desertrat748
Super Member
I’m sure the 12 “ are all the same spacing. I don’t think CV would make separate jigs for various cabinets. All the CV ones that I have swapped out were the same.
Cerwin Vega speaker help needed
- Thread starter gagecalman
- Start date
All the cast aluminum frame woofers are the same mounting in their respective sizes. All 12" are the same, all 15" are the same, as are the 8", and 10". The steel ones are also the same in their respective sizes. But the 12" steel vs aluminum are different as you already know.
So any CV aluminum woofer will "fit" physically. Whether it sounds right for the cabinet is another story. The voice coil size doesn't matter near as much as the type, weight, and style of cone used. If someone has a known original woofer in their 123, or 1230, there is a number on the backside of the cone. A photo would help of both the backside of the cone, and the front side to help determine which cone it is.
desertrat748
Super Member
All the cast aluminum frame woofers are the same mounting in their respective sizes. All 12" are the same, all 15" are the same, as are the 8", and 10". The steel ones are also the same in their respective sizes. But the 12" steel vs aluminum are different as you already know.
I ll disassemble my cabinet with the original 1980 U123 drivers.
Give me a few minutes and I hope that I don’t strip out the screws like the last one.
Yeah those plastic inserts can be a real pain. They push back through so easily, and then "spin" as you try to tighten the screw. I had to glue them back in, wait overnight, then apply some hot glue over them on the inside to keep them in. The aging particle board doesn't help any.
desertrat748
Super Member
That is so true. I’m living out in the desert and that particular board is dried out and crumbled when I touched it. Two of the plastic inserts popped of on the other cabinet. !! Dang it!
On my one 29P, I had to spin the woofer a little and carefully drill 4 new holes the right size for the inserts to fit snugly. They were tight enough in the holes I couldn't push them in very far and used the screws to draw them in. Use a screwdriver that fits the screws properly so you don't need to push on them. I much prefer hex head screws over Phillips (or JIS cross for metric).
desertrat748
Super Member
Okay, are you guys ready for this? Cim, you’re going to be very pleased and your worries laid to rest.
The cabinet is marked as 1230 inside. Both are marked that way. So they are being called model 1230 from certain Vega when they make the cabinets. On the back of mine they are marked model U123. So it appears that U123 are 1230 s.
The woofers are indeed the L121-4 models. I’m still trying to unpack everything I have in storage to find my original L121-4 as now I have discovered that my other one is that 2inch VC LSW. I’m thinking maybe I should get another LSW? To match them?
I don’t notice anything different about the two. Both sound excellent and maybe the only thing I noticed is that the one can handle a little bit more power before it breaks up.
Send me a private message (conversation) if you have one laying around.
Here’s the pics. Does anyone know what the capacitor is on there marked 1.5? 1.5 uF? Doesn’t say.
NAD80
Super Member
Have used this as a reference for Part #. http://www.oaktreevintage.com/Cerwin_Vega_Speaker_Parts.htm Had a pair of R-10's. Changed the breaker out for a fuse of the same value. Was giving me intermittent operation.
desertrat748
Super Member
Yes I looked there. Didn’t have anything listed for what I needed.
desertrat748
Super Member
Now who’s going to come over and help me get this buttoned up w/o damaging the screw backs?
Yes, it's a 1.5uf/200v film capacitor.
Is the cone on the woofer smooth on the front face? Or is it a ribbed cone?
Hey DR, just got to reading all these. Thanks for the updates, interesting!! Sorry to hear about the problems you are having with your wood.
Stripped I have fixes for, crumbling I don't. Skywatcher has much more experiencing with repairing speakers than I do. I would probably try to JB Weld some nuts with integral washer to the backs of the holes and use machine screws, or do something else goofy like that. I like to use JB weld for everything. It would a, but it is black and shows. There are other clear epoxies that repair wood, too. They must have been kinda loose to begin with maybe, wonder why the vibration wouldn't destroy the wood?
Are those date codes of '79 58 and 38 on your pots? Hard to see in pic.
Very interesting you found the 1230. I posted pics of my X-over showing cap values a few postings back.
As far as I can tell, the W121-4 is the (maybe) 6 ohm version of the L121-4 ??? But I can easily rebuild them to L121-4. Same 1.5VC, basket probably. But the magnet "bump out" on the W doesnt have the center post showing out the back, not sure what that means???
I WOULD come and help if I were closer!!
Just want to add that after you posted this, it "dawned" on me that I had a loose screw too (in more ways than one), so I went back and looked and sure enough, the same problem. The insert was loose in the bottom of the box and the wood was messed up. I had originally just figured the threads stripped out of the wood and put the grille back on.
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NAD, thanks for the chart. So I see why the 6" HED mids I see on "the Bay" wont fit my cabs, I'm supposed to have FM6 5.5". My screw holes are about 4 5/8" apart across the speaker. And I see the L121-4. Well, I have 1, not I need another rib cone L121-4 to match. Those 121 were used in many cabs.
As far as I know, there were never any 6 ohm woofers back in the vintage years. Most woofers were 4 ohms (nominal). Very few were 8 ohms. But with the combination of the drivers, inductors, resistors, and capacitors you may end up with an "average" equivalent of near 8 ohms impedance. But I have rebuilt some specifically with 8 ohm voice coils for specific reasons and/or certain amplifiers. Measuring a voice coil with an ohm meter only gives you an "idea" what the impedance is. Say you measure a coil to be 5.1 ohms, then "zero" out the leads of the meter and see what it reads then to account for the resistance in the leads. Then, let's say you have 0.4 ohms in the leads. Deduct that from the 5.1 ohm reading and you end up with 4.7 ohms. That puts the voice coil in the 4 ohm "class". A voice coil is an inductor in a magnetic field, not a "resistor" per se" The impedance (load) varies with frequency. Chances are the W121-4 just has a different cone, and possibly a different strength magnet. But I do not know the specifics.
Thanks Sky, I'm gonna put 'em in after the surrounds/cones/coils are repaired and give 'em a try.
From what I can "see", the dust covers are 1" dia larger (cuts the higher frequency) and the coils show 5.1 on the ohm meter (probably 4 ohm). So they should "drive" easier?
I'm not sure what the smooth magnet bump-out indicates about magnet size, never opened one up.
What would the possible change be if 8 ohm L121-4 with a 2.75 dia dust cap was original? Less woofer mids and more power to woofer than mid and tweeter, so woofer is a little over powering? Could I add a 3 ohm resistor somewhere to get it back toward 8 ohms?
From what I can "see", the dust covers are 1" dia larger (cuts the higher frequency) and the coils show 5.1 on the ohm meter (probably 4 ohm). So they should "drive" easier?
I'm not sure what the smooth magnet bump-out indicates about magnet size, never opened one up.
What would the possible change be if 8 ohm L121-4 with a 2.75 dia dust cap was original? Less woofer mids and more power to woofer than mid and tweeter, so woofer is a little over powering? Could I add a 3 ohm resistor somewhere to get it back toward 8 ohms?
Ok, got the mids !
DR, here's some other ideas for wood repair. Rotating the speaker is good, but it turns the dustcap logo sideways, probably not something you want?
https://www.thegearpage.net/board/i...ing-old-fender-particle-board-baffles.937639/
I have been reading all the different fixes, sounds like a common issue. Especially if someone has glued a screw in sometime in the past and tried to remove it later.
DR, here's some other ideas for wood repair. Rotating the speaker is good, but it turns the dustcap logo sideways, probably not something you want?
https://www.thegearpage.net/board/i...ing-old-fender-particle-board-baffles.937639/
I have been reading all the different fixes, sounds like a common issue. Especially if someone has glued a screw in sometime in the past and tried to remove it later.
2.75" is the right dust cap for the 1.5" voice coil.
No, you cannot add a resistor to a woofer and magically make it 8 Ohm.
The "smooth" hump in the magnet probably doesn't mean anything more than a different way the pole piece was attached to the plate.
8 Ohms vs 4 Ohms.. Well it won't change the sound. However a 4 Ohm driver will put a higher load on the amplifier and heat it up more. There is less "resistance" so it draws more current out of the amplifier, which in turn heats up the output transistors. When you see the "watts" of a speaker, or output transistor, it means "heat". How many "watts" (heat) can the device dissipate before burning up. Look at the speaker terminals on the back of your amp. Most amps will tell you what impedance they are designed for. Some will "handle" 4 ohms, BUT on ONE set of speaker terminals only. If the amp says "A+B must be 8 Ohms or higher", then using both A+B with 4 ohm speakers will exceed the design specs. However you can get away with it as long as you don't crank it up too high. Just be mindful of how hot the amplifier is getting. The same for speaker voice coils. If it is rated for 100 watts RMS, or "continuous", then that's the amount of constant heat it is able to dissipate before burning up. The "peak" rating is just that, an occasional peak beyond the RMS rating where the voice coil can cool back down before another peak comes along. Air flowing over the heatsink in an amp is what cools it. That's why you never restrict the air flow. In a speaker, the air being "forced" past the voice coil is what cools it. As the cone moves in and out, so does air. The spider is an open weave so air passes through it. The felt dust cap on a CV speaker is a bit of a compromise where it's not "sealed", but it is choked off enough to force air past the voice coil. That's (mainly) why the proper size CV felt dust cap is essential. The felt cap also dampens some of the "noise" coming from the voice coil itself.