D'apolito design-good or bad?

[evac311]

I own a pair of Infinity RS-5 tower speakers. Before I purchased them, I looked into the RS-4's which had the same type of drivers, only instead of a tweeter sandwiched between two midrange drivers, it had one tweeter mounted above one midrange. Now conventional wisdom leads me to believe that paying $200.00 more per pair just to have an extra midrange driver identical to the other is somewhat of a waste. I want to know if infinity changed the crossover frequency and what the advantage of this design is.

[chimera128]

http://www.audiovideo101.com/dictionary/dappolito.asp

[kexodusc]

The D'Appolito design, more commonly referred to as MTM configuration in the DIY world (mid-tweeter-mid) has withstood the test of time and has been the model for some of the world's finest sounding speakers. Without writing a book, the pros heavily outweight the cons. Especially if you use a good tweeter with excellent off axis response.

The fact that you paid $200 more for the midwoofer and extra cabinet material is more of a reflection of the huge markups on commercial speakers...

The frequecy where the crossover feeds the tweeter is likely the same if the tweeter is identical and the woofers are the same, however, the crossover itself would be considerably different.

Your speaker probably plays louder, and cleaner, with a slightly fuller midrange than the RS-4. More bass too, I'd suspect. If Infinity did it right, it should be a much better speaker than the RS-4.
Enjoy.

[abstracta]

I've heard many D'Appolito configurations. The most infamous I'm familiar with is likely the Legacy Focus, which has perhaps the most controversial review archive on record.

The main advantage of a D'Appolito array in a tower speaker is it creates a vertical 'null zone' which is very resistent to ceiling/floor boundry reflections and is able to project a very accurate portrayal of the speakers near field reponse to a far field listener. In most respects, it's a good thing. I believe Koss speakers for years had a very popular, low cost D'Appolito design they sold in low end department stores as fast as they could make them. Thanks to the 'null zone' nature of the D'Appolito alignment, the speakers sounded really good in basement showrooms or displayed next to house-wares.

The bad is that D'Appolitos can sound very, very forward and clinical. As components of the sound spectrum get diffracted and absorbed by the room, the frequency range of your mids in the D'Appolito config stay linear, so that's what you hear the most. D'Appolito's also tend to be 'head in a vise' type designs with very limited vertical lattitude forcing you to sit at a very defined height as you listen to music. Horizontal listening lattitude is normal.Doesn't matter where you sit on the couch so to speak, as long as you don't slouch :-)

For these reasons I've found D'Appolito's tend to prefer set-ups where the room is a bit wider than longer, alothough this is not a rule. I won't waste time arguing though that I've found every D'Appolito config to be "forward" sounding in the mid range (not necessarily bright), and brutal on mediocre recordings because the midrage is coming right at you and un altered by room reflections. If this is your listening preference, you'll love them. If you prefer more laid back speaker response where the drivers and crossovers place emphasis on being neutral and masking their own colorations even if it means losing detail, you might not like a D'Appolito.

[evac311]

"For these reasons I've found D'Appolito's tend to prefer set-ups where the room is a bit wider than longer"

Interesting that you say this. I have always found this to be the case with these speakers, and wondered why until now. I'm moving in a couple weeks, so this is good information to have when I consider speaker placement.

Thanks for the insight.

[kexodusc]

I wonder if the brightness and "forward" or "clinical" sounds spoken of are a direct result of the design, or an indirect result.
One thing I've noticed about MTM/D'Appolito designs is that they tend to get the most out of otherswise cheap, unlistenable drivers. I've seen a lot of mediocre tweeters and midrange units aligned in this manner, possibly contributing to results you speak of.

The Seas Froy MKIII model is one of the softest sounding speakers with a wide, and deep 3-d soundstage and certainly doesn't sound forward or bright.

From what I understand, there's been a shift in designs over the decades towards the so-called "forward" sound, for whatever reasons. Creating a more balanced sound, even in a D'Appolito config, shouldn't be difficult, however. I would argue that brightness and "forward" midrange is a failing (or intentional character) of the crossover design (probably low resistor values) rather than aspect of the D'Appolito config itself.

I would disagree with the assessment that mid-range frequencies become linear in a D'Appolito config (at least any more so than any other typical speaker design-we'll leave 'stats and planars out of this for now)...wavelengths of mid-range frequencies are fixed regardless of speaker design or driver alignment, and in the most common 6.5" mid-woofers, you have little to worry about with mids becoming linear as wavelengths approach the size of this relatively large driver. You may be hearing this phenomenon in a room, but it is certainly not unique or attributable to the D'Appolito configuration.

[abstracta]

No disagreement. Especially the part about cheap drivers sounding better in D'Appolito configs than standard alignments, which again likely has something to do with D'Appolito's isolating the dispersion of the driver, and choppy dispersion patterns are a typical problem with poor drivers. I also agree that the forward nature of D'Appolito configs can be deal with by better crossover design, or less aggresive drivers. It's just that there's been a trend in audio for a long time for speakers to deliver strong forward midrange performances - mostly to show off somebody's $400 CD/DVD player and $2000 speakers :-)

I other respects, D'Appolito's sound like big near field monitors to me, which I believe is a focus of their design - create a monitor like performance at a distance. In an odd way this creates the inverse problem because if your lower mids and crossover slope are getting diffused and abuse by typical room interactions, and your central midrange response isn't because of a D'Appolito sewwt spot, it might result in the 'forward sounding' nature.

Interestingly enough I've heard some quad D'Appolito configs where the drivers are in a two by two array (usually very expensive), and the problems go away. They sound like planars at that point.

[kexodusc]

I can appreciate nearfield listening....In most rooms, if you sit at the typical equilateral triangle point between your speakers so far back, 60% or more of the sound you hear is reflected (unless you've done treatments)...nearfield gets around this quite a bit.

But for those of us in the real world who have room limitations (or women living with us), that's just too impractical for so many reasons.

I've always liked a good 2-way...but lately I've been seduced by a D'Appolito designed transmission line speaker in an MTM aligment...If I didn't just have to replace my hot water tank and water pump, I might splurge...

[3db]

I hear ya loud and clear. Its bizaare how the spousal unit can have such a profound affect on room acoustics

I can appreciate nearfield listening....In most rooms, if you sit at the typical equilateral triangle point between your speakers so far back, 60% or more of the sound you hear is reflected (unless you've done treatments)...nearfield gets around this quite a bit.

But for those of us in the real world who have room limitations (or women living with us), that's just too impractical for so many reasons.

I've always liked a good 2-way...but lately I've been seduced by a D'Appolito designed transmission line speaker in an MTM aligment...If I didn't just have to replace my hot water tank and water pump, I might splurge...

[kexodusc]

3db: When I was replacing my Studio 20's...even after all these years, she wanted to know why we didn't buy those cute little cube speakers...silver at that!!!
I fixed that pretty quick when we were grocery shopping and I asked why she needed to buy $35 shampoo every month while I washed my hair with the same stuff we use to wash the dishes.

[evac311]

I can appreciate nearfield listening....In most rooms, if you sit at the typical equilateral triangle point between your speakers so far back, 60% or more of the sound you hear is reflected (unless you've done treatments)...nearfield gets around this quite a bit.

But for those of us in the real world who have room limitations (or women living with us), that's just too impractical for so many reasons.

I've always liked a good 2-way...but lately I've been seduced by a D'Appolito designed transmission line speaker in an MTM aligment...If I didn't just have to replace my hot water tank and water pump, I might splurge...

How do I create a "nearfield" setup? Would it be to simply move my couch closer to the speakers in the equilateral triangle

What is the best setup with D'Apolito speakers, less distance between listener and speaker, or more distance?

The reason I ask this is that I generally find that the farther I sit from my speakers, the better they sound. It seems like if you sit farther from the speakers, they would sound better because you can run them at a higher realative volume.

[Jon Lane]

Hang on folks. The vertical D'Appolito is not a common MTM and vice versa. The former is usually associated with a 1st order transfer between drivers and an alignment of driver acoustic centers which grants a +/-1.5dB response in the vertical plane.

(Yes, this is the theoretical off-axis tolerance and actual systems have variances due to driver dispersion. IOW a real-world, 1st order D'Appolito doesn't have flat off-axis power response unless the drivers somehow do also.)

An MTM, on the other hand, can obviously use any crossover and each will result in different polar and power responses, with at least the even order systems giving the nulls above and below the centerline. As I recall, the 3rd order version is also +/-1.5dB flat vertically, but doesn't have the minimum phase characteristic of the true "D'Appolito" 1st order system.

All this from memory so correct me if I'm wrong...

The odd-order MTM's are great for center channels due to the symmetry of what is now the horizontal polar radiation, but the non-technically perfect even-orders and the thow-it-in-a-box MTM's have less to recommend them as horizontal centers or as vertical mains, IMHO.

With all these variants and only one real D'Appolito design, it's easy to see why results vary so much.

[kexodusc]

How do I create a "nearfield" setup? Would it be to simply move my couch closer to the speakers in the equilateral triangle

What is the best setup with D'Apolito speakers, less distance between listener and speaker, or more distance?

The reason I ask this is that I generally find that the farther I sit from my speakers, the better they sound. It seems like if you sit farther from the speakers, they would sound better because you can run them at a higher realative volume.

Evac311: If they sound better farther back, no need to change...but if you just want to experiment, then yes, you move closer in between the speakers.
The short, simple explanation is that you are reducing the reflected sounds off the rooms walls, etc and getting the pure response from the speaker...this should be better than sitting "farfield", but it's not always so. It really comes down to the indivdual speakers in question, and the sound preferences of listener.
In other words, there's no universal "best".

Jon Lane: You're quite right, there's more to the D'Appolito design than just MTM...though I'm not sure it's fair to say there's only one D'Appolito design anymore. Joe D'Appolito has revised the design a few times himself, as have countless others, so I'm not sure the"original" D'Appolito design holds-up anymore...seems only natural...take what works an improve on it if you can.

[Sir Terrence the Terrible]

Evac311: If they sound better farther back, no need to change...but if you just want to experiment, then yes, you move closer in between the speakers.
The short, simple explanation is that you are reducing the reflected sounds off the rooms walls, etc and getting the pure response from the speaker...this should be better than sitting "farfield", but it's not always so. It really comes down to the indivdual speakers in question, and the sound preferences of listener.
In other words, there's no universal "best".

Actually Kex, the reflections are not reduced, they are still there. However sitting closer to the speaker allow the speakers direct output to reach us first. Its called the "presendence effect". The speakers direct output is stronger than the amplitude of the first reflection. Great way to listen if you want to somewhat remove the room from the equation.

The reason I ask this is that I generally find that the farther I sit from my speakers, the better they sound. It seems like if you sit farther from the speakers, they would sound better because you can run them at a higher realative volume

That is because you are listening to the direct output of the speaker, and the rooms reverberation and sonic signature combined. There is a certain point in front of the speaker were both of these are actually the same amplitude. Highs tend to roll off the further you are away from the speakers.

[incidentflux]

D'Appolito's also tend to be 'head in a vise' type designs with very limited vertical lattitude forcing you to sit at a very defined height as you listen to music. Horizontal listening lattitude is normal.Doesn't matter where you sit on the couch so to speak, as long as you don't slouch :-)

For these reasons I've found D'Appolito's tend to prefer set-ups where the room is a bit wider than longer, alothough this is not a rule.

This explains D'Appolitos, but I felt similar lack of height, with the GoldenEar Triton Three, which is technically strictly not a midwoofer-tweeter-midwoofer design like big brothers, the Triton One and Twos.

Tricky business...

[Owen Ekman]

I am looking to buy a pair of Tannoy Jupiter S speakers which I am not certain of: D'Apolito design or one passive woofer. Does anybody know about these? They could be J30's, as the Tannoy archives list the Jupiter as a two way, two speaker design.