Every now and then there are other things that take too much time
, but I'll read and respond.
This largely depends on woofer size and construction. In your case I hardly see any obstacles for a direct radiating (BR) sub solution up to approx. 300 Hz.
Of course, (over)excursion must be taken into account, something that can be overcome by using more cone surface (and a protection measure against 'accidents').
Makes me wonder what these projects look like
The "planned rear subs" are to compensate for room influences I assume? Otherwise this should fullfill anybody's bass needs, except for lovers of 64 feet organ pipes, earthquakes and rocket launches.
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Following the visit to the local audio show and the experiences with 'slightly larger and more sensitive than average' 2-way hi-fi speakers, I was inspired to see if such acclaimed systems could be improved at a considerably lower cost.
I selected 2 woofers, which seem suitable for the job. The concept implies a relatively high sensitivity - still fairly low efficiency though, so that a tube amp. or a quality A/B amp (like the Topping LA90) will suffice in most living rooms.
Both woofers in 80l BR tuned @ 40 Hz @ 40 W Power:
Both are budget woofers, the first from a respected professional audio manufacturer, while the second woofer is made in China and about 50-60% cheaper (and Le is 10x lower).
For comparison, the woofer that's used in a lauded, but very expensive 2-way system. Same cabinet size and tuning, but 65 Watts to achieve the same SPL:
I selected 2 woofers, which seem suitable for the job. The concept implies a relatively high sensitivity - still fairly low efficiency though, so that a tube amp. or a quality A/B amp (like the Topping LA90) will suffice in most living rooms.
Both woofers in 80l BR tuned @ 40 Hz @ 40 W Power:
Both are budget woofers, the first from a respected professional audio manufacturer, while the second woofer is made in China and about 50-60% cheaper (and Le is 10x lower).
For comparison, the woofer that's used in a lauded, but very expensive 2-way system. Same cabinet size and tuning, but 65 Watts to achieve the same SPL:
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Of course this is desirable, but there are some response irregularities in the upper region of the usable range, which are also visible in the measurements of the commercial 2-way speaker.
As previously stated by Dr. Geddes, the midrange should ideally be as clean as possible. My selected woofers need to be crossed lower for optimal directivity matching. However, the response is cleaner, even in the optimal xo region of the latter, least efficient woofer.
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A Jericho J1-94 clone?
View attachment 1111314
I believe a stripped down redesign could potentially make it a very capable hi-fi or studio speaker. A single BMS 4594Nd + 4x 4" or 6" + 4x 15" or 18" should suffice. And while it works, I'd rather get rid of the combiner and instead optimize the throat section and possibly add curvature to the horns.
I'd probably also convert the low section to this; remove 2 and bring the remaining 4 closer together: View attachment 1111323
Although I have serious doubts about severe manipulation of wavefronts for hi-fi applications - bearing in mind the 18Sound XR1496 in the
Ø Audio Icon, this concept appeals to me.
Attachments
Why? Or how do they compensate for room influences? And to what extent?
If you put them inverted and delayed against the back wall, then yes.
multusub approach or DBA, I'll be using rear subs in some type of way to improve FR in the modal region.
If you decide to try both options, the comparison is especially interesting. And SBA is the third
..
There is a lot of conflicting things in that message.
An higher Mms will result in an higher Qt, never a lower.
Based on my professional experience, the efficiency have been gone up, Qt go down but most importantly the vast majority of woofers are a lot more lineair. Demodulation (a lower Le) was never a thing from the past.
Group delay is just plain weird to point out without context.
But heh, what do I know right, after 15 years of working with B&C in high quantities ....
The biggest of all, efficiency is NOT a function of EQ of freq resp.
Efficiency is a function of (input) power. Quite a fundamental mistake.
EQ things changes the overal response, but it does NOT changes the efficiency of a system.
The explanation of the compression driver itself is a little too simplified, therefor missing some important details.
This is VERY well explained in the Loudspeaker Handbook by John Eargle, so I am not gonna explain that myself.
Go have a read there, from page 165 and onward.
But obviously people should know this book by now from the heart I must hope at the bare minimum.
If you don't know this book, (or a similar equivalent) I am not gonna bother debating.
I went back and re-watched the vids based on your comment.
I think you mistook a comment about maximizing sensitivity, and extrapolated it to efficiency. (yes, i know they are related. but not the same....)
At any rate, I think he correct about sensitivity.
If sensitivity is defined as a broadband average measure across a driver's processed response curve, which I believe is the correct way to measure sensitivity, then yes...DSP flattening will maximize honest realizable sensitivity.
I use the method of finding sensitivity by measuring average rms voltage vs average SPL(z), over the same prolonged time interval.
Full band pink passed through all processing in place.
Real world honest measured sensitivity. Sometimes I measure average amperage over the same time interval, and determine true nominal impedance.
Any other method imo, such as the typical manufacturers' eyeballing curves response curves and making a sensitivity judgement call etc, .....is comparative BS.
Fulcrum Acoustics specs includes measured sensitivity with processing in place......
Yes, John Eargle's book is a great resource.
Excellent info on CD's and phase plugs.
Gunness is simply using todays measurement techniques and DSP tools to advance them..
I think that you should think that statement through. In a linear system the efficiency must be independent of input power. Your statement could only be true for a highly nonlinear system. "Quite a fundamental mistake."?
But basically they are the same, just different ways to express he same thing, different units, but one can be derived from the other.