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MCM 55-5660
So perusing the new KB line from MCM got me interested in some of the smaller diameter models, the 5" in particular. It looks like it has an underhung coil which, with the copper cap, should provide a very nice distortion profile.
On the other hand, advertised Qts is fairly high and the gap is fairly short, which might limit it to pure midrange or fairly limited extension usage - so...
When I read the ad-copy, I feel they are targeting Dayton's Reference series and what I see is an improved basket (the Dayton's lack under spider venting), copper in the motor (on the RS180 at least, there is no copper - the only shorting device is the phase plug itself), and of course the underhung voice coil - although I have heard compelling arguments in both directions for the benefits/drawbacks of such a thing. For now, I'll just ask this question:
"Do you think this driver has the potential to be a high end midrange in a large 3-way?"
I love the Taiga tower speakers, listen to them every day in fact, but I feel the itch for a new set of towers building up - and a thread over at "the other place" started by someone who really has issues with understanding certain aspects of DIY and associated costing got me to thinking...
This particular driver has an impressively flat impedance profile, and although at first blush the response curve looks goofy that broad depression between ~400 and ~1500 will actually be a benefit when installed in a cabinet. Within the expected pass band, the response is smooth - if not flat.
Rumor has it that the KB series is showing up at MCM today - so sometime next week I will have a pair of the 3" and a pair of the 6.5" in-hand and will do some testing. The 6.5" are not mine to keep, but if the testing goes well I will purchase a pair of the 5" and test those.
For the proposed (purely theoretical at the moment) high-end, ignore individual driver cost and focus on performance 3-way I think the best tweeter choice will be the Viawave ribbon, or if something cooler comes out in the meantime along the lines of ribbon drivers - I'll use those. I have been listening to the RS28A this week, and although it is a kickass tweeter - I guess I just prefer ribbons these days. There, I said it.
For shoring up the bottom end - I will wait for results on the 6.5". If the T/S indicate reasonable extension (under 45Hz F3) and the advertised 7.5mm Xmax holds up under scrutiny they should offer some serious bang for the buck performance as well. Bonus is that the overall footprint and aesthetics would probably end up very similar to Taiga (although Taiga has an F3 of 33Hz).
Geoff, I would once again like to thank you for steering MCM in this direction. PE is a great company, but they have stood alone for too long in the world of in-house branded, high value drivers. I love having options in these price ranges.
On the other hand, advertised Qts is fairly high and the gap is fairly short, which might limit it to pure midrange or fairly limited extension usage - so...
When I read the ad-copy, I feel they are targeting Dayton's Reference series and what I see is an improved basket (the Dayton's lack under spider venting), copper in the motor (on the RS180 at least, there is no copper - the only shorting device is the phase plug itself), and of course the underhung voice coil - although I have heard compelling arguments in both directions for the benefits/drawbacks of such a thing. For now, I'll just ask this question:
"Do you think this driver has the potential to be a high end midrange in a large 3-way?"
I love the Taiga tower speakers, listen to them every day in fact, but I feel the itch for a new set of towers building up - and a thread over at "the other place" started by someone who really has issues with understanding certain aspects of DIY and associated costing got me to thinking...
This particular driver has an impressively flat impedance profile, and although at first blush the response curve looks goofy that broad depression between ~400 and ~1500 will actually be a benefit when installed in a cabinet. Within the expected pass band, the response is smooth - if not flat.
Rumor has it that the KB series is showing up at MCM today - so sometime next week I will have a pair of the 3" and a pair of the 6.5" in-hand and will do some testing. The 6.5" are not mine to keep, but if the testing goes well I will purchase a pair of the 5" and test those.
For the proposed (purely theoretical at the moment) high-end, ignore individual driver cost and focus on performance 3-way I think the best tweeter choice will be the Viawave ribbon, or if something cooler comes out in the meantime along the lines of ribbon drivers - I'll use those. I have been listening to the RS28A this week, and although it is a kickass tweeter - I guess I just prefer ribbons these days. There, I said it.
For shoring up the bottom end - I will wait for results on the 6.5". If the T/S indicate reasonable extension (under 45Hz F3) and the advertised 7.5mm Xmax holds up under scrutiny they should offer some serious bang for the buck performance as well. Bonus is that the overall footprint and aesthetics would probably end up very similar to Taiga (although Taiga has an F3 of 33Hz).
Geoff, I would once again like to thank you for steering MCM in this direction. PE is a great company, but they have stood alone for too long in the world of in-house branded, high value drivers. I love having options in these price ranges.
I have a signature.
Comments
Our goal was to design something that everyone would see and immediately have projects running through their mind. I personally have my eyes set on the 8"
We are trying to get our line to take off, and everything you guys are doing helps us. We want to make great drivers that are affordable to everyone, and we seem to be doing alright so far
Thank your for the praise, and the topic starter.
Best Regards,
Geoff Schneider
Here is a picture of the conditions. ARTA @ 4in.
Next impedance and phase overlap
DATS of #1.
DATS of #2.
#1 FR & distortion.
#2 FR & distortion.
Enjoy.
I bought a pair of these MCM 55-5660 drivers from Johnny this past weekend in Iowa. Thanks JR for the smokin deal!!!
Anyway I had a chance today to do a thorough inspection of these drivers and measure them with DATS. So after that I fully agree with Johnny:
- the frame is very nice, much more elegant than the RS150P's clean but simplistic frame. Under spider venting takes it to another level IMHO.
- the kevlar/paper mix cone is every bit as nice as the Dayton RS paper series. Same conical profile, almost the same Mms. The RS has a higher Mms probably due to its longer voice coil (over-hung design).
- flexing the suspension exposes a copper ring on the pole piece!
- the glue lines are very clean and consistant.
- polished phase plug (extended pole piece). It looks nice but I will probably knock it out and anodize it black, then reinstall it.
- DATs measured T/S parameters are spot on.
- the biggest difference between this driver and the RS series is the under-hung design. This yields a very limited Xmax but I suspect better distortion performance. This driver would be a huge disappointment if you were expecting any bass performance. But if you deploy this driver as a dedicated mid it should perform stellar. I will be trying this driver as an OB mid in a 3 way, crossed over at 200 Hz or higher.
Jason, I've seen some Klippel reports that reveal Bl and Kms induced distortion well before Xmax and some that look good well after Xmax. Some underhung and some overhung and some stark differences even within a line of drivers (i.e. the 5" driver will underperform its Xmax while the 7" driver outperforms it). I don't know what all the variables are that produce these differences, but generally, the underhung coils have pretty broad, flat Bl curves that fall off rapidly after some point. It wouldn't surprise me if these KB drivers have a good 4-5mm of low distortion excursion before hitting a wall.
Dan
So I decided I regret getting rid of those mids and bought a pair off of Ebay for $14 shipped... They had them listed at $19.99/make offer apiece with $12 shipping so I offered $15. He countered at $1/ea plus shipping! I assume he made a mistake, but I grabbed them anyways. I want to try them as a mid in a 3-way, just looking around for a woofer now. Maybe those 10" "Scanspeak" XXLS woofers that were part of the Aerial buyout. Couple with a nice tweeter and they would make a killer studio monitor in a W/TM format. Maybe that is exactly what I'll do. If I use the Dayton little waveguides it should work.
I forgot what nice build quality these have.
@jr@mac you do anything with those mids yet? I still have my pair I picked up off @PWRRYD two InDIYana events ago. Happened to pull them off the shelf today kicking around an idea to use them as a mid for InDIYana 2024 Theme build. That was until these things modeled as wanting 0.9 cuft in a sealed cabinet! That's a fair bit more than I had budgeted for it. Drivers shown below: Rival R176-PN-08 poly/mica cone with silver dustcap, MCM 55-5660, and GRS RT1.0. I mean I could probably push that Rival up to 3K for a crossover, but I'm not sure I'd want to. Decisions Decisions.
Have not done anything yet, still deciding. They are very nice drivers and deserve some love.
If you're going to be using them as a midrange they definitely don't need that large of a sealed enclosure. Crossing them around 500 Hz in a sealed box of 4 - 5 Liters would be great. Don't worry about seeing a Qtc of 1.4+ that only describes the behaviour around Fb and you'd be operating a full 2 octaves above that. Line the box to absorb the back wave but don't stuff the crap out of it. You want air space behind the cone.
Thanks Craig. That reminder about Qtc only mattering around Fb is a good one. That puts the driver well into contention for my Vb budget on InDIYana rules. Of course, I'm assuming 1.5 cuft for the total enclosure / all ways, not just 1.5 cufut for the low frequency only.
That is my understanding of the rules.
Correct!
As long as you are far enough above the high Q peak, you should be good with using a smaller volume, and yes, keep some open air in there if possible. A tangent, I've found dual chamber sealed volumes for mids to help with the high Q peak, tame the resonance, and yield great sounding mids.
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Do you have any suggested volume ratio's for the 2 sealed but connected mid-driver chambers, Wolf?
I don't know that ratios matter much in terms of sound, but as long as the Fs magnitude is reduced, it tends to be beneficial in multiple ways. Xover becomes easier to implement without having the resonance stick out or need to be dealt with, and the driver just does not sound hindered or muffled.
I used a 1:1 in the BarGain, and had the front lightly stuffed and the rear lined only. I used a pegboard and foam ice cream sandwich as the barrier between the chambers, the foam was lightly compressed.
I did it again on the Bottleships mid chamber. The volumes appear to be 1/3 and 2/3, but the damping across the dividing line really looks to essentially divide the chamber in half.
According to lore surrounding the MAPD alignment, the front chamber is 1/3 Vas, and the rear chamber is = to Vas. In reference to what I've done and what worked for others, 1:2 to 1:1 to 2:1 is likely where I would stay.
InDIYana Event Website
I tried googling but came up empty. What's the MAPD alignment?
Just taking a wild guess... midrange aperiodically damped ^shrugging shoulders^
I don't know what it means, but...Multi-chamber Aperiodic Progressive Damping
That's probably closer.
McIntosh apple pie dish
Multichamber APeriodic Damping, a term coined by Northcreek.
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