JBL sr4725 problems

[gottaJam]

Hello everyone, i am new to the board and very glad to find it!


Recently the Church I attend replaced all of their sound system. They had some older model JBLSR4725 speakers left over and gave them to me. The lows sound really good, but for some reason the horns aren't working on either one of them. I checked to make sure the wires were still good and tight. Everything looks good, but still no sound from either horns. I actually looked at the crossover and everything looked good on it, but could be something internally. I would appreciate any input. If it can't be fixed do you have any suggestions on crossovers that might fit the same place?

oh, the horn number is 2370a, horn driver is 2426h and the crossover number is 71935.

Thanks in advance for your help! Have a great day.

[4313B]

Check the DCR's and run test sweeps on the compression drivers.

http://www.jblproservice.com/pdf/SR-Series/SR4725.pdf

[Zilch]

Get those workin', and they're gonna rock the neighborhood!

[Single amp plugged into the "Full-range Input" jack?]

[pelly3s]

upgrading to the 4725X crossover is a good start. they are a good sounding box definately get loud.

[Mike Caldwell]

Hello
As was mentioned before directly check the 2426 drivers at least with a plain o'l ohm meter. The 2426H is 8 ohms and should read about 3.2 to 3.5 measured with a DC meter. The older SR series cabinets had trouble with intermittent crossovers due to vibration and the heating and cooling of the resistors on the crossover board. If the drivers check out OK look at the crossover for cold or cracked solder connections. If yours is the very early version with only the 1/4 inch input jacks thay may also be part of the problem. On those models they used a normaling style of jack that depending on the ones you pluged into would switch the cabinet from passive to bi-amp, sometimes the contacts in the jacks would loose their connection and cause the horns to go out. I have worked on and modified a few of the older JBL SR's and always found the crossovers and or input jacks to be the main problem. Let us know what you find.

Mike Caldwell

[gottaJam]

Thanks for all the replies. a little while ago when i got off of work, i put the meter across the 2426 drivers and had an infinite resistance. i have found one problem, but i would hate to replace the drivers and then they mess up again. maybe there is something wrong with the crossover causing improper output. i do have the 1/4 inch inputs like you mentioned with a choice of either full range, high pass, or low pass. what should be my next step? do i replace that whole piece with an updated input or just the horn, or both? if i have to replace any parts, i would appreciate some links to pricing information on new or used.

Thanks, you people rock

[JBL Dog]

Thanks for all the replies. a little while ago when i got off of work, i put the meter across the 2426 drivers and had an infinite resistance. i have found one problem, but i would hate to replace the drivers and then they mess up again. maybe there is something wrong with the crossover causing improper output. i do have the 1/4 inch inputs like you mentioned with a choice of either full range, high pass, or low pass. what should be my next step? do i replace that whole piece with an updated input or just the horn, or both? if i have to replace any parts, i would appreciate some links to pricing information on new or used.

Thanks, you people rock

Have you bypassed the crossovers and tried running the drivers full range? It won't hurt them if you do this for a very short period of time at a very low volume. You can also use an active crossover with the high frequency set above 600hz.

If the culprit is the diaphragm, aftermarket kits run $50+ on Ebay. If you wish to replace with an authentic titanium JBL kit, the part number is a D8R2425. Orange County sells the JBL kit for $136.00:

Diaphragms, Replacement Speaker Parts, Woofers, Tweeters, Repair Parts

I have a set of SR4725A's... they are definitely worth the investment to repair them.

Good Luck and welcome to the forum!

[Zilch]

Unless you know how to change out the diaphragms, take the drivers to your nearest JBL service center to have new ones installed:

http://www.jblproservice.com/service/louisiana.html

It's unlikely anything in the speakers blew them, but go easy at first after they're fixed to be sure, as suggested above. C4 is always in series with the 2426H, so even plugging a full-range source into the HF Biamp input would not do them in, unless it was REALLY loud.

If you want added assurance, take the complete systems in for service. Then, if they fail again, it'll be under the service warranty....