Velodyne EQ - Page 42  

CycloneMike,

Did you try the factory reset? Granted, this would cause you to look all your settings, but it might be worth it.

I don't quite see why they engineered it so that you couldn't get back into the system to turn off the 12 volt trigger.

I have been a succesful SMS-1 user for some time, and posted earlier in this great thread. I am thinking of going to stereo/dual subs, and want to use a pair of SMS-1's (daisy chained, I guess) to EQ both for great 2 channel use. Currently my l/r mains are running full-range and I take a second pre output and run l/r to a single SMS-1. It EQ's a corner located Paradigm Servo 15, and does a good job. I'm eval'ing several different sets of main l/r's and the EQ process for each of them goes pretty smoothly (pun not intended).

Now I think I want true stereo subs, and another SMS-1, and have looked at Velodyne's daisy-chain ideas in the SMS-1 manual (page 11). It's weird, however, in that it really treats the slave as a self-EQ'd "secondary citizen" and primarily tells the user to concern him/herself with the master sub. It says to set polarity, phase and xover for the master, copy it to the slave, then run a simple self-EQ on the slave. After that all the slave really sees via rs232 is volume and preset commands.? What if the sub is not symmetrically located, what if phase and polarity are different (or more to the point, need to be different due to different distances from the sweetspot, etc.). Seems to be a very best-case scenario it sets up.

Net/net, since I don't need a primer on the SMS-1 what I really need is a primer on EQ'ing two subs in one room. As a start, don't they need to be half the volume, or some percentage once both are running together, or does the fact that one main speaker is only running during EQ make up for that? ? How about phase/polarity? Is there a possibility they cancel or wreck havoc on each other's separate EQ settings? To me this is like setting brightness and contrast on a good display, both are synergistic and tied, but not sure where to start. Any help or link or thread reference would be helpful. Thx
Ted

Well you are asking all the right questions Ted. :)

I currently run a pair of EP600 stereo subs and an Ultra LFE dedicated third sub. Getting the phase, FR and polarity is trickier as you've noted and it involves setting each up individually then checking them running in stereo.

First start as you normally would equalizing one of the subs with the other one turned off. Next blend with the main and choose your crossover point , phase etc. Now shut that sub off and repeat the process with the other stereo sub. Then turn them both on. Odds are you will have a less than even FR with both on so you will have to go through the iterative process of checking phase and polarity with each sub while both are playing sweeps to ensure a smooth FR. Take care to avoid cascading crossovers with the processor and the subs which can be problematic. It is more time consuming than running a pair in mono but the resultant air and presence will be noticeable if you get it right.

In my case I also run a dedicated LFE sub along with the stereo subs though I use a BFD with the stereo subs and the SMS with the LFE sub. The advantage of running a dual channel BFD is it allows for adjusting each stereo sub up to 200hz if necessary with the crossovers bypassed while running full range signals. Having flat subs above the crossover point provides some benefit when you blend the mains. Adjusting with the BFD is easily done while watching sweeps on the SMS display. No need for REW. What I am trying to do is equalize each sub as flat as I can before trying to blend with the speakers. I'd say it takes 2-3x as long to dial stereo subs this way so give yourself a good afternoon of uninterrupted time.

Ted - this is pretty much what I did [as per my pm]. As John said, it is time consuming...walking back and forth, checking the display, adjusting the sub, checking the display...on and on and on.

I tried once with my wife home. I learned. I did it for real we she and the kids were out.

The important thing that I noticed, and I am far from an expert, is that the phase adjustments that worked individually when I started were really bad when both subs were switched on. Then, when I got the two working together OK phase-wise, I somehow managed to still get them working well individually with their respective channel. I would have thought that they’d then become messed up individually. I am not so sure what I did with the phase to begin with, but my final results were surprisingly good.

I think it is one of those things you just have to play with on your own. With the SMS-1, it is really not that hard. I can't imagine doing this without one, or some other sort of repeating sweep tone and graphical display.

Thanks both of you. Although neither of you use dual SMS-1's I get the ideas and will give it a try soon. I'm not sure I'll daisy chain, though, probably just hook two up separately.

Ted

With my old Pioneer Elite analog RPTV, the screen did not roll when used with the SMS-1, but when the TV fizzled after 15 years, I replaced it with a Sony SXRD RPTV and the screen rolls at a regular pace--about one full roll taking 2 seconds. Needless to say, this makes calibration of subwoofers MUCH more challenging. Modern TVs don't have any anti-roll settings like the old TVs used to have.

I am feeding the video via S-Video into the pre/pro and upconverting it to component video to be fed into the HDTV.

Any suggestions as to how to keep the screen image from rolling??

MikeSp