In addition to the BSC, ( 2.2 mH, 7.5 Ohms) which as you see balances it out quite a bit, try a parallel notch filter , 100 uH, 5.7uF, 12 Ohms. Not perfect, but close. Helps a bunch. It's lot less like a cheap table radio.
Still I hope to fix the cone problem instead of mask it, but it gives a hint. If you count a small bypass cap on the BSC network, that is 6 parts to get this thing usable. One more clever than I may know how to combine two parallel filters that are in series.
So far:
This is not the best driver in the range
Full range are no where near full, barely wide band mids
You can play with odd cabinet alignments to get some humps to help the bass but excursion is still a big problem.
You can add more passive parts than my typical 2-way systems and it goes from horrible it just not very good at a cost where buying a much better driver would have paid off.
So, I still don't see the attraction. Going to start doping the cone today.
Still I hope to fix the cone problem instead of mask it, but it gives a hint. If you count a small bypass cap on the BSC network, that is 6 parts to get this thing usable. One more clever than I may know how to combine two parallel filters that are in series.
So far:
This is not the best driver in the range
Full range are no where near full, barely wide band mids
You can play with odd cabinet alignments to get some humps to help the bass but excursion is still a big problem.
You can add more passive parts than my typical 2-way systems and it goes from horrible it just not very good at a cost where buying a much better driver would have paid off.
So, I still don't see the attraction. Going to start doping the cone today.
Very few people would be foolish enough to claim a 'full range' driver was technically 'full range' if by that 20Hz - 20KHz is meant. I prefer wideband myself, more or less depending on the unit in question, since, obviously, generalisations cannot be applied on the basis of experience with a single unit.
By full range, I would mean 80 to 12K. I want a mid I can cross over at 5K or so. Not there yet. That is the goal.
Anyway, round one. Dope back of cone lightly. Rope caulk to smooth basket.
Took only about 1 dB off the breakup but knocked the 1 to 2K hump right in line.
Thinking on round two.
Anyway, round one. Dope back of cone lightly. Rope caulk to smooth basket.
Took only about 1 dB off the breakup but knocked the 1 to 2K hump right in line.
Thinking on round two.
Stage two, Doped face of cone, added another coat first quarter inch in the back. Now we are getting somewhere. Pix failed upload.
Good enough, I am doping the second one and stopping this effort.
I used one coat of Scotch Scrappers Glue on the back
Two thin coats of watered down Golden Gel Medium, self leveling gell "Gesso" on the fronts. Painted it on, wiped it off.
Added a thick coat of the gesso about 3/16 inch on front and back right at the surround. Three coats on the dustcap.
I use "No drip tape" a plumbers caulk to smooth the basket and magnet.
I filled the sheet metal form on the rim of the basket with gesso.
If I had a case of them, I am sure I could do better. I have too many other projects. Time to get them over to Doug to put in his new boxes and see how the sound.
Failed wmf upload. "Security token missing" Whatever. Trying a jpg.
I used one coat of Scotch Scrappers Glue on the back
Two thin coats of watered down Golden Gel Medium, self leveling gell "Gesso" on the fronts. Painted it on, wiped it off.
Added a thick coat of the gesso about 3/16 inch on front and back right at the surround. Three coats on the dustcap.
I use "No drip tape" a plumbers caulk to smooth the basket and magnet.
I filled the sheet metal form on the rim of the basket with gesso.
If I had a case of them, I am sure I could do better. I have too many other projects. Time to get them over to Doug to put in his new boxes and see how the sound.
Failed wmf upload. "Security token missing" Whatever. Trying a jpg.
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Was the dip at 125hz there before doping?
You may want the hear the new boxes with the filters, quite exciting really.
Btw, The lager larger coils are $30+ each, so something to consider; may want to go ahead with a $100 driver (if one is out there that is better in that price range).
Working on two new sets - another MDF/Medex, with improvements. And a super Plywood pair ;-) ;-)
You may want the hear the new boxes with the filters, quite exciting really.
Btw, The lager larger coils are $30+ each, so something to consider; may want to go ahead with a $100 driver (if one is out there that is better in that price range).
Working on two new sets - another MDF/Medex, with improvements. And a super Plywood pair ;-) ;-)
Even though the FF125 seems to have some serious breakup issues, and is far from a glowing example of a full range driver IMHO, I think you expect far too much out of a 4" driver, you're just not going to get a "full range" bottom end from a driver of that size.
If your definition of full range is 80 to 12K then my 8" Coral Flat 8II easily exceed that - their bass response in room is solid down to below 40Hz (roughly +/- 3mm linear Xmax capability in a 45 litre bass reflex box tuned to 43Hz) and their on axis treble response reaches 15Khz or so thanks to a well designed whizzer cone and a radiating aluminium dustcap.
Yes I apply full BSC, yes I have applied foam damping strips to the rear of the cone to improve upper midrange breakup, yes I notch out what is left of a couple of cone resonances at 2Khz and 4Khz, and there is some top end response shaping as well.
But the end result is very good and meets the criteria of full range IMO, and at quite decent SPL levels. The main drawback is the treble is quite directional and not as smooth as my ribbon tweeters, but it's still a very enjoyable listening experience.
Attached on axis response with no BSC, no notch filters or other correction, in other words raw response. Near-field measurement up to 230Hz, 1 metre gated measurement spliced in above 230Hz. The peak and dip around 400-700Hz is actually spurious midrange from a front mounted port (I should have blocked the port during the >230Hz gated part of the measurement...) and the notch at about 16-17Khz only occurs dead on axis - as little as 5-10 degrees off axis that notch goes away and the high end extends out to around 17Khz. The bump at 2Khz and the peak at 4Khz I correct with notches. Bear in mind these are 40 year old drivers too...
Don't tar all full range drivers based on one experience with a 4" Fostex driver... 😉
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DB,
Please remember all of my past comments. I am not even being harsh on Fostex. If you look at their charts, you will see the smaller ones are much better behaved. As luck would have it, this is the road apple of the line where everything aligned against it. I can't prove it, but I think the stamped frame is causing some of the issues after the cone breakup. Too many reflections. If I were to pick one again, I would pick the Mark Audio first.
This specific driver is too difficult to use for a wide-band mid ( cross over at 5K or higher). The smaller ones may do that great. As I don't want to build 4 ways, the mid woofer does need to get down to 80 or below. Obviously, more than one of them would be needed for realistic levels. About the only thing I would use the 125 for is a mid-range in a floor standing 8 inch three way where the woofer can't get up to the 2K where a real tweeter starts to be viable. 200 to 2K, it would do that just fine unless the reflections were just too big a problem. Maybe an active crossover LR-4 at 3500 would work in modified version.
Doug,
Due to gating, ignore anything below 500 Hz in the chart. We need to take them out back to get real LF measurements. Speaker up on a ladder and no room modes.
So, I still don't see the attraction. The physics are against it. With 7 billion people, I am sure there are at least 14 billion opinions. This is but one.
How far down did the original Walsh OM-1 get? I guess you could call the Quad full range as it has only one diaphragm. The small maggies had two motors, but only one diaphragm, so maybe they were full range.
Please remember all of my past comments. I am not even being harsh on Fostex. If you look at their charts, you will see the smaller ones are much better behaved. As luck would have it, this is the road apple of the line where everything aligned against it. I can't prove it, but I think the stamped frame is causing some of the issues after the cone breakup. Too many reflections. If I were to pick one again, I would pick the Mark Audio first.
This specific driver is too difficult to use for a wide-band mid ( cross over at 5K or higher). The smaller ones may do that great. As I don't want to build 4 ways, the mid woofer does need to get down to 80 or below. Obviously, more than one of them would be needed for realistic levels. About the only thing I would use the 125 for is a mid-range in a floor standing 8 inch three way where the woofer can't get up to the 2K where a real tweeter starts to be viable. 200 to 2K, it would do that just fine unless the reflections were just too big a problem. Maybe an active crossover LR-4 at 3500 would work in modified version.
Doug,
Due to gating, ignore anything below 500 Hz in the chart. We need to take them out back to get real LF measurements. Speaker up on a ladder and no room modes.
So, I still don't see the attraction. The physics are against it. With 7 billion people, I am sure there are at least 14 billion opinions. This is but one.
How far down did the original Walsh OM-1 get? I guess you could call the Quad full range as it has only one diaphragm. The small maggies had two motors, but only one diaphragm, so maybe they were full range.
My point is if you had a full range system that actually performed well - eg good bass and treble extension, sufficiently smooth midrange, and sufficient dynamics, you wouldn't be saying things like "I still don't see the attraction", the attraction would be apparent.
Of course you're not going to see any attraction with drivers that are as you rightly point out, little more than wide-range midrange drivers, including a severe resonance at a critical frequency. Even with that resonance dealt with they're still just a small, not very efficient, wide band midrange driver.
IMHO, if you're experimenting in the 4" size range and expecting to get a true full range performance that could replace a multi-way speaker, you're only setting yourself up for disappointment. Drivers of that size always just sound like radio or computer speakers to me, its the physics of the situation that limit the performance of a small driver. (Apologies to those who think otherwise about the performance of small FR drivers)
The difference between a conventional driver and a full range driver is the top end response, not the bottom end. The bottom end is always dictated by the cone area, excursion and other T/S parameters, just like any woofer. There is no magic to a full range driver at low frequencies, its just a standard woofer in that regard and has to be sized appropriately to achieve an acceptable bottom end response. Ignoring a sub, the FR driver has to be as big as the largest driver of a comparable multi-way system.
In a 2 way system (perhaps augmented by a sub for the bottom octave or so) what would you consider to be the minimum acceptable size woofer ? Whatever that is, your FR driver must be at least that big if you're not going to be disappointed by its low end response.
Where the magic comes in on a FR driver is the special cone design that allows the high frequency response to be extended sometimes as much as 3 octaves beyond what you would normally see for the same size woofer. A typical 8" woofer might have a useful upper cut-off before breakup and roll-off of 2Khz, a really good 8" full range driver can go as high as 16Khz or so, albeit with quite directional treble.
Full range drivers can't break the laws of physics at the low frequency end, but they can beat the accepted "norm" of high frequency response for a given size driver by a sizeable margin of as much as 2-3 octaves. (Not that difficult in some ways, as the high frequency breakup control of most conventional cone drivers is atrociously bad, and seemingly getting worse as the years go by and more and more high tech cone materials are used...)
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Ain't that the truth. In terms of smooth extended FR (other considerations set aside), one of the finest midbass / midrange units ever built IMO was the Vifa (latterly Scan Speak) P13WH with its mineral filled poly cone. And that was first introduced, what? 20 years back? Longer? They've stopped making it now, although since its performance remains exceptional & it's still highly regarded this has had a few people scratching their heads. Perhaps another manufacturer could buy it from them, but I won't hold my breath on that score. Alas. I mean, compare it to the ~equivalent sized, somewhat newer Seas units:
Madisound Speaker Store
Madisound Speaker Store
Madisound Speaker Store
Madisound Speaker Store
Excuse the links looking all the same -they do in fact lead to different drivers. Decent units all, but I'm not really seeing any improvements here, at least in terms of FR.
Partly the obsession with 'new' materials is marketing. Not entirely, some do have exceptional performance within their piston BW, but the tradeoff is they often need a heck of a lot of work in the XO.
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Scott - 'struth about the P13WH - as you know this is the midbass that Lynn chose for the Ariel & ME2, which was in fact my inspiration for getting into this whole DIY craziness (it only seems like a life-time ago)
Transmission Line Speakers
I do remember price somewhere in the sub $60 range, which seemed a bit rich at the time ( circa 2000)
Simon: masterful dissertation in your post #290
Transmission Line Speakers
I do remember price somewhere in the sub $60 range, which seemed a bit rich at the time ( circa 2000)
Simon: masterful dissertation in your post #290
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Peerless also had the 850488 from the HDS line with its sandwich cone. Now that driver also had a ruler flat response with a very well controlled upper end, its a shame it isn't around any more too. But then again, if you're doing it right, designing a crossover for a driver with a rising response or with a bit of break-up out of band isn't exactly hard. Makes it easier for the casual DIY mind you.
http://www.d-s-t.com.au/data/Peerless/850488.pdf
http://www.d-s-t.com.au/data/Peerless/850488.pdf
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I am going to take your comment out of context a bit in order to repeat what some others have said already because I think it represents a broader view.
In many cases, users of 4" FR drivers are not trying to replace a multi-way speaker without accepting that there will be differences. There are tradeoffs as always, and there are benefits for DIY'ers using 4" drivers over a multi-way as well as disadvantages. If you expect to gain the potential benefits of a single FR driver without losing any of the advantages of a multi-way then disappointment is assured but I believe there are DIY'ers who have more realistic expectations.
All pretty new to me, however I would add that I have found the 4" (125s) very easy to listen to and enjoyable. No complaints about the bass; the box with the flare ports enhance the bass around 53hz (above the control line).
I don't know...could be a parlor trick; but they do sound nice, very warm.
Subwoofer hooked up, don't use it that much.
I don't know...could be a parlor trick; but they do sound nice, very warm.
Subwoofer hooked up, don't use it that much.
And the Ariel remains one of the finest speakers I've ever heard. A well implemented version 4 (my favourite) or above & Scott is a happy man. OK, so it doesn't have the LF extension of many boxes of similar cabinet size, but I'll happily sacrifice that to get the rest. That thing is as close to distilled water as you can get with moving coil drivers. Whether that necessarily makes for the most enjoyable listen or not is another matter entirely...
I thought I remembered that Daline. 🙂
That's inflation for you. 😱
I might have a stab at doing something inspired by the Ariel at some point soon. Not quite the same, but there's still something about it...
Another loss, although I'd probably want to cross it lower than the Vifa.
Right, although in general the less components you need for compensation the better IMO. Keeps the costs down for a start & removes another variable, which is never a bad thing. That said, since I occasionally like to play with completely OTT XOs I'm not in the best position to complain about that. 😉
For my next trick, I am going 180 from the way DB is suggesting. 2 inchers.
Clearly no bass or loudness: Fountek FR88's. I want to make a pair of small, low power computer speakers. Two a side, F3 at about 125. ( they may be the mid-range I have been looking for)
Back to DB's comments. Gee, if it is possible to make the cones special enough to reach the teens, you'd think someone could make a mid-woofer that does not have such horrible breakup and enough response to reach up to where I want to cross over to a tweeter, 5K or so. 60 to 6K would be fantastic. Anyone know of a very good 7 incher that can go that high? Lucky to get 2 out of most, and I am talking the high priced Scandinavian stuff. So far, my favorite mid-bass is the Seas reed paper cone. I have never heard a poly I like, but it could be I have never heard a good poly, as the fillers and shape matter as much as the poly does.
Time to do some acoustic testing of the little Fountek's.
Clearly no bass or loudness: Fountek FR88's. I want to make a pair of small, low power computer speakers. Two a side, F3 at about 125. ( they may be the mid-range I have been looking for)
Back to DB's comments. Gee, if it is possible to make the cones special enough to reach the teens, you'd think someone could make a mid-woofer that does not have such horrible breakup and enough response to reach up to where I want to cross over to a tweeter, 5K or so. 60 to 6K would be fantastic. Anyone know of a very good 7 incher that can go that high? Lucky to get 2 out of most, and I am talking the high priced Scandinavian stuff. So far, my favorite mid-bass is the Seas reed paper cone. I have never heard a poly I like, but it could be I have never heard a good poly, as the fillers and shape matter as much as the poly does.
Time to do some acoustic testing of the little Fountek's.
Here is a thought about the magnet - steel basket connection . Why not just load the space there with several good rubber bands or thick black band if you can find the right size.
Might take the "ring" out of the steel basket.
This thought came from some subwoofers, they have a heavy rubber cup, on the mag, pushing against the steel frame
Might take the "ring" out of the steel basket.
This thought came from some subwoofers, they have a heavy rubber cup, on the mag, pushing against the steel frame
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