R4, R44 question

**fbov** · 14 February 2011, 18:22 Monday

Actually, I see no reason not to use a Statement center.

Dual center channel speakers on either side of the screen are a very bad idea. Anytime two speakers produce the same program, you get wave interference; no sound when path length is 1/2 wavelength different, double sound when path length is integer wavelength difference. This is called "lobing." The wider the separation (as a function of wavelength), the greater the variation in FR in the listening area.

To get a uniform FR in the listening area, dual drivers must be <1 wavelegth apart. Statement CC woofers are 14" apart, but cross at 330Hz, when the wavelength is still >40", and the TM portion is aligned vertically, so there are no horizontal issue. He even tweaked the TM XO so the acoustic axis tilts up, as one might want for a below-screen placement.

Have fun,
Frank

**bigjohn** · 14 February 2011, 18:57 Monday

Thank you for your reply, i agree that a dual center is not ideal, however i forgot to mention one other factor, the center channel and its stand are currently blocking the fire place and in order for me to get the WAF to build the statements i need to move the center out of the way(something to do with actually wanting to use the fire place while watching a movie or some such ridiculous notion). the statement center needs 18" (i believe) behind it and there is no way for me to mount it above the screen or below and get the WAF. each speaker will have the drivers < wavelength apart with the only destructive interference coming from horizontal dispersion as the waves cross at distance from the screen.

**AdelaaR** · 14 February 2011, 18:59 Monday

nm .. figured it out

**Jed** · 14 February 2011, 19:03 Monday

Originally posted by bigjohn

Hi all,

This is my first post on this forum. attached is my current setup with B&W 683's as the mains and the HTM62 as the center(i apologize for the cable management, i realize it needs some work, as well as the power cable for the TV screen being way to short). i am planning to build a pair of Statements to replace the B&W's and as you can see there isn't a good place for the statement center. my original plan was to design a dual center based on the W4 and Neo 3.0 as used in the statements to flank the TV screen. then as i was going through the posts i found the R4 and R44 designs. and my question is; keeping the overall dimensions the same would it work if i changed the speaker placement from the front to the sides, as the shelf they are going to be placed on is only 7" deep. would this significantly affect the crossover design or over all sound quality of the speaker? my second question is which one R4 or the R44 would work best as a center channel, they will be powered by a B&K 200.5. any help or advice would be greatly appreciated. i was having issues uploading my pics as jpegs so printed them as pdf's and attached them.

-John

Between the R4 and R44 for a CC, I'd go with the R44 for the added power handling. It should work out fine, and I doubt the lobing will be that audible in a center channel application with such small diameter mids as used in the R44. The ideal solution is a 3 way with 1 mid or 2 mids tightly spaced together, if a ribbon is used because it generally requires a higher crossover point. Since it sounds like there are space issues, sometimes you have to make a few compromises.

Regarding your questions about the baffle, you'll want to keep it as close to the stock dimensions as possible. Adding more baffle on each end (more width) in a CC application won't effect the crossover design all that much though.

**Silver1omo** · 14 February 2011, 19:16 Monday

I would start by trying with no CC at all and see if that works for you. I currently have a 4.1 setup with no CC and it works for me.

**bigjohn** · 15 February 2011, 15:35 Tuesday

that you all for the responses and advice. i have tried a 4.1 before with my B&W's and it just seemed to be lacking, no matter how i messed with the speaker toe in, while watching movies it just never seemed to work right. i think i am going to go with the R44 design and start in on those in the next week or so, and i will post some pics when it is all done.

**fbov** · 15 February 2011, 19:14 Tuesday

Originally posted by bigjohn

...each speaker will have the drivers < wavelength apart with the only destructive interference coming from horizontal dispersion as the waves cross at distance from the screen.

Maybe I'm being unclear... "each speaker" tells me you're still planning to build 2 R44s, and place one on each side of the screen, where your L and R speakers actually belong, and feed it the CC signal....

This is the really, really, baddest, awfullest, bad thing you can possibly do to screw up a CC application. Your L and R ears will hear different frequency response, no matter where you put your head.

Anyone else pick up on this... anyone think it's a good idea?

If nothing else, you'll have a nice pair of surrounds when you're done.

Have fun,
Frank

**Jed** · 15 February 2011, 21:09 Tuesday

Maybe by the word "speaker" he means "driver"? I don't recommend building the R44 with a different driver layout spacing, in any case.

Jed

**bigjohn** · 15 February 2011, 21:18 Tuesday

Originally posted by fbov

Maybe I'm being unclear... "each speaker" tells me you're still planning to build 2 R44s, and place one on each side of the screen, where your L and R speakers actually belong, and feed it the CC signal....

This is the really, really, baddest, awfullest, bad thing you can possibly do to screw up a CC application. Your L and R ears will hear different frequency response, no matter where you put your head.

Anyone else pick up on this... anyone think it's a good idea?

If nothing else, you'll have a nice pair of surrounds when you're done.

Have fun,
Frank

As an Experiment today i stopped by Radioshack and got a $5 RCA splitter then i hooked up 2 B&W 685's as a dual center and watched 20 minutes of Starship Troopers and switched back to my single center and re-watched the same portion of it. and to be honest i couldn't tell the difference between the two setups, i agree that in an ideal setup with measuring equipment and such, there would be a discernible difference but to my imperfect ears i cant tell the difference

**fbov** · 15 February 2011, 22:56 Tuesday

That was me a few years ago. My first CC was the L/R speakers built into the TV, after a few years using 4.0.

One downside of the hobby is that the more I listen, the more I can hear. I recently upgraded my CC from a high-quality MTM, albeit turned sideways, to a "proper" MTM CC and the improvement in dialog clarity was amazing. Another poster (lunchmoney) worked with Zaph to create a new sideways MT CC, replacing a sideways MTM with similar subjective results.

That said, I see your problem... nothing really good fits where you need it if the fireplace is to work. I'm in a similar room, but with the fireplace to my right so I have other issues.

Sorry for yelling... I just wanted you to go into this with your eyes/ears open.

Have fun,
Frank

**Jed** · 15 February 2011, 23:50 Tuesday

I'm a bit confused, but if you want to use a pair of R44s wired in parallel that's a no go in my book. The impedance will be something like 2ohms.

**bigjohn** · 16 February 2011, 12:15 Wednesday

Originally posted by fbov

That was me a few years ago. My first CC was the L/R speakers built into the TV, after a few years using 4.0.

One downside of the hobby is that the more I listen, the more I can hear. I recently upgraded my CC from a high-quality MTM, albeit turned sideways, to a "proper" MTM CC and the improvement in dialog clarity was amazing. Another poster (lunchmoney) worked with Zaph to create a new sideways MT CC, replacing a sideways MTM with similar subjective results.

That said, I see your problem... nothing really good fits where you need it if the fireplace is to work. I'm in a similar room, but with the fireplace to my right so I have other issues.

Sorry for yelling... I just wanted you to go into this with your eyes/ears open.

Have fun,
Frank

i appreciate the advice, and i do realize that it is not that ideal of a setup, i recently bought the house and I've wished the the owners before me hadn't put that fire place in, as it isn't original to the house. but given the limitations of the room and trying to balance the best possible sound within the constraints of the room and WAF I think it is a good start. In truth the dual center most likely wont last more than a year or two as i enjoy tinkering and changing things too much, I just need to start somewhere.

Originally posted by Jed

I'm a bit confused, but if you want to use a pair of R44s wired in parallel that's a no go in my book. The impedance will be something like 2ohms.

the idea would be to split the RCA signal from the preamp to 2 channels of a 5 channel amplifier then run a speaker from each channel, there by not letting the amplifier see a load lower then 4ohms.

**fbov** · 17 February 2011, 12:01 Thursday

I like your approach... start somewhere, and go from there.

I also deal with WAF, and find positive comments very rare. Upgrading the CC got me one....

Have fun,
Frank

R4, R44 question

R4, R44 question

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