[miklorsmith]

The Zu is a simple high pass

. . . and not seen by the main drivers.  Not to belabor the point but I believe this is a significant part of their success.  I'm honestly surprised more manufacturers aren't trying similar strategies.

I totally agree about the Omega hemps too, mmm mmm delicious.

[Ed Schilling]

MSmith,
We are not laboring here or even arguing.
The HP section of any xover is never seen by the woofer. One of the reasons to eliminate it (ANY xover)is the phase shift it causes between the driver it is hooked to and the one it is not. Sort of.

The Zu is a classic 6dB xover with no LP section. It has a resistor to match levels. It introduces a phase shift. If set at 12K it will only be 6dB down at 6K and this is not insignificant. This is not unconventional and these points can not be argued against. They are fact. Xover design 1 oh 1.

I bet if you listen to them without it hooked up they will not play that way long. The ST is critical to the design. I do not view it as being used to "supplement" the mains. At 6dB set for 12K it is contributing a LOT.

Imagine if you used 36dB per octave set At 12K.......as a mental exercise....I would guess there would be a "hole" in the sound around maybe 4-10K. I guess this because at 36db there would be little if any output at 6K.....since they do what they do I trust it is for a very good reason and their approach seems quite valid and obviously is. But I see it for what it is.......a 2 way with the HP set for 12K instead of 3-4K. It has all the "problems" of ANY other 2 way with no LP section. Because that is what it is.....

I am NOT knocking it!

I agree with you............more should use this approach, I have many times. Lots of wide band drivers work better with tweeters.

Dave,
I would suggest that max volume one can tolerate in a SD speaker is limited by excursion......NOT what the driver is capable of, mind you, but rather how much it is moving while playing, before the sound becomes slurred. For instance, if you gave the driver I use 5 times the excursion using a magic wand....they would not go a bit louder. They are limited by excursion in that regardless of what the driver can make the limit will be how much it is moving before it sounds bad. I hope I am making this understandable.

I think what makes the Feastrex good is not much related to excursion capabilities...assuming there is enough for a desired output.

It has generally been accepted in the past that lowering excursion lowers distortion...I did not say it I think guys like PWK said it. It is why big woofers exist...to move more air with less excursion and therefore lower distortion. If you could make a 3 inch speaker have 3 feet of excursion it could make lots of "bass" but the distortion would be off the chart.

But I am musing about DRIVERS not systems! There may be exceptions in systems. Maybe.

Raising excursion capability does not lower distortion (at least that is MY take on it), but that does not mean a low distortion driver might not have high excursion. It is just using that extreme excursion past a certain point may cause distortion problems, regardless of whether the driver is at the limit of what it has.

Hey, I'm just tossing it out here.......so far so good.....no one upset yet. And please take my posts as "food for thought" not "Ed's definitions"! Except the xover stuff.....look at this....adding the cap does not affect the woofer and eliminating the coil does not affect the tweeter.
http://www.trueaudio.com/st_xov_1.htm
Ed

[jrebman]

Ed,

This won't surprise you, as it didn't surprise me, but I talked to the owner of the Feastrex drivers that Dave mentioned, and he is disappointed in it's ability to play loud.  He told me that it gets too distorted and breaks up at loud levels.  I told him he was experiencing IM distortion and the only way he was going to get rid of that was to unload the speakers from having to reproduce the lowest octaves -- one way or another.

Although I suspect a different enclosure will help some too.



The way speakers used to be designed?  Well, for large spaces it was almost exclusively compression drivers and giant front-loaded horns.  That's how all the early movie theaters were filled with a pair of 12 watt amps.

-- Jim

[floobydust]

Hi Jim,

 Owning a pair of D5nf drivers, they will play very loud with 2-watts, and louder than I prefer with a larger 40-watt push-pull amp. I've used the Sheffield Drum record and they are simply amazing. I'm not sure what the other guy is referring to as an inability to play loud... exactly what SPL levels is he looking at? I would suspect problems elsewhere in the playback chain, but needless to say, there is always a limit based on size.

 Regards, KM

[jrebman]

Kevin,

Don't know as I haven't been over there to listen yet.  I just know he's disappointed with the ability to play loud rock.  This is with the SimpleSE SE 6550 amp, but other than that I really don't know any other particulars -- except that he's using the pine chang cabinets that Rich made.

-- Jim

[DaveC113]

I think the high excursion of the Feastrex and Omega drivers allow them to play lower frequencies than drivers with more limited excursion... but I agree it doesn't allow them to play louder. As far as excursion's effect on distortion, maybe there can be more excursion before audible "issues" arise than thought... maybe the driver's construction makes it possible? For purists who don't want to use a sub, thats great news... the XRS can play down to 40 Hz (in a small-medium room)... and for those who want a sub, integration at a lower x-over point makes the compromise easier to live with.

KM, we listened to the Sheffield drum recording too, we didn't have a meter but both guessed peaks in the mid 90 dB range, and that we wouldn't get much more out of them. I'd guess the Omega XRS are 6-8 dB louder, but the enclosure for the d5nf could be (a lot) better, the owner is working on new cabs... and his idea of loud is over 100 dB, which is pushing it for any single driver system.

--also... I heard the d5nf in the Maxxhorn cabs at last years RMAF, they got pretty loud, and had great bass response. This years version should be even better... for those with $20k to drop on a pair.

Dave

[Christopher Witmer]

Dave,

I'm pretty sure that the 5-inch drivers can't do 20mm peak-to-peak . . . hmm, 10mm "+"and 10mm "-" . . . well, maybe they can. I think the best time to test the excursion limits is when Mr. Teramoto is nearby to repair them if they reach the absolute limit of forward excursion, at which point they will probably cant and "hang" in the gap. He could put them back and they'd be no worse for wear but one wouldn't want to pay for their round-trip shipping to and from Japan just for that! I think keeping the range of excursion within half that amount would be prudent. It's eerie how the sound does not audibly distort even when such "dangerous" levels are being approached -- probably there is significant distortion but our sense of hearing is distorting too at such volumes so we don't notice it. (?)

I'm not 100% sure but I think drivers made using urushi lacquer on the voice coil former (an added expense) get some additional HF extension and also become more resistant to deformation under abusively large input signals. To my knowledge no D5nf drivers have been made with those urushi voice coil formers as Feastrex feels more powerful motors are needed to realize the HF benefits of the urushi . . .

-- Chris

P.S. This has a lot to do with the enclosure design as well but Mr. Teramoto insists that when everything comes together "just right," there is an apparent decrease in extreme excursion even as the amount of bass produced increases. I'm guessing this has to do with the way the driver couples with the air of the enclosure and room.

[Ed Schilling]

An example of what happens when you limit LF (excursion) in a single driver that can not move much air.....well, any small driver trying to punch below it's means....but with the small single driver the "modulation of the HF" makes the situation even worse in my opinion. With a phase plug as in the example below (or dust cap) where are the high freq. being generated? Are they being modulated by the LF?

http://www.audiocircle.com/index.php?topic=59356.0
Please read the last post by Dan. It looks like he likes it better when it's not flopping around.

The situation is the same for all single drivers .....excursion is not a good way to produce low distortion bass....and cone areas are small in comparison to say.....Zu....which we know "sound similar to a single driver". The largest, decent FR drivers seem to be 8 inches.

But wait....the Zu uses a large driver AND a HF unit..............and STILL sounds like a "single driver system". I wonder if by using this combo it is more efficient and  can go lower with less distortion than an 8 inch FR high mass cone?

I am just asking.

This is a good thread and I hope everyone is "cool" so far. We have mostly been in "agreeance" I think.

Ed

[miklorsmith]

The Def. 2s use 2 x 10" per side as the widebanders.  They also have 4 x 10" sub drivers per side.  They do the quiet girl with guitar thing very well but they throw down, NO compression all the way up to houseshaking volumes - very impressive.  They actually maintain composure and separation at any volume.

101 db at 6 flat ohms, my Yamamoto A-08s could drive them very nicely (and loudly) on 2 watts.

[Russell Dawkins]

The 12" driver in the Bastanis Prometheus http://www.baulsaudio.com/prometheus.html
is also run full range, and it seems to work as a design. I'm guessing the tweet is crossed in at 8 - 10k.
I seem to recall the sealed woofer being low passed at about 120Hz.

[Ed Schilling]

Yep. Tweeter helps those large drivers. We are a little off track but that is just fine. The tweeter in those designs certainly indicate neither wide band driver would make a good tweeter by itself, but maybe a decent mid range if used that way.

They are outside the 10 gram 6 inch territory anyway. Although I have no idea what the mms of their drivers might be I suspect it is not "heavy" for the cone area. I guess and I mean guess....less than a Fostex FW208N 8" Woofer at 40 grams. I just picked it at random since it is a "woofer" with a claimed fairly flat response out to 5k. My guess again is that the wide band Zu and Bastani drivers even with their larger cones are not heavier than the Fostex 8". Anybody know for sure?

If anybody thinks this thread is going somewhere profound I assure you it's not. That's not the purpose. It may give someone interested in building  a single driver speaker system some ideas however. For instance, it seems Zu and Bastani both want the single driver "magic" and no limitations. They both use tweeters and built in woofers to achieve this. Neither has a 10 gram 6 inch tweeter. And neither tries cover the low bass with the wideband. If crossed over at 120hz aren't the subs doing almost 2 octaves if one assumes a 40hz cut off instead of 20? And almost 3 octaves if one assumes 20Hz?

These are NOT criticisms...at all.....just asking the questions. And they are not trick questions either!

I didn't intend on this direction but hey, it's cool with me.

Ed

[DanTheMan]

This is a great thread and I for one appreciate it.  I've learned plenty and it is making the hobby more fun.  At this point I'd have to go back to the start to even remember what this thread was about--exactly.  It's interesting just to see what happens when someone poses an interesting idea or question.

Keep at it gentleman.

[DaveC113]

.....excursion is not a good way to produce low distortion bass....and cone areas are small in comparison to say.....Zu....which we know "sound similar to a single driver". The largest, decent FR drivers seem to be 8 inches.


Ed

This makes a lot of sense theoretically, but in my experience some of the best sounding low frequency drivers I've used have featured very high excursion designs, like the big Adire XBL^2 subs... I have a 10" in a sealed cab. It keeps up with the little 4.5" drivers really well, and is hardly noticeable x-overed at 50 Hz, which is no small feat. I think its possible that with good driver design and materials, that a high excursion design is also capable of low distortion.


So, if you CAN build a small driver that plays decently low without a lot of distortion.... it might end up being a good compromise. Why? Because you don't need a tweeter or a whizzer cone to augment the high end AND there are less issues integrating a sub, and less loss of bass w/out a sub. The small driver is faster and more accurate than the bigger cones, tone is more neutral, imaging is better....

I'm guessing the new Parts Express 3" SD speaker wasn't designed with bass in mind.

[Graham Maynard]

Mk I Druid crossover 'blurb' on this page -
http://6moons.com/audioreviews/zu/druid_3.html
I thought they changed the 'C only' for later models, not the inductor as well, but I could be wrong.

Re cone excursion muddying reproduction from smaller diameter drivers - the SD induced doppler distortion will increase beyond that already captured/inverted by the microphone and thus within the electrical waveform.

Adding a cap + supertweeter can be like adding a Zobel to a SD.  In theory it ought not have any effect to the SD itself (with the ST muffled and inaudible), but I have found that it can/does !!!   YMMV.
Then it can be very hard to acoustically integrate the SD and ST too, and always debatable whether it is better, or to have the ST upward pointing to increase 'air' without interfering with direct SD radiation.

90dB bass would not get through the door here.  100dB minimum, 110dB peak capability would do nicely, hence my augmentation with increasing OB cone area for increasingly LF.

Cheers ......... Graham.

[floobydust]

Kevin,

Don't know as I haven't been over there to listen yet.  I just know he's disappointed with the ability to play loud rock.  This is with the SimpleSE SE 6550 amp, but other than that I really don't know any other particulars -- except that he's using the pine chang cabinets that Rich made.

-- Jim

 Jim,

 I know the design.... but power output and power bandwidth can vary greatly based on the iron he used, the idle current and even the tubes to some extent. It's also a subjective call... as in they don't play loud enough, as in who's definition of loud. I've played some rock on these with a 40-watt push-pull amp. I was able to get it too loud long before running out of power, but that's my view whereas somebody else's would be different. If you make it over to listen it would be nice to get another viewpoint on how loud they go

 One last point.... not everyone remembers the D5nf is a 16-ohm driver and many existing tubes amps need to have the tap moved over or a different output transformer in case it doesn't have a 16-ohm tap.... just a thought.

 Regards, KM

[miklorsmith]

Ed - I'm running mine with a parametric EQ on the bass bins, currently crossing at 95 hz with a 24 db slope but I mess with it all the time.  It sounds fuller and fatter with a higher XO point and shallower slope but I'm bumping right up against male vocals with the settings I have now.  Going to a 36 db slope gets voices out of the subs entirely but a little meat is lost.  So, for Johnny Cash and similar I pull back the reins a bit.  Most of the time the limited bipole effect is terrific.

Distortion sensitivity in the bass is less, so is hearing of those frequencies in general - see Equal Loudness curves.

With the EQ my room measures flat or a little elevated at 20 hz.  My ears only register in this room to about 25 hz though.  It's weird, the drivers flap and I can sort of sense some pressure - the microphone says I have sound there but I sure can't hear it.  So, call it 2 1/2 octaves.

GM - I don't doubt that having the ST on a small network has some effect on the system as a whole.  They are directly wired together after all. 

Russell - The Bastanis design is cool.  They have similar design ideas to Zu, plus they were very early in the open baffle uprising, I hope to be able to check them out some day.

[Ed Schilling]

I think high excursion subs work simply because our ears are MUCH less sensitive to distortion at low freq.

Using large cone area is always better than excursion for low distortion bass but that does not mean it's better in a practical sense.
Hell, I build a high excursion bass augmenter! But I know better! But who has the room for a washing machine size cab!

The distortion of the Magnepan MMG was measured to be >10% @ 5o hz.........but people don't mind at all.

Try that number at 1-5K and see what happens!

Graham............we should talk some time in person! Have you analyzed all of the MTM speakers that don't come within a light year of Joe D'Appolitos original concept. Truly depressing.

And sorta along these lines.....look at the followup in the Oct 08 Steroephile on the Fried speaker. And then axe yourself how a company like Fried could screw up a crossover so bad. Then think how people who don't have a clue but get info from the internet to design them fare. I spent almost 2 years on a crossover (tweaking and finalizing) for a pair of (proper) MTM TL's. It was worth the effort and the end result was NOTHING like what I had calculated as far as xover point was concerned. And I did know what I was doing and even WHY I was doing it (just took my time at it, full time job and all). Keep that in mind when thinking of just sticking a coil and cap on a pair of drivers...textbook values are seldom going to be close and even LARGE, OLD companies screw up.

Single driver designs eliminate this but are actually harder to get right, I think.
 
Ed

[planet10]

...The Zu is a simple high pass... I'm honestly surprised more manufacturers aren't trying similar strategies.

This is a very common strategy... i've had dozens of commercial speakers that do this.

dave

[miklorsmith]

I meant the "whole design concept", not just the supertweeter hi-pass.

[macrojack]

Where would the Large Advent fit into this discussion? Many people seem to think it is one of the greatest designs ever and I believe it had a 10 inch woofer in a 12 inch basket with a complicated crossover and a tweeter. That's all.