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It finally stopped raining here in Tampa long enough for me to get these older Cerwin Vega V 36D PA Speakers home.
They have some surprises, and disappointments. First of all, for an 18 inch woofer, even with 10 db of boost at 63 hz, they have little bass. Yet, they are anything but bright. The 18 inch driver in these operates up to 1000 hz, and the entire speaker displays what I call a Walter Cronkite coloration, on some male voices. This added warmth quickly becomes objectional, watching Movies or TV News. These speakers have a 2 position toggle switch in the back, one position for Playback, and one for plugging a guitar or keyboards into. The speaker seems to be too subdued in the playback position, and much too bright and forward, in the other position.
The horn midrange is smooth as butter, and the tweeter horn sounds ok.
Believe it or not, these things actually Image.
I have to wonder IF these things might need new capacitors ? I have no idea how old these speakers are, anyone know ?
On Music, especially some old rock, they can sound spectacular at times.
LOL, even a broken clock, is correct twice a day.
Back to that toggle switch, anyone know WHAT it is doing ? Does it simply insert a resistor to the horns, or does it tailor the crossover in some other way ?
Follow Ups:
If you plan to use these for home audio, it MIGHT be possible ( you need to check with someone who really knows about horns) to lower the xover between woofer and midrange to 800Hz or maybe 600Hz wich would probably help clarity of voices and midrange in general.
You may even be able to find someone able to redesign new crossovers more oriented for hi-fi use (Al Klappenberger comes to mind but there are many).
Keep in mind a PA speaker has a crossover optimized for maximum power handling and maximum output. You might be able to use a different crossover if 127dB is not your ultimate goal.
That may be a great idea!
Yes, these will never see professional use, only my listening/family room.
I was told you have to be careful crossing to a horn mid range too low, because it can cause Squak ?
Besides power handling issues.
That's where my knowledge stops. Wether it will or will not be doable depends on the compression driver and horn used. More specialized people may help you :)
My horn sound great with a 400Hz crossover. ;) but the midrange horn has a low enough cutoff, and the midrange driver is able to be crossed that low without damage, wich is probably not the case with yours.
Edits: 08/21/17
Then, I need a Cerwin Vega V 36D crossover schematic.
There is a guy up at Madisound who is a Ham Radio Operator like me, who is into Horns, big time!
I bet he would help me
It shows all the drivers, etc, etc.
How often do you replace the midrange and tweeter domes ?
I know the midrange dome is made of aluminum, and aluminum is said to fatigue.
How long do domes last, and how do you know if they are going bad or not ?
The lack of bass is to be expected. They were made to operate above 80Hz, gaining sensitivity by sacrificing low frequency extension. With adequate EQ, as in no less than 1/3 octave resolution, they can be made to sound OK, but they'll never go really low.
I'd assume the playback position is for recorded sources, and that the guitar/key position bypasses the tweeter, which would get blown in short order by a heavily distorted guitar or synth.
LOL, at me! I thought I ordered 5% 3.9 mfd 250 volt Mylar caps to replace the 4 mfd 100 volt aluminum electrolytic caps, but here is what I ordered
Bennic XPP 3.9 mfd Non-Polar Metalized Polypropylene Film Capacitor 250V
Thanks Bill!
The box is tuned to 45 hz, according to the CV poop sheet
I will listen to see if the tweeter is being switched out of circuit with the switch, but they are very noticeably brighter, with the switch in the guitar.keyboard position.
I pulled one crossover, and all caps except one is Mylar. There is a 4 mfd 100 volt non polar electrolytic in there. I just ordered a couple 5% 3.9 mfd 200 volt Mylar caps from Madisound to replace the only electrolytic in the crossover.
45Hz tuning doesn't equate to 45Hz response, especially with a very low Qes woofer, which it probably has. Low Qes is what gives a woofer high sensitivity and extended high frequency range, but it also limits the low frequency extension.
Most woofers, when you give them a light push in the center of the cone, will move quite a ways.
These barely move. Is that normal for this type of woofer/surround ?
Assuming it's a cloth surround, typical with pro-sound drivers, it will be much stiffer than the foam or rubber surrounds used in most consumer sound drivers.
Yes, it appears to be cloth, like an accordian.
When I flipped the speakers on their face to pull a crossover, I noticed the toggle switch in the back has 2 positions Vocal and Playback, not what I originally said.
I had them in Playback, so I switched into Vocals.
MUCH better!
Now, all that woofy muffled sound is gone on TV and Movies.
I just watched War Games, and it sounded great.
I have them almost in the corners, 2 or 3 feet out, and firing right at me, across the room.
My room is approx 20 by 24, and they illuminate it very well.
I traded a guy a real nice receiver for a Legacy Dual Impact Subwoofer some time ago. So, just for shits and giggles, I engaged the subwoofer, thinking it could not keep up with these speakers. Guess what, it keeps up pretty darn good.
I am running them flat, and letting the subwoofer pick up the bottom.
Ok, I layed one speaker down, and pulled the crossover. All Caps are Mylar, except one 4 mfd 100 volt Aluminum Electrolytic.
The woofer to midrange horn crossover is at 1000 hz
If this old aluminum electrolytic cap is part of the high pass of the woofer, and it has lost capacitance over the years, wouldn't that make the woofer play higher in frequency ?
Mylar Capacitors are said to outlive you, but that Bob Crites guy says they can get high ESR over the years, and should be replaced. Of course, he sells capacitors.
Any comments or suggestions ?
4 uf is way to small for the woofer cap., more likely the
tweeter. It's probably still good, but might as well order
a Dayton PP cap while you're at it.
It is the ONLY Electrolytic Cap in there, all the rest are Mylar.
This Cap is about 2.5 inches long. I could not find a physically close in size 4 mfd 100 volt Electrolytic Cap. Today's Non Polar Electrolytic Caps are physically tiny, so I ordered a Bennic Metallized Polyproplyne Cap. The circuit calls for a 10% 4 mfd 100 volt, so I ordered 5% 3.9 mfd 250 volt cap.
I wish I had a crossover schematic, so I can understand WHY all the caps are Mylar, except the one Electrolytic ?
These Cerwin Vega V 36D speakers are from the early 90's I think, so that would make them 27 years old, kind of a long time, for an Aluminum Electrolytic.
I figure the Mylar Caps, are still good.
What about the speaker diaphragms, how long do they usually last, and how do you tell when they are going bad ?
VERY STRANGE that the cap is that long, being electrolytic.
Even a 40uf in only 1.25" or so., Maybe a 400 uf?.
That horn won't load the driver well below 500 Hz, so you're
kind of stuck with the orig. x-over points. Minimum I'd say
around 800 Hz.
I tried to take a picture of it, but my family room is pretty dark, and even though the cell phone camera flashed, it didn't come out very good.
I freaked too, at the size of that cap, but remember, these bastards are 27 years old.
LOL, I am really jury rigged right now, running 25 feet of 24 gage twisted alarm wire to them. Hey, it is copper at least. My 12 gage wire will be here this week.
I am also just powering them with an Onkyo receiver the NR 809, because it has Audyssey and a 1/2 ass equalizer built in.
However, I have a QSC PLS series amp, as well as a 60 lb Apogee Amp, that is a beast.
I would expect the electrolytic to be a shunt to ground on the low pass section of the midrange filter, as the higher ESR wouldn't be a problem there. But it's still odd, since 4uF mylars and polys aren't at all expensive.
I know, but whatever it is, it is getting replaced.
I always thought that Mylar Caps can outlive people, but some say they get high ESR, after 20 + years ?
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