Replacing midrange speaker in Acme B-4

[PaulYeah]

I've blown the midrange speaker in my Acme Low B-4. Is there anything I need to know before I take it in to have it repaired? Is there a specific speaker model I need to ask for or would an "off the shelf" speaker suffice?

Thanks for the help!
Paul

[wcriley]

Are you sure it's the driver and not the little light bulb that serves as a fuse for the mid driver?

Best to contact Andy Lewis for a replacement driver, if that's what you need.

[AMJBASS]

I thought I had blown mine in my B2 when it was crackling and hissing. I called Andy, and he said that most of the time its the light bulb that protects the mid and high drivers just wearing out. The bulb can be bought anywhere(its a car brake light), and it is very inexpensive. I would try replacing that first. I replaced mine and it sounds as good as new.

[PaulYeah]

Here's a pic of what I've done. I think I was playing mp3s off of my laptop, at apparently too high a volume.

[billfitzmaurice]

Originally Posted by PaulYeah

Here's a pic of what I've done. I think I was playing mp3s off of my laptop, at apparently too high a volume.

That sort of damage can only be caused by something hitting the driver dome.

[PaulYeah]

Thanks, Bill. I think I know how it happened. My son is very curious and was probably poking at it with a screwdriver or something.

So what's the next step? Do I need to order a new mid driver from Acme?

[gregoire1]

Originally Posted by PaulYeah

Here's a pic of what I've done. I think I was playing mp3s off of my laptop, at apparently too high a volume.

You are lucky, toddler damage usually affects all the drivers in a cab.

[rpsands]

Ordering a new one from Acme is probably the best bet for getting a good sound.

I can't think of a lot of 5" woofers out there that would work. beyma's 5g40ND maybe, or Faitals 5, but I have no idea how they would sound.

[Mo'Phat]

If all your kid did was push in the dust cap, but the speaker is fine...then just leave it the way it is. The dust cap is only there to cover the hole on the cone. You can pop out the dent yourself (sometimes) with scotch tape and a string: tape the string to the cone and gently pull the dent out.

Another way is to bend the tip of a needle or T-pin 90degrees, poke it through the cone and work the dent out with the bent tip.

[caveat: the above are home-brew remedies and most likely NOT recommended by speaker repair professionals...just suggestions]

Or you can just call Andy and buy a new speaker directly from him, probably.

[lbwdog]

Doesn't look like the cone was punctured. You may be able to pull the dust cap out and keep using it.

[PaulYeah]

Awesome, I'll try popping out the dent.

I do have the scratchy sound that might indicate the bulb is burned out. What's the best way to get to the bulb?

[greenboy]

Originally Posted by rpsands

Ordering a new one from Acme is probably the best bet for getting a good sound.

Since the crossover is designed around the driver Andy used, it's also smart for impedance/load reasons. There were a few amps that couldn't deal with Acmes as it was.

[billfitzmaurice]

Originally Posted by PaulYeah

Awesome, I'll try popping out the dent.

I do have the scratchy sound that might indicate the bulb is burned out. What's the best way to get to the bulb?

If the bulb is burned out you don't get any output. Typically they're soldered in place on the crossover board.

[BassmanPaul]

These are mounted on the crossover PCB using a socket. To get at the lamp you have to remove a driver. On my B2, I had to remove the right hand driver. For the B4 I would guess to top right one should give you access. Slight push in and twist to remove it.

[PaulYeah]

I'm trying to remove the driver, and if feels like it's glued in or something. Or maybe I just don't have the right technique. I'm gently pushing in on the edge, and trying to twist, but it's not giving at all. I have had the drivers replaced before with Acme drivers at a local repair shop.

[BassmanPaul]

Twist was meant for the lamp not the driver .

You might have to gently pry the driver up with a small pry bar or flat head screwdriver. Be careful not to slip - it's all to easy to do so.

[rpsands]

uh, screws?

[AMJBASS]

Not sure if you got the driver out or not... there is a gasket under the driver that sticks a bit to the baffle. I had to pry mine out. When the bulb starts to go the tweeter and mid driver still function, but they crackle. Fixing the dust cap shouldn't be too hard.