Still nothing on any of the transducers recommended to date.
I have a Web site where I look at "state of stock" and display what I call high resolution testing.
What George is talking about is sharing IR data. What he sent me was three IRs of his secret transducer modification project. Do you remember asking me to guess what you were doing? While I did not do that, I did talk to you about some strange errors in you IR response. Particularly that the data was not minimum phase.
I would gladly share an IR file with you George. If there is a transducer listed on my Web site that you would like to see the IR for, I will gladly send. I assume you still have my e-mail address.
Otherwise, as stated over and over I have both published and shared the results of my attempts at independent verification. One reason you publish is so you don't have to repeat yourself endlessly. I have also published numerous blurbs about transducer modification where I present classical comparative data (before and after) at high resolution.
I, at least, am still open to the possibilities. I have just asked that people try to verify the predictions made by the design models they use. Not much to ask for. Proportional response people. It is a good thing.
More on topic. Some idea of reference might include project performance boundaries or limits. For example, how loudly will it play.
I am using a three-inch transducer as a reference but am not recommending it for use here.
The transducer sensitivity for one watt one meter is 87.2 dB. Qts is 0.6326. Fo is just under 110 Hz and was verified by measurement.
Maximum average power is 12 watts for this transducer. Now, by measured verification I know that I can easily produce a small and simple enclosure that will produce an F3 of 120 Hz with no ripple. I also know that the manufacturer sets max cont power by distortion. When distortion reaches 5% at Fo that is max cont power.
Now, 5% is a little too high for me, but I will tolerate 3% at max cont power. While this is still arbitrary, since my F3 is 120 Hz, that is the frequency I am interested in. For this transducer, 3% F3 is reached for 10 watts continuous in at 120 Hz. One meter output is 97.2 dB.
Ten watts in at 120 Hz requires an excursion of 4.5 mm (or 9 mm peak to peak). This exceeds the transducers Xmax rating and is in part the cause of the distortion rise. This is, however, well within suspension max.
If you want to push the transducer to rated cont power max, then one meter output goes up to 98 db and 3% distortion point will be found at 122 Hz. Not far above the 120 Hz f3 point.
The transducer is also rated at 25 watts peak input. For this input, we produce a one meter sound level of 101.1 dB. Three percent distortion is pushed upward to 162 Hz.
What does this do for us? If this sound level (adjusted for how far away from the loudspeaker you sit) is acceptable, then one possibility for a very high performance system would be to cross at or a little above 120 Hz. Cross to a woofer or sub woofer system. An easy way to put one together would be to use a plate amp. There are affordable plate amps with fourth order low pass filters.
In a sealed enclosure the three-inch will acoustically roll off at 12 dB per octave. At a second order high pass filter and you will have symmetrical slopes. Preserve polarity. At fourth order, you should have acceptable to excellent stereo imaging. But you do not just have to take my word for it. If you decide to try this option you can verify or disprove it yourself.
If we use the plate amp, then it will be easy/simple to MFB the woofer. I suggest the simplest technique. I suggest not trying for more than 6 to 10 dB of feedback.
There is still work to do. We haven't come any closer to being able to rationally suggest a set of transducers at various price points to use in the project, regardless of the low frequency enclosure type.
I have a Web site where I look at "state of stock" and display what I call high resolution testing.
What George is talking about is sharing IR data. What he sent me was three IRs of his secret transducer modification project. Do you remember asking me to guess what you were doing? While I did not do that, I did talk to you about some strange errors in you IR response. Particularly that the data was not minimum phase.
I would gladly share an IR file with you George. If there is a transducer listed on my Web site that you would like to see the IR for, I will gladly send. I assume you still have my e-mail address.
Otherwise, as stated over and over I have both published and shared the results of my attempts at independent verification. One reason you publish is so you don't have to repeat yourself endlessly. I have also published numerous blurbs about transducer modification where I present classical comparative data (before and after) at high resolution.
I, at least, am still open to the possibilities. I have just asked that people try to verify the predictions made by the design models they use. Not much to ask for. Proportional response people. It is a good thing.
More on topic. Some idea of reference might include project performance boundaries or limits. For example, how loudly will it play.
I am using a three-inch transducer as a reference but am not recommending it for use here.
The transducer sensitivity for one watt one meter is 87.2 dB. Qts is 0.6326. Fo is just under 110 Hz and was verified by measurement.
Maximum average power is 12 watts for this transducer. Now, by measured verification I know that I can easily produce a small and simple enclosure that will produce an F3 of 120 Hz with no ripple. I also know that the manufacturer sets max cont power by distortion. When distortion reaches 5% at Fo that is max cont power.
Now, 5% is a little too high for me, but I will tolerate 3% at max cont power. While this is still arbitrary, since my F3 is 120 Hz, that is the frequency I am interested in. For this transducer, 3% F3 is reached for 10 watts continuous in at 120 Hz. One meter output is 97.2 dB.
Ten watts in at 120 Hz requires an excursion of 4.5 mm (or 9 mm peak to peak). This exceeds the transducers Xmax rating and is in part the cause of the distortion rise. This is, however, well within suspension max.
If you want to push the transducer to rated cont power max, then one meter output goes up to 98 db and 3% distortion point will be found at 122 Hz. Not far above the 120 Hz f3 point.
The transducer is also rated at 25 watts peak input. For this input, we produce a one meter sound level of 101.1 dB. Three percent distortion is pushed upward to 162 Hz.
What does this do for us? If this sound level (adjusted for how far away from the loudspeaker you sit) is acceptable, then one possibility for a very high performance system would be to cross at or a little above 120 Hz. Cross to a woofer or sub woofer system. An easy way to put one together would be to use a plate amp. There are affordable plate amps with fourth order low pass filters.
In a sealed enclosure the three-inch will acoustically roll off at 12 dB per octave. At a second order high pass filter and you will have symmetrical slopes. Preserve polarity. At fourth order, you should have acceptable to excellent stereo imaging. But you do not just have to take my word for it. If you decide to try this option you can verify or disprove it yourself.
If we use the plate amp, then it will be easy/simple to MFB the woofer. I suggest the simplest technique. I suggest not trying for more than 6 to 10 dB of feedback.
There is still work to do. We haven't come any closer to being able to rationally suggest a set of transducers at various price points to use in the project, regardless of the low frequency enclosure type.
I ordered the Aura NT1-204-8D tweeters, and then I looked at the frequency response and saw the huge peak out past 20khz. That must be the problem that Dave was referring to.
I ordered parts to do 2nd order linkwitz-riley on both NS3 and NTI, crossing the front NS3 at 5khz (I used 25ohms to calculate, as that is what it looks like on the chart at that frequency) to level out that bump at 7khz. Then crossing the NT1 at 7.5 khz to get close to flat. I will run the rear NS3 fullrange and paint the cone first with acrylic triangles pointing to the center, and then a top coat of modge podge. As the rear driver is mainly used for baffle step, I hope this will dampen it a bit (yeah, I know Mark, but it is an experiment)
Yeah, I realize I should've run this past you guys before I made the order, which is already on the way to Costa Rica and too much of a pain in the #$% to send back.
Is there any way to deal with that huge peak out past 20khz and what will the audible effect be?
Thanks.
I ordered parts to do 2nd order linkwitz-riley on both NS3 and NTI, crossing the front NS3 at 5khz (I used 25ohms to calculate, as that is what it looks like on the chart at that frequency) to level out that bump at 7khz. Then crossing the NT1 at 7.5 khz to get close to flat. I will run the rear NS3 fullrange and paint the cone first with acrylic triangles pointing to the center, and then a top coat of modge podge. As the rear driver is mainly used for baffle step, I hope this will dampen it a bit (yeah, I know Mark, but it is an experiment)
Yeah, I realize I should've run this past you guys before I made the order, which is already on the way to Costa Rica and too much of a pain in the #$% to send back.
Is there any way to deal with that huge peak out past 20khz and what will the audible effect be?
Thanks.
I haven't calculated it, but with this configuration, you lose sensitivity, lose the detail the driver is supposed to reproduce, and image focus as well as stage openess will be reduced somewhat. Some manufacturers put a mask in front of the driver to suppress this, and it causes the same reduction in performance.happy.gringo said:
I suspect that hump is cap resonance, if so, then that is where it needs to be optimally solved for best results.
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