Those speakers I bought...

[johnnyrichards]

Are, as expected, pretty miserable

On Tweeter Axis, 1M, plus impedance:


Both Units:


Distortion @ 90db:


Waterfall @ 90db:


With and without grill:


Raw Drivers:



Download raw in-box driver data here, if you want to play. If used, remember that no need to enter any offsets into PCD as that is contained in the files.

I'll grab some construction pictures and whatnot here in a bit, as well as offer some commentary on the whole shebang.

[johnnyrichards]

Re: Those speakers I bought...

The cabinet is all 3/8" MDF, wrapped in black woodgrained vinyl. The drivers are both flush mounted. They are actually rather nice looking. The grills fit tight, and flush with the cabinet which means the front baffle is recessed a bit.

Here is a picture of the front of the baffle:


On the backside are some binding posts, and a port. The binding posts are small and none of my nanner's fit tightly into them, but they will also accept bare wire. here is a snapshot:


The woofer is a hard paper cone and dustcap, stamped frame unit. It looks like the cone profile has a curve to it. It has a real rubber surround, and what looks to be a 1" VC.

Here are some pictures of the woofer:




Some parameters:

Re: 6.85

Fs: 118.4

Qm: 4.77

Qe: 2.66

Qt: 1.708

Vas: 0.05 cubic feet

Dd: 3.25"

Here is approximately what the designer tuned the cabinet to:


Yuckers boom boom.

The tweeter is a 1" soft dome, with a generous slug of something soft behind the dome. I could not push the dome in very far before I felt resistance. Looking at the impedance curve, it does not have any ferrofluid. Fs is ~1200 Hz, and the designer used a single 2.2uF capacitor as a crossover. Surprisingly, it is a 100v capacitor, I generally see 50V caps in crap speakers.

Some pictures. Both of the tweeters have uncentered domes:



I believe all internal wiring is about 24awg, but all connections are actually soldered. Cheaper than crimp terminals.

The woofer is a standard 4" frame - the Dayton DA and DS would be a drop in, so will that Peerless on buyout. The tweeter is 2-5/8" diameter, the TB 1166 is one that comes to mind. There are probably others, as well.

The cabinet has no stuffing or lining of any kind, it would be cheap enough to add some polyfil, block the port and add an LPad to the tweeter. A couple braces and I think these would be good enough. As-is, they sound like they measure. Little bright on top, recessed vocals and a thumpity thump. The woofer has maybe 2mm of Xmax and it uses it up pretty fast, it is a very low sensitivity driver. Software calculates it at 82db, and when I measured in REW , it showed ~82-83db @ 2.8V so not a high sensitivity design by any standards.

I am probably going to mod the cabinets, re-use the existing tweeters and add some better woofers. I think the buyout Peerless will be just fine in there. Drop right in, bass tuning and all.

The woofers that came with, will make a much better mid than a woofer, and will find a home along those lines someday.

Time to clean up, order those Peerless woofs before they sell out and take a nap.

[DIYNut42]

Re: Those speakers I bought...

Nice write-up Johnny. Thanks for the update. These OEM re-designs are good stuff to pay attention to for people just starting out. Gives everyone an idea of what not to if you want to design and build your own speakers from scratch, and have them perform to your expectations.

Looking forward to seeing the end result.

[mzisserson]

Re: Those speakers I bought...

Heck man... $25 and you get a set of mids, a set of cabs, and tweeters? Sounds like a value to me. Interesting find and great use of the hobby.

[jhollander]

Re: Those speakers I bought...

Thanks for posting the measurements. That was fun playing around (novices need practice). Not that anyone would but this is what I got with $16 in parts for one. The tweeter polarity is reversed.

[johnnyrichards]

Re: Those speakers I bought...

Thanks for posting the measurements. That was fun playing around (novices need practice). Not that anyone would but this is what I got with $16 in parts for one. The tweeter polarity is reversed.

Hey John, close to what I came up with.



Five components:



Tweeter is reverse polarity as well.

I found the tweeter squawked pretty loudly around Fs, but the L-Pad tames it down.

[johnnyrichards]

Re: Those speakers I bought...

Modeled impedance:



Modeled transfer function:



Adding a Zobel consisting of a 4.7uF and 10ohm resistor to the woofer deepens the reverse null quite a bit more. Probably worth it.

The biggest problem with this system is the woofer Q. Plugging the port helps out a lot.

[kenrhodes]

Re: Those speakers I bought...

cool project i cant wait to see the finished project. Too bad that by the time you put the new xo in their it is the price of a decent set of speakers:http://www.newegg.com/Product/Produc...82E16882117405
I wonder how they would com pair?

[johnnyrichards]

Re: Those speakers I bought...

cool project i cant wait to see the finished project. Too bad that by the time you put the new xo in their it is the price of a decent set of speakers:http://www.newegg.com/Product/Produc...82E16882117405
I wonder how they would com pair?

DIY for the sake of DIY, otherwise I can't believe anyone is building speakers for less than $150/pr these days.

[Ryan]

Re: Those speakers I bought...

The company that made those decided to design a vented enclosure around a driver with a Qts of 1.7!!!:eek:
Keep the updates coming!

[kenrhodes]

Re: Those speakers I bought...

and...:D

[johnnyrichards]

Re: Those speakers I bought...

Sorry, I order everything using Smart Post or whatever the hell that is, so the new woofers ain't here yet

[johnnyrichards]

Re: Those speakers I bought...

Also Ken, my Xover upgrade is only $11/speaker so the price goes to $47/pr from the $25/pr in stock form.

Sadly, though, I have seen these speakers go for $21 on auction. I just made an offer and should have waited

[Taterworks]

Re: Those speakers I bought...

What 'brand' are these speakers? I missed that. They don't exactly look like Klipsch or Polk, or any other major name.

[johnnyrichards]

Re: Those speakers I bought...

What 'brand' are these speakers? I missed that. They don't exactly look like Klipsch or Polk, or any other major name.

"Technical Pro" fo shizzle.