Idea for a 3-way.......

[Ray Tremblay]

New idea. Please check out the new thread:

http://techtalk.parts-express.com/sh...38#post1515738






Vifa XT25 tweet / Vifa XG18 mid / Dayton RS180 midbass-woofer

crossed somewhere in the 500Hz/2.5Khz neighborhood

I love the low end of the RS180's in a large vented enclosure, and their price makes them a no brainer. I've always wanted to try out the XT25, but it won't work in a 2-way with the RS180. So when I read about the XG18 on John Krutke's site: "It has extremely low upper midrange harmonic distortion, among the best in the group........ Would make a great midrange driver........." I thought it might be a good choice for a mid. Then in the "Archives" of John Krutke's site, I saw the Vifa XG18 / XT25 2.5-way TMM design. John said, "This design had the most incredible midrange and high end I've heard. Unfortunately, I've come to the conclusion that my 2-way XG18/27TDFC MTM design sounds better." it furthered my guess that the XG18 would be a spectacular midrange.

What do you guys think? Do you see any flaws in this choice of drivers?

[gowa]

Check out Lou's offering.
http://www.lonesaguaro.com/speakers/XG12/XG12.htm

[neildavis]

What do you guys think? Do you see any flaws in this choice of drivers?

Can you still get the XG18? The Tymphany pages suggest that the only survivor in this series is the XT18WO09.

The smaller TG9 drivers have gotten very good reviews and may be a good replacement.

[jbruner]

I can't figure out why anyone would choose the RS180 over the RS225 for the bottom of a three-way unless it's a cabinet size issue.

[Pete Schumacher ®]

Vifa XT25 tweet / Vifa XG18 mid / Dayton RS180 midbass-woofer

crossed somewhere in the 500Hz/2.5Khz neighborhood

I love the low end of the RS180's in a large vented enclosure, and their price makes them a no brainer. I've always wanted to try out the XT25, but it won't work in a 2-way with the RS180. So when I read about the XG18 on John Krutke's site: "It has extremely low upper midrange harmonic distortion, among the best in the group........ Would make a great midrange driver........." I thought it might be a good choice for a mid. Then in the "Archives" of John Krutke's site, I saw the Vifa XG18 / XT25 2.5-way TMM design. John said, "This design had the most incredible midrange and high end I've heard. Unfortunately, I've come to the conclusion that my 2-way XG18/27TDFC MTM design sounds better." it furthered my guess that the XG18 would be a spectacular midrange.

What do you guys think? Do you see any flaws in this choice of drivers?

Load up with a larger bass driver.

Go for at least a 10" RS, or RSS, maybe even the 12" RSS. Even a pair of RS225 wouldn't be bad. But a single RS180, while not a bad driver, just won't have the stuff to keep up with the mid at higher volumes. It's all about displacement down low, and you need surface area or excursion, and the RS180 has neither, unless you run at least two of them, maybe even 4.

[jkim]

I can't figure out why anyone would choose the RS180 over the RS225 for the bottom of a three-way unless it's a cabinet size issue.

Yes, it is the cabinet size. RS225 should be better than RS180 for a bass/midbass duty. Only needs a larger box.

[jkim]

What do you guys think? Do you see any flaws in this choice of drivers?

Check out Roman's Dionysus:

http://www.rjbaudio.com/Dionysus/dionysus.html

[Ray Tremblay]

I can't figure out why anyone would choose the RS180 over the RS225 for the bottom of a three-way unless it's a cabinet size issue.

It's the desired appearance which dictates the cabinet size. I like the appearance of a tall slender cabinet with a lot of small bass drivers with a mid of equal size. I was thinking four RS180's per cabinet. These are just for music. Eight RS180's total should be enough to never desire a sub.

[Ray Tremblay]

Can you still get the XG18?

I come across them for sale (new) on the boards pretty often. Usually car audio guys that bought the and then decided to go in a different direction.

[Pete Schumacher ®]

It's the desired appearance which dictates the cabinet size. I like the appearance of a tall slender cabinet with a lot of small bass drivers with a mid of equal size. I was thinking four RS180's per cabinet. These are just for music. Eight RS180's total should be enough to never desire a sub.

I like the look too.





I spaced these DA175 out a bit differently than most would, but the look is reminiscent of another system I designed, but built by someone else.



This system design was reviewed at Audioholics and the results were pretty good.

Rudy Jakubin built a 4-woofer 3-way using the RS180, the RS52 mid and a dayton Neo tweeter. I know he likes the bass performance. The 4-woofer 3-way I did uses the same mid and tweet, but 4 DA175 woofers in a vented cabinet tuned to 24Hz. The bass extension is pretty amazing, though peak SPL is limited. 4 RS180 would provide a bit more peak SPL and lower distortion than the DA175.

The biggest problem with using 4 RS180 with the XG18 is that the XG would not have the sensitivity to keep up with the quartet of RS180. The DA175 on the other hand is a lower sensitivity driver, and a quartet of them would match nicely to the level of the XG18.

[turn2]

I like the appearance of a tall slender cabinet with a lot of small bass drivers with a mid of equal size. I was thinking four RS180's per cabinet. These are just for music. Eight RS180's total should be enough to never desire a sub.

Yeah, sounds like a great idea!

[Ray Tremblay]

The biggest problem with using 4 RS180 with the XG18 is that the XG would not have the sensitivity to keep up with the quartet of RS180. The DA175 on the other hand is a lower sensitivity driver, and a quartet of them would match nicely to the level of the XG18.

I figured I could adjust the level of the RS180's (bring it down) in relation to the XG18 and XT25 in the crossover. I just want to have alot of low frequency dynamic range "on tap" to cover any instances of low frequency blasts during a song. This is my issue currently with only two RS180's per tower. I can't get the music really loud without the RS180's bottoming out during some parts of songs.

[ap]

Unless you bi-amp & drive the woofers separate you wont be able to reduce the level of the woofers.
Why not just use 2 x dayton RS225? It would work out (slightly) cheaper & give you an easier xover., and probably a better match in level.
Andrew.

[Ray Tremblay]

Unless you bi-amp & drive the woofers separate you wont be able to reduce the level of the woofers.
Why not just use 2 x dayton RS225? It would work out (slightly) cheaper & give you an easier xover., and probably a better match in level.
Andrew.

That's definitely an option, and honestly, probably the only other direction I would go in, but I really want to do a tower with 4 RS180's per side. I really like the look of a tall slender tower with many drivers that are all the same size (besides the tweeter of course). I wanted to do a MTWWWW, but if I have to do a MTMWWWW to balance it out a little better, I'm not opposed to that at all.

If I build this, I really can't see myself wanting another speaker for a very long time. I had a pair of Polk RT55's (TWW) for about 7 years. I really liked the way the midrange sounded on those, but that was about it. I didn't really like anything else about them. The midbass and low end was GARBAGE. The midbass and low end of the RS180's ANNIHILATE the Polk woofers! And the tweets just didn't have that very detailed metal tweeter sound that I like. Not that I'm assuming the XT25's will, but I want to see how they sound.

[Pete Schumacher ®]

That's definitely an option, and honestly, probably the only other direction I would go in, but I really want to do a tower with 4 RS180's per side. I really like the look of a tall slender tower with many drivers that are all the same size (besides the tweeter of course). I wanted to do a MTWWWW, but if I have to do a MTMWWWW to balance it out a little better, I'm not opposed to that at all.

If I build this, I really can't see myself wanting another speaker for a very long time. I had a pair of Polk RT55's (TWW) for about 7 years. I really liked the way the midrange sounded on those, but that was about it. I didn't really like anything else about them. The midbass and low end was GARBAGE. The midbass and low end of the RS180's ANNIHILATE the Polk woofers! And the tweets just didn't have that very detailed metal tweeter sound that I like. Not that I'm assuming the XT25's will, but I want to see how they sound.

A good sub.

If you simply drive your mains with an HT receiver set to small speaker mode and add a sub for the low end, you'd be much better off than what even 4 RS180s could do for those dynamics you're looking for. It's the 1st octave stuff that's the toughest to deal with, even with a quartet of RS180s.

But your suggested MTM top end using the XG would be an adequate match for the RS180 array from a sensitivity standpoint. And with the MTM section really needing to be on axis at the listening position, you may want to do a WWMTMWW. Otherwise, the tweeter may be quite a bit above the listening position, which is not optimal for an MTM. The XT25 really needs to be crossed at 2500Hz or higher to avoid distortion, and for a 7" woofer, CTC at 2500Hz becomes somewhat an issue, narrowing directivity.

[Ray Tremblay]

A good sub.

If you simply drive your mains with an HT receiver set to small speaker mode and add a sub for the low end, you'd be much better off than what even 4 RS180s could do for those dynamics you're looking for. It's the 1st octave stuff that's the toughest to deal with, even with a quartet of RS180s.

Using a sub defeats the purpose of this design. I want a pair of speakers that have a decent amount of low end and don't require a sub. Two RS180's per side seems to work well. I just need a little more volume out of them. I figured doubling up on the RS180's would be adequate.

But your suggested MTM top end using the XG would be an adequate match for the RS180 array from a sensitivity standpoint. And with the MTM section really needing to be on axis at the listening position, you may want to do a WWMTMWW. Otherwise, the tweeter may be quite a bit above the listening position, which is not optimal for an MTM.

What is the ideal height for the tweeters? Ear level from the listening position?

[Ray Tremblay]

The XT25 really needs to be crossed at 2500Hz or higher to avoid distortion, and for a 7" woofer, CTC at 2500Hz becomes somewhat an issue, narrowing directivity.

I haven't quite gotten a grasp on center to center spacing of mids and tweeters, and it's relationship to the crossover frequency. If someone would, please explain so that a new guy can understand.

[Ray Tremblay]

What if I were to run three 4ohm RS180's, one XT25, and one XG18 per side in a MTWWW or a TMWWW configuration? This could get the listening position on axis with the tweeter level.

If I run three 4ohm RS180's in series to reach a 12ohm load from the woofer array, would this work to get the sensitivity between the woofers and the XG18 mid a little more consistent? How hard would it be to get a crossover to work with the 12ohm load?

[ap]

I like the idea of the 3 x 4ohm in series, keeping in mind you wont really hit 12ohm - but your sensitivity will stay the same at 91db, if you take off about 3db for baffle step you should be right on target for about 88db - this should be fine for the XG18.
I suggest you get a copy of the PCD (Passive Crossover Designer)
from http://www.pvconsultants.com/audio/frdgroup.htm
& start playing with numbers.

As an alternative, the dual woofer mtm 3way looks good:

http://www.customanalogue.com/elsino...nore_index.htm

Also it might be worth trying to track down Pete Schumakers design using the DA175 (4 of them) in a 3way tower, sorry i dont have a link but you should be able to track him down on a forum, somewhere.
Andrew.

[jkim]

Ray,

If MTWWWW with XG18 and RS180 is what you want, there is no reason you can't lower the sensitivity of the woofers using a resistor. You only need to use a resistor of high power rating (or mutiple resistors in parallel to increase power handling).

You don't have to worry about the relationship between amp and woofers. A resistor is simply part of the filter. There's nothing wrong in this approach as long as you obtain your desired bass curve and impedance.

There are a few different ways to do this: a series resistor before the xover, before the woofers, or a shunt resistor after the xover. Since you're going to use four RS180S-8's in series & parallel wiring, you can use the third option---I prefer this approach for some reasons.

Below is my simulation that shows how this works.







A target xover point is 400 Hz LR2. The simulation uses the RS180's IB measurement. You will need to use a properly modeled response for a more accurate result. Anyway, a point is that you can lower the woofers' sensitivity this way with reasonably lowered impedance. If you consider baffle step loss and filler midrange's gain from other drivers, this will work nicely for the 3-way.

-jAy