I just finished the prototype xos and had a first listen. Not too shaby but certainly not on par with higher quality drivers. Actually this is the first time I've heard the ports chuffing before the woofers bottom out. I was at about 90 dB at 10 feet.
I have finalized the crossovers for the Zobellito's. They are pretty smooth and fun to listen to actually. I tried to extract as much detail as I could from the cheapo Dayton TCP115-4 drivers but ultimately their distortion profile determined the total outcome. These speakers don't suck, but I guess I've been spoiled using much better drivers in my other recent projects. Their bass is surprisingly great for two 4 inch $12 drivers in 5 liters. Their midrange is pretty good up to about 90 dB. The top two octaves are very good thanks to the sleeper Dayton ND25FW tweeters.
I just got back to this project today. I did a lot more measurements and lots of voicing today and I think they are now the best I can do with these drivers. I need to build new ports as I can hear the current ones huffing at 90+ dB. I will post all the design details shortly.
Nothing pretty or special here: unwound buyout 3.5 mH 19 gauge inductors for the woofers and diy hand wound 0.1 mH inductors for the tweeters. Otherwise cheap Dayton caps and resistors.
I just rolled a second coat of black Duratex on these plywood enclosures. I flush trimmed them and gave every side a good sanding with 150 grit, but I didn't spend any time trying to hide the joints or the plywood end grain with filler on this project. After all, these are only going to be sitting on the shelf over my basement work bench, driven by a low wattage tube amp, and not in our living room or gifted to someone else, right? Still... it just kind of feels cheap when you can see the seams and end grain of the ply ghosting through the paint job. Thoughts?
Craig, you're too hard on yourself! I'll bet they look better than my DIY monitors for my edit system at work. Now those are really ugly - hacked up, repurposed boxes.
Well I decided to give these one more coat but this time giving them a LOT more texture. I used one of those blue open cell foam rollers that Duratex gives away with their products. It worked of course. I generally like a lot less, like the Keramiskas I brought to Indy, but for a cheap project like this it works.
These are finally completed and sound pretty darn nice. Way better than they should considering all 6 drivers cost less than $83. Good solid bass from those 4 little 4" woofers, clean midrange, and nice highs from my favorite cheap tweeters. Buyout xo components and 1/2" ply keep the total project cost pretty low.
The final enclosures are 6" wide and 6.25" deep, constructed of 1/2" thick plywood with a 3/4" thick removable poplar baffle. The overall height is 15". This leaves a net internal volume of 5 liters. The 40mm ID ports tune the enclosures to 55 Hz.
The crossovers aren't overly complicated. Damped second order electrical on the woofer (looks like first order with a Zobel... hence the name Zobellitos) and a third order electrical on the tweeter with some padding resistors.
Oops... typo! The tweeters are ND25FW, not NE... sorry. And it's hard to see the decimal point on the woofers' inductor. They are 2.5 mH iron core.
Here is the measured frequency response, including the measured reverse null. I normally don't get such a clean measured reverse null. Measurements were taken at 30". Due to my small family room and necessary gating the measurements are only accurate above 600 Hz.
Here is a shot of the crossover boards. When building speakers this small I find it easier to separate the low pass and high pass and fit them on smaller boards.
The overall distortion is pretty good. Certainly not "Revelator" level distortion, but what the heck... these are $12 woofers. The tweeter distortion is quite good considering their cost.
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InDIYana Event Website
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Oh I like that idea Mike. The LP filter is actually damped 2nd order electrical which looks like 1st order with a Zobel.
The Zobellito's it is!
A 4 ohm tmww using the waveguide tweeter, a 4 ohm for the mid, and a pair of the 8 ohm as woofers could be a fun budget bomber.
https://www.harborfreight.com/air-tools/paint/1-12-gallon-gravity-feed-texture-air-spray-gun-60314.html
Perfect, thanks John, I am going to start a new Thread regarding Air Sprayer - need a cheap one.
Oops... typo! The tweeters are ND25FW, not NE... sorry. And it's hard to see the decimal point on the woofers' inductor. They are 2.5 mH iron core.