Creating a possible 5 speaker system...

[Sonnie]

Brian... got a few questions for you.

I really like the design behind your RAD Pulsar 9.1's. Do you think these would be good for a dedicated HT room? If so... I have these questions?

First, can you finish these is a satin black?

Second, can you create a matching horizontal center and will it work if you did an 8.1... with the tweeter in the center and four of the same drivers on each side of the tweeter? I like the idea of having a wide center channel... 44" would be perfect.

Third, can you do a bipole design for the rears... realizing these would obviously have less drivers, would they be capable of handling down to 80hz well? I'm think max two of the 3" drivers on each side (or front and back). I would not want these very tall... maybe 14-16" max. I like the width being narrow because as they would be wall mounted it would mean a very shallow depth from wall to front with them being mounted on one side. I'd also need recessed speaker terminals on that wall side.

Finally, the power rating concerns me somewhat. I running the Earthquake Cinenova Grande. 300 wpc into 8ohms and 600 into 4ohms. This makes me wonder if these are gonna give me that midbass impact I'm looking for from 80-200hz. It might mean I really need a more robust design, but I do like the multiple array. It might be that we could design something similar and use a couple of 6 or7's at the bottom and reduce the 3's to 6 drivers. For the center use a 6 or 7 on each outer end, 3 x 3's on each side of the center tweeter. But you are the designer so I'll let you tell me what you think.

[Brian Bunge]

Sonnie,

I think we can probably work something out here. I'm not sure if the Pulsars will meet your needs or not. First I'd need to know what size room you have and if it's sealed off from the rest of the house. A satin black finish would be possible also, although a bit more work than a veneered finish.

Also, the Pulsars in their current form are ported but they really sound better sealed and crossed over to a sub. I've currently got the ones from the website in my bedroom and have the ports plugged. They don't extend as low, but they sound better. Depending on the size of your room I think you might be better off with a similar design but using larger drivers. Also, the Pulsars have pretty good efficiency for their small driver size so they're really meant to be paired with moderately powered receivers and amps. The little 3" drivers don't have a lot of excursion so multiples were used to keep efficiency up and keep the excursion per driver down. I think larger drivers in an array could possibly be a better option for you. I just want to make sure that with big subs that the speakers aren't the limiting factor in the system if at all possible.

I think an array of the Dayton 5" or 6" drivers would be an excellent choice. They could be an MTMWWWW for the towers and a WWMTMWW for the center. I've never designed a dipole surround so that'd be a new undertaking, but not impossible.

We'll definitely work something out though! Let me know what you think of what I've posted and we'll go from there.

[Sonnie]

Your idea sounds good to me... I like the array sequence. On the surrounds I want a bipole wiring scheme which is supposedly better for my setup.

A satin black veneer is okay if you can find it. I just don't want anything with a high gloss finish and I want it to be either black or a very dark gray.

I want to keep the center width as narrow as possible... well actually it would be the height since it will lay horizontally. I don't have much room to clear my screen from the top of cabinet. I'll double check but I believe about 8" is all the room I have to work with before I'd start to block my screen trim. The RM30's are 7" wide (high) and I have 1/2" rubber feet underneath them. They are just about perfect in size.

My room size is 11.5 x 19.5 x 8... about 1800 cubic feet.

[Brian Bunge]

Sonnie,

It wouldn't be too tough to veneer the cabinet in oak, dye it black and finish it with a satin polyurethane. It would actually be less trouble than a painted finish.

The speaker I have in mind would use 6 of the Dayton 6" woofers, which have an outer frame diameter of 5 15/16". With only a 1/2" roundover on the cabinet edges I could get away with a 7" wide cabinet. I think a 44" tall/wide cabinet will still work fine although the center may need to be a little wider if you want the cabinet built with ports on the front.

As far as bipole surrounds are concerned, I'll start doing some homework on those and see what I can come up with.

Also, your room really isn't all that large, so the current Pulsars might be adequate, but I think the speaker I'm proposing would work better for you.

[Sonnie]

Yeah... the dyed oak is fine. I'm really not that particular about the type of material finish as I would be the color and sheen. It's usually dark in there anyway... just as long I don't get glare. You figure that wide and probably fairly deep of a center right beneath the screen could be problematic if glossy. So a dyed oak with satin poly sounds like it should work fine.

I don't mind the speakers being taller or in the case of the center, wider for ports or whatever is necessary. I can get the width of my cabinet and as long as we stay within that we should be fine there too.

I think I agree on the larger drivers. I would really rather have more than adequate in case I increase the size of my room one day. You never can tell about me. I've threatened building a bigger room several times.

[Brian Bunge]

Sonnie,

Preliminary cabinet dimensions look like they'd be around 44"H x 7"W x 18"D. This should give you pretty flat response in room down to 40Hz or so. We could get a little more extension, but the cabinet would have to be even bigger in order to do so. And I don't think the added extension is worth the hit you'd take in output. So I think shooting for flat in room response to around 40Hz would be the way to go.

Also, another option is to go for larger L/R speakers and keep the center smaller. The 7" width limit really makes it difficult to get the appropriate internal volume. You end up with an extremely deep cabinet for a given volume. So if you wanted towers with better extension than the center we could go with something larger width wise for them and still keep the center to the 7" width limit.

[Sonnie]

I'm good with 40hz... this gets me one octave below my crossover.


I may not be following you on the center. 18" is okay on the depth of the center if you are thinking that I might not want it that deep.


I measured the RM30's... not sure where I got 7" from... they are 8" wide (high on center) x 48" high (wide on center) by 21" deep.

My cabinet top is 18" deep x 69" wide.

The RM30 center hangs off the back of the cabinet 3" or so. I've got the front grill even with the front of the cabinet.


We could go up to 8" on the width, but I do like 18" deep better than 21". 44" to 48" on height is good... I like 44" better but 48" is okay if we need it for the L/R. On the center I don't mind up to about 60" on the width if that's what we need for some reason.

[Brian Bunge]

Hummm....give me a full 8.25" to work with width wise and things get very interesting! Assuming that width, I can do a WWMTMWW for the center and go with quad Dayton RS 7's for the woofers and still use the RS 6's for the mids. This would be a step up and gives us similar cabinet depth while increasing height to around 48". I really like this idea as the 7's are a step up from the 6's and I think would serve you even better.

[Sonnie]

Sounds good to me. I can stand 8.25" okay. I may have to lay the center down on the cabinet with not rubber feet, but I can place a piece of felt between the speaker and cabinet as protection.

I like the idea of the 7's for W's and 6's for M's.

[Brian Bunge]

Sonnie,

A couple of quick questions:

How tall/wide can you go? Is 60" too high/wide? If so, could 50" work for you? Also, how important is low end extension? The 60"H gives better extension but only when running full range. With an 80Hz crossover it's a moot point. Either way, these two heights still allow for a 8.25"W x 18"D cabinet. It's just a matter of low end extension.

One other thing to think about also. For the front L/R speakers, if we make the towers into WWWMTMW so that only 3 of the woofers are under the MTM array then tweeter height can be lower and in closer proximity to the tweeter height of your center.

[Sonnie]

I think 60" is probably a little on the tall side for the L/R... 50" will probably be okay. I'll definitely be using a crossover from 60-80hz... probably 80hz. What kind of extension would be there with the 50" height?

I don't have a problem with the array... whatever will sound best. What would be the crossover of the midrange/tweeter?

If you can get the tweeter on the center speaker on the top half of the speaker when the speaker is placed horizontally without it effecting anything negatively, that would be good. That cabinet is a little lower than ear level when seated.

Like you did with this one...



How would two tweeters stacked on top of each other in the center speaker work out?

[Brian Bunge]

Sonnie,

With the 50" height, you'd have a natural anechoic F3 around 48Hz, but it'll get some decent boost in room and should be flat to just below 40Hz. With the 60" height it'll have a natural anechoic F3 around 35Hz, but drops off sharply below that. If you were using them for 2 channel stereo and weren't going to have high output requirements (and weren't using some serious subwoofage) then the lower extension of the 60" hight cabinet might be what I'd go for. Since you're going to use subs with something like a 60-80Hz crossover point then I think you'd be fine with the 50" high cabinet. Also, the smaller cabinet gives you a little better power handling.

The tweeter would definitely be offset towards the top of the center channel. This is mainly so that the woofers can be pushed closer together and give better off axis response. This helps to alleviate the comb filtering associated with typical MTM style center channels. Also, a separate crossover would be designed specifically for the center channel as well as for the towers. Oh, and the crossover would probably be somewhere in the 1800Hz-2100Hz range.

[Sonnie]

F3 of 48Hz sounds fine to me... 50" will work... I like that better anyway.

[Brian Bunge]

OK, so where do you go from here? Next up for me is to start building prototypes and start taking measurements for crossover design. But I want to wait until we're sure this is a go.

[Sonnie]

I guess price is next... not sure if you wanna do this behind the scenes or publicly... it does not matter to me one way or another. I kinda need to know where I'm gonna be financially... in the welfare line or hangin' out here in the forum... heehee.

[garycase2001]

Curiosity got to me while reading this thread ...

(1) Did this sytem get built ??

(2) ... and if so, question for Sonnie: How does it sound ??

[Sonnie]

Nope... funds got low and I ended up not being able to go this route for now. Currently I'm using a very inexpensive JBL Northridge setup that actually sounds pretty good.

[garycase2001]

Ahh yes, that old bugaboo called $$$ ==> If it wasn't for that I'd have bought a JBL Paragon about 40 years ago, when I first fell in love with it. THAT was a speaker system !!