Want to restore a kinda old speaker... (1 Viewer)

[Mark Larson]

I just got an old speaker from a friend of mine, with those adjustments for treble and mid on the speaker itself. I tried it out, and holy of holies, IT WORKS!! It says Acoustic studio monitor on the front, and has a sensitivity of 95 db/Watt.
Now, there are a few problems with that speaker, and i'd appreciate it if you guys could help me out with that...
1. The black finish is scratched on the top, probably from frat parties. Any ideas on what product i can use to clear out the scratches and polish the wood to make it look a bit better?
2. The tweeter doesn't work - it looks like a 3-way, with a small (cone! :frowning tweeter, a mid-range, and a 12" woofer. When i put my ear to the speaker, the sound is only coming out of the mid and the woof. I understand it is really bad to not have any highs, so what do you suggest i should do? The tweeter looks like a 2".
3. The woofer has to go - it is a Cerwin Vega 'Stealth' model, and i want to replace it with something nice ASAP. (A car woofer? )The only problem i foresee is that the driver may not be optimised for the cabinet. However, it already looks like a replacement, and the paper cone is getting tatty - it is grey and looks 'orrible. Should i try painting the current woofer over with something to give me better sound? I seem to remember some website giving advice on painting paper cones with a commonly-available solution to help with rigidity.
Thanks for reading this far!
Any ideas will be welcome!!
Mark

 

[Dave Poehlman]

The woofer has to go...Should i try painting the current woofer over with something to give me better sound?

Give us some more specs on the woofer (size & ohms) and the enclosure (volume, ported, length/diameter of port) and perhaps one of the tech-heads here could find something that'll work. As far as painting it, you could try it.. it wont give you much more as far as rigidity goes, unless you use heavy paint.. and that'll change the parameters of the driver.

 

[Mark Larson]

Ok, what i know is this:
The volume (taking into account 3/4in MDF) is 1.89 cu ft - 53.5 liter.
The impedance is 8 ohms AFAIK. Is it possible for the woofer to have a different impedance from the rest of the speaker? Don't think so, right?
It is supposed to go till 20 hz, however i have no illusions.
I have no idea of the rest of the parameters/measurements of the woofer, sorry.
BTW: Is it possible to use this as a subwoofer by disconnecting the tweet and the mid and using a plate amp to power a Shiva or original SVS driver? *droool*

 

[Dave Poehlman]

Is it possible for the woofer to have a different impedance from the rest of the speaker? Don't think so, right?

Not without re-engineering the crossover. Which brings me to another point.. replacing a driver with a different model may not always yield an improvment in sound. If a crossover is designed for a driver's specific frequency response... changing the driver might actually make things sound worse. However, I would say crossovers of that specialized nature are only found in higher-end systems. So, if these aren't high-end speakers, you will have a better chance finding a driver that will fit since there's probably a "generic" crossover in there (if there is a crossover at all).

What size is the woofer? 8" 10" 12"

 

[Mark Larson]

The speaker is definitely not at all hgh-end. As i mentioned, the driver currently says Cerwin-Vega, so it can't be all that high-end!
The woofer is 12", and yes it is ported, but i'll have to post the dimensions later. It looks like a 3" dia though.
Thanks for the help man!

 

[Dave Poehlman]

Well using Parts Express' "Speaker Selection Wizard", they recommend the Eminence Omega P. However the price tag is $151.68.

BTW: Is it possible to use this as a subwoofer by disconnecting the tweet and the mid and using a plate amp to power a Shiva or original SVS driver?

You could stick a Shiva in there... it will probably sound a little boomy in that small of an enclosure and you would want to put in a wider diameter/longer port.. the Shiva would probably make that 3" port chug like a locomotive.
If it were my project, I would probably just drop a Dayton 12" driver in there ($76.50), change that port to around 13.75 inches in length (tuned to 25Hz), pick up a decent mid and tweeter to fit the same cutouts, slap together a simple crossover (if there is none in there), stick on some nice wood veneer and call it a day.

 

[Mark Larson]

Ok, the port is even smaller than i thought - 2.5" dia, and 4.5" length.

Is there an easy way to replace the ports in these things?

 

[Dave Poehlman]

Im not sure how it's mounted in there.. on my old college speakers (Fisher.. this was before I knew anything about DIY.. or good audio for that matter) the ports were just stuck in the hole.. a little tug and they came right out.

It's probably really thin plastic so your port cutout is probably around 2.5" also. To go with a 3" port made of heavy duty PVC, for example, you would need to widen that hole to 3.5", probably with a jig saw.. or hole saw... you could get away with keeping the port.. it would just be tuned to around 33Hz and you may hear a little boom.. either way, you should get pretty solid response down to 40Hz before it starts rolling off.

Now wait a minute... that enclosure is close to the ideal size for a sealed setup with the same driver... you'd get a flatter response.. but you'd sacrifice bass extension a bit.

 

[Mark Larson]

Can i go sealed and get a more musical sub? Or is it not worth it with that driver? I would like to have a sub that goes lower, but even a sealed setup would be good.
The reason a sub would be better is that i don't have two of those, so i can't even use them as surrounds when i get a 5 ch receiver.
Another thing: i don't have a surround receiver yet, so i have two options:
Use a sub cable from the DVD player (does a basic Tosh/Panny do reasonable bass management?)
Use the crossover-thing on the plate amp made for stereo receivers.
What do you recommend?

 

[Mark Larson]

Can you tell me which software you use for these speaker parameters and where to download it from?

 

[Dave Poehlman]

I've just been using ISD Online while I am sitting here at "work". But you can download their freeware WINISD for Windows if you like.

 

[Mark Larson]

Dave, what do you think about putting the old SVS driver in there? I presume its a 12", and i can get it for a fair bit cheaper than the Dayton.
I assume it is built for a larger enclosure though, right??
Please tell me the answer to this as well...

Another thing: i don't have a surround receiver yet, so i have two options:
Use a sub cable from the DVD player (does a basic Tosh/Panny do reasonable bass management?)
Use the crossover-thing on the plate amp made for stereo receivers.
What do you recommend?

 

[Dave Poehlman]

The old SVS would work very well sealed in that size box with maybe 1.5lbs of fiberfill.. pretty solid down to 50 Hz.
It's pretty much a toss up if you use it ported in that box... you don't gain much in extension... and you'd lose the transient response benefits of a sealed box.
You should get a pretty tight sound out of it.. provided the enclosure is solid and airtight.

Another thing: i don't have a surround receiver yet, so i have two options:
Use a sub cable from the DVD player (does a basic Tosh/Panny do reasonable bass management?)
Use the crossover-thing on the plate amp made for stereo receivers.

Personally, I would use the active crossover on the plate amp in a 2-channel setup. That way you have more control over the X-over point.
What sort/size mains do you have?

 

[Mark Larson]

The old SVS would work very well sealed in that size box with maybe 1.5lbs of fiberfill.. pretty solid down to 50 Hz.

Only to 50 hz ??? :frowning: :frowning: :frowning:
I was expecting till something like 30 hz.

 

[Dave Poehlman]

Well, 50Hz is just where is starts to slope off at 6db per octave. So, at 30Hz you're down about 6db.
Oh, it'll play 30Hz... and you'll hear it... it'll just be a little quieter than at 50Hz.
Here's the curve:

The pink line is the sealed enclosure.. the yellow is if you kept the port as is. As you can see, there is a hump just before the rolloff.. that'll contribute to a "boomy" sound.
You could always try it with the port first and see how you like it. You have the luxury of already having the port in place and filling it in later.