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Electro-Voice Sentry 500

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Hello everyone,

I am (and have been trying for ages) to locate a schematic for this speaker's network (I have the factory spec sheet but it contains no specific details as for the network and wiring)

Since Bosch has taken EV over support is non-existent and just flat out rude - I've tried talking with them several times

Obviously, I own a pair, but I want a diagram primarily to see how the original design treated tweeter phase (wiring polarity)

I purchased these, lightly used, from a pro dealer back around 1990 and there is a GOOD chance they were monkeyed with - they sounded fantastic back then but not so much now (still good after the re-edge, but not like they were if memory serves) and I've never been 100% certain they were factory correct at any time

I've already done the switch the wires and see what happens, how does it sound dealio - results were inconclusive/not convinced 

I REALLY need an accurate diagram

Long story, but my pair is one I bought (almost new) back in the early '90s (like I already said), then made the mistake of selling around 2001, sought them out last year, actually found the guy after 15 plus years and bought them back 

While they were with the second owner they took a beating (cosmetic) but I digress

I had to do a re-foam on the woofer surrounds and a small compromise had to be made - again, long story - but the pro 12" EV woofer is fairly uncommon and is a hard surround to fit (but again, irrelevant to my quest!) 

So to the point, I'd really be EXTREMELY grateful to find a schematic for this system, first and foremost, as well as a secondary item - a source for the acoustic foam that EV used to dampen their tweeter diaphragms on their models with the "Direktor" horn loaded tweeters

 I'm not interested in the junk that outfits like Simply Speakers sells - it's too thick and comes with that old "not exact, but close enough, won't affect sound" - I'd like to find some correct material, or at least something honestly close/designed for the purpose - I realize that the possibility of actually finding genuine EV foam ain't going to happen, pipe dream, and it doesn't need to be

Right now, my original material is still intact thankfully, but if I ever have to service them I am sure it will disintegrate

(I'm not looking for the stuff they used as a "diffuser" around the tweeter, like what was on the Interface models and the Sentry 100, à la the JBL L100, rather the thin material they actual put on top of the dome à la Acoustic Research's mids (where they used the yellow glass type material)  The damping foam is fairly important on the EV tweeter as they can be EXTREMELY bright to the point of harshness without it

BUT THE ACOUSTIC FOAM IS A SECONDARY ISSUE - just thought I'd throw that out there while I was typing this story! ; - )

An accurate system schematic is my primary goal

Any help or leads would be well received

Thanks to all


This is what I'm working on and need the network schematic for; you can also see the foam in the center of the horn - it was probably about an 1/8 of an inch thick when new - on most vintage pro EVs it's missing (been removed due to rot):

Image result for ev sentry 500

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