[Acudoc]

I love this idea.  Keep it going guys.  Soon they will be burning all those boxes in the streets! 

Viva la revolution y la pura vida

Here's an idea for mounting the drivers

http://www.ergoindemand.com/pole_mounts_collection.htm

John

[MJK]

Greggo wrote several pages ago :

I guess it is also fair to say that most of us know about the whole wave-length versus pi radiation space and how that creates natural points for baffle-step work etc... and about edge diffraction, and also the path length for dipole cancellation etc... 

Do you mean roll-off of the driver's response at the low frequencies due to the baffle size?  I am confused about the use of the expression "baffle step", I associate baffle step with a driver in an enclosure at the frequencies where the sound field transitions from radiating into full space to radiating into half space and producing a 6dB increase in the SPL response.  I have not seen this phenomenon in any of my OB analyses.

[Bob in St. Louis]

John(acudoc):
You know, it's funny that you mention that. Because as I sit here at my desk in the service department of a car dealership, I'm watching a guy perform PDR (paintless dent removal).
He's working on various body panels getting the dents out. Now how can this possibly relate to audio/OBs you say? Well, he's got this dual bulb florescent light fixture mounted on a 'double jointed' wheeled boom. I'm sitting here imagining a driver mounted to that boom instead of a light.
It would be cool to have three axis flexibility when selecting optimal driver location.....
Although the noises created from the boom 'buzzing' would be hard to tame.
Sounds like a neat idea to me.
Anybody got any heavy duty pro style mic/equipment booms they'd like to mount a driver on?

Bob

[JeffB]

JohninCR,

Do you know how low the Silver Iris is playing with no baffle and likewise how high the Augie can go.

I have been experimenting with a B200 and an old Polk car audio coaxial the mm6520.
I placed the B200 in a 12" wide baffle and the frequencies rolled off way above my subwoofer.
So I placed 2 12" wings pointed straight back.  Basically a box without a back.  This is better in terms of frequency coverage, but still a little lean in the mid bass.

I placed the mm6520 on a 16" wide baffle.  This is also a little lean in the midbass.

I am currently struggling with getting enough bass in the in the lower midrange say between 80 Hz and 125Hz.  I am not sure of the exact range.  I need better measuring equipment.

I have strong bass from the subwoofer, but it is easy to hear a lack of midbass suppport.

I too desire a baffle that is not very wide.  Mainly because I just don't have room for it.

So the Iris and Augie are of interest to me, but I still worry about having this midbass dropout.

[scorpion]

Regarding the Silver Iris and the Augie we would be much better off if the manufacturer would publish frequency response, impedance and soundspread curves in a/(the) standard way. That would give much better possibilities to evaluate the drivers.

/Erling

[hurdy_gurdyman]

scorpion, 

What good would the published response graphs do? Many people on this and other forums have mentioned the the B200 driver doesn't sound anything like it's factory response graph. The same can be said of other drivers as well. Manufacturers typically measure speakers nearfield on an IB either outdoors or in an anechoic chamber, which won't sound anything like your listening room anyway. Worse yet would be inroom measurements. which would be even more mis-leading. A lot of people have been mis-led on a lot of speakers about how they actually sound by the published manufacturers graphs. What's really important is how they music reproduce music, which can't be represented by any graph. It either sounds good or it don't, and the graph won't tell you this. A perfectly flat graph doesn't mean it's going to sound great (or even just ok), while a less than perfect graph doesn't mean it won't sound great. The best way to get a handle on a speaker you haven't heard yet is to read what others who have heard or own it have to say. The more folks you hear from, the more convident you can be of a product. There is no perfectly "safe" way to buy a speaker and be sure you're going to like it. People's tastes vary, and seeing as there is no perfect speaker, we just have to go with what people with similar tastes have to say about a product and give it a try. It's a risk we all take. It seems to me that, over time, certain people seem to become more familiar and reliable to you on the forums, just as certain magazine reviewers become more trustworthy to you, and you learn to have more faith in their opinions. This does take time, but I can think of no other way that is as reliable to make a good buying desicion on. A product's reputation in the marketplace will, at least for the most part, determine if it sticks around. Bad sounding stuff don't get good feedback for long...

Dave

[Bob in St. Louis]

The best way to get a handle on a speaker you haven't heard yet is to read what others who have heard or own it have to say. The more folks you hear from, the more convident you can be of a product. There is no perfectly "safe" way to buy a speaker and be sure you're going to like it. People's tastes vary, and seeing as there is no perfect speaker, we just have to go with what people with similar tastes have to say about a product and give it a try. It's a risk we all take.

I stood at the edge of the 'deep end' for awhile, reading everyone else thoughts and feelings. After I thought I'd heard enough, I dove in.

Come on in, the waters fine!  aa

Bob

[Rudolf]

... but with OB's I find that edge diffraction is much more pronounced, but
I've been unable to engage anyone with more knowledge in that discussion.

I thought Linkwitz had explained that in depth: www.linkwitzlab.com/faq.htm#Q8

"... You might say this is a much stronger diffraction effect than for the closed box - and you are correct - but it is also the characteristic response of an open baffle, dipole source ..."

[JohninCR]

Jeff,

Your problem sounds like a phase issue related to the sub's XO,
unless you running the B200 with no correction.  Without correction
an augmenter needs to run up to several hundred hz with a low
order roll-off above that.  Try some different distances for the sub
or switch it's polarity to see if cancellation is the cause.  At those
frequencies, phase differences amount to feet not inches. 

Although I like to use wings, for a driver with as much HF in the rear
wave as the B200 I wouldn't do an open backed box unless you're
willing to sacrifice a chunk of the OB big open soundstage, because
you need stuffing back there.  Getting really good sound with wings
and no stuffing takes work, and I believe that it's essential to create
a continuous expansion from the driver cutout all the way to the
rear edge of the side panels.

Regarding how high do the Augies go:  With the SIcoax + Augies NoBaffle
I run the Augies with 8db of shelving EQ boost at my dipole room limit of
27hz.  Then a 1st order lowpass filter at 250hz plus a second order filter at
400hz.  I put a 1st order high pass filter on the coax at 100hz to keep its
excursion minimal for better midrange.  Listening to a tone sweep I came
up with 280hz as where the coax without a baffle starts rolling off, but
with 1/3 of the rear wave being reflected forward so early by the support
structure (the flaw I mentioned in my initial post) it probably goes somewhat
lower in free air. 

BTW, since yesterday I've been running a pair of B200's with Augies, and
with my computer driven active solution I'm finally getting some magic out
of them.  I having really taken much time to fine tune, but I have the same
settings for the Augie with the B200 on more baffle than the big coax, but
I did need to turn the Augie amp down a little due to the efficiency difference.
I'm EQ'g the B200s down by -4db with a Q of .6 centered at 2500hz, plus a 1st
order high pass set at 100hz.  I strongly recommend filtering out the lows of
any full range driver.  It results in a significant improvement in the midrange. 
The tech types have that right in their arguments against full range drivers.  I
just haven't found a clean way to do it until now, with my new toy that handles
all this stuff in the digital domain and is totally transparent.  I also get the same
improvement with my 3 sets of horns, so even if they can do it, full rangers are
better when relieved of low bass duty.  OB bass is the way to go to handle any
bass augmentation.  It's easy to integrate and the converse isn't true, integrating
boxed bass with OB is difficult, not impossible, but difficult.

Linkwitz's Fequal formula predicts a 306hz start of the dipole roll-off for a 15"
diameter circular baffle, and I'm still trying to reconcile the difference, since
according to theory it should be much higher because sound can't originate from
the center.  I believe it has something to do with the zone where the cone output
is still just a pressure front and changes into wave form.  The physical
behavior in this zone (sorry I forget the name) may be part of what gives us
consistently better bass extension than theory predicts for OB. 


Erling,

I agree with Dave.  I've seen the Eminence IB measurement of the Augies, and
it doesn't resemble even remotely the smooth results I'm getting in OB.  I'm using
mine up much higher in frequency than I thought I could.  As with any driver, it
just requires the proper filtering.

[scorpion]

Dave,

The Visaton actually sounds as it measures or perhaps even worse than their published graph. That speaker must be helped both by baffle surface and external equalization to produce its absolute best. But in the Visaton case we are, at least in Europe, helped by independent German measurements and tests for a lot of significant parameters including distortion. To qualify as a serious manufacturer I think that you should give potential buyers as much vital information as possible. I cannot se what the manufacturer should gain if not providing this information. Frequency graphs are good information. The tendency to do away with measurement for more subjective evaluation is perhaps more fun to read and hear but will not help the customer in the long run.

I have nothing against positiv or negative discussion and talk about speakers and designs for those speakers. Won't be objective though. And some of the discussion in the forums tend to be too 'one' voiced and therefore not of as much information as it could be.

/Erling

[JeffB]

Thanks JohninCR.

I don't currently have any way to EQ the B200.
I am thinking of buying a Behringer DCX2496.
I am interested in your computer solution.
I have an old car electronic cross-over that I am using. 

Putting the B200 in a box without a back is a very temporary solution.  The partial box clearly affects the drivers sound.  However, the driver was not very pleasing on a flat 12" baffle.  I need a way to get that midbass in there.  So currently, the evils of the partial box are better than no mid bass.  I still don't have enough mid bass though.

[scorpion]

John,

Your post is very interesting. Suddenly we are talking about detailed tuning of a speaker for which we don't have any frequency range specification. I believe that the Augie is a good speaker, but I still would like to see the measurements. I am not directly astonished that you can play it higher in frequency than what you thought and for the baffleless case you have to. And without sitting inside a U-, W- or H-baffle it will sound as good as it can. And it has to because it will have an impact on the soundcharacter of the speaker combo. From what frequency do you have the bass shelving ? Is the setup that from your first post ?

You can actually hear the magic of B200's fullrange. But I agree in your recommendation of taking the deep bass off them. In fact it is very revealing just to be able to send some low bass testtones on a speaker to see what happens. And imaging that you want to play other tones at the same time. 

/Erling

[JohninCR]

... but with OB's I find that edge diffraction is much more pronounced, but
I've been unable to engage anyone with more knowledge in that discussion.

I thought Linkwitz had explained that in depth: www.linkwitzlab.com/faq.htm#Q8

"... You might say this is a much stronger diffraction effect than for the closed box - and you are correct - but it is also the characteristic response of an open baffle, dipole source ..."

Rudolph,

Finally we're getting some real depth here in the OB forum, other that what coil and resistance to use on a B200 (I corrected mine in about 30 seconds at no additional cost, and the 30 seconds included listening to a few variations without leaving my position). aa

I went back and reread SL's explanation of diffraction, as everyone should, however, I believe there is more to edge diffraction than that typical baffle step explanation.  Maybe Olsen's work demonstrates that changing the shape of the edges can create a more gradual change in pressure, and that's what eliminates or greatly reduces the comb filtering.  I suspect that there is more to it because there is back and forth particle movement at the edges, and with OBs it is intuitively at greater velocity due to the + & - pressures on each side of the baffle instead of only one side as with boxes.  Maybe you or MJK can give us some more insight in this direction, because I strongly feel this is a compromise even in SL's Orions.

In my view, the cause of the comb filtering needs to be addressed in a no-compromise design.  If you use a rectangular baffle, all you do is average the effects of comb filtering, not cure it.  The shape of the edge cures it.  Olsen's work demonstrates this as reprinted on Planet10's website on page 17 of the Frugelhorn plans at http://homepage.mac.com/tlinespeakers/FAL/downloads/Frugel-Horn-v1-maps-091006.pdf .  My own experience in this regard using identically dimensioned baffles with different edge geometries proved to me through quite audible differences how important curing the comb filtering really is.  If edge geometry helps a narrow rectangular baffle to an audible extent, that tells me that spreading the comb filter isn't enough.   The logical progression is, that if you cure the comb filtering and whatever other problematic effects happen with 90 degree edges, then it becomes just fine to use circular baffles as long as you eliminate comb filtering with appropriate edge geometry.

What this all means to the average guy following this, is sorry but good baffles aren't so easy to construct.  Use a rectangular piece of plywood or whatever as your temporary baffles, but at the edges of your permanent baffles you need a good 3-4" or more of thickness and angled or better, rounded with a large radius.  The nice thing about this approach is that you get to listen to great sound, while you build something that is guaranteed to sound better because in the permanent baffle you've addressed edge diffraction, baffle vibration, flush mounting your higher frequency driver(s) etc, not to mention that the thicker construction adds travel distance for the rear wave that means fuller bass.  Then you get the satisfaction that the extra work paid off, since your finished product is audibly better.  You can't do that with boxes, at least not without alot of extra effort and wasted wood.  Test baffles can always be recycled.

[hurdy_gurdyman]

Erling,

I suspect more people have been disuaded from even considering the B200 because of published graphs than people willing to try them anyway in spite of the graphs. This is probably true of a lot of speakers, especially raw drivers but not restricted to them. Graphs that don't look ruler flat turn a lot of people away. We live in a world where specs seem to mean more than experience. I used to be a big spec person. However, through almost 40 years of being in this hobby, I've found that what you hear and what you measure seem to rarely match. Graphs just can't tell you what a speaker will sound like, and can, indeed, steer people toward a less musical sounding product. That's why I quit reading Stereo Review and High Fidelity back in the 80's. Some of the speakers I actually had a chance to listen to didn't live up to what was implied by the measurements. Same thing with tube amps. They don't measure well, typically, but can sound vastly better than inexpensive ss amp's graphs and measurements show. There is just no way to show how any component will actually sound from a graph. The sound (music) is what it's all about. Only by reading a lot of peoples experiences with a given product can one start to get an idea of what it can actually do for the music. If graphs were so important, tubes would just be an interesting side note in history, especially SET's.

Ever notice that the review magazines that rely on describing a component's sound are still around and going strong compared to those that relied mostly on measurements?

Dave

[JohninCR]

JeffB,

You may want to hold off on the Behringer if you can.  I waited 2 years
for something easy to use, since I'm just a non-geek computer user, but
I'm still trying to figure out and eliminate it being finicky at times before
I sign off on what I'm using.

[JohninCR]

Dave,

You hit the nail on the head.  I waited a long time to buy B200 and
did so despite the graph.  I probably would have done so earlier
without the graph.

[scorpion]

Dave,

A lot of myths are also alive. But you are right. Measurement is not near the whole thruth. I never said that. I bought the B200 because I read the forums and got the impression it was very good. When I first fired it up it didn't sound to expectations at all. Published measurements then help a lot and save time for you when you try to get it sound the way it should. 

/Erling

[JohninCR]

Erling's right from that viewpoint.  It may not help sell drivers, but it sure helps us
implement them.  I'm doing a head-to-head right now of the B200 vs FE206E, both
on small baffles.  The Fostex graph sure makes my work a lot easier.

BTW, after correcting each I have to give the 206 a slight edge to my ears.  The
corrected 206 is noticeably more efficient, so I can use a tube amp, and the extra
extension and slightly better detail are welcome.  The 206 is much harder to get right,
and didn't edge out the Visaton until I implemented the phase correction of the steeper
2nd order XO slopes I had to use between the Augie and 206.  Though harder to implement
the result is closer to a single driver sound.  I need to try boosting the midbass of the B200,
so I can use a 2nd order on it too.

The B200 is smoother in the treble even after notching out the peaks of the 206.  I
suspect this is due to the lack of a whizzer and the associated phase shift of that
mechanical XO.

I wouldn't recommend trying the 206 without similar flexibility of XO, EQ and phase shift
correction for the XO.  Getting the B200 right is a piece of cake in comparison.

I still need to measure and fine tune both before attempting to put them up against the
FE108Esigma on OB, since all I have to do is roll off its bass.   Then on the other end of
the spectrum is the big sound due to the big wave launch of the Hawthorne coax.  There
will be a 4 way shootout soon enough, but I think it will come down to different ones
better with different types of music.  All are excellent though.

I almost forgot.  There's a darkhorse in the stable.  I've got the Parker 98 drivers to bring
out for a ride on OB.  They showed real potential the little bit I played around with them
over a year ago.  The projects never end. aa

[Greggo]

Martin,

Regarding my mention of baffle step and a few other things back a few pages.... I have yet to invest in any measurement/analysis equipment (and probably wont until I go with either a full blown DEQX or computer based set up for DSP driver equalization, crossover, and room correction...) and have only run a fostex FE88ES-R on open baffles of various sizes and just listened by ear to the changes.  I think our use of the term baffle step is in sync and frankly never even stopped to think if it really applied to open baffle designs or not.  I threw those things out there only to reinforce my point that this thread is not about optimal SPL and bass efficiency but about just observing driver behavior as the baffle goes from small to smaller to zero... and that we all have, at some level or another, the understanding that this is not the way to go after flat frequency response and efficient generation of SPL, but we are instead (and I say we loosely as John is doing all the work!) looking for and at other things that we may find important enough to pursue.

Love your work by the way, have been a big fan for about a year now... would have tried my little fostex in a MLT a while ago but early listening impressions convinced me to not even try to get full range sound out of them, I am waiting for a chance to try mixing and matching with something else (maybe the silver iris 10" version of the augie if it ever comes out...) to take care of things from 200hz on down.

Regards,

Greg Jensen

[markC]

I dunno guys..
You're gettin' pretty complex here.
The whole idea of simple open baffle is just that - simple.
Start throwing x-overs of 2nd order in the mix and it defeats the purpose IMO. We want to hear the drivers, not multiple capacitors, resistors and inductors. They Do affect the final sound.
If you want a simple, very good sound from the B200, implement a 2 component baffle step and add a fast sub woofer capable of doing up to 180 hz well.
If you want decent mid bass from this driver, you need baffle width. This is more than apparent to me when I fold back the wings on my baffles.
This is of course my opinion, but I do believe it has merit.