Speaker Question

Eddie Malray · Post by **Eddie Malray** » 29 Dec 2004 8:07 am

Question: Are the speaker mounting hole patterns universial or do they vary from brand to brand? Thanks-----------Eddie

Donny Hinson · Post by **Donny Hinson** » 29 Dec 2004 8:35 am

Speakers usually have 8 mounting holes, which are equally spaced. Normally, they line up pretty well from brand to brand, but I have encountered cases where the holes will be on a slightly larger diameter for the same-sized speakers.

It's very important not to over-torque the speaker mounting bolts! High amounts of tightness can permanently warp the basket, especially if more than 4 screws or bolts are used to secure the speaker.

John Daugherty · Post by **John Daugherty** » 29 Dec 2004 9:10 am

Some speakers are designed to mount to the inside of the baffle board, while others mount to the outside.........JD

Dave Grafe · Post by **Dave Grafe** » 29 Dec 2004 1:35 pm

High amounts of tightness can permanently warp the basket, especially if more than 4 screws or bolts are used to secure the speaker

Good point about over-tightening, Donny, but actually, the warping factor is much GREATER if only four bolts are used - best to use all eight bolt holes and tighten them reasonably snug.

Also, most top-of-the-line (JBL, EV, BW) speakers are designed to mount on either side of the baffle provided that the appropriate gasket is used.

dg[This message was edited by Dave Grafe on 29 December 2004 at 01:37 PM.]

Stephen Gambrell · Post by **Stephen Gambrell** » 29 Dec 2004 7:38 pm

Dave, I'm not trying to start an argument here, but I've always been told that 4 bolts should be used, and not much more than finger tight. Reason being that if the baffle is warped, then pulling the frame down tight, especially with all eight bolts, will throw the frame out of line, and increase the voice coils chances of shorting out. Sound reasonable?

Donny Hinson · Post by **Donny Hinson** » 29 Dec 2004 9:25 pm

Took me a while to find it, but here's a quote from Harvey Gerst (he's the guy that designed the JBL "D" and "F" series speakers)...

Most people don't realize that even though 8 mounting holes were available, only using 4 is the recommended mounting. And you don't screw them down tight to the board - that warps the frame. You use 2 fingers to do the final tightening - the gasket will complete the seal. When you warp the frame by overtightening, the voice coil can go out of round and eventually drag and short out.

Les Pierce · Post by **Les Pierce** » 1 Jan 2005 12:18 am

I don't know...I remember the D130 and D140 JBL's, and I can't imagine warping that massive frame.

I have also found out that one man's two fingers may, or may not match the torque of another man's two fingers. (It would be better to provide a torque value in inch/pounds, at least).

There is a lot of vibration when a speaker is being used at stage volume, I think it would have to be tight. I would say if you are going to use the two finger rule, then as tight as you can get it with two fingers.

Les

Dave Grafe · Post by **Dave Grafe** » 1 Jan 2005 9:39 am

if the baffle is warped, then pulling the frame down tight, especially with all eight bolts, will throw the frame out of line

That's a very good point, actually, particularly with the pressed steel baskets. I have never had any problem with this issue, but I have used only JBL and TAD drivers since, well, dirt, and the baffles on my cabinets are 3/4" or better.

I tend to tighten them down all very snug (hand tight with a nut driver) against the gasket because of the abuse they receive from doing their job as well as the transport factor - I can't afford to have a speaker drop out of a cabinet at a high-profile gig, nosirree.

If you ever take a look at the low frequency drivers in pro touring rigs you will find that all eight holes are used and most of them SERIOUSLY tightened down. Those cabinets are generally more carefully constructed than your average guitar amps, though, and take a lot more abuse in the day-to-day.

Far be it from me to argue with Mr. Gest, however...

dg[This message was edited by Dave Grafe on 01 January 2005 at 09:45 AM.]

John Bechtel · Post by **John Bechtel** » 1 Jan 2005 9:42 am

My thougts are: If you're only going to tighten ‘finger-tight’, you may as well just hang the speaker on a hook! With my luck, a speaker would be long-gone before arriving at a venue! I always thought the Baffle-Board acted as a sounding-board for the speaker! Of course, again; I know next to nothing about electronics!

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Eddie Malray · Post by **Eddie Malray** » 10 Jan 2005 2:39 pm

Thanks guys for the info-------------Eddie