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Cerwin Vega Model 26 Woofer Issue

^^ I was hoping someone smarter than me could explain what that spider is actually doing to the performance.

Interesting info about those woofers cimchazz1. Some manufacturers made 4 and 8 ohm versions of the same speaker but they label them clearly as either a 4 ohm or 8 ohm on the rear panel.

Impedance of the driver does affect the crossover behavior since load impedance is part of the equation in addition to capacitance and inductance in the crossover (IOW a crossover/speaker combo is an LCR circuit). If a 4 ohm woofer is dropped into a speaker with a crossover designed for 8 ohms, the crossover frequency of woofer to mid will change by a factor of two! So, while CV may have made two different versions, they should not (if they were smart) have just used 4 and 8 ohm woofers interchangeably w/o changing the crossover. Which they may have done, I have no idea. And really the other driver(s) should be changed as well to match, although some speakers have different impedance drivers and work fine.

[Edit: Crossposted with Skywatcher. I tend to agree it's marketing/labeling rather than that there were two versions.]
 
Did CV use different coils in their Model 26? I noticed there's 2 diffrent versions of the crossover back plate. What do you measure at your terminals?
 
cimchazz1 said:
Thanks, there was a lot wrong with it. I watched him cut it apart. He told me the coil was only about 1/8" into the magnet . I could tell the speaker didn't float right. What a nightmare. Any idea why the 8ohm Heppner was an alternate speaker in these cabs, or are those supposed to be 4 ohm also? I went with 8 so it would match the working one, didn't want to pay to rebuild both to match and then not like them.
Click to expand...

I suppose during the height of production, CV had to outsource an "acceptable" driver to meet the demands of production. Though the one specifically designed for the 26 was the best one suited for the job. It never "hurts" electrically to go to 8 ohm voice coils.It will reduce the current draw on the output transistors of the amp, with the trade-off being you need to notch up the volume knob a bit to get the same decibel levels. One caveat is the mid and tweeter as they will still "sound off" and seem brighter, if not harsh at the higher volume needed to drive the woofer. A fix could be to add a resistor to the tweeter (and maybe mid) to tone it down some. An L-Pad will do the job in most cases, but even then some additional resistance may be needed. Possibly going from an 8 ohm L-Pad to a 16 ohm L-pad to end up where you want to be.
 
cimchazz1 said:
Thanks, there was a lot wrong with it. I watched him cut it apart. He told me the coil was only about 1/8" into the magnet . I could tell the speaker didn't float right. What a nightmare. Any idea why the 8ohm Heppner was an alternate speaker in these cabs, or are those supposed to be 4 ohm also? I went with 8 so it would match the working one, didn't want to pay to rebuild both to match and then not like them.
Click to expand...

I rarely ever "cut apart" a woofer, unless it is completely toasted, or is being completely rebuilt where only the frame is needed. I've even just changed out a spider alone and reassembled the speaker. I have a CV 121-4 (non-L) here I need to do that very thing with. The spider has a "kink" in 2 of the ribs that cause it to "oil can" and make a popping sound. The surround is new and the cone in excellent shape so there is no reason not to do it. :biggrin:
 
Skywatcher said:
I suppose during the height of production, CV had to outsource an "acceptable" driver to meet the demands of production. Though the one specifically designed for the 26 was the best one suited for the job. It never "hurts" electrically to go to 8 ohm voice coils.It will reduce the current draw on the output transistors of the amp, with the trade-off being you need to notch up the volume knob a bit to get the same decibel levels. One caveat is the mid and tweeter as they will still "sound off" and seem brighter, if not harsh at the higher volume needed to drive the woofer. A fix could be to add a resistor to the tweeter (and maybe mid) to tone it down some. An L-Pad will do the job in most cases, but even then some additional resistance may be needed. Possibly going from an 8 ohm L-Pad to a 16 ohm L-pad to end up where you want to be.
Click to expand...
Well, with the Heppners, I can't get that nice balanced "creamy" sound, and the tweeters are harsh when I turn up the volume, and I can never seem to get the bass just right, it's either too boomy or not present enough, frustrating always playing with the knobs trying to get the right sound. I had quit using this system for about 20 years and just put it back in service recently and can't get it to sound right., so I thought I'd start trying to figure out why.
 
cimchazz1 said:
Did CV use different coils in their Model 26? I noticed there's 2 diffrent versions of the crossover back plate. What do you measure at your terminals?
Click to expand...

The 2 different back plates could be either a difference in the crossovers themselves, one for 8 ohm, one for 4 ohm, or it may even just be "cosmetic", or something with "supply and demand" :dunno: It's hard to tell without looking closely to see if the crossovers are different in any way. If they are, then I would guess that would be the reason. I'll see if I have a model 26 to measure at the terminals. But I do have other CV speakers to see what they are.
 
Skywatcher said:
I rarely ever "cut apart" a woofer, unless it is completely toasted, or is being completely rebuilt where only the frame is needed. I've even just changed out a spider alone and reassembled the speaker. I have a CV 121-4 (non-L) here I need to do that very thing with. The spider has a "kink" in 2 of the ribs that cause it to "oil can" and make a popping sound. The surround is new and the cone in excellent shape so there is no reason not to do it. :biggrin:
Click to expand...
I was surprised too. I thought he would pull out a heat gun and melt all the glue, but the foam was cracking (38 yrs old) and the coil was rubbing. Turns out a wind was sticking out/ had come loose from the former. Maybe could have re-used the cone, but the feeling was that it was all incorrect, and maybe the parts were for a 121 (the cone number was CV). It turned out to have a 4 layer coil. He reordered all the correct parts for that Heppner just so we knew what was in it. Now it may not match the other one, but if I think it sounds good enough to spend the money to make the other one match, I'll do it. .
 
toxcrusadr said:
Oh for Pete's sake! :rolleyes:

What a score.
Click to expand...
Well, it was 10 years ago, the guy said he just got it back from the Mac clinic and had it all checked out and bought a whole new system while he was there, so he didn't need this one.. Wish I remembered his address, I would watch for his next garage sale!!
 
cimchazz1 said:
Thanks for aaaaaaallllllllll the help!!! You have definitely opened my eyes!!:music:
Click to expand...

Some people who do "speaker repair" don't pay any mind to the sonics and they will "re-cone" using whatever "fits". Many of those "recone kits" you see say, they will "fit" physically dimension-wise. And that they do. But they use a "one fits all" approach just to sell them. I try to research and find the proper materials, thickness of paper (if it is paper), pressed or non-pressed paper, weight, style, etc. People like "us" actually listen to the music, where others just "make noise" and pay no attention to "how" the music actually sounds. Though there are some shops that do indeed pay attention to detail, there are many others in the "mainstream" that just throw them together and send them back calling them "fixed". I don't trust anybody with my speakers. That's why I do them myself. :beerchug:
 
So now i have a L121-4 speaker that I thought would be the correct speaker for my CV model 26, and it is about1/4" diameter too large to fit the recessed opening to frontload it. That confirms that this cab had the Heppners from the factory (i guess). My Heppner is at the rebuilder and I heard it wont be ready for another month now.
Guess I will look for another set that's 3-way with good reviews for under 400 bucks. I've got a short list, based on reviews I've read here, that includes Klipsch KG4, CV UT12R, CV 29P?, CV 311P, CV D5, JBL4412A, JBL100, Pioneer HPM100?? Maybe even CV 211R, that would be an improvement over my CV model 26 I would guess. Maybe there's others I havent heard about yet?
My room is 28'L x 19'W with wood flooring and an 8' high ceiling.for 1st 14' and 20' ceiling for last 14'. Speakers are in bookshelf holes 32"L x 18H" x 17" Deep, 6' off the floor, so that probably limits me to 12" woofers. Alternate between Mcintosh MA5100 and Pioneer 1010, might be looking into bigger Mcintosh amp soon. Obviously not super expensive "audiophile" stuff, but the best I could get for the money I had in 1977 :)
 
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There's a pair of VS-120s for sale in Livonia on CL and a set of LS-12s in Warren on FB.
 
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