My elderly father-in-law is quite the music buff, and uses ancient Fisher STV-880 3-way speakers (15" bass driver) with Fisher separates. They sound terrible, but still work.
He's got a fair amount of basic woodworking gear, so I'm wondering, what might be done (economically) to improve these speakers, e.g. keep the cabs but make a new baffle with new drivers + crossover?
They sit right up against the wall which is the only position they can be placed in this room.
Pic - basic chipboard cab with dual front ports, 36" (h) x 18" (w) x 13" (d) so maximally 138 liter volume.
He's got a fair amount of basic woodworking gear, so I'm wondering, what might be done (economically) to improve these speakers, e.g. keep the cabs but make a new baffle with new drivers + crossover?
They sit right up against the wall which is the only position they can be placed in this room.
Pic - basic chipboard cab with dual front ports, 36" (h) x 18" (w) x 13" (d) so maximally 138 liter volume.
Attachments
Could be the crossovers are dried out. Look in there for electrolytic capacitors, the ones with dents on both ends. Those crack the rubber, leak and go way off value after a couple of decades.
If not that, the volume is about right 138 L for a 15" ported cab . If you want to do the electronic work without doing woodworking, then buy a speaker design book and see what you can do with Vas, Fs, Qt of new drivers. I use David B. Weems. Fundamentally every speaker sold in discount or department stores was ****. The white speaker cones with no grill over them was probably the biggest sales feature. People buy speakers & musical instruments with their eyes, not their ears. Fisher was a famous amp & tuner manufacturer of the early 60's. They weren't a famous speaker manufacturer as far as I know, not back then.
Test equipment to measure what you've got or built new is fundamental to the process. Omni microphone, mixer, blue line level input to PC or soundcard to USB of laptop, Test software. Open air field or anechoic indoor sound chamber to test in. (I've got mixer, sound equipped PC, the 3/4 acre field).
Warning, particle board vibrates. People are leaning to 7 layer 3/4 plywood now. Baltic birch they always blab about, but none of that is available at Home Depot or Lowes. I just found out today the 3 sheets of 2'x4'x1/2" MDF I bought are ****, too vibration prone. The 3/4 "sahel" plywood sheet I bought for the front might be salvageable.
If not that, the volume is about right 138 L for a 15" ported cab . If you want to do the electronic work without doing woodworking, then buy a speaker design book and see what you can do with Vas, Fs, Qt of new drivers. I use David B. Weems. Fundamentally every speaker sold in discount or department stores was ****. The white speaker cones with no grill over them was probably the biggest sales feature. People buy speakers & musical instruments with their eyes, not their ears. Fisher was a famous amp & tuner manufacturer of the early 60's. They weren't a famous speaker manufacturer as far as I know, not back then.
Test equipment to measure what you've got or built new is fundamental to the process. Omni microphone, mixer, blue line level input to PC or soundcard to USB of laptop, Test software. Open air field or anechoic indoor sound chamber to test in. (I've got mixer, sound equipped PC, the 3/4 acre field).
Warning, particle board vibrates. People are leaning to 7 layer 3/4 plywood now. Baltic birch they always blab about, but none of that is available at Home Depot or Lowes. I just found out today the 3 sheets of 2'x4'x1/2" MDF I bought are ****, too vibration prone. The 3/4 "sahel" plywood sheet I bought for the front might be salvageable.
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step 1: replace the electrolytics and see how they sound.
Step 2: if step 1 doesn't work, assess the woofers - if OK keep them, they may need re-foaming? then add some bracing to the box, and replace the mid & treble drivers with a full range driver (e.g. Dayton PS95), using a simple 1st order crossover at the baffle step frequency
Step 2: if step 1 doesn't work, assess the woofers - if OK keep them, they may need re-foaming? then add some bracing to the box, and replace the mid & treble drivers with a full range driver (e.g. Dayton PS95), using a simple 1st order crossover at the baffle step frequency
Bafflestep losses would still occur yes, but (as a first approximation) you may only have to adjust the level of the mid-high driver(s) relative to the bass if you set the XO at the bafflestep frequency, rather than having to add in extra response shaping elements to (potentially both branches of the XO) to deal with it.
There are some simple things that can improve them. But i have seen many of these. They use dirt cheap drivers. Woofers usually with small magnets.
The similar size cone mid and tweeter are also comminly seen. XO will be 2 cheap-as-possible electrolytic bipolar caps.
Puzzlekoat the cones. Rewire with better wire (thicker on the bass driver, 24g solid is good for the top), damp the baskets, brace the box. Replace the caps with new polys.
And probably a lot more damping in the box to tame the built-in bass bump. The plastic decorative bezel covers on the mid & tweeter can be lost.
Details have been skipped.
These mods cost vanishing little. I expect you will be surprised how much they change. The changes are all to individual bits and sometimes the combo has issues (tweeter too hot because of the loss of cap ESR, or given it is a weak tweeter it might get better).
dave
The similar size cone mid and tweeter are also comminly seen. XO will be 2 cheap-as-possible electrolytic bipolar caps.
Puzzlekoat the cones. Rewire with better wire (thicker on the bass driver, 24g solid is good for the top), damp the baskets, brace the box. Replace the caps with new polys.
And probably a lot more damping in the box to tame the built-in bass bump. The plastic decorative bezel covers on the mid & tweeter can be lost.
Details have been skipped.
These mods cost vanishing little. I expect you will be surprised how much they change. The changes are all to individual bits and sometimes the combo has issues (tweeter too hot because of the loss of cap ESR, or given it is a weak tweeter it might get better).
dave
Known the limits of that woofer in the cab(technically is excursion barred F3 barred power) there are those cheap (gimme!!) mid and tweet.
Something like a mid - tweet combo like the old Hi-Vi (I saw it on Swap Meet some months ago) would make better.
BTW
Knowing at least a direction to look for the issues in what causes what, usually I end up with a mountain of junk
So basically you can't fight natural obsolescence
Something like a mid - tweet combo like the old Hi-Vi (I saw it on Swap Meet some months ago) would make better.
BTW
Knowing at least a direction to look for the issues in what causes what, usually I end up with a mountain of junk
So basically you can't fight natural obsolescence
So it goes... One idea is to slap the drivers on a baffle or make a frame. Some modifications (much bigger coil for OB eq)
Another one (goes together with previous) is to build a little piece of circuitry which performs a bass bump (a bi-quad...which is meant for woofers in closed boxes, but works for èxtending the lows, and yes, it stresses the suspensions) and play some time with it.
Ok ok, what could be done etc etc.
1-dismount everything
2-don't bother about colors of wires, cut everything!
3-find new tweeters
4-now analyze what you've got : a bunch of drivers, a PCB with strange things on it, some wires with Two! rheostats attached, a box with holes and some stuffing inside (already thrashed? Good) and, oooh! The new tweeters arrived! Gee, they cost a lot but they are super technology, best available-state-of-art!
5-wow, new tweeters... Umbelievable! Now, someone on the Net advised me to thrash the old ones. Now I've got these drivers around but I don't know what to do.
Yes, I'm building a pyramidal cab for the woofer but the things get harder as the guy said to put the mid and tweeter outside of the cab, but how? I'm lost
1-dismount everything
2-don't bother about colors of wires, cut everything!
3-find new tweeters
4-now analyze what you've got : a bunch of drivers, a PCB with strange things on it, some wires with Two! rheostats attached, a box with holes and some stuffing inside (already thrashed? Good) and, oooh! The new tweeters arrived! Gee, they cost a lot but they are super technology, best available-state-of-art!
5-wow, new tweeters... Umbelievable! Now, someone on the Net advised me to thrash the old ones. Now I've got these drivers around but I don't know what to do.
Yes, I'm building a pyramidal cab for the woofer but the things get harder as the guy said to put the mid and tweeter outside of the cab, but how? I'm lost