My SMT212 CP755TI / SN12B
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Category: Plans
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URL: https://forum.speakerplans.com/forum_posts.asp?TID=17944
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Topic: My SMT212 CP755TI / SN12B
Posted By: login4
Subject: My SMT212 CP755TI / SN12B
Date Posted: 01 July 2008 at 12:39pm
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Hi guys finally finished my SMT212's and im well happy with them, its realy worth spending the time and money getting it just right. i had a few problems finding the quality ply i was after (11 lam 15mm baltic birch) and getting the SN12Bs but other than that it went very well inddeed. this build was the first time i had used a propper table saw with an adjustable gate and it made it so easy, in fact when putting them together i didn't have to hand plain anything at all and the joints met perfect,  so a good table saw goes a long way i think.right time for some pics:         And the finished product:     ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Replies:
Posted By: Tiff
Date Posted: 01 July 2008 at 12:50pm
| very very nice |
Posted By: (SoundcreationaudiO)
Date Posted: 01 July 2008 at 12:55pm
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crackin build Elwyn mate, really nice finish. turbo blue aldcroft?
The cabs to be Bi-amped, or you wacking a crossover in them?
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Posted By: login4
Date Posted: 01 July 2008 at 1:13pm
cheers guys, ye its turbo blue aldcroft, as many coats as mentally passable  there bi-amped running the SN12B's 130- 1.7kz on Matrix STR1500 and Beyma CP755TI 1.7kz - 20kz on chameleon 1100s and see how that sounds when doing some tests the other day i did an A / B comparison to one loaded with Eminence Beta's and the difference was incredible the p.audio's just blew them out the water and kicked like a mule, Good plans these, ill report more after a festival that im doing a stage at this weekend coming. p.s. cheers Mark James for getting the drivers to me so quick... ------------- CELTIC SUBSONIC SOUND SYSTEMS |
(SoundcreationaudiO) wrote:Posted By: Mark James
Date Posted: 01 July 2008 at 1:33pm
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awesome glad your happy with them!!! Nice build too, looking good! ------------- me so horny me love you long throw horn loaded for her pleasure |
Posted By: Tekasis
Date Posted: 01 July 2008 at 1:38pm
Info sounds good - They look impressive btw!
------------- **Heavy Weight-Line** A home without books is like a body with no soul. |
Posted By: biotec
Date Posted: 01 July 2008 at 1:42pm
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I don;t really understand why people with clearly excellent woodworking skills would build such a basic cab.
As far as I can tell cabs like these are great if you are short of time or have basic woodworking knowledge but if these don't apply a proper exponential or tractrix horn would be better. ------------- me so horny, me love you long throw. |
Posted By: Tiff
Date Posted: 01 July 2008 at 1:50pm
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what was the total price of your drivers per cab? u had a proper listen to them yet? |
Posted By: login4
Date Posted: 01 July 2008 at 3:11pm
i can see your point but for me i wanted medium throw because i do both indoor and outdoor gigs and iv found with full horn loading it can be a bit to directional and unless your using lots of mid tops you cant get the coverage. also the way i look at it iv got the dirvers needed now so in the future i can build something else if needed, the other thing with full horns is they mostly only cover smaller band widths. TIFF, I reckon the total cost was around £1000 iv had a good play with them in my workshop and they sound very good so far, ill let all know after this weekend coming (live bands all weekend at a festival, 60' x 60' square) ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: tomschute
Date Posted: 01 July 2008 at 3:31pm
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I have to say i thought these were a basic cab but once you hear them in action you would be very impressed. They look sooo good too - think it's the turbo blue. Great job EL, we'll give em a good blast this week... ------------- Out to lunch... stableaudio@hotmail.co.uk www.stableaudio.co.uk Speaker Building Services |
Posted By: cravings
Date Posted: 01 July 2008 at 3:42pm
| lovely build. they look great. |
Posted By: Tiff
Date Posted: 01 July 2008 at 5:57pm
| £1000 per cab????? surely u mean the pair? |
Posted By: vwbidder
Date Posted: 01 July 2008 at 9:57pm
Those are sweet looking cabs I assume their performance is somewhere between the X12 and the MT122? Can 2 per side be used to get good coverage and decent throw. How low will they play?
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Posted By: login4
Date Posted: 08 July 2008 at 10:04pm
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TIFF, ye about 1000 the pair. vwbidder two a side would cover a nice wide area, good for clubs etc, day time pic:   the photos were taken at a festival called the workhouse festival (courtyard stage) all in all they sounded very sweet, really kicky mid and crisp top end, the only thing i picked up on was there was a note that seemed to resonate sometimes it might of just been the venue or me just being picky but im going to run them through the computer at some point and see if there's any nasty peaks or dips in the response p.s. wow those Beyma's sound nice ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: wafflesomd
Date Posted: 18 August 2008 at 6:15am
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How many sheets did it take for two? |
Posted By: tomschute
Date Posted: 18 August 2008 at 10:42pm
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one per cab covered it if I remember rightly.
------------- Out to lunch... stableaudio@hotmail.co.uk www.stableaudio.co.uk Speaker Building Services |
Posted By: login4
Date Posted: 19 August 2008 at 12:02am
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ye toms right, two sheets with a bit to spare ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: Zollax
Date Posted: 19 August 2008 at 11:53am
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Nice work there I realy wanna know how they sound compare to the MT122  And how low and high the 12" speakers can play.
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Posted By: login4
Date Posted: 19 August 2008 at 7:49pm
cheers man, well iv never compared them directly to a MT but id imagine there not as efficient as an MT but they still project the sound nicely, and the dispersion seems fairly wide on them i run mine from 130hz - 1.7khz, they would probably go a little higher and lower tho without too many problems.... ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: Zollax
Date Posted: 19 August 2008 at 8:54pm
Okeey  You said earlyer that the Eminence beta-12 didn't preform so well in this cab. Do you think the Eminence Delta-12 would do a better jobb? |
Posted By: wafflesomd
Date Posted: 19 August 2008 at 9:09pm
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Speaking of, for anyone in the states. http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=299-500 |
Posted By: Flano
Date Posted: 19 August 2008 at 9:30pm
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Nice job indeed.... Whats the weight of these cabs come in at?Are they your fame subs in the pic? |
Posted By: login4
Date Posted: 20 August 2008 at 10:41pm
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ye i think the delta 12 would be much better, Flano ye there the fame subs i got from germany, there pretty good to be fair, realy quite kicky, and go fairly low, i hi pass at 35hz which seems to be fine, they might be for sale soon as im thinking of down sizing a bit, and the pa bug is calling, as for weight of the tops i can lift one by myself and move it around but need two to stack one, also there quite top heavy because of the Beyma comp driver ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: wafflesomd
Date Posted: 21 August 2008 at 1:25am
| I'll be building a pair here soon. Probably won't be nearly as nice as yours, but I'll try :) |
Posted By: roborg
Date Posted: 21 August 2008 at 2:06am
nice cabs, i used the same drivers in my mid-tops. Are u gonna use your cabs in or around London soon, be nice to hear them? Those sn12b's are seriousaly nice drivers, even nicer with a phase-bung  . I made mine out of 12mm to keep weight down, i used good old black aldrcroft, will add a couple-a more coats when i get back to them in a couple of weeks.
I reckonned i spent 800quid a pair, so a very cheap cab for their performance.:
   cheers,
Rob. ------------- What I cannot create, I do not understand |
Posted By: roborg
Date Posted: 21 August 2008 at 2:09am
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hehe that cab got a bit mangled ------------- What I cannot create, I do not understand |
Posted By: login4
Date Posted: 21 August 2008 at 11:01am
 i remember the build pics of those cabs, thats some great wood work mate, did you ever do an A/B comparison one with phase plugs one with out? ye i really like the SN12B's, very solid sounding and a bit of a steal if you ask me wafflesomd, what Compression drivers will you be using? ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: login4
Date Posted: 02 September 2008 at 12:00am
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hi guys, if anyone is interested ill be taking out the SMT's this weekend to: Grass roots festival (muddy promotions) http://www.thegrassrootsfestival.co.uk/ - http://www.thegrassrootsfestival.co.uk/ the festival is held near peterborough and ill be on the Circuit Tree stage, come have a listen it would be great to meet some peeps off here... ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: jonny4288
Date Posted: 04 September 2008 at 9:36pm
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just noticed you had them at workhouse festival, only 40 mins down the road from me.
you doing anything else local soon, im stuck on what im going to use for midtops for the rig im putting together, would like to listen to a few differnt tops to get an idea of what will compliment the rig best.
x1 letterbox with 4 hd15's and 1 or 2 midtops per stack. just building the 1 stack for now though.
will mainly be used outdoors in ruthin/denbigh area (clocaenog forest)
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Posted By: login4
Date Posted: 18 September 2008 at 12:12am
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hi jonny, iv been to some good woodland events up there im not sure when the next time ill be up that way but ill be sure to drop u a pm if i do. in your system id say something fairly small like a porn horn type cab should do it, i haven't tried my SMT212's above a kick section yet, i dont feal they need it but ill look forward to the results. last outing the other week:  (fish eye)  ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: wafflesomd
Date Posted: 03 November 2008 at 3:00am
I havn't decided. I'm currently searching for drivers on a budget for these cabinets. I should have built some X12's. It's hard to find a driver for cheap that will work well in these. |
Posted By: login4
Date Posted: 03 November 2008 at 7:14pm
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perhaps a p.audio BM D740, 1.5" exit
------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: djstefanos
Date Posted: 03 November 2008 at 8:20pm
| do you have issues with balancing when lifting up from the flush handles? |
Posted By: Deadbeat
Date Posted: 03 November 2008 at 8:25pm
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wafflesomd, try selenium as well for comps.
------------- Away on extended leave. |
Posted By: login4
Date Posted: 03 November 2008 at 8:38pm
they are a little top heavy with that monster comp driver in but its not too much of a problem as i put another handle on the back of them too this also helps for going up stairs as the one going up first can grab the handle with one hand. i would advise putting the side handles a little higher than i did. ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 4:11am
| Do you think that P.audio will keep up with two Emeinence Delta's? |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 6:45am
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So I'm actually trying to figure out what type of driver works well in this cabinet. I'm trying to actually understand QTS and how it plays a role in this. I tried finding drivers that match the specs of the P.Audio you used. It's kind of hard to find a qts of .16.
Can't seem to find any drivers with a similar BL either. Not to many with the same VAS either. |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 7:38am
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Ok. Turns out my issue was that I was running the 12's way to high. I had them crossed at 2.5khrtz to meet my current tweeter. Plan is to buy a midrange, and run a 3-way with this cabinet.
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Posted By: LunchieTey
Date Posted: 05 November 2008 at 8:13am
Don't forget the whopping 10db spike in response on the deltas between 1 and 2k translating into harsh sounding mids  Many eminence drivers have the same problem so don't feel bad!www.eminence.com/pdf/delta-12a.pdf, see that huge peak from 1.8 up? That will rip ears too unless you eq you will also need a good highpass, 2.4mm x-max.I've been looking thoroughly at these plans and might just build a pair(15mm ply is literally piled up where i work and I mean 2000 sheets or more! and is free!) I have a pair of bmd-750's ph-4528 horns, and 4 sn-12mb's. I want to ask a maybe silly question... Is the open void behind the compresison driver used by the 12's or is it only the airspace behind the baffle itself? edit, have looked at other post with build pics, can see horn area is closed off ------------- Speaker addict |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 7:16pm
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The tweeters chamber is seperate from the woofer. It's seperated by piece F. Which is too long. It should not be 388mm. You'll have to figure out how long it needs to be. It depends on the thickness of wood you used. So my plan is to run the 12's from 80-500, then a mid range from 500-3.5k, then the compression gets the rest. Has anyone modeled the 12" section in hornresp?
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Posted By: djtecthreat
Date Posted: 05 November 2008 at 9:08pm
As far as I know; No. I believe hornresp wont do mid range freq. Plus the SMT isn't really a horn, it's a wave-guided reflex. -Tec |
Posted By: Deadbeat
Date Posted: 05 November 2008 at 9:35pm
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Hornresp has it's limits - but you need to know them accurately (do a search on power response). Lots model mid on hornresp... THs SMT212 is a reflex design - the waveguide is there to lend a bit of directivity and wavefront control. It's old school design which I've touched upon in the past - there's a thread that mentions the altec VOTT which has some info in for anybody wanting to know how to design a mid 'flare' as opposed to a horn. ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 10:24pm
| so I should be treating this like a reflex? |
Posted By: Deadbeat
Date Posted: 05 November 2008 at 10:53pm
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Treat it as a direct radiator if that keeps it simple. Hornresp can do the low end response - how high the double twelve section goes will be determined by individual driver response which you can't model. Check manufacturer's driver's plots - it is best to cross below driver breakups (easily spotted on the FR plots) and below when the 12" starts beaming (see polar plots - otherwise this is around 1k2 for most 12"). ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 05 November 2008 at 11:00pm
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I should be fine running the 12's from 80-500 then. The drivers I used peak up at around 100, then dip down about 10db at 400hrtz for some reason. They'll be replaced soon. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 1:46am
| Is there a reason why the rear chamber was made so small for this cabinet? |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 4:43am
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Did you ever get around to measuring them and checking for peaks and dips.
I may just be ditching these cabinets and going for something else. It seems like there will always some annoying resonances just based on the cabinets design.
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Posted By: LunchieTey
Date Posted: 06 November 2008 at 8:10am
It may just be your choice of speaker, you said you tried it with drivers that have a qts of 1.3 and the deltas(if you have them now) have a big response peak and also don't like small boxes! Maybe if you decide to bin them, open up the extra space behind the compression driver?Or put in the ports(hole saw ) might lower the resonant frequency of the cab as you didn't port yours(high q alignment with the deltas will give you a big resonance at fb) Also try stuffing the rear chamber if you stay sealed.------------- Speaker addict |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 8:29am
I do plan on porting them. I was talking to a friend of mine, and he stated that buy design, the cabinet will resonate at 400-500hrtz. I guess I'm going to hold out until I get some proper drivers. I'd like to see some measurements with some Delta's, or other drivers. I really can't stand resonance at all. I havn't purchased any new drivers yet. Seems like the only driver that has been proven to work well is the p.audio sn12b. That driver is far to expensive. I can't find another driver with even close specs. It seems like the x12 might be a better solution for me. I'm not looking to spend huge amounts of money on drivers.
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Posted By: Tekasis
Date Posted: 06 November 2008 at 10:01am
You tried looking at the Celestion Truvox series ?
------------- **Heavy Weight-Line** A home without books is like a body with no soul. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 10:22am
| I'm not sure how well those would work. The specs are close the Emeinence beta and delta. |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 8:37pm
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wafflesomd - you also need to look at polars, FR graphs, etc to determine breakups and beaming and is essential in selecting xover point. This gives you a clearer picture. ' I was talking to a friend of mine, and he stated that buy design, the cabinet will resonate at 400-500hrtz. I guess I'm going to hold out until I get some proper drivers. I'd like to see some measurements with some Delta's, or other drivers. I really can't stand resonance at all. ' What was he talking about? Any reasoning you could enlighten us with?
------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 8:43pm
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He based this on the fact that the bottom, and piece F are parrellel and don't expand. I probably said that wrong.
Do emeinence have polar measurements?
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Posted By: Deadbeat
Date Posted: 06 November 2008 at 8:49pm
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Haha. In that case all our speakers are flawed. Anyway. Tell your friend that he is right in noticing standing waves in a cabinet caused by parallel sides. The distance from Piece F to the bottom is 680mm. This is the wavelength of 500hz - he's done the math right. Unfortunately, the driver's chassis and cone are in the way of nary a standing wave . Besides - any standing waves formed would be chased away if you stuffed and lined the boxes properly when finished.------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 8:51pm
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Neato. So how would I go about stuffing and lining these?
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Posted By: Deadbeat
Date Posted: 06 November 2008 at 8:54pm
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An average 12" begins to start being directive (beaming) at 1k2. Most manufacturers will give you polar plots at several frequencies. I don't think eminence do. If you wanted to be absolutely sure any standing waves were absorbed - I'd staple a thin layer of closed cell to the top and bottom of the chamber. ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 8:58pm
| The rear chamber, the waveguided section, both? |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 8:59pm
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Just the rear chamber where your friend is mortally afraid of resonance. Top and bottom. Closed cell. Thin layer. Staples. ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 9:04pm
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Thanks for the help. Now it just comes down to driver selection. Using a 3 way design would be the most cost effective thing to do. Most 2" are very, very expensive, and the horns are as well.
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Posted By: Deadbeat
Date Posted: 06 November 2008 at 9:12pm
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What's your budget for the whole lot? ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 9:17pm
| Does $500 sound reasonable? |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 9:18pm
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Is that a single or the pair? ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 9:26pm
| For the pair. |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 9:33pm
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4x Selenium 12PW3-SLF from partsexpress is $188.80 4x Selenium 12PW5-SLF from partsexpress is $297.60 I like the DR output from light cone drivers. Think JBL E120.
------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 9:39pm
| I'll assume those drivers will perform well in the cabinet? |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 9:42pm
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I've used the PW3 in a reflex and it had quite the HF response. You might want to check on winisd of course. ------------- Away on extended leave. |
Posted By: Paulo Duto
Date Posted: 06 November 2008 at 9:43pm
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Hi
Made a pair of SMTs using a 12" Eros, Qt 0,35, Vas 65, Fs 50, Re 5,9, BL 16,90 Pe 350W, x-max 3,MM, Spl 95,2, and a 2" driver in the hf horn as in picture:
Crossed them passively around 1,6kHz and around 100Hz active:
Used the pair with four modified 1850.
All I can say all me and audience were very well impressed with that little PA.
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 A closer view of the grills before attaching the foam:
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 Passive Crossover:
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 I recommend select a good woofer that work well BR up past 2Khz...
Regards, ------------- Paulo Duto |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 9:48pm
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The PW3 would work very well for my budget. It looks like it's good up to 2k as well. Polar's look good. Now for the compression tweeter. I assume I'll need something that will go down to 1.2.
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Posted By: Deadbeat
Date Posted: 06 November 2008 at 10:07pm
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You'll be wanting a horn to support that frequency as well. Take a look at 18sound's and Faital Pro's offerings on usspeaker.com Use the search function if you want to know opinions on comps. ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 10:17pm
| I don't think I'll be able to stick within the budget on the HF drivers and horns. Oh well. |
Posted By: Paulo Duto
Date Posted: 06 November 2008 at 10:18pm
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Hi
May I disagree?
Let's compare the curves of the woofers you refered:
Firstly the 12PW5 you can see the first peak around 350Hz and than the valley between 400 and 600Hz (-6dBs);
This driver is an upgrade from the 12PW3 (changed the aluminium dome for a paper one)
Now look at the 12PW3 plot,; this is an upgrade from the 12PW2, which present an analog cancellation mentioned of the 12PW5; they corrected (minimized) this but introduced the two big peaks when the dome sings (+6dBs between 1 and 2KHz and than a new valley at 2Khz returning to 0dB position, and than a Everest of +10dBs between 2 and 5 KHz).
This 12 PW3 was or is used for guitar boxes (how reproduce 600Hz?);
For guitar box may I suggest the 15PW3; made some boxes with succes;
Returning to SMT212 how about experiment the WPU 1209?
 12PW5 qt 0,31 12PW3 qt 0,61 WPU1209 qt 0,32Regards, ------------- Paulo Duto |
Posted By: Deadbeat
Date Posted: 06 November 2008 at 10:23pm
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I presented wafflesomd with the two lowest priced drivers. You can't have a free lunch obviously as presented. ------------- Away on extended leave. |
Posted By: Paulo Duto
Date Posted: 06 November 2008 at 10:34pm
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OK Deadbeat Follow beside my comments refer to compression of 4,3dBs at 0 dB and qt 0,61.Experience with that driver in Selenium horns similar to MT102 always indicate failure due to the absence in play low mids, when people try to eq it;
Play some sims with it BR and you will have a preview.
Regards,
------------- Paulo Duto |
Posted By: wafflesomd
Date Posted: 06 November 2008 at 10:52pm
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I don't think they make the wpu 1209 anymore.
This is kinda why I would rather build the x12. Four really. I can make four, good sounding x12's for the price of one good sounding SMT212.
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Posted By: Paulo Duto
Date Posted: 06 November 2008 at 11:57pm
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Hi At Seleniuns site they are apparently in production;
Everyone knows what he can spent and what hope with the investment. Would only advice you before waste money with 12PW3...
Only referred 1209 as Deadbeat was indicating Selenium drivers and it is a good one; Here in Brazil these WPU1209 are not cheap (R$380,00 =>> before crash rate was R$1,70 = US$1,00 now R$2,10 = US$1,00;
Regards,
------------- Paulo Duto |
Posted By: wafflesomd
Date Posted: 07 November 2008 at 1:14am
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I'm just going to build four x12's and four g subs.
I think this cabinet is bad by design. There will always be standing waves in the front section of the cabinet. Placing padding in the rear of the cabinet will help, but you would still need to absorb waves in the front. That's going to significantly reduce SPL.
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Posted By: LunchieTey
Date Posted: 07 November 2008 at 9:14am
Only they way you are doing it, it's fine if built how it is specified. When I get around to it, I will be building a pair and will post results, may be a few weeks yet though These will be with p-audio sn12mb's(slightly different specs but oh well-that's what eq is for)------------- Speaker addict |
Posted By: Paulo Duto
Date Posted: 07 November 2008 at 12:59pm
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Hi
That's your choice.
Remember diffraction loss that occurs when you lift the boxes from the ground plane..
Have you added all the braces of the project?
If you nit made it BR it would not play low mids at all
Take a look at Pi forum at the for the driver of Pi project:
http://www.pispeakers.com/Components/Delta12LF.pdf - http://www.pispeakers.com/Components/Delta12LF.pdf
Also value take a look at BF forum to the speaker indicated for the Omnitop12; following it plans you will find out a way to extend response of the 12", without adding phase plugs, and so turning the HF drivers life easer.
Good luck!
Regards, ------------- Paulo Duto |
Posted By: Deadbeat
Date Posted: 07 November 2008 at 1:07pm
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Standing waves aren't as much of a big deal in a design like this. The small rear chamber means that the drivers will be in the way of any standing waves. The front isn't as affected as much either - and if you lay down the foam - all you are doing is padding down the top end of the driver response which won't matter since you're crossing to the comp. One of my favourite quotes is actually from Siegfried Linkwitz, on standing waves - I can't find it atm so never mind.. 2 X12s and 4 GSUBs is a good plan though ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 07 November 2008 at 5:52pm
| Yes, x12's and gsubs will be a lot easier for me to control and use. They should put out a great deal of sound as well. |
Posted By: djtecthreat
Date Posted: 09 November 2008 at 7:16pm
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For the record- Delta-12A under Selenium D210ti sound incredibly good for $205 a cab. I'm impressed and happy and cant wait to finish all 4 of my SMT's. |
Posted By: Deadbeat
Date Posted: 29 November 2008 at 8:16pm
Damn! I hate it when I post at odd hours. I am wrong here, and so is wafflesomd's friend. Box resonances occur at half wavelengths at parallel walls. They cause notches in the response. 344/0.68/2 = around 250hz. There would be additional resonances at 750hz, 1250hz, etc. However, there is a major flaw in this....er....it hardly has an affect in this horn in real life conditions. The back chamber is full with speaker cone and magnet, so one won't have resonance there. The front waveguide is too short to really create any ridiculous resonances imo. If you calculate resonances obsessively, nearly all designs are crappy .Resonances from ports, boxes, etc, become apparent in FR graphs. You should also be able to hear them If they ain't there, they ain't! ------------- Away on extended leave. |
Posted By: WmAx
Date Posted: 30 November 2008 at 5:59am
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I am wafflesomd's friend that was mentioned previously in this thread. The main resonances of this cabinet will be in relation to the front section, with the substantial near-parallel sides on both sides of the midbass drivers. This is going to cause substantial resonances and cancellations in the lower to upper mid-rand band if left bare. Of course, I realize this is no hi-fi sound reproduction system, but instead, simply a P.A., but none the less, is an issue that will be addressed if maximum fidelity is so desired. BTW, standard dampening foams are near useless in many cases. The standard 1" acoustic foam has virtually no action under 1200Hz, and the staneard 2" acoustic foam has little action under about 600Hz. If it is a premium grade foam like Auralex(and most are not near this quality), then those figures are approximately halved(600Hz, 300Hz). A better and cheaper material is 6-8# mineral wool board. In 2" thick, it has a very high absroption co-efficient at 250Hz, for example, before it starts to reduce in effectiveness. Cabinet panel resonance also reduces fidelity substantially, but again, that is probably not that big of a deal in P.A. systems. I have actually never noticed any P.A. system with low resonance cabinet panels. Heck, most so-called hi-fi high dollar speakers have relatively high resonance panels. It's not really feasible in most cases to prevent this problem, especially in P.A., due to the usual side effect of very heavy cabinets that result in substantially reducing resonance with standard methods that are highly effective. There are relatively low weight solutions, but this would likely result in very complex cabinet construction which translates to very high cost or very high labor(in the case of DIY). -Chris |
Posted By: Deadbeat
Date Posted: 30 November 2008 at 11:55am
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Hi, Measure the speaker and see whether this is true in practice. It all comes out in the graphs. Standard acoustic foam (30ppi open cell) is useless in this place. What I am however referring to is closed cell foam which does help. I've measured it affecting FR. The mentioned wool will help. Sorry for any confusion. The 30ppi foam, is good, as I have maintained, for absorbing any higher order mode distortion. But that's a different topic. The main point was that such resonances will happen in half wavelength, not full as specified. In practice, the extent will be revealed by measurement, and then you apply fixes. We all strive for high fidelity. Resonance in panels, eh? I've got a link to measurements of energy transference in loudspeaker cabinets of different materials. Somewhere... Here's a short bit I wrote a bit earlier on material. 'Resources: diyaudio.com and some personal experimentation in the past, Ron Clake for my sentence or two on damping. Well, the object of a speaker cabinet material is to not affect the sound of the cabinet. Sound travels faster in solids. The issue with panel resonances and all of the other talk around that factor is to do with energy storage, and release. You want to control this so it achieves the objective, as it is impossible to stop any resonances happening. What you do is stick the panel resonance up or down relative to the cabinet passband. Option one- using MDF, HDF, hewn Now for more detail: MDF breathes. You car audio guys should know this, it breathes, and you have to paint both sides to stop it. Energy loss in laminated enclosures. Ron Clarke: One of the good reasons for the application of ply in enclosure applications is the fact is thats its a laminated medium. Any energy has to encounter several interfaces, every time an energy encounters an interface of different values it gives up greater energy than a monochromatic singular medium due to the loss at an interface. Simply put, the more interfaces an energy has to encounter the greater the loss of energy, thus the more damping. My final point. Stiffness. Stiffness can be checked by Young's Modulus. MDF and chipboard aren't stiff at all. Fir ply is stiff. BB is even stiffer. You can google for average Young's Modulus values of whatever material.' Siegfried linkwitz once mentioned that his speakers were boxy because any resonances created would be easier to notch out if they appeared, than curvy ones. That's not an exact quote. Nice to have you on board. Omar ------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 30 November 2008 at 12:35pm
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I probably won't be testing these out anytime soon. I need to invest in some fane 15" reflex 2 ways. Those will work much better for me at the moment. It would cost quite a bit to get drivers that will work well in these cabinets. |
Posted By: Deadbeat
Date Posted: 30 November 2008 at 12:39pm
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Sorry mate, we've gone a bit off topic
------------- Away on extended leave. |
Posted By: wafflesomd
Date Posted: 30 November 2008 at 1:00pm
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Not at all. I enjoy talking about theory and doing some research. Oh wait, this isnt my thread lol. |
Posted By: Deadbeat
Date Posted: 30 November 2008 at 1:32pm
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We hijacked a hijack
------------- Away on extended leave. |
Posted By: login4
Date Posted: 30 November 2008 at 10:37pm
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i tell ya what lads ill try and get some sweeps etc done on mine asap and then post the results up on here,
------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: shello79
Date Posted: 08 June 2013 at 3:00am
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would these work mccauley M1220 Specs: Nominal Diameter 12" / 305 mm Rated Impedance 8 ohms Power Capacity 600 Watts Program Sensitivity 101 dB Frequency Range 75 Hz - 4000 Hz (+/- 3dB) Highest X-Over Fq. 3500 Hz Recommended Enclosure Volume .5 -1.5 Cubic Feet / 14 - 42 L Effective Piston Diameter 10.23" / 260 mm Voice Coil Material Copper Clad Aluminium Voice Coil Winding Depth 0.45" / 11.4 mm Voice Coil Diameter 4" / 100 mm Magnetic Coil Gap 0.3" / 7.62 mm Magnetic Assembly Weight 19 lbs. / 8.6 kg Flux Density 13,800 Gauss Bl Factor 19.4T *m(8) Moving Mass .045 Kg Theile-Small Parameters Fs Free Air Resonance 52 Hz Re D.C. Coil Resistance 5.6 (8) Qts Total Quality Factor 0.215 Qms Mechanical Losses 7.25 Qes Electrical Losses 0.222 Vas Equivalent Volume of Air 82 L Sd Effective Piston Area .053 square meters Xmax Excursion - Max Bl 3 mm Vd Sd x Xmax 159 cubic cm Mms Effective Moving Mass .045 Kg Le Inductance of Voice Coil 1 mH %eff Mid Band Efficiency 5.1% Pe Max Power Rating 300 watts RMS Sine Wave i have six of these and i would like to build the smt to go on top a few mini scoops any help would be greatly appreciated thank you ------------- Work hard play even harder |
Posted By: nkdk
Date Posted: 17 August 2014 at 5:19pm
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Hi very nice build I have build a pair to , with a pair kappa 12 a from eminence and a Rcf 2" driver. Did you use damping behind the too 12" drivers ? nkdk |
Posted By: login4
Date Posted: 14 September 2014 at 6:55pm
hi, yes i always dampen my speakers, especially mid's ------------- CELTIC SUBSONIC SOUND SYSTEMS |
Posted By: Fracture_clinic
Date Posted: 11 March 2019 at 1:33pm
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Sorry to hijack a hijacked hijack.. does anyone know the dispersion of the 12 inch section (single)? TIA Build thread coming soon. |
Posted By: sushi
Date Posted: 29 March 2019 at 11:21am
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Hi there! I'm about to build a pair of smt's: i'm going for the single 12" version, after i modified the plans and verified all measurements are correct. I've read someone loaded the smt-212 with Eminemce kappa12a.. any feedback? how did it sound? I already have a pair kappa12a and i'll surely give a try 'cause i like how they sound.. but i know they usually work well in big boxes, smt's on the contrary have a really small chamber!  I'm going to try to load the speakers i already have. you know.. trying doesn't cost anything (but time). Anyway, I'm a little anxious because if they won't sound well i'll have to spend a lot of money for a pair of 12": 18sound 12nd710 is far too expensive, B&C 12pe32 is much more affordable but i'm not sure it's a good choiche (Vas is similar to the kappa12a, i'm afraid it's not good for a little chamber as well). There's no way i can get a pair of p audio sn12b (way too expensive, plus having them shipped to italy would cost me a lot). I'll give my feedback when i finish the job. In the meantime, if anyone had tryied the smt with the kappa12a, please let me know. Cheers! |
Posted By: Fracture_clinic
Date Posted: 29 March 2019 at 11:27am
| Can you access any RCF drivers? or Beyma? The B&C isn't a bad choice from what I've read. I'm going with the RCF LF12G301, the MB12G301 would be another similar choice if you're always going to be using kick bins (or BR that you can cross straight into). |
Posted By: sushi
Date Posted: 29 March 2019 at 1:36pm
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hi! thank you for your answer! yes i can easily access RCF drivers.. honestly, i think the LF12G301 it's just too low freq, must be kickass for basses, but doesn't reach the 2.5 or 3khz where i need to crossover them.. On the contrary the MB12G301 can do the job perfectly: 72 liters is the lowest Vas i've found so far, probably works well in SMT's chamber! ...and the price is good for a 400w/98db RCF driver! thank you for your advice! i think i'm going to try with the MB12G301, i'll also test the difference in performance between them and the Kappa12A. oh right.. one point i was missing.. I'm going to use the SMT's on top of a kick section (2 HD15 loaded with Eminence Kappa15LFA) and a sub section (2 ESW1018 loaded with RCF L18S801) ..planning to double-up the rig, somewhen, and build other 2 kicks and 2 subs (or maybe sell the ESW1018 and build 4 WSX, in my porn dreams ) |
Posted By: Fracture_clinic
Date Posted: 29 March 2019 at 1:41pm
Yeah you're right to meet a comp well the LF doesn't really have the required specifications, I should have added that I'm going to be running an 8 inch mid driver between my 12 and 1. If you're using HD's then absolutely use the MB not the LF! I must admit WSX have impressed me in the past.. I think I just don't like their bracing though haha! |
Posted By: sushi
Date Posted: 29 March 2019 at 6:29pm
yeah, those round bracing are not nice, moreover are useless if you don't mount a protecting grille. i'll probably modify them, i'd rather have invader-looking braces on WSX's.. not going to look like the original martin audio, but i'm always honest about having a selfbuild rig (and proud as well) cheers mate!
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