AudioRoundTable.com: Pi Speakers » 1pi or 2pi for surrounds?

Home » Sponsored » Pi Speakers » 1pi or 2pi for surrounds?

Show: Today's Messages :: Navigator :: Polls
E-mail to friend

Re: 1pi or 2pi for surrounds? [message #69500 is a reply to message #69499]

Thu, 15 September 2011 12:35

Wayne Parham
Messages: 18785
Registered: January 2001

Illuminati (33rd Degree)

For home hifi and home theater, I like running the mains and surrounds full range because of the benefits in the modal region. Blending multiple sound sources smoothes the room modes.

If you were running in a prosound environment, it would be a different story. I wouldn't suggest running mains full range. In that application, you always high-pass the mains where systems are pushed hard, to limit excursion.

Or if you had little bitty mini-monitors using drivers that could easily be overdriven. In that case, you'd want to high-pass them too.

But this just isn't the case for speakers like these used in a home theater. These are efficient speakers designed for high-power use, and you have several of them. The mains carry most of the load, as do the subs. The surrounds don't really do all that much. Even in the occasional full pan to a surround channel, we're still not pushing these too hard. As long as you keep the power below 100 watts, they're fine.

On the other hand, if you have the capability to high-pass at the Helmholtz frequency, that would be a good thing to do. It will limit signals where the woofer is unloaded, and isn't making any sound anyway. But if it isn't possible, don't sweat it. These speakers handle a lot of power, and are efficient enough that they produce a lot of sound. You can easily get over 110dB/M from them, which is plenty for surrounds.

So with all that said, I do not suggest using high-pass - at least not above the Helmholtz frequency - with these speakers. Very little is gained in a home hifi or home theater environment. The benefits of reduced IMD (from high-pass) are far outweighed by the benefits of modal smoothing (by not using high-pass) in this application.

Report message to a moderator

Helmholtz frequency of each model [message #69505 is a reply to message #69500]

Fri, 16 September 2011 09:41

Wayne Parham
Messages: 18785
Registered: January 2001

Illuminati (33rd Degree)

It occurred to me that it might be helpful to list the Helmholtz frequency of each model here for reference. You can high-pass at this frequency to limit excursion where the driver is unloaded. There is very little sound produced below this frequency anyway.

one π loudspeaker - 60Hz
two π loudspeaker - 40Hz
three π loudspeaker - 30Hz
four π loudspeaker - 40Hz
six π loudspeaker - 30Hz
seven π loudspeaker - 40Hz
eight π loudspeaker - 30Hz
three π subwoofer - 20Hz

Again, for home hifi or home theater, I do not suggest high-passing the mains above this point. We want to blend the mains and the subs for modal smoothing. But there's no harm high-passing at the Helmholtz frequency because no sound is produced below that. These speakers have pretty stiff suspensions, so low frequencies aren't going to rattle them to death but high-pass at the Helmholtz frequency is a good idea anyway. Not required, but beneficial.

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69511 is a reply to message #68904]

Fri, 16 September 2011 18:16

smokarz
Messages: 56
Registered: June 2011
Location: CT - USA

Baron

thanks for posting that wayne.

it's interesting, because after i ran audyssey last night. it set the 1pis at 60hz crossover. exactly as you posted.

while setting my mains (horn/wg) at 90hz. i know my mains go flat down to around 50-60hz when i measured them.

not really sure if i can completely trust audyssey either.

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69512 is a reply to message #69511]

Fri, 16 September 2011 19:30

Wayne Parham
Messages: 18785
Registered: January 2001

Illuminati (33rd Degree)

Good to know the system chose a setting that made sense for the surrounds. I'd run the mains with high-pass at their Helmholtz frequency also, or just run them flat out. If you high-pass the mains, make it pretty low like 30Hz or 40Hz, wherever the Helmholtz frequency is.

The main thing is, we just don't want to rolloff the mains early. We want as many sound sources as possible playing in the room's modal region. Same thing for the surrounds, but with a different goal in mind. We're not looking to them for modal smoothing, since they play such different content. But we do need them to have similar spectral balance, and they need to be able to stand on their own, for the most part. They don't need to be capable of real deep bass - that's covered by the subs, which is non-localizable. But we do need them to run competently down to 60Hz or so.

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69516 is a reply to message #68904]

Sat, 17 September 2011 08:45

smokarz
Messages: 56
Registered: June 2011
Location: CT - USA

Baron

thanks wayne.

i like to give what you're saying a try. but i am not quite sure how to implement it with my current setup, without having to get additional devices.

here's my setup.

pre/pro: Integra 80.2
Amp: Emotiva UPA-7 (mains & surrounds)
Sub Amp: Behringer EP2500
Subs: 4x MFW-15 (in sealed boxes)

how would i run mains and surrounds as full (with an HPF such as 40hz for mains and 60hz for surrounds). and run subs with with a LPF such as 90hz.

and again, if i want to incorporate Audyssey, it has its own settings so that could get a bit complicated.

sorry, this is getting a bit off topic but this discussion is peaking my interests.

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69517 is a reply to message #69516]

Sat, 17 September 2011 09:00

Wayne Parham
Messages: 18785
Registered: January 2001

Illuminati (33rd Degree)

I'm not familiar with your components, so let me ask a few questions. Does the Integra have a way to select the fronts as "large" or otherwise choose to have them set full range, no high-pass at all? I think that's the only thing we want different from what it is trying to auto-configure. The surrounds are OK to high-pass at 60Hz, and the flanking subs are good for low-pass at 90Hz.

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69518 is a reply to message #68904]

Sat, 17 September 2011 09:16

smokarz
Messages: 56
Registered: June 2011
Location: CT - USA

Baron

yes it does. however, if i set it to full (large) then all contents of the main channels will go to the mains only, and not the subs. so the subs are not sharing the LFE contents of the mains, unless i cross it over to the subs, which mean having to set mains to small.

i believe that's how Audyssey works?

Report message to a moderator

Re: 1pi or 2pi for surrounds? [message #69522 is a reply to message #69518]

Sat, 17 September 2011 10:45

Wayne Parham
Messages: 18785
Registered: January 2001

Illuminati (33rd Degree)

You might consider getting one of these:

Active Sub Crossover

Seems cheesy, but it really works great. If you are running a separate sub amp anyway, then this isn't much extra cost at all. And doing the mods is kinda fun too.

Just set the mains as "large" and connect this crossover to a preamp out. For flanking subs, the 90Hz low-pass setting is usually best.

Report message to a moderator