Humble homemade Optimo loudspeaker

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Hi
Mine are still stuck in bass reflex cabinets, and therefore have not reached their full potential yet.
The wood is ordered for the TL cabs, but I am away for a few weeks, so I can't envision completing them imminently.
I am interested to hear other's views also.
Michael
 

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Thanks for response:)

Firstly I though putting the SS 8531 driver into 32 L BR cab, like SP95/98 from Troels site, but then I heard a lot of opinions on BR designs that are all very similar to yours "dublin78". So I though to go TL to avoid "loudness" effect in BR box.

Dublin78 have you tried Troels series crossover from his SP95/98 design on your A.O.S. project?
 
No I have not tried Troel's crossovers yet. I don't know that Tony's is not optimal yet.

The most surprising difference with the TL is aparently in the midrange. This is what I am hoping will be improved the most. Any change in bass behaviour will be incidental.

Planet 10: Tony's designs are well respected generally, so why don't you agree with his point of view? I can understand why you may disagree with the theory behind the Optimos, but the design was more largely based upon listening tests by an experienced designer.
 
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dublin78 said:
Planet 10: Tony's designs are well respected generally, so why don't you agree with his point of view? I can understand why you may disagree with the theory behind the Optimos, but the design was more largely based upon listening tests by an experienced designer.

In the last 7 years with MJKs modeling software & innummerable builds from it, the short-comings of classic TL design have been hi-lighted. This box may well sound fine, but i can't help but think it could be better. No consideration (or understanding) of how to get an appropriate length is documented, the cross-section is far smaller than would be usual for an optimum TL, and the semi-arbitrary offset of 1/3. For a 1:1 line the starting point for optimum is 0.349 and inches can make a difference.

dave
 
Planet 10: I completely understand your point of view, and your answer was expected.
Are your concerns largely about optimising the bass performance, or does TL theory affect the midrange also?
From reading Tony's build diary, it appears that he has made a deliberate trade-off.

For now, I will be building to the existing specs, but it would be interesting to build some tests cabs to a modelled design at a later stage to see what can be achieved.
 
supernet said:
Hello.

I searched the forum and see that here should be few Optimo TL builders.

I am also interested in this project, so could please anybody who build it or heard it describe sound a little bit?

Thanks

I built the optimo. My listening gave a sound with an open midrange and a very fine smooth treble .
The basses are very present and articulated. In comparison with a br that I also tested the midrange win in detail and opening. A speaker with a lot of smooth and spatial image amazing. I think that sings as well as Gamut L5.
 
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dublin78 said:
I completely understand your point of view, and your answer was expected.
Are your concerns largely about optimising the bass performance, or does TL theory affect the midrange also?

The theory considers only the bass, but experience says the bigger cross-section will help the mids even more. The better "total" function of the TL the better the mids. As i've said for 25+ years -- a good TL sucks the backwave down the line so that it won't come back thru thr cone.

It should also be noted that in Tony's empirical tests, the lines were not "tuned" the same. The tapered TL would need to be both shorter, and the offset would have to be different to maintain the same tuning. Tony 's experiment changed at least 3 variables at once which would have changed the ripple signature.

dave
 
Indeed.

Like Dave, I have a great deal of respect for Tony, and I don't doubt that this design sounds decent enough. But I'm equally certain that more can be extracted from these drivers, as there is little consistancy, or science apparant in the cabinets tested. Quite the opposite in fact, as noted above.

Using George Augsperger's or Martin King's alignment tables would allow a far more capable cabinet to be created. The two sets of tables BTW correlate well, though Martin's are more detailed & refined in proportioning the line itself and are freely available on his site -see www.quarter-wave.com

FWIW, I'd probably use a 3:1 taper line, tuned to 35Hz, driver offset of 0.336 length, with Vb in proportion.
 
Tony Gee is far more on the "listening results" side than on the scientist/mathematic side of the speaker design. IMHO designing a "strange/uncommon/mathematicaly more or less wrong" type of acoustical driver loading is part of our fun, at least mine. Optimo is such a design. I never listened to them...but I used the idea of a large constant cross section on a TL using a small Tang-band driver. The result in "openess/airy sound" was impressive and certainly not accurate :bawling: ...but far more enjoying than a classical Bass-reflex or small x-section tapered TL. :)
This quote summarizes what's the real trade off of the Optimo design:
"From these six different cabinets I have chosen the TL with a constant cross-section. It proved a nice balance between deep bass, open midrange and dynamics. After these experiments I also feel that a TL with a constant cross-section will work best for a 2-way design due to the more open and direct midrange and that a 3-way TL with a separate midrange driver would work better in a tapered line due to the subjectively deeper and tighter bass.";)
 
Re: Re: Humble homemade Optimo loudspeaker

Seems it is all about compromises. Yo don get something for nothing;)

anatole51 said:
I built the optimo. My listening gave a sound with an open midrange and a very fine smooth treble .
The basses are very present and articulated. In comparison with a br that I also tested the midrange win in detail and opening. A speaker with a lot of smooth and spatial image amazing. I think that sings as well as Gamut L5.


Anatole, do you use Hawaphon for damping?
 
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crazyhub said:
I also feel that a TL with a constant cross-section will work best for a 2-way design due to the more open and direct midrange and that a 3-way TL with a separate midrange driver would work better in a tapered line due to the subjectively deeper and tighter bass.";)

He doesn't have the data to support that since mot only did he change from a constant xSection to a tapered one, he changed the line tuning to a lower frequency & changed the way the ripples cancel from the offset. Was the improved midrange from the change in taper, or from the different ripple signature... or did the higher tuning do it?

Improved midrange is likely from a better ripple signiture than anything else... and it could likely be improved on at the same time as getting more bottom.

dave
 
Agreed. There's nothing subjective about it either, though the plots show little, primarily because of the shaky methodology used. A tapered TL is tuned lower for a given line length than a straight line. A tapered line also reduces harmonic ripple, which can be further attenuated by using the optimal driver offset.

Watch this. ;) 'ear we have a straight line, 74.7in long (gives 45Hz tuning for a straight pipe), the driver mounted as close to the end as possible. I haven't added any damping to these models, so you can better see what's going on in the pipe. The driver's just the default Focal unit BTW as all I'm doing is a general illustration.
 

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Perhaps, in the interest of furthering "science" someone could design a suitable enclosure using the software tools available and send them to Tony Gee. Then Tony Gee could build that enclosure and compare them with what he has built.

This of course would only work if all parties are interested.


Andrew
 
This is fascinating stuff. It has re-awakened my enthusiasm for this project, and I can't wait to crack on when I get back from my holidays.

I am going to use a laminating technique for the build using 24mm BB ply (with the all the edges of the laminates facing forward). I will be using 50mm thicknesses on all dimensions except the sides, which will be 24mm due to the thickness of the ply. If I used two sheets for the sides, either the baffle would be too wide, or the driver "breathing" would be compromised on the inside.

I cannot get hawpathon in the UK, and it is frighteningly expensive anyway. I have bought 5mm acoustic damping sheet instead. It is 10kg per square meter. See http://www.cmsacoustics.co.uk/Industrial-Datasheets/2001 WB Acoustic Barrier.pdf
 
Perhaps, in the interest of furthering "science" someone could design a suitable enclosure using the software tools available and send them to Tony Gee. Then Tony Gee could build that enclosure and compare them with what he has built.

I would probably be happy to do this (the cabinet build, not the modelling, as this is beyond me) once I have built the originals (and have some spare time of course).
 
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