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Discussion Starter #1
I received my Mal-X (Gen 1) and 2 PRs a few weeks ago and have been struggling to get started. I would love some help and direction from some of you other DIYers.

I am comfortable building the box and doing the work, I am clueless with design and proper electronic setup (ie HighPass Filter, 2/4/8 Ohm wiring).

It might be helpful if I describe my current setup. The room is dedicated and completely sealed, but a little on the small side (11'x17'). The room is in my basement. The front wall and corners are treated. The first reflection points are treated. My preamp is an anthem D2 with automatic room correction. My speakers are Paradigm Reference Model 60. I currently have two subs: Paradigm Seismic 10" and Klipsch KW1500 (15" - lower power).

I have decent frequency curves for the bass (I can attach graphs if helpful), but I find the bass in the room lacking - no punch - cannot "feel" it. What seems odd to me, is that if I go to upstairs to the main floor, the bass is shaking the house :scratchhead:. This puts me where I am today, building a Mal-X and hoping to fill the room with powerful bass.

At first, I did not think cabinet size was going to be an issue for me. I went to work in Sketch-Up (never used before) and started designing a 30" cube. After I finished and took the design into the room, I could not believe how "big" a 30" cube actually is. I went back to the drawing board and designed a new box that is 26.5x26.5x27.25(h). These are outside dimensions. The inside dimensions are 23.5x23.5x25.25. I will post some of my sketch-up pictures.

Is this cabinet too small? Is it a poor design? Although I have WinISD, I am not sure how to use it to tweak the design.

I will have many more questions, but I need to ensure I am on the right track before I start cutting wood.

Thanks
Darryl
 

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Discussion Starter #2
Here are some pictures from Sketch-Up of my current design.

Although I have been reading these threads for months, I have never posted before thus my ability to post pictures is limited by my knowledge and post count. I will add one at a time until I get the hang of this.
 

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Discussion Starter #4
These are my calculations for volume: 23.5 x 23.5 x 24.5 = 7.83 ft3 - .2 (sub) - .175(pr) - .175(pr) = 7.28 ft3 of volume. This is before any deductions for internal bracing - if required.

Is this slightly too small? I thought Kevin recommends 8 - 10 cubic feet. Will I notice any degradation in performance with this size?

Thanks
Darryl
 

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I'd do some simulations but I'm busy working! (can always find time to make a new post though! :D))

I think you can put some fill in that box and make it look larger than it actually is, from the driver's and PR's perspective.
 

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No... your fine as long as you have some sort of EQ. I'd highly recommend the Velodyne SMS-1 simply because you need the subsonic filter anyway and you get a competent room measurement & EQ to boot. It won't matter if your box is a couple dB down @ 20Hz compared to a "perfect" box simply because the SMS-1 will equalize the room response anyway. As long as your close, the SMS-1 will bring the rest into alignment.

I had this saved already. This is the GenII parameters but it shouldn't be night & day difference and with the SMS-1 any differences are a moot point.

This is 7 cubic feet internal, 25% fill and a subsonic filter running @ 16-17Hz with a Q=1.0 and 1000W simulated.





Kevin Haskins
Exodus Audio
 

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Discussion Starter #9
Thanks for the reply Kevin. Is that simulation for a Mal-X GenII with 2 PRs or with a sealed box?

I am definitely confused about EQ and subsonic filter. I currently have built-in room correction in Anthem D2 that is supposed to be very good. It corrects down to 5Hz (at least that is what I have been told). Attached below is my current frequency subwoofer response curve.

Without knowing much about SMS-1, I am unsure what it would add. On an Anthem thread it was recommended to Warpdrv (who also owns a D2 / SMS-1 / 3 Mal-X) to turn off all cross-overs, eq, and sub-sonic filters on SMS-1 or remove it from the signal path. I think Warpdrv left the SMS-1 installed with subsonic filter turned down as low as possible (4hz) and is using it to boost the lowest levels.

I am unsure if the Anthem D2 will protect as a subsonic filter. I still have to do more investigation. Besides the SMS-1, I am unaware of other more cost-effective solutions as the SMS-1 that you sell is not that expensive. Is it true that I will have different requirements for subsonic filter than Warpdrv because he has sealed cabinets and mine will be dual PR?

Thanks
Darryl
 

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I don't know anything about the Anthem, but from a FR measurement, it doesn't have any way of knowing where a subsonic filter should be set. At the very least, your going to need a way to fix that filter to protect the driver.

This is a common question and the answer is that there is the box that Elemental Designs sells, and there is the box that Bob @ Creative Sounds sells. I've not used either so I don't have any feedback on how effective they are. Both are more than $100.

Having said that, I've not seen a processor based EQ system really get the subwoofer right yet. They set delay, levels and have some EQ ability but they hide the results from you. You take it by faith that they actually got the measurement & EQ right. I just wouldn't trust a device that doesn't show you the results of the unequalized measurement, and allows you to manually fix the response.

Most people don't understand how to take advantage of the room measurements. If your smart, you can use them to optimize the spot for the sub, and the listening seat. You can also take multiple measurements across your listening area and equalize the common problems. Most software algorithms are just too simple to accomplish the task and I wouldn't trust them to get it right.

In terms of sealed boxes, you won't need a subsonic filter for a sealed box because the box acts as an acoustic filter. It rolls of the response for you and protects the driver. In any resonant system (Passive Radiator or Ported box) you need an electronic filter to accomplish that task. Otherwise the driver is easily over-driven under the tuning frequency. If you don't set the subsonic filter right, or if the filter is crude and setting it is inaccurate, you can cause more harm than do good. Most of the cheapo filter boxes use a linear pot that changes the resistance of a resistor in the feedback loop of an opamp to set the filter Fc & Q. Those pots are +/- 20% right out of the box. I don't have a lot of faith that the designers have repeatable results unit to unit and a variable knob, doesn't give you good feedback for position. I'd much rather have fixed resistors that are +/- 1% that can be selected via jumpers or a switch. A variable pot is the wrong part for that job and I wouldn't buy a solution that uses a pot for selection of the subsonic filter. It should be highly accurate.



Kevin Haskins
Exodus Audio
 

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Discussion Starter #11
Thanks Kevin

I am starting to see the benefits. After researching and asking a few more questions, I now understand that I will require a subsonic filter. As for additional EQ, I am a little worried I would do more harm than good because of my inability to setup correctly. But correct me if I am wrong with this thinking. If I did purchase an SMS-1 or another device you mentioned, I would get the following benefits:
  • Subsonic Filter
  • Phase Control
  • Polarity
  • Equalization - can optionally determine the level I want to use; auto or manual fine tuning. I could do this on top of the auto-eq done by more processor. So if I want to boost the bottom end a little, I would have complete control.
I can also do this for up to three subwoofers.

If this is true, sounds like this is the direction I should go.

On another topic, are you still recommending the FACE F1200 amp over the Behringher. If I purchase in US, I want to minimize the number of orders. Shipping, Customs and Duty is a killer when ordering from Canada. I also need speaker connectors - we had discussed adding them to my previous order but they were not included.

Thanks
Darryl
 

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ARC has some extremely sophisticated algorithms in its software, it will measure the output of the sub output and will determine where the knee is - measuring where the natural rolloff is and drop off below that.... The D2 also already has built in Phase at 5 degree intervals all the way out to 180degrees. After having the D2v in house for a while now, I am very confident that you could easily forgo the need for a highpass filter and won't drive your sub out of control....

The D2 needs YOU to setup delay by measuring the distance of your sub to LP with a tape measure and putting in the value in FT.

I would say try it out and keep your finger on the volume until you have had some time feel it out...
 

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ARC has some extremely sophisticated algorithms in its software, it will measure the output of the sub output and will determine where the knee is - measuring where the natural rolloff is and drop off below that.... The D2 also already has built in Phase at 5 degree intervals all the way out to 180degrees. After having the D2v in house for a while now, I am very confident that you could easily forgo the need for a highpass filter and won't drive your sub out of control....

The D2 needs YOU to setup delay by measuring the distance of your sub to LP with a tape measure and putting in the value in FT.

I would say try it out and keep your finger on the volume until you have had some time feel it out...
I'll reserve judgement but they still don't have enough information from a simple FR measurement to know where to set the subsonic filter. The knee isn't a good enough approximation. If they took an impedance sweep, that would give them the right information but most of these devices are just working off a FR measurement from a mic.

Also, you need to be able to view the corrected response and the original measurement. Part of the value of the measurement is being able to pick good locations for the subwoofer/listener. There is no such thing as a magic box that can correct for all the acoustical problems in a room. It is a marketing ploy. What we need are tools that can allow us to pick the BEST locations and then the equalization to maximize them. That doesn't happen with an Auto-EQ algorithm no matter how smart the programmer or powerful the DSP.

My general advice is to ignore the DSP guys who make big claims. The problems we have with the room cannot be solved in the electronic domain. The DSPs are great tools but they are not a cure-all and there are things they are just not designed to address because they don't have enough information about the system. Subwoofer protection is one of those things. They have no idea of the capability of the device connected to them. The designer of the device has to take appropriate caution and in the case of DIY subs, that designer is the guy building the sub.

Kevin Haskins
Exodus Audio
 

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Thanks Kevin

I am starting to see the benefits. After researching and asking a few more questions, I now understand that I will require a subsonic filter. As for additional EQ, I am a little worried I would do more harm than good because of my inability to setup correctly. But correct me if I am wrong with this thinking. If I did purchase an SMS-1 or another device you mentioned, I would get the following benefits:
  • Subsonic Filter
  • Phase Control
  • Polarity
  • Equalization - can optionally determine the level I want to use; auto or manual fine tuning. I could do this on top of the auto-eq done by more processor. So if I want to boost the bottom end a little, I would have complete control.
I can also do this for up to three subwoofers.

If this is true, sounds like this is the direction I should go.

On another topic, are you still recommending the FACE F1200 amp over the Behringher. If I purchase in US, I want to minimize the number of orders. Shipping, Customs and Duty is a killer when ordering from Canada. I also need speaker connectors - we had discussed adding them to my previous order but they were not included.

Thanks
Darryl
By far, the highest value of the SMS-1 in my opinion is the ability to see the actual measurements and compensate accordingly (by either placement, or equalization). If your buidling a resonant system, the software adjustable subsonic filter allows you to nail the right setting. You also can correct for small sealed box builds. It isn't a text-book Linkwitz Transform but who cares. The in-room response is what your looking for and you can equalize using 8-bands of PEQ which is plenty to do anything you need.

The SMS-1 is only going to be good for one device. As soon as you move a subwoofer, you need different equalization. Three different subs, in three different locations are likely to need three different equalization curves. If they three drivers are in one box, it acts as one acoustical source. Then you can get away with one SMS-1.

The F1200-TS is a far more capable amp than the EP-2500. I have both and there is no comparison when driving a Maelstrom. The EP2500 is a good value, but there is more capability to be obtained from a driver like the Maelstrom with a more capable amp.

Kevin Haskins
Exodus Audio
 

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I'll reserve judgement but they still don't have enough information from a simple FR measurement to know where to set the subsonic filter. The knee isn't a good enough approximation. If they took an impedance sweep, that would give them the right information but most of these devices are just working off a FR measurement from a mic.

Also, you need to be able to view the corrected response and the original measurement.

My general advice is to ignore the DSP guys who make big claims.

Kevin Haskins
Exodus Audio
I won't argue with you here Kevin.... ARC can and does show the original measurement and the corrected "Calculated" response.... but not the final response, which should be measured with REW IMO.

I can't and won't say ARC is perfect but it is really that good, but 1 drawback of it here is that it doesn't show measured and calculated response below 20hz, and with a room that small, givin it will have enough room gain this particular sub will surely have monstrous output likely down to the lower teens !!! No question that I would also want to protect my investment....

As much as I highly suggest the SMS, I think in his particular situation with how much EQ'ing ARC does it would be an unnecessarily redundant product to be using.... a Simple High Pass filter would be a better unit to use, but what other product out there offers XLR in and XLR out ? That IMO would be all he needs.


Maybe someone here can suggest such a unit, as I never had the need, so I am unable to make such a suggestion.
 

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Discussion Starter #16
ARC has some extremely sophisticated algorithms in its software, it will measure the output of the sub output and will determine where the knee is - measuring where the natural rolloff is and drop off below that.... The D2 also already has built in Phase at 5 degree intervals all the way out to 180degrees. After having the D2v in house for a while now, I am very confident that you could easily forgo the need for a highpass filter and won't drive your sub out of control....

The D2 needs YOU to setup delay by measuring the distance of your sub to LP with a tape measure and putting in the value in FT.

I would say try it out and keep your finger on the volume until you have had some time feel it out...
Warpdrv
Thanks for taking time to comment. I appreciate your input after your experience with the D2, Maelstrom, and SMS-1. I hope you can answer a few questions for me.

  1. are these abbreviations correct: LP= Listening Position and FT = Feet?
  2. I know you have multiple subs (as I will), what did you enter for distance, the average?
  3. It has been a few months since I last ran ARC. I don't remember entering the distance anywhere. I don't remember this being in required for ARC. Is this entered in the D2 speaker setup? I thought those were ignored and recalculated based on the test tones - or are they only ignored for the main speakers - or was I out to lunch?
  4. What are currently using for HP Filter?
  5. Do you still have SMS-1 connected? I understood at one time you were still using the SMS-1 to bump up low frequencies even after running ARC.
I dont often post but I follow closely the D2 calibration thread (as well as the forums in DIY Subs). There are some very helpful guys there. "Bob" (you know who I am talking about) has been a life-saver for me thus far.

Any other direction you can give me will be greatly appreciated. I know you do not have PRs in your cabinets, but you have a wealth of experience with different subs.

Darryl
 

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I won't argue with you here Kevin.... ARC can and does show the original measurement and the corrected "Calculated" response.... but not the final response, which should be measured with REW IMO.

I can't and won't say ARC is perfect but it is really that good, but 1 drawback of it here is that it doesn't show measured and calculated response below 20hz, and with a room that small, givin it will have enough room gain this particular sub will surely have monstrous output likely down to the lower teens !!! No question that I would also want to protect my investment....

As much as I highly suggest the SMS, I think in his particular situation with how much EQ'ing ARC does it would be an unnecessarily redundant product to be using.... a Simple High Pass filter would be a better unit to use, but what other product out there offers XLR in and XLR out ? That IMO would be all he needs.


Maybe someone here can suggest such a unit, as I never had the need, so I am unable to make such a suggestion.
Yea.... a simple subsonic filter is not available. I'd design one but it would have to be >$100 in the volume I'd sell them. It just isn't a viable product otherwise I'd pump one out.

He may be covered with the ARC. I don't have time to check out every device on the market. I have to make recommendations that cover driver protection as well as give people easy measurement & EQ. The SMS-1 seems to do this the best of the stand-alone devices.

Kevin Haskins
Exodus Audio
 

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Hey Darryl....

Yes to both abreviations...

Yes, in the D2 you should be entering approximate values in feet for all speakers and subs... that is hard for me, as my subs are all around me... so I just gave them an average distance. ARC calculates this but I believe it does so with those as perspective and uploads the values taken from the sweeps.

I am still using the SMS-1 to boost the lows and I have taken measurements with REW to come up with the best Freq. point to boost at... I am not using the SMS-1 for a High Pass Filter because my subs are sealed. They already have a natural roll off, so its not needed with a sealed alignment with the back pressure of the box in play.... With your PR sub, as Kevin states here - it would be a good idea to have a HighPass Filter to ensure that your Mal-X doesn't get signal lower then tuning, really low freq's have a tendency to make the driver flop back and forth drastically trying to produce those lows and can go out of control causing smack or dead end and do damage.... you def don't want that, and there is really no insurance that ARC will protect you here... Hence Kevin's strong suggestion of a HighPass... I would tend to agree, nothing wrong with that ounce of prevention for the $$ investment of drivers here.

The SMS works great for me, having it turn on by 12v trigger with the D2v, and running an XLR to the input, and then out to the AMP... It will give you the ability to phase and set that highpass filter, but I honestly don't think you will need the EQ features of it when ARC is handling all that part for you, unless after your ARC sweeps you find that you have a really drastic null somewhere...

The SMS may be a touch expensive, especially for your needs here - but I really love the simplicity of it, and I know Kevin has always givin it a thumbs up as well... If you go that route, make sure you have the latest firmware on that unit - to be assured you don't have the problematic early rolloff of the old firmware. Here is one for sale... http://forums.audioholics.com/forums/showthread.php?t=55569 Chopin Guy is a standup guy... Check Ebay, and Kevin sells them as well....
Lots of used ones for sale with the SVS EQ out now... which is a good unit, but you don't need it.

Hope I covered what you were after....
 

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Yea.... a simple subsonic filter is not available. I'd design one but it would have to be >$100 in the volume I'd sell them. It just isn't a viable product otherwise I'd pump one out.

He may be covered with the ARC. I don't have time to check out every device on the market. I have to make recommendations that cover driver protection as well as give people easy measurement & EQ. The SMS-1 seems to do this the best of the stand-alone devices.

Kevin Haskins
Exodus Audio
It would be nice to have a really simple solution for this, but honestly most people need some form of EQ for their room, so its hard to justify just a simple unit that may not sell...

Again, I agree with you 100%, its not really worth taking the chance that ARC may or may not protect his driver... No one wants to deal with a broken driver, especially if its an issue not covered under warranty = brought on by recklessness... I sure don't want that on my conscience either... :)
 

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Discussion Starter #20
Warpdrv, Kevin
I will give some serious consideration to the SMS-1. I agree that it would be safest to have a HP filter. There is not a huge price difference between it and other possibilities (Reckhorn), especially if I bought used.

I will have to learn how to use the 12v triggers on the D2 at some time. I currently have a number of fans that I would like to turn on at same time as D2. If I buy an SMS-1, I would like to also have that turn on with a trigger.

As for the cabinet size, since Kevin believes it is fine (though not likely optimal), I will start cutting wood this weekend. I plan on 3/4" mdf. I have never cut circles before so that will be a learning experience.

Thanks
Darryl
 
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