[nfafan]

Hello all,

Have a pair of old Fisher STV-889A and and a pair of Fisher STV-724 floor-standing 3-way bass reflex speakers. Love the go big/go home air about them and want them working "better".

That is, they "work" - as in all 3 drivers in all 4 speakers (which for the most part appear to be the identical speakers amongst all, just different cabinets...) produce sound and are room-shaking capable; but it's just that most of the time it sounds like the woofer is doing all the heavy lifting. At lower volumes they aren't much.

I haven't torn into any of them yet, but from research - they don't have any have much in the way of semi-serious cross-overs installed to speak of.

Enter this:

http://www.ebay.com/itm/1-PASSIVE-3...709?pt=LH_DefaultDomain_0&hash=item5b08ec5045

I was wondering if this would help the speakers out, given that they apparently have little as it is anyway.

So - does anyone have any experience in using these or any pre-assembled cross-overs in old speakers?

Thanks in advance for the help!

 

[Face2]

Generic crossovers are a disservice to the DIY and should be avoided.

 

[wvu80]

Edit: I backtracked on my bad advice putting good money after bad.

 

[Woodfiend]

If you want to do it just to experiment it could be a fun learning experience.

But you would have the same luck as buying clothes off the internet sight unseen without looking at the colors/sizes/style (parameters). When you go to try them on.... they probably won't match and may be too tight up top and baggy and sloppy down low. Both the clothes and the generic crossover probably won't model well....................

 

[Five28]

I have a pair of old Bose 501's from the late 70's. They look nice but never sounded all that good. I "thought" they sounded good when I bought them but I was an audio noob at the time and believed the Bose marketing. Over the years the foam surrounds have dry rotted and instead of having the surrounds replaced, I thought that eventually I would take the drivers out (a 10" woofer and two 1" tweeters) and replace them with real speakers from a respected manufacturer. When I was originally thinking about this project I thought that I would buy a car audio component speaker set from MB Quart, which includes a crossover designed for them, along with a 10" subwoofer. I have a pair of the MB Quarts in my car and they sound excellent. Still haven't gotten around to actually following through on this project though. The problem is that by the time I buy a pair of 10" subs, and two sets of component speakers I will have invested more than just buying a new pair of good sounding, decent speakers. Probably not worth the effort. In my opinion, I don't think a generic crossover is going to help much and may actually make the speakers sound worse. The crossover needs to be designed based on the frequency response of the individual drivers. Lastly, I have never heard a speaker made by Fisher that sounded good. No highs and boomy, muddy bass.

 

[nfafan]

Thanks all for the replies!

Basically I got an entire "early 90's vintage" Fisher Studio Standard set up - rack, recvr, tuner, dual deck, 5 CD changer, turntable, the 4 speakers - free for hauling them away. Price was right.

So while the speakers work, I want to make them sound a bit better. Couldn't imagine they didn't sound somewhat decent when new, else who would have been buying these things..

Will circle back once I tear into these and see what the internals look like.

 

[mobeer4don]

Good chance that replacing the 20 year old electrolytic caps will help...and that should cost a good bit less than $17.

Yes, by all means rip into them and check out the build quality.

 

[A9X-308]

I know the consensus is against generic XO's, but a crossover for $17? How can you go wrong?

$17 wasted dollars.

 

[head_unit]

A random crossover could randomly sound great, but much more likely make the sound worse. Take it from me, I'm a loudspeaker engineer.

You should open it up and take pictures to post here, especially of the components. Most likely there are just series capacitors feeding the midrange and tweeter, and nothing on the woofer. Replacing those old caps may improve the sound.

What will definitely improve the sound is stuffing the speakers. 1 lb fiberglass per cubic foot is a starting point. Better details and materials can be found at places like Madisound Speaker Components, and in
http://www.amazon.com/Loudspeaker-Design-Cookbook-Vance-Dickason/dp/1882580338
where he has a whole section about it. The main point is to absorb midrange to keep it from re-radiating through the thin enclosure walls.

Then, damp the enclosure walls. Madisound or Parts Express have stuff; I once used auto body undercoat which worked decently albeit smelly.

Then, stick bracing in the cabinets. Dowels or chopped 1x1s cut to slightly force fit side-to-side, top-to-bottom, front-to-back.

Doing those three things absolutely transformed some very similar old speakers owned by a friend's husband. I was quite shocked.

THEN, get some member here or at DIYAudio.com or etc. who has a measurement setup to take some measurements for you. You can then commence to design a REAL crossover for these babies.

 

[freekmccoy]

Me2

I'm thinking the same thing,I have a pair of Fisher STV-9635 that I'd like to do the same with.

 

[wvu80]

Let me jump in here to backtrack, to agree with others.

I was under the impression there was something wrong with the old XO's, and in that case I was thinking new XO's would not hurt. I fully agree it is doubtful you take rip the XO's out of a speaker that doesn't sound good to begin with and plug in new random XO's that musical nirvana would ensue.

My apologies for the bad advice.

 

[manuetdeo]

a random crossover could randomly sound great, but much more likely make the sound worse. Take it from me, i'm a loudspeaker engineer.

You should open it up and take pictures to post here, especially of the components. Most likely there are just series capacitors feeding the midrange and tweeter, and nothing on the woofer. Replacing those old caps may improve the sound.

What will definitely improve the sound is stuffing the speakers. 1 lb fiberglass per cubic foot is a starting point. Better details and materials can be found at places like madisound speaker components, and in
http://www.amazon.com/loudspeaker-design-cookbook-vance-dickason/dp/1882580338
where he has a whole section about it. The main point is to absorb midrange to keep it from re-radiating through the thin enclosure walls.

Then, damp the enclosure walls. Madisound or parts express have stuff; i once used auto body undercoat which worked decently albeit smelly.

Then, stick bracing in the cabinets. Dowels or chopped 1x1s cut to slightly force fit side-to-side, top-to-bottom, front-to-back.

Doing those three things absolutely transformed some very similar old speakers owned by a friend's husband. I was quite shocked.

Then, get some member here or at diyaudio.com or etc. Who has a measurement setup to take some measurements for you. You can then commence to design a real crossover for these babies.

^this

 

[nfafan]

OK, haven't torn into them yet, but per the original books that came with all the components, the speaker booklet has the schematic of the x-over. Basically a couple caps and a couple resistors and a fuse. No mention of any other components - like an induction coil(s). I will mull over the schematics and come back with "details". May have to take a cellphone pic of the page as I have no scanner.

It is this simplicity that made me wonder if a proper 3-way turnkey x-over was of any improvement from what is hiding in these mid-80's speakers. Well, that and possibly missing bracing, acoustic foam.

 

[Jay1]

OK, haven't torn into them yet, but per the original books that came with all the components, the speaker booklet has the schematic of the x-over. Basically a couple caps and a couple resistors and a fuse. No mention of any other components - like an induction coil(s). I will mull over the schematics and come back with "details". May have to take a cellphone pic of the page as I have no scanner.

It is this simplicity that made me wonder if a proper 3-way turnkey x-over was of any improvement from what is hiding in these mid-80's speakers. Well, that and possibly missing bracing, acoustic foam.

Most of these old school speakers were designed around the natural driver roll offs. This is how they get away with simple 1st order electric high pass crossovers. Usually the mids/woofers are run full range on top as the drivers have fully dampened breakups with natural 2nd order acoustic roll offs.

Until you measure and design it's all a crap shoot.

 

[nfafan]

STV-724 crossover pics... I tore into one of the STV-724s as it was more convenient than getting into an 889A - and the only diff is the 2" shorter cabinet of the 724 from the 889A.

The Culver 175A-50 is a fuse or breaker.

Another view: 2 Culver caps; small one is 1.5uf +/- 20% 100VDC, larger Culver cap is 6.8uf +/- 20% 100VDC

And another... two resistors

So now I wonder if the Parts Express 3-way turnkey x-over would be a good choice...
The speaker cabinet had almost so bracing, and zero dampening materials of ANY kind.
The mid and tweets are both sealed backs and marked Fisher and made in Korea. The woofer was made in Japan.

 

[mobeer4don]

Do you now get the feeling that $17 was more than was spent to build the entire speaker? Much effort went into making that speaker sound acceptable at absolute minimum cost.

 

[nfafan]

Do you now get the feeling that $17 was more than was spent to build the entire speaker? Much effort went into making that speaker sound acceptable at absolute minimum cost.

So far I'm out a whopping $20.00 bucks in wood and glue to add bracing. I'll toss in some more on mattress topper and cheap pillow-stuffing that can be shared with the 2nd STV-724. So - need to determine if there is a way to improve the crossover without going crazy.

Hindsight is 20/20, but some folks in 1984 must've thought these were decent speakers.

 

[nfafan]

Update; working as time allowed, I added 3/4" x 2" wood bracing inside where zero bracing existed before, definitely got rid of the hollowish wood box sound.

Snagged a new foam mattress topper and cut it up to line three of the 4 internal faces. Used a piece of foam to create a separation shelf at the bass ports between the mid/tweeter upper half and lower half where the woofer lives.
Snagged a new polyfill pillow and added a few handfuls of of the fluff to the area behind the tweeter and mid, above the internal foam "shelf".
The foam and fluff definitely deadened the internal echoes of the braced-box.

Couldn't wait; reassembled and tried again - the full-range 15" woofer still overpowers anything from the mid or tweeter (which work, but can't be heard at all unless the woofer is taken from the circuit.).

Next step in the experiment is to just swap the existing x-over caps and resistors with fresh replacements from PE, which should be under $20.00 to do both speakers.

 

[mobeer4don]

Don't forget to check PE for some ultra-cheap buy-out mids and tweeters. Swapping out parts can be educational regardless of performance (but better performance would be nice).