Handmade Ersatz M9500 Speakers

[linear]

Charles,

I agree with everything that you say, including "I guess all I can do at this point is just build them and see what happens."! Please let us all know how everything works out for you.

Regarding how my particular setup sounds, well that's a very subjective thing! My wife really likes them, and she would have to, to even allow these monsters in our living room. To try to get more specific, brass and woodwinds (saxophones, trumpets, clarinets, etc) sound fantastic with the wooden horns. The classic Swedish session "Jazz at the Pawnshop" never sounded better to me. You can close your eyes and swear that you are right there in the "Stampen" Club! In this regard, I can highly recommend the new XRCD and SACD pressings available from www.fimpression.com .

Now, regarding bass performance, I'm a musician (electric bass player, actually) and I really like how my system sounds with contemporary (rock, jazz, etc) "low end". For example, the "remixed" version of "Come Together" from the new Beatles "Love" CD is just amazing. (This is George Martin's favorite Beatle's track, according to the liner notes.) McCartney's bass is swampy, smooth, but atriculate......just absolutely great. I wish I could get that exact sound myself, but somehow I just can't seem to get the "slide" spot on!

However, a few years ago, I purchased a couple of the JBL 1500 SUB speakers that Parts Express were "blowing out". I installed them in cabs almost identical to the first Revel subwoffers and I drive them with almost 1000 watts each, through an electronic equalizer that I built. I use this rig for my bass guitar (Steinberger L2), but once I did try them as a subwoofer add-on to the system described in this thread. They certain DID add more low end, but mostly it was only noticeable on "earthquake" or 16 Hz organ pedal stuff. I'm not really into home theater or organ very much, so the D2 type system suits for our listening tastes. (There's no room for the subs anyway, and my wife would kill me if I were to suggest it as a permanent thing!!)

Again, please let us know how it all sounds to you, Charles, when you finish your project.

Linear

Hi Linear,

Thanks for getting back with me! I really appreciate it.

Yep, PE is where I plan on buying them. In fact, in just a few minutes I'll be placing the order!! Although, everyone at the moment is selling the 15HM's at that price, so it must be a manufacture special.

In your plot, it's the same exact reading I got in WinISD Pro. Ovbiously, it would be since the T/S parameters and enclosure specs are the same. Still, at 1 watt input, it says 82dB @ 20Hz for ONLY one driver.

Neither one of these plots take into account room gain or the fact that there will be THREE more identical drivers and enclosures in the same room supporting eachother. Once you add the other three drivers, you're up to 90-91dB @ 20Hz, then when you add in room gain, that's about another good 4-6dB, give or take... BTW, room gain in my room comes in strong in the sub-30Hz range, which is a really good thing.

On top of that, that's still not including the two other enclosures that make up the center channel. However, I think I will have them crossed over at 50Hz instead of playing fullrange. I've found that when you have the center set to fullrange, most of the bass goes to it instead of the mains. I'd rather that bass for to the main channels.

I guess all I can do at this point is just build them and see what happens. I must say though, even with the Cornwalls playing full range in my room (they're tuned to 37Hz), the low pedal notes can still somewhat be heard and felt. So with that in mind, I think 4 cabinets tuned 10Hz lower with twice the woofer-age might just pull this off.


So, what about your setup? You still haven't mentioned how they sound, how their bass extension is in your room, etc, etc...

Thanks again,
Charles

[ChopsMX5]

Hi Linear,

I certainly will let you ALL know how this project turns out. It's funny that you mention that you play electric bass and that you'r a musician. Back in middle school and highschool, I played string bass. Four of those six years, I was 1st chair bass, the last three years of which was a rather large 101 piece orchestra. Boy, those were the good ole' days (13+ years ago). In the hopes of re-discovering my musical tallent, I purchased an Ibanez 5-string bass about a year ago. I was able to pick it up and start playing along to various CDs right away, just by ear. I thought I'd enjoy playing jazz or blues, but apparently, it's not my thing. I'd much rather be playing classical music with a string bass in a large orchestra again. So needless to say, the bass just sits there now.

Anyway, I wonder how much low end you're missing due to only have two 10cf enclsoures tuned to 27Hz, and the fact that they aren't in or near the corners of the room.

See, not only will I have four 10cf enclosures, all tuned to 27Hz, but I have no choice but to place them smack-dab in the corners of the room. So who knows, I might just get the bass extension I'm looking for.

I'm also going by what Bill from Response Audio said about the Usher D2 system when he had them in his showroom. He said that he had measured their response down to the lower 20's/upper teens, and that was powering them with flea-powered SET amps. Since the drivers I'm getting are the same and the enclosures will roughly be the same (although he says the D2's are 7cf each, not 10cf), and he had them pretty much positioned similar to your setup (away from the corners), there's a very good possability of getting some extra deep bass out of these things.

If anything, I can give them a little boost with my EQ if need be (although I'd rather not), and if I decide to use my Crown XTi 1000 amp, that's 500 watts per channel into 4 ohms. That would be more than plenty oomph to motivate them.

We'll just have to wait and see what happens. Obviously, I'm very anxious to get the ball rolling on this project, and even more anxious to get it finished and running.

BTW, I just wanted to ask a couple more questions about your speakers...

What does the staggered tuning do for the sound in your system rather than going the route I am, besides the fact that you were going after the M9500 design?

What kind of accoustic treatment did you use inside your enclosures, foam, stuffing, both? And how about bracing?



Again, I'll keep everyone here updated on this project as well as document the entire build. In fact, last night I put in the oder for the 4 Usher drivers, 6 pairs of satin nickle plated binding posts (the ones that go straight through the wood), and finally, that Jazper circle cutting adapter for the router.

Thanks again Linear for shedding some light on this subject. I really appreciate all the information you have provided!

Charles

[A9X]

I use this rig for my bass guitar (Steinberger L2)

Another bassist. My main axe is an XL2.
Great speakers.

[linear]

A9X,

My L2 was one of the last made before they switched to the XL2. If you're not already a member, you should join the Steinberger yahoo group:

http://launch.groups.yahoo.com/group/steinberger_world/

Great info and discussion.

Now back to topic.

Charles,

Yes, you are right. I am loosing some low end response due to the fact that the upper cabs are smaller. Originally, I wanted to emulate the JBL M9500 system. JBL marketing claimed (at the time) that stagger tuning, or "imaginary Equivalent Tuning" (IET), as they called it, provided a "better balance between the high speed of Bessel tuning and the flat frequency response qualities of Butterworth tuning".

Also, at that time, Greg Timbers, the JBL design engineer involved with this IET project, "felt that by having different volumes and different tunings, we could spread the various enclosure and tuning resonance frequencies over a (wider) range, making them less of a problem".

However, there is the school of thought that all these resonances just merge into a single 4th order system anyway. Mr. Timbers was kind enough to post his "latest" thoughts, about all this, on this forum about 2 years ago. Please see:

http://audioheritage.org/vbulletin/s...&highlight=iet


Regarding construction details on my speakers, the smaller upper cabs have one brace, running side-to-side at about the middle. The larger bottom cabs have a full "shelf", with two large holes in it, at the point where it's volume equals the top cab. The volume above this "shelf" is around the wooden horn and driver, and brings the volume up to about 10 cf. There is also a side-to-side brace across the bottom half of the bottom cab. Everything is constructed out of 1 inch thick MDF.

Originally, I lined all internal walls, except the front face, with about 2" of pink fiberglass. However, this ADDED to much additional effective volume to the cabs, and changed the tuning. So, I cut the fiberglass back to about 1" and everything measured OK at 28 Hz and 35 Hz for the large and small cabs respectively.

Linear

[ChopsMX5]

Charles,

Yes, you are right. I am loosing some low end response due to the fact that the upper cabs are smaller. Originally, I wanted to emulate the JBL M9500 system. JBL marketing claimed (at the time) that stagger tuning, or "imaginary Equivalent Tuning" (IET), as they called it, provided a "better balance between the high speed of Bessel tuning and the flat frequency response qualities of Butterworth tuning".

Also, at that time, Greg Timbers, the JBL design engineer involved with this IET project, "felt that by having different volumes and different tunings, we could spread the various enclosure and tuning resonance frequencies over a (wider) range, making them less of a problem".

However, there is the school of thought that all these resonances just merge into a single 4th order system anyway. Mr. Timbers was kind enough to post his "latest" thoughts, about all this, on this forum about 2 years ago. Please see:

http://audioheritage.org/vbulletin/s...&highlight=iet


Regarding construction details on my speakers, the smaller upper cabs have one brace, running side-to-side at about the middle. The larger bottom cabs have a full "shelf", with two large holes in it, at the point where it's volume equals the top cab. The volume above this "shelf" is around the wooden horn and driver, and brings the volume up to about 10 cf. There is also a side-to-side brace across the bottom half of the bottom cab. Everything is constructed out of 1 inch thick MDF.

Originally, I lined all internal walls, except the front face, with about 2" of pink fiberglass. However, this ADDED to much additional effective volume to the cabs, and changed the tuning. So, I cut the fiberglass back to about 1" and everything measured OK at 28 Hz and 35 Hz for the large and small cabs respectively.

Linear

Hi Linear,

I can see where one would think of the staggered design helping in that way. And thanks fot the link to the other thread. That was a good read as well!

So everything is 1" MDF, even the baffles. I assume the enclosures are plenty ridged enough then. Since these drivers have such a low Xmax, I guess they don't put too much stress on the enclosures.

When I build mine, I plan on using joining biscuits in all the joints along with small strips of wood running the entire length of each joint. Then I'll have 2 verticle shelf braces behind the drivers. The horn enclosures will be built in a similar fashion, minus the shelf braces, so it can support the weight of the top bass cabinet.

Do you think it is absolutely necessary for the front baffles to have edge bevels, especially considering the fact that the drivers will be surface mounted? I guess that might be a stupid question since both Usher and JBL have edge bevels on the D2's and M9500's. If you completely ignore this question, I'll know why.

Thanks,
Charles


BTW, the Usher 15HM drivers came in today. I took one out of the box just to check it out... WOW, these suckers are massive! Very nice, well made drivers. Sure, they may not be JBL's, but they aren't cheap junk either. I just hope I can get them to perform as good as they look!

[linear]

The edge bevels are probably more of a cosmetic thing than anything that will dramatically affect acoustic performance.

The easy way to do the bevel is to use two 1/2" thick pieces of MDF for the front baffles, cut a hole in each, of the appropriate different diameter, and them glue and clamp them together. Voilà, a 1" thick front baffle with a bevel.

The 15HMs are good speakers for the money. However, if anyone on this board, or at JBL, want to give me four JBL 1500AL speakers (like was done with Project May), I will swap out those 15HMs in a heartbeat!!!!!

[ChopsMX5]

I was kind of thinking that the bevels were a little more cosmetic than anything else, but I didn't want to say it. Doing without it will definately ease the build.

I'm just banging my head on what to do as far as design goes. Over on the DIY Audio site, there's a pretty knowledgable guy there by the name of GM. He's been shooting back and forth with me about this project, and is telling me that an MTM is not the best choice for my 511B horns and that I would be better off with the 15's horizontally opposed like the 4435 or K2 Everest. Something about the 511's inability to match the 15HM's polar response in an MTM setup.

So it seems that the final design is still in the air until I can get something figured out. Hmm...

[Zilch]

http://www.altecpro.com/pdfs/vintage...0HF%20Horn.pdf

[ChopsMX5]

http://www.altecpro.com/pdfs/vintage...0HF%20Horn.pdf

Hi Zilch,

I have these data sheets downloaded from over a year ago when I was thinking about buying the Altec horns and drivers. Unfortunately, I don't understand some of those charts.

If you could explain to me what the charts say and how the polar response of the 511's would match up to the 15HM's, I would really appreciate it a lot.

Thanks,
Charles

[Zilch]

Go to the Eargle sound reinfocement manual on the JBL Pro website, in the technical library, and look up the chart on beamwidth of woofers. It varies with frequency and driver diameter. What's the beamwidth of a 15" woofer at your crossover frequency?

Then look at the 511 beamwidth plot. What's the horizontal beamwidth at that same frequency, and are they comparable?

I look at the 511 plot, and at 1 kHz, it's in the range of 90° - 100°, and JBL's 4430 used 15" 2235H at that frequency, stating that 100° was a good match.

You need to do a similar comparison for your design.

From the Project May design work, it's apparent that MTM is not a slam dunk, and from my own experience, neither is dual woofers horizontal. Look at the bandwidth the "Helper" woofer in E2 is playing, and how it mates with the main to accomplish a bass extension design objective. It's clearly not just a matter of throwing two woofers in a box and hooking them up.

[Ian Mackenzie]

[quote=Zilch;182909
It's clearly not just a matter of throwing two woofers in a box and hooking them up.[/quote]


Who said it ever was.......where's Giskard when you need him....

[ChopsMX5]

Go to the Eargle sound reinfocement manual on the JBL Pro website, in the technical library, and look up the chart on beamwidth of woofers. It varies with frequency and driver diameter. What's the beamwidth of a 15" woofer at your crossover frequency?

Then look at the 511 beamwidth plot. What's the horizontal beamwidth at that same frequency, and are they comparable?

I look at the 511 plot, and at 1 kHz, it's in the range of 90° - 100°, and JBL's 4430 used 15" 2235H at that frequency, stating that 100° was a good match.

You need to do a similar comparison for your design.

From the Project May design work, it's apparent that MTM is not a slam dunk, and from my own experience, neither is dual woofers horizontal. Look at the bandwidth the "Helper" woofer in E2 is playing, and how it mates with the main to accomplish a bass extension design objective. It's clearly not just a matter of throwing two woofers in a box and hooking them up.

I looked around on the Pro site for a quick few, but didn't find the chart you were talking about. I'll go back and look some more, unless you have the direct link. Does it mention the chart(s) anywhere in the titles?

And what's this "helper" woofer you're referring to in the E2? In fact, what is the E2?

And yes, I know there's a lot more involved that just throwing a couple of drivers in a box. I don't come off looking that hopeless, do I?

[Ian Mackenzie]

Not at all..its an in joke with Baron Von Zilchmeister

[Zilch]

I think the chart is in the Eargle Sound System Design Manual here:

http://www.jblpro.com/pages/tech_lib.htm

E2 is Everest II, mentioned by your reference "GM," presumably, because that's the one with horizontal dual woofers.

There's a white paper linked in the forums that'll show you what's up with that design.

4435's dual woofers were ultimately built in separate chambers, I believe, so there may have been some evolution there. I've never opened mine to see what's up with them. Looks like I've got some of each kind, judging from the crossover location on the rear.... :dont-know

[ChopsMX5]

I'm sorry, but I think I have hijacked this thread...

I'll start a new thread of my own. Sorry Linear!