Build Thread: SR71-inspired Center Channel

[lunchmoney]

Re: Build Thread: SR71-inspired Center Channel

I used the in-wall, no BSC design in a similar application because the BSC design is boomy.

It is? Are we talking about SR71's here?

The original SR71 BSC design I found to be a tad too warm and heavy in the midrange, but IMO "boomy" is not accurate.

This was with the speakers on stands, with nothing around them to act as baffle.

A very slight decrease in BSC (reducing woofer inductor from 3.3 mh to 3.0 mh) was all that was required to solve the slightly heavy midrange.

To my ears, anyways, and of course other aspects of the setup (the room, the components, the source, etc) could have a big impact here.

"boomy" is light years away from how I would have described the original bsc.

[fbov]

Re: Build Thread: SR71-inspired Center Channel

You're right about what defines the baffle width, but only in clear space.

The furniture, floor and TV - all surfaces near the speaker - become part of the baffle, and thus the LF response. There are big waveform interactions with other nearby objects, but not at low frequencies; the complication is not resolved by long wavelengths.

The complication, if you measure FR, is to resolve room/placement effects independently of the speaker design. Fortunately, BSC is a broad-band effect, superimposed on the room modes and surface bounces peculiar to your relative speaker-room interaction. In my case, I'm sensitive to overall tonal balance, so my ears knew about the problem long before I understood BSC.

Have fun,
Frank

[jim85iroc]

Re: Build Thread: SR71-inspired Center Channel

Jim,
BSC requirement is defined by baffle width, but you're primarily interested in the upper bass and midrange wavelengths, so it's small changes from the design width that would define an intermediate BSC. A 5' wide entertainment center would just hold a moderate size flat panel, and affect frequencies below ~100Hz, which is just about sub territory.

I used the in-wall, no BSC design in a similar application because the BSC design is boomy.

HAve fun,
Frank

I'm assuming "Baffle width" to be defined as the width being the shortest dimension regardless of whether it's in the horizontal or vertical plane. Sure, the cabinet might be 6' wide, but the drivers are only a matter of inches away from the top of the cabinet, which then of course holds a 50" tv which is set back a foot. To me, that becomes a much more complicated baffle step issue than an imaginary speaker box that's 6' wide... but maybe I'm over complicating things. I intend to measure this, but because the setup sits so close to the floor, I'm not sure how meaningful my low frequency measurements can be.

[fbov]

Re: Build Thread: SR71-inspired Center Channel

Jim,
BSC requirement is defined by baffle width, but you're primarily interested in the upper bass and midrange wavelengths, so it's small changes from the design width that would define an intermediate BSC. A 5' wide entertainment center would just hold a moderate size flat panel, and affect frequencies below ~100Hz, which is just about sub territory.

I used the in-wall, no BSC design in a similar application because the BSC design is boomy.

HAve fun,
Frank

[jim85iroc]

Re: Build Thread: SR71-inspired Center Channel

Lunch,
finding this thread couldn't have come at a better time. I'm in the process of designing/building a center channel, and my entertainment system is very similar in size to yours, and like yours, my center speaker is designed to fill the space within the cabinet. Do you have any information on what the modeled baffle step wound up looking like? I'm a bit unsure of how to model the baffle step... do I just use the dimensions of the entertainment center, or do I work the dimensions of the TV into the mix as well? Once I get my soundeasy in, I hope to do some measurements, but I'm hoping that you've got some info that I can use as a reality check for when I do take my measurements.

Thanks

[benchtester]

Re: Build Thread: SR71-inspired Center Channel

.... and John K doesn't take requests :-).

........

Just to avoid confusion: Zaph => John Krutke => jkrutke (user name here)

john k => John Kreskovsky => johnk... (user name here)

But wait, there's more (Johns) .... on second thought ... never mind. :D

[lunchmoney]

Re: Build Thread: SR71-inspired Center Channel

Lunch;

Very nice work!

I just complete phase 1 of another Zaph design, the ZRT 2-way ported project. My phase 2 involves evaluating some of the tweaks John recommended and maybe actually painting the boxes. I also built an easy to mod box (interior volume and driver placement identical to the design). Among other things, I can easily move the port from front to rear.

I now have a big problem but am encouraged by what you have accomplished. My new ZRTs really delivered, even on the first audition. My wife suggested they had kept me company in my shop for long enough so I finally dragged them upstairs to share with the family. I really built them for music but, like your arrangement, they are now also part of our home theater array. A few years back, I built a Tony Gee USB with a few cabinet mods to make it able to support the television. It was more than satisfactory until flanked by the ZRTs. I can't say there is anything wrong with Seas T18 based USB but they do make me wonder how a similarly voiced Scanspeak Revelator based center channel would sound. I'm not too worried about working with the box geometry but the crossover is way above my pay grade and John K doesn't take requests :-).

I am wondering if anyone has already tackled this problem.

M

BTW-symmetry is over rated.

Contact Zaph, and see what he would think about making a SRT-inspired center channel.

He was very helpful with my center, and gave me a good shove in the right direction. I then tweaked from there, and it is simply stunning.

[MMeche]

Re: Build Thread: SR71-inspired Center Channel

Lunch;

Very nice work!

I just complete phase 1 of another Zaph design, the ZRT 2-way ported project. My phase 2 involves evaluating some of the tweaks John recommended and maybe actually painting the boxes. I also built an easy to mod box (interior volume and driver placement identical to the design). Among other things, I can easily move the port from front to rear.

I now have a big problem but am encouraged by what you have accomplished. My new ZRTs really delivered, even on the first audition. My wife suggested they had kept me company in my shop for long enough so I finally dragged them upstairs to share with the family. I really built them for music but, like your arrangement, they are now also part of our home theater array. A few years back, I built a Tony Gee USB with a few cabinet mods to make it able to support the television. It was more than satisfactory until flanked by the ZRTs. I can't say there is anything wrong with Seas T18 based USB but they do make me wonder how a similarly voiced Scanspeak Revelator based center channel would sound. I'm not too worried about working with the box geometry but the crossover is way above my pay grade and John K doesn't take requests :-).

I am wondering if anyone has already tackled this problem.

M

BTW-symmetry is over rated.

[Theresa]

Re: Build Thread: SR71-inspired Center Channel

Ha!

Yeah, I can't help wondering how many center channels out there have less than optimal performance because of a pointless requirement that they be visually symmetrical.

If all goes well, this should perform better than many MTM center channels, despite the asymmetrical layout.

I concur. The demands of aesthetics that such things need to be symmetrical makes for bad sound, at least outside the very narrow sweet spot. Form should follow function. If I had a rack that would take my center lying on its side I would do so. As it is, mine is hanging from the wall above and behind the tv's screen. It sounds fine up there, I do not localize it as different from the mains. I can, and have, tweaked its delay to better blend. It is up against the wall so it doesn't need any baffle step compensation and neither should yours since its flush to the cabinet. Good taste in drivers by the way. SEAS is second in my own mind only to ScanSpeak and then only with their most expensive drivers. I seriously considered the SR71 and I still think it looks like a very good speaker.

[lunchmoney]

Re: Build Thread: SR71-inspired Center Channel

So after more than a week of listening, here are my impressions....

I am VERY pleased. Thrilled ya might say.

It's a perfect match for the SR71's. If you've heard how good SR71's are, you could stop right here. Enough said.

Vocals are very detailed, without being harsh or fatiguing. They are high-passed, so I can't comment much on bass response, but mid-bass is very full and satisfying. One thing I've always liked about SR71's are their super smooth, non-fatiguing sound, and the Blackbird follows suit.

Compared to the Tritrix center channel I was using before? No comparison. Much more detailed and clean sounding, much fuller mid-bass, much less fatiguing. Better in every way. That's saying a lot, since I have much love for the Tritrix.

This cost me about $200 to build, soup to nuts. Clearly this would absolutely lay waste to a store-bought speaker anywhere near that price. You might be pushing 1k to do better, seriously.

Overall, an SR71 + Blackbird front stage is simply awesome. Not a really huge, BIG speaker sound, but amazingly clean and detailed due to awfully nice SEAS drivers. Add a sub, and it's just amazing. I'm currently using a modest Dayton Ref 10" in a 1 cu ft sealed enclosure, and I'm more than happy.

Thanks for tuning in, and it is my sincere hope that others may use this info to build their own!

Cheers!

Dan

[lunchmoney]

Re: Build Thread: SR71-inspired Center Channel

Here's a dimensioned drawing of the final design

[greywarden]

Re: Build Thread: SR71-inspired Center Channel

As discussed earlier in this thread...

There was simply no need to. The shelf has big gaps in the back for running cables, etc.

Also, why risk midrange leaking out of the front of the speaker?

And finally, didn't like it aesthetically.

Originally I wanted to just make the cabinet sealed, since it's high-passed anyways, but Zaph pointed out the midbass performace could really suffer... the woofer is really designed for ported enclosures.

Hmmm... Maybe I should rear-port my 2ways?

[Brewski]

Re: Build Thread: SR71-inspired Center Channel

Congrats on the build lunch Glad to hear that it turned out well.

Take it easy
Jay

[lunchmoney]

Re: Build Thread: SR71-inspired Center Channel

Why didn't you port this out the front?

As discussed earlier in this thread...

There was simply no need to. The shelf has big gaps in the back for running cables, etc.

Also, why risk midrange leaking out of the front of the speaker?

And finally, didn't like it aesthetically.

Originally I wanted to just make the cabinet sealed, since it's high-passed anyways, but Zaph pointed out the midbass performace could really suffer... the woofer is really designed for ported enclosures.

[john trials]

Re: Build Thread: SR71-inspired Center Channel

Why didn't you port this out the front?