Cerwin Vega Frankenstein Project

[johnrotten 1,092]

The CV2000-15 that I did work on had a separate enclosure built in. I think it was rather flimsy and I used silicone caulking to help seal it better.

[Carverpro 672]

Ok I fixed the problem.  I wrapped some clothes dryer hose aluminum tape around the basket holes sealing them up. I then made a little wall strip (lip )out of cardboard to seal up the gap around the positive and negative wire terminals...just like the at15's mids.

...I then pumped about 500 watts through the speakers. No midrange cone movement.  My god these things are intense. I put on some rap/dance to check for any rattles from the new faceplate I fabricated...nothing. vocals are loud and deep bass response. Feels like I have a huge sub in the room. Very beefy looking. Have to wait till Monday to post a few pics.

--------- I need to talk to someone about impedance. I have never seen the following...each speaker has two 8 ohm mids wired in parallel for 4 ohms. When I went to connect the speaker wires to the mids ...on the - and + terminal...they have a big black dot " over " the positive terminal!?? Is this a screw up from cerwin vega during assembly? All 4 mids are done like this.

...I followed the same set up as on the at 15 mids.  I went by the actual - and + terminal markings ignoring the black dot over the positive terminal. So right now I am either running 4 or 16 ohms for the mids. How can I tell which way is correct?? The tweeter is 4 ohms...as is the woofer. If the mids are at 16 ohms...what's the overall impedance?

Thanks....

 

 

 

[Brian_at_HHH 2,691]

Way to go @Carverpro !   Sounds like you've created some incredible "monsters," Dr. F.

 

Wish I could offer info on your impedance query, but I am curious what the answer is. 

[Bobby1970 1,451]

...have you tried the DMM leads to the speaker terminals?☺️

[Carverpro 672]

Ok..I went on the cerwin vega forum and apparently this is normal with a lot of vega models for phasing to get the best possible sound.  Reversed polarity. This is done on the mids and tweeters. The wiring is reversed.

...when I cracked open my at15's a long time ago this was not the case...  positive wire to positive terminal....negative wire to negative terminal on both mids and tweets.

...so the way its wired now..should be the same way I had my at15' mids wired.

[Carverpro 672]

1 hour ago, Brian_at_HHH said:

Way to go @Carverpro !   Sounds like you've created some incredible "monsters," Dr. F.

 

Wish I could offer info on your impedance query, but I am curious what the answer is. 

They look pretty mean. My uploading sucks here at my place. Have to wait till Monday to use the wifi at work. This " hybred" is like having a blend of home/pa speakers. Loud and deep.

[Turbo 1,403]

1 hour ago, Carverpro said:

--------- I need to talk to someone about impedance. I have never seen the following...each speaker has two 8 ohm mids wired in parallel for 4 ohms.

 

 

 

I would simply measure each individual mid driver on my trusty Fluke 187 DVM.  This will reveal the characteristic DC resistance of each driver.  If it reads near 8 ohms then you know the DC resistance of each driver.  Then you could wire them together in parallel and you should see roughly half as much DC resistance through them for about 4 ohms.  Impedance is a dynamic AC swept measurement across a frequency range usually from 20Hz-20kHz.  The characteristic impedance will vary quite a bit over this frequency range for drivers.  But it doesn't matter here if you only want to know the DC resistance for your Mid drivers when wired in parallel.

 

Them my cents,

 

Turbo

[Carverpro 672]

Only thing left to do now is hunt down some crushed black velvet for the front baffle that I built for the mids and tweets...and this project will be  complete.?

[Carverpro 672]

Tracked down some crushed velvet. I can get black or red. Hmmmmmm...black bottom where the woofer goes and for the new faceplate I made....perhaps red with the black mids and tweet might look killer. Make these Cerwin Vega monsters look really unique and stand out...what do you think? Or just keep it traditional black?

[Brian_at_HHH 2,691]

2 hours ago, Carverpro said:

I can get black or red.

 

Ouch, that's a tough choice, given the speakers.  I can easily see great reasons to go either way.

[Zoom 373]

17 hours ago, Turbo said:

I would simply measure each individual mid driver on my trusty Fluke 187 DVM.  This will reveal the characteristic DC resistance of each driver.  If it reads near 8 ohms then you know the DC resistance of each driver.  Then you could wire them together in parallel and you should see roughly half as much DC resistance through them for about 4 ohms.  Impedance is a dynamic AC swept measurement across a frequency range usually from 20Hz-20kHz.  The characteristic impedance will vary quite a bit over this frequency range for drivers.  But it doesn't matter here if you only want to know the DC resistance for your Mid drivers when wired in parallel.

 

Them my cents,

 

Turbo

 

Turbo has it here. 

Just a little clarification maybe from my days wiring ‘seperates’ in car audio. 

‘Overall impedance’ matters little in relation  to impedance at any given frequency. 

Ie if your bass drivers are ‘listed’ at 4 ohms resistance, the frequency sent there from your crossover will load your amp at that frequency at 4ohms.

The same for your mid frequencies, and high etc.  

That’s  why some speakers are said to be ‘amp hungry’. Like our Vegas. They load amps at half the resistance so twice the load.  Weak amps get hot and ornery when presented with that load for extended periods.  Some reference series Infinities load certain frequencies at an ohm or under. (The Kappas, especially the Kappa 9)

You start running into problems when you start overlapping frequencies with incorrect or incompatible crossovers (like we used to with multiple separates in cars) 

overlapping frequencies will further load that freq range with the resistance of the corresponding driver. 

You wont have that problem since you are still using the crossovers that were engineered to slope the crossover cutoff properly and not overlap frequencies.  

Using those cv crossovers, the only way you can change the load (you are correct here for sure) is changing from series to parallel with the drivers.  

 

A couple more cents for what they’re worth. 

 

Edited April 7, 2019 by Zoom

[Carverpro 672]

[Daddyjt 9,617]

They look eerily familiar, lol. 

 

How do they sound?

 

[Carverpro 672]

57 minutes ago, Daddyjt said:

They look eerily familiar, lol. 

 

How do they sound?

 

They sound awesome.  The bigger mids definately strengthens the vocals. Surprisingly the image has improved.  The sound is more centralized. Last night was the first time I had a chance to beat on them for about 5 hrs. On hour 3 of listening to deadmause at 400+ watts...I heard a rattling coming from the right speaker.. sounded like a voice coil failing. Fortunately,  it was the cabinet itself. I pushed in on the back panel and the rattling went away. Guess I have to beef up the bracing. Listening to Neil young was insane!

Edited April 8, 2019 by Carverpro

[Carverpro 672]

This is the extremes I had to go to for the mids. Had to totally seal up the holes in the basket and the gap behind the wire terminal leading into the spider and such. Very crude looking but very Effective. I can not imagine this hurting the sound quality...but i could be wrong?

[Brian_at_HHH 2,691]

All I can say is WOW - beautiful work!  And I'm really glad to hear how fantastic they sound. 

 

All in all an amazing project - thanks for letting us follow along.

[Daddyjt 9,617]

4 hours ago, Carverpro said:

This is the extremes I had to go to for the mids. Had to totally seal up the holes in the basket and the gap behind the wire terminal leading into the spider and such. Very crude looking but very Effective. I can not imagine this hurting the sound quality...but i could be wrong?

 

Do the mids not have their own sealed chamber?

[Brian_at_HHH 2,691]

@Daddyjt if you go WAY back in this, you'll see that there wasn't a separate chamber for the mids, and that Carverpro was worried about changing the acoustic effect if he created one.  He found that without something to baffle the back of the mids the woofer was pushing them, as you might expect with something that big, and the air it moves.

[Daddyjt 9,617]

58 minutes ago, Brian_at_HHH said:

@Daddyjt if you go WAY back in this, you'll see that there wasn't a separate chamber for the mids, and that Carverpro was worried about changing the acoustic effect if he created one.  He found that without something to baffle the back of the mids the woofer was pushing them, as you might expect with something that big, and the air it moves.

 

Ok, that makes sense - sorry for the oversight. 

 

In that case, maybe something like this might be a better permanent  solution...

 

https://www.ebay.com/itm/NEW-SPEAKER-BAFFLES-PROTECTORS-UNIVERSAL-6-5-OR-5-25-PAIR-CAR-SPEAKERS/272892716727?hash=item3f89ac66b7:g:vagAAMXQMXRQ9HPN

 

 

[Carverpro 672]

8 minutes ago, Daddyjt said:

 

Ok, that makes sense - sorry for the oversight. 

 

In that case, maybe something like this might be a better permanent  solution...

 

https://www.ebay.com/itm/NEW-SPEAKER-BAFFLES-PROTECTORS-UNIVERSAL-6-5-OR-5-25-PAIR-CAR-SPEAKERS/272892716727?hash=item3f89ac66b7:g:vagAAMXQMXRQ9HPN

 

 

Yes...I was considering this option. Still may do it. I'm just glad I didnt have to rip that face plate off and build a sealed enclosure for the mids...and to be perfectly honest with you the mids in the at-15's had no sealed chamber behind them. The se380's " did " have small pods  behind the mids packed hard with pink fiberglass insulation. I actually thought this was done for sound quality and not to keep the waves from the bass from interfering with mids performance. A critical error on my part. Luckily it got resolved.?

[Carverpro 672]

Eminence makes some awesome sounding drivers that have a high sensitivity rating. They actually sell a nice 6.5 inch " sealed "driver that is 8 ohms and has a 97 db 1w1m rating. The 6.5 inch cerwin Vegas I'm using are 8 ohms with probably a rating of about 91. Swapping out the mids would boost the vocals once again. Just trying to constantly improve. Though I'm impressed with the current set up. Last night it felt like my ribs were vibrating. Could have also been what I was smoking...lol

[Carverpro 672]

I guess 400+ watts from this Carver amp going into the cabinets for 5 hours at a time is proving to be too much. The speakers are starting to protest. Blew the upper right corner seam apart.

[Brian_at_HHH 2,691]

2 hours ago, Carverpro said:

I guess 400+ watts from this Carver amp going into the cabinets for 5 hours at a time is proving to be too much. The speakers are starting to protest. Blew the upper right corner seam apart.

 

OOPS!  I guess we now know which seams you didn't reglue ... yet.

[Carverpro 672]

I never touched that part of the cabinet whe modifying. Trying to fix with glue, silicone and screws. 

[Carverpro 672]

I spent all week fixing the upper split in the corner and doubling up on the bracing inside. Glued, screwed and siliconed. Made no difference whatsoever.  When cranked the rear wall of the enclosure is rattling( slapping). And once again if I push in on the back hard the vibration disappears. I have no idea how to fix this? ...aside from sticking a 2×4 under the bottom woofer on the floor to prevent the speaker from moving ahead while I wedge a 2×4 in between the back of the enclosure and the actual wall(drywall)...lol. I guess modifying the At15 enclosures weakened the internal  structural integrity.  Time to built a set of enclosures from scratch.

Edited April 13, 2019 by Carverpro