I've been looking to upgrade an old (c. 1985) stereo Beosystem 5500-based system driving a pair of Bohlender-Graebener Radia 520s via a Carver TFM-22 amp and a custom-built 96l 12" sealed sub (Q around 0.6) to include 5.1 or 7.1 surround. The primary display device is a Sony 32" HDTV. (A pair of Carver Silver speakers requiring repairs to the ribbons sits in storage, as well).

So, naturally, I find Outlaw's offerings interesting.

I particularly liked the idea of retaining a good stereo amp for the L+R mains, and using M200 monoblocks for the other speakers (considering 2 or 4 Radia 420s and a Radia 220 center). Of course, then the question of speaker-level signals to the speakers or line-level signals to amps near the speakers comes up. And, if considering the latter, should I use balanced signal transmission? Soundhound's criticisms of balanced circuits throughout noted, I wonder if balanced input and output stages for a run of 65' (wiring distance to farthest speaker in a 25x16 room) are justified. 65 feet is starting to get up there, in terms if length.

Soundhound made it sound as if the preponderance of odd harmonic distortions in balanced designs, even when confined to I/O stages, render any such design not worth considering. If that were the case, then the noise-immunity afforded by using balanced lines on long component interconnects would be for naught, if only to have to suffer odd harmonic distortion. Clearly, it must be possible to manage such distortion in managed systems. The question is, then, does the 990 do it well enough on it's balanced interfaces?

Bluntly, is anyone actually using, or planning to use, the balanced outputs on a 990, or have reason to believe that Soundhound blew a legitimate issue out of the realm of audability when it comes to a $1000 component (IOW, if it mattered that much, the 990 wouldn't even be a contender.)

RSH, this is a sensitive issue for some (but not for me!)

I will take balanced over unbalanced anytime. Check out this article that explains the difference:

http://www.audioholics.com/techtips/audioprinciples/interconnects/Balancedvsunbalanced.php

I have Carver Tripath digital amps with balanced inputs and whatever I wind up with - Outlaw or Anthem - I will be using balanced interconnects. Why do so many high end manufacturers like Bryston and Theta, just to name a few, make such a big deal of it? There's got to be a reason and the article I posted the link to explains it fairly well.

BTW, I am an engineer working for Honeywell so I am not really trying to blow smoke up anyone's butt

I also plan on using the balanced out's for the sub (it has a balanced input option & for the LCR where I am using electronic crossovers with balanced in. My main reason is to cut down the ground hum a bit. I've had to twiddle power more than I like to remove hum and still have a little if I put my ear to the speaker. I'm hoping balanced will remove this last bit.

stabie, I am jealous! My SVS sub does not have an XLR input. I guess I am going to have to live with it.

I plan to use the balanced subwoofer output of the 990 for the unbalanced input of a sub (intend on buying the LFM-1 along with the 990). The reason is because the route to the sub location involves going up a wall through the attic and down another wall (my house is on a slab, ugh!). This will be 50+ feet. I'll use an XLR to RCA transformer to go from balanced to unbalanced for the last few feet. Hopefully, this will allow me to benefit from the added noise cancelling properties of using the balanced output.

This is assuming that both the balanced and unbalanced outputs are active simultaneously.

I will be using the Balanced output because I am looking at connecting the 990 to a FBD on the way to the sub amp. Which a lot of people use to deal with room modes, ie rattling heat ducts..

http://www.behringer.com/DSP1124P/index.cfm?lang=ENG

barnabas-My velodyne hgs-18 would make you very jealous. It rattles the room without even trying.

trikos, do you have a balanced input on the sub or are you going XLR - RCA to the sub? I have heard good things about the Behringer but don't have a lot of practical knowledge. I'll download the manual. Does it essentially do room EQ for the sub?

barnabas: I am well aware of the advantages of balanced interconnections and their ability to fight inductively and capacitively coupled interferance.

Such interconnections are usually not used on consumer gear because (a) interconnections are short (though 5.1 setups are making that less true), (b) they add expense. Nevertheless, their value in combating interferance is well known.

That said, soundhound's observations regarding a relative increase of odd order harmonic distortion bears investigating: if the benefits of balanced drive are not there (because of a short run), and there are greater relative disadvantages because of the nature of balanced output stages, it might not be worth it.

As for running a balanced output to an unbalanced input (via simple XLR to RCA), you may be defeating the purpose, as the termination could unbalance the circuit (depending on the output stage topology). Furthermore, IIRC, balanced signals are referenced to a higher level than unbalanced ones, so you might need some attenuation (this may be built into some XLR to RCA adapters).

I hadn't considered the value of a balanced run to a sub amp: induced 60 Hz rejection, though that makes some sense. My sub, using a Hypex HS200 amp, does not offer balanced inputs :-( I have found that a 30 foot run of decent interconnect cable connected to signal (and chassis) ground at both ends carrying a single-ended sugnal to my sub amp does not pick up audable 60 Hz interferance, though. I did have a ground loop problem at one point, but running the three grounded power cord from the sub amp through a GFCI, and lifting the ground from the GFCI worked. (This is much safer than simply lifting the safety ground as any current inbalance caused by a ground fault (i.e. through a body) will trip the GFCI.)

Given runs of up to 65 feet, I am definately biased in favour of running line level signals to amps located near speakers, rather than speaker level signals and dealing with resistive losses: the BG speakers present nominal 4 ohm loads. If I have to run line-level signals that long, I'd prefer driving a balanced line.

So, the question remains: how bad is the odd order harmonic distortion from the balanced output of the 990? Is it as bad as soundhound suggests? I am not entirely convinced that (a) it is significantly worse than the unbalanced output and (b) the reduction of even order harmonic distortion from balanced output stages somehow masks what is present less.

I don't deny that the odd harmonic distortion from a balanced output stage might be worse than from an unbalanced one. The questions are "Is it noticible?" in the context of the rest of the signal quality produced by a $1k component, and "Is it the lesser evil when considering a 65 foot signal run?"

As I already have a decent stereo amp for the L+R mains (though I am considering upgrading to a better one, with balanced as well as unbalanced inputs), and the run from the 990 to that amp and speakers is the shortest of all, it isn't an issue for the most critical speakers when listening to two channel music. So, some minimal inaudable distortion to the surround speakers might be tolerable, even if the signal is theoretically "worse" by some measure.

I suspect however, that the benefits offered by a better physical connector usually used for balanced interconnects over an RCA phono plug probably exceed any increased odd harmonic distortion.

BTW, I hear that someone is offering to mod M200s for balanced operation. Does anyone know if that's correct, and at what cost?

Barnabas:

I have one sub now which is based on Infinite Baffle design vented behind the screen. It is connects directly to a Behringer 1400 watt amp in bridged mono mode, which does have Balanced inputs on the amp. So with a 990 I would have Balance from the 990 --> FBD --> AMP.

See: http://www.behringer.com/EP1500/index.cfm?lang=ENG These run about $300 a unit and since I use rack mounting they are ideal.

I am thinking of adding an LFM1 if I get a 990 to the second LFE output and using the FBD to handle both.

The FDB is an awesome unit. It allows you to flatten your sub response for your room and also "notch out" frequencies that are problem areas, like windows, heat ducts, or areas that are boomy because of room modes. They sell for $99 online, which is way too cheap for a unit like this.

We don't all have a anechoic chamber in our houses..

You will need to setup a PC with a mic to measure your frequency response. Since I build my own speakers, I already had that stuff.

A really good reference site for FBD and Infinite Baffle subs can be found at: http://f20.parsimony.net/forum36475/index.htm