Is there interest in an RS150 dipole?

[Undefinition]

I'll let you all in on a little secret... I have been planning another entry into the MTMW open-baffle catalog.

Not that I really need to. But I think that some people might have been a bit incredulous of the Sunflowers; that there was an expectation that if someone did an dipole or OB with the Dayton RS, that the mids would be the RS150 or larger. Whereas, I went a little small on the Sunflowers and used the RS125. According to the Andy G school of thought, dual 4" mids is pretty spot-on for a dipole MTMW... and I have no regrets about the design or its driver choices. IN fact, out of all the DIY projects I've done, that is the one I always "hook back up" because it just sounds right to my ears.

HOWEVER, a dipole with the RS150 certainly is doable. But I've been holding off for a few reasons. One, my house is small and these sort of floorstanders do take up some room (however, the plan is to get a bigger house in the next few months). Two, I don't have any problems with the Sunflowers and there's nothing I feel needs to be "upgraded." And three, well, unless you've been averting your eyes from every media venue, the economy is down and it seems that small, inexpensive projects are in (and I have several of those already, and more lined up).

But I'm putting out a depth charge to find out if anyone would be interested in an OB using the Dayton RS150 (actually, it would be the RS150-4, to be more precise). I'd still try to keep it budget friendly. The Sunflowers can be built for under $450. These shouldn't cost too much more... hopefully not much more than the difference in price between the RS125 and the RS150.

Speak your mind.

P.S. forgot to add...
tweeter choice will almost definitely be the BG Neo3 PDR. The woofer at this point would probably be the RS225, because it's got amazing power handling for a single driver, and in a 1.5 cu ft box gets good enough extension for any of the music I listen to (vented, that is).

It's not to say that I couldn't go sealed, but I just crave 30 Hz extension ('specially in a floorstander), and that's not really something you ask of a sealed woofer, unless it has some sort of active EQ.

[ttan98]

A suggestion, rather another MTM at the top maybe you may like to try just one high quality mid-range driver and equally good tweeter, similar arrangement as Dan.You may find this combo very different to your MTM config. and give both config. a direct comparison.

I am trying this combo, using either PHL1220 or a cheaper Eminence Beta 8a and a ribbon tweeter, eg Aurum Cantus, G2 or Hi-Vi 8. For the bass I am in 2 mind, a dual 12" open baffle house in a H-frame or a reflex bass similar to Dan.

Cheers.

[fjhuerta]

I like the idea of an MTM, if only because of the added sensitivity.

But while we are at it, why not add a second RS225, and make the speaker a real powerhouse... oh, wait. This is supposed to be a small speaker.

[brianpowers27]

A suggestion, rather another MTM at the top maybe you may like to try just one high quality mid-range driver and equally good tweeter, similar arrangement as Dan.You may find this combo very different to your MTM config. and give both config. a direct comparison.

This is an interesting comparison that I don't think I have ever seen directly. The single driver vs MTM would increase the horiztonal off access response in the upper midrange response near the xo range. The reflections are likely to be in much better phase, causing less cancellation.

[AJINFLA]

It's not to say that I couldn't go sealed, but I just crave 30 Hz extension ('specially in a floorstander), and that's not really something you ask of a sealed woofer, unless it has some sort of active EQ.

Hi Paul,

Out of curiosity, have you ever measured the in-room response of your vented system? It will of course vary per mic position.
Here is a 1/6th octave shot at about where my head is, seated in my listening chair, showing the extension of the non-vented system you heard at Lexington (undoctored ).



cheers,

AJ

[Undefinition]

Out of curiosity, have you ever measured the in-room response of your vented system? It will of course vary per mic position.

I have, but I didn't really know what to make of it, to be honest. Large-gated MLS is basically nonsense down there. Stepped sines actually looked reasonable... but I didn't know if I should trust it. Most of the time I just play sines at particular frequencies and walk around with an SPL meter to look for changes. That, and I just listen for what sounds good--I know, far from scientific.
But I'd like to know: what's a good method for getting reliable in-room measurements below 200 Hz (from listening position is fine)?

[Undefinition]

A suggestion, rather another MTM at the top maybe you may like to try just one high quality mid-range driver and equally good tweeter, similar arrangement as Dan.You may find this combo very different to your MTM config. and give both config. a direct comparison.

Hmm. Actually, I hadn't thought about that. I could certainly do a TMW with the RS180 as the mid. I have always been wary of just using a single small mid for a dipole, because it seems that Linkwitz's and Kreskovsky's designs all have a lot of "surface area" in the midrange. And I've heard "dipoles" that used a single small mid, and it's just not the same 3-dimensional soundstage.
... on the other hand, I heard Jeff B's design for Salk, and I've heard Dan N's prototype Basslines, and the results were quite beautiful sounding in both cases.

I also like this idea because it would make for an interesting comparison against the Sunflowers. I'll have to give this some more thought!

[ttan98]

Hmm. Actually, I hadn't thought about that. I could certainly do a TMW with the RS180 as the mid. I have always been wary of just using a single small mid for a dipole, because it seems that Linkwitz's and Kreskovsky's designs all have a lot of "surface area" in the midrange. And I've heard "dipoles" that used a single small mid, and it's just not the same 3-dimensional soundstage.
... on the other hand, I heard Jeff B's design for Salk, and I've heard Dan N's prototype Basslines, and the results were quite beautiful sounding in both cases.

I also like this idea because it would make for an interesting comparison against the Sunflowers. I'll have to give this some more thought!

I heard Eminence beta 8A is quite good at the same time quite cheap, $54 each. It is worthwhile of giving it a try because you have built so many MTM versions and know the sound quite well, so why another MTM. I don't think RS150 will be a real improvement over your existing sunflower, my guess it will just sound different at best a slight improvement over your existing systems. You need to make(after so many hours of time spent) another pair which sounds superior to your existing sunflowers or aether.

Cheers.

[pedroskova]

Given what you've already tried...instead of comparing Macintosh(sp?) to Roma apples...why not try a different approach, like a 10" midbass (AE comes to mind) with something that crosses low (like a BG neo8 ). The neo8 might surprise you with how well it does (in the real world) in the upper registers. This would allow a true apple to oranges, compare and contrast, test. I would bet on the AE/neo8 vs the RS180/neo3...at extra cost, of course.

[AJINFLA]

I have, but I didn't really know what to make of it, to be honest. Large-gated MLS is basically nonsense down there. Stepped sines actually looked reasonable... but I didn't know if I should trust it. Most of the time I just play sines at particular frequencies and walk around with an SPL meter to look for changes. That, and I just listen for what sounds good--I know, far from scientific.
But I'd like to know: what's a good method for getting reliable in-room measurements below 200 Hz (from listening position is fine)?

Hi Paul,

Gating is what you need when you want to remove the rooms influence. RTA will include the room. An SPL meter (like the infamous Ratshack) is woefully inadequate (unless your name is Woojay Sim :W).
The free version of ARTA should be on your download list.

cheers,

AJ

[fjhuerta]

Hi Paul,

Out of curiosity, have you ever measured the in-room response of your vented system? It will of course vary per mic position.
Here is a 1/6th octave shot at about where my head is, seated in my listening chair, showing the extension of the non-vented system you heard at Lexington (undoctored ).



cheers,

AJ

That's an amazing in room response... are you using room treatments? :E

[AJINFLA]

That's an amazing in room response... are you using room treatments? :E

I have a velvet elvis on the right wall.
I don't believe in room treatments. The design of the loudspeaker must make the room behave, not vice versa.

cheers,

AJ

[brianpowers27]

AJ,

Could you describe your measurement setup? (1/6 octave Smoothing?)

Large-gated MLS is basically nonsense down there. Stepped sines actually looked reasonable...

It seems like you would be better off using a different measurement technique.

MLS isn't going to account for the non-linear distortion in the system. Sines are going to be more accurate. If the sine length is varied the amoutn of room influence will change.


Taken from the arta manual....
Starting at P65 -- 5 Impulse Response Measurement
Sines:

"Notes: Swept-sine is an optimal excitation signal for fast measurement of an acoustical impulse
response without the averaging. It gives a better estimation than other excitation signals in acoustical
time-variant environments and in slightly nonlinear systems.
Swept-sine is not the good excitation signal if the environment generates a large level of the colored
or impulsive noise. It also gives a bad estimation in the system that has frequency sensitive automatic
gain control or automatic noise suppression. In those cases the periodic noise excitation gives a better
estimation."

MLS

The biggest problem with MLS signal is that some of MLS subsequences are correlated and they can
generate serious distortions when measuring the response of nonlinear systems. That is way;
the swept-sine and the periodic noise are better signals for measuring the frequency response of
systems that exhibit a slight nonlinearity.

General

"Some general recommendations:
• The MLS based system is inferior to swept-sine or periodic noise driven systems when
implemented with a regular PC soundcard.
• The swept-sine based system gives the best estimation in a low-noise environment.
• The measurement system with a periodic pink noise excitation gives the most robust
estimation, and can be thought as a general purposes system."

[AJINFLA]

M-Audio mobilepre and ECM8000. That's TruRTA, yes in 1/6th octave smoothing mode.

cheers,

AJ

[brianpowers27]

M-Audio mobilepre and ECM8000. That's TruRTA, yes in 1/6th octave smoothing mode.

cheers,

AJ

MLS/Sine/PN?

I am happy with the m-audio products. I am also using a behringer ecm8000 (calibrated, of course.) I found that the low frequencies roll off early, when uncalibrated.

[Undefinition]

back to the topic at hand :

I figured out the solution to the RS dipole design dilemma. This came to me while sitting there, gazing into the beauty of the Sunflowers... :roll: (I'm allowed a bit of hyperbole)

What I can do is simply make new top sections for the Sunflowers (the U-frame) to design with the other RS drivers. That way, I don't have to make a new bass bin, just new MTMs (I think I still have that curvy template around the garage somewhere). Then, I'll do a version with the RS150-4 mids + BG Neo3 tweeter, and hopefully a TMW with the RS180 as a mid + ? ... I dunno what tweeter. (Maybe I'll bring the RS28a back out for that). The weather will be getting warmer, eventually. And those are sort of "side projects," not full blown soup-to-nuts ordeals. So I'm excited with that solution. :B

So no "all new dipole project"... for now, anyway.

[brianpowers27]

with the RS180 as a mid + ? ... I dunno what tweeter. (Maybe I'll bring the RS28a back out for that).

I would love to see you cross to a seas t27 at 1500hz.

P.S. Could you throw on a 5/8" super tweeter(Think Dispersion)?

[AJINFLA]

MLS/Sine/PN?

PN.
Now hopefully Paul can measure the extension of his ported bass section, for the proposed design, in room.
I see no reason why the RS150 couldn't or shouldn't be used for this type design.

cheers,

AJ

[BOBinGA]

Paul, I'm interested and I'm already one step ahead of you. I started my project over a year ago and it includes a single RS225S-8, a single RS150S-8 and a horn loaded Seas 27TBFC_GTV. This is where I'm at:



That's my old DQ10's next to it.

So far it's sounding pretty good. Here's the in room FR from about 10 feet:



Notice that the divisions are 2 db, so it's getting very close to flat. I'll start a thread on them soon, but first I want to finalize the crossover and get a coat of paint on them.

-Bob

[ttan98]

Bob,

How does it compare with the Quad you have next to it?

[BOBinGA]

They look like Quads, but they are Dahlquist DQ10's. The sound is similar frequency-wise, but they are different. The DQ10's have what I would call a richer harmonic flavor. But when I switch to the new ones, it becomes obvious that the richness is harmonic distortion. The DQ10's have well deserved reputation for a spacious sound (being one of the original cone speaker dipoles), but I have to say, the new ones project an even bigger image. I built the new ones to see if I could improve on my old trusty DQ10's and I think I succeeded.

[Jed]

Bob,

Have you measured the frequency response of the Dahlquist? I'd bet the warmer tonal balance is frequency response related. Just curious.

[BOBinGA]

The DQ10's FR is slightly more ragged, but still reasonably flat. I'll see if I can dig up an old measurement. But I haven't done a measurement in the same room with the new ones yet. I might have to do that before I start a thread.