paging Curt C and Dennis Murphy- rs 3way center

[jeffrey8128]

I may have done a poor job in searching through htguide threads and archives here, but I can't seem to find any real indepth performance impressions of the 3 way Dayton RS wmtw center.(2005 build)
Did any of the designs that you two worked on -i.e. different x-over schemes, work out as decently as you hoped and designed them to be?

I would particularly be interested in learning if you did any work on any internal box fine tuning parameters -i.e. bracing layout, and the amount of eggcrate foam and stuffing that works the best. Is it better to leave foam out of the M/T chamber?

Your input on this would be appreciated.
The "desire" to build a bigger 3way center has turned into a strong urge.

I googled and I liked what I read over at HTGuide about this center that went along with some nice big 3 way towers.

For the money and time to build, will I get a good bang for my buck(s)?

Thanks,
Jeffrey8128 (formally known as jeffrey)

[cjd]

There's a TON of information over at HTGuide including impressions from a whole lot of folks. I think it's pretty hard to beat for the cost, at least Dennis's variant which can be quite economical.

Most people have built Dennis's crossover, with a few doing Curt's. Brian Bunge built my variant to go with his larger 3-way towers I also did the XO for - I think he's the only one so far, as I've not done a "mains" variant, and the crossover cost is noticeably higher.

C

[dennismurphy]

Hi I think the reactions to both the center and L and R mains have been positive for both crossovers, although there isn't a lot of detailed information. I haven't had a chance to compare Curt's design with mine (at least not since Curt moved the tweeter crossover point up a little), but my best guess is that there is not a heck of a lot of difference. Both Curt and I used 2nd order slopes for the woofer-mid cross, and I think that's very important in a 3-way. It gives a sense of focus and coherence that 4th order slopes don't always provide. I regard this design as heavy duty. The center, along with the mains, can provide powerhouse performance at a reasonable cost. I don't think you'll want for power handling or impact. That said, it's pretty complicated and will make a lot of demands on your time. So I would make sure that you really value "big" and are willing to invest the necessary time. I haven't experimented with interior sound treatement. But I doubt that it would make a lot of difference.

[curt_c]

I have heard a couple of different enclosure variations of the mains version using Dennis's crossover, and found them both to sound excellent. I can't speak for mine, as my design was simply modeled using Dennis's provided response plots. I never built it, nor have I heard anyone’s version of it. I was designing my Exclamations! at the time, which uses similar drivers, and it seemed superfluous to build yet another enclosure.

The Dayton RS drivers are really high value for the dollar, and I suspect you will be satisfied with whatever iteration you choose. Voicing a three way is still something of a black art, and the on axis response tells you little of how the speaker will sound. Given that, and since I have no personal assessment of my own design, I’ll give my nod to those designs whose designers actually built and voiced them.

C

[dennismurphy]

I will certainly say Amen to your comment about on-axis response not being a reliable indicator of sound for a 3-way. I have one design now that uses a small 4" midrange, and it's still not right after over a month of experimentation. I have to assume that the problem arises from splicing in a driver with wide dispersion over a few octaves of pass band. It's very easy to end up with an awwwwwk coloration, particularly on brass. Fortunately, the RS design has very even off-axis response.

[jeffrey8128]

Thanks for the feedback.
I am actually assembling your 1800hz x-over version Curt for the 3 way rs center I am in the proccess of putting together.
I haven't cut any wood yet, and was just exploring for opinions on what has been proven out. I noted that there were a couple versions of enclosures that were designed/built - 16" deep, 12" deep. 1 had bracing perpendicular inline with woofers, another had bracing parallel.
I'm planning at this time to go with the deeper box.
Why am I asking about internal treatments for a center channel???
Well, I have been experimenting with different bracing and internal box treatments on a Cynosure 2.5.5 way cc I built last year. No big differneces in FR, but slight variances in detail and airyness of dialog can be effected, as well as bass punchyness. It's all in the ears of the listener.
...or is that in the "mind" of the listener????

Thanks again.
I like the fact that longer term, more experienced builders are willing to share with us who are less experienced.

Jeffrey8128

[curt_c]

Dennis, this is too funny. I’m in a similar situation, working on a large 3 way with a pair of 4” mids. Some posters may wonder what an awwwwwk coloration sounds like, but I know exactly what you mean, as I had the same phenomenon myself.

It took me some time to determine the cause of my issues. My solution included lowering the woofer fc from 400 Hz to around 250 Hz, to get the fc out of the intelligence band. As this design also utilizes a ribbon, I now have a nearly 4 octave midrange passband. Fortunately the mid drivers appear to be up to the task

I concur that your dispersion speculation appears to be spot on, although I’ve done other 3 ways with even smaller mids and crossed in the intelligence band with no issues. The design I’m currently working on is a WMTMW, and I wonder if the widely spaced woofers are also contributing to the issue somehow.

C

[curt_c]

Hi Jeffrey,

Of the two enclosure designs, I prefer this one, as it ties the front and back baffles together, and also braces the side panels. I'd probably suggest rectangular holes (window pane type) rather than the circular ones to mitigate any potential cavity resonances.

Potentially there will be a lot of acoustic energy to dissipate in these cabs. Besides the conventional stuffing, I’d also suggest some sort of constrained layer construction lining the walls, and perhaps spring for something like Deflex panels for the back panels of the woofer and especially the mid enclosure.

Holler if I can be of further assistance…

C

[jeffrey8128]

> Hi Jeffrey,

> Of the two enclosure designs, I prefer this
> one, as it ties the front and back baffles
> together, and also braces the side panels.
> I'd probably suggest rectangular holes
> (window pane type) rather than the circular
> ones to mitigate any potential cavity
> resonances.

> Potentially there will be a lot of acoustic
> energy to dissipate in these cabs. Besides
> the conventional stuffing, I’d also suggest
> some sort of constrained layer construction
> lining the walls, and perhaps spring for
> something like Deflex panels for the back
> panels of the woofer and especially the mid
> enclosure.

> Holler if I can be of further assistance…

> C

wow - Thanks Curt. I'll keep all that in mind.

I never saw this Deeper enclosure. the last one I saw was 16". Good thing I didn't cut wood.

I like the window design in bracing myself.
One iteration I did on my version of the cynosure was a double brace across the width of the box with large windows on front brace, and more smaller windows on the back brace. total sq.in. open space in braces was close to the same. I rounded all openings. I "feel" that this helps break up standing waves as there is not a straight path behind the drivers.

[curt_c]

<A HREF="http://www.htguide.com/forum/showpos...&postcount=395">http://www.htguide.com/forum/showpos...&postcount=395</A>

[Jeff B.]

> Dennis, this is too funny. I’m in a similar
> situation, working on a large 3 way with a
> pair of 4” mids. Some posters may wonder
> what an awwwwwk coloration sounds like, but
> I know exactly what you mean, as I had the
> same phenomenon myself.

> It took me some time to determine the cause
> of my issues. My solution included lowering
> the woofer fc from 400 Hz to around 250 Hz,
> to get the fc out of the intelligence band.
> As this design also utilizes a ribbon, I now
> have a nearly 4 octave midrange passband.
> Fortunately the mid drivers appear to be up
> to the task

> I concur that your dispersion speculation
> appears to be spot on, although I’ve done
> other 3 ways with even smaller mids and
> crossed in the intelligence band with no
> issues. The design I’m currently working on
> is a WMTMW, and I wonder if the widely
> spaced woofers are also contributing to the
> issue somehow.

> C

You guys are right on the nose about 3-ways in general. Designing crossovers for 3-ways is a full order of magnitude more difficult than 2-ways are to do if you really want them right. After doing a couple big 3-way designs a simple small 2-way is a walk in the part to get right. I also agree that with 3-ways especially, the shallower slopes give much more coherence. I think that is one of the things that I have always found issue with on B&W 801's, although flat, something just didn't seem right, and I always felt it was the 4th order crossovers. In my current home speakers, which use two woofers, using simple circuits gets me excellent BSC and excellent intergration with the midrange, which I have always found to be the most difficult part of getting any 3-way right. Just echoing you guys a little.