philipbarrett

3) 2 subs on the floor side by side. Now you start to see my objections to the stereo subwoofer set ups. Huge lobes & cancellations start to appear, these will change in amplitude & location with frequency.

2) Stacked pair of subwoofers on the floor. Notice that the amplitude throughout the roomhas increased but the coverage remains about the same.

OK, here goes. Sorry Amy I'm taking up a lot of forum space here. I think I'll break this up into 4 posts so hang on to your horses for a mo' Using the Meyer MAPP prediction software, I built a 20' long, 12' high room and placed in it, various combinations of Meyer 700HP, front loaded, double 18s. The type of sub is not critical to the measurements, these are merely used to illustrate the points. All measurments are done at 63Hz with all room treatments turned OFF. 1) Single subwoofer on the floor. Notice the smooth, almost omnidirectional coverage, red is loudest, graduating down to blue for quietest.

Did you tell the sound guy that? It would have made his day. Most of the time we hear complaints: 1) "it's too loud" closely followed by... 2) "crank it up dude" then... 3) "do you know what all these knobs do?" and finally... 4) "I mix sound in my church, how many watts do you have here?"

The speed of sound in air varies slightly due to humidity & pressure differences. But you are correct, the timing differences you are refering to are related to the physical location of the drivers. This can be addressed by either mechanical or electronic alignment. As you say, mechanical is difficult where horn loaded lows are concerned, made more problematic by the fact that cone drivers produce different frequencies at different parts of the cone, the larger the driver, the more pronounced these effects can be. Back when I toured with Noah we would physically align the cabinets using the trusted "by ear" method to achieve the "best" results. Nowadays it's so much easier and more accurate to align using electronics & an analyzer (of course you can use an analyzer to do mechanical alignment too but room resonances are going to make it hard at the low end). Although, you could argue that the mechanical method is better because it uses less electronic degredation in the signal path. You would be a candidate for the cardiod/directional subwoofer trick though, now that's an interesting path. I don't want to become a bore here (too late probably) so if you're interested in knowing more, let me know in a follow up posting.

Subs are unpredictable beast. So often, what works well in one situation completely fails in another. Often these situations look surprisingly similar so why such divergent results? My most succesfull use of subs is in a mono cluster, center placed on the floor. Obviously this is not always physically possible but when I can get away with it, this delivers the most consistent LF throughout the venue. My reasoning is, that the closer to a point source you can make the LF, the less cancellations you will cause between sources. I truly believe that the ear cannot really determine direction below 100Hz (I disagree with the 250Hz theory) so the loss of stereo is irrelevent. Most "pro" system subs are run mono, my only recollection of stereo subs was the Showco Prism system which used a frequency dependent filtering system to achieve a very even coverage. If I move to left/right sub clusters & flown clusters I can get great results but they become very location dependent. The wavefronts in reinforcement are impressive, the ones in cancellation leave a huge hole. Moving a few feet changes everything so it's hard to deliver solid LF to every seat. As for the time-alignment, in a typical PA rig the subs are physically ahead of the main system by virtue of floor placement against flown cabinets. I have never really been able to accurately measure this relationship as the conditions in the typical venue render measurement at those frequencies, well nigh useless. However, I have experimented with adding delay (very easily done while walking the room with aDolby Lake processor) and have certainly found that I can move the perceived LF power around a little using this technique. However, the effect is subtle at best & of course is highly frequency dependent, what works well at 40Hz can fall down at 80Hz as the wavelengths change. As usual with sound reinforcement, you go for the best compromise. You have the advantage that you know where you want your subs to sound best plus you've found a delay setting that works for you. I think the Behringer DCX2496 crossover would be the best value for your needs. They run around $250 and are designed specifically for this. I would only use it on your subs, leaving the mid/hi outputs unused, plus you can use it to equalize some of the inevitable room anomolies out with a high degree of accuracy. As for your question about speaker delay, you're only looking to delay the subs relative to the speakers. As long as the subs were "early" (which according to your previous set up they were) then you don't need to touch the mains. Delaying the mains at 10ms and the subs at 13ms is no different than zero timing the mains & running the subs at 3ms. However, without starting a flame war, below 100Hz, a single mono sub source may solve all your needs for free. What you are hearing is the cancellation of your stereo subs at 10 feet & a combining at 5 feet, this may be caused by the room dimensions but is much more likely the subs working against each other. You are merely attempting to move that combining further out into the room but by doing so you are building a solution that is good at ONE frequency only, if 42Hz combines at 10ms (for example), 63Hz will not due to the significantly differing wavelengths. If you used a single LF source the problem would not be present in the 1st place. Did I bore everyone completely rigid here?

No but my room mate at the time (now my brother in law) was on the lighting crew for that tour, hence my t-shirt. He's not the type musically to appreciate the subtleties of Ms. Hagen LOL

15 degrees of separation, I was just talking about Nina last Saturday to a friend. Probably the 1st time I'd thought about her in 20 years! I used to have a great Nina Hagen, Europe '79 tour t-shirt. People confuse Nina with Nena (her of 99 Luftballon), not the same thing at all!

Wow, they're great. Robbed blind by Sique Sique Sputnick - http://www.youtube.com/watch?v=pk30a0qsVIk I'll see your Kraut pop-electronica & raise you with Klaus Nomi - Of course the shadow of Giorgio Moroder can be seen all over this stuff.

I'd have used the usual reply, "that's nice." Which as we all know is Southern Belle for F**K You! I would have followed that with a good "Bless Your Heart."

I have to throw Daft Punk into the ring here too. Check out Robot Rock - http://www.youtube.com/watch?v=rBbasXXtrXw&feature=channel Or Technologic -

Count me into the reverse club. My K's are driven by a Pilot SA-260 amp which is fed by a Carver C-1. The combination of an extremely quiet & linear source (I SIM'd the C-1 and had a hard time believing the phase & response curves) and a personality filled (ahem) amp works great for me. BTW, you can pick up those old Carvers for very little cash on CL all the time.

I've been enjoying this UK streaming service for about a week now (http://www.spotify.com/en/). This is not your father's web browser based player, imagine your iTunes with almost everything available instantly. It's pretty cool to see an album pop up in the "Right This Minute" thread & within seconds be playing it yourself. As the screenshot shows, I was typing this after browsing the FUNK thread. Thanks to the enlightened morons at the major labels it's not available to US residents (they check your IP address) but those who understand the use of a proxy server & a little googling (you'll need a UK postcode, anyone will do) can get a free account & download the software pretty easily. Once that's done you can log on from the US as normal. Quality is excellent considering it's streaming.

I worked a show with Soft Cell ("Tainted Love") back in the early 80's. Opening act was none other than Mr. Loopzilla his'self. The look of horror on the largely pre-pubescent female crowd was priceless when George strutted out in a black leather cap & red spandex leotard!

Oh I know you could. The horns in our babys are not kind to a harsh D to A conversion as these errors tend to appear right in the upper midrange.

Nope but I could build a pair of wall diffusers, as for the Spousal Acceptance, you got me there. PB

2 seperate subjects. Clocking is the transmission of a digital clock signal embedded in the audio bitstream. This allows the receiving device to synchronize with the sender resulting in a more accurate transfer of the data. Both USB & FW will send the data at the rate at which it is playing up until the limit of the chipsets in the interface. In other words, a 16 bit word will be transfered at 16 bit, a 24 bit at 24. It's easy to confuse real-time data transfer such as audio or video playback with bulk data transfer such as is sent to a hard drive during a back up.

Au contraire. You can build effective room treatments for small $, heck I could build a studio for the price of some Pears. If the room is the problem why would you not treat that first? PB

For all who care -http://lrlrl.coldplay.com/leftright.html I guess I shoudln't look a gift horse in the mouth but be prepared for a horribly thin & lifeless mix.

The Presonus units are very good value too, their small Firebox should work out for you - http://www.presonus.com/products/Detail.aspx?ProductId=4 On the front page it says XP but the downloads section shows a Vista-64 package so I'll assume they're compatible. We use these to deliver the audio from media servers (the boxes that supply the content for the LED screens you see all over TV & tours) since they are a sturdy, reliable unit & seem to be very compliant. I doubt Behringer will release a software upgrade however, it's entirely possible the FCA will work fine with your OS. If you order from Musicians Friend you can easily return if it doesn't.

Yes, bypass the soundcard, the FW carries both signal & power (except for a few older FW ports and hi-current requiring convertors). I'll plug my AKG-701s in Saturday & let you know. Shouldn't be a problem tho'.

Love it, treating the problem (room acoustics) rather than throwing money (cables, doo-hickeys...) at the symptons. The editors of the audiophile rags are sweating right now. Greetings from Big-D & another pair of K's. PB

USB is OK (and clocked) but was never designed for the transmission of audio. Conversely, the IEEE-1394 specifications for FireWire were expressly created for the transmission of high quality audio & video. Back when FW units were expensive USB was a nice cheap alternative. However, today, when a FW card & interface can be had for >$150 USB makes little sense. Comment on the Peachtree Nova : This is still dealing with unclocked signals which will be detrimental to the sound WHATEVER the quality of the device. The USB interface is nice but that's a huge price to pay for a USB device.

I find it amusing that we covet this vinyl so much yet all of it was originally cut on the "audiophile" scourge known as the Direct-Drive Turntable. Apparently, according to the cogniscenti, it's good enough to make a record on but not good enough to play one back! Caveat - I have an SL-1200 Technics & love it.

Agreed, but here's the rub - they make almost any POS system sound pretty good which is a huge compliment to the recordings but only useful if you want to impress rather than analyze.