Hi DHAA,
Let me guess - he used the "fickle finger of fate" to check for an enlarged prostate
.
You can definitely place me in that category.
Ultrasonics is already used in medicine, so indeed, why not infrasonics as well?.
Kind regards,
David
Let me guess - he used the "fickle finger of fate" to check for an enlarged prostate
.You can definitely place me in that category
.Ultrasonics is already used in medicine, so indeed, why not infrasonics as well?
.Kind regards,
David
It seems that most of the studies and personal observations conclude less than 10% THD in the low frequency range is considered acceptable. Considering this thread is about a compact PA sub (and Oliver's health issues, glad to hear the operation has the cancer under control-whip it good!) 120 dB of low frequency is a good level to start with at two meters, that still provides 102 dB at 16 meters (52 feet), or 108 dB for a pair as will typically be used.
Although I now wish I would have paid more for lower distortion drivers to load the PPSL Shoehorn, I rolled the dice and took a chance on some inexpensive drivers that do get loud, and generally won't be driven at levels where distortion would be objectionable, or even noticeable. When I do drive them above 10% distortion, it will probably be reinforcing drums to equal the level of guitar and bass stage amp/speaker combos often driven well over 100% distortion.
In 40 years of live mixing I have never heard anyone comment about distortion they hear in a kick drum, though have heard plenty of comments like "the drums were awesome", although harmonic distortion often may have contributed to the "awesome" sound.
Art
faital pro 1030 hp probably would have been a good fit. giddily awaitin ups to drop my first pair off here in a minute.
notice I shortened the port a bit. stronger motor (and lower vas) seems to maintain the LF output even when this is done, and tuning (displacement minima) is only about 5hz higher
notice I shortened the port a bit. stronger motor (and lower vas) seems to maintain the LF output even when this is done, and tuning (displacement minima) is only about 5hz higher
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Yes, looks like the Faital Pro 15 1030 hp works in a small box too.
Your simulation Fb is around 46 compared to 39 Hz, (almost 1/3 octave higher), using double the 1000 watt AES power rating, using a driver with a lighter weight cone than the Dayton PA385-8. Drop the power to the rated 1000 AES and tuning to 39 Hz and there is not much difference on paper.
Would like to hear what happens in the real world when you hit them with 100 volts.
What box are you planning to use them in?
What is the cost compared to the Dayton PA385-8?
I'm using them in my "mini Othorn" (OTH40c) compact tapped horn, I started a thread o them.
Retail, the price is MUCH different (375) I believe.
lets just say my discount on faital is much better than my discount on BC (or else I'd have got the TBW100).
yeah, 100v would probably make them angry I raised the port tuning because they still hit similar (filtered) spl at 30hz as the daytons, even with the port raised.
my friend is also using them in the "simple slot loaded dual 15s" I started a thread on. Hes almost done with construction and I'm giddy for the results.
Retail, the price is MUCH different (375) I believe.
lets just say my discount on faital is much better than my discount on BC (or else I'd have got the TBW100).
yeah, 100v would probably make them angry
I raised the port tuning because they still hit similar (filtered) spl at 30hz as the daytons, even with the port raised. my friend is also using them in the "simple slot loaded dual 15s" I started a thread on. Hes almost done with construction and I'm giddy for the results.
Excursion is excursion, what is "(filtered) spl" ?yeah, 100v would probably make them angry
my friend is also using them in the "simple slot loaded dual 15s" I started a thread on. Hes almost done with construction and I'm giddy for the results.
I'd like to see some distortion tests on your mini Othhorn and your friend's new speakers to see how they actually perform when you apply the power you are simulating with, and how they perform after heating up.
(filtered) spl is just the output capabilites when applying the necessary hipass to keep things in check at the low end of the passband.
The faital hits xmax at 75 volt in the mini othorn. I'll pm you for details on how to measure distortion (I have smaart 7, but very little skills in using it). I can measure the mini othorn, but the RS15 imitators (straight ported) are in brooklyn, so I doubt I'll be taking any measurments off them any time soon.
It hits xmax at 80 volts in the dual 15 BR enclosure (that's not extremely undersized).
the faital has an extra 2.5mm of excursion, thus the greater output capabilities (excursion limited) even with higher port tuning. If it can take the power thermally is a different matter.
The faital hits xmax at 75 volt in the mini othorn. I'll pm you for details on how to measure distortion (I have smaart 7, but very little skills in using it). I can measure the mini othorn, but the RS15 imitators (straight ported) are in brooklyn, so I doubt I'll be taking any measurments off them any time soon.
It hits xmax at 80 volts in the dual 15 BR enclosure (that's not extremely undersized).
the faital has an extra 2.5mm of excursion, thus the greater output capabilities (excursion limited) even with higher port tuning. If it can take the power thermally is a different matter.
Output capability does not change regardless of the highpass filter, if your HP cuts 24 dB level, and you add 24 dB of boost, (as some dj recently was doing with multiple combined PEQ filters) the driver sees the same voltage.
To test distortion with Smaart, you can simply run sine wave tones (Smaart has a sine wave generator) at the voltage you have decided to test at, then "save" the resultant RTA trace.
The difference in level between the fundamental (test tone) and the harmonics generated (distortion) can then be compared to the graph below to determine the distortion %.
Obviously, systems like LMS or REW that read out distortion directly are far less work, but I still find it interesting to see how the harmonic distortion content looks on an RTA, the relationship between all orders of distortion can be seen at once for each test frequency, examples for various subs including the PPSL ShoeHorn are in the OP.
Volt meters made for USA power will read most accurately around 60 Hz (our AC line frequency), so I set the voltage at 60 Hz and leave the same sine wave generator and amplifier setting for all the tests.
Sine waves cause rapid heating, (twice as fast as the AES test signal) so it is best to have all the frequencies and test labels like this:
35HzOTHc53v
40HzOTHc53v
35HzOTHc75v
40HzOTHc75v
etc.
etc.
typed up before hand to rapidly "cut and paste" in to the name setting. It takes a second (or so) for the screen to "settle down" before you hit save. The 30 and 40 Hz "Keyst77.5V" charts in the OP are an example of not letting the trace "settle down", the noise floor appears higher than it was. With only a few seconds per test, and the time it takes to change to the next frequency, the speaker does not see a very high duty cycle. That said, on a hot day with the sun directly heating the magnet structure I did burn up a Kappa 10 when I started typing some extra notes with the sine wave still on...
I have done my sub distortion testing at 2 meters, mic placed on the ground on axis with the sub in it's normal ground orientation . If your test mic is not rated for low distortion at the levels anticipated, a greater test distance would be needed so the SPL falls within the mic rating.
Art
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When settig hipass in hornresp i generally find the voltage where both the lf excursion peak and the in band excursion peak max out at the same level. I realize adding the hipass is doing nothing bit attenuating the voltage at a specified rate in relation to frequency.
That being said, there is a maximum point in the lf that the drivers can handle (i know you already know all this and have far more experience than myself so dont take this as argumenative). The max output at say, 30hz was similar forthe higher tuned faital box and the lower tuned dayton box, dueto both xmax differences and likely other spec differences (vas being lower on the faital might come in to play)
My mic is crap (well not crap but not noce either). Apex 220 ($45). I doubt its accuracy and its distortion handling qualities but its better than nothing. I'll likely test at 3 meters to be safe, as the mini othorn should be capable of around 127db in passband (or more)
That being said, there is a maximum point in the lf that the drivers can handle (i know you already know all this and have far more experience than myself so dont take this as argumenative). The max output at say, 30hz was similar forthe higher tuned faital box and the lower tuned dayton box, dueto both xmax differences and likely other spec differences (vas being lower on the faital might come in to play)
My mic is crap (well not crap but not noce either). Apex 220 ($45). I doubt its accuracy and its distortion handling qualities but its better than nothing. I'll likely test at 3 meters to be safe, as the mini othorn should be capable of around 127db in passband (or more)
You write "30hz was similar forthe higher tuned faital box and the lower tuned dayton box" as if you have measured them, but you have not even put your Faital drivers in cabinets yet
.Using Hornresp as a guideline for setting the HP is a good idea, but when you actually measure the excursion you may find your drivers similar to the Dayton PA385, the suspension does not allow them to go much past Xmax regardless of the voltage applied. You may also find your cabinet's Fb is not at the predicted frequency.
Your mic is probably fairly typical of cheap measurement mics, you can get good ones, or not so good. The good ones can measure just as flat as mics costing over $1000, but until you compare them to a reference the response is unknown.
Although I used one of my B&K 4004 mics for the last round of tests (I was expecting more SPL at lower frequencies than measured
), the cheap RTA 420 mic (which may use the same capsule as the Apex 220) I usually use would not have been appreciably different other than in the <30 Hz range, where there is only a few dB difference (it reads a bit less). The most variance in the cheap (and not so cheap) mics is generally in the 8 kHz range, though the mic that came with my Terasonde Audio Toolbox (a fairly expensive piece of gear) reads -5 less at 40 Hz and -10 at 20 Hz than a flat response mic, which was why my 2x12" Lab 12 cabinets (a pair of which became the ShoeHorns) are tuned +4 dB at 40 Hz, I thought it was -1 there
.Always a good idea to test the test gear....
Art
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Sorry to drag an old thread up, but I was wondering how these were keeping up after a couple of years. Have they seen much use, or do you just go for the Keystones every time?
I'd like to go for something small, 40Hz, and pretty loud for my Beyma 15"s.
The sim comes out quite well, though port velocity appears to be very high at 89v. The measurements seem to show very minimal compression at 40Hz, though, gaining 2dB from 500w going to 1000w instead of the 3dB a perfect system would show. Perhaps, then, port velocity isn't such a big problem.
It looks like the link to the plans on page 1 has moved, so, Art, if you've still got the plans around, I'd love to see them. If not, I'll probably start from scratch.
Cheers
Chris
I'd like to go for something small, 40Hz, and pretty loud for my Beyma 15"s.
The sim comes out quite well, though port velocity appears to be very high at 89v. The measurements seem to show very minimal compression at 40Hz, though, gaining 2dB from 500w going to 1000w instead of the 3dB a perfect system would show. Perhaps, then, port velocity isn't such a big problem.
It looks like the link to the plans on page 1 has moved, so, Art, if you've still got the plans around, I'd love to see them. If not, I'll probably start from scratch.
Cheers
Chris
Chris,
The 2x15" "Shoehorn" PPSL kick pretty well, but are grossly undersized, so require a lot of LF boost for flat response to 35Hz. They don't have near the LF output potential of the Keystones, if I still had them I'd be using them.
I never documented the conversion from the 2x12" design to the 2x15", so even if the prior link existed it would not help much in reproducing the design. The exterior dimensions are 26.5" x 22.5" x 22.5", half the size of the Keystone, the pictures in post #1 pretty much show what's going on inside.
Cheers,
Art
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