[Jukebox-list] Rockola 426 Speakers

[James Alexander]

Hello Steve:
RE:  RO spkrs.
Many RockOla 60's-70's jukes used 5x7" oval shaped car stereo spkrs as mid-high frequency speakers. The 5 x 7" size has become less popular in car stereo circles and is generally replaced by either 4 x 6" or 6 x 9" oval speakers if you have the room.   In your juke, you don't have the space for the 6x9" size.  
There are 5 x7" 's still available.  You need to match to the efficiency of the speakers to that of the woofers (I assume you still have the RO original 12" speakers)    This is why you should not use spkr models that have weighted cones,or long-flex foam suspensions.   This type of spkr has reduced efficiency and is designed to obtain more low-bass response from a small-size spkr enclosure.     The spkr specification you need to pay attention to is called the EIA sensitivity rating or SPL (sound pressure level) rating, given in Db. This is the measured output of the spkr with a sine-wave tone input at 1watt audio level, measured at 1 meter away from the device.  
The 5 x 7" spkr for this application should have a 1W/1M rating on the order of 92 to 96 db.  It would be nice if you can find a co-axial (center mounted tweeter) model, which might offer brighter ultra-high freq response, but it is not critical. In contrast, you'll see that foam-suspension type spkrs have sensitivities in the low 80 db range---not good for this job. 
A 5 x 7" spkr choice that I've used for replacement comes from Parts Express                                          (web: www.partsexpress.com)  and is their sku # 267-780.  It is a Pyle PLX572 spkr.   Parts Express probably has a half-dozen other 5 x7" choices if you want to compare them.   The PLX572 is the best acoustic match of those given.   If you'd rather install smaller 4 x 6" spkrs instead, pay attention to matching the sensitivity rating.   Look at the spkr specs and match the numbers if you'd prefer to buy somewhere else.                                                                                                                                                           When installing the new spkrs, pay attention to the condition of the in-line freq. limiting caps. They may need replacement.  Also pay attention to spkr phasing. The +  - terminals of the spkrs of various manufacturers are wired to different standards. Phasing can be checked using a 9V battery.   Another viable choice is obtaining good original RO spkrs.  
Hope this addresses your question fully,
Jim Alexander.
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