MCM 55-3190 build quality review ($20 cast frame 8")

[johnnyrichards]

This guy is on a clearance price of $20.

The cone is a very attractive dark gray (bordering on black) poly, with a soft dustcap of a slightly different shade. The cone is not particularly stiff, but no softer than most poly drivers I have looked at in the past.

The surround is 1/2" round rubber, very supple and soft. It is glued over the top of the cone, and along the back side of the attachment point it appears a damping material has been applied.

The frame is cast, as advertised. However, it uses a more traditional styling to it which is why there is also a gasket on the front. This gasket is soft foam, and appears to be easily removable if determined to be too ugly. Old school drivers like this are generally a love it or hate it for me. In this case, I like how the look works. The gasket material is one piece and is not cardboard that goes a long way to creating a less ugly driver.

Turning the driver over reveals no under dustcap or under spider venting, but there is a vent on the back plate. There is no bumping on the back plate, but there isn't on the Dayton Reference series, either so I don't know what to think about that. With only a little over 3mm of Xmax, the uglies may kick in before the VC starts hammering into the back plate.

The spider is about 5" in diameter, the VC looks to be about 1.5" and the tinsel leads are not insulated and may become troublesome at higher excursions. There are several ways to prevent that - one being not to drive woofers to floppy levels.

The entire frame is painted black, and offers somewhat more breathing room than a typical stamped frame, but it otherwise resembles typical stamped frame drivers. Imagine a typical stamped frame woofer, and then imagine it made of cast aluminum with knockouts on the spokes. The individual spokes are well reinforced, however, so frame flexing will be kept to a minimum. It appears very strong.

The motor looks pretty typical of this price class, with a die stamped top and bottom plate and ceramic magnet.

The terminals are the typical .205" (positive) and .110"(negative) and have some type of gold plating on them. They seem to be heavier gauge than some other drivers in this price range, so the .110" might give you some grief if you use push on terminals like I do.

Over all, based strictly on build quality this driver is well worth the clearance price of $20 and if the parameters are as advertised, would make a fine anchor to a budget 3-way in a small(ish) enclosure. Think 1 cubic foot tuned to the low 40's...

On another note, MCM has repeatedly demonstrated that heavy cast frames are not an obstacle to producing entry level priced drivers. It makes me wonder when Dayton Audio will revamp or replace the DC/DA/DS lines.

[Mark65]

Nice review, Johnny! Sorry I bugged out early last night, but life got in the way.

In regard to the last note, I'm not sure which I'd rather see: A cast frame DA, or a paper/poly/nomex/kevlar (pick your poison) cone RS.



Can't wait to see your listening impressions and measurements.


Mark

[BeeTL]

Funny...I was looking at this one earlier today.

[B_Rich]

the uglies may kick in before the VC starts hammering into the back plate.

Don't know why but I found this phrase quite humorous lol.

Good review Johnny, very detailed. So much that even a beginner such as myself could follow along very easily

[michiganpat]

response looks like it would be decent in a mid-sized/big 2 way like the classic EPI M100, boston A70, AR 4x, etc....

I'd like to find those gaskets. I could use a couple pair for my AR18's, and the woofers used a single piece foam gasket on them, which fell apart when I refoamed them.

[johnnyrichards]

Nice review, Johnny! Sorry I bugged out early last night, but life got in the way.

In regard to the last note, I'm not sure which I'd rather see: A cast frame DA, or a paper/poly/nomex/kevlar (pick your poison) cone RS.



Can't wait to see your listening impressions and measurements.


Mark

The cast frame DA is already available, they are just called MCM Audio Select Seriously though, the cast frame, aluminum cone drivers from MCM are all pretty nice - usually.

[arlis_1957@yahoo.com]

thanks john. i look forward to your mesured fr and listening impressions.
wondering if they would be worth for the bottom of a mtmww with the peerless 830875.

[tedwilt]

Bass response pretty poor. $5 gets you more here http://www.parts-express.com/pe/show...number=299-284
Pretty is as pretty does.
Ted

[johnnyrichards]

I don't know about that, Ted. Here is 1 cubic foot for each, the 8" vented and tuned to 42 hz, and the 10" sealed:



Here is 2 cubes, again the 8" is vented and the 10" is sealed:



Here is the 10" in an alignment that finally equals or exceeds the 8" (five cubic feet, tuned to 30Hz):



I'll take the 8" every day, the only way I am eating up five cubic feet is if there are at least two 12" drivers with a kilowatt driving them

[tedwilt]

Sami 10 Nearfield 2V large open baffle tests Steps with uncompensated
Microphone. probably would be higher spl if calibrated. Microphone preamp adjusted below clipping.

Hz .... dB
24.90 129.571
29.66 131.678
40.28 134.871
50.54 136.773
60.06 137.804
70.68 138.561
80.57 139.116
89.72 139.139
99.98 138.649
110.23 138.779
594.73 138.139

Show me some real open baffle tests instead of box simulation hehe
Ted

[johnnyrichards]

130db @ 25 hz? What is TC Sounds doing wrong

[johnnyrichards]

Wait - near field? What does it look like at, say, 1 meter?

[johnnyrichards]

Or in something like a box, even? Something is screwy with your measurements and they are not really any better than box modeling.

[tedwilt]

Hey I explained the high dB reading was caused by my adjustment of the microphone preamp to give best SN without clipping although the 10" Sami is the most efficient speaker I own. Full range listening confirms the high efficiency (but not pro level). Tests were made with my made up baffle constructed of several 1" thick particle boards fastened to heavy industrial shelves. Baffle is 49" wide and 92" tall. Not ideal because of shelves and not perfect location. Near field is only thing possible because of numerous reflections. I have not tested them in a tiny sealed baffle because I have no intention of building such a little speaker.

Test the 8" with Steps with large open baffle (test baffle). Absolute dB level not important to show response depth and smoothness.
Which do you suppose would give the best output on open baffle. Four of these Samis or one 8"?

Hey Johnny you are the king of buyout bargains, give me a chance.
Ted

[johnnyrichards]

It's apples and oranges, really.

[tedwilt]

http://s187.photobucket.com/albums/x193/ted4412wilt/

[johnnyrichards]

Yeah, I was trying to get apples to apples, you were going dollar to dollar

[johnnyrichards]

Just broke in and measured one unit on LIMP

Factory specs follows:

Fs: 35

Qes: 0.440

Qms: 1.920

Qts: 0.358

Vas: 2.01 cubic feet


My measured specs:

Fs: 31.63

Qes: 0.445

Qms: 1.906

Qts: 0.361

Vas: 2.31 cubic feet

So, slightly larger box but slightly better extension. Looking real good for a slim floorstanding TMW

[BeeTL]

Looking real good for a slim floorstanding TMW

There's an audience out there for 3-way systems if you can get the crossovers and drivers to play nice.

[ontariomaximus]

JR, any more thoughts on the MCM 8"? I am thinking of getting a pair for a TMW's. Box would be 1.1ft3 tuned to 38hz. Or closed box 0.8 ft3, F3=66hz F10=37hz qtc = .707