question: 2641, LCR, front-end matching

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HeatMiser

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question: 2641, LCR, front-end matching
« on: 13 Mar 2006, 08:17 pm »
Greetings all, long-time lurker/first-time poster here.

Been following the development of the 2641 for a long time now, but I've been planning a cross-country move for some time so I've had to hold off from starting any large projects.  My tentative plan is a 5.1 HT setup, 2641 - LCR - 2641 and a pair of 641s in the rear.  I won't even think about a sub until I see what the room is going to be like.

This all seems straightforward enough, and the speakers get uniformly rave reviews, but questions raised in http://www.audiocircle.com/index.php?topic=25272&start=35">this thread have me wondering about a few things.

The 2641 and the LCR have very different crossovers, even so far as having even-order vs odd-order alignments in places, and it seems to my admittedly untrained mind that this is bound to create issues with the theoretical ideal of a "matched front end" that you want to end up with in a quality HT setup.  If you hook up the LCR so that the woofers are operating in phase with those of the 2641, you get a relative phase reversal between the LCR and the 2641 at some point.  Now I have no idea how much of a problem (if any at all) this really creates in practice, but it sure seems different from the "on paper" ideal of, say, 3 identical LCRs, or a pair of 2641s and a (non-existent) "2641 center" done more to Kevin's preferences, specifically to match the existing 2641 design.

So, questions:

- Does this not matter at all in practice?  Why not?
- Anybody here living with a 2641 - LCR- 2641 front end who cares to comment?
- Any plans for a re-invented center channel done more specifically to match the 2641?

Sorry this got so long, thanks for reading and thanks in advance for any comments.

Kevin Haskins

Re: question: 2641, LCR, front-end matching
« Reply #1 on: 13 Mar 2006, 09:22 pm »
Quote from: HeatMiser
Greetings all, long-time lurker/first-time poster here.

So, questions:

- Does this not matter at all in practice? Why not?
...


It is a rather complex subject.   To simplify the subject phase matters when it affects frequency response.    This happens when you get either constructive or destructive interference with other waves.    With a single loudspeaker one of the primary goals is smooth frequency response.    To get it you use crossovers that keep the drivers from producing frequencies that overlap and cancel.    

That is all fine and dandy but when you place a loudspeaker in a room you get all kinds of cancelizations, nulls and peaks from reflected energy.   It is a chaotic situation.  ;-)

Between two loudspeakers if you have them out of phase you will most likely (most likely because the room & the speaker posn within the room have a huge influence) get more bass cancellation issues.    

The issue from the other thread was a customer worried about bass cancellation between the LCR & the 2641.   We designed the two at different times and I had the networks arranged so that they would cancel.    I simply changed the documentation to change the polarity, problem solved.  

In terms of matching speakers there really is no perfectly matched loudspeaker.   The room prevents this....   The 2641 & the LCR are so close from the standpoint of where they are crossed over, drivers used and polar pattern that I wouldn't get too excited about it.   Choose the loudspeaker that fits your application.    

In terms of the crossovers being different.... well the electrical response isn't what we focus on.   We focus on the total acoustical response, which is a function of the electrical plus acoustical response.   The final response and polar pattern are the critical things to match, not some arbitrary component count.   The actual electrical network used is important in my opinion only in how it affects the final acoustical output and the impedance it presents to the loudspeaker.

HeatMiser

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question: 2641, LCR, front-end matching
« Reply #2 on: 13 Mar 2006, 10:53 pm »
Thanks for taking the time to explain all that Kevin.  If I understand correctly, it sounds like part of what you're saying is that in the chaotic mess created by the whole room+ multiple speakers system the kind of subtle specifics I was asking about are not a concern.  Fair enough.

I certainly am looking forward to tackling this project once I get settled.  Hopefully I'll be able to contribute some nice pics and yet another great review in a few months. :D

Al Garay

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question: 2641, LCR, front-end matching
« Reply #3 on: 14 Mar 2006, 09:03 pm »
If you have the space and budget, go for the LCRs in the rear. In my opinion, they will be a better match than the Kit641 especially when listening to 5.1 concerts.

dawaro

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question: 2641, LCR, front-end matching
« Reply #4 on: 14 Mar 2006, 10:15 pm »
Well I have had mine set up for a couple of days. 2641's for the mains, LCR for the center and 61's for the rear.

As far as music or concert DVDs So far I have listened to The Eagles Hell Freezes Over, Kiss Symphony, Inxs Just Looking and AC/DC Family Jewels.

I have not had any apparent phase issues with any of the speakers. While building the LCR I changed the phase for the drivers at the xover per Kevin to match the LCR. This was based on the original instructions that are being revised. To check the phase I used a 2641 for the left channel and the LCR for the right and listened to a stereo signal. I did the same with the 61's also just to make sure there were no phase issues. I also ran the Avia HT set up DVD through to double check everything.

I have only had the time to sit and watch one movie so far, a pre-release of King Kong on loan from the local video store. Very impressive. The dialog is spot on. As for the low response, I made it half way through the movie before I realized the sub was off...

HeatMiser

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question: 2641, LCR, front-end matching
« Reply #5 on: 15 Mar 2006, 12:56 am »
Al, thanks for the suggestion.  I think I'm going to have to sacrifice large, truly full-range surrounds in the name of WAF and probable lack of space as well.  I have a feeling I'll be happy enough considering the tremendously huge upgrade this all represents compared to my current setup.  :D

dawaro, thanks for sharing your experience, and the comments posted on your behalf in the other thread were welcome too.  I think I share your preference for designs with more elegant, less abrupt crossover solutions and Kevin certainly seems to have come through for us.

I guess all this was just me overthinking things I don't have the background or experience to fully understand.  I can't wait to get started now.