as labs
Member
First time posting, hello!
My goal here is to track a diy project and get some feedback for this unusual speaker, the B&W Matrix 2, that I picked up on marketplace a couple years ago.
Some essentials:
I paid very little money because the tweeters were not working (so I've never heard these speakers in their original, working form). The boxes are in good shape and my plan at the time was to gut them and reuse the nice enclosures for a totally new speaker, probably using the scanspeak 22w and 10f discovery drivers that I have had lying around. I enjoy vintage speaker "reimagining" projects... All this back story is to say that I'm not married to the original design.
original crossover for reference... "tested 1986," love it...
complete with funky protection circuit, all pass circuit, and a couple HUGE inductors and capacitors for impedance flattening...
here's my dilemma:
The 8" poly woofer (jazzed up with some sort of mineral compound) has some unusually linear midrange performance.
Measured on axis, 1m from the baffle, with and without the original crossover.
All measurements shown have 1/6 oct smoothing, no windowing. <200Hz is not to be trusted.
An 8" driver, linear to 6kHz, apparently was crossed over >3k! huh?? It also seems to be living quite happily in this enclosure (no surprise).
Would it be a shame to take this driver out of its happy home? I do imagine the 22w will do well, but then what will I do with the B&W original? [Obviously keep it on a shelf for a decade]
I'm thinking now that I have 3 options:
I was impatient and got to fitting a new tweeter and making a quick crossover.
I landed at 2kHz LR4, so a bit lower than stock. This was the lowest I could get the Kartesian Twt28 to behave; the faceplate mounting holes just happened to fit precisely with the B&W enclosure, the dome+surround diameter too. Some foam for a gasket and my very temporary modeling clay filler were good enough to clean up a nasty dip ~8kHz, so the clay stays for now. And we're listening....
Sum in green, 30 deg off-axis in grey.
The 30deg off-axis response is better than I would have thought for the 8" woofer. I had assumed that 1600 would be falling off axis.
I suspect the diffraction peak at 1k is made worse by the close measurement range (limited time today). It is slightly better in my initial 1m measurements.
Let's see how the woofer is behaving off-axis, sans crossover... getting my ghetto-spin-o-rama going:
Wow! Seems that I'll have to adjust the low pass filter q as this is a very smooth midrange driver and is not losing much energy at 60 deg off axis at 2kHz and below.
ghetto-spinner for reference (it's a plant stand, and no, it's not great...)
testing crossover on the tool bag (pretty simple!)
Now I'm at an impasse... i was excited to use the 10f in a three way, but now subjective listening has been positive in the test configuration... maybe i need to get the other side going and see what they can do in stereo...
Here we have it....
Any thoughts are welcome, bring the opinions!
My goal here is to track a diy project and get some feedback for this unusual speaker, the B&W Matrix 2, that I picked up on marketplace a couple years ago.
Some essentials:
- 8" poly midwoof + 1" poly dome
- sealed box (est. 32L) with a lot of internal bracing and foam damping material. expect to use with a sub for full extension.
- not sure exactly where the crossover was (if there was any overlap in the original design, for example), but the original low pass seems to be quite high ~3.5k Hz (see below)
- rated 87dB efficiency (not verified)
I paid very little money because the tweeters were not working (so I've never heard these speakers in their original, working form). The boxes are in good shape and my plan at the time was to gut them and reuse the nice enclosures for a totally new speaker, probably using the scanspeak 22w and 10f discovery drivers that I have had lying around. I enjoy vintage speaker "reimagining" projects... All this back story is to say that I'm not married to the original design.
original crossover for reference... "tested 1986," love it...
complete with funky protection circuit, all pass circuit, and a couple HUGE inductors and capacitors for impedance flattening...
here's my dilemma:
The 8" poly woofer (jazzed up with some sort of mineral compound) has some unusually linear midrange performance.
Measured on axis, 1m from the baffle, with and without the original crossover.
All measurements shown have 1/6 oct smoothing, no windowing. <200Hz is not to be trusted.
An 8" driver, linear to 6kHz, apparently was crossed over >3k! huh?? It also seems to be living quite happily in this enclosure (no surprise).
Would it be a shame to take this driver out of its happy home? I do imagine the 22w will do well, but then what will I do with the B&W original? [Obviously keep it on a shelf for a decade]
I'm thinking now that I have 3 options:
- "Restore" to an interpretation of the original design (single tweeter, maybe a new crossover point). call it a day and get back to my job, wife, kid, terrible yard, etc...
- Stick with my original plan and build into the box, potentially permanently altering past the point of restoration (scary, eek!)
- OR... combine the two, using the SS 10f in the original tweeter location and add a new "B&W-esque" style tweeter on the top of the enclosure. I may at least try this out before going full gut.
I was impatient and got to fitting a new tweeter and making a quick crossover.
I landed at 2kHz LR4, so a bit lower than stock. This was the lowest I could get the Kartesian Twt28 to behave; the faceplate mounting holes just happened to fit precisely with the B&W enclosure, the dome+surround diameter too. Some foam for a gasket and my very temporary modeling clay filler were good enough to clean up a nasty dip ~8kHz, so the clay stays for now. And we're listening....
Sum in green, 30 deg off-axis in grey.
The 30deg off-axis response is better than I would have thought for the 8" woofer. I had assumed that 1600 would be falling off axis.
I suspect the diffraction peak at 1k is made worse by the close measurement range (limited time today). It is slightly better in my initial 1m measurements.
Let's see how the woofer is behaving off-axis, sans crossover... getting my ghetto-spin-o-rama going:
Wow! Seems that I'll have to adjust the low pass filter q as this is a very smooth midrange driver and is not losing much energy at 60 deg off axis at 2kHz and below.
ghetto-spinner for reference (it's a plant stand, and no, it's not great...)
testing crossover on the tool bag (pretty simple!)
Now I'm at an impasse... i was excited to use the 10f in a three way, but now subjective listening has been positive in the test configuration... maybe i need to get the other side going and see what they can do in stereo...
Here we have it....
Any thoughts are welcome, bring the opinions!