dpaws said:
Insomnia and muppetry me finks... just because I don't receive an acoustic response doesn't mean the driver isn't still moving at the lower frequencies - hence I'd still get all the doppler effects from the FR driver regardless of what I could actually hear.
Digital XO's aside, is there really no other way than to put a cap in the signal chain?
dpaws said:
Roll-off from an OB is 18 dB/octave. This is made up of the driver's 12 dB/octave and the baffle's 6 dB/octave roll-offs added together.
I would not count on a lot of room gain at the low frequencies. You will get a dB or two of reinforcement between say 80 and 100 Hz due to nearby room boundaries, but not a constant several dB below some specific frequency.
Telstar said:
The T/S parameters are intended to characterize the small signal response of a driver at frequencies near resonance. Why are they insufficient for that purpose? If you try and do something beyond what was intended it is not the T/S parameters deficiency that produces errors, it is the improper application of them.
rjbond3rd said:
OK, OK, I should have qualified my statement by saying, "Without physically modifying the driver."
Telstar: T&S parameters allow exact prediction of bass performance - so exact that measurement is generally only needed to confirm the prediction. Once the drivers are made, loudspeaker system design is no longer an art, it is engineering, and the essence of engineering is that it is predictable. As the Hitchhiker's Guide said, "Anything else is therefore your own problem."
Is it possible to use a Trusonic FR-80 in OB crossed over to a woofer at 200hz? I have a set of FR-80's and a set of Jensen woofers from a pair of defunct Rectilinear III's. They are both paper cones that seemed to be of similar make and they could tonally blend nicely together.
Is the QT of the trusonic irrelevant when crossed between 100 - 250hz? I'd like to build a 3 way with the jensen doing 200hz and under, the trusonic doing 250 - 6000, and a selenium compression tweeter doing 6000 and up. Is that blasphemy?
I guess my inspiration is the Volti Vittora for the woofer, while front loading the trusonic in ob and the horn loaded selenium compression tweeter.
Is the QT of the trusonic irrelevant when crossed between 100 - 250hz? I'd like to build a 3 way with the jensen doing 200hz and under, the trusonic doing 250 - 6000, and a selenium compression tweeter doing 6000 and up. Is that blasphemy?
I guess my inspiration is the Volti Vittora for the woofer, while front loading the trusonic in ob and the horn loaded selenium compression tweeter.
I can't imagine enjoying that regardless of the enclosure or lack of.
Reminds me of OEM 6X9 speakers on the back deck of your average NA car of the 60's thru 80's.
Just how hard are you going to try to make an underdamped driver sound good?
These are the TSP for the FR80:
Thiele-Small parameters for Trusonic?
Qts=0.546 and Fs=65 Hz. 250 Hz is about 4x65 Hz
Look where the line for Q=0.5 meets the w/w²=4.00 value: Q is 1 dB down from its nominal value - no problem with that. But you need to make the baffle large enough to support 250 Hz. Try it in EDGE.
Thiele-Small parameters for Trusonic?
Qts=0.546 and Fs=65 Hz. 250 Hz is about 4x65 Hz
Look where the line for Q=0.5 meets the w/w²=4.00 value: Q is 1 dB down from its nominal value - no problem with that. But you need to make the baffle large enough to support 250 Hz. Try it in EDGE.
thanks and sorry
Sorry guys for not responding soon enough. I got crazy busy and forgot about my post ( I need to get notifications set up).
My idea was to combine the FR80 with a tweeter in OB. For the low end I would like to mate those two drivers with a 12" woofer in a bass reflex cabinet.
My crossover points are 200hz and 7khz or 9khz for the tweeter. I have had trouble finding an appropriate tweeter that is 97db. I did find two candidates in the selenium compression driver at 100db or the peavey ribbon tweeter (both from PartsXpress ), but I don't know anything about their performance.
Sorry guys for not responding soon enough. I got crazy busy and forgot about my post ( I need to get notifications set up).
My idea was to combine the FR80 with a tweeter in OB. For the low end I would like to mate those two drivers with a 12" woofer in a bass reflex cabinet.
My crossover points are 200hz and 7khz or 9khz for the tweeter. I have had trouble finding an appropriate tweeter that is 97db. I did find two candidates in the selenium compression driver at 100db or the peavey ribbon tweeter (both from PartsXpress ), but I don't know anything about their performance.
Thanks for the measurement specs for the the driver. I think that since it measured at 94db matching a tweeter will be easier. With the qt at .54 I think OB will work fine.
Does anyone have a suggestion for a good tweeter in the $20 - $40 range?
Also, how many tube watts would I need to driver the FR80 and a tweeter in OB for 10' x 20' room?
Does anyone have a suggestion for a good tweeter in the $20 - $40 range?
Also, how many tube watts would I need to driver the FR80 and a tweeter in OB for 10' x 20' room?
Hey Vaughn, I have enjoyed this discussion and learned a bit from some people much smarter than I. Like you, I have no test equipment so I play around just to see what things will sound like.
I have a very cheap experiment for you. Get a nice big cardboard box, a box cutter and some screws. Make a couple OB configurations with cardboard and try your speakers. Really you are out nothing but time and really a hobby is about self discovery. You might learn something and have some fun along the way.
If it were I and I wanted to get serious right away I think I would start with a piece of cardboard about 2.5 feet tall with wings folded back and angled back so the angle projects the sound to ear level at your listening chair.
Then I might try a something taller and play with that a bit. It would be a great snow day project.
I have a very cheap experiment for you. Get a nice big cardboard box, a box cutter and some screws. Make a couple OB configurations with cardboard and try your speakers. Really you are out nothing but time and really a hobby is about self discovery. You might learn something and have some fun along the way.
If it were I and I wanted to get serious right away I think I would start with a piece of cardboard about 2.5 feet tall with wings folded back and angled back so the angle projects the sound to ear level at your listening chair.
Then I might try a something taller and play with that a bit. It would be a great snow day project.
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