MRII594A mounting holes

**A7fan** · April 21st, 2010, 10:33 PM

Just picked up this horn. I have a 288C driver I want to mount on the flange. Not going to happen with the way it's drilled. Do I need an adapter plate for this? Seems odd that Altec would make a horn with a 1 1/4" throat that a large format driver cannot be directly mounted. Thanks in advance for your input.

**Old Guy** · April 21st, 2010, 10:39 PM

I think the newer mantarays were 4 bolt instead of 3?

The old 3 bolt pattern has pretty much disappeared

Most 1.4 inch horns are now 4 bolt

the hole drawing is here...you could probably have a machine shop re-drill them

http://www.altecpro.com/pdfs/vintage...%20Drivers.pdf

**A7fan** · April 21st, 2010, 11:11 PM

Thanks Old Guy. I have a cut sheet from Great Plains. They still produce and sell the Mantaray horn. I did not know the newer drivers have four bolts. The Great Plains cut sheet shows a diver horn mounting bracket, (not available at this time). The horn does have the three bolt pattern, two holes counter sunk into the body, and one through the lip. I'm guessing that the adapter would fit over the driver bolts and the driver nuts would secure the adapter. Now if I'm reading the cut sheet right, the adapter should bolt to the horn. Will I need to place a gasket between the flange and adapter? Just trying to figure this critter out before I try and fab something up. Thanks again.

**A7fan** · April 21st, 2010, 11:17 PM

Thanks Old Guy. I have a cut sheet from Great Plains. They still produce and sell the Mantaray horn. I did not know the newer drivers have four bolts. The Great Plains cut sheet shows a diver horn mounting bracket, (not available at this time). The horn does have the three bolt pattern, two holes counter sunk into the body, and one through the lip. I'm guessing that the adapter would fit over the driver bolts and the driver nuts would secure the adapter. Now if I'm reading the cut sheet right, the adapter should bolt to the horn. Will I need to place a gasket between the flange and adapter? Just trying to figure this critter out before I try and fab something up. Thanks again.

**magnarc** · April 22nd, 2010, 01:30 AM

This thread goes into more detail.

http://www.hostboard.com/forums/alte...-mrii594a.html

I'm about to get some of these machined up.

**Altec Best** · April 22nd, 2010, 07:00 PM

The plate measures 7 1/2" x 7 1/2" and the gaskets are paper thin here's a picture Regards

**whitebroncoii** · April 23rd, 2010, 01:00 PM

Originally Posted by Altec Best

The plate measures 7 1/2" x 7 1/2" and the gaskets are paper thin here's a picture Regards

This is not an adapter plate for mounting a 3-stud Altec driver to a 4-hole horn. This is a simple mounting plate for suspending MRII horns. The MRII horn is very short and needed extra support on the driver end due to the weight of the driver. This plate gave the installer something to grab on to.

An adapter will need to have depth for bolt heads or hex heads to recess. The adapter would be bolted to the driver and four studs on the horn side would extend through the horn flange. I have a pair of custom aluminum adapters for bolting my 399s to small EV horns (1.4" throat).

**Altec Best** · April 24th, 2010, 03:04 PM

Originally Posted by whitebroncoii

This is not an adapter plate for mounting a 3-stud Altec driver to a 4-hole horn. This is a simple mounting plate for suspending MRII horns. The MRII horn is very short and needed extra support on the driver end due to the weight of the driver. This plate gave the installer something to grab on to.

An adapter will need to have depth for bolt heads or hex heads to recess. The adapter would be bolted to the driver and four studs on the horn side would extend through the horn flange. I have a pair of custom aluminum adapters for bolting my 399s to small EV horns (1.4" throat).

I thought he was just looking for the gaskets and plate my Bad.

**A7fan** · April 24th, 2010, 04:12 PM

Thanks for all your input. Had a friend who is into metal working fab one up Friday. He was in a hurry and got it wrong. He also used 1/16 plate steel, not good. I'll look for some aluminum plate this weekend and give it another shot Monday.

**Altec Best** · April 25th, 2010, 09:52 AM

Originally Posted by A7fan

Thanks for all your input. Had a friend who is into metal working fab one up Friday. He was in a hurry and got it wrong. He also used 1/16 plate steel, not good. I'll look for some aluminum plate this weekend and give it another shot Monday.

The original plates that I have shown are 1/8" thick steel plate.