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JeffLearman

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About JeffLearman

  • Birthday 08/11/1957

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    software engineer
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    Seattle, WA USA

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  1. Thread winner. "No, but I bet your sister will!"
  2. It can be done with an analog matrix, i.e. op-amps, potentiometer, maybe a mixer if you can set it up. If the SS is adjusted with an equal mix of mid and side, (presume a 12 o'clock setting of the Width control), then matrix is: L' = 0.5 * (L+R) - m*L R' = 0.5 * (L+R) - m*R where m is the remote mid-side mix ratio, and 0 <= m <=1. The output of this matrix L' and R' become the L and R inputs to the SS. Details here. A nifty little project for the DIY type. This circuit has terminals for external loop (like an FX send/receive, where the signals are Mid and Side, so you could for example put compression on one but not the other). For this use, you'd simply put a width control here, which is just a volume knob for the Side channel. With passive attenuation you'd get at most 100% wide; with any gain in the external loop you could get more than 100% width (which I bet most folks wouldn't want anyway, but you never know what might work best at a given location.) The circuit could be simplified considerably if you just wanted a width control pot, since you wouldn't need the insert tx and rx buffers, and since you wouldn't need balanced signals at that point. Or, for "only" $600, Avenson Audio Mid-Side Stereo Processor (no EQ, though). A remote control would be nifty indeed, but seriously, most of us wouldn't want to pay the price bump that would require. The simplest implementation would be two stereo loops that provide external access to the Mid and Side channels, which you could supply a box to control width (simply by changing volume on the Side channel) and EQ (which presumably you'd apply equally to both channels, but who knows?) You could do that with the simplest little 2-channel stereo mixer. But it'd either mean four jacks, and you'd have to use four cables, if you want it balanced. With unbalanced, you could simplify it to two stereo TRS cables, but no standard mixer uses that so you'd need adaptor cables (fortunately, those exist; they're called recording insert cables.) Either way, it would mean adding two or four jacks, and 4 buffer amps to the SS3, for a feature few people would use. However, if you wanted to mod your SS3 to do this, it might just be possible, if you could find someone to do the engineering. That'd be above my pay grade.
  3. The first question is, are you good at making speaker cabinets? It's nontrivial. If you can make a great speaker cabinet, then chances are good that with experimentation, you can make a great mid-side speaker too. Even if you do make a great speaker, don't expect it to work out as well as what someone spent years and countless hours perfecting. But it may well be way good enough! You'll definitely get the stereo effect. This is the most straightforward way, but you can also do it with three mixer channels: 1 - keys right, panned left 2 - keys left, panned center 3 - keys right, inverted and panned right Mixer left output is center channel, mixer right output is side channel. Depending on the pan law used by your mixer, you may need to adjust faders to balance it properly. The benefit of McGee's approach is you set all faders the same. In either case, you can use the mixer's right (side) bus fader to control width. Right. As mentioned above, you could use two back-to-back with one inverted. If you use just one, it'll still work, though. Just not as well, and folks to the back side of the side driver get cheated out of the high frequencies in the stereo image, unless you're bouncing the side speaker off a nearby wall. The SS3 would be way more convenient and sound better, as is usually the case compared to a "poor man's" solution.
  4. Great idea, but I don't think that's quite the right part, since it's designed for power signals, inside a speaker, with tweeter attached as well. If you don't connect a tweeter, it'd have different response than designed, and I suspect other issues (left-right crossover, shielding, etc.) Plus it's way overbuilt for a line level signal.
  5. Bingo. When using a sub, you don't need a crossover if all you want is more bass. But you can get more volume in the midrange if you use a crossover. U\Yeah, but unless the mixer has separate outputs for subs and SS3, with independent EQ (or by using additional channels to do that), the mixer won't get as much max volume out of the system, as using a crossover. The basic idea is simple: To get the max output from the system, don't make the SS3 carry the bass load, so it can go louder in the mids. To do that, you have to roll off the bass upstream of the SS3. It's nice that the Behringer has this feature built-in. They get maligned for a lot of things, but they're pretty damned good at picking useful features to put into an inexpensive package.
  6. I'd expect that with a traditional stereo rig too, though it might be more pronounced with CPS, especially if width is dialed up to provide a wider field than in comparison to the stereo setup. It'd happen in mono too, though perhaps only for lower notes. I'm not sure of the cutoff, but I remember playing a lower note and walking around with an SPL meter, and no surprise, the readings were all over the place. (With a single speaker.) As you say, that's the room. The whole idea behind nearfield monitoring is to minimize this, so reflections are diminished dramatically in comparison to direct (keep close to the speakers and keep the speakers as far from walls as possible). The CPS concept takes advantage of the reflections, and as we all know, there's no hope of a nearfield monitor situation in a live gig! My experience is that even when there are cancellation spots due to stereo field, our brains are remarkably good at not just filtering that out, but rather, using it to provide a richer image. Cancellation in the room happens with acoustic instruments too, no speakers necessary!
  7. Aspen, that's a good summary. I agree that keeping the front facing speakers close together is a good idea; that was my first reaction when someone mentioned using a pair. I'd still recommend that anyone experimenting with stacking them that way should try reversing left and right cables for the top unit. The result when not reversing them is more complex, and for that reason might be more pleasing (especially to someone like me, who prefers image complexity to image accuracy, in my keyboards). But it would also vary more depending on the location details and the characteristics of the venue. It's not a "try it once, pick what's best, and forget about it" kind of thing; results will vary pretty dramatically. I also suggest that results will vary pretty dramatically when using it on its side. I can see how that would solve a number of problems, but it would also rely a lot on room asymmetry to deliver a stereo image. In any case, folks, I ignore the ad hominem arguments and focus on the subject, and no offense taken where none is meant, so no worries there. It's a forum; we say what's on our minds, and that's how it works. Hopefully we try to have a little empathy too. If the one without sin casts the first stone, it sure won't be me.
  8. OK, thanks. If you wouldn't mind, what's the distance between the centers of the two side drivers, when stacked? If it's about a meter, then the cutoff frequency is around 225 Hz, though I'm not sure I'm figuring that correctly. I'm using a calculator for the distance between woofers based on crossover cutoff frequency, which ain't quite the same thing but should be in the ballpark. (Thanks, MathOfInsects.)
  9. Can you point me to the theory here? This isn't a challenge, I just want to understand.
  10. Regardless, recipes using actual measurements are extremely useful for those learning to cook. And while it may be simpler to try something and then move on, isn't it helpful to suggest things to try that haven't been mentioned, and give reasons for it? Frankly, if the best advice is "try it and move on," then there'd be a lot less discussion on this forum. Regardless, feel free to ignore my posts. I've learned things from you, but if you feel you have nothing to learn from me, that's fine. Meanwhile, this is a free forum, and as long as we're all being polite, there's no harm in discussing all aspects of the subject. We'll be up to 100 pages soon, it's certainly not all interesting to everyone.
  11. Well, let's think it through. The side driveer on the SS3 is open-back, facing left. When the voltage is increasing, the speaker cone will be traveling to the left. This increases the air pressure on the left, and decreases the air pressure on the right. That means that the pressure change to the left side is the exact opposite of the change to the right side. There are various synonymous terms for this: 180 degrees out of phase, inverted, reversed polarity. So, yes, it makes a big difference when you turn it upside down, it inverts the signal. Whether or how that's detectable depends on other things. If you're using only one SS3, it would reverse the stereo image, all other things being equal, that is if the room were perfectly symmetrical. Of course it's not, so the actual results will be diverse, but the image will definitely be different. My guess is "very cool, either way!" (I'm a big fan of nontraditional stereo imaging and spacious sound.) Tombsalley reports that it sounds great with two, one upside down, atop the other. That contradicts my expectations, so I gave it some thought. Here's what I think. When you have two speakers, close together, with the signal to one inverted (which is what you have when you invert one SS3 and set it atop the other), what happens? Well, the lowest frequencies will cancel out dramatically. The cutoff frequency for this cancellation is a function of the distance between the centers of the two drivers. If that distance is zero (physically impossible), the cutoff frequency is infinite: the two cancel out completely. Above that cutoff frequency, things get more complicated. You get a comb filter effect. Frequencies where the wavelength is double the distance get nearly 6dB louder. As the frequency rises, the signal strength decreases and hits nearly zero midway between that frequency and twice that frequency. [PS: this is an oversimplification, since it depends on where you're listening.] And then the cycle repeats. This might sound great on Hammond and Rhodes, but not so much on piano, if it was happening to the main signal. But it's not happening to the main signal; it's only happening to the Side signal. In most cases, the Side signal has very little low frequencies (otherwise that sound would have serious issues when summed to mono.) I think that's what keeps the phase-reversal issue from causing serious problems. I suspect the best test of my guess would be to use a sound that does have lots of low frequencies on the side channel, like Rhodes stereo vibrato (or any significant stereo vibrato). What I'd predict is that unless you reverse left and right cables on the top (upside-down) speaker, the bass will tend to drop out when the vibrato is panned far to either side. That said, I like Rhodes stereo vibrato best when it IS messed with. The best cases I ever heard were when using a satellite cabinet that was vented to the back, and not placed in a traditional stereo setup. So, while the experiment might show a big difference between what's "theoretically best" and other options, the theoretically best won't necessarily be the favorite option. After all, we all love tube amps, despite the fact that modern transistor amps are "theoretically superior". I'm not suggesting we ignore what our ears tell us. I'm suggesting we consider the possibilities. For folks who don't want to think critically or apply what we know about the nature of sound to the SS3, feel free to ignore my posts. If anyone can point out errors in my arguments, I'd be delighted to learn from it.
  12. Good point, but physics is physics, and if the side speaker is L-R, and you put one atop the other upside down, then you really want to reverse left and right in the upside down one. Someone prove me wrong on that.
  13. Do you reverse Left and Right on the upside down one? If not, your Side channels will be 180 degrees out of phase, and the spacer won't help much unless it's REALLY long. Forget time alignment! Frankly, based on how the SS3 works, I doubt time alignment is important at all, since it depends on that side channel being bounced around the room, so time alignment with *what*? Folks say they use them outside, but my guess is that one would sound mono outside, when you're directly in front of the front facing speaker. As you circle around to either side, the stereo image will build until you're about 45 degrees off center, and then begin to collapse, disappearing when you're 90 degrees off center. That's assuming nothing for the sound to bounce off of, but of course there's always something. Put one alone in the center of a wide open space, play some recorded material, circle around, and tell me whether I'm right! Frankly spoken, your flippant dismissal of the benefits of CPS "time alignment", and even moreso of someone who is actually using the SS3 in live application and in so doing sincerely sharing his results with a large audience here who have an honest interest, leaves me a bit cold. Sorry, but my understanding (based on what I read at your website) is that indoors, it works thanks to reflections. When reflections come in, time alignment (between center and side) goes out. But that's a generalization, and certainly time alignment between frequencies in the same signal (front or side) do matter, and getting the drivers close together is definitely a good idea. But only if you reverse left and right; otherwise the upside down one will be sending R-L right next to the rightside up one sending R-L. If the two were perfectly aligned, that'd be R - L + L - R = 0. So, the closer together, the less result. I'd really like to try that and see. I'm not saying I know. I'm saying what the theory suggests to me. I strongly suggest you (a) discuss it with an engineer, and (b) try reversing L and R in the upside down speaker. OK, I'll buy that, thanks. However, I wonder how we're hearing the side channel, outside, when directly in front of the front-facing speaker. Without any reflections, it has to be relatively quiet, and coming from almost the same point source as the front speaker, and therefore providing little image. That's just thinking through it; if I'm wrong I'd sure like to know why! Absolutely. But it's also very easy to fool oneself. Well I remember when several very highly respected audiophile reviewers claimed that CDs sound better if you use a green magic marker on the ring. (I'm not equating results here with that: I'm just showing how easy it is even for very careful listeners to make mistakes.) So, when experience contradicts what I'd expect from theory, I'm interested. It's a learning opportunity, one way or the other. Mid-side is a time-honored technique and a lot is known about it. But applying it to speakers rather than mics or intermediate processing is brilliant! I wish SS3 all the luck. I respect the judgment of the guys here who give it high marks, so clearly it's very well designed and put together, in addition to being a great idea. Regardless, when something doesn't seem to make sense, I'm going to point it out. Sometimes I'll be right; sometimes I'll be wrong. Nothing new there, either way!
  14. Do you reverse Left and Right on the upside down one? If not, your Side channels will be 180 degrees out of phase, and the spacer won't help much unless it's REALLY long. Forget time alignment! Frankly, based on how the SS3 works, I doubt time alignment is important at all, since it depends on that side channel being bounced around the room, so time alignment with *what*? Folks say they use them outside, but my guess is that one would sound mono outside, when you're directly in front of the front facing speaker. As you circle around to either side, the stereo image will build until you're about 45 degrees off center, and then begin to collapse, disappearing when you're 90 degrees off center. That's assuming nothing for the sound to bounce off of, but of course there's always something. Put one alone in the center of a wide open space, play some recorded material, circle around, and tell me whether I'm right!
  15. Which is funny given that he recorded it originally. Not really. 30 years had passed since the original recording and the video you posted. Have you heard the vocal range change in Billy Joel, Paul McCartney, or just about any other singer with a long career? When I heard McCartney at age 60 I was amazed at his ability to sing a LONG show with hardly a break (actually, NO break other than a quiet section in the middle), singing songs in the same keys he'd recorded them in his 20's. Bad example, in that case. Maybe now that he's 70 (or close) he's lost some range.
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