Itwill be interesting to see what test could be constructed that would excludethe effect of the room. All near field? Certainly the distortion would need to be measured as well.
Yes this is a difficult procedure. This assumes the room does not play into the equation. I'm not well versed into creating valid speaker tests so I'm looking to be more a gopher in this exercise.
Near field, since we are mostly concerned with the bass response Measure speaker frequency response - Different techniques
Forgive me all, I'm ignorant to forum etiquette. Should this be in another thread or is it sufficiently on topic to keep in this one?
I don't see a problem. I'm hoping someone will jump in soon and give an answer (or two) to this specific point, it can't be that unusual a question, it could be so obvious that they think we're not serious, I am! No harm in asking, don't ask, don't know
I dont know what the actual "loss" is. What I do know is that this effect I have heard on a number of drivers both planer and piston AND it is the BASS that is effected.
Interesting idea on the misaligned VC thing. Looking at the geometry of the cone/surround/spyder and the trajectory of force however I suspect this would be a small contribution at best.
Agreed, I hear things like DDR (downward dynamic range) and low mechanical loss but trying to consolidate all this into exactly what to look for in drivers and/or design if great sound at low to highish volume is the goal......I'd rather just be told. I don't really have time to investigate in depth.
Things like xxx is what to look for and you implement like this would be fantastic. I'd pay for that in a book or something. Then every case/design should perform as expected and all questions have been answered. I'm currently having trouble because not every case is performing as expected.
I'm at work right now but will do a supremely biased and invalid testing when I get home today.
That sucks but as you say freedom! More time for the fun stuffs!
Attached is picture. The mic is about 12 inches from the Left woofer cone. I'm sitting at the couch. This is not Absolute SPL. I wanted to run some other measurements before using REW to calibrate the Level.
The Loud sweep is as loud as I care to take it.
The Comfortable sweep is normal listening.
The Low sweep is ok.
Below that I don't care for the sound. Everything breaks down.
Something going on with the distortion around 100hz when loud but there are some people walking about (inlaws are here).
Not sure what this test shows only have my other setup will not go as low SPL and still sound ok. I'll try to get some absolute SPL numbers for my listening position.
I actually I don't have an SPL meter so I can't do absolute level. Levels were way below rock concert levels.
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BTW the "loss" of detail / info due to hysteresis effects may not be the type of thing we can see from a FR measurement. I suspect these issues to be worse at lower volumes.
A number of times over the years I have read a review about a speaker were the low level listening was suspect. In every one of them the drivers had cones/ surrounds that were high loss designs. Smooth and sweet BUT something missing and that something got worse at lower volumes.
The manufactures are aware of this. You see a trend towards low loss cones and low hystoresis surrounds. Trickyer to get cone behavior right but when it is there is a clarity similar to low mass film type radiators wich are famous for low level listening quality.
A number of times over the years I have read a review about a speaker were the low level listening was suspect. In every one of them the drivers had cones/ surrounds that were high loss designs. Smooth and sweet BUT something missing and that something got worse at lower volumes.
The manufactures are aware of this. You see a trend towards low loss cones and low hystoresis surrounds. Trickyer to get cone behavior right but when it is there is a clarity similar to low mass film type radiators wich are famous for low level listening quality.
Agreed lowmass. I don't think kind of thing will show on a FR plot. Maybe it would be worth it to make a reasonable sized list of drivers that perform well at low volume and run an analysis on the driver parameters?
I'm sure someone here knows the answer to this. Hopefully they will chime in 🙂.
I'm sure someone here knows the answer to this. Hopefully they will chime in 🙂.
If we are still talking about the change in low frequency response at low volume levels then certainly it would show on the plot 😕
Right I see. I'll redo the test on another woofer I have here and go lower in volume. Will do less smoothing, maybe it will show up more. Its just time right!!
I'm not 100% convinced it is an amplitude thing but if it is I guess that would be good in that we could measure it. It would be bad because we'd have to measure it and would not be able to spec it out.
If karha096 is being adventurous see if they can borrow a GW-1858 in H frame and integrate it with the existing system and see if it comes alive?
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To be clear, my goal would be to be able to pick out a driver with 100% consistent results based on driver spec sheets. Anything other than that is far less than ideal for me as it would mean costing more $$$. I'm sure the manufacturers know all about this so I'd like to leave the research to them. Of course it's in their best interest to sell more drivers............
I too am looking towards my next design and this is one of my primary goals🙂
I too am looking towards my next design and this is one of my primary goals🙂
I was reading last night in Martin Colloms book High perf loudspeakers that something similar was done a while back. The focus was on bass performance and how some speakers seem to have a bass quality thats more "livley and tuneful" and that low level listening was a good test of this quality.
The end of it was this, that after testing a range of commercial systems the common denominator in systems with this bass quality was a high Qms. This basically means suspensions that are low loss and very "springy" in nature.
He went on to say that while high loss surrounds may work well for taming mid range resonances, they seemed to often have a negative effect on bass notes.
Also showed some correlation with the cabinets stuffing material. Certain materials had more hysteresis and that if used too much these can have a similar effect .
Also said something about some manufacture trying a surround that was half high loss, half low loss. Idea was to use the high loss material in direct contact with the cone edge for good mid freq termination wile the larger movements were handled by the low loss section.
I would say in woofers look for high Qms. in midrange/ treeble drivers look for hard stiff diaphragms. All of course well behaved in pass band. These should give the low level detail. From their its largely freq response tailoring.
Just to complicate things a bit with regards to the idea that big drivers are needed for good performance at low volume: In my office, I have a pair of small active monitors (DM10 from British AVI), which have excellent clarity and resolution, escpecially when used as near-field monitors. They are a bit challenged in the size and bass department, of course. Nevertheless, they are stellar at low and moderate volumes, and are probably the first speakers I've had where I don't feel any need to turn up the volume.
Why? I don't know. Here's an alternative idea though: The design goal for these speakers is to remove distortion as much as possible. It may be that for speakers with higher levels of distortion, more volume is needed to mask the distortion, and thus make the speakers sound clear or "alive". When you have less distortion, they may feel clear and without a "veil" even at lower volumes.
Just an hypothesis. I know what my ears tell me though, that these speakers are excellent at low volume, despite being small.
Slight equalization for turning up the bass helps with these as well, though.
Why? I don't know. Here's an alternative idea though: The design goal for these speakers is to remove distortion as much as possible. It may be that for speakers with higher levels of distortion, more volume is needed to mask the distortion, and thus make the speakers sound clear or "alive". When you have less distortion, they may feel clear and without a "veil" even at lower volumes.
Just an hypothesis. I know what my ears tell me though, that these speakers are excellent at low volume, despite being small.
Slight equalization for turning up the bass helps with these as well, though.
Its likley not an amplitude issue. Ther seems to be a certain type of distortion associated with hysteresis that the ear just doesn't like if this property is not used skilfully.
Thanks for the posts, they are very informative. According to voice coil magazine the NE265W-08 has very low distortion as well as high QMS. Perhaps I've been stuffing my sealed enclosures too much?
Sounds like marco is onto something but I have yet to obtain a positive result with the Vifa driver. I will reduce the stuffing and report back. I will also try to track down a copy of that book!
Thanks,
Sounds like marco is onto something but I have yet to obtain a positive result with the Vifa driver. I will reduce the stuffing and report back. I will also try to track down a copy of that book!
Thanks,
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