaker cabinets and probably other makers, too. It is for the tweeter only, as an overload protection.

johnallg · Post by **johnallg** » Mon Feb 05, 2007 4:42 pm

Jeff T. - the bulb is in series (your sound goes through the bulb then the tweeter) with the tweeter and protects it. Crank up the volume, crank up the treble, and watch the speaker cones glow in the main cab until the bulb blows.

Then go to an airfield that services smaller aircraft and buy a few 24V bulbs in that shape. I believe the part number is on the bulb. There was a thread all about this on the Ampeg forum when there was one. But that's a whole 'nuther discussion...

rickaddict · Post by **rickaddict** » Tue Feb 06, 2007 3:52 am

Thanks guys. That's interesting and kinda cool.

Now I won't be trying to figure out how to turn the light on (or why I'd need to light a speaker cabinet) anymore!

charlyg · Post by **charlyg** » Tue Feb 06, 2007 4:24 am

ON a side note, remember the old Shure Vocal Master? They strung the filaments for the tubes with the panel lights! In series! If you lost a panel light, you lost your pa!

atomic_punk · Post by **atomic_punk** » Tue Feb 06, 2007 5:02 am

Here is a B15N if anyone is looking for one...

http://detroit.craigslist.org/msg/273988020.html

rickaddict · Post by **rickaddict** » Tue Feb 06, 2007 5:36 am

Cool. But mine has leather handles, so its better.

And also, my volume goes up to... eleven!

johnallg · Post by **johnallg** » Tue Feb 06, 2007 3:43 pm

Comes with extra NOS Sylvania 6L6 tubes - second in sound only to NOS RCA tubes.

ratso · Post by **ratso** » Tue Feb 06, 2007 3:56 pm

Those old 60's B15's are absolutely fantastic sounding bass amps for small venues. The smooth, creamy tones can't be beat. The best part is they can be had for less than $1000!