DIY Comparable to the SB2000? - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 12 Old 01-27-14, 02:53 PM Thread Starter
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DIY Comparable to the SB2000?

Seeking advice on what small sealed sub I could build that would compare favorably to the SVS SB2000 that was just released. Wife wants something a little less intrusive that my PSA XV15 I have now and I was going to get a single SB2000 now and then add a second later on down the road.

However, I was thinking I could get one the 12" Dayton Ultimax kits with either a 500w plate amp or a 1000w or 1500w Crown or Behringer amp and then add a second kit soon after. My question is how would these compare to the SVS? I know I would need some form of DSP to boost the low end just like the SB2000 has. Does another 12" driver model better than the Ultimax?

Thanks for the help.
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post #2 of 12 Old 01-28-14, 02:02 AM
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Re: DIY Comparable to the SB2000?

The recommened box size for the 12" Dayton Ultimax is 2.0 cubic ft. (net internal) with 1 lbs. of Acousta-Stuf polyfill. With the proper amp this would definitely be comparable to the SVS SB2000. Plate amps have a subsonic filter which cuts the low end below the filters frequency. A pro amp without a subsonic filter would offer the most output the sub is capable of. Since your goal is to eventually have 2 subs I would suggest the iNuke 3000DSP with a sub connected to each channel.

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post #3 of 12 Old 01-28-14, 09:37 AM
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Re: DIY Comparable to the SB2000?

the 12 inch Dayton ultimax would be PRETTY comparable as Mike said, but I'd give it a little more "ooomph" than the amp that SVS puts in theres. the Inuke would do great for that purpose.. then you could add a second later on.
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post #4 of 12 Old 09-20-16, 09:57 AM
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Re: DIY Comparable to the SB2000?

Hi - so I am trying to revive thread that has not been touched for nearly 3 years! I have been reading a ton of material over the last couple of weeks and have finally got a few questions to ask people much smarter than me. I am trying to get 2 subwoofers into my rather small HT/music space - intended for 80% music, 20% movies. The room dimensions are 4.7m x 4.3 m x 2.6 m - 52^m3 (~1800 cubic feet). I had initially identified a pair of SVS SB2000s to do sub 80hz duties, I am trying to determine though if there's something I can DIY. I have recently completed a pair of Poor Man's Strads by Troels Gravensen, and am feeling brave!

The challenge I have with doing DIY is getting anywhere close to the size vs. performance (specifically F3) of the SB2000s. Any 12" I model in Unibox or WinISD seems to have F3s in the 40 cycles range, and 15" still don't seem to get close whilst being approximately twice as large. What am I missing here? I have kind of surmised that using a DSP (either in an inuke or the MiniDSP) I can bump up the in-room response curve. But that seems counter intuitive to conventional wisdom - as in response humps are EQ'd and nulls are left as is. Is there some other thing I am not considering?

FWIW - the drivers I have looked at - 12" - Scan Speak, Dayton HF and Ultimax, rythmik audio. 15" from Dayton - HF and UM. I live in Poland so getting some of the other drivers will be a PITA, especially considering that with local prices - 2 15" Utlimaxes + inuke 6000 dsp will already cost nearly as much as 2 SB2000s.

Thanks a ton for your advice!
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post #5 of 12 Old 09-22-16, 08:48 PM
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Re: DIY Comparable to the SB2000?

I think it sounds like a pair of sb2k's are the best choice given room size vs cost vs pita vs time etc. I had one in my theater (with 2 other bigger subs). The sb is an amazing little subwoofer and when you consider the driver and dsp and the fit and finish, IMO, you'd have a hard time duplicating it. If you had a bigger space, like 5000cuft(arbitrary) it might make more sense to go DIY. And don't forget the warranty! Might be worth an email to SVS. That's free at least.


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post #6 of 12 Old 09-23-16, 08:36 AM
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Re: DIY Comparable to the SB2000?

Hi skyflexion,

welcome aboard.

Quote:
skyflexion wrote: View Post
The challenge I have with doing DIY is getting anywhere close to the size vs. performance (specifically F3) of the SB2000s. Any 12" I model in Unibox or WinISD seems to have F3s in the 40 cycles range and 15" still don't seem to get close whilst being approximately twice as large. What am I missing here?
No driver is going to have an F3 of 19hz in a sealed 1 cu ft box, even the Peerless XLS variant used here. For that you need EQ, either analog or digital.

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I have kind of surmised that using a DSP (either in an inuke or the MiniDSP) I can bump up the in-room response curve.
That is correct. Attain flat to 19hz -3db free field is nice, but in the end, the in room response is what matters most. That is what EQ is for. You might be able to apply less boost to attain satisfactory levels at 20hz once room gain based on placement is determined.

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skyflexion wrote: View Post
But that seems counter intuitive to conventional wisdom - as in response humps are EQ'd and nulls are left as is.
I don't quite follow here how this is a problem?

cheers

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post #7 of 12 Old 09-23-16, 12:15 PM
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Re: DIY Comparable to the SB2000?

willis7469 and AJ, firstly thanks ever so much for taking the time to respond.

willis7469 - I agree with you. If I do end up getting something ready made it will likely be SVS and more so the SB2000s. Need to just go down the rabbit hole a little more to see if I cannot match or better them with the collective wisdom of people smarter than me.

AJ - The thought of getting 19hz in 1 cubic foot, even if through EQ voodoo is quite appealing. I could even go up to 2 cubic feet if that helps things. I have been reading up on how a Linkwitz Transform can be implemented through the DSP of the Inukes. If you know of a version of this for dummies, please do point me towards it. Lastly - about the EQs - I have gathered from my reading that the rule of thumb when EQing in-room responses, is that one crops the peaks and does not boost nulls. I understand this is because of potential for distortion. Then in implementing a DSP/LT to boost the low end, am I essentially staying within the zone of not introducing distortion? If yes, is there some key variable I need to keep in mind - cone excursion, SPL, amplifier power etc.?

Thanks all - and have a good weekend!
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post #8 of 12 Old 09-23-16, 04:31 PM
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Re: DIY Comparable to the SB2000?

Quote:
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I could even go up to 2 cubic feet if that helps things.
That certainly would change things, for the better.
In that scenario I would suggest a pair of Rythmik (sealed) GR SW12-4 and compact HX300-12S amps package ($459 ea, so X2 around $900 USD). Use a MiniDSP for EQ.
Free space extension to 14Hz with low distortion and significant output (18mm one way xmax). A pair should fill that room with plenty bass.

cheers
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post #9 of 12 Old 09-23-16, 11:46 PM
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Re: DIY Comparable to the SB2000?

Flat response down to ~19Hz in a small sealed box can be done... the problem is that you generally don't want to. It becomes prohibitively expensive to provide the requisite power to overcome the limitations of the box, both in the size of the power amplifier and in the thermal capacity of the driver. Wood is cheap and air is free, so the logical solution to the problem is to use more of the cheap stuff.

EQ'ing the low end to flatten the response seems like the thing to do... but remember that when you bump the EQ up 3dB, you're asking for 2x the power from the amp. If the box is rolling you off at a higher frequency due to its size, flattening out the response below that point means you're asking for exponential increases in power. Depending on how much output you really want, it's really not too difficult to start seeing numbers easily described in kW for power requirements. In the end, it isn't worth the expense.

That doesn't even touch the issue of fidelity.
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post #10 of 12 Old 09-25-16, 03:46 AM
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Re: DIY Comparable to the SB2000?

AJ and DqMcClain - thank you for your responses.

AJ - Sadly the Rhythmiks are are no go for me. The cost of importing would end up making these significantly more expensive than the local prices for dual SB2000s. They do look sweet though!

DqMcClain - I understand your points and must say that I have my reservations as well about EQing. My main motivation though is seeing that SVS advertises an F3 of 19 hz, surely that must be achievable. Your comment on fidelity is interesting, it would be great to know more in the context of my plans laid out below.

I have modeled a Dayton Ultimax 12 in a 1.2 cubic foot enclosure with a LT and a 20hz high pass. With a nominal signal of 100 watts, the resultant peak is about 480 watts. I plan on using an iNuke 3000 dsp and believe that still leaves plenty of headroom. The SPL indicated at 20hz is around 99db. Since i plan to go dual, I hope I can at least go over the 100db mark, though I doubt I will be doing that too often. FWIW - in the local context 2 12" Ultimax drivers + iNuke 3000dsp + woodwork still equates to 35% lesser than 2 SB2000s and that just feels good! So please do let me know if I am missing out on some key variables.

A completely tangential approach - I might be able to get away with 1 large(ish) enclosure - say around 4 cubic feet. I could for example do an 18" Ultimax sealed, with minimal if any EQ. Of course this limits placements options but I wonder if given the size of the room and the fact I could be sitting directly in front of the sub, this is the better way to go. Somewhere down the line I can imagine moving into a much bigger space and getting another one of these. I realise that this might be an apples to oranges situation, but such are the vagaries of trying to negotiate with my SO.

Wanted to add that these particular models of Rhytmiks are not available locally and also that my split of music/HT is about 80/20.

Last edited by skyflexion; 09-25-16 at 04:02 AM. Reason: Adding context
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