My RS180 MTM Design

[coniacvsop]

Re: My RS180 MTM Design

Mike. What diameter and length port did you use? Firing Down? Rear? Forward? From what I understand, these are incredible sounding speakers for the price. They will be in equal HT and music duties. I just really wanted to build soemthing that would satisfy me for a while to come without the itch to upgrade in the near future. Any advice would be appreciated. Thanks

[coniacvsop]

Re: My RS180 MTM Design

Yes Jeff. It seems like there have been several versions of this MTM in a larger bass extended tower design. Thanks for the response, your crossover looks like a relief compared to the other versions I've seen. I'm still a newbie, in the process of getting my feet wet with the vented Tri Trix design for my father. I wanted to build some towers that would sound excellent and that I would be happy with for some time to come....your design seems to fit that bill pretty well. I have a Dayton Titanic sub that I built, so I wanted my my mains to play with some authority down to at least 60HZ where I would cross them over. Thanks again.

[mike price]

Re: My RS180 MTM Design

I built mine in larger enclosures , I believe around 1.6 cubic feet , kept the baffle width and driver layout the same , and they sound incredible.

[Jeff B.]

Re: My RS180 MTM Design

I'm not sure how much action this thread is still getting but I was wondering if this crossover would be kosher to use with the extended bass towers documented in other threads? I was looking at building the 1.7cu ft Nat P's, but stumbled across Jeff's new design. Any help would be appreciated. Thanks

I guess I don't read many threads anymore, so I'm not sure I know exactly what you are referring to. Are you talking about building my speaker in a larger tower version to extend the bass? If so, it should work well if you keep the baffle width about the same and get the tweeter to the right listening height. (You might want to weight the bottom fairly well to avoid any top-heavy issues.)

[coniacvsop]

Re: My RS180 MTM Design

I'm not sure how much action this thread is still getting but I was wondering if this crossover would be kosher to use with the extended bass towers documented in other threads? I was looking at building the 1.7cu ft Nat P's, but stumbled across Jeff's new design. Any help would be appreciated. Thanks

[cjd]

Re: My RS180 MTM Design

That's what I thought too based on the published curves. However, someone who measured both under the same conditions appearred to contradict this by showing them to be very close in response. Did you measure them yourself and establish that they would not interchange? I would have, but I didn't think to do it when I had both here at the same time.

Jeff

I honestly don't remember if I had one on hand along the way or not but I think I did not. :o I think I did some fiddling with someone elses measured data, not my own. The MTM I put together (RS150) was definitely using PE's published FRD/ZMA from back when they offered those, along with modeled diffraction, etc (though the specifics of the process, the exact diffraction and baffle step, were backed up with measured data on the plain RS28A as well as the 27TDFC so I have a high level of confidence in its accuracy.) It does come down to the particulars of the crossover though, and I never did look into why. The lower the crossover, and the steeper the slopes, the more trouble.

C

[Jeff B.]

Re: My RS180 MTM Design

Back when I worked up designs for the RS28A and RS28AS versions, I found that they were not interchangeable. YMMV.

C

That's what I thought too based on the published curves. However, someone who measured both under the same conditions appearred to contradict this by showing them to be very close in response. Did you measure them yourself and establish that they would not interchange? I would have, but I didn't think to do it when I had both here at the same time.

Jeff

[cjd]

Re: My RS180 MTM Design

As I pointed out in other posts in this thread - my design was with the RS28AS.

Back when I worked up designs for the RS28A and RS28AS versions, I found that they were not interchangeable. YMMV.

C

[Jeff B.]

Re: My RS180 MTM Design

sorry i am late to the party, but is there a kit for this?

Just what I posted at the top of the thread.

[smokarz]

Re: My RS180 MTM Design

sorry i am late to the party, but is there a kit for this?

[Jeff B.]

Re: My RS180 MTM Design

I am skipping the bi-amp stuff above...Jeff would this passive crossover work for a single RS-180-4?

The lowpass and highpass sections will work fine, but you will need to pad down the tweeter about 3dB.

[billschulte]

Re: My RS180 MTM Design

as an uninformed observer of this site, I have been following this section closely. I would like to do a bi-amp of a single Dayton RS180(8 or 4) and found Jeff Bagby's Denhams response shaping network. Does anyone have a network like this worked up for a single RS 180?

I am skipping the bi-amp stuff above...Jeff would this passive crossover work for a single RS-180-4?

[czag]

Re: My RS180 MTM Design

As I pointed out in other posts in this thread - my design was with the RS28AS. I have never built it, or adjusted it for any other tweeters, so you're not picking apart my design. Substituting tweeters is completely up to the end user. A lot of that gets discussed here too. Adustments are easy to make though, and shouldn't be a problem for anyone wanting to go down that road.

Understood. Members are trying whatever they can to make this design work for them with a different RS tweeter because you developed such a simple but effective xover. I'm glad you decided to share it and your xover design programs, I am sure I wouldn't be nearly this deep into speaker building if you had not developed PCD.

Chris

[Jeff B.]

Re: My RS180 MTM Design

That is what John's test showed also, this model was made from a newer unit with 91db sensitivity for the RS28A. These differences could very well be attributed to Dayton's unit to unit variability. There was about 1.5db difference in sensitivity between the batch of 5 RS28F that John tested for me. I used the one with about 91.5 sensitivity for the RS28F since that seemed to be about the average for the 5 units I have.

When I modeled it the extra top end rise seemed to come from the xover being applied.



I do not want to come off as if I am picking you design apart, it is by all accounts a great design. I just wanted to point out that these 2 tweeters may not be drop in replacements in every design due to the differences in top end and unit to unit consistency. This was just something I noticed when working on my own project with a similar tweeter xover topology , but with different woofers.

Chris

As I pointed out in other posts in this thread - my design was with the RS28AS. I have never built it, or adjusted it for any other tweeters, so you're not picking apart my design. Substituting tweeters is completely up to the end user. A lot of that gets discussed here too. Adustments are easy to make though, and shouldn't be a problem for anyone wanting to go down that road.

[czag]

Re: My RS180 MTM Design

The current RS28a's are almost 2dB more sensitive than early versions. Plots I have seen of current tweeters (A and F versions) overlay each other almost perfectly except for the response above 15kHz. By the way, I don't get quite that much rise at the top of my RS28F.

That is what John's test showed also, this model was made from a newer unit with 91db sensitivity for the RS28A. These differences could very well be attributed to Dayton's unit to unit variability. There was about 1.5db difference in sensitivity between the batch of 5 RS28F that John tested for me. I used the one with about 91.5 sensitivity for the RS28F since that seemed to be about the average for the 5 units I have.

When I modeled it the extra top end rise seemed to come from the xover being applied.



I do not want to come off as if I am picking you design apart, it is by all accounts a great design. I just wanted to point out that these 2 tweeters may not be drop in replacements in every design due to the differences in top end and unit to unit consistency. This was just something I noticed when working on my own project with a similar tweeter xover topology , but with different woofers.

Chris