Brainstorming a driver config for a *very* cheap 10" 3-way retrofit

[jim85iroc]

so over the weekend, I may have succumbed to an impulse buy, and came home with 2 dozen speakers. Well, technically 25.



Most of these are cheap MTX AAL 10" "3 way" speakers that are, well, terrible. Most of them I'm going to resell, but I've got a few with bad woofers. My son took an interest to this whole fiasco and we discussed replacing the woofers, but since these sound so bad, I started thinking out loud and we ended up discussing a total upgrade. I don't really have the ambition to do a scratch build, especially considering what MDF costs now, so I want to reuse the cabinets, and would like to make my life even more difficult by trying to avoid enlarging any of the driver cutouts, but I'm flexible on that.

This is what I'm starting with:


Drivers consist of a 10" woofer with a 9.25" cutout, a 5" sealed back midrange with a 4.125" opening, and a horn tweeter with an opening of 2.75".

On a side note, the "crossover" on these is a joke. The woofers play full range, the mids have a single inline cap, as do the tweeters. The output on the mids is so low that you could disconnect them entirely and probably not notice.

My design goals are to have a speaker with a considerably improved sound quality (this won't be difficult - the bar is set very, very low), driver costs under $100 total, and a more pleasing aesthetic. I'm really after a Cerwin Vega party speaker type of sound that sounds good loud and isn't fatiguing. I'm not going to be playing Brahms on these, I'll be playing Metallica.

I'm having a bit of difficulty in selecting drivers. For the woofer I think I've settled on the Dayton Classic 10" (DC250-8). It models reasonably well in this enclosure with an F3 of 38hz and only a very mild bump in output around 50hz, which honestly, is fine with me for this type of speaker.

For the midrange, I'm a bit conflicted. The idea of some of these sealed back mids appeals to me because they're a simple drop-in replacement for the existing hole, but this will either require a notch to get rid of the high Q spike on the low end, or a higher crossover frequency than I'd like. Either way, these won't extend low enough for me to cross the woofer to the mid at the baffle step transition, which would have been ideal. Another option is to suck it up and build a sub enclosure behind the midrange, which opens up the option of using something that can cross down near the 300 baffle step transition range. It also lets me use the 4" paper woofer buyout that PE has for $5.80. Even though this driver is 16 ohm, it looks like the sensitivity is high enough to work with the Dayton Classic woofer. If I build a 5" cube behind the mid opening, I model about a 3dB bump at around 250hz before it rolls off sharply. This should lend itself well to a somewhat simple high pass filter for the mid.

So, if I go with the Dayton woofer and the $6 mid, that leaves me just under $12/each for tweeters, which obviously isn't much. I could go with some variety of the Peerless BC25s, or maybe try out the Apex Jr tweeters that sell for $15/pair. Those have a pretty hot top end, which I think would be a nice book end for the bump that the woofer has at the low end.

For aesthetics, I don't really plan on doing much, but these enclosures are pretty beat and most of them have a bunch of screw holes from various mounting brackets that were installed from their years in bar rooms and other public places. I'm figuring on filling the screw holes and either painting them black or maybe laying a new fresh layer of vinyl wrap.

At this point I'd love to get some general feedback from the collective about the plan. I realize 100% that these aren't going to win any awards for sound quality, but my goal is just to have a fun project with my son, and re-acquaint myself with the overall process of using Soundeasy, designing and implementing some filters before I get back into trying to use up some of the higher quality drivers that I've been sitting on for over a decade.

[cooper]

I would look at the GRS paper woofer. And, a white van to sell them out of

[jim85iroc]

I would look at the GRS paper woofer. And, a white van to sell them out of

I did look at the GRS. They're such a ridiculously high Q that they're going to be even less ideal for these enclosures than the Daytons, and honestly, I hate how the ribbed cones look.

GRS does have the one poly woofer though. I should see how it models in the enclosure. It's a much higher q than the Dayton, but that might give me a nice bump at 45 or 50hz.

[tomzarbo]

And I thought I had a problem.

[fpitas]

I'll be devil's advocate and point out that you can end up spending more overall using very cheap drivers, because the crossover gets more complicated.

[jim85iroc]

Yeah, that's what scared me away from the sealed midranges. The buyout mids look really well behaved with wide bandwidth though, so I should be able to cross to the woofer and the tweeter in their linear regions.

[chrisn]

Your choices of the DC250 , buyout mid, and BC25 seem solid. The DA270 is nice too but destroys the budget.

Whats the Realistic speaker on the left?

[jim85iroc]

I don't remember. It's actually what caught my eye in the original ad. I was hoping it was a Mach 1 or 2, but it's some small 8" 2 way with rotten foam. I would have refoamed if it was a pair.

[LOUT]

If you're thinking about a cheap-ish GRS but want to avoid the accordian look (and their usual low XMAX limits) I think the rubber-surrounded GRS SW10-4 models okay in that box (guessing around 45L...didn't see it mentioned) F3 around 40hz ported or 50hz sealed. BUT I think the DC250 models really similarly for the low-end, and the DC probaby has more accurate T/S params compared to what's given for GRS while only costing about $7 more...similar or higher sensitivity with the DC while keeping 8ohm stable too.

EDIT: duh, that's the "poly GRS woofer" you were already talking about. Might be worth a look if you prefer 4ohm and sealed (assuming its XMAX advantage is real), otherwise I'm guessing the DC would still be better.

[LOUT]

Just realized when you said you're aiming for "driver costs under $100 total" you meant per PAIR rather than per box (after noticing the mention that a ~$30woofer and ~$6mid only leaves around $12 for tweeters). Was originally wondering why things sounded so tight budget-wise while thinking "I don't get it, $20/20/60 for a threeway seems like plenty of room". Makes a lot more sense after pulling my head out, lol.
With that in mind, and the difficulty of reselling, maybe the GRS being a little cheaper might be worth it afterall (assuming 4ohms isn't going to shoot some feet).
Has anyone here tried them to see if their claimed XMAX is anything near reality or if it's a distorted mess?

[hex168]

How about a F.A.S.T. design ("full range and subwoofer technology," or "full-range assisted by woofer" - not my acronym)?

You could use the DA-250-8 and your choice of full-range in a small sub-enclosure. Some candidates: Visaton frs-5x, Tectonic TEBM46C20N-4B BMR, Tymphany TC9-FD18-08 (TC9 may be too low-efficency, depending on how much baffle step compensation you need for where the speakers will be located). If you want to go the lazy way for the sub-enclosure, surface mount the full range driver above the woofer and glue a chinese take-out soup container filled with damping material to the back of the front baffle behind the full-range. Use lots of glue and prep the surface first, a leak would be bad. If you are concerned with the woofer flexing the soup container, nest a couple of them so it is double-walled. Leave the unused old drivers in place,disconnected, to fill their holes. Not state-of-the-art, but won't be bad and will be cheap.

[jim85iroc]

I'm not really sure that fits my design goal. I still want to keep this in that "party speaker" kind of realm, and to me, that's a traditional 3 way design with a nice fletcher-munson curve built in. I'll probably end up using an open backed midrange/midbass driver that will require a dedicated sub enclosure, but I want to utilize a dedicated tweeter, since there's already a hole in the cabinets for one. My hope is that I can use the woofer-mid crossover area as a quick & easy way to integrate the baffle step compensation too.

[jim85iroc]

so last night I remembered that I had a pile of the old Vifa/JBL buyout 4.5" speakers that PE had somewhere around 2004 or 2005. I've got 2 flavors, 299-432 that have foam surrounds, and 299-495 that have rubber surrounds. I used 1 pair of the 495s in a small 2 way that I've been using since. I never used the 432s. I've still got the FRD & ZMA files for them, so they may be worth fooling around with. They fit beautifully into the midrange openings of these cabinets, so they might be a possibility, though I remember those 432s having a notched response that would be perfect in a narrow cabinet to compensate for baffle step losses, but would end up being problematic in these big cabinets, so the 495s might be a better option.

[LOUT]

Sorry in advance for even suggesting this after you JUST SAID that something like this doesn't really fit your design goals (and it might be dumb for distortion reasons too).

If your 2005 buyouts don't work for some reason (or you don't have enough) I think the DC28F-8 would fit and fill that midwoofer hole and meet the DC250 low enough for the XO to double as the BaffleStepComp. I know it's usually recommended to cross it a little higher, but this pairing should only end up pushing this tweeter to about half of its 0.5mm XMAX...so excursion shouldn't be an issue at least for the tweeter.

Skipping the midwoofer XO entirely while also being able to use a simple cap and resistor for the tweeter itself saves an easy $10-20 in XO parts (which helps make up for the slightly more expensive DC28F VS a cheaper midwoofer+tweeter combo).

This used a 22"x14" BaffleStepSim, and the phase/XO summation stays about the same with a woofer Zaxis offset anywhere from 20mm-70mm (one benefit of low XO at least). The far-right sixpack image is showing the dc28F and its XO at ~22.5v (about where the woofer will hit 75watts output).

Once again, I understand this doesn't fit too well with your 3way design goal, but it might be an affordable backup if you run short on some of the midwoofers or if something better doesn't pan out. Just had to mention it after seeing how surpisingly nicely it seemed to model.

EDIT: I'm roughly trying this by listening with the same tweeter and HP but a different woofer and LP. I thought the tweeter was distorting for certain at first, but now I'm wondering how much of it's the amp which I normally don't push nearly this hard.

[jim85iroc]

it's definitely something to consider for a future build, but since these cabinets already have midrange and tweeter cutouts, I'm pretty solid on sticking with a 3 way configuration. I do have a soft spot for 8" 2 ways though, so a modified version of this setup could be an interesting idea for one of those in the future.

[LOUT]

It's pretty hard to argue against a 3way when you already have some nice midwoofers on-hand as well as a really affordable newer buyout option, and the cabinets are already setup for 3way.

I'm curious if anyone has distortion measurements or golden eared hands-on with the DC28F HighPassed this low at this modest output level. [spoiler]I can try it myself (and probably will later today) but I don't have measuring equipement or knowledge and I don't really trust my ears for picking out things like any of the more experienced folk here probably can. I'll still try it just to sate my own curiosity of course, lol.[/spoiler] Mostly off-topic for this thread though.

[jhollander]

Why not measure what you have? Hard to know if you are upgrading without seeing what the current drivers do.

[jim85iroc]

The woofers are blown, and the mids & tweeters are trash. I've listened to some of the other ones that are functional. The woofers aren't bad except that they're playing full range. The mids are so low in output that I think they're just there for show, and the tweeters sound like they don't play anything over 10khz. These were built to look a certain way with absolutely no consideration given to their sound.

[rpb]

How many pairs are you going to upgrade? Can you enlarge the mid-range hole using a router?

[jim85iroc]

I only anticipate upgrading 1 pair. The rest are fully functional with their stock components and I expect to sell them as-is.

I could enlarge the hole if there was a suitable justification, but I'd prefer not because this wood is very cheap particle board and I would prefer not to risk chipout. Plus, I want to run the midrange up to 3khz or so, and a larger mid would start to beam.

[Whitneyville1]

Making a silk purse outta a sow's ear makes the pig mad and doesn't make a very nice purse does it? I feel your pain and understand where you're at. Your $50 limit is realistic and I don't mean Radio Snack, you can't throw money at these forever. Your comparison to some C-V speakers can be pretty valid, loud party speakers that after 3-4 hours don't make your ears bleed. Have you considered a 10" two-way??? I think you'd have to go to $80 a speaker for the woofer and tweeter (skip the mid altogether) but I think you could build a mean two-way in that box. Just an idea...

[jim85iroc]

Tonight I ordered some drivers. I got the Dayton Dc250 woofers, 4 of the buyout mids, and a pair of the Peerless BC25 tweeters. I probably won't use the mids for this project and will probably use those old Vifa buyouts. While I wait for PE to fill the backorder on the tweeters, I can start working on the mid enclosures and stiffening the main enclosures.