Are you some clone?
92dB peaks at 2m are not house filling sound.
Why are you defending foolish statements?
Yes, that's round about the numbers for a low end setup - I estimate around 105, 106 for my simple HT setup for a single driver, at a metre. It's "cheating", because there's a separate, powered subwoofer doing most of the work below 180Hz, but above that frequency it would do the job fine.
However, to go for something with decent grunt I would choose a 6" Morel SCM 634, and directly drive that with an amp with, say, 100V rails. This translates to delivering 1000W peaks to the driver, which it can handle, and means near 120dB sound levels at 1m are possible - the sort of SPLs experienced by players within an orchestra.
Hello. I am late to this thread and apologise if someone has made this point. Early in the thread it was an opinion expressed, that speakers have become more fatiguing in recent years. My view is that speakers these days are designed with audio visual capabilities in mind. Needing to reproduce film special effects and speech involve different compromises to reproducing music. I would guess that a lot of the users of this site, like me, predominantly listen to music on their hi fi. Which is why modern speakers are often unpleasing to the ear.
I wonder where you could find a 4" driver with 20mm Xmax. That's about what is required from a 4" to deliver 106 dB @ 180 Hz into acoustic freespace.
Not to mention the several hundred watts of power handling needed.
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Why the emphasis on squeezing ear splitting levels from tiny drivers anyway? Why not just use bigger drivers and be done with it? Surely the extractable SPL vs. distortion is pretty easy to deduce given a driver's size and characteristics. It isn't some conspiracy to cast unwarranted aspersions on great little drivers while allowing those lazy old amplifiers to go scot free.
Why the emphasis on extracting what you perceive to be adequate performance from supermarket TV speakers when for a few dollars you can buy a pair of real hi fi speakers from ebay?
Why the emphasis on extracting what you perceive to be adequate performance from supermarket TV speakers when for a few dollars you can buy a pair of real hi fi speakers from ebay?
I want one!! It seems you're slightly underestimating what you'll get - from http://www.mh-audio.nl/CalcSPL.asp: 4" driver, 20mm Xmax, 180Hz gives me 127dB at 1m - hmmm, not bad at all ...
Because that doesn't solve the problem of then driving them with crap amplifiers!
To repeat, the problem is the amplifier - not the speaker! I've done the exercise too many times not to know what's going on - including getting lends of "monster" amps which fall to bits when asked to produce decent levels, on bookshelf sized speakers. Replace the dud bit of electronics with something having decent grunt, and the same speaker comes to life ...
I was in one of our theaters the other day addressing the issue of typical sound level. Running an action movie at a calibrated level with a sound level meter on "fast" came up with most peaks at 92 and a couple of peaks at 95. I would say the level was loud and probably too loud for some.
Meters will under read the peaks, but 92 is certainly house filling. Again, different people have different expectations or needs. Most of these generalizations are not universal!
David
Well, the calculator is there for you to play with - tell me where it's wrong ...
It's years since I played with a serious speaker driver calculator, trying ideas for 12" Peerless woofers - I can remember being surprised at the time that Xmax hardly figures at all, only the most extreme, lowest bass excursion will push the cone travel into the non-linear area, for a sensible design ...
The calculator or your input data is wrong. I've used Siegfried Linkwitz' Excel spreadsheet. Google it and try for yourself.
A typical 55 cm2 Sd 4" driver in closed box with 20 mm (+/- 10 mm) Xmax can deliver 107 dB at 180 Hz into 4pi. Linkwitz' math is not wrong.
A typical 55 cm2 Sd 4" driver in closed box with 20 mm (+/- 10 mm) Xmax can deliver 107 dB at 180 Hz into 4pi. Linkwitz' math is not wrong.
As usually the case in these situations a combination of factors are involved. The calculators do agree, but we were using different effective areas, different xmax meanings, different enclosure types. I still get 121dB for reflex, closed is 117dB which is what the spl_max1 spreadsheet also gives ... but I'm not sure where you get that 107 dB from ....
Xmax is really only a factor for low frequencies. Excursion drops by a factor of 4 for every Octave you go up. By the upper bass, lower mid frequencies thermal or mechanical power handling becomes the limiting factor. I don't think you will get 20mm pk to pk at 180 Hz. If you start out with a driver of 87dB sensitivity it needs to handle 1000 watts without buckling or frying.
Not likely.
Not likely.
Attachments
Thats a dipole calculator. Is that what you guys were discussing? Obviously the dipole will lose some from cancelation. Is that your 10dB difference?
It calculates both monopole (closed box) SPL as well as dipole SPL for a given path length.
http://www.linkwitzlab.com/spl_max1.xls
http://www.linkwitzlab.com/spl_max1.xls
Who is defending anyone? I simply asked you to answer the same question with some guidelines. Blasting another asking you to give a precise answer is not the way to get the message across.
I did not say PEAKS and did not say HOUSE FILLING SOUND, where you got that from is beyond me, sounds like you know the answer (as do I), but refuse to answer straight up. Choosing to belittle and ridicule is still not answering the question.
Is it possible for you to do without the condescending commentary?
There's something still not adding up - Linzwitz's calculator matches the other if you take Xmax being p-p - which is considered a no-no in the speaker world! The mh-audio.nl calculator very specifically asks for the -,+ val, so no doubts there ...
In looking around I found this interesting post, Acoustic Elegance • View topic - So What's the Deal with Xmax?, which says things get even more complicated ...
In looking around I found this interesting post, Acoustic Elegance • View topic - So What's the Deal with Xmax?, which says things get even more complicated ...
And some of us were out there screaming MORE XMAX since the late '70's. When they did, killed what made a good wide band bass driver garbage. All that excess mass ruined it. Tho I would agree with the findings. What is more important is acoustically matching. We can make a horn with a smaller bass driver and create massive levels due to this matching of acoustical impedance's.
The same is true with transmitting antennas, but instead of weak and foul sounding, the energy is reflected back down the line causing vSWR to rise, burning up the final due to these reflected distortions if high enough (1:1 best, <1:1.5 is ok, >1:2 smoked). Luckily our SS amps are fairly impervious to that problem. The valve guys know this all too well or perhaps not.