ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hello everyone!
Since yesterday I've been listening a bit to my Beovox MS 150, after refoaming both 25 cm "subwoofers". And now I would like to know something more about this "Uniphase" idea. Do I see correctly, are all the drivers actually pointing to a single point (instead of running "parallel" as usual)? But I guess there is something more behind the "Uniphase" word. I would like to understand things a bit better, in order to look for the best position in the room and so on.
Thanks for sharing your knowledge... :)
Marco
Dom
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Yes indeed,there is some info on this,have look in the archives on this site for the particular speakers you have.
It's also worth pointing out that if you have disconnected drive units to refoam them,you should ensure that they are reconnected in the correct phase,ie,the same polarity that they were connected originally.You can check the polarity of each drive unit by applying a small battery across the terminals,and watching the direction of the cone movement.
Nick
Little bit off Beo maybe, but wander how much B&O and Jamo had common? They both had uniphase type speakers at that era. I dont remember that anyone else had.
blah-blah and photographs as needed
I quote Jon:
As far as I understand it to be, Bang and Olufsen decided on using the filler-driver concept as a way to compensate for the phase shift introduced by a crossover.
Because of the resultant phase shift with a crossover, the driver's polarities usually are reversed so that their acoustic output sums flat at the crossover point. This, however, obviously means the speaker system can never achieve a minimum phase response (zero phase shift being the goal).
What B&O did with the 3-way Uniphase speakers is to design a crossover with symmetrical 2nd order low-pass and high-pass acoustic slopes, but with the drivers connected in phase. Then, in order to counteract the resulting cancellation in response, they used a midrange driver to "fill in" the response - that midrange driver's passband being centered in the middle of the high and low frequency driver's crossover point. Above and below it's passband, the midrange driver's acoustic response rolled off at a shallower rate. This meant that the overall frequency response of the speaker summed flat, yet the drivers were all in phase with each other.
As well, B&O "time-aligned" (physically lined up) the acoustic centers of each respective driver. This is why you see some of the drivers a bit more recessed on the baffle than others. So, the Uniphase designs are "transient-perfect" as well, in that they can (mostly) accurately reproduce a square wave. Notice that "time-aligned" designs which are not also either minimum phase (zero phase shift), or linear phase (the entire passband of the speaker phase-shifted by an equal amount), are not transient perfect.
I believe the 2-way Uniphase speakers have the response of the high-pass and low-pass sections overlapped, and then the hump in response is tuned out.
There are WAY more knowledgeable people than I who discuss this at length. You can probably Google things like "transient perfect" and "filler driver" and find alot of useful, in-depth information. Search for a man named "John Kreskovsky" - he's written a few papers about this subject.
The merits of this design are highly debated, with many people saying you'll never hear the difference. I'm the kind of person that doesn't always trust my ear, but I do believe what I can measure to be true. Within certain limitations, I believe in the merits of these designs.
Many people claim that due to the reflections and phase anomolies introduced just by your listening room, a transient perfect design is a moot point, and I can see where they're coming from.
Also, by nature, these designs have poor vertical polar response, illustrated perfectly by the big difference in sound quality you get when you listen standing up versus sitting down. Even if you could somehow get around the room influences, the Uniphase speakers' transient perfect quality (and really, it would be the same with ANY similar design, not just B&O's) would be evident only through a very narrow listening window. Move up or down off axis out of that listening window, and that phase coherency is lost.
These speakers were made back when B&O was more concerned with technical perfection, IMO. It's not an easy thing to do; what they did, that is. It resulted in a more complex and expensive design, but one they considered worth it. Again, many doubt the validity of these designs in the first place, and don't even bother to acheive these design goals. And I've heard many fine speakers that are nowhere near transient perfect in nature. But there are a number of manufacturers that do strive for this, so I guess it just depends on what you choose to believe.
Jacques
Orava:Little bit off Beo maybe, but wander how much B&O and Jamo had common? They both had uniphase type speakers at that era. I dont remember that anyone else had.
DMacri: Orava: Little bit off Beo maybe, but wander how much B&O and Jamo had common? They both had uniphase type speakers at that era. I dont remember that anyone else had. I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts.
Orava: Little bit off Beo maybe, but wander how much B&O and Jamo had common? They both had uniphase type speakers at that era. I dont remember that anyone else had.
I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts.
Not to mention the original Dahlquist DQ-10, phase and time alignment was a forte of this 5 way design. And it did have a fairly small sweet spot, but man, the sound in that sweet spot was amazing. Sounded best if you did the mirror image and cap mods. I used to sell these back in college.
Recently I ran across the crossover schematic for the DQ-10. Very odd, a combination of both parallel and series crossovers. I've never seen the like. If anyone is interested I'll try and find the schematic and post it.
Oddly enough, the crossovers on the CX series of B&O speakers are series xovers as well, not something you see too often.
Jeff
I'm afraid I'm recovering from the BeoVirus.
Thanks for allt he information!
I have very little time to try out things at home in these days, but I'm happy that you confirm that this design requires finding a precise "sweet spot" (also on the vertical axis) for the best listening condition. This was exactly my feeling while experimentig a bit with the MS 150. The crossover still has the original caps for the moment (so it may not be working exactly as it should), but the general feeling while listening was something like: "Uhm... Let's try to sit higher... No, lower... No, closer... No, I'm too close... No, let's move the speakers a bit... Not yet...". Calssical piano music (very coloursful, with big extension and dynamics, things like Messiaen...) is expecially problematic at the moment.
Do you have any personal experience about an expecially well-working listening set-up in a room with such speakers?
Thanks!
DMacri: Orava: I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts. Not to mention the original Dahlquist DQ-10, phase and time alignment was a forte of this 5 way design. And it did have a fairly small sweet spot, but man, the sound in that sweet spot was amazing. Sounded best if you did the mirror image and cap mods. I used to sell these back in college. R
Orava: I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts.
R
Ah, maybe they didn´t have distributor here at that time... or they were in price category I didn´t dare to look.
Orava: DMacri: Orava: I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts. Not to mention the original Dahlquist DQ-10, phase and time alignment was a forte of this 5 way design. And it did have a fairly small sweet spot, but man, the sound in that sweet spot was amazing. Sounded best if you did the mirror image and cap mods. I used to sell these back in college. R Ah, maybe they didn´t have distributor here at that time... or they were in price category I didn´t dare to look.
They were mainly a product of the mid to late 70's. They looked like Quad electrostats but with cloth grills rather than metal, mainly since John Dahlquist loved Quads. A partner in the company was THE Saul Marantz. They were not efficient, really needed a good high current amp, and we're bass shy, which is why they developed a good subwoofer for them, but the imaging and smoothness were addictive. The midrange driver was a dipole, a conventional cone driver free air mounted with a felt pad over the back. Very placement critical, more so than the MS150, as you had the rear back wave to contend with, like all dipoles.
Back then, there were two stereo stores on the same college town street, we sold Dahlquist, ADS, Polk, Harman Kardon, and a bunch of other high end stuff, and the other dealer sold Klipsch and, ta da, B&O! They went out of business ao we moved into their storefront, then we went under, mainly due to mismanagement. The owner would trade equipment out the back door for coke, which doesn't pay the bills.
When I had my MS150s restored, the restorer, Richard Allen loudspeakers commented that they were exceptionally fine units. He at his own expense had tested them and they produced a practically ruler flat frequency response.
I found that they produced a sound when used with the Beomaster 8000 not dissimilar to the Beolab 5 in that the bass was very detailed but one could play the system at very high levels and not notice until someone else came into the room. The treble was the weak area in my view as in common with the rest of the late range Uniphase speakers, they tended to shriek, probably as the Beomaster started to distort. The earlier M100 was smoother in this regard. They were never my favourite speakers mainly because I found the construction poor in comparison to the earlier models. The grilles were a particularly cheap plastic and the stud for holding them on the speakers are prone to breaking. The wood veneer is nothing like the quality of the M100 though the cabinet construction is novel with the carcass having a bitumen filling. The internal finish is however poor compared to the earlier models, a sign of the decline of the cabinet skills.
These days, watch for the disintegrating foam surrounds and the sticking protection circuit which makes the bass speakers sound as if they have blown! Annoyances include the din plug feeding in directly behind the stand - a pain when these speakers weigh 30kg each!!
Peter
Jeff: Orava: DMacri: Orava: I think Thiel, Vandersteen, and DALI and a few others had similar design goals/attempts. Not to mention the original Dahlquist DQ-10, phase and time alignment was a forte of this 5 way design. And it did have a fairly small sweet spot, but man, the sound in that sweet spot was amazing. Sounded best if you did the mirror image and cap mods. I used to sell these back in college. R Ah, maybe they didn´t have distributor here at that time... or they were in price category I didn´t dare to look. They were mainly a product of the mid to late 70's. They looked like Quad electrostats but with cloth grills rather than metal, mainly since John Dahlquist loved Quads. A partner in the company was THE Saul Marantz. They were not efficient, really needed a good high current amp, and we're bass shy, which is why they developed a good subwoofer for them, but the imaging and smoothness were addictive. The midrange driver was a dipole, a conventional cone driver free air mounted with a felt pad over the back. Very placement critical, more so than the MS150, as you had the rear back wave to contend with, like all dipoles. Back then, there were two stereo stores on the same college town street, we sold Dahlquist, ADS, Polk, Harman Kardon, and a bunch of other high end stuff, and the other dealer sold Klipsch and, ta da, B&O! They went out of business ao we moved into their storefront, then we went under, mainly due to mismanagement. The owner would trade equipment out the back door for coke, which doesn't pay the bills.
You mean these?
http://www.ebay.de/itm/Vintage-Highend-Dahlquist-DQ-10-Marantz-Design-Boxen-Made-in-the-USA-1976-/290774629423?pt=DE_Lautsprecher_Martin&hash=item43b384bc2f
Frankly, then look like "home made"
Jeff: They were mainly a product of the mid to late 70's. They looked like Quad electrostats but with cloth grills rather than metal, mainly since John Dahlquist loved Quads. A partner in the company was THE Saul Marantz. They were not efficient, really needed a good high current amp, and we're bass shy, which is why they developed a good subwoofer for them, but the imaging and smoothness were addictive. The midrange driver was a dipole, a conventional cone driver free air mounted with a felt pad over the back. Very placement critical, more so than the MS150, as you had the rear back wave to contend with, like all dipoles. Back then, there were two stereo stores on the same college town street, we sold Dahlquist, ADS, Polk, Harman Kardon, and a bunch of other high end stuff, and the other dealer sold Klipsch and, ta da, B&O! They went out of business ao we moved into their storefront, then we went under, mainly due to mismanagement. The owner would trade equipment out the back door for coke, which doesn't pay the bills.
In about 1987 I listened to a pair of Dahlquist DQ-10s driven by a Phase Linear 400. Probably the best sounding reproduction of music I've heard ever. And this was outside, on a concrete slab patio.
Source material? Original Sony Discman plugged directly into the Phase Linear power amp.
Bought the Phase Linear but did not have the cash for the DQ-10s.
Regretted to this day.
Yup, that's them! All the upper drivers are on individual baffles the size and distance from the listener being determined by the time alignment and freq range covered. Once heard a setup with double DQ10's, stacked, with two subs, one for each side. Very impressive.
Maybe interesting for those taking part in this thread (if you can read French):
https://docs.google.com/file/d/0BwTS40IaQa16ckdKOVEtQ2xSOUNoR2JhOGV4TVFjdw/edit?pli=1
That talks about the technical concept of the Beovox Uniphase 1st series. The graphs with the square wave response at 0, 15 and 30 degrees on the horizontal plane have been expecially useful for me - it is clear that the MS 150 should stay parallel to the back wall in order to achieve a correct frequency response at the listening point. I'm still experimenting with the position on the vertical axis... :)
Excellent read!
Thank you!
DMacri:I know there is a good write up on this somewhere, but the Uniphase design matched the drivers in frequency and time domains. The angles of the baffles provided some time alignment and the crossovers where low order. This also meant the positioning of the speakers was critical so height and angles really matter. Although a pain to set up properly, they will offer excellent imaging and soundstage depth. More realism than typical speakers.
Could this be reason for poor-looking test measurements? If they have standard setup for it, microphone is just in wrong spot for this kind of speaker.
So, I had fun translating the Finnish details... :D (With Google...)
measurementsInvestment kajunta in a room on the floor in their own pedestal, 5 cm from the wall.The calculated efficiency: 0.43%, the corresponding impedance: 8 ohm.Crack Measured maximum voltage: 4.9 VThe acoustic power level of 1 V voltage of 87.5 dBSpeaker was measured without the front grill.Free field measurement, the measuring microphone was the tweeter height.
The upper graph ist the free field frequency response, the second the power response. "Vas." is left and "Oik" is right.
I think I can say that the graphs don't match what I am hearing, since with a slow frequency sweep I should be able those points at -20 dB - and I don't...
mscili: So, I had fun translating the Finnish details... :D (With Google...) measurementsInvestment kajunta in a room on the floor in their own pedestal, 5 cm from the wall.The calculated efficiency: 0.43%, the corresponding impedance: 8 ohm.Crack Measured maximum voltage: 4.9 VThe acoustic power level of 1 V voltage of 87.5 dBSpeaker was measured without the front grill.Free field measurement, the measuring microphone was the tweeter height. The upper graph ist the free field frequency response, the second the power response. "Vas." is left and "Oik" is right. I think I can say that the graphs don't match what I am hearing, since with a slow frequency sweep I should be able those points at -20 dB - and I don't...
Hum, near... I dont quite know myself these terms in english, but...
"Investment kajunta in room" = Placement in echoroom"Pedestal"(?) = Stand"Crack" = distortion (crack, really...)
I guess that if the mic is at tweeter level, it is too high. Tweeter is positioned slightly downwards, isn't it? So optimal listening position is down from tweeter high, if the speaker is on upright level. Anyway, situation in normal listening room might be complety different.Whats more intresting is that if you are 30 deg offline in either side, there is notch at 5kHz. Tells about critical positioning of these speakers, meaning if in right position 20dB notch on 900Hz might be absent?
Orava: I guess that if the mic is at tweeter level, it is too high. Tweeter is positioned slightly downwards, isn't it? So optimal listening position is down from tweeter high, if the speaker is on upright level. Anyway, situation in normal listening room might be complety different.
I guess that if the mic is at tweeter level, it is too high. Tweeter is positioned slightly downwards, isn't it? So optimal listening position is down from tweeter high, if the speaker is on upright level. Anyway, situation in normal listening room might be complety different.
This is difficult to say, since the tweeter is clearly advanced compared to the other drivers, but it is very difficult to tell if it has any direction upwards or downwards. You can also adjust the position of the loudspeakers by moving a specific part of the stand, having them more or less "upwards"... What I notice is that there is clearly a precise listening height were the imaging and the tonal balance get better. The soundstage gets bigger (expecially vertically) and the intrument get a more "real" and precise quality. Go lower, and everything gets a bit confused; go higher, and you'll get a feeling of more clarity, but loosing "reality" and balance.
Whats more intresting is that if you are 30 deg offline in either side, there is notch at 5kHz. Tells about critical positioning of these speakers, meaning if in right position 20dB notch on 900Hz might be absent?
I don't know, but in my listening position (30 degrees, 1,5 m distance) there is definitely no notch at 5 kHz, nor around 1000 Hz. I'm pretty sure I would be able to hear that. The balance and the imaging get much better if you listen off-axix by 30 degrees... I think that's the way these loudspeakers are supposed to be placed...
I was under the impression that when the speakers were properly situated on the stands, the tweeter part of the cabinet was vertical, and the woofer/mids were aligned forward of the tweeter, with the drivers tilted up. That would be in line with the standard approach of time alignment where the lighter, fastest responding drivers are mounted farther from the listeners ears with the heavier driver closer. Especially with low order, minimum phase crossovers.
My old DCM Time Windows mounted the woofer above the tweeter, and at ear level, so the tweeters were farther from the listeners ear, and displayed excellent time domain response. I've never opened them to see what the crossover topology is like.
Just for curiosity. Does anyone have similar testmeasurements from 150's, maybe from other HiFi mags?