[AudioSoul]

OK, Im one of you guys now. I purchased a pair of Common Sense Audio Super 8  drivers. I know not to exotic, but , hey a guy has got to start somewhere. I plan on driving them with a Assembleg
ST-40 amp (40watts) Is that too much? Again I am just starting on the journey so things will change over time. Any comments, suggestions. critiscizems? Thanks

[richidoo]

Welcome to the wacky world of single driver speakers!

The drivers are rated 30W, so you'll be fine with the 40W amp. The secret is never turn up a speaker to the point that it sounds bad. That's your warning that damage is possible. A more powerful amp is actually safer than too small, which will distort more easily. The distorted signal can do damage easier than a powerful but clean signal from the amp. But every speaker has a power limit, even from a clean amp. But in your case (96dB sensitivity) that would be so loud you'd be driven from the room long before any damage could occur.  Your amp should be able to make 111dB before it starts to distort noticeably at around 30W. That is a painful and dangerous volume level, so your ears will protect your speakers.

In what kind of cabinet/baffle will you mount the drivers? It is fun to try all the different enclosure types.

[AudioSoul]

   It is going in a vented enclosure 34h x10w x 12d. Do those dimentions sound about right?

[richidoo]

That  might be fine, but more important than the size or shape for a bass reflex box is the relationship between the driver specs, box internal volume and the port geometry.  A cool free little program I use for simple box design is WinISD.
http://www.linearteam.dk/

Plug in your driver specs, then adjust the box dimensions and port geometry to make the frequency response look like you want. Use some soft stuffing inside to taste. Google "loudspeaker Qtc" to help you know what you want.
http://www.members.shaw.ca/loudspeakerbuilder.ca/thiele-small.html

Brace the box internally so that the walls don't vibrate. Factor in the volume of the bracing so you still have the required volume.

[JLM]

Good attitude (regarding crossovers).  The essence of the music is the midrange and should not be messed up with extraneous component that introduce phasing errors/etc.  The coherence of a single driver design cannot be matched and is essential IMO for nearfield listening (the best/proper setups, again IMO).  To our discredit, fans of single driver loudspeakers too often neglect the huge advantages of active design (one channel of amplification per driver): flatter frequency response, huge dynamics, and unbelievably deep bass (from what "the straights" would expect from a single driver).

Speaker diaphragm/cone is too thin to be anything but acoustically transparent (or at least opaque).  So some of the sound inside the cabinet (with overall energy levels equal to that outside the cabinet, but much more concentrated - translate higher sound pressure levels) escapes via the diaphragm/cone.  If you visit the acoustics circle and study how room shape, absorption, and diffusion can help (or hurt) with anomalies you can understand how the same principles should be applied to the inside of the cabinet too.

Try to skew (slope) the back cabinet wall or add a diffuser (check Fostex, they sell such a little beasty).  This is why even some sealed speaker cabinets have tapered sides/etc.  This idea is nearly uniformly used in horn loading, tuned quarter wave pipe, and transmission line designs.  The horn designers fixate over the size, shape, and padding within the compression chamber (the space directly behind the driver).

[AudioSoul]

   David at Audio Nirvana helped me out with the port size for the size box I wanted to go with.
   I am making the boxes out of 3/4" birch plywood. I have the pieces cut out, I just need to
   assemble them and spray a finish on them and install the drivers. I will report back on how it
   goes, if anyone is interested............ aa

[roscoeiii]

Hi AudioSoul

What driver and box/port size did you end up going with? I've got Audio Nirvana 12" stamped frame drivers in David Dicks 2.8 cabinet with 2 3" ports, though I hear he is recommending a single 6" port these days for better bass. Not as much a concern for me since I suplement the lower end with dual subs. I'm thinking hard about grabbing some 12" cast frames while they are on sale, maybe open baffle this time (again, because the bass can be addressed with my subs)

Enjoy your project.

-Roscoe

[Wind Chaser]

Good attitude (regarding crossovers)...

BAD ATTITUDE!!  Been there done that, but have moved on, forward beyond the limitations of no crossovers and wide band drivers.  The fact is not all crossovers are equal.  The best world class sounding speakers all have one thing in common - crossovers.  In fact if you think about it, there really isn?t a world class speaker that takes the no crossover approach.

A good wide band driver with the right amp can sound very good within its limitations.  However the limitations are real and the compromises are undeniable.  My journey with crossoverless wide band drivers began with Fostex and the HornShoppe.  Nice mids but very limited LF output and screaming highs.  I heard a few other Fostex drivers, which were essentially more of the same.  I tried the Jordan JX-92s in a few different configurations, definitely better than the Fostex drivers I heard, but not as efficient and still not as refined as the better 2 way systems.  The B-200 was a hoot, but in reality just a different flavor combined with the usual problems associated with crossoverless wide band drivers.

Bottom line? No crossover = limited LF output, unbalanced FR, shouting top end that prematurely rolls off.

[JoshK]

One question for those in favor of no crossover.  How do you overcome baffle step?  Baffle step is real and undeniable.  Its physics.

Food for thought.  For those that believe a major advantage of single drivers is phase coherence, what happens to phase above the break up frequency?   All single drivers rely on breakup to produce their highest frequencies.

[JohnR]

One question for those in favor of no crossover.  How do you overcome baffle step?  Baffle step is real and undeniable.  Its physics.

Lots of well-known solutions... LR network (no, that is not a crossover... ), placement near wall/corner, back-loaded horns, bipole... probably others I don't know about.

Regarding phase, perhaps that's one of the things that differentiates better drivers in some way.

[TerryO]

Good attitude (regarding crossovers)...

BAD ATTITUDE!!  Been there done that, but have moved on, forward beyond the limitations of no crossovers and wide band drivers.  The fact is not all crossovers are equal.  The best world class sounding speakers all have one thing in common - crossovers.  In fact if you think about it, there really isn?t a world class speaker that takes the no crossover approach.

A good wide band driver with the right amp can sound very good within its limitations.  However the limitations are real and the compromises are undeniable.  My journey with crossoverless wide band drivers began with Fostex and the HornShoppe.  Nice mids but very limited LF output and screaming highs.  I heard a few other Fostex drivers, which were essentially more of the same.  I tried the Jordan JX-92s in a few different configurations, definitely better than the Fostex drivers I heard, but not as efficient and still not as refined as the better 2 way systems.  The B-200 was a hoot, but in reality just a different flavor combined with the usual problems associated with crossoverless wide band drivers.

Bottom line? No crossover = limited LF output, unbalanced FR, shouting top end that prematurely rolls off.

I'll have to disagree with you as far as the degree of limitations that you mention. Every speaker is compromised in some manner or other. Almost all 2-ways require the crossover frequency to be smack-dab in the middle to upper frequencies of the vocal range. A three-way with a wide range mid has a far better chance of being a good sounding speaker that a typical two-way although we all know that there are exceptional examples that seem to violate this "Ironclad" rule.

As for "world-class" speakers, it would be nice if you would define what exactly that means, and in what listening enviornment they are used. I might add that a lot of "single drivers" use whizzer cones to extend the high frequencies. As you may (or may not) know, these are actually two-way drivers as the whizzer is controlled by what is actually a  mechanical crossover.

Your final "bottom line" statement is not only such a broad generalization that it has little merit, but examples can be shown that don't have these issues to any great extent. Depending on what examples you have in mind, I'm sure that most, if not all, multiway speakers  have compromises in these areas as well.

In the end, balancing the compromises is what leads to a good speaker, not some abitrary designation.

Best Regards,
TerryO

[JoshK]

One question for those in favor of no crossover.  How do you overcome baffle step?  Baffle step is real and undeniable.  Its physics.

Lots of well-known solutions... LR network (no, that is not a crossover... ), placement near wall/corner, back-loaded horns, bipole... probably others I don't know about.

Regarding phase, perhaps that's one of the things that differentiates better drivers in some way.

Iagree, an LR isn't a crossover, but I got the impression that passive components between the amp and the driver were verbotten from reading this thread. I'd probably try a passive line level network. I'd have to see measurements to believe that a BLH is broadband enough with 6db/octave to overcome the BS.  Might be possible, but it isn't intuitive, to me at least.

[JohnR]

Oh, right, line-level EQ is another way

There are some articles on Martin King's site with simulations of BLH responses - afraid the math is completely beyond me but the graphs are interesting : http://www.quarter-wave.com/Horns/Horn_Theory.html

[JLM]

All drivers work within a frequency range, some have a bigger workable range than others.  It seems that too many multi-driver "traditionalists" seem to forget this fact.  They see "single driver" and instantly react.  Funny that the "straights" look at something like VMPS designs (that use an extended range (5+ octaves) midrange driver and they don't go nuclear at all.  Bottom line: the perfect audio (fill in the blank with anything you'd like) doesn't exist.  We all pick our compromises.

I'm now using DEQ primarily to replace a baffle step/zobel circuit (and provide a more direct connection between monoblocks and drivers).  It has provided flat frequency response and extended frequency response (both huge advantages in this Cardas room/setup with absorption panels).  Improvements are huge (as I've stated elsewhere).  We all use various mechanical devices (baffles, cabinets, room boundaries, whizzers, wave guides, horns, phase plugs, etc.) as some sort of "helpers".  Some just take the more extreme measures of using frequency specific drivers with crossovers.

I'll agree with Wind Chaser that you have to work within the limits of the driver (applies to any speaker, regardless of the number of drivers) and that most Fostex drivers are thin and shouty, but not my F200A's.  Even the B200 is best described as a 9 inch midrange/tweeter.  And I've never been particularly impressed with the Jordans either.  I'll be the first to say that nearly all single driver purists I've met (where no subs are "allowed") have conditioned themselves to believing that deep bass isn't needed (or even deny or find it distasteful that it exists in music).

Wind Chaser, I congratulate you for trying single driver designs and am sorry it didn't work out for you, but coming here to bash the concept doesn't seem appropriate.

[Wind Chaser]

Wind Chaser, I congratulate you for trying single driver designs and am sorry it didn't work out for you, but coming here to bash the concept doesn't seem appropriate.

I didn't come here to bash the concept, but to address the title of this thread as I also once held that POV.  The sins of a crossover are not worse than that of a wide band driver.

I agree with you that in any approach there will be compromises, but in my experience, the compromises of crossoverless single drivers are much greater.  Most of the music happens in the midrange and that is the strength of the single driver.  However just as seasoning brings a bland dish to life, so does addressing the frequency extremes make the midrange more palpable.  Crossoverless full range drivers tend to be very conservative with bass and very liberal with treble.  That, like bad politics, creates chaos with the masses, or in this case the midrange.

While I was yet in my love affair with wide band drivers, I use to scoff at elaborate crossovers working in the ?critical midrange? as they say.  That was until I heard some speakers that were so much obviously better than my own, and not just in the in the frequency extremes either.

Like it or not, the fact is a crossover operating even in the midrange can sound more coherent and complete in the mids than any full range driver.

[Mariusz]

OK, Im one of you guys now. I purchased a pair of Common Sense Audio Super 8  drivers. I know not to exotic, but , hey a guy has got to start somewhere. I plan on driving them with a Assembleg
ST-40 amp (40watts) Is that too much? Again I am just starting on the journey so things will change over time. Any comments, suggestions. critiscizems? Thanks

I've used AN 15", 8" & 6.5". They're all very easy to drive. 15" might need an extra muscle to properly control its enormous size cone. In your case - 40wpc (for 12 incher) should be fine.

[doug s.]

then hell must rock!!!     i love my decware-modded fe206e drivers in oris 150 horns.  (i loved them w/the stock fe206e's as well.)  but, i don't think i'd be in love if i wasn't crossing them over to woofers, and the woofers to subwoofers, w/my deqx.     w/any speaker - single-driver, wide-range driver, or standard-crossover'd speakers, the key is the total package.  i have heard excellent iterations of all types..

ymmv,

doug s.