Input welcome on high SD 2-way "book-shelf" speaker

[dirkwright]

The ER18DXT is not a conventional bookshelf and if you try to change it you risk ending up with something that sounds worse. This a narrowing constant directivity design, similar in concept to the Geddes speakers. Make note on how the narrowing directivity of the woofer at the crossover point is perfectly mated to the waveguide dispersion pattern of the tweeter. Horizontal constant directivity is often overlooked in conventional designs but it's known to be instrumental in achieving a convincing stereo image and correct perceived tonal balance.

P.S. I've never built it or listened to it but it looks great on paper.

Yeah, that is a very carefully thought out design. If I were to build it, I'd copy it exactly.

 

[Havoc08]

Just wanted to say that we're building them to fit the role as primary speakers. Even if they are a bit on the large side, the will do a great job as "book-shelf" speakers, especially due to the fact that they use an aperiodic vent.

Hi Sachagabor. Didn't mean to demean them in any way. I just followed the links in the thread and got that perception from some of the posters (it's almost a direct quote what I said). I'll read through the rest of your thread.

Hi !
Some of them, yes ! I don't listen to compression a lot but i heard one which works very well, i don't have its reference.
It could an interesting to use a compression, but a good compromise could be a tweeter + waveguide.
This troëls project could be a good staring point ? 8" +1"WG

That is actually my inspiration as I find the DTQWT awesome! . The 2 way is however slightly on the large side for my liking. You might as well go floor standing at that point.

Oh, good horns are the cat's meow! There is an entire sub-culture of horn enthusiasts in high end hifi.

The B&C DE250 is generally highly regarded. Also, I have read that compression drivers that do not use titanium or aluminum diaphragms generally sound better. There are other good sounding compression drivers out there.

I'll read a bit about these drivers, I hope they perform well as I also love the sound of unipoint speakers, i.e. fullrange, but have yet to see a 6-8" design with a nice and flat FR (flame wars... 3..2..1 ).

The ER18DXT is not a conventional bookshelf and if you try to change it you risk ending up with something that sounds worse. This a narrowing constant directivity design, similar in concept to the Geddes speakers. Make note on how the narrowing directivity of the woofer at the crossover point is perfectly mated to the waveguide dispersion pattern of the tweeter. Horizontal constant directivity is often overlooked in conventional designs but it's known to be instrumental in achieving a convincing stereo image and correct perceived tonal balance.

P.S. I've never built it or listened to it but it looks great on paper.

Thanks alot Boris. I read the wiki on narrowing directivity and a couple of pages into this http://www.pispeakers.com/Pi_Speakers_Info.pdf and http://homepage.mac.com/rodken/PDF/B2001/KennedyBC2001c.pdf
I see that you don't just fiddle with it. I was also trying to understand why the creators of the ER18DXT choose that tweeter instead of my proposal, but maybe it will occur to me while reading some more on the design. Appreciate your input.

 

[audiokinesis]

IDK about horns, I mentally tie them to dance club and PA and not to HiFi, but I might have the wrong perception? ....Are compression drivers "good enough" for normal living room HiFi?

Good horns & compression drivers are imho quite competitive, but the crossover design is considerably more challenging than with direct-radiator drivers. I see from your post just above that you've found the Pi Speakers site; that's a great resource and Wayne Parham's designs are excellent... though like most horn speakers, not really "bookshelf".

 

[Michael Chua]

IDK about horns, I mentally tie them to dance club and PA and not to HiFi, but I might have the wrong perception?

There are a wide variety of compression drivers and horns, from budget to quality ones. The JBL2342 were used in the JBL4425 Monitors in the 80s. Mated with the JBL2425, the combo is pretty good. It would be better with a JBL2440 but cost would be prohibitive. As it is, they are a bit costly for HiFi already.

 

[jerome69]

...I was also trying to understand why the creators of the ER18DXT choose that tweeter instead of my proposal, but maybe it will occur to me while reading some more on the design...

Not sure you discover something... There are a lot of reasons to mate two drivers Your proposal is not worse than using a the DXT but you must change the crossover.
Directivity is only a parameter among others. Not the main parameter and use this as an assertion closes a lot of other possibilities
I understand you want to use a large Sd ? a 7" is not a large Sd 130cm², soundstage is small. Using 2x7" is a better choice.

Talking "High Sd" means for me high sensitivity, huge soundstage, high power handling, big box, low distortion...
The "Michael Chua"'s proposals are very interesting
This is an other loudspeaker which can shock but exist 15" + 2" compression 100dB sensitivity : 15MI100 + DE250&RCFH100
http://www.hostingpics.net/viewer.php?id=983279DSC00160r.jpg

There are high end speaker with big drivers. HiFi world could be very closed, open our mind Yes some PA drivers could be high end !

 

[River757]

but a good compromise could be a tweeter + waveguide.

I hope I'm not "polluting" this discussion by mentioning another already-built commercial loudspeaker, but the idea of a dome tweeter combined with a waveguide always seemed like an interesting idea that I thought might be a cure for the typical (inexpensive) horn+compression driver's rather forward & sometimes overly analytical quality. So when Cerwin-Vega introduced their CLS series about four years ago, I immediately noticed their use of a soft-dome tweeter* + wave guide. Here's the newest series, in this case a 3-way model with 12" woofer. BTW two audiophile publications, Soundstage.com and TAS reviewed the dual(!!) fifteen inch woofer model and both gave it an overall positive review.

I'll just read this discussion from now on.

* supplied by Vifa; uses a copper shorting ring to reduce distortion

 

[wolf_teeth]

M8n + DX25..

MAX pictures by wolf_teeth_speaker - Photobucket

It's a vented design, but sensitivity is rather high, and it's only 34 ltrs.

Not a build for the amateur, that's for sure.

Later,
Wolf

 

[Michael Chua]

JBL L3

I wonder how they do it.
8" 2-way crossed at 3,000Hz.

 

[boris81]

Not sure you discover something... There are a lot of reasons to mate two drivers Your proposal is not worse than using a the DXT but you must change the crossover.
Directivity is only a parameter among others. Not the main parameter and use this as an assertion closes a lot of other possibilities
I understand you want to use a large Sd ? a 7" is not a large Sd 130cm², soundstage is small. Using 2x7" is a better choice.

Jerome,
Directivity is a design parameter just as sensitivity and distortion. It should not be undermined but instead considered in relation with the rest of the parameters to find the most optimal fulfillment of the requirements. In simple terms you are proposing that playing louder is more important than how the system interacts with the room.

I am interested in exploring this matter further but I believe it goes beyond the scope of this discussion. I have created a new thread and I invite you to bring your ideas over there.

Large vs. Small midrange

 

[jerome69]

Boris I am agree with you
It is a good idea to create a new thread

...
In simple terms you are proposing that playing louder is more important than how the system interacts with the room.
...

Yes because i play loud.
But it is also something where a lot of researches should be done : the shape of the baffle (directivity ?) and its sound in the room.
Note very directive speaker should less interact with the room ?

 

[speakerdoctor]

Here's a complete mod to a vintage KLH-17 cabinet to consider. HiVi F8 and fountek ribbon. This was done in a mirrored pair. Design and plans available.

 

[Havoc08]

Hi again all.
Thank you for your replies.

I am following the other midrange thread also and have decided that for now, I'll make the ER18DXT, as I do not have my workshop here in the states and it does sort of what I want (although I just saw that it is not very sensitive either) in a PE baffle which is great as I have very little tools atm.

Thank you all for your input .