Mark K's MT RS225/RS28A

[mazurek]

In my opinion, the best solution is just to use appropriate wood/drywall screws with wide threads. My experience with T-nuts is that for a flange like that, they can mangle the MDF a bit because they are so close to the edge, hurricane nuts are prone to spinning, hurricane nuts plus epoxy might work. I would put nice metal threaded fasteners on the joint between your cabinet and removeable baffle, but just screw the drivers directly to the baffle.

[cgr]

So, as I was dry fitting the speakers, I realized I over looked one teeny-weeny little problem... how the hell do I mount them? I've heard of people using t-nuts and such, but would it work if I took small pieces of plywood and put them on the back of the front baffle to hold the screws? I'm trying to save a trip to the hardware store : )

I used t-nuts and squares of plywood on my subwoofer. For my LCR I used #8 screws and predrilled a 7/64 hole.(advice I received on this forum)

Are you using fasteners to attach your baffles or glueing them to the cabinets?

[Gir]

I was going to use fasteners to attach it, but I might use a bit of glue as well. As for the removable baffle, those little triangles in the cabinet are just plywood so that the screws will hold. I only had a few small clamps available, so I used screws with the first 3/4" unthreaded (along with glue along all the edges) to hold the cabinet together, and boy did it tighten up nice. When I cut the holes in the front baffle you can't even see where the two pieces were glued!

So as for holding the drivers in place, I think I will go with small blocks of plywood on the back, unless someone can give me a good reason not to. Thanks.


-Tyler

[cjd]

So, those are the wrong RS225's... they're not compatible.

Can't verify as Mark's page is coming up blank to me right now, but I'm 99% sure.

C

[speedle]

Oh man, that'll ruin your day. I believe you're right, it's the shielded ones Gir needs. Aren't those unshielded ones 4 ohms instead of 8 as well?

Go here:

http://web.archive.org/web/20060207200108/206.13.113.199/ncdiyaudio/mark/RS225_RS28A_updates/dayton_reference_rs225.htm

[Exocer]

Sorry to hear about the drivers

On another note, for surround duty would you guys recommend these Rs225 MT's over ported Modula MTs if near wall placement is important?

No hijack intended ops:

[Gir]

Woah, I definitely ordered the unshielded ones... Parts Express is getting a nasty call in a few minutes...

[EDIT]
I just checked the box, and they say RS225-4. Besides, doesn't the shielded one have essentially a big metal ring on the outside? The I have is just a rubber cover. I'm about 98% sure that it's the unshielded one (I'll give ya that 1% on me)

[Exocer]

Gir, I was also wondering if you are intentionally locating the tweeters in the upper right portion of the cabinets? Usually I see speakers with offset tweeters mirror each other, so the offset locates the tweeters inward towards each other.

[Gir]

Gir, I was also wondering if you are intentionally locating the tweeters in the upper right portion of the cabinets? Usually I see speakers with offset tweeters mirror each other, so the offset locates the tweeters inward towards each other.

I wasn't quite sure which way to do it, so I just stuck with offsetting them both on the same side, which I would think acoustically it wouldn't change much if they were mirrored or not, but I kind of like the look. Anyone know if this will be a problem?

[Exocer]

Yeah, I sorta like the look as well. For surrounds I would totally do that.

[Gir]

Sorry to hear about the drivers

On another note, for surround duty would you guys recommend these Rs225 MT's over ported Modula MTs if near wall placement is important?

No hijack intended ops:

For near wall placement the Modula MTs are probably better since there is a XO design just for that. This is what my roomate and I decided on. We're using my speakers as mains, and I'm also building a Sonosub and buying all the audio equipment. My roommate is building the center channel (still deciding on that one) and Modula MTs for the surrounds, and he's also buying the 37" HDTV. We're happy campers :T

[cjd]

Woah, I definitely ordered the unshielded ones... Parts Express is getting a nasty call in a few minutes...

[EDIT]
I just checked the box, and they say RS225-4. Besides, doesn't the shielded one have essentially a big metal ring on the outside? The I have is just a rubber cover. I'm about 98% sure that it's the unshielded one (I'll give ya that 1% on me)

Yes. You got what you ordered.

You ordered the wrong RS225's.

You need the shielded ones. More critical is the difference in impedance: the unshielded are 4ohm, the shielded 8ohm.

C

[Gir]

Wait, I thought he used the unshielded version? He mentions nothing of the shielded version. He just says the RS225 and the unshielded version of the RS28a. Was I supposed to assume that he meant shielded by default?

[Brian Bunge]

Nope, he used the shielded ones. IIRC, the unshielded ones weren't even available when he first designed these. I'd call PE on Monday and just tell them you ordered the wrong drivers. They'll probably swap them out for you without any problems.

[Mark K]

Brian is right. I guess I should go back and make that explicit. At the time I designed it, there was no unshielded version. I don't recommend using the unshielded ones. PE will try to make it right, though you might be out a bit of shipping...maybe. PE is pretty good about this.

[Gir]

Sorry about the angry rant Mark, it's not your fault, I probably should have read some more. It's actually not that big of a deal since I have to go back to school and can't finish the speakers until next weekend anyways. Besides, the other speakers are a few bucks cheaper, so that basically cancels the cost of shipping, so no harm done.

Cheers,
Tyler

[Gir]

So I called Parts Express this morning, and managed to convince them to pay for shipping one way! So now they're going to ship the shielded ones to me and all I pay overall is $4 more. I'm back at school now, so no updates until (hopefully) this weekend.

[ssabripo]

These are great surrounds.Don't hesitate.They put out tons of sound with very little effort.This is the thin version(only 8" deep).

Way to go Mark !

KG...you got any more updated pics on your setup? :T

[JonP]

In my opinion, the best solution is just to use appropriate wood/drywall screws with wide threads. My experience with T-nuts is that for a flange like that, they can mangle the MDF a bit because they are so close to the edge, hurricane nuts are prone to spinning, hurricane nuts plus epoxy might work. I would put nice metal threaded fasteners on the joint between your cabinet and removeable baffle, but just screw the drivers directly to the baffle.

I've used the glue a small piece of plywood method before. I did a 45 deg chamfer in the back of the baffle for less obstruction on a little B3N speaker, it really needed it. That left very little thickness left where the screw was going thru. Made little 45 deg corner blocks that fit right in with the chamfer, epoxied them down. Lots of "meat" for the screws to go thru. I just finished a pair of Modula MT's, and back chamfered them too.. with the doubled baffle and the big magnet, they were "down in the hole" as much as the B3N. Though, there was enough thickness left at the screw holes that I didn't add extra anchor points. Box was made out of Baltic Birch, not MDF, I might not have felt as comfortable otherwise. Another thing, the RS drivers have 6 holes not 4.

I've used hurricane nuts, epoxied in, with good success on a 15" Quatro sub. (in 3/4" MDF) I see some people really pan them, but I think it's probably drilling the hole a bit large and then they're easy to twist loose. I measured with calipers part way down (they taper a bit), picked the closest drill size, and wet the back surface and a bit of the shank with epoxy before pulling them tight with the screw and a stack of washers. That way you don't have the driver in there if one spins, and you can hold it from the back if need be to get it snug and let the epoxy set up. Be VERY careful to not end up with some epoxy in the threads...

[Gir]

I just finished up the first speaker (minus the woofer), and I tested the tweeter and it sounds great! Nice and crisp sound. I'm really hoping the woofers come today, otherwise I have to wait until next weekend >_< I'll post pics later and let you know if the woofers come.

[Gir]

Sorry for the lack of updating, I've had limited acces to the internet. That being said...

THEY WORK!

The woofers came yesterday, so I actually hopped on a bus to head home for the night just to finish them, then took a bus this morning back to college :T

Before I go into listening impressions, I need to mention that I won't have my audio equipment until the summer when I start my job. So at the moment I'm using a (crappy) receiver from1976 with a laptop (napster) and an old school record player (which is actually pretty good) hooked up. But hey, even with the crappy equipment the speakers still sound great! They put out a nice "big" sound, but right now, hopefully due to the equipment, the imaging isn't too good. It's okay, but I'm sure it'll sound a lot better once I get some good equipment.

And on that note, what do you guys think of the Yamaha RX-V659 with a Denon 3910 hooked up to it? I plan on getting the receiver new and the player used. If you guys have any other suggestions on receivers or players feel free to let me know. I am on a smaller budget though.


As a final note, thanks for all the help guys! You've been great!


-Tyler