What would you do with 4 ACI SV12's?

[sub_crazy]

My sister a brother in-law just bought a new house which has a great room for a dedicated home theater. Since I have already made a subwoofer for my brother and friend my brother in law wants me to make up some for him.

I was thinking about using (4) ACI SV12 12" subs since they are on sale and are easy to drive. I may be able to do even more than 4 as the room is big and the price is right.

Here are the TSP's but they are already pre-loaded in WinISD so that is cool.

Impedance: 4 ohm
RMS Power: 350 watts (system power 500 watts)
Sensitivity: 90dB
Fs: 17.5Hz
BL: 8.9 Tm
Qms: 8.35
Qes: 0.41
Qts: 0.395
Vas: 250 liters
Cms: 1041.67
Mms: 99 grams
X-max: 12.87mm peak
VC Ø: 2" (51mm)
VC Height: 31.75mm
Air Gap Height: 9.652mm
VC Inductance: 1.45mH
VCR: 2.97 ohm

Frame diameter: 12-3/8"
Cut out hole diameter: 11-1/8"
Flange thickness: 3/8"
Depth: 5-13/16"
Overall height: 6-3/16"

And here is a link to what ACI recommends: http://www.madisound.com/catalog/PDF/SV12Specs.pdf

I already know that WinISD recommends a 8.3 cu ft enclosure for a .7 Q but that is not going to happen. They have enough money to afford a good eq to lower the response and a beefy enough amp to power all.

I do not want to make huge enclosures as they want to keep the install simple so I was thinking about 4 to 5 cu ft sealed enclosures with 2 drivers each. I will probably have them downward firing so I can skip making a grill. My brothers sub is only 1.8 cu ft and it really fills up his room so they are expecting something small.

I did see the thread using 2 ACI SV12's in a large ported enclosure but that is WAY too big. I would rather use multiple sealed enclosures which I can probably do up to (8) SV12's if need be.

Any suggestions would be greatly appreciated.

[Mike P.]

4 subs can be wired for a 4 ohm load. What amp will be powering the subs?

[sub_crazy]

Since my sister and brother in law are not one to blast the volume I was thinking about using a single Dayton HPSA1000 plate amp as I want to use something that has auto on/off or the ED LT/1300. For them simplicity is the key so I want to make sure they can control the whole system from a single remote like the Harmony 890 through RF. I am aware that the Dayton does not put out it's stated power per ChasW's measurements but I have used it in the past and it performs well. I am not sure if anyone has tested the LT/1300?

I normally use pro-amps and my friend and brother both get by but they are gear heads too so turning on an amp is not that big of a deal there.

Any other amps with auto on/off that would work in this application? I was thinking anywhere from 200 to 400 watts per driver would be more than sufficient but of course the more the better.

[Mike P.]

There's no need for that much power. 4 subs wired in 4 ohms can be driven by a Bash 500 watt plate amp. With the HPF set at 13.9 hz, the subs are driven to Xmax with 500 watts. Boosting the low end is not an option as the subs are already at Xmax at 20 hz.

[sub_crazy]

I was just going off the assumption that since ACI uses a 250 watt amp for there Titan XL that was what is needed for each driver.

Your right on the power requirement, I just never got around to checking that off of my assumption.

The good thing is I already have a O-Audio plate amp that I never got around to using for another project so I can use it here.

Thanks

[Mike P.]

The O-Audio will work nicely with the HPF set at 20 hz.

[sub_crazy]

Hey Mike and anyone else who may be interested.

I had a 5.2 cu ft sealed enclosure that I used to test some other drivers and decided to retrofit it to house a pair of SV12's. I just wanted to see what these drivers were capable of before starting a project for my brother in-law and to also try out my new Dewalt 621 router with integrated dust extraction

Both subs are forward firing but if this works out I was going to make it a downward firing sub so I could skip a grill and the drivers would be protected from the kids.

I already had my QSC PLX2502 in the rack so I decided to try the subs connected to a single channel which is rated at 425 watts into 8 ohms. The drivers are wired in series and I measured 6.7 ohms at the binding posts. I used a SMS-1 to boost the low end and tame some peaks. I actually got a really good flat response to 20hz, one of the smoothest responses in my room.

The subs is sitting on top of my Mal-X as that is the best spot in the room for a single subs and I was too lazy to move the Mal-X.

I started with music and was impressed at what I was hearing with no break-in at all. I then went straight to LF or DH Blu-ray and put on semi vs jet fighter and was again impressed. Next was a few scenes from Shoot em up and the SV12's filled up the room.
I looked carefully at the drivers and they did not distort or make any mechanical noises that would indicate any stress. The bass was more room filling than hard hitting like the Mal-X or the various TC Sound drivers I have but I liked it. I honestly was expecting some distortion with the amount of boost I applied and the power I was putting into it but the drivers sounded like they were loafing along.

I will have to try it out downfiring as right now it is sitting 2 feet off the ground and the closest wall is about 3 feet away so it is not getting any help from boundaries so I would expect it to hit even harder when coupled to the floor. I still need to make feet to lift it off the ground though.

I did e-mail Mike over at ACI to ask about third-order sealed enclosures using capacitors that they mention in there PDF of the SV12. This is said to lower the response in a sealed enclosure. I have not heard back yet but he usually gets back within a few days.

For the price these drivers are a steal. I was thinking about making 2 subs with dual SV12's each for my brother in-law but from how this fills up my big room 1 may be enough. That will leave me with some for myself

These are still available from here for a closeout price http://www.madisound.com/catalog/pro...oducts_id=8639

They also have the SV10 but I don't know how they perform.

[Mike P.]

Glad to hear it worked out as well as it did. For $75 a piece it's a great deal.

[GPM]

sub_crazy wrote:

Both subs are forward firing but if this works out I was going to make it a downward firing sub so I could skip a grill and the drivers would be protected from the kids.

Greets!

FWIW, a 5% max offset due to sag is generally accepted, but this driver will sag >8.75% based on the specs you posted. This equates to 1+ mm of its Xmax being effectively lost, so Caveat Emptor.

GM

[sub_crazy]

Thanks for the tip on sagging.

What's odd is this is the same driver ACI uses in there Titan XL which has always been a downward firing sub with the exception of there custom install subs.

How do you determine if a driver is good for downward firing or not?

[GPM]

You're welcome!

What can I say? I just 'ran the numbers'. I mean they wouldn't be the first manufacturer to post bogus specs and/or sell off drivers that didn't meet spec, if either is indeed the case, so you'll have to ask them their thoughts on the subject, though best of course to design based on measured specs of your drivers.

http://web.archive.org/web/200210210...rientation.htm

GM

[sub_crazy]

I just moved the dual SV12 sub off of the Mal-X and placed it right next to it.......still too lazy to move the Mal-X

I also had to re-run my SMS-1 and made a few slight adjustments.

This sub has just gained a lot more slam and sounds a lot more tighter now that it is on the floor! I am now actually thinking that if anyone who is contemplating getting the Mal-X should really consider about 4 of the SV12's and still have money left over! So much easier to drive than the Mal-X which likes a lot of power. I won't be able to play with the subs anymore tonight but have some free time tomorrow in the morning to compare. I know the Mal-X is still better but if I used 4 of the SV12's I am pretty sure it would beat a single Mal-X and cost less.

I should order a couple more before madisound sells out.

[GPM]

Yeah, amazing what an extra ~3 dB in the mid-bass can do. I took a look-see at what four drivers and 500 W would get me and once a bit of room/boundary gain is factored in, the vented alignment has enough to knock the plaster off the walls with LF and modulate breathing, heart rate in the mid-bass.

GM

[sub_crazy]

GPM wrote:

Yeah, amazing what an extra ~3 dB in the mid-bass can do. I took a look-see at what four drivers and 500 W would get me and once a bit of room/boundary gain is factored in, the vented alignment has enough to knock the plaster off the walls with LF and modulate breathing, heart rate in the mid-bass.

GM

What did you come up with size and tuning to knock the plaster off

Fun driver's so far and yeah that extra mid-bass punch is the icing on the cake.

[sub_crazy]

I put the Mal-X back into action today and yeah, like expected it is better. At more than 2 1/2 times the price of the SV12 pair it should be though.

I could really be happy with 2 enclosures with 2 SV12's in each though and the PLX2502 would drive them easily. The Mal-X on the other hand can run out of juice with the PLX2502 bridged so I use a PLX3402 with it and never have any problems.

I like using multiple subs in my room as it evens out the bass in the entire place. I was planning on using the second Mal-X I have but don't have another 3402. I am thinking maybe a pair of SV12 dual boxes and the single Mal-X is the way to go.

I like these drivers with X-max galore such as the Mal-X and TC-3000 but they are such power hogs and I only have 1 dedicated 20 amp circuit.

[GPM]

I did what I call a max flat impedance vented alignment which has a relatively wide/flat vent output to protect the driver down low against over-excursion.

Anyway, the sim is (4) drivers/(4) vents in a single cab tuned to reach Xmax with a total of 500 W (125 W/ea.), though of course they can be split into two or four cabs. The yellow trace is them in a same size sealed cab for comparison. The sub 20 Hz output is enough to do plenty of damage (been there, done that).

GM

[sub_crazy]

GPM wrote:

I did what I call a max flat impedance vented alignment which has a relatively wide/flat vent output to protect the driver down low against over-excursion.

What kind of dimensions on the port are needed or could you show the vent tab from WinISD? I wouldn't mind making one of these when the weather cools down.

Thanks for commenting with some very interesting tid-bits.

[GPM]

You're welcome!

Actually, I just selected the nearest diameter (4") that calc'd a ~ 5% vent mach (~17 m/s) at ~35 Hz/desired power as a 'worst case' scenario, a rule-of-thumb arrived at by the pioneers of audio through much experimentation in Bell Lab's anechoic chamber, though they didn't define it as vent mach, group delay or anything else for that matter beyond it being required for 'good port efficiency'. Much Later, Richard Small (the 'S' in T/S) arrived at a similar percentage.

Note the 'desired power' consideration. For good performance the vent mach ideally needs to based on the most power it's likely to 'feel' near/at resonance (Fb), so in reality with a tuning this low combined with room gain (assuming it's not well away from any walls, corner, especially in an acoustically large room) the vent system can be considerably smaller and still be 'quiet'/efficient.

Anyway, I have no use for more sub drivers even if free for the asking, so strictly a 'what if' for me, but hope you do try this alignment and report back since all the ones me and others have built were much higher Fb prosound oriented mid-bass bins optimized for 'slam'/'punch', so curious if they can do well in at least some music/HT 'sub' apps.

GM