a few cuts, some foam, some eq and less hz
after a couple days i was beginning to believe it was cutting off at about 80hz,i could hear lower, but not our beloved sub-bass performance, i took it outside, did some tweaks and it sounds to me like ive found a few less hz?
if one of you clever peeps want to analyze it ?? (i might be wrong) ??
yea, i need to tidy up, but the kids are back in an hour so why bother 😀
YouTube - MAH00019
after a couple days i was beginning to believe it was cutting off at about 80hz,i could hear lower, but not our beloved sub-bass performance, i took it outside, did some tweaks and it sounds to me like ive found a few less hz?
if one of you clever peeps want to analyze it ?? (i might be wrong) ??
yea, i need to tidy up, but the kids are back in an hour so why bother 😀
YouTube - MAH00019
OK, it is all matter of balance and physics.
Then, if all things considered, can a TC Sounds LMS-R 12" woofer (xmax = 29.4 mm) be mounted on a horn-loaded cabinet which was used with JBL 2206H (xmax = 7.4 mm)?
What's the pros and cons?
Doug
Then, if all things considered, can a TC Sounds LMS-R 12" woofer (xmax = 29.4 mm) be mounted on a horn-loaded cabinet which was used with JBL 2206H (xmax = 7.4 mm)?
What's the pros and cons?
Doug
We would be analyzing your recording, not your speaker.
Why don't you down load some low sine wave tones and play them through your speaker ?
You will clearly hear what it is or is not doing then.
You will hear plenty of the harmonics of the fundamental tone if you play them at high volume.
Thermal mass may not be an accurate term. What I was referring to is the weight of the voice coil and the magnet structure. Heat seeks cold, the heat goes into the air and the magnet structure.
A heavy voice coil as in a woofer takes a while to heat up, while a light tweeter diaphragm can heat up to the point of burnout quite rapidly.
When the speaker is cold, the magnet structure wicks the heat and radiates it to the air.
If enough average power is put in to the speaker, the magnet structure will eventually heat up to the point that the air conduction from the vent is the primary exit.
Don't understand what you are saying "If a driver gets to its to its point below the system max excursion point the excursion is very low."
Art
It can be mounted if it fits.
Whether it will work well depends on what the horn-loaded cabinet is.
It was not the term by itself but I didn’t understand what your meaning for the word was (Dutch remember😉). Thanks for the explanation.
"If a driver gets to its to its point below the system max excursion point the excursion is very low." I meant the points in the bandpass were less excursion occurs (in TH's for instance) as a result of the loading type. At these points you need to be careful because at these points most energy will be directly transferred into heat.
There are several points where heat develops; Voice-Coil, Top-plate, magnet and inner core. The top-plate is supposed to transfer its heat into the basket (and its cooling fins). Often this heat is spread well in most modern designs. The heat in the coil however is something else. It is able to transfer its heat to other parts but most of it will be assembled in the coil and in the surrounding air space. Therefore excursion is needed to make sure ‘fresh’ air is pumped in and out of the motor system. Also the heat will be transfer better into the top-plate and inner core when the coil is moving (movement means more friction with air so heat can be transfer more easily).
Like I have stated many times, most drivers we need to re-cone for third parties are the result of power compression in some sort of way and NOT the result of over-excursion. Also something that is not very well known, power compression includes different events and is not linear over the bandpass as some measurements like to suggest. In my view there is a relation with excursion just like a compressor/limiter (re)acts on amplitudes in a music signal in your studio setup. Of course if you force any driver below its Fs and Fb you can damage them physically but those drivers we don't see a lot.
Last edited:
Sorry to be confusing,
Don't study pulse jet engines and tapped horns on the same day.
It is generally not a good idea to have a sliding seal at the highest area of pressure.
Wayne,
Comparing the distortion of my Lab 2x12 ported cabinet to the 12Pi, it is apparent that the "good horn loading" of the 12Pi seems to have reduced the distortion by a few percent, not 10 or 15%.
Interestingly, below the horn cutoff, where you say the push pull arrangement has the most benefit, the 12Pi distortion rises much higher than the ported cabinet.
Art Welter
Attachments
I think a BLH would be far easier to tune really as you could just add an extra section that would increase the horn length.
A TH would be far more difficult however, but I wouldn't say it's impossible.
A TH would be far more difficult however, but I wouldn't say it's impossible.
The difference between pro drivers and automotive drivers is a bit muddy
Looked at the LAB 12 and it sure looks like a home or car audio driver--efficiency is low at around 89dB and Fs is low in comparison to "pro sound" drivers.
A buddy of mine will give me a free 12" woofer, and Eclipse car audio driver with aluminum cone, it has about the same Fs, the efficiency was the same at 89dB but Xmax is much higher at 30mm 😱 TC Sounds made them for Eclipse so it is not a Best Buy Geek Squad fart pipe.
Car audio drivers are very interesting, they are designed to handle the worst thing in the audio world--gangsta kids playing "Bass I love you" with clipping amplifiers choking on the voltage drop coming out of the battery. Read somewhere the most manufactured woofers in the world are car audio 12 inch subwoofers--economy of scale.
My fear is once I learn Horn Response, I'll be modelling everything to check it out.
Looked at the LAB 12 and it sure looks like a home or car audio driver--efficiency is low at around 89dB and Fs is low in comparison to "pro sound" drivers.
A buddy of mine will give me a free 12" woofer, and Eclipse car audio driver with aluminum cone, it has about the same Fs, the efficiency was the same at 89dB but Xmax is much higher at 30mm 😱 TC Sounds made them for Eclipse so it is not a Best Buy Geek Squad fart pipe.
Car audio drivers are very interesting, they are designed to handle the worst thing in the audio world--gangsta kids playing "Bass I love you" with clipping amplifiers choking on the voltage drop coming out of the battery. Read somewhere the most manufactured woofers in the world are car audio 12 inch subwoofers--economy of scale.
My fear is once I learn Horn Response, I'll be modelling everything to check it out.
I would agree though I sold a DJ a speaker I never had thermal or mechanical problems with (EV150X), he managed to burn the voice coil AND rip the spider in one gig.
Many folks like to mash their amps into heavy clipping or heavy limiting, or both, which raises the average power a lot.
With dynamic music and enough power, mechanical failure will happen before the burn.
Tuning the mouth shape and size of a TH is not difficult, but it is time consuming.
Playing the test tones through good headphones will give you an idea of how your ears hear those frequencies. If you set the headphone level to the same level as the speaker at an upper frequency (around 160 Hz), the reduction in level the speaker has at low frequencies will be obvious.
Try this test to see how your ears and headphones do:
http://www.phys.unsw.edu.au/jw/hearing.html
Art
Last edited:
Which proves you used the wrong tool for the job, or simply botched the measurements.
I really like the LAB12 in vented cabinets, it's a great system for moderate SPL and power requirements. But through the passband, it can't compare with a horn loaded system in terms of output or distortion.
Not only did you use the wrong tool for the job, but you're also not very good at interpreting the results.
Compare the distortion measurements of a vented cabinet (or horn, for that matter) below cutoff with my 12Pi below cutoff. The vented cabinet distortion is well above 100%, and most horns are too.
Last edited:
This...It is all about the application.
Most bass horns are not designed to go much below 40hz. A driver with a linear motor system and 30 mm xmax not to mention a lower efficiency is indeed wasted in that type of application. However if you are looking for extension to the 20hz range or even lower with output headroom and power handling then you need a different driver. Horns can lower excursion required for a given output level but at the end of the day big high output low bass takes displacement. There is no way around that.
I am one of the few people that I am aware of that has used some of the drivers being mentioned in this thread in tapped horns and has done a full set of measurements on them. Just make sure you put a square peg in a square hole.
I used the tools at hand to test various BR, Horn, and TH cabinets. Many of them did have distortion well above 100% below Fc or Fb at levels a fraction of rated power.
The Lab 12 loaded cabinets had very low distortion, tested in the exact same way.
Please explain in what way you think the results are "botched" and how you are interpreting the results.
Art Welter
I agree with this for the most part too. Again you need to be looking at the application. If you assume that some punk dj will be laying on the system with heavy amp clipping, limiting and heavily compressed "music" that amounts to a sampled bass drum and some looping sine waves for 12 hours straight then yes a lot of subs will get into thermal trouble with a couple of kw worth of amplifier on them. Perhaps the application is a theater setting where the bass content is much lower much more dynamic and more unpredictable but the overall duty cycle is way lower. Perhaps it is a caraudio app? Power ratings of subs are one of the most overblown and exaggerated but also the most hard to quantify properly because exactly what should the test signal be? You have to wonder how guys on the pro boards routinely recommend using a 2 to 6kw rated amplifier on a single cab like a JBL srx728s without melting the coils out all of the time. I have been using amplifiers of 1000-4000w on single drivers for many years without burning any up to the point of failure. If I chose the right signal I could burn up many 1000w rated drivers with half of that power though I am sure. It is a complicated subject. In general I like to apply enough amplifier to bring the drivers to xmax or a little past to avoid clipping and assure maximum dynamic headroom without much regard for power ratings. Works for me. YMMV.
OK, so then what's with your comments that my 12Pi hornsub having 28% THD below cutoff? That is clear evidence that push-pull drive reduces distortion. There's nothing below cutoff to load the drivers, so the only mechanism to keep distortion from going through the roof is push-pull drive.
The LAB12 is a good woofer, especially for its price. I use it in both hornsubs and direct radiating vented subs. I think they're both great, in their intended applications.
But there's no magic, no way for a simple bass-reflex box with any woofer to prevent distortion from going through the roof below the Helmholtz frequency. If you're trying to tell us that your box magically does, then I'm calling BS.
I think I just did that. I think your data is bogus.
I challenge you to have your speakers tested side by side with mine using LMS. It's more suitable for this kind of testing. It's about time to have another Prosound Shootout anyway.
- Status
- Not open for further replies.