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Last weeks question: Advice on subwoofer

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cknight

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Re: Last weeks question: Advice on subwoofer

PostThu Mar 10, 2011 10:40 pm

Hey Clinton. What microphone set up did you use with the RTA and was it calibrated for you or did you use a calibration chart for that model? I noticed the roll off at 20Hz and wondered if that was the mic or the sub


Hi, Thomas. Probably some of both. Since you asked, this was the measurement signal chain:

Outputs:

* MOTU 24I/O (20Hz – 48kHz, +/- 0.2 dB). Why 20 Hz? Assume it rolls off some below that.
* DBX 223 active crossover (20Hz – 20kHz, +/-0.5 dB) / (3 Hz – 90 kHz, +0/-3 dB).
* Peavey 4080HZ (10 Hz – 35kHz, +0/-3 dB at rated 4 ohms power).

Inputs:

* Uncalibrated Behringer ECE8000 measurement mic ("ruler-flat from 15 Hz to 20 kHz"). Yeah, right!
* ART Tube MP preamp (10Hz – 40KHz, +/-1 dB).
* MOTU 24I/O (20Hz – 48kHz, +/- 0.2 dB).

So each of these could have contributed a little roll-off below 20 Hz. So taken all together, the sub is likely much better at 16 Hz than measured.

I designed for a 3 dB roll-off at 16 Hz, so given the above, the measured results aren't too far off. For a more typical box I could have tweaked the port length to flatten the measured curve a little more, but for added strength I fixed the port into the structure of the cabinet. Given the likely measurement errors, I think it's not worth tinkering with.

Image

This configuration models 119 dB at 16 Hz with 1500 watts input. Even if the actual value is a bit less, it's plenty.

Image
Clinton Knight
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http://ambassadororgan.wordpress.com/
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toplayer2

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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 6:10 am

Clinton,

It is evident that you know what you are talking about. Although I decided to go with a Trinity, I had considered constructing one or two subs pretty much along the lines of what you have done. The Maelstrom woofers are, unlike the vast majority of large diameter drivers, very suitable for a moderate sized B4 aligned vented box. Advice to others considering home brew subwoofers would be to copy your design exactly. No need to re-invent the wheel.

You appear to have chosen good tools like the TrueRTA and Behringher mic.

http://www.trueaudio.com/rta_down.htm

Your previous post has screenshots which appear to be from a T/S modeling app, but I don't recognize it. What is it?

Link to the Maelstrom site:

http://www.diycable.com/main/product_info.php?products_id=681

For people who do not wish to construct a sub but cannot justify a Trinity (or Thigpen :) ), Craig had mentioned his SVS. The audio community consensus is that SVS makes a good product that is capable of delivering clean bass to 20 Hz. In particular the model PB13 seems to have a lot of fans. The DefTec Supercube Reference is also not a bad option.

Joe Hardy
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cknight

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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 9:42 am

Your previous post has screenshots which appear to be from a T/S modeling app, but I don't recognize it. What is it?


Hi, Joe. I used BassBox Pro for the 4 distinct speaker designs I used in my instrument, along with the related X-over Pro for the two-way designs. I found those tools fairly simple to use, and the speakers generally performed in line with the models.

I'm impressed with the Maelstrom woofers. You linked to the excellent 18" one, whereas I'm using the ridiculous 21" model. Bass is all about moving air; both of these models have a 2.5" stroke and do that very well indeed.
Clinton Knight
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http://ambassadororgan.wordpress.com/
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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 10:04 am

For anyone interested, here is SVS's site: http://svsound.com/products-sub-box.cfm. One thing I liked about them, that gave me some confidence in ordering something I could not audition, was that they published response curves, and explained the conditions under which they were obtained. Guitar Center still sells the m-audio SBX10 sub, and the claim is made it has clean bass to 20hz. I can tell you from experience, and I played with this thing a lot, that is bull. I bought the PB-NSD model, now being redesigned, in part because if it didn't live up to my expectations, I wouldn't be out so much. The response curves for the more expensive SVS units, like the one Joe mentioned, are a little better, but for 2-3 times the money, with some of that going toward nicer cabinetry, higher output, and adjustability. If mine were to be destroyed, I would probably get a plus or even ultra, 'cause I'm not immune to bells and whistles, but the $699 NSD has not disappointed, and depending on how little you are willing to pay yourself, I think it would be tough to build one that good that size. I know it's starting to sound like I have a financial interest in them, but I don't. I just think they can make a better product for less because they don't have an advertising/marketing drain.
Craig
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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 3:58 pm

Hi Craig,
You sure don't sound happy with your GC experience. Not that I have any financial interest in them I will say a couple of things. First, of all the subs you chose I certainly would not have went with that one. Rock bands are not the only customers of GC and they as I can imagine, cater to a very diverse clientele. Many bands are using Hammonds, synths etc., and also not to forget the hip-hop / rap crowd (sorry not one of them) that are getting down to these kinds of lows. GC like most, unless they are testing things themselves (which I doubt) is likely just going off of and publishing what the mfg. claims, and although the mfg. phamphlets are good reading, I take all claims with caution and will research first. I don't know how many times I have read something claiming greatness only to find out it's a bunch of junk. Of course opinions will also vary greatly depending on whom you talk to. You might talk to someone else who bought the same sub you did and they just "love" it.

I think what we are discovering is we are dealing with a very different kind of low, the majority of the subs built are described as having sound that is "explosive" or "hard hitting" or "punchy", all of this maybe great for rock, hip-hop or country, but not exactly what I would describe as a sound from an organ and what I think we would want for features in a sub for an organ. I think what it boils down to is an organ needs an entirely different type of sub, one that perhaps goes a bit outside of the normal parameters of thinking and design. Who has that design? At this time I don't know. I just finished a sub project, since to me bass from an organ is more subtle or non hard hitting, my thinking was to use a larger than normal cabinet, much lower power, less strain and cone flex on the speakers (to hopefully minimize distortion and additional unwanted harmonics), and kind of along the lines of the Thigpen theory use the cabinet size to aid in making the bass vs. just power and speaker size. I just got it going last night, so far I like what I hear. EQ'ing and more adjustments to come. We will soon see.

Thanks,

Marc
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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 6:39 pm

Hi Marc,
I didn't mean to diss GC. I shop there a lot to this day. One problem is that the stores stock a tiny fraction of the products on the web site, and I wanted to buy in the store so I could at least see it before I bought it. The m-audio system I bought is marketed as a near field studio monitor system, and at that time, three years ago, in my naivete I thought studio monitors should be better than regular home stuff. Obviously, I know better now. I made a mistake, and just didn't want someone else to do the same thing.
Craig
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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 6:58 pm

Studio monitors can make fabulous organ speakers. The original Mackie HR824 is more accurate than the "audiophile" speakers I have in the same room.

Joe
Last edited by toplayer2 on Sat Mar 12, 2011 11:01 am, edited 1 time in total.
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Re: Last weeks question: Advice on subwoofer

PostFri Mar 11, 2011 7:19 pm

Hi Craig,
I do as well. Maybe the stores are a little different there than here. We've got a couple of really nice / well equipped newer stores here in the Minneapolis area and is the place to go for things of almost anything musical in nature. Always fun to stop by, look at the latest and see some 12 year old kid ripping away on some hot guitar lead that would make Eddie sound like he needs to go back to the drawing board. I do tend to insist on at least trying to get a listen in the store if possible or search out someone or some venue that would have the equipment being considered for a closer listen. I as well just hate surprises, especailly expensive ones. I mentioned my sub project underway. So far I discovered the cause of an annoying lower boomy-ness was from the 3 ways I robbed the 12" drivers from, I literally had to EQ out before but that is now gone. As I mentioned earlier, I prefer a fairly large cathedralish sound for my HW set-up, I also play at lower volume levels in my just barely 12' x 12 ' office. I am getting that nice slow developing, at a distance soundig bass you can feel and makes the floor in the church shake (and your hair stand on end) and I have yet to touch any adjustments, so now I'm really anxious to dig into it more. By sometime tomorrow I will know more.

My 2 cents on small speakers, I just picked up a couple of Polk Audio T15's, great sounding speakers as well for HW use!

Enjoy your Friday eve!

Marc
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Re: Last weeks question: Advice on subwoofer

PostSat Mar 12, 2011 10:57 am

oops, did it again. I should clarify that in my last post I was not implying that studio monitors do not make good organ speakers. That is too general a statement. I think the little m-audio speakers I bought as part of the set are great. I think we probably all agree that it is not difficult or terribly expensive to find excellent speakers for north of 80-100 hz, but that naturally sounding low pedal notes are much tougher. I wasn't familiar with the Mackie HR824, so I went on their web site. Wish I had them. It is interesting that their subs are advertised for stage use, and that even the 18 inch frequency response would not do for organ.
Craig
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Re: Last weeks question: Advice on subwoofer

PostSat Mar 12, 2011 10:27 pm

Hi Craig,
Not to worry, I didn't take it that way. When it comes to the smaller speakers I think the choices are MUCH easier and I imagine there are tons of good selections out there be it monitors or what have you. I was in need of some better small speakers, I have listened to some nice ones at GC and my brother-in-law has a nice small studio set-up at his home that incorporates some really nice sounding monitors as well (can't remember the brand) but I couldn't swing the prices I was looking at. I stopped by the local Best Buy here and after listening to a number of speakers settled on the Polk T15's. I am really happy with them, they cover an incredible range for their size, sound even better for HW than what I was anticipating based on what I heard in the store so was a nice surprise, and I especially liked the $104.00 per pair price tag.

More experimentation to come on my sub project, I'm not there yet and it's looking like the last few notes below G or so are going to be a compromise. I am finding it is a tricky balancing act between voicing amplitude, bass management through EQ and the soundcard, and the amount of volume going to the sub. I have 3 separate amps and a fourth old tube amp if needed along with a mixer I can throw back in to the mix if needed. Based on tests today it's looking like another reconfiguration of what has been doing what. One thing I have learned with this HW stuff is for the best possible outcome, one needs the ability to individually control the volume and EQ (at least to the best extent possible) of each speaker and amp running them.

Marc
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Re: Last weeks question: Advice on subwoofer

PostSun Mar 13, 2011 1:02 am

Coming back to the original subject of subs. Let's say, forget about real 32' tones and getting down to 16Hz.
Apart from that -- I was thinking about something like the Rythmik Audio's DS1200 (sealed box), for a small room. I am thinking, two pairs of nearfield monitors (1 stereo pair per each wind chest), plus the internal speakers of my old Rodgers console for the pedal, plus one pair for the back. I hope this would achieve a nice sound picture for the organist at the bench. Did any other Hauptwerker ever tried this sort of setup? Will two separate pairs of nearfields -- separated per chest -- provide an advantage?
And most interestingly -- did any other Hauptwerker tried the Rythmik? Are they any good, or is it just their propaganda?
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Re: Last weeks question: Advice on subwoofer

PostSun Mar 13, 2011 10:28 am

Personally, I would be hesitant to plunk down $559 for a driver and amp, then have to find or build an enclosure without any assurance the final product would deliver, when an excellent complete sub can be had for $699 (see prior posts in this thread and the other similar thread). As far as making 16hz a criterion, I agree, because I'm not even sure I can hear 16hz. However, when I pull a 32ft stop, and without changing anything else, the pictures start to rattle and it feels like I'm being puffed with air, I kind of like that. I believe that if the sub can do that, it is likely to be very good at 32hz.
Craig
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Re: Last weeks question: Advice on subwoofer

PostSun Mar 13, 2011 11:59 am

I'm in the same boat, 32hz can happen at home, something below it should as well, 16hz just won't I don't care what you do unless maybe you turn your whole house into a Thigpen set-up and then it still may not happen. If I can get a good decent sound down to a certain level without it distorting or breaking up and sounding really unatural I will be happy and I'm going to leave it alone.

I enjoy that nice larger cathedral sound, I am using 2 stereo pairs (4 speakers on the front channel) off in the front corners and the other 2 nearly directly in front of me, 2 more approx. 10' behind me up in the corners near the ceiling which is 8' high and the sub directly centered on the same back wall behind me. I also used a pair of 3 ways there before the sub which also sounded really nice and I may put them back in use. This arragement seems to give the field of sound I like. One thing that is critical is having the ability to be able to individually adjust the volume of each speker to get the balance just right.

Marc
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