This report by Adire Audio is not entirely correct. The problem lies in the erroneous interpretation of the results they obtained. This statement
is actually wrong because the added mass and the cone stiffness make up an oscillating system. The added mass method is perfect at low frequencies , when the cone approximately moves as rigid piston. However, in the mid frequency range the added mass and the cone stiffness form an oscillating system, whose resonance frequency is dependent on the added mass distribution over the membrane surface and on the fixing strength. Thus, the added mass and the cone will not move as a single moving mass at higher frequencies. The added mass method is valid in the frequency range well below a resonance frequency of the oscillating system "cone stiffness-added mass".
Let's take a look at this picture and try to analyze it. Red is SPL of the raw driver, blue is the driver with 28.5 grams mass added, and green is the driver with the inductor in series (no added mass). Does anyone have any ideas about what's wrong with the blue graph ?!
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That blue line??? That makes no sense by just adding mass. Just compare a JBL 2234 vs 2235. The 2235 has a 35g mass ring added everything else is equal. The result is a shift in Fs and an increase in LF extension and a decrease in midrange level.
How did they add the mass???
Rob
How did they add the mass???
Rob
I noticed that sensitivity o the loudspeaker with the added mass is equal in the midrange to the sensitivity of the raw driver, which is not entirely consistent with the classical T-S theory
This is indeed a great thread but this quote is one of the greatest ever
I've got a real Gandalf vibe reading this, "No me, no thread, I am the thread, I have created the circle (fellowship?) of experts who enlighten me and the community, you are a nagging visitor, THOU SHALL NOT PASS
Just look at the freq resp and the rest of the numbers.316g mms
Mms by itself is not relevant.
John Eargle and John Borwick explain this very well in their books.
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Years ago I heard a pair of Totem Mani-2 at a demo with Krell power amps, and later a pair of Totem Signature Mani-2 with Moon power amps, and they managed impressively.
I couldn't have afforded them, nor a power amp stout enough for them, but at the time at least, they are the only stand mounted speaker I've heard that covered everything with correct sounding heft with any genre of music- voice, instruments, whisper quiet or much louder than I wanted.
I couldn't have afforded them, nor a power amp stout enough for them, but at the time at least, they are the only stand mounted speaker I've heard that covered everything with correct sounding heft with any genre of music- voice, instruments, whisper quiet or much louder than I wanted.
Sorry to sound a bit grumpy on this one, but please go read those books.
They can easily be found in digital format
Both describe the effects of all of this very well with a lot of measurements.
That being said, you can NEVER mention just Mms without mentioning the BL as well.
In addition to that, it's very simply the BL(x) and Kms(x) graphs that count as well as the measurements.
There are woofers with a (relatively) high Mms that perform great.
There are also woofers with a (very) low Mms that perform absolutely horrendous.
It's quite a useless discussion without knowing the context, aka the rest and quality of the motor and structure of the woofer itself.
WAY to many variables.
What people do is just mirror and parrot each other, without showing any additional fundamentals of measurements.
Btw, before people start getting all silly again, I am talking from a objective point of view here.
If it makes you happy on a subjective point of view, please go for it!
Super late reply, but I only use digital sources to evaluate setups. Turntable/cartridge setups are all over the place and not meant to be used for critical listening (imo), this is just a bit of fun on the side
Agreed, I sometimes will resort to assumptions just to get the ball rollin since I lack the ability to accumulate enough data to be sure on a theory. My assumptions were based off of the above chart, I did think about BL and realize its a factor. Assuming that a good spread of driver is on that chart above, including those that perform the best in certain aspects displayed, it is the heaviest mms driver that has the lowest distortion at high volume. The lightest cone, has the highest distortion.... It is not lacking in BL vs Mass. It has higher BL ratio than the 150gram mms driver. This same driver has the highest sensitivity ratings and lowest mms... Still very unscientific without seeing the distortion levels at 2.83volts, I know. Is it unfair to think there might be an advantage in distortion at 2.83v for this style of woofer, given the general relationship of efficiency to distortion? I don't know for certain but there is likely some truth there.
I got lower thd measurements from my single 15" vs the dual 18" ppsl in the upper midrange. I thought this complimentary but to draw conclusions without more strict testing isn't good science. I figured if there was some truth to it, it might exposed in the thread through conversation.
Thank you for sharing the books! I will check them out.
- Loudspeaker Handbook by John Eargle
- Loudspeaker and Headphone Handbook by John Borwick.
Any serious designer should know these from first to last page in my opinion.
99.8% of most questions (except DSP related) can be found in there.
There are a couple of other ones that are a good addition to these.
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It totally depends how they optimized the motor as well as the cone.
So it's so hard to draw any direct conclusions.
Obviously, always within boundaries.
If we are gonna compare extremes, things are more obvious of course.
Exactly!
Basically, the only thing you will notice, is that the freq resp just collapses.
Because that is exactly what mass does.
Although that is looking at the picture from a theoretical view.
A lot of very light cones all suffer from severe impedance mismatch, often resulting in all kinds of problems.
Often resulting in non-linear behavior and distortion.
Technically speaking that is not just the Mms.
The thing is that these mismatches show up as frequency response issues. They will not show up as nonlinear distortion -"impedance" is a linear concept. The mass compliance issues of a wave moving up a cone are basically all linear except in extreme circumstances.