Austin 166's in Austin

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I built a pair of Ron's Austin 166's and now that I have a few pictures and some measurements I figured I should post.

They sound phenomenal. I previously had these FE-166s in a BK-16, these trounce them in every way.

pics
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and
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Measurements (done with Room EQ Wizard and a RS meter with a replacement panasonic electret and some modifications):

This is L+R average then 1/3 octave smoothed. The 80-100HZ dip is purely a listening position problem. Listening position is compelled to be in the middle of a ~20*25 room thus the null of the 2nd harmonics 80-100. I don't know about the 700-900 dip...moving the mic lessened it and moved its center slightly but never fully removed it.

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Note the 43hz extension. The RCH which is loaded into a corner gets smoothly to 40 and then rolls of smoothly. The LCH loads into a hallway and drops off quickly after 45 hz.

I'm impressed...the extension of a MLTL without BSC and with all the dynamics of a BLH. I havent yet built the triangle reflectors...currently using a footlocker as a substitute in the RCH.


Sean
 
Thanks for the compliment.

The design is the Austin Rev G designed by Ron (who also designed the A126 and the Dallas). It can be found at:

www.FullRangeDriver.com

There are a few threads on it.

The plans are in the gallery there under "Austin Rev G BLH for Fostex FE166E driver". Ron suggests a few alteration's from the plan. One is the trapezoidal baffle that you see (though it should have 2inch extensions trailing backward that I haven't doen yet), its taken from the Austin II (you might find the plans under layertone austin on the fullrangedriver forum- not the gallery). The other is detaching the rear triangular prism deflectors, which I have yet to build.

Sean
 
I've also built a pair of these - without the extended baffle and with just one bass reflector for now.

They sound delicious and the bass is definitely there.

Next job is to build the second bass reflector and put both speakers on marble slabs - I have partition floors and the speakers are still shaking the floor by the listening seat...

How are you going to finish them? I used shellac which was far too much work...

Steve
 
I think I remember seeing pics of yours up on fullrangedriver a while back. I used shellac on my previous cabs, these have much more surface area and I think I'll do a simple wipe-on poly.

I have been having vibration issues with everything on the back wall, and my turntable on the sidewall. Now I need to build a decent turntable base :).

Sean
 
Glad ta be here. I had real problems with my last puter and linking to this forum. But the last puter died of virus content.
The new puter has no problems. Only problem is i lost the majority of my CAD files, so i have been attempting to re-create the designs. I did not lose the acoustic programs however.

On the A166, i would recommend the supra baffle (name coined by Dave) and the deflectors to achieve proper performance.
ron
 
I had some friends over tonight and listened to Calexico's "Things fall apart." I never did enjoy the last track until I got the extension that these provide.

Ron, I was wondering according to your model what should be the max SPL at x-max in the 40hz area with corner loading? I have been shocked by the cone control and concomitant bass SPL that these are capable of.

Sean
 
> I have been shocked by the cone control and concomitant bass SPL that these are capable of.

I'm still shocked by Ron's Austin IIs!!! The cone barely moves and the lows are very present - very perplexing because the cone movement doesn't really match the big output! Absolutely addicting & mind-boggling!

Working on a "layertone" version of the Frugel, really want to build another Austin II; think this time it'll be painted

Thank you Ron (repeating myself again)!



Tony
 
It's great to see you here Ron.

I wish you luck with rebuilding the cad files. It sounds like a lot of work, so I hope it all comes back without too much trouble.

The Austins really do sound great. I think my biggest problem making the bigger baffles is going to be living without them for a few days while I route out the existing baffles and redo the wiring. Not sure how I'm going to manage with the silence.:whazzat:

Steve
 
Ron, I was wondering according to your model what should be the max SPL at x-max in the 40hz area with corner loading? I have been shocked by the cone control and concomitant bass SPL that these are capable

Well, lets put it this way. Using wall floor loading and the deflectors the Xmax limit should peak at the average FR for that SPL in the upper frequencies.
If the drivers are rated at 94 db/watt/meter then the xmax limit will be reached at that point when wall/floor loaded. However greater loading via the corner will change that and i never ran sims for that condition. I never really sim for corner loading as that is a variable of the room dimensions.

The FR curve that zozo ran is very close to my calculations when both horns are wall/floor loaded.

ron
 
Here are Ron's plans:

http://fullrangedriver.com/gallery/albums/userpics/10044/Austin1.pdf

http://fullrangedriver.com/gallery/albums/userpics/10044/Austin2.pdf

http://fullrangedriver.com/gallery/albums/userpics/10044/Austin3.pdf

http://fullrangedriver.com/gallery/albums/userpics/10044/Austin4.pdf

Notes:

1) The baffle is not present in these PDFs. It sould be 12.7 inches square, ~2.1 inches thick (3 layers of 3/4 ~ 2.1 inches) with a 45 degree bevel and a 2 inch extension around the perimiter facing rearward. (Added benefit, the remainders from the baffle beveling can be trimmed to make the 45 degree cleats in the first bend of the horn)

2) The second bend in Austin1.pdf has an error it should according to Ron:
"I looked at the orig dwgs. Start of second 180 deg bend is 4.05" middle is 4.46" end is 4.72". This is the calculated expansion for that distance.There should be no "hump"."

3) It is convenient IMHO to construct the speaker and the deflector as two seperate peices. This adds one issue, the speaker becomes slightly front heavy with the driver and baffle sticking proud of it, I added a few inches of base sticking out to the front (with a slight .25 inch bevel to match the general look).

4) Getting the peices of the horn as accurate as ron plans is difficult. I had no difficulty with getting the side I drew the plan on matched up but getting absolutely perfect 90s is hard on some of the interior peices. An error of 1 degree is .13 inches. I would recommend cutting spacers of the exact width of the gap from the leftovers of the stuff cut to 7.9inch width (cut this all at once!!!) at different places (i.e. the throat and the bends) and clamping them in there while gluing to be certain of the geometry.

Sean
 
Sean, i have been developingmy baffle programming and i noticed that there is a high degree of probability that the 900 Hz dip could be caused by forward edge diffraction. If the trailing edges are installed this could eliminate the dip.

I am seeing some interesting things in the above programming. Even OBs have a very apparent edge diffraction. If you look at an OB as a horn with zero length and no acoustic gain then the end result is very near the same. What i mean to say (and doing a poor job at it) is on the positive wave launch(displacement is positive on the front of an OB and negative on the rear) the positive wave has more energy at the edges than the negative wave, then the action reverses as the cone moves180 degrees according to the sine point. This is a dual type edge diffraction as on sims that i have made a negative wave has the greater energy(partical mass concentration) in the center and falls off faster as the angle increases from the centerline than a positive wave launch of a transducer ( the OB being considered as a secondary transducer).. I believe i wrote a short artical about this observation in the FR articles forum.
I dont know if i am making myself clear on this action? Simply stated , an OB has more constant energy arriving at the edges than a normal box enclosure due to the fact that the dipole action is being produced on the same plane.

Conclusion: If an OB has a greater edge diffraction possibility then rounding of the edges will have a positive impact on the end result. A 3" OD piece of PVC with a slot cut down the length , to fit to the thickness of the OB panel ,would be a good place to start.
ron
 
What i mean to say (and doing a poor job at it) is on the positive wave launch(displacement is positive on the front of an OB and negative on the rear) the positive wave has more energy at the edges than the negative wave, then the action reverses as the cone moves180 degrees according to the sine point. This is a dual type edge diffraction as on sims that i have made a negative wave has the greater energy(partical mass concentration) in the center and falls off faster as the angle increases from the centerline than a positive wave launch of a transducer ( the OB being considered as a secondary transducer).

Ron,

Are you saying that a source oscillating with a symmetric sine wave type of displacement, will produce a pressure at the baffle edges that deviates significantly from a sinusoid due to unequal "wave launch"? The compressive half of the cycle behaves differently compared to the rarefication (spelling?) half of the cycle as seen from some listening position away from the source be it the baffle or the driver? If you are indeed saying this then I am having a hard time with the concept. I would have to believe that if this is a significant nonlinear contribution to the sound that the distortion produced by this nonsinusiodal action would overwhelm any good musical reproduction obtained by linear theory. How big are the deflections, pressures, or velocities that you are simulating? Are they consistent with typical listening SPLs?
 
Well Martin my simulation software i have been developing is based on hydrodynamec principals with an adjustment for the mass/desnity of air density at sea level.
The effect is a more vortex action whan the cone moves inwards, When there is a positive displacement the full effect of the baffle is affected..

Are you saying that a source oscillating with a symmetric sine wave type of displacement, will produce a pressure at the baffle edges that deviates significantly from a sinusoid due to unequal "wave launch"? The compressive half of the cycle behaves differently compared to the rarefication (spelling?) half of the cycle as seen from some listening position away from the source be it the baffle or the driver? If you are indeed saying this then I am having a hard time with the concept. I would have to believe that if this is a significant nonlinear contribution to the sound that the distortion produced by this nonsinusiodal action would overwhelm any good musical reproduction obtained by linear theory. How big are the deflections, pressures, or velocities that you are simulating? Are they consistent with typical listening SPLs?

What i am stating is there is a greater pressure near the edge of a baffle when there is a positive pressure applied. This pressure becomes an edge diffraction issue as the edge appears to become a secondary transducer with less energy.

I keep seeing the negative ( cone moving inward) as a centered spiral towards the center with less energy at the edge of the baffle. Whether it would deviate in a significant manner or amount will require more study, however, its there.

I keep seeing the same result, as the cone moves inward on a plane the action resembles the flushing of a toilet ( crappy analogy) as a vortex is formed which means more energy in centered around the piston and less energy on the plane surface away from the centerline of the transducer than a positive stroke.

How big are the deflectors, will i sim from 32" to 10" and the results are the same ( disregarding attenuation).

Any wave travelling over a surface that ends upon an edge will produce a secondary action that i consider as a secondary transducer. This secondary transducer will produce a later timed and less energy production than the primary.

An OB can be considered as a secondary transducer with the effective area being a launch platform for a given frequency.. As i have stated there is a differential in pressure at the edges at different sine points so therefore on a dipole action with the same given plane there has to be a greater total edge diffraction result than a singular plane action.

In hydrodynamics if a piston moves inward there is a vortex formed, if the piston moves out then the energy is spread over a greater area.

ron
 
Ron,

I understand the secondary source analogy at the edges of an OB or the edges of an enclosure, I have progammed this in my MathCad worksheets for both OB and any of the box rectangular geometries I have made available. What I cannot understand is how positive and negative displacements of the driver could produce anything but equal and opposite responses at the edges, which is what I think you are implying. If we are talking small deflections in air, I have to fall back on the response at the edges (or anywhere between the source and the edges or beyond the edges) being equal but opposite for a driver moving forward out of the baffle compared to backward into the baffle. This is what the science of acoustics is based on and every textbook I have on my shelf uses this feature as a fundamental building block for deriving all of the relationships presented starting in the first chapter. If I undertand what you are saying your model produces results that are nonlinear, do not satisfy or allow superposition, do not fit into the Fourier theory of series expansion or transforms, and are not governed by any of the wave equations (small oscillating motion of air) I have ever seen derived. Do I understand what you are saying correctly and is that what you believe is really happening? I would be extremely surprised if "hydrodynamic principals" did not reduce to the basic wave equation if the correct simplifying relationships were used to remove non applicable terms in the equations.

If I have paraphrased you correctly, and I step back from the very complicated math you are obviously doing, does this make physical sense on a very fundamental level? I have to admit I have my doubts, not that my opinion really matters. Can your method reproduce curves of baffle defraction response similar to the classic (measured I think) curves in Olsen's acosutics text as a sanity check? My MathCad worksheets can with what sounds like much easier math.
 
On perfection

There is none, i was just in Audio Asylum and there was an answer to one my quotes from here that i had to be wrong as Nakoda(sp) could not be wrong.

This is one sided thinking, and shows no expansion of thought, In any endevor there is an advancement of information and technology application. If there wasent we would still be driving cars with carbs and not computer controlled fuel injection and exactly timed spark.
The principals that were laid down by the greybeards are subject to change as technology advances greater defination occurs, nothing is ever written in stone and even physical principals (or the reasoning behind them) can change.

Every aspect of any field of physics changes to adapt to new learning and greater analytical power. If it didnt we would still be thinking that if you sailed too far on an ocean you would fall off an edge.

I have no doubt that when i publish my final findings that some smart young dude will come up with the proof that i was full of it and prove me wrong. I would be dissapointed if this didnt occur.

Its called "progress".


I will get into this in greater detail when i have the opportunity.

thanks
ron
 
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