JBL SR4715a questions

[djerickson]

Picked up a another barn find yesterday... two JBL SR4715a speakers. One seemed to work and the other had an issue. When I tore them apart I found them loaded with 2235h speakers. The two working speakers had accordion type edges and leads attached to the cone that were each about an inch long. The two non working speakers had 2235h magnets but the cones were different. One had the same edge but very short leads attached to the cone (1/8 in.) and the other had a foam suspension edge which was totally dry rotted. Did they ever sell the 4715 equipped with these 2235's or did somebody swap out the 2226's and drop these in? The cabinets are in great shape and I'd love to get these going. Will the drivers I have work in this cabinet if I get the two speakers reconed? The 2235's are only rated at 300 watts which is half what the 2226's can handle. Looking for some advise...thanks!

[Keyrick]

Have a look.

http://www.jblproservice.com/pdf/SR-Series/SR4715N.pdf

[sibyrnes]

I hope you got them cheap! You are correct in that they should have 2226 speakers. I have a pair of them that I occasionally use as mid/bass in a four way system. It looks like somebody sold the original speakers in your cabs and put in some butchered up replacements. I don't know if it's worth it to get the 2235's reconed-I'm not familiar with that speaker. If the cabs are in really good shape and you could get a great deal on some 2226's for them, you might come out OK on the deal.

[agedhorse]

Ok, looks like you got an interesting combination of speakers there.

First of all, there were some subs that used the 2235 drivers, they were some older cinema products, same time frame as those that used the 2245 drivers which were also foam surround. I serviced JBL cinema products for many years... up until Regal bought the chain that I did work for. All ~300 screens gone almost overnight after 10 years of service work. Oh well, big fish eat little fish, burp and fart loudly

I reconed every 2245 that came through my shop as a 2240, because the foam just wouldn't hold up in commercial environments as well as the deterioration due to environmental contaminants. The metalwork is identical.

Now I am going from memory here but I believe the 2235 and 2225 (the precursor to the 2226) used the same metalwork, and the 2225 recone kit can be used in the same way as the 2240 updated the 2245. I also do not believe the 2226 kit will work because the gap thickness is different as well as different metalwork.

If I was looking at reconing, I would investigate by reconing to 2225's. Not as high powered as the 2226 but it's the only practical option other than replacing with 2226's, but it's not a great cabinet anyway so investing a bunch of money would not be wise IMO. I have not checked my JBL parts compatability paperwork, but I think this is the most practical option.

[djerickson]

Thanks Aged! That explains the different cone suspension in the same speaker model. If I go the 2225 recone route than my rated power would be 300 watts per driver as opposed to 600 (with the 2226) is that correct? The speaker with the foam surround is still working....could a guy get away with just replacing the surround on that speaker as opposed to a recone? Sounds like a good box to get working and move along.

[agedhorse]

Originally Posted by djerickson

Thanks Aged! That explains the different cone suspension in the same speaker model. If I go the 2225 recone route than my rated power would be 300 watts per driver as opposed to 600 (with the 2226) is that correct? The speaker with the foam surround is still working....could a guy get away with just replacing the surround on that speaker as opposed to a recone? Sounds like a good box to get working and move along.

The sensitivity of the 2235 is lower because of the cone mass and suspension, so it's also not a great match (IF) for high powered use.

I would never rate the 2226 for 600 watts in that application... maybe 400 or so unless you use a steep HPF around 45Hz. The suspension components can not handle the low frequencies at the same levels as at higher frequencies. I think 300 watts per driver is ok for the 2225, with a 24dB/octave BW HPF set at around 42-45Hz

Do not replace the surround, there may be significant damage and shorted turns in the voice coil due to loss of alignment. I know we do not warranty this kind of repair, and if there are shorted turns it could damage the amplifier as well.