Cerwin Vega cabinets

[Leppy]

Hi all, just done my intro's.A few weeks ago I picked up for a song a pair of Cerwin Vega vs120 cabinets in as new condition. They're fitted with a mckenzie 12" full range speaker which I can't find any info or images of on the net, but a mid range and tweeter have never been fitted. I need a 4" mid range and 1" tweeter, holes are 4" and 2". Found an audax 4" midrange on fleabay yesterday for a tenner so bought it hoping to find another later. Then later saw some Mordaunt Short speakers with no info for £10. Told they were ms10's and I have a pair so checked and they're fitted with audax 4" and 1" tweeters and crossover. Got them for £16 so my intention is to fit the MS speakers into the mid range and tweeter holes and bi-amp them from a denon avr 2307 (which I've already done with a pair of Lynn helix), so one set of leads going to the McKenzies (12 ohm) and the other leads going to the mid and tweeters (8ohm). I can't see why this isn't feasible but would be grateful for comments. The McKenzies at the moment in the Vegas are bassy but very warm and light on the highs.

[walpurgis]

Frank, if you're having fun, that's the main thing, but I think you may find a mix of unmatched drivers of varying impedances and sensitivities a little problematic.

Your best bet may be to use the McKenzie drivers as near full range and just reinforce the top end with a tweeter on a simple capacitor filter.

[Filterlab]

Your best bet may be to use the McKenzie drivers as near full range and just reinforce the top end with a tweeter on a simple capacitor filter.

Or even better, some originals...

https://www.ebay.co.uk/itm/392866638861

https://www.ebay.co.uk/itm/193597518439

Assuming the McKenzie drivers are a close match to the original specs, it’ll give you correct impedance and roll off matching throughout the register. Are the original crossovers are present?

https://www.ebay.co.uk/itm/114324288078

[Leppy]

The crossovers aren't there because the cabinets have never been fitted with mid range or tweeters. There has only ever been the mckenzies fitted.The cabinets are as new, which is why I want to play with them. The midranges you linked are perfect, same imp as the Macs but the tweeter look like 4 ohm. Is that usual. The fact that I'm going to bi-amp, one to the mac 12 ohm and one to the mid and tweeter with a crossover 8 ohm would that matter with the difference in imp. Also with the macs being full range what effect will having mids and tweeters have or is it just a case of fit em and see.
I watched the video on setting up and the positioning from rear and side walls ideally being the same. My Lynn Helix state they're designed to be close to the rear wall and about a mtr from the side walls and they certainly sound so much better being bi-amped and in this setup.

[Macca]

You're still going to need some kind of active or passive crossover though.

[Filterlab]

It's not necessary for all the drive units to have the same impedance, as two and three way speakers often don't - let's face it, a tweeter will rarely place a greater electrical load on an amplifier than a bass driver.

What is critically important is that the crossovers in the speakers should be exactly right for the drive units. If they're not, then you'll end up with all sorts of mess; missing frequency ranges, strange peaks at certain frequencies, and in the worst case scenario, burned out drive units that have been 'exposed' to frequencies outside of their capability to handle at certain volumes. I’ve seen tweeters physically melted into a lump due to incorrect crossovers.

If the original CV drive units have different impedances then it matters not if the original crossovers are there. Yes, you could use a random pair of crossovers, but see above in that case.

You have three scenarios for the best results...

1. Get the original VS mid and treble drivers, and the crossovers. Try them with the McKenzie drivers. In real life, bass drivers are the hardest to damage and can be exposed to any frequency input - they're designed to take a lot of power and move a lot. They might just sound good.

2. Not nearly as ideal, but find if you can some matching McKenzie mid and treble drivers and some McKenzie crossovers - or crossovers recommended by them. At least you'll have a proper mathematically calculated set of drivers and crossovers. Although they won't be designed for the cabinets, they may sound ok.

3. Find some similar three way speakers with damaged cabinets and transplant the whole caboodle into the CV cabinets. Again, the driver-to-cabinet match may not be ideal, but it should be ok-ish.

Whatever way you go, you'll have a lot of fun doing it! I used to mess around with speakers in this way; it's how I discovered that there's a LOT more to speaker design than popping drivers and crossover in cabinets! :lol:

[Techno Commander]

I would avoid the original CV tweeters. Many years ago as an impressionable youngster, I bought a pair of CV AT100s. To say the treble was "in your face" was an understatement. They were very shrill and harsh, considering that most CVs are designed as "party speakers", there is a certain lack of finesse. I fitted a pair of Morel soft domes which helped immensely.
Also, the cabinets themselves are quite thin and hollow sounding for their size. Some additional bracing wouldnt go amiss.

[Filterlab]

Yes, CV speakers were never what you'd call subtle. I remember What Hi-Fi reviewing a pair and saying "they're great, if you want to hear the canons in Pachelbel's Canon".

:lol:

[Leppy]

Thanks for all the comments. As you,ve probably realised I,m not a purist and my kit is fairly modest. I was originally going to use the 4" driver ,tweeter and crossover from a pair of Mordaunt short MS10 's because they fitted the holes in the Vega cabs to supplement the 12" McKenzies. I found a pair of 7" mid, crossover and tweeter, new but unused dating from '88, 8 ohm, 40w made by Hi.co which I can't find any info on but don't imagine they're anything special from the connections on the speaker terminal.Rather than cut the cabs at this point I made a couple of spacers to bring the mids forward by 50mm so the rear fitted into the 4" tube . I bi-amped them to the denon avr 2307 and I have to admit the difference is astonishing, much better than I expected. The thumping bass is much more subtle now. I think the amp feeding the McKenzies is default at 80 hz but can be altered , haven't tried doing that yet. The amp is on pure direct sound setting. I played a Hifi sound stereo test record (1974) to check the phasing and also the turntable setup, all good. Then used a Tag McLaren test cd with very detailed recordings and again it sounded lovely, so I'm very pleased. I think my Linn Helix speakers have slightly more detail but the vegas have a little more warmth. I,ve seen various comments saying Bi-amping doesn't really make a difference but from my playing around seems to me it does, or maybe it's just placement of the speakers, which I do realise is much more important. It's been fun and stupidly cheap, about £50 in all.

[Filterlab]

Well, for 50 notes it sounds like a lot of fun! Do you have any pictures of your DIYing at all, it sounds very interesting? :)

Great fun messing about with speakers.

[Leppy]

283512835228353

Tried to turn them . I'm going to recut the midrange aperture so it fits properly. The only problem might be the diameter of the tube behind the mid. I can't get into the cabinets so the only access is through the 12" aperture and there's crossbracing between that and the tube so it may be that I'll still have to pack them out. I have the covers so they would hide the packing.

[walpurgis]

You could have some fun with a decent but second hand mic and free audio analysing software off the net.

[Filterlab]

I love them! There’s a good, solid honesty about them. Cracking DIY.

[Leppy]

Managed to properly fit the mid range without the spacers. Incredibly tight as you can see from the pics and I needed to cut the cabs right to the edge of the mid range tubes. Very pleased. 283572835828359

[Filterlab]

Nice. They look original now. Good stuff.