I have recently purchased an SMS-1 to use with my Anthem AVM 30 and have a few questions/comments.

My system consists of the following :
- Anthem AVM 30
- Sherbourn 7/2100
- Velodyne SMS-1
- Rocket speakers (760s, 550 IIs, 200, ELTs - 7.1)
- Rocket Sub UFW-10 x 2
- Samsung 941 DVD (SACD/DVD-A)

blah, blah, blah.... and a bunch more stuff not related to this discussion, you get the idea.

Anyway, I currently have an SMS connected to the two RCA sub outs from the Anthem and I then run a stereo RCA cable to the two Rocket Subs, split each with a Y cabel at the sub end. This works, but I wanted to run a single XLR out of the Anthem into the SMS and then the XLR and RCA outs to the subs. AVS'rs seem to think this XLR/RCA output combo will be fine. Any thoughts here?

Prior to the SMS, I ran dual subs using XLR outs. I added the SMS and using the RCA outs, I now have a ground hum. So I need to find and correct that, for now I have lifted the ground to the subs. Does anyone make an XLR Y cabel? This may solve my ground loop hum.

On the Anthem, I have the XO set to 80 for Cinema mode. On the SMS, I have it also set to 80. I have read about defeating the SMS XO and only use the one in the pre. I tried this with less than favorable results. I can get a flat respone with both set to 80. Anyone have better results turning off the SMS XO?

For Music, I run the Anthem in Music mode with XO at 50, Center=none, Rears=none, sub = 2 Super - All Ch Stereo. So, front mains, side surrounds, & Subs. XO at 50 gives me more full range from the mains/sides, XO 50 gives me some Sub action for music playback. I notice that with this setup I cannot get as flat a curve over the XO 80 on Cinema. I guess this is because the Mains are kicking in at 50 and not controled by the SMS, right?

I tried moving the subs around the room a bit, although my placement options are few. They are currently stacked, and this gives me a best results (flater initail curve and more SPL). I tried to seperate them on each side of my display, and the curve went to heck. So they will remain stacked.

I'm sure I'll have a few more Questions related to using the SMS with my AVM as I play with it a bit more. Thanks for the comments.

There's no need to run two RCA sub outs to the SMS-1, since the sub output is mono anyway. I'd run a single cable from the AVM30 to the SMS-1. The SMS-1 does pass signals between the XLR and RCA connections, so you can connect the AVM30's balanced sub out to the SMS-1 and then send an unbalanced signal to a sub. XLR and RCA outs aren't an exceptionally appealing option, but I have seen some XLR splitters.

I'd recommend disabling the SMS-1's crossover and letting the Anthem handle it - having two crossovers in series at the same point is going to get you to a weird place when you consider the two crossover slopes. If you move the cursor to select the low pass crossover setting for the “Setup” preset (in the System Settings menu), press “SELECT” to edit the crossover, and then press “RESET,” the SMS-1 will turn the low pass crossover off.

Also... XLR splitter? Try these:
Sweetwater for $13
Cobalt Cable for $28 (pick 12" and XLR female / two XLR male)
Parts Express splitter box for $25 plus a cable between the SMS-1 and the box

Thanks gonk, I have a 1M balanced cable arriving this week, so I'll go XLR out on the AVM to the SMS XLR LFE input. I may just then use unbalanced outs on the SMS to feed the subs. I wish they had included dual XLR outs on the SMS. (prob in the next release)

I did try to turn off the SMS Low Pass XO during one of my tuning sessions, but I got better results with it on, go figure? I'll give it another try this week after my cable arrives.

Keep in mind that by using the crossover when you're feeding the SMS-1 a sub signal, the LFE track of 5.1 material is being crossed over and anything above the SMS-1's crossover is being discarded entirely. If you leave the SMS-1's crossover on, you might bump the crossover up to 200Hz or so.

Excellent, thanks for the links.

>>If you leave the SMS-1's crossover on, you might bump the crossover up to 200Hz or so.

I can actually turn off the XO on the AVM... rather than set it at 200. But I'd rather use the AVM and turn off the SMS, as curt recommends on AVS.

once I get my balanced cable, I'll give it another try with the SMS XO off.

If you turn the crossover off on the AVM30, you'd need to also turn the sub off and route the left and right channels through the SMS-1 - that way, the LFE track would get merged in with the mains' signals, the SMS-1 would split the signals low and high (80Hz fixed analog high-pass crossover on the high pass output for the mains and the adjustable low-pass crossover for the sub), and you wouldn't have to worry about data getting lost in the crossovers. I agree with Curt from AVS - either disable the SMS-1's crossover entirely for a home theater application like this, or at least push the crossover all the way up to 200Hz.

No, I'm not going to route L/R thru the SMS. I am using all balanced connections on the AVM to the amp and want to keep it that way. I'll keep using the AVM XO and turn off the SMS.

Also, I am finally able to see the value of the AVM notch filter, now that I can graph it on the SMS. I have a peak near 80, so I have applied the filter on the AVM with favorable results.

The SMS is way cool, but I think it brings out the perpetual tweaker in me, never being quite satisfied. My family is growing concerned when all they hear is the SMS sweep tones for extended periods.

Can you comment on the differnt contour values of the factory presets and what affect they have. Default setting being #4, but Custom setting #5 has a different value for contour. Should I leave my default to 4 or go with 5 after I calibrate?

Each preset's contour acts like an extra EQ channel - set the frequency that it's applied at and the amount of boost or reduction. I keep my contour level at 0dB (effectively disabling it).

gonk, I ordered the MIC SPLITTER/COMBINER from partsExpress along with a 15' and two 3' XRL cables. I just can't isolate my ground hum and when I run just one sub with the Velo XLR LFE output, it's silent. As soon as I use the unbalanced outs on the SMS, I get the ground loop again.

The MIC SPLITTER/COMBINER looks like the best option for my situation, giving me all balanced connections from the pre to the SMS, to the MIC SPLITTER/COMBINER and to the subs. I like the fact that the MIC SPLITTER/COMBINER also offers a ground lift switch on the box itself. I'm confident this will solve my problem.

rmassey,

When you have the hum, does disconnecting the yellow video cable cause it to go away?

I use s-video, but I can try to disconnect it and let you know.

--- I just checked, no affect.

The only thing I notice, is when I unplug the unbalanced line from the sub or the SMS, the hum stops. I even tried to lift the ground on the sub and then on the SMS, no affect. I unplugged all the obvious Coax (Sat & ant) from the system, still no affect.

The mic/combiner spliter gizmo arrives on Thrusday, I hope it does the trick.

rmassey,

Not to belabor the point (just trying to help), are the two subs plugged into different circuits? As I understand it, ground loop arises from a differential between two different ground potentials. Thus, plugging two devices into one phase on one circuit avoids that risk, but two different phases or circuits introduces the risk. I sure hope the problem is not that use of one balanced and one unbalanced input introduces that risk because that is precisely what I had planned to do. Let us know how the splitter works out.

no problem Chessman, I'm happy to discuss/try different things to cure this. thanks for your interest and comments.

I have both subs plugged into a panamax 5300 via a good quality 3 prong grounded extension cord, along with the SMS and all my other gear.

The subs are about 11 feet from my rack, hence the need for an ext. cord.

Also, sorry about the use of my rmassey99 ID above.... I had a bit of a password problem last week and created this temp ID to contact the mod. I mistakenly posted replies with this ID, meaning to only use my rmassey ID.

Sorry for the confusion.

The results are in..... not good.

The PE mic combiner/splitter is crap. It did not get rid of the hum at all, in fact it made it a bit worse over using 1 XLR and 1 RCA output on the SMS.

Not only that, but it totally jacked my previously flat curve introducing some kind of mega noise into the signal.

This thing is going back to PE.

gonk, no worries on the recommendation, I had to give it a try. I was hopeful, but I guess you cannot use a $25 part on a $600 audiophile unit and expect positive results.

I wonder if a splitter cable would give better results (less in the signal path)?

I wonder if a RCA to XLR single cable would work out. I'd use the RCA out on the SMS to XLR in on the sub, eliminating the use of RCA in on the sub.

I have some cables here and will give this a try today.

Problem solved.... I picked up an XLR Y splitter from Guitar Center for $15 (similar to the Sweetwater link above). Both subs are all quiet and flatness has been acheived

OK, now I can get more into the SMS and dial it in without distraction.