Yamaha Tweeter Horn Diaphragm Question

[kenmcculloch]

I bought a Yamaha S2115H II stage monitor at an estate sale and the tweeter horn has an open diaphragm (no back plate). The 2" diaphragm (rounded side out) is visible from the back. It looks like someone removed the back plate/cover.

I assume the back plate should be installed. Should I mod a back plate/cover with a little foam rubber lining and screw down to the three screw holes that are present. The horn has a 3/4" throat opening. Don't have any photos yet but here's a link to a site that sells the diaphragms that shows what you see when you look at the back of the driver. Am I missing something????

Also would an Eminence Legend 15 B 15" woofer work in this setup to replace the 15" Yamaha with a frozen vc? Or shold is used the B 15 as a straight sub in a JBL cabinet I got at the estate sale? Thanks.

http://www.speakerrepair.com/mm5/merchant.mvc?Screen=PROD&Product_Code=10-390&Category_Code=

[billfitzmaurice]

I bought a Yamaha S2115H II stage monitor at an estate sale and the tweeter horn has an open diaphragm (no back plate). The 2" diaphragm (rounded side out) is visible from the back. It looks like someone removed the back plate/cover. That cover also contained the magnet/motor, so the driver is toast.



Also would an Eminence Legend 15 B 15" woofer work in this setup to replace the 15" Yamaha with a frozen vc?You need to model the cab/driver combination to find that out.

[kenmcculloch]

Thanks Bill. Here's two pics to show what I've got. Here is what I've got. The dome is behind the magnet facing backwards???

http://img.photobucket.com/albums/v671/longdrive03/026.jpg

http://img.photobucket.com/albums/v671/longdrive03/028.jpg

[killersoundz]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-444

http://www.parts-express.com/images/item_large/290-444_L.jpg

Yamaha has been using these for a while, well their own OEM version that has "yamaha" stamped on that little plastic plate you're missing. Your cab is older so I don't think that is the exact replacement compression driver but it is the closest.

If it works without the back plate....hey why not? Aside from the obvious downfalls... The diaphragm looks good, go ahead and rig something up on there, I would probably just use a little piece of scrap plywood and secure it in the holes with some foam gasket material around it. No prob.

The Eminence Beta speakers are the equivalent to what you'll typically see in a yamaha as well..

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-410

[kenmcculloch]

Thanks. Think I'll build the back plate and try it out. I just tested the driver and it works so what the heck. I just repainted the cabinet and will probably recap the xover and then sell this thing. I've got some Klipsch drivers that I would use but I'd have to drill the horn flange to attach the driver. I'll post photos later.

[billfitzmaurice]

Thanks Bill. Here's two pics to show what I've got. Here is what I've got. The dome is behind the magnet facing backwards???

http://img.photobucket.com/albums/v671/longdrive03/026.jpg
OK, the magnet is obviously there so that's OK. The dome is inverted, which may be OK. To be sure pull the diaphragm and see if the phase plug is also inverted. You can fashion a replacement back cover from a piece of sheet ABS or Lexan, damp it with felt to prevent reflections back to the dome.

[kenmcculloch]

Thanks Bill. I'll try that and report back. BTW would the Eminence Legend B15 work in your 24 or 30 inch wide subs that are 36 x 36?? I've got one and a buddy is redoing his hunting cabin and needs some serious bass!!!

[killersoundz]

OK, the magnet is obviously there so that's OK. The dome is inverted, which may be OK. To be sure pull the diaphragm and see if the phase plug is also inverted. You can fashion a replacement back cover from a piece of sheet ABS or Lexan, damp it with felt to prevent reflections back to the dome.

Bill if I recall correctly on the last few Eminence compression drivers I used, when I pulled the back cover off and took a sneak peak I think the diaphragms were the same way.

[billfitzmaurice]

would the Eminence Legend B15 work in your 24 or 30 inch wide subs that are 36 x 36?? I've got one and a buddy is redoing his hunting cabin and needs some serious bass!!!B15 would work in the T48 cab, but that has pro-sound response. Good for music, not for HT, which goes an octave lower. So it depends on the application.

[kenmcculloch]

Got the diaphragm out and the phase plug is pointing the same direction as the diaphragm. Will make the back plate and line with felt and put er back together and see what happens. Thanks.

[killersoundz]

Got the diaphragm out and the phase plug is pointing the same direction as the diaphragm. Will make the back plate and line with felt and put er back together and see what happens. Thanks.

Good news. Yeah you definitely want a back plate on there. think about the pressure from the woofer distorting the sound of the CD with an open diaphragm. Whoever took it off.......well they aren't the brightest!