Statement Monitor Build - Need Advise...

[composercody]

Hey Guys -

Long time lurker, first time poster - and I meant "advice" in the subject...heh. I decided to finally dive in and build a pair of Statement Monitors for my studio. I'm hoping I can use them as "B" speakers to my JBL LSR4300 5.1 system. I've been enjoying the building process but as a first time speaker builder I get nervous about certain steps.

I've been enjoying a nice correspondence with Curt, but figured I've bugged him enough and thought I'd poll this excellent community here.

I've got one speaker basically complete, and I brought it inside (with the front baffles clamped on!) to test. It left something to be desired in the lows especially - quite muddy. Now I'm using a crappy old Sherwood amp, but I still would have liked it to sound a bit better on the first pass. I also noticed the tweeter kind of "standing alone" in the mix of the drivers - I could easily pin point what was coming out of it individually.

I'm hoping the crossovers are all good, but don't have scopes to test to be sure. I went for the switchable design and am virtually certain I have the wiring correct. I did use pretty small wire on the boards themselves - 18 Gauge - possibly a Newbie mistake. For the connects to the posts and drivers I used 14 Gauge.

A few questions:

• Is there a way to test the crossovers without expensive testing equipment? I have good ears - would an oscillator/tone generator even from my iPhone etc suffice?

• There was a bit of air escaping the cabinets from the small seem at the baffle (since it's clamped.) I covered it with gasket tape and the bass response improved slightly. I'm hesitant to glue the baffles on before I get it sounding better. Is there a big negative to screwing it on now and covering the seems temporarily with gasket tape and then gluing later once I've got it dialed in?

•*I doubled up the 1" sonic barrier in the lower half, but there is currently none in the top chamber (behind the tweeter.) I might be out of sonic barrier by the time I finish the other speaker. I did find some polyester (fiberglass like) fill at a foam shop. Would I be advised to fill any air space with that to help dampen the bass?

• Kinda screwed up the scalloping on the inside of the baffles. I ended up doing the whole circle 3/8" round. That ok-ish?

• The cheap amp shut off a few times while I was testing the speaker - when things got louder actually...wondering if this can be pointing to something with the crossover?

Thanks so much for your time. The veneer doesn't arrive for a bit, so I'm happy to toy with it for a bit!

Here are some pics of the build so far!

[---k---]

The amp shutting off indicates to me that you have a crossover problem. I've never seen glue on the connections themselves. I don't know if that is a problem or not, but you'll need to clean that stuff off to check everything.

18ga wire is fine in the crossover. Clamping the baffle and a little air leakage is not optimum, but should not cause a great speaker to sound like crap.

I usually just keep everything twisted tightly together until it is working correctly and only solder after I'm happy.

I think you need to take your crossovers apart and look for shorts and make sure they are correct.

[Jim Holtz]

The build looks good. Here are some thoughts;

It's really hard to determine bass capability until you have the cabinet completely glued up and drivers installed. Double check the crossover and make sure its correct. The switchable crossover is one of the more difficult to build. Do you have the switch in place yet and how are you listening, near or far wall?

You don't need to line the cabinet walls in the top 1/2. I'd also suggest you remove some of the sound barrier that is blocking the paths on each side of the mid tunnel so there is a clear opening from the woofer to the top of the cabinet. The purpose is to kill sound wave reflections from bouncing back into the rear of the woofer. Stuffing makes a cabinet seem larger to the driver and also reduces bass.

F/3 with the new RS180 drivers is about 40 Hz. so it won't shake the walls, but it still should have satisfying bass for a 7" driver. If you're into heavy bass, add a sub.

I would suggest that you scallop the rear of the mid opening more or use a 3/4" roundover bit to open up the back of the front baffle more. Small drivers are very susceptible to "tunneling" with out extra care in this area.


Here are the switch instructions Curt sent me a long time ago.

"Here's a couple of switch p/n's you might try. One is with the typical quick disconnect type terminals, and the other one is screw, otherwise they are the same.

They both have a center off position which in the 'far wall' position only, of adding additional attenuation of the tweeter. IOW, I couldn't find a 3PDT switch without a center off, so we gain a somewhat dubious added feature."

http://www.mouser.com/Search/Refine.aspx?Ntt=691-HM251-73

http://www.mouser.com/Search/Refine.aspx?Ntt=691-HM254-73

and the data sheet:

http://www.carlingtech.com/pdf/s_h.pdf

Jim

[composercody]

Thanks much you guys! I'll do the following this weekend:

• Double check wiring (with amp shutoff etc.) I'm pretty sure I got the switch correct btw - made my head spin for sure!

• Reduce foam around tunnel.

•*Scallop 3/4" off mids.

I'll likely finish off the other speaker doing this - maybe that will help me troubleshoot.

Thanks again!

P.S. Any objections to screwing in the baffles? I'd countersink in the screw and glue it down the road.

[BeerParty]

How are you running the wires from the crossover to the mid? You'll want to make sure that the cabinet is airtight except for the port, otherwise the woofer will not perform properly.

If you are going to increase the scallop behind the mids, make sure that you don't scallop too much and encroach on the tunnel walls. I don't think it would hurt anything, but better safe than sorry.

Screwing on the baffle (with some gasket to keep it from leaking) so you can test before gluing the baffles should be fine. Just don't tighten the the screws too much or you'll strip the holes (MDF isn't especially weak, but it isn't oak either ). And, when you are ready to glue the baffle on you'll be able to use screws as clamps and not have to wait for the glue to dry. Since you plan to veneer, make sure wait for the fill in the holes to dry completely before sanding and adding the veneer. Otherwise it may shrink and cause a spot to telegraph through the veneer.

[composercody]

I dremeled out a little groove for the wire. I'll definitely hot glue it to make it air tight!

Also, I'm pretty sure the junk Sherwood amp I was testing with is not 4 ohm compatible. I'll move my testing down to my studio where I intend to drive it with my Technics SU-V6. That explains the amp shutting down though (I think!)

More testing later - thanks again!

[composercody]

OK, so I heard back from Curt as well and here's a newb mistake for ya! That crap Sherwood Amp was not a 4 Ohm amp! So I did what I should have done in the beginning, took it town to my studio where I could also A/B with my existing monitors. I also cleaned up the foam as Curt suggested.

I need a little more time to be sure, but it's sounding pretty damn good for a mono hookup! Whenever something "sounds" muddy to me I flip on the JBLs that are room calibrated and generally realize that it's in the source recording! I think I'll pad the bass just a bit with the amp though, it's slightly hot for my application.

I'll get the other speaker done soon, then I've got figure out how to mount these guys where I currently have those Yamahas!

[composercody]

Finished the other speaker this AM and just finished listening to a wide variety of tracks. These guys are amazing! I'm confident my previous problems were due to the amp not being 4 ohm compatible! The Technics sounds good, but am looking to possibly upgrade it once I get these puppies done and mounted. Anybody every mount these? Ideally I'd like them about a foot or two out from the wall. I'm trying to figure out if I stick with the DIY wood arms I've got the Yamaha hanging from or whether I rig up something new (potentially even an LCD mounting arm?!)

Thanks again to everybody here - and of course to Jim and Curt for designing such an incredible speaker!

[BeerParty]

Glad you are happy with them.

Why the desire to not use the arms you have? Do they not get the speaker far enough away from the wall?

[composercody]

Quick update. My this is a lot of work, but fun!

The LCD mounts work great. I can post pics if anybody is interested. I'll definitely post pics once they're up like this: