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follow-up to speaker project: SUCCESS! - deckeda - 02-21-2022
https://forums.macresource.com/read.php?1,2714893
Lowe's had something like pine hardwood at about $5 for a small board. An oak alternative felt a little stiffer but the pine was stiff enough and 1/3 the cost. No one had any marine plywood. Held up great. I used a spade bit to make partial holes for the flat-bottom mounting bolts.
Starting from a corner, I only had to make 2 cuts. Unfortunately, my 10" chop saw wasn't big enough to cut all the way on the long end and making the completion cut was pretty janky. In respect I should have just used a jigsaw to finish, but from more than a foot away you'd not notice. I used a fine-tooth blade and didn't bother to sand.
Here's a comparison with the original plastic tweeter plate (tweeter removed), below. The original tweeter mounted from behind, attaching at those 4 small holes, with just the dome peeking through in the middle hole. Most soft dome tweeters are like this, albeit with round mounts or wave guides etc. The paint is visually a match, textured black spray paint.
So that ugly gash of a hole in my replacement above means the replacement tweeter had to be mounted in front of the mount plate I made and that hole is huge because the magnet assembly would have to fit through it ... I started with a 3.5" hole saw, but the hole was about 1/8" too small, hence the hatchet job on the hole but no one will ever see that.
I looked into the possibly of removing the new tweeter's factory mounting plate and mounting it from behind --- my original plan --- but the seller said don't do that or you'll void the warranty. If I had the spare cash I'd have tried this, because with only a few new small holes drilled I could have reused the original plastic mounts.
The other issue is that a dome tweeter's mounting plate secures the tweeter assembly together: It keeps the protective metal screen on, the dome and therefore the voicemail aligned and the ferrofluid intact. No need to risk any of that going wrong.
Re: follow-up to speaker project: SUCCESS! - deckeda - 02-21-2022
These are Epos ES14, new they were something like $1100 or $1400/pr in the 1980s and 1990s. I paid $750 used, at a dealer as part of a trade in back in 1999 and then they went into storage for many years. The new tweeters are Peerless Corundum: https://www.parts-express.com/Peerless-DA25TX00-08-1-Corundum-Dome-Tweeter-264-1676?quantity=2
I'd searched several makers and found it hard to find general specs I wanted. The decision tree sort of went like this:
1) I knew the speakers (as original) were not only nominally 8ohms but that overall they never dipped below 7.2ohms. This is somewhat rare. Most "8ohm" speakers have a dip somewhere in the spectrum, possibly so low that they'll still freak out many amplifiers or make them sound not great by throwing a wrench into making some frequency go wonky.
2) I knew the speakers (as original) had reasonably good efficiency, so that if (worse can) the new tweeter played too loud, a simple resister would fix that. If I'd chosen a low efficiency tweeter, I'd be forced to put a large resister on the woofer and I didn't want to go there.
3) I wanted the flexibility to choose the crossover point. Poor tweeters can't play low. I wanted to be able to cross them low if needed, in case a sophisticated crossover needed to be designed (by someone else, not me.)
The only reason I took this project on is because the original design used one capacitor for a crossover. That's it. The woofer is designed to run full range, rolling off naturally up top. Over the lifespan of these speakers, Epos either used a 3.3 microfarad, or a 2.4 microfarad, or a 2.2 microfarad capacitor on the tweeter. (As the woofer kept getting better with each generation that allowed it to run higher up in its range.) Some owners claim the later ES14 sound worse than the originals but whatever.
I'm using 2.7 microfarad, mostly because of a purchasing mistake, but since this design is now all an experiment, it's a good starting point.
I first tackled the defective tweeter and put on some music. The highs in the speaker were now restored and were not very different in level from the other speaker. And seemed decently matched. Promising! So I swapped out the tweeter in the other one and I gotta say they now sound pretty great, and better than I ever remember. I got very lucky with this, even though my crossover point is likely not ideal.
Original:
(painted ... the veneer wasn't great)
Updated:
Yes the new tweeter overlaps the cabinet frame and woofer frame. Don't care. Yes the tweeter dome is technically too far forward (oh noes, its bad for time alignment). Don't care. It works well. I cleaned up the sawdust around the mounting bolts after that shot was taken.
Re: follow-up to speaker project: SUCCESS! - deckeda - 02-21-2022
What changed:
Well for one thing I no longer need to be seated to listen. The originals acted like old tweeters act: You stand up and the highs disappear like a point source. These now have wider dispersion (smoother) while still offering a decent soundstage. They still don't have a ton of depth, but that's most any box speaker.
Re: follow-up to speaker project: SUCCESS! - decay - 02-21-2022
Looks great! Love when a project works out.
Re: follow-up to speaker project: SUCCESS! - Spiff - 02-21-2022
That is awesome. Thanks for the blow by blow! Or, uhhh, tweet by tweet, as it were.
Re: follow-up to speaker project: SUCCESS! - lost in space - 02-21-2022
I have a question. Are those mugshots in the background?
Re: follow-up to speaker project: SUCCESS! - deckeda - 02-21-2022
lost in space wrote:
I have a question. Are those mugshots in the background?
I grabbed a quick background, this LP jacket: https://shop.falseidols.org/release/243510-lonely-guest-lonely-guest
Re: follow-up to speaker project: SUCCESS! - August West - 02-21-2022
It's been many years, but I can say I built the first surrounds for my kit, matching them to higher end nearfield monitors. I see that Speaker City is still around; they were a go to for sound professionals back in the day and I got my drivers from them.
Re: follow-up to speaker project: SUCCESS! - Yoyodyne ArtWorks - 02-21-2022
Congrats, Robin Marshall would be proud!
Re: follow-up to speaker project: SUCCESS! - mrbigstuff - 02-21-2022
August West wrote:
It's been many years, but I can say I built the first surrounds for my kit, matching them to higher end nearfield monitors. I see that Speaker City is still around; they were a go to for sound professionals back in the day and I got my drivers from them.
I've looking for that place! Wasn't it called something else back in the day (20 yrs ago)? The speaker page?