Mmmm. You inspired me to perform a dustcapectomy on
a pair, and install a phase plug made of a 1" hex socket
and some Dap caulking compound.
Here are the before-and-after curves:
Thank you Nelson! That was very nice of you. Hmmm, about a db down from 200hz thru 3,000khz with the phase plug installed. I have not added one yet but was going to try... any chance of running another curve without the phase plug? Just a big hole in the middle? If not it's cool... i thought the driver sounded less efficient too and at first thought maybe it wasn't working properly (debris in the gap from the circumcision i performed). Still extends past 10k... pretty cool actually. Either way things look decent. Basically it's a slightly different flavor of the same driver. But the cupped hand sound is 'less' without the dust cap.
Thanks again!
Godzilla
Thanks again!
Godzilla
Hey Zilla,
Sorry for the delay. I don't use them in OB anymore, haven't since shortly after getting the P10 treatment for them. As I mentioned in that post Bud dug up, once they've been fully treated, the B20s front and back waves are so dissimilar that their interaction sounds confused. Sometimes disorienting, actually.
No clue if EnABLing the back would have the same effect as treating there front, or if you'd need to treat the basket or if there's really any solution for that. Not having the wherewithal to even start down that track, I popped them into the large Yamaha bookshelf cases that I use in the living room and was finally treated to the truth of an EnABLed B20, which is to say remarkable clarity, soundstage, imaging and detail. They're paired with B&G Neo3 PDR tweeters on the 2.2uF caps that were already installed in the Yamaha cabinet to bring that last bit of air back in, and the whole thing is still running off my old Pioneer VSX-D411 receiver, so none of this is optimal yet, but even though I know this, the listening experience provided is just so easy, so pleasing, so "out of my way" that I've not yet had more than a passing thought of making any modifications, let alone replacements.
So, the EnABL route is recommended, by me, for boxed implementations of the B20. If you're wanting to go OB with it, installing phase plugs made a tremendous difference over stock, and I'm wondering if the damar part of the P10 treatment would make a noticeable improvement on its own. I used the same Neo3s, sans back cups so they were running dipole as well as the B20, when I had them on OB, and that was a great sounding setup, especially with a nice T-Amp.
Since then, I've replaced the office OB rig with a pair of Dayton RS-100-8s amped and high passed using a Panasonic SA-XR57 receiver (digital amps, but not as good sounding as a T-Amp) and a pair of RS225-8s low passed using a Dayton APA150 (again, not the crystal sound of even a cheap T-Amp, but I needed the crossover). This is a great sounding setup, too, but in a different way, and was a lot more complicated to set up. Its also more compromised, especially in the bass. The RS-225s aren't meant for OB, but they're good quality drivers. Actively crossed and amped, they get great extension well below 30Hz, even on the tiny baffles I'm using, but they run out of steam quickly. I actually have the whole setup high passed down at the bottom through my sound card's drivers, just to keep DVDs from distorting them every time something happens. Just need more driver down low, like a pair or even 4 per side. Now to find the budget for that . . .
Of course, I haven't budgeted anything for the B20 rig in the living room in almost a year, which has allowed me to finally get a nice flat screen in there to compliment them. Finally things look almost as good as they sound, though the video side of things is still more complicated and time consuming, not to mention more expensive
Kensai
Sorry for the delay. I don't use them in OB anymore, haven't since shortly after getting the P10 treatment for them. As I mentioned in that post Bud dug up, once they've been fully treated, the B20s front and back waves are so dissimilar that their interaction sounds confused. Sometimes disorienting, actually.
No clue if EnABLing the back would have the same effect as treating there front, or if you'd need to treat the basket or if there's really any solution for that. Not having the wherewithal to even start down that track, I popped them into the large Yamaha bookshelf cases that I use in the living room and was finally treated to the truth of an EnABLed B20, which is to say remarkable clarity, soundstage, imaging and detail. They're paired with B&G Neo3 PDR tweeters on the 2.2uF caps that were already installed in the Yamaha cabinet to bring that last bit of air back in, and the whole thing is still running off my old Pioneer VSX-D411 receiver, so none of this is optimal yet, but even though I know this, the listening experience provided is just so easy, so pleasing, so "out of my way" that I've not yet had more than a passing thought of making any modifications, let alone replacements.
So, the EnABL route is recommended, by me, for boxed implementations of the B20. If you're wanting to go OB with it, installing phase plugs made a tremendous difference over stock, and I'm wondering if the damar part of the P10 treatment would make a noticeable improvement on its own. I used the same Neo3s, sans back cups so they were running dipole as well as the B20, when I had them on OB, and that was a great sounding setup, especially with a nice T-Amp.
Since then, I've replaced the office OB rig with a pair of Dayton RS-100-8s amped and high passed using a Panasonic SA-XR57 receiver (digital amps, but not as good sounding as a T-Amp) and a pair of RS225-8s low passed using a Dayton APA150 (again, not the crystal sound of even a cheap T-Amp, but I needed the crossover). This is a great sounding setup, too, but in a different way, and was a lot more complicated to set up. Its also more compromised, especially in the bass. The RS-225s aren't meant for OB, but they're good quality drivers. Actively crossed and amped, they get great extension well below 30Hz, even on the tiny baffles I'm using, but they run out of steam quickly. I actually have the whole setup high passed down at the bottom through my sound card's drivers, just to keep DVDs from distorting them every time something happens. Just need more driver down low, like a pair or even 4 per side. Now to find the budget for that . . .
Of course, I haven't budgeted anything for the B20 rig in the living room in almost a year, which has allowed me to finally get a nice flat screen in there to compliment them. Finally things look almost as good as they sound, though the video side of things is still more complicated and time consuming, not to mention more expensive
Kensai
Note that loosely attaching an acoustic 'blanket' over the rear of the driver will nullify any real/perceived EnABL treatment, though of course it will also reduce an OB's typical in-room HF ambiance, so some material and/or thickness experimentation may be required to find an acceptable trade-off.
GM
GM
The driver sounds more open and airy without the dustcap. Funny to me how the fr chart shows barely a difference. Piano notes ring more like a real piano and brushed cymbals are more easily heard and also sound more realistic. Instruments are portrayed with more vibrato. Seems overtones are added when dustcap is removed. I have been enjoying B20 all day without dustcap and occasionally switch to stock driver which always sounds more congested, cupped and darker. Differences clearly favor of the modded driver. I would expect the driver without dustcap to be tipped up in fr somewhere.
Enjoy your new flat screen Kensai.
Godzilla
Enjoy your new flat screen Kensai.
Godzilla
GM,what characteristics would you expect a blanket of damping material to nullify in an EnABL treatment? For sure, if attached to the cone, it will change the entire frequency response character, but EnABL has very little to do with that. It would likely make the low level information more difficult to hear, in the same proportion that applies to the rest of the losses in energy. Is this what you are referring too?
You can treat the backside of any driver, assuming you can get to it with reasonable facility. Doing so adds about 30% more detail and depth of field information, when used in a closed box as in Kensai's application. In open baffle it is a bit weirder. The back wave will become much less disturbed by obstructions and reflected energy in the room will be just part of the music you hear, rather than a separate "problem".
You folks might want to investigate the "Mamboni" process. This being the placement of felt triangles with point towards the voice coil, on the back side of a driver. Would sure kill the Raleigh wave that I nave found on every 8 inch driver I have EnABL'd to date. And it would take care of a bunch of edge reflection problems from the frame to. I am pretty sure you can find this topic in the beginning of the original EnABL thread but it started in an Ohm / Walsh driver thread about the same time. Very effective tool.
In either case, either EnABLing the frame, on the side facing the cone no less, will disappear the frame as a reflection source. This is a royal pain to do and just gluing felt there is easier.
EnABLing your baffle will do almost as much for the quality of the sound as EnABLing the drivers does. For closed or open baffle. For an open baffle you really need to treat both sides of the baffle. With closed boxes you can get very noticeable benefit from treating the inside of the box and the bass port exit, assuming there is one, on the outside of the box, around the port. Alex from Oz has been experimenting with this and can offer some direct application guides. Since any of it can be done with clear tape, it is easy to do and relatively quick. Unlike trying to EnABL the driver back side, useful as that is.
Bud
Hmm, while tightly stretching the blanket over the rear of the driver will alter the response enough to probably nullify some/all of it along with some of its HF output, the point I'm trying to make is that it will damp down the rear output's upper BW response that's apparently causing this 'failure to communicate' in a harmonious way with its direct radiation, at least on Kensai's OBs.
FWIW, when tightly stretched, it's a way to acoustically lower a driver's Qts also.
GM
FWIW, when tightly stretched, it's a way to acoustically lower a driver's Qts also.
GM
I currently have zero experience with open baffle speaker systems. So, I do not know what sort of corruptions an open baffle will apply to a single side EnABL driver. I can say that everything that passes through my hands will perform perfectly as a nude driver, with no baffle support at all.
This, to me, is part of the EnABL process. If it works without baffles, it should work as well or better with some help. In a recent Audio Nirvana 8 inch project, the eventual user was delighted with the driver mounted in his open baffle. He has yet to EnABL the baffle. The driver was back side mounted, with a fairly large diameter radius to the front surface and perhaps this makes a difference. I am sure MJK and John K could help out here.
The nude drivers are set up so that the null zone is parallel to the front face of the basket and right at the edge of the basket. This null is a perturbation in sound quality out to about a radial inch from the baffle and by six inches it has disappeared and moving from back to front just paints the sound of the front of the instruments. On to what you would swear is the sound from the backsides of the players, in reality.
I do have two OB experiments coming up, so I will learn first hand just how much crow I must choke down. Attached is the second of these, utilizing the lovely omni characteristic of the Lowther PM6A.
Bud
This, to me, is part of the EnABL process. If it works without baffles, it should work as well or better with some help. In a recent Audio Nirvana 8 inch project, the eventual user was delighted with the driver mounted in his open baffle. He has yet to EnABL the baffle. The driver was back side mounted, with a fairly large diameter radius to the front surface and perhaps this makes a difference. I am sure MJK and John K could help out here.
The nude drivers are set up so that the null zone is parallel to the front face of the basket and right at the edge of the basket. This null is a perturbation in sound quality out to about a radial inch from the baffle and by six inches it has disappeared and moving from back to front just paints the sound of the front of the instruments. On to what you would swear is the sound from the backsides of the players, in reality.
I do have two OB experiments coming up, so I will learn first hand just how much crow I must choke down. Attached is the second of these, utilizing the lovely omni characteristic of the Lowther PM6A.
Bud
Attachments
Dunno, I just responded to a specific situation. A typical dipole has a rear mids/HF output that's lower than the front's, so all else equal, the front radiation ~completely dominates.
My SWAG though is that the 'softer' on-axis resolution of the EnABLed front radiation is being excessively 'modified' when summed with the relatively more harsh/gross out-of-phase rear output. Taking this assumption to an extreme to clearly hear the problem, listen to a mids/HF compression horn, then remove the driver's rear cover to turn it into a seriously misaligned BLH and listen to it facing the exposed diaphragm. 'Musical it ain't'.
Note that a 'nude' driver has very little front/rear delay until it's beaming pretty good at a reflective surface whereas a baffle delays it enough to isolate it to room and baffle reflections.
GM
My SWAG though is that the 'softer' on-axis resolution of the EnABLed front radiation is being excessively 'modified' when summed with the relatively more harsh/gross out-of-phase rear output. Taking this assumption to an extreme to clearly hear the problem, listen to a mids/HF compression horn, then remove the driver's rear cover to turn it into a seriously misaligned BLH and listen to it facing the exposed diaphragm. 'Musical it ain't'.
Note that a 'nude' driver has very little front/rear delay until it's beaming pretty good at a reflective surface whereas a baffle delays it enough to isolate it to room and baffle reflections.
GM
Mmmm. You inspired me to perform a dustcapectomy on
a pair, and install a phase plug made of a 1" hex socket
and some Dap caulking compound.
Here are the before-and-after curves:
Is that an in-room response curve in your TLs? The knocking down of the peakiness at the very top end is quite the improvement, only a small bandwidth, but a touch more bass and smoother response in the extreme highs.... mo bedda!
A capacitor question
Sorry guys for my ignorance, but at what frequency will a 2.0uF 250V Polypropylene Capacitor cap or split the fr? I am asking because I have used one to add a tweeter to my B20 and now am not sure it is the correct value. (The tweeter's range is from 3500 to 2700HZ)
Thanks for your help
Branko
Sorry guys for my ignorance, but at what frequency will a 2.0uF 250V Polypropylene Capacitor cap or split the fr? I am asking because I have used one to add a tweeter to my B20 and now am not sure it is the correct value. (The tweeter's range is from 3500 to 2700HZ)
Thanks for your help
Branko
http://www.zillaspeak.com/Crossover.asp
A 2uf cap is about 10khz... probably not a bad choice at all... depends on tweeter efficiency. If you like it keep it. Personally i use a cheap piezo and a 1uf cap (and a 22ohm resistor on the piezo) and it sounds great to me.
Godzilla
A 2uf cap is about 10khz... probably not a bad choice at all... depends on tweeter efficiency. If you like it keep it. Personally i use a cheap piezo and a 1uf cap (and a 22ohm resistor on the piezo) and it sounds great to me.
Godzilla
I played around with the B20 a little and here are my subjective results.
http://www.zillaaudio.com/b20-mod.htm
Love this driver!
Godzilla
http://www.zillaaudio.com/b20-mod.htm
Love this driver!
Godzilla
I did some more work on my TLs, having swapped the JBL LE8T that were holding court for the intended pioneer, with a full suite of mods (Enabl, puzzlecoat, basket tweaks, coaxial supertweeter). The TL was built with added bracing and a removable bottom, but more importantly, a very mild front horn load, designed to "help along" the tapering of the dispersion with increasing frequency- most specifically, to very very slightly increase directivity in the 1-4k region, and it seems to have been a success.
Trombones are about as good-sounding as I've heard them, including esoterica. There's still some refinement needed on the upper treble, which can be a little much at times.
These are probably a little more damped in the bass than the version Nelson was using, as mine include a 3.5" x8" x 30" section of "Ultratouch" on the back half of the front chamber.
Thus far we're very happy. Now, to get the wife on-board with including these in the bedroom rig..... might be a challenge....
Trombones are about as good-sounding as I've heard them, including esoterica. There's still some refinement needed on the upper treble, which can be a little much at times.
These are probably a little more damped in the bass than the version Nelson was using, as mine include a 3.5" x8" x 30" section of "Ultratouch" on the back half of the front chamber.
Thus far we're very happy. Now, to get the wife on-board with including these in the bedroom rig..... might be a challenge....
From your webpage: "I have not compared the modified driver to the Fostex I have on hand but will soon to see if the B20s still sound veiled and congested."
Any updated results ? Thanks
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