On some speakers the foam on the woofer decomposes over time. No need to replace the driver--you can either have it repaired, or do the job yourself. There are kits on eBay and Amazon for most popular speakers with foam surrounds. The kit contains the foam surround needed to repair the speaker, adhesive, and instructions.
I lucked into a pair of Dahlquist DQM-9 speakers, nearly free. They were not an inexpensive speaker back in the day, but also were not top of the line either. The speaker uses Magnat drivers from Germany; rumor has it that Magnat may have made the entire system for Dahlquist. The Dahlquist company became popular for their model DQ-10 time-aligned loudspeaker array, and are still a collectible to this day.
The DQM-9 is your basic three-way system, with two ports facing rearward for cabinet tuning.
The foam was of course half rotted away. Clockwise from top left are the four steps I took for the project. The first was the original condition--the rubber was there, but the lightest touch makes it fall apart. Second, the basket and cone after the old surround was removed, and the gluing surfaces cleaned up. Third is with the foam glued to the cone, and the fourth is the completed driver. The foam may look a bit wavy here, but that flattens out as the adhesive cures.
I lucked out--Simply Speakers provided the foam surround, and it is a perfect, exact fit. (Some had complained they needed to trim the foam to fit. Because it was a perfect fit, I did not need to worry about aligning the loose cone--I matched to the existing circumference on the woofer (where the old surround was glued).
The cabinets are not in the greatest shape--they cleaned up OK. The grille on one side was cracked on the diagonal corners--I need to reglue it and add reinforcements to fix. The aluminum trim is also a bit pitted in places--I wanted to see the outcome of the project before doing any heavy cleaning or restoration. The front baffle of the speaker is a black velvet material to cut sonic reflections.
Back when I heard the DQM series in the mid 1980s, I remember the vocals had a chesty character to them. I figured the cabinet needed an internal brace. When I had the woofer off, I noticed that the bottom half of the cabinet had no stuffing in it at all. I added some polyester batting to the cavity before reassembling.
The results came out well! Surprisingly strong bass in these cabinets. They image wonderfully. I need to tweak placement in the room. A future improvement (aside from cosmetics) will be to replace the capacitors in the crossovers, as they are 30+ years old (with a lifespan of maybe 20 years--they drift away from their original value over time, due to breakdown inside the capacitor). I might also add a felt circle around the outside of the tweeter, as I've seen on some systems.
So, aside from the other issues, it's easy to re-foam a speaker which has a rotted foam surround. Some speakers use a rubber surround, but many used foam. If you can visually see the foam is starting to rot (it'll develop a crack, or a chunk may be missing), or if you feel the bass is weaker than you remember it and you hear a rattling noise, then your foam is likely shot. It's around $25 for the kit, or a repair shop that specializes in this can refoam them for an affordable fee.
I lucked into a pair of Dahlquist DQM-9 speakers, nearly free. They were not an inexpensive speaker back in the day, but also were not top of the line either. The speaker uses Magnat drivers from Germany; rumor has it that Magnat may have made the entire system for Dahlquist. The Dahlquist company became popular for their model DQ-10 time-aligned loudspeaker array, and are still a collectible to this day.
The DQM-9 is your basic three-way system, with two ports facing rearward for cabinet tuning.
The foam was of course half rotted away. Clockwise from top left are the four steps I took for the project. The first was the original condition--the rubber was there, but the lightest touch makes it fall apart. Second, the basket and cone after the old surround was removed, and the gluing surfaces cleaned up. Third is with the foam glued to the cone, and the fourth is the completed driver. The foam may look a bit wavy here, but that flattens out as the adhesive cures.
I lucked out--Simply Speakers provided the foam surround, and it is a perfect, exact fit. (Some had complained they needed to trim the foam to fit. Because it was a perfect fit, I did not need to worry about aligning the loose cone--I matched to the existing circumference on the woofer (where the old surround was glued).
The cabinets are not in the greatest shape--they cleaned up OK. The grille on one side was cracked on the diagonal corners--I need to reglue it and add reinforcements to fix. The aluminum trim is also a bit pitted in places--I wanted to see the outcome of the project before doing any heavy cleaning or restoration. The front baffle of the speaker is a black velvet material to cut sonic reflections.
Back when I heard the DQM series in the mid 1980s, I remember the vocals had a chesty character to them. I figured the cabinet needed an internal brace. When I had the woofer off, I noticed that the bottom half of the cabinet had no stuffing in it at all. I added some polyester batting to the cavity before reassembling.
The results came out well! Surprisingly strong bass in these cabinets. They image wonderfully. I need to tweak placement in the room. A future improvement (aside from cosmetics) will be to replace the capacitors in the crossovers, as they are 30+ years old (with a lifespan of maybe 20 years--they drift away from their original value over time, due to breakdown inside the capacitor). I might also add a felt circle around the outside of the tweeter, as I've seen on some systems.
So, aside from the other issues, it's easy to re-foam a speaker which has a rotted foam surround. Some speakers use a rubber surround, but many used foam. If you can visually see the foam is starting to rot (it'll develop a crack, or a chunk may be missing), or if you feel the bass is weaker than you remember it and you hear a rattling noise, then your foam is likely shot. It's around $25 for the kit, or a repair shop that specializes in this can refoam them for an affordable fee.
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