Axiom Home Page Forums General Discussion Technical Questions Multiple EP’s, daisy chain or…???

I’m swapping my EP600 out for two EP500’s. This is my first time using multiple subs. My receiver does not have two LFE channels. I use Audyssey, and I like it. So I was just pondering what would be the best way to hook these up. I can either daisy chain them or run two cables back to the receiver. They need to be placed on the front (screen) wall, facing into the room. They’ll be equidistant from the main listening position.

You guys who have multiple EPs have any tips to share?

Michael, yes this can be done, and I also love Audyssey. I've done it with a 600 and 500, and then a 600 and two 350's spread around the room. Before you proceed, the main thing is to calibrate each sub individually. I had them all daisy chained, but that is the same thing as splitting at the receiver, same outcome.

Calibrate Sub 1 first with Sub 2 turned off, so Sub 1 matches the spl of the other speakers, say 75dB or so. Then turn off Sub 1 and rerun the pink noise and match Sub 2 with the speakers. Then turn them both on....

Now, Jakeman helped me and said to calibrate the subs say 3dB lower than the speakers, so the combined slp comes up to where the speakers are. I experimented and think I just calibrated everything to the same SPL. Audyssey will do the rest....

After you run Audyssey the first time around from position 1, you can calculate, and check what it did to the sub levels. If to low or to high, you may have to adjust the receiver level and/or the subs volume knob, then rerun.

Then you can rerun Audyssey from all positions, and enjoy.

Thanks Randy. I wasn't sure if there was a driver for daisy chaining the EP's because of the DSP technology or not. I'll have independent cables run through conduit back to the receiver in the event I buy an AVR or Pre that has provisions for two subs.

If you all ready have the cables ran for two sub I would just split the Sub out with a rca splitter.

I used a 'Y' (Wye ) from the connector at the wall plate to the AVR in the equipment closet ... all of the six runs to the sub outlets are in-wall.

If I'd thought about it at the time and had the chance to do it over again I would have ran a single run to all six wall outlets and T'd off of the main run for each outlet ... would have saved from having six different inputs on the wall outlet in the equipment closet and having to need just that much more cabling.

I'd run two cables and run them off a BFD so that you can equalize them independently using REW.

Nah, I probably wouldn't. I'm just messing with you.

I hope you're kiddin Tom... I don't want to open that can of worms. Yuk, frustration and self inflicted insanity would be the result.

Thanks guys, a Y at the audio processor it is.

Mike, that probably would be the more convenient connection, and convenience is really the only factor to consider, since there should be no audible difference. If the two subs were very close to one another, a short daisy chain connection between them might be the way to go.

Yeah, I think you'll have to use a Y, since the new EP amps only daisy chain on XLR connectors. Don't know that it would work with an unbalanced connector to the receiver.

I guess I did not realize that Axiom removed the ability to daisy chain using RCA's, seems that is making things more difficult?

Well, they could be somehow using the balanced outputs with the unbalanced inputs, but I don't know. Guess we'll have to ask about that.

Good catch Ken. I did not realize that.

I spent a lot of time looking at my replacement EP350 amps...

Since it's been decided to use a Y-splitter from the receiver sub out, the point is pretty much moot, but since the EP500s each have the new inputs, a balanced connecting cable can be used for a daisy-chain connection, as the manual describes.

Oh, manual. Well la de da, aren't we fancy.

Well I haven't hooked them up yet John... It would make life a wee bit easier to daisy chain them, as I wouldn't need to pull another cable in.

The balanced cables are just XLR with one mail end and one female right?

Correct and I believe this should show that:

http://axiomaudio.com/balancedcable.html

Sure, Mike; if it'd be easier for you to use the daisy-chain connection, the most common type of XLR cable, with one male connector(into the second sub)and one female(out of the male XLR output on the first sub)would work. Of course, there're other options: XLR to RCA plug cables are available and a XLR-RCA adaptor fitted to the first sub would allow using a regular coaxial cable with RCA plugs on each end.

All of these connections are actually unbalanced, regardless of the cable used, since if the signal comes out of the receiver unbalanced, using different cables or adaptors can't make it balanced. A balanced connection requires two signals of opposite polarity coming out of the receiver or separate pre-amp.

Thanks guys. I was looking at these, from Blue Jeans. http://www.bluejeanscable.com/store/balancedaudio/index.htm

Interesting information there John. It's obviouse now that you mention it, but I had not thought of it (about not being balanced).

Mike, as usual, MonoPrice is more reasonable.

and nothing wrong with Blue Jeans cable either. You are just paying a little more with better aesthetics

Can someone explain to us new folks what's the difference between calibrating one sub at a time & two together. It sounds like one way you may tune up and the other tune down???

Do you just need to use an ordinary RCA splitter? Or a Y cable designed specifically for subwoofer cables?

A ordinary splitter would work just fine.

Sat, as Ken indicated, all Y-splitters are "ordinary". There are no specially designed subwoofer cables(regardless of seller labeling); all these are simply coaxial cables with an RCA plug on each end, and there would be no need for anything different in other cabling connected to them.

OK just checking, that's what I thought. I don't understand the difference between a coaxial cable and an ordinary RCA interconnect cable (is there one?), hence my fuzziness still.

I couldn't scrounge up a splitter and the(coaxial) cable I have isn't long enough to daisy chain so I used an XLR microphone cable to daisy chain from the new sub to the old. So I am running an unbalanced coaxial cable to the new 800 and then daisy chaining via an xlr balanced cable to the old 800.

Will the balanced XLR connection be a lower power level output (i.e., will the old sub receive less signal) and will that create an issue with balancing the levels between the subs (aside from any other differences caused by different amps etc). On first blush the old sub seems to have less volume but again I am wondering if the cabling might have anything to do with it or not. I'll probably get to calibrating tomorrow but just wondering theoretically if the levels will be different due to balanced versus unbalanced inputs to the subs.

So I put a low Z to high Z (impedance) transformer on the end of the XLR cable, the transformer terminates in a 1/4 inch phone plug, if that's still the term, and then used an adaptor to convert that to an RCA input. Plugging that into the old sub, it seems like the levels are pretty close now.

Sat, another point of terminology is that there are actually no "RCA cables"(despite labeling), since "RCA" is the name of the plug at the ends, not the cable itself. Sometimes the term is applied rather imprecisely to a cable that isn't of the 75ohm impedance suggested for most digital connections.

As I pointed out in the reply to Mike Drew's thread, the cable itself can't make a connection balanced, and in your case both subs are operating with an unbalanced connection, despite the difference in the form of the cables. In a true balanced connection the receiver or separate pre-amplifier has to be able to output two voltages instead of one, with the second voltage being of opposite polarity. These two voltages then ride along the two center conductors(compared to one in a coaxial cable)into the amplifier. If any external interference hits the two conductors it would be nearly equal in amplitude if they're close together and would be of the same polarity. If the amplifier has balanced circuitry, it reverses the polarity on one of the conductors so that the two original signals are again of the same polarity and their voltages add, which doubling of voltage is an increase of 6dB(rather than the 3dB in a doubling of power). The noise voltages however are now of opposite polarity and tend to cancel each other, which is why a true balanced connection has greater interference rejection. If the gain on the balanced circuit in the amplifier was the same as that on its unbalanced circuit the balanced input would result in a 6dB louder level. To compensate and equalize the levels, the gain in the balanced circuitry is typically set 6dB lower. Sometimes if this compensation isn't made, or isn't fully made, the louder result on the balanced input will give the misimpression that it's of higher quality, although it's actually just a volume difference.

Interesting, I think I see that now, I thought the amp in the first sub would allow a balanced output even though the input from the 3808 is unbalanced. Still, if I understand correctly, the xlr input circuitry to the sub is set to a lower gain than the line (rca) input circuitry, no? Anyway the transformer for the xlr cable seems to be working to put the 2 subs in the same ballpark volumewise, so to speak. Otherwise they seemed too disparate in volume as a starting point to conveniently adjust the volumes toward a point of balance.

Yeah, Sat; the receiver/preamp has to have circuitry to send out two voltages instead of one(but of reverse polarity)and the amplifier has to have circuitry to "re-reverse" them. Both units have to have the balanced circuitry provisions. Yes, assuming that the amplifier does have lower gain on its balanced input, an unbalanced signal(without the double voltage)fed into it would result in a lower sound level.

OK thanks, I believe I'm on track now.

Finally got the 500’s dialed in. I don’t know why yet, but depending on which one I turn on first, the sub with the lead from the AVR will not fire unless I turn it off, then back on again. After I cycle this, it fires just fine. I also ended up adding a third sub to this room. I had an Outlaw LF1 which the 600 replaced in the great room, so I figured a third sub couldn’t hurt in this room.

Initial impressions are good. The two 500’s seam to fill the room a bit more evenly. I’m still trying to figure out exactly what it is I like better and find lacking. The 600 on its own seamed to rattle things that weren’t secured properly, like a door. The 500’s don’t do this. When I was running the single 600, I didn’t have anything to complain about, till now. I don’t know how to describe this, but in short, the LFE is just generally smoother. There was a ‘boomyness’ before that is not there now. I did not notice this before, but now I do. The addition of the Outlaw smoothed the LFE out even more. Before, with the single 600, my SPL meter would bounce between 6 and 8 DB (yes, C and slow response). The two 500’s mellowed this out to about 4 DB. With the Outlaw in the mix, I am only getting a 2 DB swing. Not sure what significance this is yet as I haven’t had time to watch / listen yet.

I also spent some time messing around with the center channel. I added the VP150 above the screen. I played around a bit by disconnecting the M22’s and listening to just the VP, then swapped to the VP. Sonically, neither one really jumped out at me as significantly different in sound. They both sound just dandy to me. I spent a couple hours with the Dave Mathews BR disk and DD HD. One thing that bothered me some with running the M22’s as a center was I always knew that vocals and center imaging was coming from below the screen. My eyes would tend to drift to them. When I tried the VP on its own, same thing happened, but this time up – obviously. With both the VP and the M22’s firing, all is golden. Even when I sit to one side of the room, the center or the other side, the center channel is right where it needs to be, on the screen. I like this arrangement. I’m going to keep it as is. I had thought that I’d end up ditching the M22’s for another VP 150, but I have absolutely no desire to do this.

I have some more playing to do, but for now, this room has never sounded better.



The Outlaw hiding.....

I still like that room. I'm glad the VP150 worked out for you. I only get the sense that the dialogue is coming from below the screen when I think about it. When I'm involved in what's playing it never really occurs to me. But I'd still like to experiment with another M22 above the screen at some point. I won't have the space for dual vertical centers in the above/below configuration when I move my system and get a projector, but I'm still kind of curious. I will be jealous of people with high enough ceilings to allow for a large projected image and centers above and below.

Did you say anything about trying a single M22 below the screen instead of keeping both? I can't remember if you mentioned experimenting with that.

Very good, Mike; enjoy.

I bet that room sounds awesome. Sometimes I wish my HT was not part of a bigger recroom. Maybe it is time for some re-construction to isolate my HT.

Randy, your room is already way too nice. Stop making me more jealous.