Clarification
Well, what I meant was I would have guessed "X" in the low range and the new "XA" toptology for mids/highs.
I´m sure the Rushmore is a wonderful speaker, would love to hear it but I supect that will take a long time to happen since I´m in Sweden
"Incidentally, I'm certain no driver available works as a perfect piston."
Since no material is infinitely stiff and always have some time involved in sound propagation, in a "science way of speaking" I guess if one wants to say that there is no perfect pistonic drivers/cones/domes that is valid.
However, for all practical means I think we can conclude that it is possible to put together a speaker that is pistonic in the audio range, and that is enough IMO.
"Relatively speaking, there's an enormous amount of slop in the system with energy being lost in any number of directions."
If we restrict our discussion to driver membranes I can´t see what you mean? "Enormous amount of energy being lost in any number of directions" I can see some amount of energy being lost in a soft flexing speaker cone, however, the higher the sound velocity in the cone(stiffer cone), the less it moves in low frequencys, and therefore less energy storage and loss.
/Peter
Well, what I meant was I would have guessed "X" in the low range and the new "XA" toptology for mids/highs.
I´m sure the Rushmore is a wonderful speaker, would love to hear it but I supect that will take a long time to happen since I´m in Sweden
"Incidentally, I'm certain no driver available works as a perfect piston."
Since no material is infinitely stiff and always have some time involved in sound propagation, in a "science way of speaking" I guess if one wants to say that there is no perfect pistonic drivers/cones/domes that is valid.
However, for all practical means I think we can conclude that it is possible to put together a speaker that is pistonic in the audio range, and that is enough IMO.
"Relatively speaking, there's an enormous amount of slop in the system with energy being lost in any number of directions."
If we restrict our discussion to driver membranes I can´t see what you mean? "Enormous amount of energy being lost in any number of directions" I can see some amount of energy being lost in a soft flexing speaker cone, however, the higher the sound velocity in the cone(stiffer cone), the less it moves in low frequencys, and therefore less energy storage and loss.
/Peter
Re: Bobken
Pan said:"It just shows that you cannot trust what these 'New Boys' on the audio scene have to say, doesn't it?"
Maybe I´m a bit slow here but what´ya mean?
*******his was a bit of 'leg-pulling'. No-one could seriously suggest that Lord Nelson was new to the audio scene, and, in fact one of the first articles I read of his was in 'TAA' and goes back to either the very late 70s or early 80s, and was entitled something like " Cables, science or snake oil?". So you see, I really am a fan, after all!***
I don´t know about that KEF driver you mention, you mean it was
a " bad" pistonic driver?
***No, far from it. In its day, the B139 was very well liked, but, as I said, it did sound a little 'slow' to me, because its 'rigid' diaphragm was rather higher mass compared with some of the later more lightweight cones. It did behave as a very good piston, though, as the diaphragm had a flat front and couldn't flex under normal use because of its thick expanded polystyrene construction, and a thin surface covering of some kind. Bending expanded polystyrene in two planes at once, especially if it is quite thick, is nigh on impossible to do if you try it. I didn't actually try this, but I reckon you could have stood on it without it bending in a 'conical' way, but, of course it will fracture under sufficient load. Also, because of its 'cellular' makeup, it would not be subject to any 'inherent' vibration, since if you tap it to see if it rings, it is about the most resistant substance to excite, that you can find. I have seen some 'stroboscope' photographs of this diaphragm in motion, and its radiating surface was "as flat as a pancake" under all normal usage.
Interestingly, quite recently I saw on a website that one of the enormous Wilson speakers (Grandslam?) was reputed to use this B139 driver, but somehow I doubt the truth of this as it has been out of producton for quite a few years now.***
Also, of course it´s possible to make both a good and bad driver with stiff cone.
*** I am sure you are right!***
"I am no 'X' eXpert ( ), but believing that the 'X' factor was all about reducing distortions, I would have guessed that this would have been at least as important, if not more so, in the upper regions.
It makes me wonder just how important 'X' really is? "
Me too... not being an "X-pert"
Or.... was it maybe X amp to the Volt woofer and Aleph to the mid AND highs?
Please enlighten us Nelson
***Yes, I second that since I reckon I know enough about Nelson to realise that this is no accident.
Going entirely from memory, I seem to recall that the 'X' circuits use these wretched electrolytic caps in their circuits, whereas the Alephs don't, except in the PS, of course. Maybe I am wrong here, I must look back at the circuit differences. Makes me wonder, though, especially if my belief about these caps is correct.
Regards,
Peter:
I follow your line of thinking, but actually I didn't say "Enormous amount of energy" I said "Enormous amount of slop" I was thinking microscopically here and considering the entire system (motor, cone, suspension)
I'm sure you are correct, I'm just one of those systems guys who gets hung-up on the word "perfect" meaning no loss or error of any kind. Whenever someone asks me to design a perfect system, I ask if we can settle for "virtually" perfect!
Mike
I follow your line of thinking, but actually I didn't say "Enormous amount of energy" I said "Enormous amount of slop" I was thinking microscopically here and considering the entire system (motor, cone, suspension)
I'm sure you are correct, I'm just one of those systems guys who gets hung-up on the word "perfect" meaning no loss or error of any kind. Whenever someone asks me to design a perfect system, I ask if we can settle for "virtually" perfect!
Mike
Brian,
Thanks for posting the links to the PHL spec sheets. The PHL home page wants me to upgrade my browser (how rude!!).
From a quick glance at the T/S specs, I would say these are not the drivers used by Pass Labs. Unless of course they had drivers custom made.
The 15 won't go down to 22hz in a sealed box and the 6 can't be used beyond 5Khz for starters. These are designed for ported boxes.
Like I said, I didn't run the numbers.
Have you been able to find any frequency response graphs for any of these drivers?
Thanks,
Russ
Thanks for posting the links to the PHL spec sheets. The PHL home page wants me to upgrade my browser (how rude!!).
From a quick glance at the T/S specs, I would say these are not the drivers used by Pass Labs. Unless of course they had drivers custom made.
The 15 won't go down to 22hz in a sealed box and the 6 can't be used beyond 5Khz for starters. These are designed for ported boxes.
Like I said, I didn't run the numbers.
Have you been able to find any frequency response graphs for any of these drivers?
Thanks,
Russ
As I have explained privately, we referred to "Aleph X"
in-house for years, and still do. The XA designation for
the product was a marketing decision.
As to Kef B139's, perhaps you forget that I came from ESS,
where B139's were practically a religion. Nevertheless, it
became quite modal beyond 1 khZ or so.
in-house for years, and still do. The XA designation for
the product was a marketing decision.
As to Kef B139's, perhaps you forget that I came from ESS,
where B139's were practically a religion. Nevertheless, it
became quite modal beyond 1 khZ or so.
mrothacher said:Peter:
I follow your line of thinking, but actually I didn't say "Enormous amount of energy" I said "Enormous amount of slop" I was thinking microscopically here and considering the entire system (motor, cone, suspension)
Pan----Sorry for being "sloppy" with my words
I'm sure you are correct, I'm just one of those systems guys who gets hung-up on the word "perfect" meaning no loss or error of any kind. Whenever someone asks me to design a perfect system, I ask if we can settle for "virtually" perfect!
Pan----Seems reasonable
Mike
russbryant said:
I couldn't find any response graphs for these speakers. The 1140 6.5" driver seems to have no problems going to 5khz. It also has the same appearance as the drivers used in Rushmore (shown in picture above). The 10" also has a close resemblance (also shown above). As for the 15" driver, it looks like none of the ones on the PHL website are up to the task. It probably was sourced from a different vendor. Who else makes efficient bass drivers?
As for the ribbon tweeter, it does look like a Raven R2 or R3.1 ribbon tweeter, but do they go up to 40khz? (it looks like the bigger r3.1 in terms of size)
I am not trying to reverse engineer these speakers to build my own clone of them, I am just interested in their choice of drivers, as they seem to be very well thought out choices. I hope that more efficient drivers catch on more. Also, with the 6.5" midrange going up to 5k, I would expect the crossover point to be less noticable (and with the xvr active crossover). The typical 2k-3k crossover range seem to be too much in the vocal range of average "monkey casket" speakers.
I won't be able to start any new projects anyway, as I already have a bunch of projects waiting for me, a pair of jordan jx92s mini-monitors, some tangband speakers, and some peerless speakers.
I would like to someday build some efficient 3 way speakers with a raven R2 and the PHL midrange, and a woofer, but this is quite a bit out of my budget for now. I need to finish up college first.
I really like the design of the Rushmore speakers, and hope to hear a pair someday. I wonder when they will ship out to audio places that carry Pass Labs products?
--
Brian
Bobken said:What about the KEF B139 (13" X 9") driver, which was so popular some years ago in some of the high-end UK speakers, especially transmission lines?
If that particular driver didn't act like a true piston, and up to about 350Hz, then I am a monkey's uncle.
The diaphragm was a rigid, flat-fronted, expanded polystyrene slab about 1.5" deep at its thickest part at the centre, and if anyone could encourage that to flex or break-up, then I don't know who!
B139 has a nasty resonance at about 1k and sounds best if used below 200-250 Hz. 100 Hz if you are goinf 1st order.
dave
>The 6.5" driver seems to have no problems going to 5khz
Is that from the PHL document? Or do you have another source?
Look at the 10 and 15 inch drivers, the spec says usable to 1-2Khz but they recommend a crossover in the 300 hz range.
This is pretty typical.
The tweet is crossed at 8khz. Maybe they are using assemetrical xover frequencies. And most likely Kent was not going for a perfectly flat FR anyway so a little dip might be OK.
Anyway the Pass spec sheet says 6 inch not 6.5 so my vote is still not PHL.
>I am not trying to reverse engineer these speakers to build my >own clone of them,
Me neither. But it's kinda fun to guess. Also I'm going to have to build some speakers to go with an 8w tube amp I have one of these days. But I have other speakers that have priority.
>I hope that more efficient drivers catch on more.
Well you can't cheat Newton. To get effeciency you have to give up in other areas.
>I really like the design of the Rushmore speakers, and hope to >hear a pair someday. I wonder when they will ship out to audio >places that carry Pass Labs products?
Me too, but it sort of sounded like they are working on heat issues.
Russ in Tucson
Is that from the PHL document? Or do you have another source?
Look at the 10 and 15 inch drivers, the spec says usable to 1-2Khz but they recommend a crossover in the 300 hz range.
This is pretty typical.
The tweet is crossed at 8khz. Maybe they are using assemetrical xover frequencies. And most likely Kent was not going for a perfectly flat FR anyway so a little dip might be OK.
Anyway the Pass spec sheet says 6 inch not 6.5 so my vote is still not PHL.
>I am not trying to reverse engineer these speakers to build my >own clone of them,
Me neither. But it's kinda fun to guess. Also I'm going to have to build some speakers to go with an 8w tube amp I have one of these days. But I have other speakers that have priority.
>I hope that more efficient drivers catch on more.
Well you can't cheat Newton. To get effeciency you have to give up in other areas.
>I really like the design of the Rushmore speakers, and hope to >hear a pair someday. I wonder when they will ship out to audio >places that carry Pass Labs products?
Me too, but it sort of sounded like they are working on heat issues.
Russ in Tucson
planet10 said:
Yes Dave, you are probably correct here but as I am sure you know they were not designed to be used with first order filters, and using any driver out of its intended 'environment' is bound to give rise to further restrictions.
In any event, this does nothing to counter the comments originally made by Peter, with which I agreed, and I used the B139 as an example to illustrate this. (Having re-read the upper frequency limit mentioned by Peter, I don't agree with that, though, as I tried to show with using the 350Hz comment.)
If any further reinforcement is needed, I can do no better than to quote from "High Performance Loudspeakers" by Martin Colloms, who is one of the highest regarded authorities (in the UK, at least) on such matters.
" The unit (KEF B139) operates as a *pure piston* up to approximately 800Hz, where the first breakup mode occurs."
In reality, as I said before, a X'over at about 350Hz is about as high as I ever wished to take the B139, provided sensible order filters are used, of course, and up to that frequency it satisfies all the parameters I am aware of for it to be described as being "pistonic".
Nelson rather craftily sidestepped both issues I raised, and I don't blame him one bit if he simply doesn't wish to comment directly on them. It is entirely his choice, he is in the business of making a living out of selling this equipment, and I am sure that anyone in the same position would probably wish to keep some things up their sleeves too!.
However, it will have been the designer's ear which gave rise to the deliberate choice of non 'X' amps for most of the drivers, and that is still interesting to me. The fact that Nelson had a preference is significant, even if he was not necessarily certain of precisely what it is from their topologies that gives rise to that preference.
Apparently, in making that choice "Articulation, imaging, warmth, and top-end sweetness" were the factors which influenced this choice, all of which I know to be substantially compromised by the use of electrolytics in or around the signal paths in amplifiers.
Still going from memory (as I get lost in all the threads on 'X', although I have actually read them all), I believe this is one of the most significant differences between the 'X' and non-'X' topologies, together with the differences in (partial?) feed-back, both of which will certainly have an influence (albeit possibly small) on the resultant sound.
In several places, Nelson has himself accepted that 'technical sophistication' in circuits does not *necessarily* result in a better perceived sound, and my question remains the same.
I wonder if the 'X' factor is quite so important to the 'goodness' of sound of these amps, or not? Or is it just possible that this is a similar situation to the 'Stasis' topology, which was not in vogue for very long in spite of its apparent technical superiority?
Anyway, Nelson is to be congratulated for a bit of 'lateral thinking' and coming up with something a little different from the norm, since this is precisely what the audio industry needs, IMHO.
I sincerely hope that he has the commercial success that he undoubtedly deserves with the Rushmore.
Regards,
Now, having had a chance to catch my breath a little, I realize I had been a bit overwhelmed by the Vegas, CES, Cardas binding post sale, and meeting the Pass Labs crew (and winning Jam’s contest). I further realize hadn’t really given my thoughts on the Rushmore. So here they are.
I had a few chances to sit and listen to the Rushmore during my time at the show. I was able to listen to a variety of music and vocals at various levels. When I first arrived, Kent, at the request of a listener was playing some orchestral piece at 116db at the listener (according to an RS SPL meter). The sound was effortless. Kent’s comments somewhere was that there was some headroom to spare. There was no hint of the amps running out steam. From this it was clear that the Rushmore is very capable and highly listenable.
I later got a chance to hear other material, both vinyl and CD, at more reasonable levels. The Rushmore loudspeaker system (Alephs included) were always accurate, engaging, and enjoyable to listen to. Not being a pro critic, you certainly need to take me with a grain of salt, but there are speakers that sound very good, and then there are speakers that not only sound very good, but they just seem to involve you in the music. The Rushmore is the latter. Add to this the granite and vacuum molded cherry wood laminate cabinetry, and the Aleph amplifiers, and you have a loudspeaker system worthy of being a Pass Labs product.
The sound of the Rushmore is no accident. Many kudos are due Nelson, Kent, Desmond, and the Pass Labs crew in developing this jewel of a speaker system.
Thanks again to Nelson and the Pass Labs crew for the hospitality showed me. It was truly my pleasure.
Rodd Yamashita
I had a few chances to sit and listen to the Rushmore during my time at the show. I was able to listen to a variety of music and vocals at various levels. When I first arrived, Kent, at the request of a listener was playing some orchestral piece at 116db at the listener (according to an RS SPL meter). The sound was effortless. Kent’s comments somewhere was that there was some headroom to spare. There was no hint of the amps running out steam. From this it was clear that the Rushmore is very capable and highly listenable.
I later got a chance to hear other material, both vinyl and CD, at more reasonable levels. The Rushmore loudspeaker system (Alephs included) were always accurate, engaging, and enjoyable to listen to. Not being a pro critic, you certainly need to take me with a grain of salt, but there are speakers that sound very good, and then there are speakers that not only sound very good, but they just seem to involve you in the music. The Rushmore is the latter. Add to this the granite and vacuum molded cherry wood laminate cabinetry, and the Aleph amplifiers, and you have a loudspeaker system worthy of being a Pass Labs product.
The sound of the Rushmore is no accident. Many kudos are due Nelson, Kent, Desmond, and the Pass Labs crew in developing this jewel of a speaker system.
Thanks again to Nelson and the Pass Labs crew for the hospitality showed me. It was truly my pleasure.
Rodd Yamashita
Pan said:A shot from the hip;
Philips midrange and 15" is a Volt?
/Peter
Hi,
Should we now call you Colt 45? ("shot from the hip")
I don't know about the Philips mid you mentioned, but I cannot see the 15" bass driver being a Volt, somehow.
The larger Volt units like this usually (always?) have the front-located 'spider' arrangement which you would readily see on the Rushmere pics.
Regards,
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