I really can not find any difference between the claims of Mr Wiggins in this patent from 2006:
Patent link 7,039,213
And this patent from Dallas company Babbco Ltd in 1976, figure 9:
Patent link 3,983,337
The last one (from 1976) describes the use of twin coils in combination with a single gap to provide the same effect as what is described as the XBL technology. However, this section is interesting:
Here is Fig 9:
And here are Fig 6-8:
Have I missed something or is this just another prior art patent?
Patent link 7,039,213
And this patent from Dallas company Babbco Ltd in 1976, figure 9:
Patent link 3,983,337
The last one (from 1976) describes the use of twin coils in combination with a single gap to provide the same effect as what is described as the XBL technology. However, this section is interesting:
Here is Fig 9:
And here are Fig 6-8:
Have I missed something or is this just another prior art patent?
Attachments
Last edited:
Wouldn't surprise me, there isn't much WRT speaker design that's been invented in recent decades, just lots of new patents based on expired ones. One company in particular has made a very lucrative business of doing it.
WRT the Babb, I have a couple of small Lorelei 'full-range' drivers with a usable 1.2" [30.48 mm] Xmax and by 'full-range' I mean it, it has an almost completely flat usable 20-20 kHz BW that with at least a 400 W power handling capability at very low distortion based on Alan Babb's in-home testing. For sure, the 250 W I had available at the time I was using them didn't even warm them up except when playing some pipe organ symphonies or action movies at fairly loud levels.
It had a lot of promise and a pity he wasn't able to continue to develop it due to having to sell the company after the Fla. hurricanes ~ destroyed their primary market, though he did do at least one major revision that I didn't get to audition, and the new owners apparently got taken out of play by the last couple of economic down turns shortly after the buyout.
GM
WRT the Babb, I have a couple of small Lorelei 'full-range' drivers with a usable 1.2" [30.48 mm] Xmax and by 'full-range' I mean it, it has an almost completely flat usable 20-20 kHz BW that with at least a 400 W power handling capability at very low distortion based on Alan Babb's in-home testing. For sure, the 250 W I had available at the time I was using them didn't even warm them up except when playing some pipe organ symphonies or action movies at fairly loud levels.
It had a lot of promise and a pity he wasn't able to continue to develop it due to having to sell the company after the Fla. hurricanes ~ destroyed their primary market, though he did do at least one major revision that I didn't get to audition, and the new owners apparently got taken out of play by the last couple of economic down turns shortly after the buyout.
GM
Sounds like a really impressive driver. Please feel free to post more info and pictures in this thread if you feel like.
Hi,
Yes, that's very interesting. As to the Xmax thing, just when you think you had a good idea the ancients seem to always beat you to it. 🙂
Regards,
Yes, that's very interesting. As to the Xmax thing, just when you think you had a good idea the ancients seem to always beat you to it. 🙂
Regards,
I disagree.
First of all, the use of T-shaped pole pieces, meaning pole pieces which do have a larger diameter in the gap(s), was at that point of time a well known method for tuning the end contour of the gap flux profile.
Secondly, the essential function of the technology does not change when the diameter of the pole piece is reduced outside the regions of high flux.
What is also important is that the patent in general describes the function of the 1976 Babb patent and not the function of the grove in the pole piece itself. The descriptions of even thickness pole pieces in the 1976 Babb patent is a part of the sliding teflon bearing and has nothing to do with the gap technology.
The XBL patent completely presents the technology described in Fig. 9 in the 1976 Babb patent as the new "invention", and the 1976 Babb patent is refered to only with a description of the dual coil configuration. If the XBL patent was about the pole piece, then that would have been described as the invention. I think the mentioning of a groove in the pole piece is completely a coincidence, and just proves how obvious that tweak actually is.
First of all, the use of T-shaped pole pieces, meaning pole pieces which do have a larger diameter in the gap(s), was at that point of time a well known method for tuning the end contour of the gap flux profile.
Secondly, the essential function of the technology does not change when the diameter of the pole piece is reduced outside the regions of high flux.
What is also important is that the patent in general describes the function of the 1976 Babb patent and not the function of the grove in the pole piece itself. The descriptions of even thickness pole pieces in the 1976 Babb patent is a part of the sliding teflon bearing and has nothing to do with the gap technology.
The XBL patent completely presents the technology described in Fig. 9 in the 1976 Babb patent as the new "invention", and the 1976 Babb patent is refered to only with a description of the dual coil configuration. If the XBL patent was about the pole piece, then that would have been described as the invention. I think the mentioning of a groove in the pole piece is completely a coincidence, and just proves how obvious that tweak actually is.
that grove looks like outside the gap, at the end of center pole
and looks more like a farraday shield ring
I think the 'XBL groves' are inside the gap
or I may have misunderstood the whole thing
and looks more like a farraday shield ring
I think the 'XBL groves' are inside the gap
or I may have misunderstood the whole thing
Snickers-is,
While I did find it odd that the XBL patent only makes reference to the split-coil embodiment of Babb's patent, I think the XBL patent centers on the pole piece grooves:
I'm willing to be wrong. To really read these patents would be a half day job, that Babb patent is a monster.
While I did find it odd that the XBL patent only makes reference to the split-coil embodiment of Babb's patent, I think the XBL patent centers on the pole piece grooves:
claim 1 on XBL:
claim 2:
The XBL patent also extends the idea to >2 gaps.
I'm willing to be wrong. To really read these patents would be a half day job, that Babb patent is a monster.
Last edited:
Tinitus: are you refering the groove marked 146? If so, it has nothing to do with the discussion.
Thune: I also noticed that they extend the idea to several gaps (two or more). Using 6mm gaps and spaces in combination with 12mm coil gives:
1 gap excursion = 12mm * 0,25. Coil coverage: 0,5. Gap coverage: 1,0. Total coverage: 0,5
2 gaps excursion = 12mm * 0,75. Coil coverage: 0,5. Gap coverage: 0,5. Total coverage: 0,25
3 gaps excursion = 12mm * 1,25. Coil coverage: 0,5. Gap coverage: 0,33. Total coverage: 0,167
It was when experimenting with the difference between 2 and 3 gaps I discovered the patent conflict.
Your quote shows basically the same as the claims, a specified groove in the pole piece that could be a coincidence. What is not a coincidence however, is the specification that the groove in the pole piece and the top plate needs to be opposing.
Yes, the Babb patent is extremely complicated. I believe you would never get approval for all of that in a single patent today.
I am not sure about this either (that is why I started this thread), but it seems to me as if the groove is insignificant to the patent.
Thune: I also noticed that they extend the idea to several gaps (two or more). Using 6mm gaps and spaces in combination with 12mm coil gives:
1 gap excursion = 12mm * 0,25. Coil coverage: 0,5. Gap coverage: 1,0. Total coverage: 0,5
2 gaps excursion = 12mm * 0,75. Coil coverage: 0,5. Gap coverage: 0,5. Total coverage: 0,25
3 gaps excursion = 12mm * 1,25. Coil coverage: 0,5. Gap coverage: 0,33. Total coverage: 0,167
It was when experimenting with the difference between 2 and 3 gaps I discovered the patent conflict.
Your quote shows basically the same as the claims, a specified groove in the pole piece that could be a coincidence. What is not a coincidence however, is the specification that the groove in the pole piece and the top plate needs to be opposing.
Yes, the Babb patent is extremely complicated. I believe you would never get approval for all of that in a single patent today.
I am not sure about this either (that is why I started this thread), but it seems to me as if the groove is insignificant to the patent.
ah, I see the grove #138# now
thanks
well, it does indeed look 'similar' to XBL 😉
did I see XBL design with copper in the groves, somewhere ?
btw, picture shows underhung voice coil
quote
More specifically, the electro-mechanical transducer is comprised of a magnetic structure forming an annular magnetic flux field, and a coil assembly providing a tubular electric current field reciprocally disposed in the flux field. One of the fields, for example the flux field, is continuous and the other field, for example the current field, is divided into subfields, the centers of which are spaced apart the same distance as the distance between the effective edges of the flux field. In other words, the subfields are centered on the effective edges of the continuous field when in the quiescent state. An alternating current field created by applying voltage to the coil results in the conventional interaction between the fields which causes the coil to reciprocate relative to the magnet. As each subfield moves into the flux field, the other subfield moves out of the flux field at the same rate. As a result, a constant coupling force is produced between the two fields for an axial displacement of the coil that is several times that which is possible when both the current field and the flux field are continuous for the same total length.
More specifically, the electro-mechanical transducer is comprised of a magnetic structure forming an annular magnetic flux field, and a coil assembly providing a tubular electric current field reciprocally disposed in the flux field. One of the fields, for example the flux field, is continuous and the other field, for example the current field, is divided into subfields, the centers of which are spaced apart the same distance as the distance between the effective edges of the flux field. In other words, the subfields are centered on the effective edges of the continuous field when in the quiescent state. An alternating current field created by applying voltage to the coil results in the conventional interaction between the fields which causes the coil to reciprocate relative to the magnet. As each subfield moves into the flux field, the other subfield moves out of the flux field at the same rate. As a result, a constant coupling force is produced between the two fields for an axial displacement of the coil that is several times that which is possible when both the current field and the flux field are continuous for the same total length.
describsion says that each end of the voice coil must be positioned at center of each protrusion
its clearly aimed at underhung design
or does i say that the voice coil can move out of the field, and still stay linear
extended underhung maybe ?
its clearly aimed at underhung design
or does i say that the voice coil can move out of the field, and still stay linear
extended underhung maybe ?
Well, first of all, Fig. 9 does not show an underhung design since it has two gaps. An underhung design has a continuous gap with a shorter coil within. It would be just as correct to describe it as two overhung gaps.
The quoted part of the Babb patent describes the use of two coils and one gap. Lets say the gap is 12mm high, and each coil has 6mm winding height. The center of the front coil should then be precisely at the front end of the gap, and the center of the rear coil needs to be precisely at the rear end of the gap. When moving 1mm forwards, the front coil leaves the gap by 1mm while the rear coil enters the gap by 1mm. This means the coils can move 9mm in both directions and the total amount of winding height within the gap will still be 6mm. That means one coil can move completely out of the gap.
Copper in the grooves is just a way to reduce flux modulation within the magnet circuit.
The quoted part of the Babb patent describes the use of two coils and one gap. Lets say the gap is 12mm high, and each coil has 6mm winding height. The center of the front coil should then be precisely at the front end of the gap, and the center of the rear coil needs to be precisely at the rear end of the gap. When moving 1mm forwards, the front coil leaves the gap by 1mm while the rear coil enters the gap by 1mm. This means the coils can move 9mm in both directions and the total amount of winding height within the gap will still be 6mm. That means one coil can move completely out of the gap.
Copper in the grooves is just a way to reduce flux modulation within the magnet circuit.
Yes, it has a lot of potential, though we were at odds over how to improve it. It had way to wide a 'sweet spot' for most HIFI/HT apps, but his main market was wanting even more.
Anyway, I had a lot of good technical info including a paper with CAD? drawings about the VC's design/construction details among other things, but a virus got past Norton some years ago and I lost almost everything except for some info in emails. With the site long gone I retrieved a few things from the internet archives. Regardless, I imagine most of what I have/had could/would get me in trouble if I posted them with its new owners if they , but IIRC correctly the VC data was something Alan was going to present to the AES, so maybe it's available. At this point, about all I remember is how hard it must have been to manufacture to such tight tolerances.
BTW, the Lorelei was pretty far removed in detail from his dad's patent, so considering I could audibly distort the surround at 16 Hz at audible SPL at ~16 ft away without me, Jim Griffin and few others noticing any AMD up to this point or any bottoming at all, it wouldn't surprise me if it wasn't a step up from XBL^2 and then some.
GM
No, I guess you could say Alan and I had a fairly adversarial relationship at best, but for whatever reason he decided my opinions might be of some value to him, so shared some of its design details and eventually offering to send me a pair for evaluation.
Anyway, apparently DC Gold didn't want to pursue the design further, its replacement appears to be a variant of the marine line: DC Gold Audio :: N7C
The Reference 9.5 looks like it might address some of my thoughts for HIFI/HT apps, so will try again to contact them to see if there's any to audition locally: DC Gold Audio :: N9.5R
GM
Anyway, apparently DC Gold didn't want to pursue the design further, its replacement appears to be a variant of the marine line: DC Gold Audio :: N7C
The Reference 9.5 looks like it might address some of my thoughts for HIFI/HT apps, so will try again to contact them to see if there's any to audition locally: DC Gold Audio :: N9.5R
GM
Have no way to know and wasn't able to contact them via their instant call-back, so it may be just a 'ghost' site now. Got to get back to storm clean-up, so try emailing them.
GM
GM
I have never seen any real data on a DC Gold driver ever. That is pretty strange for a very expensive raw driver.
Assuming they continued with Babb's basic design philosophy, then no reason to since their products are optimized for marine apps, i.e. waterproof and must work in small sealed cabs or open back, so it's mostly about driver size, shape, price, power handling and what loading type is required.
After much brow beating by me and to a lesser extent by MJK and one or two others IIRC, Alan did add T/S specs to his site, but I don't have them saved in a format that I can upload here. The Lorelei's specs made a 1 ft^3 sealed cab a near I.B. one [not surprising since it was basically a large ~aperiodically loaded compression driver same as the ground breaking W.E. 555, so hardly original in concept] and the 934's specs calculated a TL so small it required an oversize initial cross sectional area [CSA] to make it big enough to mount it. Still, the guy that built it was pleased with its performance.
GM
After much brow beating by me and to a lesser extent by MJK and one or two others IIRC, Alan did add T/S specs to his site, but I don't have them saved in a format that I can upload here. The Lorelei's specs made a 1 ft^3 sealed cab a near I.B. one [not surprising since it was basically a large ~aperiodically loaded compression driver same as the ground breaking W.E. 555, so hardly original in concept] and the 934's specs calculated a TL so small it required an oversize initial cross sectional area [CSA] to make it big enough to mount it. Still, the guy that built it was pleased with its performance.
GM
- Status
- Not open for further replies.