Dirt cheap Heavy Duty 18" PA driver, MCM 55-2994, likely weak motor? Still good value
Hello to all of the DIY enthusiasts and acoustical Big Brains!!
Ok , some Heavy duty cast frame 18s are on clearance right now and if you apply the coupon code (EMC398) it discounts them further to $49!
HOLY GOATS!! WHAT A SCREAMING DEAL!!! right???
Well sort of yes, but you wont be getting exactly what is shown on the website, and i will explain ...
I am already familiar with the 299X series of MCM woofers a while back when i bought a bunch of the 12s (55-2992) from this series, they were on clearance at the time .... You can see my review of them here .... My review is the wordy one of course
MCM Audio Select Heavy Duty Die Cast 12'' Woofer - 350W RMS | 55-2992 (552992) | MCM Audio Select
If you read the review you will see that the measured parameters do not match the published parameters and MCM is notorious for this exact problem with many of their house brand drivers .... We could assume that their original sample driver (which the published specs were derived from) had a stronger motor than the production drivers, it sure seems like someone is cutting corners .....
A weaker motor is probably due to an overly wide gap or a lower grade ferrite material used in the magnet, and results in higher QES/QTS figures and a lower BL figure ...
The LE and RE figures matched up well enough with published numbers, but suspension was very tight so VAS figures were low in turn pushing the FS higher up which was actually not necessarily a bad thing if you are planning to load these into a custom designed TL , QWP cabinet or Tapped Pipe / Transflex (Or ML-Transflex) ....... However with this lack in motor strength you can expect that the cabinet will need to be large in order to get optimal performance from these drivers ......
A good friend of mine, Pete, who lives nearby took these off of my hands and mounted 4 of them (55-2992s) into a huge homebrew ML-TL cabinet and this monster box actually sounds AMAZING!!! It is surprising at how much bottom end his 4x12 box can produce without needing to be pushed very hard .... High QTS drivers can surprise you if used in the right cabinet such as Quarter wave (eigenmode) TL and pipe cabinets .... So luckily my story had a happy ending even though i was unable to use them in the compact cabinets I had planned for them. I am really glad that Pete was able to make something truly awesome out of them
So i just wanted to be sure that folks had proper warning before I post this link and draw attention to this bargain ... It really is a very good deal as long as you understand that when it comes to T/S parameters MCM's truth in advertising leaves a lot to be desired ....... Also i would not advise ordering these 18s unless you have a way to get them tested in order to obtain the measured figures which will be necessary to design a proper cabinet ...................... I use a Dayton DATS unit (a product which i love dearly) to test my drivers ......
Here is the link to the model 2994 18s with the coupon code embedded:
MCM Audio Select Heavy Duty Die Cast 18'' Woofer - 500W RMS | 55-2994 (552994) | MCM Audio Select
Hello to all of the DIY enthusiasts and acoustical Big Brains!!
Ok , some Heavy duty cast frame 18s are on clearance right now and if you apply the coupon code (EMC398) it discounts them further to $49!
HOLY GOATS!! WHAT A SCREAMING DEAL!!! right???
Well sort of yes, but you wont be getting exactly what is shown on the website, and i will explain ...
I am already familiar with the 299X series of MCM woofers a while back when i bought a bunch of the 12s (55-2992) from this series, they were on clearance at the time .... You can see my review of them here .... My review is the wordy one of course
MCM Audio Select Heavy Duty Die Cast 12'' Woofer - 350W RMS | 55-2992 (552992) | MCM Audio Select
If you read the review you will see that the measured parameters do not match the published parameters and MCM is notorious for this exact problem with many of their house brand drivers .... We could assume that their original sample driver (which the published specs were derived from) had a stronger motor than the production drivers, it sure seems like someone is cutting corners .....
A weaker motor is probably due to an overly wide gap or a lower grade ferrite material used in the magnet, and results in higher QES/QTS figures and a lower BL figure ...
The LE and RE figures matched up well enough with published numbers, but suspension was very tight so VAS figures were low in turn pushing the FS higher up which was actually not necessarily a bad thing if you are planning to load these into a custom designed TL , QWP cabinet or Tapped Pipe / Transflex (Or ML-Transflex) ....... However with this lack in motor strength you can expect that the cabinet will need to be large in order to get optimal performance from these drivers ......
A good friend of mine, Pete, who lives nearby took these off of my hands and mounted 4 of them (55-2992s) into a huge homebrew ML-TL cabinet and this monster box actually sounds AMAZING!!! It is surprising at how much bottom end his 4x12 box can produce without needing to be pushed very hard .... High QTS drivers can surprise you if used in the right cabinet such as Quarter wave (eigenmode) TL and pipe cabinets .... So luckily my story had a happy ending even though i was unable to use them in the compact cabinets I had planned for them. I am really glad that Pete was able to make something truly awesome out of them
So i just wanted to be sure that folks had proper warning before I post this link and draw attention to this bargain ... It really is a very good deal as long as you understand that when it comes to T/S parameters MCM's truth in advertising leaves a lot to be desired ....... Also i would not advise ordering these 18s unless you have a way to get them tested in order to obtain the measured figures which will be necessary to design a proper cabinet ...................... I use a Dayton DATS unit (a product which i love dearly) to test my drivers ......
Here is the link to the model 2994 18s with the coupon code embedded:
MCM Audio Select Heavy Duty Die Cast 18'' Woofer - 500W RMS | 55-2994 (552994) | MCM Audio Select
Matthew, nice to see I am not the only bottom dweller... I owe you huge thanks for the LAB15-4 SR! Using it in my Keystone Lite to good effect.
Found this post in a recent recent search for MCM reviews. Mind if I ask your opinion of the MCM 55-2963? MCM Audio Select 15'' Die Cast Woofer with Paper Cone and Cloth Surround - 200W RMS 8ohm | 55-2963 (552963) | MCM Audio Select Looking to throw a pair of 15s in these recently acquired bass horns in this thread: http://www.diyaudio.com/forums/subwoofers/275639-id-mid-horn.html These are going into the HT/music listening area and no PA use. I know the MCM drivers TS are suspect but curious if I might get away with it in these horns as they are basically reflex.
Found this post in a recent recent search for MCM reviews. Mind if I ask your opinion of the MCM 55-2963? MCM Audio Select 15'' Die Cast Woofer with Paper Cone and Cloth Surround - 200W RMS 8ohm | 55-2963 (552963) | MCM Audio Select Looking to throw a pair of 15s in these recently acquired bass horns in this thread: http://www.diyaudio.com/forums/subwoofers/275639-id-mid-horn.html These are going into the HT/music listening area and no PA use. I know the MCM drivers TS are suspect but curious if I might get away with it in these horns as they are basically reflex.
Lab15-4 (sr) GREAT STUFF!! =D
Zwiller,
I am really glad that the Lab15-4 (special run) worked out for you!
I really love the parameters on that particular driver, they made it easy for me to come up with some really simple to build, compact quarter wave designs with decent output.... That Lab15-4 driver is such a great deal! ..... Last time i checked they had just just popped back up on ebay , and that was recently so they may still be available ....
Zwiller, Out of curiosity i have to ask: did you happen to do any break-in on that driver outside of the cabinet? If so did you notice any problems with mechanical noise coming from the motor or was it reasonably quiet?
I am not at all familiar with the 55-2963, I wonder if anyone here on DIYaudio has measured that model? It would be nice to know what sort of parameters can really be expected from them ..
Zwiller,
I am really glad that the Lab15-4 (special run) worked out for you!
I really love the parameters on that particular driver, they made it easy for me to come up with some really simple to build, compact quarter wave designs with decent output
.... That Lab15-4 driver is such a great deal! ..... Last time i checked they had just just popped back up on ebay , and that was recently so they may still be available ....Zwiller, Out of curiosity i have to ask: did you happen to do any break-in on that driver outside of the cabinet? If so did you notice any problems with mechanical noise coming from the motor or was it reasonably quiet?
I am not at all familiar with the 55-2963, I wonder if anyone here on DIYaudio has measured that model? It would be nice to know what sort of parameters can really be expected from them ..
*nod*
Zero D,
Right ....
People will need to be equipped to measure these and should expect to design a box around some pretty high QES/QTS figures, otherwise (if a person is unable to do these things) i would not suggest buying these ......
Based upon my experiences with other MCM drivers (even some from this series) it would not surprise me at all to know that the actual QTS of these 2994s ends up being in the .7 to .9 range ...
I just really wish that MCM would just pull their heads out of their /\$$es and get with the program, fix the issues with their OEM and insist upon higher grade ferrite, then publish the real parameters on their website ......... A little truth in advertising is not too much to ask for ....
You would think they would be at least a little concerned for their reputation...
Zero D,
Right ....
People will need to be equipped to measure these and should expect to design a box around some pretty high QES/QTS figures, otherwise (if a person is unable to do these things) i would not suggest buying these ......
Based upon my experiences with other MCM drivers (even some from this series) it would not surprise me at all to know that the actual QTS of these 2994s ends up being in the .7 to .9 range ...
I just really wish that MCM would just pull their heads out of their /\$$es and get with the program, fix the issues with their OEM and insist upon higher grade ferrite, then publish the real parameters on their website ......... A little truth in advertising is not too much to ask for ....
You would think they would be at least a little concerned for their reputation...
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Pete's 4x12
By the way guys, here are some pictures of Pete's monster 4x12 loaded with my 55-2992s ..... This turned out really well ! Rich and powerful sounding bottom end on this cab,
A high QTS is not the end of the world as long as you have a low enough VAS along with enough motor strength to work with and use it in an alignment that is suitable for higher QTS drivers ... ML-TL was a good choice on Pete's part but not the only option, there are a few other designs that would have been appropriate ..
By the way guys, here are some pictures of Pete's monster 4x12 loaded with my 55-2992s ..... This turned out really well ! Rich and powerful sounding bottom end on this cab,
A high QTS is not the end of the world as long as you have a low enough VAS along with enough motor strength to work with and use it in an alignment that is suitable for higher QTS drivers ... ML-TL was a good choice on Pete's part but not the only option, there are a few other designs that would have been appropriate ..
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I really like the LAB15-4. It simmed really well in most designs I tried. I did not break it in. I contemplated it but wimped out. Never did something like that before and the build with it was my first DIY build besides some sealed car subs from years gone by.
I really wish there was a movement to get some stickies or FAQs here. A standard testing page, folded vs tapped horn info etc, and then maybe we could create a MCM database/page with the DATS data.
Matthew, just how much info can the DATS give? Can it confirm Xmax, WRMS etc?
I really wish there was a movement to get some stickies or FAQs here. A standard testing page, folded vs tapped horn info etc, and then maybe we could create a MCM database/page with the DATS data.
Matthew, just how much info can the DATS give? Can it confirm Xmax, WRMS etc?
Pros and Cons
Derfnofred,
That Infinity is said to be a decent driver, some DIY guys have had good luck with them
Compared to the MCM 2994 I cannot say which one would be better or worse it really just depends on the application since these two drivers are such different animals ... Even though we don't know the exact parameters for the 2994 just yet, i can with confidence still summarize some basic pros and cons for you ...
So anyway, it all depends on your application really and what it is you are trying to accomplish ....
;4375046 said:
Derfnofred,
That Infinity is said to be a decent driver, some DIY guys have had good luck with them
Compared to the MCM 2994 I cannot say which one would be better or worse it really just depends on the application since these two drivers are such different animals ... Even though we don't know the exact parameters for the 2994 just yet, i can with confidence still summarize some basic pros and cons for you ...
- The Infinity can be used in a small box and could be incredibly portable/convenient, but the 2994 will require a relatively large box with the benefit of more output at the same drive level (higher efficiency) ...
- The Infiinity has twice the excursion capability but the 2994 makes up for it with twice the cone area..
- The 2994 says it has 500w rms power handling (but who knows , after all this is MCM we are talking about) versus Infinity's 300w rms rating ...
- The FS figure (free-air resonance) of the Infinity is very low at 23hz so if you plan on tuning the cabinet much higher than that you will want a good high pass filter (or subsonic filter) set up to prevent the driver's cone deflection from getting entirely out of control and physically damaging the driver below your box's FB (fundamental tuning frequency) ............. The 2994 on the other is a very different story with it's FS of over 40hz and tight suspension.... It has been my experience that MCM drivers often have an even higher FS than their published figure....
So anyway, it all depends on your application really and what it is you are trying to accomplish ....
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Zwiller,
I think a database with measured T/S parameters from off-brand drivers like MCM would be fantastic! It would really reduce the riskiness of buying budget drivers since people would have a better idea of what they are actually getting, instead of ordering something and discovering it is crap then having to go through the hassle of sending it back or the disappointment of eating the loss...
It is not designed to measure Xmax or WRMS because of the very small signal it uses but the DATS unit gives me everything else i need to simulate some designs until i find something that works for the particular driver ...
with caution- I bought 6 peices of a MCM driver based on another customers measurements posted in a review, the ones I got were not even close, much weaker magnet, so beware, maybe later batch was from different source. When they do list parameters they never match , a database would be interesting
Just to throw a wrench into things - since someone mentioned car subs - I thought I would point out that but Eminence is blowing out their 15" Eminator 2515 sub for (ready?) $34.50 shipped.
I am building a ported box for one that will go into my buddy's car. Should be fun (it is sure priced right). I think it was close to $100, pre-sale.
I am building a ported box for one that will go into my buddy's car. Should be fun (it is sure priced right). I think it was close to $100, pre-sale.
Yeah, I'm a big fan of tinkering with 'el cheapo' drivers as there's usually a lot of bang/buck if big cabs isn't an impediment, so with MCM and some others no longer around, I'd always assume Qts was at least 2x published and before T/S there was a formula to find the 'optimum' net cab Vb based on a driver's Fs in and out of a sealed box, then tune to Fs or whatever performs best overall in the intended app.
GM
Foam surrounds make me feel uneasy .... I have seen too many rotted foam surrounds .... but supposedly the newer formulations last longer (or so i have heard) ...
I hope the 1506 and 1508 model Eminators will go on clearance , they have the treated cloth accordion surrounds
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