Good Article by MJK
MJK has published a good article about combining a 90 dB efficient full-ranger with 6~10 dB more efficient woofers with a Qts between 1.0 ~ 1.2. Well worth a read - the rest of the thread is here and worth a read as well.
As most of the readers know, the issue of raising Qts in the bass drivers can be addressed in three ways: decreased magnet size, adding series resistance, or active equalization preceding the power amplifier. Note that smaller magnet size and additional series resistance are exactly equivalent; both decrease BL product while leaving Mms the same, and both decrease efficiency in the piston-band.
What's a little more sobering are the Fostex frequency response curves published in mid-thread by Planet10.
These are about the roughest curves I've ever seen - I consider curves like this "beyond the scope of equalization", and I'm not at all sure EnABL can fix this either. Subjectively, OK, that's different, but I do have a strong predisposition towards drivers that measure flat - I'm the BBC/Quad fan, after all. Other readers don't seem to mind the up-n-downs at all, so a lot of it comes down to personal taste.
MJK has published a good article about combining a 90 dB efficient full-ranger with 6~10 dB more efficient woofers with a Qts between 1.0 ~ 1.2. Well worth a read - the rest of the thread is here and worth a read as well.
As most of the readers know, the issue of raising Qts in the bass drivers can be addressed in three ways: decreased magnet size, adding series resistance, or active equalization preceding the power amplifier. Note that smaller magnet size and additional series resistance are exactly equivalent; both decrease BL product while leaving Mms the same, and both decrease efficiency in the piston-band.
What's a little more sobering are the Fostex frequency response curves published in mid-thread by Planet10.
These are about the roughest curves I've ever seen - I consider curves like this "beyond the scope of equalization", and I'm not at all sure EnABL can fix this either. Subjectively, OK, that's different, but I do have a strong predisposition towards drivers that measure flat - I'm the BBC/Quad fan, after all. Other readers don't seem to mind the up-n-downs at all, so a lot of it comes down to personal taste.
Re: Good Article by MJK
(Begin off-topic rant)
Oh yes, they do
. Still, in all honesty it looks much worse than it sounds (Lowther, anyone ?): The suckout is not equally objectionable as the peaks, and the one centered around 7.5k (FE126E) is the worst offender. Also, Dave's (planet10) treatment tames quite a bit of those peaks (pls refer to the appropriate thread).
(End off-topic rant)
Rgrds,
Florian
P.S. Lynn, we are looking forward for your RMAF impressions and their impact on this project.
(Begin off-topic rant)
Lynn Olson said:
Oh yes, they do
. Still, in all honesty it looks much worse than it sounds (Lowther, anyone ?): The suckout is not equally objectionable as the peaks, and the one centered around 7.5k (FE126E) is the worst offender. Also, Dave's (planet10) treatment tames quite a bit of those peaks (pls refer to the appropriate thread).(End off-topic rant)
Rgrds,
Florian
P.S. Lynn, we are looking forward for your RMAF impressions and their impact on this project.
RMAF and Magnet Sound
I am too. Who woulda thunk that a guitar speaker would sound good? Not me - but after hearing the Bastanis Apollo (with an Alnico magnet) followed by the 12" Alnico Tone Tubby, well, the answer is yes. I still have a strong predisposition to Alnico and Neodymium magnets, though, and have gotten to the point where ceramic now sounds kind of grainy and crude in comparison.
There's something going on here, can't pin it down, but the vivid tone colors, clear, open and natural-sounding midrange, and a sort of shimmering quality are reminiscent of the best direct-heated triode amplifiers. By comparison, ceramic-magnet drivers have more of the "greyer" and more grungy sound of pentodes-with-feedback. That's part of the reason I've crossed ceramic-magnet drivers off the list, actually - even the ones that measure really well still have that coloration lurking in the background.
This is all very impressionistic, but I've heard this characteristic "Alnico" sound with Lowthers, Bastanis, Tone Tubby, and the Dynavector VX-1s moving-coil cartridge. I'm not as familiar with the signature of neodymium, though, but I expect it's not the same as ceramic or Alnico.
I'm aware that shielding the magnet assembly with a copper-clad pole piece reduces the effect of nonlinear VC inductance, but it certainly doesn't reduce it to zero. As a result of working with many different kinds of transformers in the Amity, Raven, Aurora, and Karna amplifiers, I've found that even quite small changes in transformer core material have an immediately obvious effect on the sound. This is confirmed by long conversations with Per Lundhal, Brian Sowter, Dave Slagle, and Bud Purvine, all of whom make superb transformers with a wide range of different core materials.
I'm hearing similar kinds of transformer-core colorations in loudspeaker magnets, so there has to be some kind of VC/magnet coloration that's getting into the sound of the driver, with nonlinear VC inductance being the most obvious culprit. I suspect there are also lots of second and third-order colorations that don't appear in the VC measurements, which are usually set up to look only for gross nonlinearities.
FlorianO said:
I am too. Who woulda thunk that a guitar speaker would sound good? Not me - but after hearing the Bastanis Apollo (with an Alnico magnet) followed by the 12" Alnico Tone Tubby, well, the answer is yes. I still have a strong predisposition to Alnico and Neodymium magnets, though, and have gotten to the point where ceramic now sounds kind of grainy and crude in comparison.
There's something going on here, can't pin it down, but the vivid tone colors, clear, open and natural-sounding midrange, and a sort of shimmering quality are reminiscent of the best direct-heated triode amplifiers. By comparison, ceramic-magnet drivers have more of the "greyer" and more grungy sound of pentodes-with-feedback. That's part of the reason I've crossed ceramic-magnet drivers off the list, actually - even the ones that measure really well still have that coloration lurking in the background.
This is all very impressionistic, but I've heard this characteristic "Alnico" sound with Lowthers, Bastanis, Tone Tubby, and the Dynavector VX-1s moving-coil cartridge. I'm not as familiar with the signature of neodymium, though, but I expect it's not the same as ceramic or Alnico.
I'm aware that shielding the magnet assembly with a copper-clad pole piece reduces the effect of nonlinear VC inductance, but it certainly doesn't reduce it to zero. As a result of working with many different kinds of transformers in the Amity, Raven, Aurora, and Karna amplifiers, I've found that even quite small changes in transformer core material have an immediately obvious effect on the sound. This is confirmed by long conversations with Per Lundhal, Brian Sowter, Dave Slagle, and Bud Purvine, all of whom make superb transformers with a wide range of different core materials.
I'm hearing similar kinds of transformer-core colorations in loudspeaker magnets, so there has to be some kind of VC/magnet coloration that's getting into the sound of the driver, with nonlinear VC inductance being the most obvious culprit. I suspect there are also lots of second and third-order colorations that don't appear in the VC measurements, which are usually set up to look only for gross nonlinearities.
Excellent. I was toying with the idea of using some of his CCS designs and maybe even making some PCBs to make them easier to build. Good to see it back as it was a very informative site.Lynn Olson said:
I'd be keen to hear of any tech updates to the Tabor from Gary or listening impressions from yourself as I have some rough sketched IDT pentode designs. The PP47 I built using Mullard 47's was great and the 1624's are thin on the ground here.
Yes, BudP mentioned the FE127/Fonkens in a phone call last evening - the EnABL apparently lifted the FE127 into a completely different class, and made it work even better in the Fonken cabinet. I'll have to visit Planet10's website and see how the Fonken works - it sounds like an interesting bass alignment.
Edit: Ah, the Fonken uses resistive loading. I've always liked that alignment, midway between closed and vented-box, and much less sensitive to driver variation in Fs and Qts. How unfortunate the AES Journal never reprinted that chapter of Dr. Small's doctoral dissertation. (They did reprint the sealed and vented-box chapters of the dissertation, which became the most famous articles ever done by the Journal.) I also like the way the Fonken keeps any unsupported panel areas smaller than 5 inches - good move, a little trick I did in the Ariel as well.
BudP has a keen ear for subtle differences (all that transformer tuning over the last 30+ years) and had a lot of good things to say about the modified FE127. He's no more a fan of the unmodified Fostexes than I am, so I was quite interested in his before-and-after comments about the driver and the cabinet. (He's the one that treated the FE127's.)
Edit: Ah, the Fonken uses resistive loading. I've always liked that alignment, midway between closed and vented-box, and much less sensitive to driver variation in Fs and Qts. How unfortunate the AES Journal never reprinted that chapter of Dr. Small's doctoral dissertation. (They did reprint the sealed and vented-box chapters of the dissertation, which became the most famous articles ever done by the Journal.) I also like the way the Fonken keeps any unsupported panel areas smaller than 5 inches - good move, a little trick I did in the Ariel as well.
BudP has a keen ear for subtle differences (all that transformer tuning over the last 30+ years) and had a lot of good things to say about the modified FE127. He's no more a fan of the unmodified Fostexes than I am, so I was quite interested in his before-and-after comments about the driver and the cabinet. (He's the one that treated the FE127's.)
Thanks for your reply, Lynn.
I just finished up a new speaker that I'll be debuting at RMAF. It's a controlled-pattern bipole, and I don't know of anyone else who's doing a speaker with quite this same package of design characteristics. One way of looking it is that I'm trying to combine attributes of a good dipole with horn-like dynamics.
You are correct that constant-directivity waveguides significantly complicate the crossover design. I'd forgotten how darn much work that high-pass section was to get right. Ended up with a 25-element crossover (maybe 26, depending on whether my external tilt-control resistor counts as an additional element, as it's just bypassing a particular resistor in the network).
Looking forward to meeting you. So is my wife - I told her about you and your present project.
Duke
I just finished up a new speaker that I'll be debuting at RMAF. It's a controlled-pattern bipole, and I don't know of anyone else who's doing a speaker with quite this same package of design characteristics. One way of looking it is that I'm trying to combine attributes of a good dipole with horn-like dynamics.
You are correct that constant-directivity waveguides significantly complicate the crossover design. I'd forgotten how darn much work that high-pass section was to get right. Ended up with a 25-element crossover (maybe 26, depending on whether my external tilt-control resistor counts as an additional element, as it's just bypassing a particular resistor in the network).
Looking forward to meeting you. So is my wife - I told her about you and your present project.
Duke
Lynn,
Don't forget Mamboni.
If you recall , he transformed a humble Pioneer 10" woofer into a world class wide-bander, which he crossed-over at 8khz in his beautifully simple two-way design.
I think Mamboni would do very well for the Tone Tubby.
You may find that the voice on a Lowther OB to be somewhat two dimensional sounding; well at least the EX3 did to my ears.
Cilla
Don't forget Mamboni.
If you recall , he transformed a humble Pioneer 10" woofer into a world class wide-bander, which he crossed-over at 8khz in his beautifully simple two-way design.
I think Mamboni would do very well for the Tone Tubby.
You may find that the voice on a Lowther OB to be somewhat two dimensional sounding; well at least the EX3 did to my ears.
Cilla
audiokinesis said:
Hi Duke. Looking forward to hearing it. I'll be on the floor just below you, in the Audiomagus room.
From the looks of the speakers on your website and the drivers you're using, they should sound great!
I get to Denver Wednesday morning and may have 24 or more hours with nothing to do (depending on when the rest of the crew show up) so I may stop by your room early.
Hey all.
Just a reminder for your visit to RMAF starting tomorrow.
Remember to be in the Lowther America room Friday night by around 6 PM to hear an A/B comparison of treated and untreated PM6A drivers, put on by Jon Ver Halen himself. This is in suite 1128.
Jon has said he will attempt to have the A45 drivers there on demo also.
Thom Makris is just down the hall in suite 1130 and he will have the just finished A45 drivers in hand and may well have them in the Le Cleach flare Azura horns for you to listen to. Certainly will be another take on EnABL, on lively drivers, being horny and strutting their stuff.
Also our Panomaniac is going to treat a pair of drivers, in Denver, for display in room 1021. So if you can reach him through Audiomagus you might get to speak with him directly about treating full range drivers. He will have treated two sets and that lofts him into expert class.
Enjoy and be sure to listen to and report on as much as you can, about everyone's endeavors, not just one's started with seeds from my pea patch.
Bud
Just a reminder for your visit to RMAF starting tomorrow.
Remember to be in the Lowther America room Friday night by around 6 PM to hear an A/B comparison of treated and untreated PM6A drivers, put on by Jon Ver Halen himself. This is in suite 1128.
Jon has said he will attempt to have the A45 drivers there on demo also.
Thom Makris is just down the hall in suite 1130 and he will have the just finished A45 drivers in hand and may well have them in the Le Cleach flare Azura horns for you to listen to. Certainly will be another take on EnABL, on lively drivers, being horny and strutting their stuff.
Also our Panomaniac is going to treat a pair of drivers, in Denver, for display in room 1021. So if you can reach him through Audiomagus you might get to speak with him directly about treating full range drivers. He will have treated two sets and that lofts him into expert class.
Enjoy and be sure to listen to and report on as much as you can, about everyone's endeavors, not just one's started with seeds from my pea patch.
Bud
I'll be there!
Also expect to meet up with Alexander of RAAL, buy a pair of the new high-efficiency RAAL double-high ribbon tweeters he brought over from Serbia, and spend time chatting with Edward West from the Seattle area - he's using the 18Sound 8NMB420 for a project of his own, and is generously loaning another pair to evaluate over the next month or so. John Atwood arrived early this evening and is staying at my place in Erie, Colorado, about 30 miles north of the RMAF show.
Friday (and Saturday and Sunday) are going to be a lot of fun! Look forward to seeing all of you!
Also expect to meet up with Alexander of RAAL, buy a pair of the new high-efficiency RAAL double-high ribbon tweeters he brought over from Serbia, and spend time chatting with Edward West from the Seattle area - he's using the 18Sound 8NMB420 for a project of his own, and is generously loaning another pair to evaluate over the next month or so. John Atwood arrived early this evening and is staying at my place in Erie, Colorado, about 30 miles north of the RMAF show.
Friday (and Saturday and Sunday) are going to be a lot of fun! Look forward to seeing all of you!
Emerald Physics CS2 at RMAF
How about this rave about the CS2 from Emerald Physics:
http://www.audiocircle.com/circles/index.php?topic=46315.0
Russell
How about this rave about the CS2 from Emerald Physics:
http://www.audiocircle.com/circles/index.php?topic=46315.0
Russell
LTO on RMAF
Favorite Loudspeakers: Feastrex fullrange drivers, AudioKinesis, and RAAL tweeters. First time I've heard any of these, and impressed with all of them. It underlined the point that the sound quality of the driver was more important than the choice of cabinet style or radiation pattern.
Mixed Impression: The Emerald Physics had great bass and midbass, but a lot more sizzle than I liked from the horn/waveguide. The AudioKinesis had a much better HF - and it should have, since the AK compression driver was a $180 driver compared to the $50 CD in the Emerald, and the AK had a very sophisticated and silky-smooth crossover. The AK system of using an additional rear-facing waveguide was quite successful in what I knew was a very difficult room.
My own system: I listened to my own system right after the show, and can say the Denon HT receiver sounds pretty miserable driving the Ariels. In truth it's a good question how true the Ariels are to the original design - the drivers are supposed to be the same models, but they don't sound as good as I remember the originals. One minor project for this fall is getting the Karna amplifiers back up and running again.
Can't Tell: Yes, I was at the EnABL vs non-EnABL listening session. The assessment was complicated by the fact that the system was bi-amped with a 75 Hz active crossover, and the non-EnABL and EnABL PM6A Lowthers had different impedances at 8 and 16 ohms, thus the guesstimate for the bass-level adjustment was off. This led to the subjective impression of more warmth for the non-EnABL, which I knew was a demo artifact.
Actually, EnABL makes no tonal differences at all, as far as I could tell - a Lowther still sounds very much like a Lowther. Time performance for EnABL may have been a little better, the image was definitely more spacious, mostly in the left-to-right direction. The most evident difference was a subjective drop in what sounded like 2nd and 3rd harmonic distortion - this was mostly good, but did have the drawback of revealing things about the system I didn't care for - gritty-sounding Kimber Kable and possibly the Nelson Pass amplifiers. I'm not much of a fan of hyper-expensive garden-hose-sized cables or transistor amps on efficient speakers, so I can't honestly say how much that biassed my impression of the overall sound.
Overall impression of EnABL: Considerably more open and revealing, but may reveal things about your system you don't like - the tide goes down, you see all kinds of critters you never saw before.
Strongest Afterimage: The RAAL tweeters and what they did to the Lowther PM6A's. Wow. The last time I heard treble like that was the Plasmatronics in 1979. I think these tweeters would improve any loudspeaker - yes, I think they're better than the Goto compression-driver supertweeters or the Acapella ion tweeter, and I've heard both.
Favorite Loudspeakers: Feastrex fullrange drivers, AudioKinesis, and RAAL tweeters. First time I've heard any of these, and impressed with all of them. It underlined the point that the sound quality of the driver was more important than the choice of cabinet style or radiation pattern.
Mixed Impression: The Emerald Physics had great bass and midbass, but a lot more sizzle than I liked from the horn/waveguide. The AudioKinesis had a much better HF - and it should have, since the AK compression driver was a $180 driver compared to the $50 CD in the Emerald, and the AK had a very sophisticated and silky-smooth crossover. The AK system of using an additional rear-facing waveguide was quite successful in what I knew was a very difficult room.
My own system: I listened to my own system right after the show, and can say the Denon HT receiver sounds pretty miserable driving the Ariels. In truth it's a good question how true the Ariels are to the original design - the drivers are supposed to be the same models, but they don't sound as good as I remember the originals. One minor project for this fall is getting the Karna amplifiers back up and running again.
Can't Tell: Yes, I was at the EnABL vs non-EnABL listening session. The assessment was complicated by the fact that the system was bi-amped with a 75 Hz active crossover, and the non-EnABL and EnABL PM6A Lowthers had different impedances at 8 and 16 ohms, thus the guesstimate for the bass-level adjustment was off. This led to the subjective impression of more warmth for the non-EnABL, which I knew was a demo artifact.
Actually, EnABL makes no tonal differences at all, as far as I could tell - a Lowther still sounds very much like a Lowther. Time performance for EnABL may have been a little better, the image was definitely more spacious, mostly in the left-to-right direction. The most evident difference was a subjective drop in what sounded like 2nd and 3rd harmonic distortion - this was mostly good, but did have the drawback of revealing things about the system I didn't care for - gritty-sounding Kimber Kable and possibly the Nelson Pass amplifiers. I'm not much of a fan of hyper-expensive garden-hose-sized cables or transistor amps on efficient speakers, so I can't honestly say how much that biassed my impression of the overall sound.
Overall impression of EnABL: Considerably more open and revealing, but may reveal things about your system you don't like - the tide goes down, you see all kinds of critters you never saw before.
Strongest Afterimage: The RAAL tweeters and what they did to the Lowther PM6A's. Wow. The last time I heard treble like that was the Plasmatronics in 1979. I think these tweeters would improve any loudspeaker - yes, I think they're better than the Goto compression-driver supertweeters or the Acapella ion tweeter, and I've heard both.