MiniDSP + 3-way Paper Cone RS Speakers = Awesome

[danmarx]

I promised myself I wouldn't spam all the forums with this speaker build when I started it, but after getting these things completed (nearly 3 years later) I really just want to showcase how awesome the Dayton Audio RS paper-cone series drivers are and say thanks to Parts Express for supporting my addiction for building low-cost, high-performance DIY speakers. I had always dreamed of building a pair of speakers that fit this basic, yet high-end looking style (kudos to anyone who can guess the inspiration for this project, admittedly it's not too hard) and am super excited to finally get to show them off a little bit. I'm sure this design doesn't suit everyone's taste, but for me it was exactly what I was going for. After listening to them for the first time this past week, I just couldn't help but jump on the forum to share, mainly just from sheer excitement on my part. Plus the wife lost interest in the whole speaker building saga years ago! Anyway, here's the quick rundown/stats on these Dayton RS-based speakers:

• (2) 8" RS225P-8 Paper Cone Woofers
• (1) 7" RS180P-4 Paper Cone Mid-woofer
• (1) 1-1/8" RS28F-4 Silk Dome Tweeter
• 3/4" MDF construction with multiple cross bracing and window bracing
• 1-3/4" front and rear baffles (stacked 3/4" plus 1/4" MDF baffle board for recessed mounting)
• 1/4" birch ply veneer on sides stained Winwax Classic Gray
• Flat spray painted black (front/top/back/bottom) with a satin Polycrilic clear coat
• Lower Cabinet is ~78L and tuned to 32 Hz via 4" Precision Flared Port (represents a BE4 (Bessel) alignment)
• Upper Cabinet is ~30L and is sealed (Qtc = 0.5 overdamped alignment)
• Internal cabinet acoustic treatment is made up of carpet padding, cotton batting and polyester fill
• Active crossover/EQ via pair of MiniDSP 4x2 Kits housed in an old VCR powered by two LM317 linear regulators in series (110Vac-15Vdc-10Vdc-5Vdc)
• Current crossover settings are 200/1800 Hz at 24 dB/octave LR - just to get started, haven't played around too much here
• Emotiva UPA-700 (7) Channel amplifier - (6) channels used
• Total speaker weight - 142 lbs.

That's just a starting point for the basic speaker specs. I haven't spent more than a couple of hours just dialing in some routine crossover/EQ settings with the MiniDSP just so I could start listening. This is my first jump into the world of active DSP so I'm still figuring it out and looking for advice tips on how to get the most out of a setup like this. I'm using REW and a Behringer ECM8000 mic for now and so far with very little tweaking have been able to achieve a more than reasonably flat response in-room and the speakers sound better than I could have imagined. But I've only scratched the surface here.

Anyway, thought I'd share just a few pics of the final product. I've got a whole bunch of build pics too if anyone's interested. Let me know what you think!

Dan

[tomzarbo]

Looks good! I used birch ply on my first few speaker builds to get a nice look and add a bit of heft to the enclosure. They came out nice!
Any construction pics?
TomZ

[Kornbread]

Don't know your level of experience with crossovers, but speaking for me, I find the minidsp so easy to work with even a flying pig could get decent sound with it. But still think it will take someone that really knows what they're doing to get 100% from the minidsp/speaker combo.

Good looking build.

[danmarx]

Thanks! I have lots of build pics. From just sheets of MDF in the car all the way to the end. I can only post 5 pics at a time in the forum though, so here's just a few more.



I have more experience doing passive crossovers, so I'm in awe at the flexibility of the miniDSP. And it is super easy to at least get a basic crossover working and balanced outputs from each driver. I've taken some quick measurements to at least get that far and then I've just been listening to them ever since. I can only echo others when it comes to performance of the RS line of Dayton drivers and that soft dome tweeter has just blown me away. They look great, they sound great and they are affordable drivers. I can't wait to get them broken in a little more to see what they can really do. I'll post some more build pics too.

[andykriech]

Really nice look Dan.
Remind me of Wilson Watt Puppys. Did you just mask off the black from the gray? Very nice and somewhat subtle look to the finish.
I would like to see a picture of the VCR housing the DSPs, too.
Really solid cabinet design. Are you working on hardwood floors? Brave.
Andy.

[danmarx]

Thanks Andy, and you're correct, the design was inspired by Wilson's Watt Puppy. I remember listening to a pair some 15 years ago and thinking that some day I wanted to build a pair just like them. There was something about that look with the two separate cabinets that I just really liked. Plus it made the project a little easier to tackle, since for me it just felt easier to build only the lower cabinet first which is really a simple rectangular box. There's not a whole lot of magic in that enclosure. But the upper cabinet has the non-parallel side walls and the 14° sloped front baffle for time alignment of the mid and tweeter and was just more complex to cut and build. So I was glad to not have to do it as part of the lower cabinet. I basically broke the whole project up into 4 separate enclosures and then spent a good part of just the last year building them. So that is my garage, I put down some cheap laminate flooring because both my daughters dance (tap & ballet) so that space is both workshop and dance studio. Plus it doubles as a home theater on the weekends. I hung a used projector and built an inexpensive 5.1 setup (mostly Craigslist stuff) in there too. Who says a garage is just for cars?

Here's a pic of the miniDSPs in the VCR housing. It's nothing fancy, I just wanted something that looked like stereo gear (albeit retro 90's stereo gear) and was cheap. Not exactly super cool though, but it is functional. I tore apart a junky power supply and then cleaned it up with a pair of LM317 linear regulator kits I bought from Amazon for $2 a piece. I don't have an o-scope so I can't say how clean the DC supply is at the final output, but there's zero hum so I'm happy with it. Also, yes, I stained the birch ply first and got that finish completely done, and then used 3M blue painters tape and newspaper to mask it off while I spray painted everything else. It worked perfectly and left a really clean line between the stain and the paint. The polycrilic clear coat then covered both the birch and the paint in one step to make it look cohesive. I've done this a few times now with speakers and really like the two-tone look, plus the real wood really looks nice in the house and brings a bit of elegance to an otherwise spray painted speaker box.

Dan

[crossbound]

Those look great! love the dark plywood sides. Gives a nice subtle contrast to the black baffle and top! Nicely done

[danmarx]

Thanks! I should have posted this project as I was building it but you guys never would have had the patience to stay interested as long as I spent putting it together. I do want to walk through the tuning/crossover test and measurement technique though with the miniDSP here. I have a plan in mind that seems fairly straightforward. But sometimes what seems obvious isn't always right. Anyway, here's a few more in-process pics.

[danmarx]

Earlier stages of building.....I just noticed these pictures were taken over a year ago. So yeah, I'm probably the biggest slacker/procrastinator when it comes to some projects. They just take too long.

[Balocco]

Very cool. How did you make the transition between the veneered plywood and the MDF baffel? I can't really tell from the pictures.

On your MiniDSP tuning, be sure to experiment with the time delay feature between channels. I spent hours one day trying to get rid of a frequency dip that kept moving from place to place depending on my crossover settings. Turns out the dip was caused by frequency cancellation that was happening because my drivers weren't time aligned. A few clicks of the mouse to add a few milliseconds here and there made a big difference. With the angles you have on your baffels, the right time alignment settings will likely make a world of difference. Good luck with your fine tuning!

[danmarx]

The birch plywood is cut oversized from the overall height/depth of the enclosure and then routered nearly flush to the 3/4" MDF. This leaves the edges of the plywood still exposed. Then a piece of 1/4" MDF (which is also used to flush-mount the drivers) covers the edges of the plywood and covers all the screw holes. So it's a two-part process, the trick is the extra 1/4" piece of MDF to cover the raw plywood edge. Then that edge was routered with a 45° chamfer which makes the seam between the MDF and the birch just single line. I had to fill it and sand it to make it look nice though, it didn't always match up perfectly throughout the length of the sides. Here's a couple of pics that might help show this. It's a pretty simple technique, though it's kind of a pain to do.

I have started the tuning process. It's been a lot of fun! But I have not had a change to mess with the timing. The baffle is sloped such that the tweeter is physically already aligned with the midrange (based on VC locations), so it may not need as much timing correction as a traditional vertical baffle. That was the idea anyway. I'm beginning to realize there's a downside to all this DSP flexibility, knowing when to stop messing! There's just too much to play with. I've saved a bunch of different profiles so far as I dial in "what looks good" but then as I sit back and listen and as weeks go by I'm starting to ask myself, didn't it sound better the last time I listened to this song? What were the crossover settings that time? But it looks better now in the graphs, but maybe it sounded better with the previous settings? Driving myself crazy.

Also just reading up on REW the best I can, that is a very powerful tool. What I can say is these Dayton RS drivers do not need a ton of tailoring. My current setup has the tweeter crossed at 1600 Hz and only two shallow PEQ settings just to flatten it out a smidge and neither EQ is set over 1 dB. The mid is the same, I have a very small 1 dB notch at about 800 Hz, and that's it. I'm trying to keep the fine tuning at a minimum, but so far I haven't needed to get too crazy to get some decent looking plots. In fact the first time I listened to these I just set up a basic 200/1800 filter and that was it and they sounded amazing. These could easily be a fully passive setup without question and could sound great I bet.

[Kornbread]

I'm beginning to realize there's a downside to all this DSP flexibility, knowing when to stop messing! There's just too much to play with. I've saved a bunch of different profiles so far as I dial in "what looks good" but then as I sit back and listen and as weeks go by I'm starting to ask myself, didn't it sound better the last time I listened to this song? What were the crossover settings that time? But it looks better now in the graphs, but maybe it sounded better with the previous settings? Driving myself crazy.

Yes, that has proven to be, and still is an issue I'm dealing with. Don't know what the answer is, but I do wonder if another set of ears would help?

Always wanted a Wilson Watt Puppy. In the first set of pics it looks like there are a lot of close room boundaries, bet they'd really open up in a more open room.

[Squidspeak]

I really like the look of these, that's why I plan on doing something very close but with a slot port. Drivers will be Hi-Vi M8a x 2, M5a x1, Scan Disc. 2604 tweeter.
I will build 2 separate cabs but probably join them permanently after veneering and finishing. Very nice job, did you settle on final settings for DSP ?

[danmarx]

I love the flexibility of the miniDSP and the software is completely functional, but after using it for hours on end I realize that it misses the mark just a bit when it comes to the practical application of actually dialing in and tuning speakers, especially if you're doing it by ear. I would love to see presets, or memory settings built in for quick A/B/C comparisons. I know you can save and load different profiles, but it's too many clicks, it needs to be simpler. Also I wish there were a way to sync all the channels so you can set crossover frequencies across channels with one setting, or change the filter type or rate for all the channels at once. It would be much easier to hear differences back to back if there were better unity between the different channels. And then of course using two 4x2 units means that once I get one speaker done, you have to unplug and plug in the other one to do the other speaker. There's no way I can do any kind of reasonable A/B testing with that much fiddling between settings. I wish you could program both miniDSPs at once. I know you can it with the 8x2 version. It would be cool if they updated the software (or plug-in) to cater a little more to the narcissistic audio nut who just can't decide what he wants and give some options for one-click changes between multiple different settings.

So I'm left interpreting dozens of REW plots looking for good FR/phase/distortion/decay and half the time I don't even know what I'm looking for. I just want to listen to music not stare at graphs! It's funny because this past weekend after I had dialed in some crossover settings (160/1600 Hz, LR), I ran FR plots at 48 dB/octave and 24 dB/octave slopes, with no other change, and at 0.5m the summed plots look identical, yet they sounded totally different. I'm not sure if the higher slopes create different/worse off-axis responses or what, but I definitely did not like the 48 dB slopes, something very unnatural about the sound. I'm sure there's a way to measure it, perhaps the phase plots or distortion plots reveal something? Again, I'm not sure just how to see what I can hear all the time, outside of your basic FR plot.

Squidspeak, that's awesome that you're going to build a similar speaker! I love the design, I don't mind the two cabinets being separate either. Never thought about joining them. But they really can't stand on their own and are meant to be together. The slotted port should look awesome. I thought the big round port looked cool when I first started, but they aren't my favorite, it's just a cheap plastic tube, a slotted port would look a lot cleaner. I have a pair of Hi-Vi Swans M3 speakers that I built years ago with a pair of W6 drivers, F5 mid and the RT1-C tweeter and I love them, to this day they still are one of my favorites. I can easily see this arrangement with those Hi-Vi drivers you've picked out, should look (and sound) killer. Have you started the cabinet design at all? Would love to see what you've got cooked up. Active DSP or passive crossover?

[Sydney]

...So I'm left interpreting dozens of REW plots looking for good FR/phase/distortion/decay and half the time I don't even know what I'm looking for. ... but I definitely did not like the 48 dB slopes, something very unnatural about the sound. I'm sure there's a way to measure it, perhaps the phase plots or distortion plots reveal something? ...

Some related material:

https://www.minidsp.com/applications/advanced-tools/rephase-fir-tool