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- rjj45 10:38AM
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Get familiar with the reaction system: Introducing the Reaction System
Edited: "Maggie", an MCM based compact 3-way
Over the past two days, I soldered up the crossovers. The layout changed from the picture I posted in the winter plans thread.
The open space on the bottom right of each board was reserved for the padding resistor - experience has taught me that the tweeter padding needs to be determined after most of the crossover is assembled and the various test leads are removed in favor of the shortest possible hookup leads.
After taking some additional measurements with the crossover outside of the box, I picked the last resistor and finished the crossovers up. Here is a picture of one installed in the cabinet. The pine block is used to secure the crossover.
One speaker is assembled completely, I will throw the second one together this afternoon and take my usual group of measurements. I did not glue the port together yet, sometimes I find raising the tuning a bit after everything comes together is needed.
Should be completed Wednesday. Now I need a name - I have been referring to them internally as the Krimson Kabinet and Krossover Killers but that name does not roll off my tongue so I am now trying to figure out an actual name for them. Will update. Off to work, a VFD exploded.
The open space on the bottom right of each board was reserved for the padding resistor - experience has taught me that the tweeter padding needs to be determined after most of the crossover is assembled and the various test leads are removed in favor of the shortest possible hookup leads.
After taking some additional measurements with the crossover outside of the box, I picked the last resistor and finished the crossovers up. Here is a picture of one installed in the cabinet. The pine block is used to secure the crossover.
One speaker is assembled completely, I will throw the second one together this afternoon and take my usual group of measurements. I did not glue the port together yet, sometimes I find raising the tuning a bit after everything comes together is needed.
Should be completed Wednesday. Now I need a name - I have been referring to them internally as the Krimson Kabinet and Krossover Killers but that name does not roll off my tongue so I am now trying to figure out an actual name for them. Will update. Off to work, a VFD exploded.
I have a signature.
Comments
What's up with the cabinet lining, JR?
What about "Skyfire"? Glows like a warm sunset and sound pretty too?
Resistors are generic silicone coated wire wounds from China.
Anyways:
Modeled on-axis and reverse null:
This shows my preferred spectral tilt and the more-or-less 2nd order nature of the individual driver roll-offs. Crossover points are approximately 600 and 3200.
And here we have the modeled impedance, more or less accurate above 30Hz. Pay no mind to what looks like a high pass filter on the woofer.
I kept it pretty much within +/-45 degrees and it could probably be considered a 6 ohm speaker. Not as toobey friendly as some of my other work, but I do not expect these to be built by anyone else, much less someone with toobz on tap.
As you can see, MCM needs to re-evaluate the cone on the KB series 6.5". Fairly disappointed with the linear distortion, and in the 2-way I did with these a while back I really had to hammer it into submission. Otherwise, the driver seems fine. Lots of excursion on-tap. Hint: ditch the hard paper dustcap in favor of poly or soft treated cloth. I suspect that will help fix that ugly shelf.
The midrange is eerily similar to the Dayton Audio PS95. Annoying hump in the response that remains on-axis, and required a notch filter to deal with it. It is installed into a cup which is attached to the baffle, I documented that elsewhere - probably on that winter plans thread. I like the tonal balance of this driver once the screech was removed from the top end and the hump was hammered down. Probably the best driver in this particular speaker, to be honest.
The tweeter is the cheapest driver in the group - and the only one without a cast aluminum something or a copper ring something. Without breaking one open to find out, I am suspicious of the large rear chamber on this tweeter. There is a high Q bump in the response on the bottom end, and the Fs is not particularly low. However, the impedance curve is smooth indicating good attention to the rear wave of the tweeter. This is not a bad little performer, actually. The grill is removable if that is your thing, and the anodizing is not ugly. I would prefer to see it anodized in black or gray, but this isn't bad at all. As you can see, I took advantage of the naturally falling response of the tweeter to play into my overall spectral tilt. Sometimes you gotta do it.
And the crossover. Other than the notch on the midrange, pretty basic stuff here.
I am probably going to stay home most of the day from work because I am sick, so I might get measurements posted etc, and explore why my bass model does not match reality.
Oh - and the name is the diminutive for "Magdalene", my gramma on my mothers side. She came over from Ireland as a girl, a staunch Irish Catholic. RIP Gramma.
Distortion, 1M, SPL accurate. I think the woofer cone still needs work, but it is otherwise pretty clean with primarily 2nd order dominant. Below 200-300Hz is not to be trusted:
Here is the gated response over impedance. The spectral tilt in the model is not as pronounced in the real world - which is why I never commit to soldering that last resistor until I am as close to done as possible:
Something I usually don't share, but here is a zoomed in impulse response. Read into what you will:
Here is the actual impedance with phase. Other than a mild blip below 45 degrees around 80Hz, it is fairly benign as far as that goes. What are the rules this week for impedance profiles?
And some whorizontals. Little bit of bunching, but my polar measuring technique is not what I would call robust. I only take them and show them to give an idea of what is happening around my head when I listen to them.
OK I have a effin big mess to clean up and I am still not feeling too good, so I am off like a prom dress. You guys have a good night!
These are really very nice sounding. Totally digging them. I know after months of work on a pair, etc, I am always still wondering if I am going to be happy with the results two days later. There has to be a quitting point, though, and when I am going through multiple iterations involving 1uF or 0.1mH I am at the point where I need to button it up.
Part list, as built. Not an inexpensive option at ~$500/pr but you do get a LOT of speaker for the money. Of course considerable cost be shaved by not futzing with knock-down cabinets, using terminal cups instead of binding posts, and substituting NPE caps for the the larger values, and skimping on the finish. I buy my resistors from China these days since they seem to want to sell me every value under the sun.
Feel free to substitute your favorite brand of capacitor/coil - although I do not think you will find a better value in coils than Parts Express house brand these days. If I wasn't committed to an all red crossover, I would have used some of the hoarded surplus caps and coils I have floating around. I am weird like that.
Alright guys, going to fire up the Autocad next and make a baffle layout drawing.
Mrs JR exploring Maggie... Nice...
My wife ran into someone looking for a set of speakers at Stuff this morning and gave him my number. I invited him over for a listen and after a good two hours of jamming and auditioning, we came to a deal on my set of Maggies. It came down to either these or the Swan 3-way modded kit. Because of the little dust cap dent on the woofer, I made him a helluva deal. Man, they sure sounded great on Steely Dan, Fleetwood Mac and Sloop John B by the Beach Boys. The guy really knew music but not so much about audio innards. In the end I also sold him an SMSL amp. It's not what I had on the agenda today, but a good day nonetheless. Goodbye Maggies!
Pretty cool looking at all the people in this old thread.
That's a blast from the past! I always enjoyed the Maggies and often regret getting rid of them. Have to make room, though.