Hello folks,
Just re-foamed Cerwin Vega R12's (1977 two-way loudspeaker) after many years of storage and one tweeter wasn't working. No hiss or crackle like it was blown, just zero sound.
Pulled both tweeters and swapped them into opposite cab's and the bad tweeter doesn't work in either cab, while the good tweeter works in both, so it's in the tweeter itself.
Got out DMM and tested across terminal leads on the good tweeter and got 8 ohms and it is indeed an 8 ohms tweeter. (Surprised it read 8 ohms as I read an 8 ohm tweeter reads closer to 5, but whatever... I got 8 full ohms from it.) Tested the bad tweeter and got no reading (0 ohms).
Read 0 ohms means either a "dead short" or "open voice coil" ... and wondering where I can go from here. I know nothing of electronics so please respond as if I am in training.
Is this tweeter just no good anymore? Can I try something to unstick the voice coil, if that's it... or open it and look for an obvious soldering break? Thanks!
Just re-foamed Cerwin Vega R12's (1977 two-way loudspeaker) after many years of storage and one tweeter wasn't working. No hiss or crackle like it was blown, just zero sound.
Pulled both tweeters and swapped them into opposite cab's and the bad tweeter doesn't work in either cab, while the good tweeter works in both, so it's in the tweeter itself.
Got out DMM and tested across terminal leads on the good tweeter and got 8 ohms and it is indeed an 8 ohms tweeter. (Surprised it read 8 ohms as I read an 8 ohm tweeter reads closer to 5, but whatever... I got 8 full ohms from it.) Tested the bad tweeter and got no reading (0 ohms).
Read 0 ohms means either a "dead short" or "open voice coil" ... and wondering where I can go from here. I know nothing of electronics so please respond as if I am in training.
Is this tweeter just no good anymore? Can I try something to unstick the voice coil, if that's it... or open it and look for an obvious soldering break? Thanks!
Hi,
A dead short is very unusual failure mode for a tweeter,
as it requires epic meltdown without it going open, and
AFAIK that simply never happens, I've never seen it or
heard of it in over 40 years of being involved in audio.
0 ohms does not mean an "open voice coil" that would
measure very high ohms, not a short. If a tweeter
measures 0 ohms I'd immediately look for a wiring
fault / failure as the only likely possible cause.
rgds, sreten.
FWIW read up on the "Econowave", that is the best
way to go with nice cabinets with a 12" bass/mid.
A dead short is very unusual failure mode for a tweeter,
as it requires epic meltdown without it going open, and
AFAIK that simply never happens, I've never seen it or
heard of it in over 40 years of being involved in audio.
0 ohms does not mean an "open voice coil" that would
measure very high ohms, not a short. If a tweeter
measures 0 ohms I'd immediately look for a wiring
fault / failure as the only likely possible cause.
rgds, sreten.
FWIW read up on the "Econowave", that is the best
way to go with nice cabinets with a 12" bass/mid.
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First, thanks to everyone for your feedback. I greatly appreciate it.
Again please excuse my ignorance, but I assume you mean a fault with the wiring on the tweeter itself, since the good tweeter worked in both cab's, and the bad tweeter is getting no reading on the DMM. (Just dbl-checking because I am so out of my element here.)
Like phivates mentioned, I noticed the varnish over the wire on the bad tweeter was 'a thin, skinny trail' and not as thick as the bead covering the wire on the good tweeter. I can't see an actual break in the varnish or wire anywhere. There was a spec of green corrosion (could only spot it with a magnifying glass) on one side of the voice coil at the base where the wire was running. I used a dental tool and toothbrush to clean it up gingerly, careful not to dig into the varnish or fine wire but it's so very thin (and already obviously broken somewhere) who knows if I made it worse. I would think there cannot be corrosion on varnish so the wire must be exposed there. <?> I did clean it up and could not see a break there or anywhere else, but I might need a microscope. I re-tested but still 0-ohms.
Hey thanks. I might need that. FTR these CV R12s are only 2-way loud speakers with a 12" woofer and 5-inch round, Dhorm tweeter (DH-10) with a 1-inch VC, 1.5 lb magnet, 2000 Hz xover, and 17,000 gauss... I didn't know what a Dhorm tweeter was (and am still not clear after reading about it). I will look at Econowave but I couldn't find anything to replace them the other night when looking.
However I did luck out... I found an original DH-10 pulled from an R12 just like mine on eBay.. so same exact tweeter meaning I would not have to replace both. He was asking $38 (incl shpg) but I offered $30 and he accepted. So it's on its way.
Meanwhile I AM going to continue to play with the one that isn't working as it looks perfect and I'd really like to find the problem. Even if I can't fix it, I'd just like to know where it failed. My guess is where that corrosion appeared.... maybe I need a better mag glass. Or younger eyes.
Also, these speakers were paired with a Technics SA-404 (50w) purchased at the same time in 1977, and I never abused the speakers. But they did sit in storage in a garage for the last 16 yrs or so. And here in So Cali the garage can get hot in summer. ?
Again please excuse my ignorance, but I assume you mean a fault with the wiring on the tweeter itself, since the good tweeter worked in both cab's, and the bad tweeter is getting no reading on the DMM. (Just dbl-checking because I am so out of my element here.)
Like phivates mentioned, I noticed the varnish over the wire on the bad tweeter was 'a thin, skinny trail' and not as thick as the bead covering the wire on the good tweeter. I can't see an actual break in the varnish or wire anywhere. There was a spec of green corrosion (could only spot it with a magnifying glass) on one side of the voice coil at the base where the wire was running. I used a dental tool and toothbrush to clean it up gingerly, careful not to dig into the varnish or fine wire but it's so very thin (and already obviously broken somewhere) who knows if I made it worse. I would think there cannot be corrosion on varnish so the wire must be exposed there. <?> I did clean it up and could not see a break there or anywhere else, but I might need a microscope.
I re-tested but still 0-ohms. Hey thanks. I might need that. FTR these CV R12s are only 2-way loud speakers with a 12" woofer and 5-inch round, Dhorm tweeter (DH-10) with a 1-inch VC, 1.5 lb magnet, 2000 Hz xover, and 17,000 gauss... I didn't know what a Dhorm tweeter was (and am still not clear after reading about it). I will look at Econowave but I couldn't find anything to replace them the other night when looking.
However I did luck out... I found an original DH-10 pulled from an R12 just like mine on eBay.. so same exact tweeter meaning I would not have to replace both. He was asking $38 (incl shpg) but I offered $30 and he accepted. So it's on its way.
Meanwhile I AM going to continue to play with the one that isn't working as it looks perfect and I'd really like to find the problem. Even if I can't fix it, I'd just like to know where it failed. My guess is where that corrosion appeared.... maybe I need a better mag glass. Or younger eyes.
Also, these speakers were paired with a Technics SA-404 (50w) purchased at the same time in 1977, and I never abused the speakers. But they did sit in storage in a garage for the last 16 yrs or so. And here in So Cali the garage can get hot in summer. ?
I went to parts express to look at them but am at a total loss when it comes to knowing which would be compatible spec-wise. Meanwhile it seems all of them would require a modification to the walnut cab. The original tweeter is round, 5-inch diam with four screw holes. View image: DH 10
But modifications aside, if you were to pick out a new replacement pair, which would you choose that wouldn't break the bank? (Like I saw a couple that were $189 ea which might as well be a gazillion dollars... can't dump that kind of cash into this.) I'd appreciate hearing opinions on replacements as it is very possible the tweeter I receive will die before long, or the one I have that's still working will die. So I might be replacing them soon anyway.
Thanks again to everyone for the help.
Hi,
New tweeters will require new crossovers, thus the Econowave,
as your best bet, unless you want to measure and get technical.
If a tweeter measures a short, 0 ohms, and has a metal chassis,
nearly all of the time the terminals are shorted together somehow.
Like I said I've never seen a melted tweeter that has gone short.
You sure it simply doesn't measure open, like most do ?
The other option to an Econowave, is a FAST, new simple 1st
order series x/o lower down to 3" FR (with a rear enclosure).
rgds, sreten.
Of course see how you get on with the replacement tweeter.
New tweeters will require new crossovers, thus the Econowave,
as your best bet, unless you want to measure and get technical.
If a tweeter measures a short, 0 ohms, and has a metal chassis,
nearly all of the time the terminals are shorted together somehow.
Like I said I've never seen a melted tweeter that has gone short.
You sure it simply doesn't measure open, like most do ?
The other option to an Econowave, is a FAST, new simple 1st
order series x/o lower down to 3" FR (with a rear enclosure).
rgds, sreten.
Of course see how you get on with the replacement tweeter.
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Nope! Sure don't! I don't even know how to take off the old x/o so would have to do a lot of reading and YouTube watching.
I am sure I could be reading or explaining what I see wrong. The meter simply doesn't change its reading when I touch leads to the bad tweeter terminals. So it says 0.L before, during and after. I interpreted that / expressed it as reading 0 ohms.
Thanks, but that's all Chinese to me, ("lower down to 3" FR" ? and with a rear enclosure... I don't know how that would fit in the cab unless it's supposed to sit on top or something). I guess I'll hope the new tweeter works. Unfortunately I don't have a great deal of time to devote to educating myself. But I will bookmark this thread and use it as a starting point if I need to do so in the future.
I am hoping more than ever that works out now.
The only electrical projects I've ever done include stuff like installing a 4-channel sound system in my vehicle, installing a DSL splitter on the home, ceiling fans, etc. (And of course setting up entertainment systems but that's not electrical... that's just plugging stuff in.) I have no soldering or wiring experience. If I have to go down this road it will be slow going. Thanks again for the insight.
"I am sure I could be reading or explaining what I see wrong. The meter simply doesn't change its reading when I touch leads to the bad tweeter terminals. So it says 0.L before, during and after. I interpreted that / expressed it as reading 0 ohms."
Every ohm meter I have ever seen will by default show infinite ohms when the leads are not connected together hence what you are seeing is an open voice coil not a shorted one. Try shorting both ohm meter leads together. That will show zero ohms.
Every ohm meter I have ever seen will by default show infinite ohms when the leads are not connected together hence what you are seeing is an open voice coil not a shorted one. Try shorting both ohm meter leads together. That will show zero ohms.
So I was expressing it wrong. It IS infinite ohms then. So is an open voice coil something that can be fixed?
Never mind. It's toast. I took my dental pick and made sure of it.
If one or the other tweeters goes out I will just get down the 1980 Cerwin Vega HED 1230's I have stored and take out their 5lb 12" woofers and put in the R12 7lb woofers and be done with it. All specs are the same for the woofers except the weight so they should play nice with the circuitry in the 3-way HEDs. And as far as I know the 1230 tweeters and mids are fine (so are the woofers for that matter). Then I'll store the HED woofers in case one of the R12 woofers fails and I have to swap them back.
Not a perfect solution since I want both sets of speakers but it would be fast and free. At a later date I could always find time to look into tweeters and x/o's and put the R12 woofers back in their cabs and add new tweeters... and restore the HEDs to normal.
But hopefully the replacement tweeter that's on its way and my original will work for awhile longer. Maybe a good while longer. Said the hopeful optimist. Thanks again, everyone.
If one or the other tweeters goes out I will just get down the 1980 Cerwin Vega HED 1230's I have stored and take out their 5lb 12" woofers and put in the R12 7lb woofers and be done with it. All specs are the same for the woofers except the weight so they should play nice with the circuitry in the 3-way HEDs. And as far as I know the 1230 tweeters and mids are fine (so are the woofers for that matter). Then I'll store the HED woofers in case one of the R12 woofers fails and I have to swap them back.
Not a perfect solution since I want both sets of speakers but it would be fast and free. At a later date I could always find time to look into tweeters and x/o's and put the R12 woofers back in their cabs and add new tweeters... and restore the HEDs to normal.
But hopefully the replacement tweeter that's on its way and my original will work for awhile longer. Maybe a good while longer. Said the hopeful optimist.
Thanks again, everyone.You've sent me back into my pile of salvaged bits, which include a pair of dhorms from who knows what system. The first one I opened up has breaks in the wires just next to the terminals. Both of them, so my happy notion of unwinding the voice coil will only work on one of the two breaks. Maybe. Of course the thing that matters is that we stay busy with stuff that interests us right?
OK there's two pairs of these things. At least. Maybe I should just buy new ScanSpeak or something similar. It's just money!
"Honey all those tweeters I've been hoarding are not actually good enough so forget the cruise, we're going to upgrade our audio!"
OK there's two pairs of these things. At least. Maybe I should just buy new ScanSpeak or something similar. It's just money!
"Honey all those tweeters I've been hoarding are not actually good enough so forget the cruise, we're going to upgrade our audio!"
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Hi,
An open tweeter has either fried or has a broken connection wire.
(The connecting wires fail due to long term mechanical fatigue.)
Fried is unfixable.
Broken wire is 50% of the time fairly easy, 50% of the time very tricky,
because for one you can unwind a voice coil turn, the other you can't.
rgds, sreten.
Note that the needle pointing to 0 volts is infinity (open) on the resistance scales,
and 0 on the resistance scales is full scale needle deflection. 0 on voltage is set
mechanically by a screw on the meter. To set 0 on resistance you short the
leads together and adjust the inevitable thumbwheel for that purpose.
An open tweeter has either fried or has a broken connection wire.
(The connecting wires fail due to long term mechanical fatigue.)
Fried is unfixable.
Broken wire is 50% of the time fairly easy, 50% of the time very tricky,
because for one you can unwind a voice coil turn, the other you can't.
rgds, sreten.
An externally hosted image should be here but it was not working when we last tested it.
Note that the needle pointing to 0 volts is infinity (open) on the resistance scales,
and 0 on the resistance scales is full scale needle deflection. 0 on voltage is set
mechanically by a screw on the meter. To set 0 on resistance you short the
leads together and adjust the inevitable thumbwheel for that purpose.
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