Large floorstanding, "Project 110db"

**jkrutke** · 13 July 2007, 18:27 Friday

Originally posted by cujet

5) I have read that lower Xmax drivers sound better, true?

I just wanted to pop in and submit a quick comment on that.

Many people read my little article on the subject and simplify it a bit too much. You can't say lower Xmax drivers always sound better, you have to look at the whole picture if you are comparing drivers of different design. About all you could say for sure is that if two woofers shared the same design but one had shorter Xmax, the one with shorter Xmax would have lower distortion up to the point where it's Xmax is exceeded.

With woofer design, as the excursion requirement for a single woofer becomes higher, the overall design becomes harder to engineer, more expensive to manufacture, and susceptible to some specific design shortcuts that may result in higher distortion. Just be careful with your generalizations and realize that sometimes, a better route to take might be an array of well-designed lower Xmax woofers vs a single high Xmax woofer of lesser design.

I've actually got a stack of RS270's in their boxes sitting around waiting for me to do a multiple woofer project. A couple of those per side will satisfy my output requirements and do it with very low distortion. I was actually thinking of 4 per side but I'm a couple RS270's short of that.

**cjd** · 13 July 2007, 18:40 Friday

I suppose that would be a more natural extension of what I ha at home: WWMTMWW with four RS270's.

Craziness, I say!

Tweeter would absolutely be the weak link. But I think I can actually retrofit waveguides on the existing baffles without having to disassemble a thing. Have you tested the RS28 in the MCM WG at all Zaph?

C

**Brian Bunge** · 13 July 2007, 18:45 Friday

Originally posted by cjd

I suppose that would be a more natural extension of what I ha at home: WWMTMWW with four RS270's.

Craziness, I say!

Tweeter would absolutely be the weak link. But I think I can actually retrofit waveguides on the existing baffles without having to disassemble a thing. Have you tested the RS28 in the MCM WG at all Zaph?

C

Great! Yet another tweak for me to consider if I end up living with these for several more years...

**jkrutke** · 13 July 2007, 22:04 Friday

Originally posted by cjd

I suppose that would be a more natural extension of what I ha at home: WWMTMWW with four RS270's.

Craziness, I say!

Tweeter would absolutely be the weak link. But I think I can actually retrofit waveguides on the existing baffles without having to disassemble a thing. Have you tested the RS28 in the MCM WG at all Zaph?

C

I haven't touched an RS28 in a while. I'm due to get a new pair someday to see if the performance has improved. Maybe Mark K can comment on recent production runs.

The TBFCG wouldn't fit my current waveguides because of the Hexagrid, but the DXT version is coming out soon anyway. I bet you could easily pop one of those in there and it would probably work down to 1200 hz without issue.

**cujet** · 13 July 2007, 23:13 Friday

jkrutke said ""I was actually thinking of 4 per side"" I like that idea very much, but how about 3 per side?

By the way, thank you for the Xmax comments. I had not read your writeup on Xmax when I posted my question. This is something I had heard (and personally believed) many years ago. I was not sure if it was still an issue.

Chris

**AJINFLA** · 13 July 2007, 23:32 Friday

Originally posted by jkrutke

I bet you could easily pop one of those in there and it would probably work down to 1200 hz without issue.

I think that is a bit optimistic given what looks like maybe a 5-6" sized horn.
Diffraction rings to widen dispersion are interesting.

The OP ought to be looking at pro drivers for the type of SPL desired. A direct radiator tweeter is going to be under serious duress (with corresponding SQ) at those levels.
I think what is missing also is the huge impact of the room when he is listening to different rigs. Some nice threads recently on DIYAudio in this regard.
You know Zaph, with the phase plugs/no pole vent and low mechanical noise at high excursion, the RS270's make very nice dipole woofers. Just in case you were wondering if in multiples, they can do things other than "slam"

.
They get to enjoy more fresh air that way too.

cheers,

AJ

**cujet** · 15 July 2007, 00:31 Sunday

Just got back from the Deep Purple w/Steve Morse concert. Johnny Winter opened. The sound was great!

I would love to come close to the punch, clarity and overall feeling of a concert. It sure would be nice to know the science behind concert audio. I always notice that drums hit hard. And not just the bass drums.

This time, I paid close attention to the abundant very low frequencies. They are well reproduced without strain. Even the very lowest. But, during some concerts I notice the lows do not go much below around 60HZ. I suppose it depends on the material played and the instruments used.

Chris

**cujet** · 19 July 2007, 18:57 Thursday

"Project 110db" is name for this.

Chris

**cjd** · 19 July 2007, 19:17 Thursday

So yeah. Concerts don't actually go that low usually. A bit of boost around 50Hz is the norm. And LOTS of displacement.

**joecarrow** · 20 July 2007, 01:52 Friday

I'd just like to second what people are saying about how much trouble dome tweeters are going to have reaching 110 db at 15 feet. The standard is to measure at 1 meter, 3 feet, so at that standard distance we're talking about over 116 db. That's a solid 10 db beyond what most dome tweeters will sustain.

Some options I see include:

-A large format"pro" ribbon

-A conventional dome in a waveguide

-A high quality pro compression driver in a waveguide; I believe there's a BMS driver that people are drooling over for this.

You're right about the bass not going much below 60 hz- most pro gear doesn't even attempt it, and instead just goes for lots of output. Since the lowest string on a bass is about 40 hz, the argument is that we don't miss that much. I think that the stuff down lower than that gives us the room's reverberation and a physical feeling of "Hey, that drum is really 20 feet away from me, right over there", and is a part of why you really can't mistake it when you're in a moderately small room with a live acoustic band.

I say that the tweeters are the weak link, but really- the whole system is under stress. In my opinion, dome mids are right out the window. Ported woofers are also very attractive, along with infinite baffle subs.

**cjd** · 20 July 2007, 09:13 Friday

I think 110dB is a dangerous goal anyhow. That's permanent hearing loss range.

Hell, I don't like listening at 94-95dB for extended periods. Normally around 65dB @ 2M

C

**---k---** · 20 July 2007, 09:29 Friday

I have my doubts that anyone is actually going to listen to a speaker at 110db in a normal room for extended period of time. I know that the rs meter was used to measure, but I have some doubts about the accuracy of the reading.

I think 110db is just a cool number to shoot for. Maybe after he hears Brian's 3-ways and the Statements, maybe the goals will be adjusted?

**Brian Bunge** · 20 July 2007, 09:40 Friday

Well, he has heard my 3-ways already. I'm always a little cautious about continuing to "turn it up" during sessions but I can tell you I could have easily turned it up more. I'm always worried about clipping the amps in my receiver and/or damaging the tweeters. The only time I've pushed the tweeters too far was when cranking up some music from a local FM station. The background "hash" made for some nice crackling noises coming from the tweeters. Not something I want to experience again.

I'm sure Chris was hoping for a little more impact from the bass, but in my family room (which is wide open to the kitchen as well as the formal dining and living rooms) that's hard to come by with most of the music I have. Maybe I should have put in one of my 3 rap CD's (Run DMC's Raising Hell, Sir Mixalot's Swass and Rehab's Graffiti the World) for more ideas of what kind of bass these have.

I'd imagine Chris would prefer the 10's in a smaller enclosure, which gives a higher system Q and a more punchy bass sound. Like you guys have said, most pro gear doesn't do much below 40Hz, but what it does do it does loud. Either that, or he should look at bass drivers in a ported enclosure.

**joecarrow** · 20 July 2007, 09:56 Friday

Originally posted by cjd

I think 110dB is a dangerous goal anyhow. That's permanent hearing loss range.

Hell, I don't like listening at 94-95dB for extended periods. Normally around 65dB @ 2M

C

Although it's true that you can (and would) damage your ears by listening that loudly, I think there's really something to be said for headroom. I too generally listen in the 65 db range, going up to a bit below 80 db when the mood strikes me. Two things stop me from going much higher. First, I have neighbors above, below, and to the side. Second, it does start to sound a bit congested on peaks when I push it that far, and the base level really isn't as clean anymore.

The only reason why I'll ever want to shoot for 110 db (and I do some day, or at least 105), is to better be able to handle the short, loud, events in movies. If the average is 65 or 70 db with an really short 105-110 db peak, is it really that dangerous if it's only repeated a few times per hour? Maybe it's like those other things in life that are just more fun with a little danger.

**Tommythecat** · 20 July 2007, 11:05 Friday

You wont find many movies/music with peaks that high. I almost guarantee it. +20db peaks are rare (okay, maybe not subbass in some movies).

And like many others have stated, yes - 110db sustained is damaging to your ears and most likely your tweeters if you try to use "home" diy drivers aka dome tweeters.

Doing 105-110db C weighted for 30 min isn't too bad. But I wont screw around. I wont listen without a "pain filter" around 3k - very narrow band of EQ about 5db down depending. And then I like a system that's downward tilted, and 2" compression drivers typically give you some of that rolloff towards 20k.

**cjd** · 20 July 2007, 11:36 Friday

I've listened there with the 3-ways (~2.5M). It's hard to do for long. I can't tell why my ears cry, whether it's tweeters crying, midrange muck, or just too loud in general. Bass is absolutely there. I usually find myself way too loud listening to Depeche Mode, think it's track 6 on "Songs of Faith and Devotion" where the opening sequence is all bass, wanders around a bit, and is just so much fun.

I've had some classical peak out over 100dB too - that's about the only music that really HAS that kind of dynamic range (>40dB measured for a couple tracks I have - not entirely sure because it actually went off the bottom of the SPL meter at times where I could still hear it clearly).

So, headroom is one thing. It's there. Being able to sustain playback... very different game.

**JoshK** · 20 July 2007, 13:01 Friday

I typically listen in the 75-85db range....I was listening at Dr. Geddes place, at what he said was 120db C-weighted briefly and it didn't seem that loud until I tried to talk to him.

**Brian Bunge** · 20 July 2007, 15:32 Friday

Originally posted by cjd

I've listened there with the 3-ways (~2.5M). It's hard to do for long. I can't tell why my ears cry, whether it's tweeters crying, midrange muck, or just too loud in general. Bass is absolutely there. I usually find myself way too loud listening to Depeche Mode, think it's track 6 on "Songs of Faith and Devotion" where the opening sequence is all bass, wanders around a bit, and is just so much fun.

Chris, it's nice to hear that you do listen to some normal music, too!

Is that their latest CD from a year or two ago? I think I have that one around here somewhere. That and Violator. It makes for some fun listening as well.

**cujet** · 20 July 2007, 16:44 Friday

I have got to admit this is a heck of a lot of fun!

Originally posted by cjd

I think 110dB is a dangerous goal anyhow. That's permanent hearing loss range.

Hell, I don't like listening at 94-95dB for extended periods. Normally around 65dB @ 2M

C

All true, but even more so than Brian's house, my house is a large open planform. My listening room has dimensions, but it is very open to the rest of the house.

In my past house, my little "den" was my listening room, and it rocked! My little dual 6.5 speakers filled the room with plenty of power.

I guess I am asking the speakers to fill the kitchen, living room, breakfast area, hallway, entryway, den, dining room and any other nearby space. By the way, the house has 13 foot ceilings and the listening room 11 foot. Maybe 1100-1300 sq feet of area.

I am doing my homework and research. One thread mentioned room over-pressurization due to large speakers. Is this simply high SPL? or something else?

Also, my current setup is NOT able to achieve 110db constant. Being able to achieve this would mean cleaner sound in my home.

I have a calibrated, industrial sound level meter, not a RS cheap unit. It is used for aircraft sound measurement during flight. I conduct sound surveys to determine noise levels at certain points inside the cabin, at various altitudes, airspeeds and cabin pressure levels. While I am not an expert in speaker design, I do understand how to take quality measurements of my very distorted sound system

Brian, it is unlikely that I would want your drivers in a smaller box. A sealed system with a high Q is annoying to listen to. Have you tried stuffing your enclosure to see what happens? Also, I do not know how much power you are running. But it is likely that with my Adcom amp those 10 inch woofers would be displacing much more air!

I am strongly considering Brian's 3 way design, maybe with a waveguide.

Chris

**Brian Bunge** · 20 July 2007, 17:29 Friday

Chris,

Ah, so you don't like higher Q systems. That's good to know. With the rock concert conversations I assumed that would be appealing to you.

I am running 100W/channel @ 8 ohms (not sure what the receiver does into ~ 3-4 ohms). I'd love to see what they would do with some real power behind them. The enclosures lined with PE's 1" Sonic Barrier material and are stuffed pretty heavily so I don't think there's much to be gained by adding more. IIRC, Qts should be in the lower to mid .6 range.

**kingpin** · 20 July 2007, 23:05 Friday

I can say the RS 3-ways can definetely play loud to 105-110db. But it better be clean or you will not like it too much. I normally listen to music at -80 to -90db. I can tell you the rs270's don't even move at these volumes. I do have the 12's running 6db hot, I think because they are up in the air and not on the floor like most conventional subs.

Mike

**cjd** · 21 July 2007, 10:12 Saturday

I just tested. C-weighted, slow response, MAX: average around 100-103dB is quite listenable, no problems, no ear pain. You feel it in your chest, you know?

When the song cranked up to 110dB things start to go in the tweeter - it just picks up distortion. It doesn't bottom out or anything, but it's definitely not in its comfort zone any more.

I'm running a pair of Outlaw 2200 (~200W into 8ohm, so over 400W I would guess) Monoblocks driven by a balanced pre-amp (twisted pear kit) which is 6dB of gain on a single ended source (I'll have balanced input for 12dB gain once I finish up the DAC).

And now back to Harry Potter...

C

**cjd** · 21 July 2007, 11:59 Saturday

One more comment:

Lots of people judge a home stereo system by how they FEEL the sound, causing it to fall short of a live concert. It's NOT the system, it's the recording, at fault. I was just listening to Peter Gabriel (Secret World) with it cranked to the low 80dB range, and the bass was solid and visceral. Absolutely felt it, both through the floor/chair and in my chest. Most albums, not so.

**Brian Bunge** · 21 July 2007, 12:09 Saturday

Chris,

I know exactly what you mean. I have albums that are exactly the same way. Because you can feel the energy in the music coming through the speakers (furniture, floor, etc.) it adds that little something extra.

Oh, and I'm really jealous! I want your Outlaw amps!

**Jonasz** · 21 July 2007, 17:17 Saturday

The TBFCG wouldn't fit my current waveguides because of the Hexagrid

Zaph, the grid is easy to remove!

Faktiskt.se har upphört - Faktiskt.se

http://www.faktiskt.se/modules.php?name=Forums&file=viewtopic&p=250608#250608

**Dennis H** · 23 July 2007, 00:48 Monday

Originally posted by cjd

And now back to Harry Potter...

C

Too funny. I was jealous you already had it and then I went out and got the mail and there was a box from Amazon so we all know how I spent the weekend.

It's a good read, Rowling rocks.

**JonMarsh** · 23 July 2007, 09:34 Monday

I'm jealous- instead of reading one of a pile of new books I have, I spent a day and a half this weekend working on a technical paper that badly needs to be updated on the company web site (last version, written by employees no longer with the company, dated 2001, doesn't touch on the current product). Something the home office should be doing, but they're swamped and understaffed, too, and have a European summer work ethic (at least this time of year). I've ben griping about this paper for over a year- they must of realized that like the last technical paper they owed, if they put off working on it long enough, eventually I would get disgusted and do it myself.

**cjd** · 23 July 2007, 10:58 Monday

I just went to Target at 8am and picked it up. Actually, was Home Depot first to see if they had the drawer slides I need to finish my desk (I made the drawers yesterday - that is, Sunday). Only started the desk two years ago... Got home, made myself a nice big latte, grabbed some nosh, some tunes, the SPL meter, and sat back to enjoy the day.

Jon: this has to stop. Not just you and your company, but everywhere. It happens here too. It's not healthy culturally. Oh well. But really. There's this nifty word, "no" - most kids learn it before anything else, but clearly it was beat out of you.

C

**Hank** · 23 July 2007, 13:02 Monday

eventually I would get disgusted and do it myself.

Jon, they've got you pegged and are playing you like a fiddle. You're hooked though.
Hey, I'd like to have a nice free-time August, but no - gotta go to Shanghai to our plant, then to Shuzhou to our projector manufaturer, then to Taiwan for meetings.
Upside: frequent flyer miles.

**---k---** · 23 July 2007, 16:48 Monday

Originally posted by cjd

And now back to Harry Potter...

C

What?!?!?
Don't you have some testing to do.

**cjd** · 23 July 2007, 16:55 Monday

:lol:

Not only did I read Harry Potter, I went and made drawers for my desk! Didn't do one thing on your speaker this weekend. :P

It *is* on the dock for this evening, after the normal Monday chores.

C

**sprint_9** · 23 July 2007, 17:07 Monday

Darn it C your PM box is full and Im a newb with alot of questions, which by the way you are doinig a fantastic job of answering.

**---k---** · 23 July 2007, 19:39 Monday

You could always start a thread. We don't mind.

**---k---** · 23 July 2007, 19:43 Monday

Originally posted by cjd

:lol:

Not only did I read Harry Potter, I went and made drawers for my desk! Didn't do one thing on your speaker this weekend. :P

It *is* on the dock for this evening, after the normal Monday chores.

C

I would send you a PM to say that's okay, but apparently you box is full.

**JonMarsh** · 23 July 2007, 20:16 Monday

Originally posted by Hank

Jon, they've got you pegged and are playing you like a fiddle. You're hooked though.
Hey, I'd like to have a nice free-time August, but no - gotta go to Shanghai to our plant, then to Shuzhou to our projector manufaturer, then to Taiwan for meetings.
Upside: frequent flyer miles.

Damn, Hank- you're worse than I am! I'm just going to the East Coast for a week in August, then turning around on Friday (the 17th) and leaving for a week in Singapore.

Hey, but you know, deficit spending has it's price- in order to save money, the company insisted that people like me take a certain percentage of PTO by the end of the fiscal year (end of September). Of course, you know what's happened, after scheduling it in a distributed way over the summer, my immediate managment asked me to defer a couple of times for "critical" activities, and now I'm going to have three straight weeks off in September in order to meet the "big management" deadline! Whoo Boy! Can you imaging that? I can't.... don't remember what it was like. And then I still have a week scheduled in October for the RMAF. And it looks like I may be in Europe for a week on business in October, too.

I told them it would just be easier for everyone if I just took the last quarter off, but for some reason that bothered them.... :rofl:

Travel safe, Hank.

And now, back to our regularly scheduled OT programming of Harry Potter commentary. :B

**cujet** · 23 July 2007, 20:17 Monday

Still digesting it all,

What do you think about the HiVi M12 woofer. That looks promising.

I read a writeup by JonMarsh about this driver, and it looked good. Do you think it would work well sealed?

JonMarsh wrote: ""Well, the "back of the napkin" calculations are complete (using Unibox, BDS, and LSPCAD, of course- I have a "digital napkin" and it looks very promising for an X1 UPGRADE in performance in an smaller box, actually.

The way it works out, with dual M12's in each 120 liter bass cabinet, I can tune the system to 22 Hz with a six inch downward firing port existing in the plinth area, which is elevated by spikes anyway. Each cabinet would be capable of 110 dB anechoiclly down to 20 Hz, and that's only using 5 mm of the available 7.3 mm Xmax. LF sensitivity is nominal 93 dB for the two drivers wired in series, but that's half pi; once you factor in baffle step, interface with the upper module, room gain, etc, the net broadband system sensitivity would come in somewhere around 89 (pessimistic estimate) to 91 (optomistic) dB. Let's call it 90. Now, most single high performance drivers do 89-90 dB, but by the time you put in the baffle step you need for a 6" driver in a small box, the real world sensitivity is about 85 dB. Some systems, like those using Excel drivers with BS comp, get as low as 83-82 dB, depending on crossover insertion loss (Joeseph Audio RM33si, for example).""

Chris

**JonMarsh** · 23 July 2007, 20:34 Monday

It COULD be real interesting, would require a largish cabinet due to T/S parameters, but when I was initially interested in it, couldn't find a distributor with it in stock. It doesn't have any copper in the gap, so though the cone is rigid and relatively well damped, it will have more inductivity modulation than say, an Aurasound NS12. Xmax is decent at 7.2 mm, but obviously it's not a sub. The real sensitivity is not as high as you might think, because they're specifying it with 2.83 VRMS into the driver impedance, which is 4 ohms, so that's actually 2 watts, not one watt. Real sensitivity is about 90 dB/watt, similar to the RS270. Similar to the RS270, it takes a big cabinet and tuning to go low- my guess is around 75-85 liters, without running Unibox. I wouldn't expect it to be as clean in the midrange due to inductivity modulation (no copper in the gap, judging from the impedance curve). Still, it's an interesting woofer for the price. It's a driver I'd like to have just to test and actually see it, but I don't think it brings as much to the party these days as the Aursound NS12a-513. If the M12 had been readily available a couple of years ago when announced, that would have been a different matter.

Qts is about ideal for ported- a little on the low side for sealed, unless you wanted a higher Fb, smaller box, and were going to use it with a sub below 40 Hz or so, i.e., a mid bass.

Just my 0.02. OTOH, if I had to do a less expensive M12ta, it would be something to consider. But for the extra money, sealed or ported, I'd go with the Aurasound.

But you need two if you really want 110 dB or more.

**cjd** · 23 July 2007, 20:36 Monday

You're mucking around with about the same basic numbers over and over. It's not the bottom end, it's the tweeter, where you've got issues with "standard" drivers.

**JonMarsh** · 23 July 2007, 20:47 Monday

Originally posted by cjd

You're mucking around with about the same basic numbers over and over. It's not the bottom end, it's the tweeter, where you've got issues with "standard" drivers.

Chris is right on the money, here.

What you need is a DDS ENG1 waveguide with an oblate spheroid expansion profile coupled with a BMS4540 compression driver. Total cost about $200 each set, i.e., $400 for a pair.

Sensitivity of about 110 dB/watt, power handling around 30 watts, of course, you need to EQ it flat, but the driver/waveguide combo extends to almost 30 kHz, and has very good pattern control over most of that range (see the plot above out to 45 degrees off axis- blows away any combo of tweeter and MCM waveguide- been there, tried that, discarded it).

Suggested crossover range of 1800-2000 Hz. Yeah, it's coming up in one of my current projects, a dipole system with 18" woofer, and high efficiency Accuton midrange. On the back burner until I get the "little" WMTW CC done. Maybe until I get the M12ta done, too. that's about a 106 dB (single speaker) system at one meter) system.

Be warned that waveguide/driver combos have a comlex impedance characteristic,

and you need a relatively sophisticated conjugate network to make them usable with a passive crossover.

But you can flatten it out quite nicely.

~Jon

**Brian Bunge** · 23 July 2007, 20:58 Monday

The M12 does not look very good sealed at all, IMHO. It's F3 is actually about 13Hz higher than the F3 of my dual RS270's (63Hz for the M12 vs. 50Hz for the 270). Now if you were willing to go ported, they look quite good in the enclosure Jon mentions.

EDIT: I see Jon and Chris responded while I was responding!

**cjd** · 23 July 2007, 21:19 Monday

I will say, I suspect a longer excursion tweeter (Millenium or one of the Scans, or even a different Seas?) over the RS28A and the smaller MCM waveguides probably would allow 110dB just fine.

C

**Tommythecat** · 23 July 2007, 22:17 Monday

I kinda doubt that, I can feel the spit from a dome tweeter on my face just thinking about it.

**cujet** · 23 July 2007, 23:38 Monday

Originally posted by cjd

You're mucking around with about the same basic numbers over and over. It's not the bottom end, it's the tweeter, where you've got issues with "standard" drivers.

cjd, thanks. I got it. Look at it from my point of view. I know what is important to me, so I concentrate on that. Sorry to seem so hard headed. I do understand the advice. Maybe the use of 2 tweeters of a particular flavor would get me what I want in that department?

jonMarsh, thanks. The Aura is a bit pricey (currently double) and maybe a bit low on SPL/watt. Meaning I would likely have to get more new stuff.

Still digesting.

Chris

**JonMarsh** · 24 July 2007, 09:07 Tuesday

$182 for the Aurasound vs. $132 for the HiVi M12? Sounds like about a 50% difference to me, not double. And that's with about 40% higher Xmax thrown in for the Aurasound.

The sensitivity difference is real, if one assumes the sensitivity specifications are accurate, but as mentioned, it's 90 dB vs 85 dB, and it's a function of T/S parameters- those that will allow more extended, deeper bass in a given size enclosure means less total sensitivity, or conversely, those that allow higher reference efficiency require a much larger cabinet for the same extension- just corollaries of Hoffman's Iron Law. It does mean that a system built around the Aurasound will need around 100 watts for it's ultimate bass extension and SPL as shown in the Unibox plot, though at higher frequencies, increased power would allow higher SPL. Something like an Emotiva RPA1 would probably fit the bill. Or a nice used Aragon.

Otherwise, if you plan to stick with your current equipment, you'll probably have to plan on a larger system physically - or limitations in LF extension which will diminish the transient impact on some program material.

Re tweeters, the only firm successfully using two tweeters in their designs, Dynaudio, rolls one of them off above about 8 kHz, to avoid excessive comb filtering. That's one approach; another would be doing a four way system with a dome midrange in a more limited frequency range (say, cutting in about 1000-1200, and shifting over to a longish throw tweeter at 3-4 kHz. The more crossover points, the more potential issues with integration, and of course, the more expensive and and development effort for the crossover. Paying attention to CTC spacing in the driver transitions is mandatory. Unfortunately, that is usually in opposition to selecting crossover frequencies for higher than normal power handling (the higher the frequency, the shorter the wavelength, the more problem with CTC spacing). (example: 4 kHz maximum recommended CTC based on wavelength is about 3-1/2". Requires a small form factor tweeter for good results.

**cjd** · 24 July 2007, 10:37 Tuesday

Originally posted by Tommythecat

I kinda doubt that, I can feel the spit from a dome tweeter on my face just thinking about it.

Only reason I say this is I'm able to do 103-105dB without real trouble, crossing the RS28A at ~1600Hz. I could be mistaken.

It's a close thing. If it's an issue of headroom vs actually wanting it to PLAY at 110dB constantly, I think this is reasonable.

If you really want to crank it to 110 and listen, that's a totally different game.

cujet: don't worry about being hard-headed. Rethinking is fine, asking questions gets you closer to your goal. As Jon mentioned, two tweeters is problematic in its own way. I'd rather see a jump to a 4 way.

C

Large floorstanding, "Project 110db"

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