Dual L and R Channel Question

[sapo916]

I run a Yamaha HTR-5840 Receiver for my 5.1 system, http://www.yamaha.com/yec/products/productdetail.html?CNTID=200021

I run 2 Athena AS-B1 speakers for L R channel and along with the matching center speaker. I run 2 Boston Acoustics HD8 speakers for surrounds.
http://www.soundstage.com/revequip/athena_asb1.htm

Now my curiosity is this, I actually have 5 AS-B1 speakers and since my receiver has A and B speaker outputs I was wondering if I could gain any advantage by running 2 AS-B1 speakers for the L and R channel?

Thank You, this is a curiosity question because I am in the progress of upgrading my whole system piece by piece.

 

[TLS Guy]

I run a Yamaha HTR-5840 Receiver for my 5.1 system, http://www.yamaha.com/yec/products/productdetail.html?CNTID=200021

I run 2 Athena AS-B1 speakers for L R channel and along with the matching center speaker. I run 2 Boston Acoustics HD8 speakers for surrounds.
http://www.soundstage.com/revequip/athena_asb1.htm

Now my curiosity is this, I actually have 5 AS-B1 speakers and since my receiver has A and B speaker outputs I was wondering if I could gain any advantage by running 2 AS-B1 speakers for the L and R channel?

Thank You, this is a curiosity question because I am in the progress of upgrading my whole system piece by piece.

No that will be worse and dangerous for your receiver. Two speakers side by side will interfere with each other by a phenomenon known as comb filtering. Two speakers will almost certainly drop the speaker impedance to around two ohms on the lower frequencies stress and probably damage your receiver.

Bottom line: -put the idea out of your head.

 

[JerryLove]

No that will be worse and dangerous for your receiver. Two speakers side by side will interfere with each other by a phenomenon known as comb filtering. Two speakers will almost certainly drop the speaker impedance to around two ohms on the lower frequencies stress and probably damage your receiver.

He's talking about running one set through "Speaker A" L and R connectors and the other set through "Speaker B" L and R connectors.

I don't think the ohm-drop problem occurs in that case. If it did, it would be insane that almost every AVR manufacturers even let you choose "A+B". I believe you are thinking of hooking up the speakers in parallel to a single pair of outputs.

But please correct me if my understanding is in error there.

As to comb filtering: how is that avoided in speakers with more than one identical driver? Or when running multi-channel stereo (with the R-L signals duplicated to surrounds), or in clubs, or from running a mono source (say, the new Beatles remasters) through two speakers?

 

[TLS Guy]

He's talking about running one set through "Speaker A" L and R connectors and the other set through "Speaker B" L and R connectors.

I don't think the ohm-drop problem occurs in that case. If it did, it would be insane that almost every AVR manufacturers even let you choose "A+B". I believe you are thinking of hooking up the speakers in parallel to a single pair of outputs.

But please correct me if my understanding is in error there.

As to comb filtering: how is that avoided in speakers with more than one identical driver? Or when running multi-channel stereo (with the R-L signals duplicated to surrounds), or in clubs, or from running a mono source (say, the new Beatles remasters) through two speakers?

You are unfortunately in error, and it leads to a lot of grief. The speaker A & B switches are simple switches. They do not have separate amplifiers. If you select A & B at the same time, the speakers are in parallel.

As to comb filtering it occurs in all the conditions you describe. It is the Achilles heel of the line array.

In the D'Appolito MTM configuration, this effect is something that has to be taken into account when selecting the crossover point and driver spacing.

In the more common 2.5 way only the top identical driver hands over to the tweeter. The lower one shelves in below 600 Hz for diffraction compensation, and the wave lengths involved are larger than the driver spacing.

If you see speaker with two tweeter, two midranges side by side etc, walk the other way.

This problem of comb filtering is an issue with crossover design however, and is to a degree unsolvable in analog crossover design. The lower the order of the filter, the better the phase and transient response. Time delay is also less. However driver overlap and therefore comb filtering is a problem.

A fourth order filter while minimizing overlap, although it still exists as there is still significant power until an octave either side of crossover, they make a square wave look like a sign wave. Also all the inductors in circuit have a deleterious effect on amplifier performance.

Zero phase digital filters show the most promise for helping with these issues. That will require a shift in practice to active speakers in a big way.

The full ranger community is not nuts. They are avoiding real problems, but also have problems of their own. We all should be, and I remain a full ranger at heart. That is I think the best corner to come from with speaker design.

 

[JerryLove]

TLS Guy,

Thanks. I remain surprised that both dual outputs (A and B) and the ability to set both to "active" simultaneously is so ubiquitous given the significant danger to equipment you describe.

If running two pairs is in-demand, I would have expected manufacturers to (generally) do it safely, and if it's not in demand to (mostly) drop it from the products. This sounds like a problem that needs more press.

Dual (or more) driver designs are extremely common, from the EMP towers that have gained so much press here lately to Paradigm's large towers (like S8s or Studio 100s), to McIntosh (and IDP), to Infinity (their famous RS I and II come to mind). I'm curious if you perceive a similar problem with planars, as the sound is coming from a large plane (will the top of the emitter interfere with the bottom)?

Is this more of a problem with higher frequencies, or are these multi-woofer units (say the Paradigm sub recently reviewed by Audioholics) equally having to deal with comb issues?

 

[TLS Guy]

TLS Guy,

Thanks. I remain surprised that both dual outputs (A and B) and the ability to set both to "active" simultaneously is so ubiquitous given the significant danger to equipment you describe.

If running two pairs is in-demand, I would have expected manufacturers to (generally) do it safely, and if it's not in demand to (mostly) drop it from the products. This sounds like a problem that needs more press.

Dual (or more) driver designs are extremely common, from the EMP towers that have gained so much press here lately to Paradigm's large towers (like S8s or Studio 100s), to McIntosh (and IDP), to Infinity (their famous RS I and II come to mind). I'm curious if you perceive a similar problem with planars, as the sound is coming from a large plane (will the top of the emitter interfere with the bottom)?

Is this more of a problem with higher frequencies, or are these multi-woofer units (say the Paradigm sub recently reviewed by Audioholics) equally having to deal with comb issues?

A planar speaker is an entirely different situation. In most the membrane moves as one. The result is they beam like crazy, and have a n arrow sweet spot. The Quad ESL 63 uses delay electrodes built into the speaker, so the wave form is spherical. This is a unique approach.

With individual driver the issue is a function of wavelength. Wave length equals speed of sound divided by frequency. When driver are a wave length apart the frequency output has a peak, when a half wave length apart a null.
This also occurs for even multiples of the wavelength. That is why it is called comb filtering and it is a one of the big challenges of speaker design and one of the many reasons for speakers remaining the very weak link in the audio chain. The effect also varies according to listener position in the room, this lobing effect is worse with odd order filters.

Unfortunately there are many unsolvable problems to speaker design. Good speakers are the sum of intelligent compromise.

As mentioned in another thread, a big improvement could come about with technology we largely have.

1). Active speakers with zero phase digital crossovers.

2). The development of much wider band drivers, so that no crossover of any type has to be put in the speech discrimination band. There are drivers out there that fulfill this, but they are far and few between. The mid in the B & W 800 series is such a driver, but kept proprietary by B & W unfortunately. The best bet is probably a driver by ATC, but it is expensive, and because of its response, and active solution pretty much mandatory.

 

[JerryLove]

2). The development of much wider band drivers, so that no crossover of any type has to be put in the speech discrimination band. There are drivers out there that fulfill this, but they are far and few between. The mid in the B & W 800 series is such a driver, but kept proprietary by B & W unfortunately. The best bet is probably a driver by ATC, but it is expensive, and because of its response, and active solution pretty much mandatory.

You've just increased even more my desire to get my hands on an 800 series B&W.

For music, my favorite sounds have come from Maggies (sadly, I own none, and they can be difficult to position), but I've been really wanting to try some B&W 800s. The only shop nearby that I know carries them doesn't have them hooked up.

Many of the 800s use multiple woofers. I take that to be a trait in them you don't like?