[hurdy_gurdyman]

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

I agree that having published specs have their place. I think T/S specs are mandatory for any speaker being sold to the DIY community. Graphs are optional, being completely dependant on different companies philosophy. There are several companies that don't publish graphs because they can be mis-leading to the novice. I'm mearly pointing out that it is a legitament way of selling a product. All depends on how one looks at it. I have no doubt that the SI Coaxials response graph would hold it's own with most other single driver or coaxial speakers out there. However, almost any driver can be made to perform better than it's measured response makes it appear on a standard frequency response graph taken in an anechoic chamber. That's not my point though. I think the point is whether or not the speaker is aimed at the non-technical music lover who wants a simple, uncomplicated way to make an affordable speaker system or someone who pursues speaker building as a hobby. It's, in many ways, just a different sales philosophy. Come to think on it, it's an entire different viewpoint on audio in general. The tech person vs the straight music lover. The music lover with no technical skill can't make any use of a graph, anyway, so will only be confused by wiggly line that doesn't measure "perfectly flat". However, by reading about a product on a few audio forums and getting almost nothing but positave feedback will feel more convident to purchase something that he/she might otherwise be scared off from. All just a different philosophy.

Dave

[hurdy_gurdyman]

I dunno guys..
You're gettin' pretty complex here.
The whole idea of simple open baffle is just that - simple.

That's the main reason I took an interest in the Silver Iris. You just stick them on a baffle and forget about them. A speaker for the non-technical person who just wants a nice simple speaker that sounds good and covers most of the audio range without the real need to integrate a bass driver. Of course, with a bit more complexity, like adding the Augies and a plate amp, you can make things better, but it isn't mandatory to get really good sound.

I have the technical experience to design and build a rather complex speaker system, but my desire these days is to keep things simple and easy.

Simple is good!

Dave

[JohninCR]

Mark,

I'm in agreement regarding XO circuitry, however, I have nothing but ICs, amps, and
speaker wire between my DACs and drivers.  In the past, I couldn't even find a cap
that I couldn't hear even when used just to protect my low xmax drivers from LF signals.
Admittedly, I didn't spend a bunch of money on it.  This combined with parts not available
locally made me shun anything but single coils.  This minimalist by necessity approach
forced me to learn a lot and gain a better understanding of the effects of manipulating
the FR via changes in the physical construction including some things I don't think have
ever been done before.  Seeing graphically while listening to the effects of changes as
they occur has given me a newfound respect for those who design passive XO's. 

I'm not advocating the use of complex XO's or any circuitry.  The rapid bass roll-off of
the 206 due to it's natural roll-off in free air below 200hz, combined with the dipole roll-off
of the small baffle forced me to use a steeper filter on the Augie for them to properly
integrate.  I tried first order and it was a no go, even with EQ.

With the computer based active system that I'm using, the digital signal is delayed briefly
while the program changes it as directed.  Then it is output to the DACs.  While the XO's
do affect phase, just as any XO does, it also includes a program that corrects the phase.
Because this all takes place in the digital domain there is no corruption of the signal by
any electronic circuitry, so it's really no different than the sound engineer mixing the
recordings, just in reverse.  I start with multiple copies of the digital signal being routed
to all of the amplifier outs.  Each copy is filtered at my direction to the appropriate
frequency response to send for each driver.  Unlike player EQs and sound card processing
that I've tried in the past, I haven't been able to detect any adverse effects on SQ. 

I feel that the only compromise I've made with this minimal baffle approach is that there's
no way around another driver to augment the bass resulting in some loss of the single point
source sound.  To me the cleaner midrange from not forcing bass out of the full ranger,
offsets the loss of point source sound by a wide margin, with one being barely noticeable,
if at all, and the other being significant.

Last night I compared the B200 on a large baffle receiving an unprocessed signal to the dual
driver full processing approach and it was flat out no contest even with some simple acoustic
jazz.  I tried a few things.  EQ'g the single driver's bass up to a decent level, as well as
dialing in less bass for the dual drivers to match the unprocessed single driver, both resulted
in much better sound with the B200+Augie.

I agree that single drivers on OB can sound great.  Yes it's very easy to do and get great
sound.  That's what's made all of us fall in love with OB and we convert to the boxless
darkside.  It always leaves you wanting more though, because the bass isn't full enough.
I'm here to tell you that there's a darker side, and that's active and boxless.  It's going
from sound that's better than any boxed speaker, especially with certain types of music,
to world class sound that rivals the best stuff money can buy, with another simple leap
of faith into the darkness which brings out the best in your drivers and negates the worst.

For me, I can finally see light at the end of the tunnel.  I'll optimize a few different things
and decide on a set or 2 of speakers.  Then I can finally finish my office/HT/listening room
and work on my infrabass solution and be done.  Yeah right, then a new driver will come
out, plus there's amps to try. aa

[MJK]

You're gettin' pretty complex here.
The whole idea of simple open baffle is just that - simple.

I thought the whole idea of OB was an attempt at improved/different system performance by eliminating the box.  In most reflex speaker systems the box is what produces the bass, so you are throwing away a significant contributor to the systems sound.  By adding a second driver for the low end you are replacing the box contribution while still keeping things fairly simple.  Crossing over low retains the single driver performance aspects. 

Having now designed an OB system, and a slew of boxed systems, I have found it simple to find a working OB geometry.  By using an active crossover and two sets of drivers it is still very simple since you can adjust the final result by ear.  If you crossover point is low then the full range sound is maintained but with a stronger bass output which is really the Achilles' heel of most full range systems.  If you restrict yourself to a single driver, a flat panel, and no filtering in my opinion you have severely limited your systems potential and if anything it may be more complicated to optimize the design to provide great performance.  Please don't close doors and limit your results under the assumption of simplification.

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.

So you don't want a crossover with its associated caps, inductors, and resistors but you will except a series correction filter?  Seems to be a little inconsistent.  I have used correction filters on my TL's for years and have heard nothing but improvements if they are sized correctly.  No signal is lost in the process just the amplitudes of the different frequencies are rebalanced.  But by using a set of woofers for the very low end, I do not even need the correction circuit on my system so the amp is simply connected directly to the full range driver.

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.

I agree completely, when I fold the wings back on my OB system ( http://www.quarter-wave.com/Project07/Project07.html ) the bass response is compromised.  So if we extend that thought, for a given driver producing bass frequencies, the size of the baffle will determine the depth and volume of the bass.  An infinite baffle is one extreme and no baffle is the other.  You will get bass out of both extremes but the question is how much and at what frequency.  Running with no baffle is fine if it meets your performance goals.  I'll stick with a baffle.   

[mcgsxr]

Fascinating thread, mostly managed by those with depth in objective and subjective experimentation, and research.

I remain interested but unmotivated by what I read.  Interested because I am always looking for new ways that others are making themselves happy, and the closer it comes to open baffle b200 Visaton, the closer it is to what has held my attention for getting on 2 years now.

Unmotivated, because for me, subjectively, I have discovered (and remain a relatively lone voice in the wilderness around...) amp synergy as a phenomenal portion of the sound reproduction spectrum, specific to the b200 run full range, on a 40x30 OB, mildly folded - as in folded just enough to remain upright, so less than 60 degrees.

The posted FR curve for the b200 is exactly what it sounded like using a stock Teac AL-700P amp.  Mildly better with a fully modded Bolder Teac, or a lightly modded Vinnie Teac.  Better still using a Panny receiver or two I tried.  About the same using a gainclone.  Surprisingly MUCH better using a JVC EX A1. 

MarkC's mono amps were the first real revelation - I have posted about those amazing things before, but I am on a student's budget these days (mortgages and 2 kids will do that!).

Stunning sound using a 1950's Magnavox console tube amp - Class A, single ended pentode (el84).  Bass fullness, mid magic, nice highs (the highs could be improved in smoothness, but this is the b200 run wide open, on older caps - need to have those reviewed to really get this going I bet).

No X over, no smoothing circuit, no subs running (though they are installed in the baffles, since this is a total WIP, and the subs came before the amp).

Just simple full range b200 with amp.

So, should that stop the presses, and make this all less worthwhile?

Of course not, I am just one nut in his basement, that loves this sound. 

You are all pursuing what I (for me) have found.  Your versions are guided by your ears, in your environments, and in many cases by your objective natures.  I guess I am just a little more subjective (and I know that ALL of you do LISTEN to what you create) and am willing to play around in a different way.

Keep it coming, I love trying to understand where you each are taking it!

[Bob in St. Louis]

Here's my simplistic approach:
- Hawthorne SI on no baffle, or just a ring. Mounted to a 'stand', or tripod.
- Hawthorne Augie with some form of small baffle, possibly something like Brads (Gnat Leaders) Target bowls, but mounted to the back of the driver to help with bass. Also mounted to a 'stand', not a traditional wooden board type baffle.
- The legs of the SI would straddle the Augie making it appear that the Augie is sitting on very short feet sitting in between the legs of the SI.
- Then, they could be independently toed, tilted, or have their distance from seating position adjusted for imaging.
- No physical connection between the two drivers.
- The SI would be powered by the receiver, the Augie powered by a separate amp or receiver so the gain could be independently adjusted, or the Augie turned off completely for genres that don't require bass.

I haven't the knowledge, experience or cash flow to get "too fancy" with the set up. I'm so happy with the way the SI sounds right now, I have high hopes for the potential of my system when the Augie's come.
If I can be "90% of perfect" with that set up, with that kind of financial expenditure, I don't see myself spending a bunch more to gain that remaining 10%.

I'm all for simple.  Simple = Less money.

Bob

[Wind Chaser]

No baffle = No bass

The 15" Augie without a baffle can neither go as deep or sound as clean as the 8" B200 on a reasonable sized baffle. 

How do I know?  Been there - done that - sold a pair of Augies.

[nodiak]

I've always liked the 2 driver approach. Once you find a ~200 hz and up driver the rest is integrating a bass system with your room, to your tastes. This time around (was thrown off from the sport last season) I should be getting into biamping and active xo for the bass, maybe with some electronic eq. I've found for me in this room it's possible to do alot of the level adjustments physically via baffle size and placement on or off the floor. The room is #1 and each one has it's own challenges.
'86 -'93 was my speaker building heyday and one of the better ideas was using midwoofers in short tl's for ~150hz to the tweeter on top, and bass systems below. The mw tl's were typically 8- 16" sonotubes, somewhat related to uboxes. I'm enjoying how ob's have been an evolutionary advancement of this concept for me.
I might like the donut baffle idea for the main driver. But I think the bass driver will need to be "tuned" to each room according to it's response. Sure you can eq everything but not everyone's going to go that approach. I'll probably just go with Marchand xm-1 xo's and their stock gain adjustments and an amp.

I also very much agree with Mark about amp synergy. We're into the realm of favorite colors here, which is why I place the jvc ex-a1 behind the gc's   . Nearly everyone's got a steadfast favorite amp their system is built around. For whatever reason the gc's work well for me, just cleaner and quieter, solid presentation, good instrument seperation, satisfying tone. The jvc is good but soft to me, I use it for ht. If possible I'll try another tube amp later on, but I like the flexibility of the gc's large 50 watts.

Mark, is the pool table in yet ?

Don

[Bob in St. Louis]

No baffle = No bass
The 15" Augie without a baffle can neither go as deep or sound as clean as the 8" B200 on a reasonable sized baffle. 

Here's what I was referring to......



It's Brad's idea (Gnat Leader) for the FRONT of a driver, I was thinking about modding it to fit on the BACK of a driver.
Now, I realise it looks big, but imagine cutting a hole big enough for a 15" driver.
I'm picturing a more directed rear wave, like the pattern of a 3 foot long shot gun barrel (small spread) instead of a 'sawed-off' (wide spread).

Bob

[JohninCR]

mcgsxr,

I appreciate wanting to keep things simple, and I try to apply
the KISS principle to everything I do.  I reality your approach
is the hardest, most complex, and most expensive of all, because
your amp is your filter.  You are fortunate that you've found just
the right combination so quickly, and if you're done that's great,
more power to you.

I think you happened on addressing edge diffraction without even
knowing it.  The larger baffle lowers the frequencies of where
the transition occurs and spreading it over a longer baffle edge
reduces the magnitude.  Plus you have another benefit in the
shape of your baffle, which is the fold angle.  Since it is less than
90 degrees the transition is more gradual, which goes a long way
to eliminating the comb filtering that Linkwitz talks about.

I can't live with large baffles or I may have stopped long ago.
Now it's a hobby, so I'll probably never stop.  It goes hand in hand
with a favorite pasttime, listening to music, and my work from home
business.  Thanks to Hurdy_Gurdyman I lucked into discovering OBs.
It was rewarding right off the bat, because it's so easy to get good
results.  While Linkwitz generously shares all the science needed,
there was little precious little other solid information available.  That
gave me the feeling of being an explorer, which is very rewarding.
Whether or not everything I'm trying has been done before is irrelevant
to me, because I don't see them sharing, so I have nothing from which
to copy.  I'll stop only when I think I can't make it sound better, look
better (to me), or make it more room friendly (smaller).  In the meantime
I'm having a lot of fun.


Bob,
I spent right at $400 to explore my current avenue.  $250 for an M-Audio
Firewire 410 outboard professional sound card; $75 for a measurement
mic, mic stand, and cable (that I've yet to use, but soon); and $80 on
software.  I can now completely control up to 10 different drivers or
driver groups, and never have to purchase a single crossover component
or really learn the art of crossover design, so I'm sure it will save me $
in the long haul.  Plus, I believe it's a major step forward in terms of SQ,
making it a bargain for me right off the bat, and money better spent than
any set of drivers I've purchased.  On a budget someone could spend a
lot less on a sound card and forgo the measurement capacity and tune
by ear.  Of course you do need more than one amp.

[nodiak]

Bob, I've been thinking of smoothing the turbulence of the backwave too. Something along the lines of attention to laminar flow of vehicles. People have reported good results by fitting rounded pieces inside the basket spokes and smoothing out basket/magnet transitons. A cone shape over the magnet sounds good too.
Anyone have pics of such things? Probably best for a new thread?
Along with driver dampening I think this is part of the propriety custom techniques of some companies.

On topic...John, I'll check out your gear, I'm interested in the ability to dial in/contour response that way. Reali$tically I won't be buying anything for awhile tho, but I should keep up with the explorations.

Don

[JohninCR]

Bob, I've been thinking of smoothing the turbulence of the backwave too. Something along the lines of attention to laminar flow of vehicles. People have reported good results by fitting rounded pieces inside the basket spokes and smoothing out basket/magnet transitons. A cone shape over the magnet sounds good too.
Anyone have pics of such things? Probably best for a new thread?
Along with driver dampening I think this is part of the propriety custom techniques of some companies.

On topic...John, I'll check out your gear, I'm interested in the ability to dial in/contour response that way. Reali$tically I won't be buying anything for awhile tho, but I should keep up with the explorations.

Don

Hey Don,

It's been a while.  I hope you didn't make a surfing trip to CR without contacting me.

Where's that info on the basket mods?  I already have some dowels that I was going
to rip in half to do exactly what you mentioned, damp the basket and smooth the
flow at the same time.  I'd like to see how they did it.

[MJK]

I've been thinking of smoothing the turbulence of the backwave too. Something along the lines of attention to laminar flow of vehicles.

Flow?  How much motion of the air do you think is happening? 

It would seem to me that for OB applications, the oscillating motion of air associated with a sound wave is very very small for everything but a massive bass transient.  For general music (vocals, piano, acoustic instruments) the back and forth motions of the air have to be tiny, I am not sure you need to be concerned about laminar vs. turbulent flow.

[JohninCR]

Don,

Also, I've been thinking about your floor resonance problem after I noticed how much
vibration I get in the concrete slab near a big OB bass driver.  It's something I want
to figure out because one of the great benefits of OB is how well it stays in room, but
pounding vibration into the structure negates much of that benefit.

[JohninCR]

I've been thinking of smoothing the turbulence of the backwave too. Something along the lines of attention to laminar flow of vehicles.

Flow?  How much motion of the air do you think is happening? 

It would seem to me that for OB applications, the oscillating motion of air associated with a sound wave is very very small for everything but a massive bass transient.  For general music (vocals, piano, acoustic instruments) the back and forth motions of the air have to be tiny, I am not sure you need to be concerned about laminar vs. turbulent flow.

Martin,

My thought in this regard is for the full rangers with the stamped frames to make
the higher frequencies escape the basket structure better, reduce any reflections
from the basket back toward the cone, and damp the frame at the same time.
In addition, I'd think that anything to smooth the transition should be beneficial
because that sharp metal edge must be creating something similar to edge diffraction.
Is that thought process missing the mark?

[Bob in St. Louis]

John, I'm interested in your PC deal. It didn't sound "too awfully" expensive, plus it sound infinitely tweekable.(without buying more parts)

Don, the way I imagine the rear wave exiting the driver is aerodynamics. Just like a car.
That might be what you said when you wrote, "lines of attention to laminar flow of vehicles", but I'm not quite sure what that means.
Basically, just like a car, if it's a rough surface, sharp edge, or anything "not easy to flow around", it will create eddy currents. I've imagined a cone on the magnet, like a professional bicyclist helmet. I'd like to see driver manufacturers use a tubing, again like a high performance bicycle frame, tear drop shaped. That would be very aerodynamic.
Realizing of course there is no "air flow", but that air is pulsing back and forth very rapidly.
I would think nice radiused edges and corners would 'make it easier' for the sound waves.

Bob

[JeffB]

I appololigize for a being a bit off-topic, but I feel the need to complete my earlier post.
Last night I dropped my crossover to 75Hz.  This improved my mid bass dropout considerably.
Now I need some measuring equipment and I need to build a couple more baffles.
I have the polk mm6520 as the left channel and the B200 as the right.
I was hoping I could figure out which driver I liked better this way, but it is too difficult to tell which driver is producing what.

[MJK]

the higher frequencies escape the basket structure better, reduce any reflections
from the basket back toward the cone

I have seen the sound reflected back through the cone discussion before with respect to the coupling chambers of back loaded horns.  Personally, I don't buy it.  You can damp the frame and change the acoustic load seen by the back side of the driver's cone, which may or may not be beneficial, but in my opinion once you get wrapped up in diffraction from the sharp edges of the basket and sound being reflected back through the cone material you have reached a microscopic level of rocket science (really more voodoo) that is addressing minuscule details and ignoring bigger issues that will improve performance.  I think there are issues that are more macroscopic that would benefit from additional efforts and produce bigger improvements.

[hurdy_gurdyman]

the higher frequencies escape the basket structure better, reduce any reflections
from the basket back toward the cone

 I think there are issues that are more macroscopic that would benefit from additional efforts and produce bigger improvements.
[/quote]Martin,

Don't keep us in the dark, lets hear about some of those issues ideas!

Dave

[nodiak]

MJK, good point I can see there's little actual air movement that would need redirected. I'm just thinking of smoothing reflections, as minor as they may be. Of more importance I think would be the rooms nearby walls, and I'm looking at absorption and diffusion solutions for that. DIY diffusor: http://pmerecords.com/Diffusor.cfm
I think I have a common hobbyist habit of carrying over ideas from other interests, yes it's the little bit of knowledge syndrome. The laminar flow thoughts are from human powered vehicle shells (no I haven't built any, just checked them out). Good to know that that guitar riffs are likely not coming off the back of the cone at 65 mph...or at least for much distance if so...
The driver I have now for the 200 hz and up ob is an 8" Hemp. Very open basket design so maybe no concern there.  It has a whizzer cone which I've imagined could cause unwanted reflections. Any thoughts on this?
Don