BillFitzmaurice.info

Before you read any further I know that for the most part
However...
I am in a very unique situation where I can acquire these drivers for roughly the same price as the Lab12s but I have to think that with 102db/w/m effenciancy and a down to 17Hz response (because of cab?) these will work better for 4 duel 12" T60s. (I cant find detailed specs anywhere...)

http://cgi.ebay.com/200611642182#ht_1314wt_905

The speaker these are from is a Mackie HRS 120 I work for a Mackie repair shop so I can get Mackie drivers on the cheap + we have 20 of these in stock. if they are comparible / better then the LAB12s for the same price I would like to snag them^^

Without T/S specs, it's a no-go. Since they are described as low-mid drivers, I'm confidant in saying they are not better than the Lab12s.

Armchair Pirate wrote:I cant find detailed specs anywhere..

Then what makes you think they would work?

I don't know where you got the low/mid part as everything I can find says its low. I was also wrong about the 17Hz its 21Hz @ -3db I also thought it might be a good idea cause of the MASSIVE magnet and its DEEP excursion (little over 45mm) and the fact that its almost 20w/1m sensitivity higher really makes me want to try it. Alas I will not go aganst the design I was just curious.

Armchair Pirate wrote: its 21Hz @ -3db...DEEP excursion (little over 45mm...its almost 20w/1m sensitivity higher

I don't know where you're getting that from, but it's not possible. Drivers can go very low, they can have very high excursion, and they can have very high sensitivity. But they can't have all three of those characteristics. In fact, if they have very high sensitivity then they cannot go very low and have very long excursion as well. And if these are used in the Mackie HRS 120 that's a home theater/hi-fi sub, not pro-sound, and it does not have 102dB/watt sensitivity. It might reach 102dB at full power.

Page 16 and 17 and this is the last time I will bring this up and THANK YOU FOR YOUR INPUT!!!
http://www.mackie.com/pdf/hrs120_om.pdf

Armchair Pirate wrote:Page 16 and 17 and this is the last time I will bring this up and THANK YOU FOR YOUR INPUT!!!
http://www.mackie.com/pdf/hrs120_om.pdf

There's no definitive engineering data there at all, just marketing piffel, including another magic amp that delivers more power than it consumes. Perhaps it employs Cold Fusion?

I've had my share of Mackie stuff over the years and have had good results with it. It's been a few years so I don't know what the new stuff is like. Apparently not as good.

Yeah, there's just not any T/S parameters here. Since you work at a repair shop do y'all have a woofer tester like this: http://www.parts-express.com/pe/showdet ... er=390-804 See if the shop owner will buy one then you can test it out. If you can get them cheap might be worth finding out.

Specs I'm reading in the PDF is maximum system spl of 117db a 1 meter which seems fairly reasonable. Weird- some of the specs seem okay but I don't understand how the system can be drawing 280 watts with a loud mix but be rated at 400 w/rms.

Rick Lee wrote:
Specs I'm reading in the PDF is maximum system spl of 117db a 1 meter which seems fairly reasonable.

It's a calculated figure, not measured, and assumes there is no thermal or mechanical power compression. That's simply not possible. But working backward from that figure at 400 watts the resulting 1m/1w sensitivity is 91dB/watt, and that is not reasonable with a 19Hz F3. 86dB is about the limit with the cone mass that a 19 Hz F3 and 45mm xmax results in. And why do I have the feeling that xmax is a peak to peak figure, not one way? For that matter they don't say it's xmax, so it very well may be xlim.
It all boils down to the fact that, manufacturer advertising copy notwithstanding, there are no magic drivers either.

Bill Fitzmaurice wrote:86dB is about the limit with the cone mass that a 19 Hz F3 and 45mm xmax results in. And why do I have the feeling that xmax is a peak to peak figure, not one way? For that matter they don't say it's xmax, so it very well may be xlim.

Even to a non-engineer like me 45mm xmax sounds beyond belief. So trying to follow the reasoning here is the 86dB the sensitivity rating or about max output at 19hz? It's been so long since I've followed sensitivity ratings for ported or passive radiator cabs I've kinda forgotten what a typical 1w/1m rating would be in the 20- 30hz range with a 12" driver.

Rick Lee wrote: So trying to follow the reasoning here is the 86dB the sensitivity rating or about max output at 19hz?

Sensitivity. Higher sensitivity requires less moving mass, and that results in higher F3.

Rick Lee wrote:
Specs I'm reading in the PDF is maximum system spl of 117db a 1 meter which seems fairly reasonable. Weird- some of the specs seem okay but I don't understand how the system can be drawing 280 watts with a loud mix but be rated at 400 w/rms.

Side note: if I understand this correctly, the TableTuba will do 115db/30hz (113db/40hz) at 100 watts free standing;127db/30hz (115db/40hz) at 100 watts in a corner. Interesting!

Armchair Pirate wrote:I don't know where you got the low/mid part as everything I can find says its low. I was also wrong about the 17Hz its 21Hz @ -3db I also thought it might be a good idea cause of the MASSIVE magnet and its DEEP excursion (little over 45mm) and the fact that its almost 20w/1m sensitivity higher really makes me want to try it. Alas I will not go aganst the design I was just curious.

Copied from the E-bay ad you posted:

One Mackie RCF 12 inch 8 ohm
Low Distortion , Low Frequency Transducer . Made in Italy.

New Old Stock, used in the exquisite 1500+ watt Fussion SWA 1800 powered tops.

This is an original low/mid 12" speaker from Mackie /RCF / EAW Fussion SWA 3000
active powered systems. The SWA amp in these puts out 1500 watts to four of these speakers.

Big , heavy , beefy and reliable ... it is rated to handle 300-400 watts of power.

I'm sorry that you don't like what we will prove to you. Take a "leap of faith" and build one design, to the exact specs of the plans, and compare for yourself. We all have, and the vast majority are happier for it.

I am going to build them with the Lab 12"s. I have heard 4 T60s and it was nothing short of EPIC!! Loads of breathtaking deep detailed bass. When I found out they were roughly the same power rating as the SWA1801 with what felt/sounded like 10x that. I was speechless. Now as for "I'm sorry that you don't like what we will prove to you." It has nothing to do with weather or not I like what you are saying. I don't see the point in asking questions then "not liking" the answer, I am asking BECAUSE you guys have the knowledge that you do. $2k is A-LOT of money to me and I simply was curious about using what I originally thought was going to be a better driver for the same cost (they are $300+ drivers to the public). I was told some very valid points by some very experienced people. I figured RCF had to be on the right path cause man in the 1232s the duel 12" puts out so much clean tight bass and that's in a main. I know the SA1232 and HRS120 use different woofers but both are RCF and the HRS120 12" weighs (what feels like) 1.5-2x what the 1232 12" does and the magnet is freaking HUGE!! I really cant wait to finish the subs. although now I am REALLY on the fence about the T60s or T48s. After spectrographing quite a few tracks with the exception of very few. Alot played out very similar to this one I found that while I do have content as low as 20Hz its at @-45db @ 30hz its -35 @ 40hz its-26 @ 50hz its -19 then from 60 to 80hz its-15 with less then 2db change. So the T-48s are looking more and more like what I should do. Either way As soon as all 4 are done I am selling the SA1232s to build DR250s possibly 280s.

Bill, because I cant find any REAL specs on this "Magic" driver. Can I send you or someone 1 to have you check it out? Cause if it does end up being awesome then I can easily just switch out the labs and save them for a rainy day or another builld^^

Thanks to everybody on this forum, it has been a very humbling experience to stumble across this library of REAL information from people that REALLY know what the hell they are talking about.

If you want to get the specs, order a woofer tester from PE. They look like nice speakers and it might be worth your while since you have access to them.