It’s interesting that such attempts at imaging cross into industrial design with disastrous consequences. The dilemma (except for the diyer).
It’s interesting that such attempts at imaging cross into industrial design with disastrous consequences. The dilemma (except for the diyer).
Speaking of dipole panel speakers like Magnepan's or Martin Logans, they certainly image WAY differently. On some kinds of instruments or vocals they have rather entertaining amounts of spatial distortion. One benefit is that they seldom sound small.Originally Posted by Ian Mackenzie
They do share one characteristic with large format speakers in that both exhibit what I call low surface loudness where the SPL generated is spread out over large diaphragms. This probably works against pin point imaging if that's your bag.
Hi John,
Thanks for sharing your association with Dunlavy. He actually set up shop over here in South Australia for a while. Alex Encel sold a lot of these massive monoliths through his retail business Encel Stereo in Bridge Road Richmond an inner suburb of Melbourne.
For those interested in the technical side Dunlavy was obsessed with time domain behaviour of his loudspeakers. Any reference to the spatial qualities of a loudspeaker is a heads up the designer has done his homework.
It’s scientific language but worth a read if you’re trying to join the dots …
https://www.sciencedirect.com/topics...e%20left%20ear.
Of course JBL’s LSR range was all over that.
If you then come full circle and do some listening it’s those fragile transients that if blurred cause all the fuss. I say fragile because loudspeakers tend to do a good job of screwing up these vital sounds to the detriment of imaging. But we listen too them anyway
Again if you’re curious this is a playbook of descriptors used by a loudspeaker designer to assess a design subjectively. It’s quite detailed (sorry for the pun) so grab a coffee.
The start
After all this technical tediousness, it is time to finally move on to the section, which I think is the most important of all, because no measurements, graphs, diagrams and pictures can give a complete picture of the sound of the system. Of course, it is possible to draw some conclusions and predict general trends, but no more.
I will try, as much as I can, to formulate my subjective impressions about the sound of the speakers, relying on generally recognized definitions of sound characteristics. After all, auditory impressions are the final product consumed by our brain.
Soundstage (sound picture)
The scale of the sound picture is the first thing that impresses from the first notes - it is simply huge. The entire sound cloud is located far behind the speakers, which simply dissolve into space. The sound is absolutely not tied to the speakers, you instantly forget about them and a truly living musical canvas unfolds before your eyes without boundaries in width and depth.
The height of the sound picture is quite realistic, there is no feeling that you are watching what is happening on the stage through a narrow slit.
Localization and focusing are excellent, the contours of sound images are very precise and clearly visible, no blurring. In large symphony orchestras, all the instruments are in their places, no one climbs forward and does not try to change with anyone, which is extremely important when listening to classical music.
The depth (echeloning) with the second version of the crossover is excellent, perfectly felt separation of instruments in space. Three-dimensionality of the sound canvas and sonic perspective are felt from the first notes. The sound images are well rendered, there is an air between them. With the first version of the crossover, such 3D sensations are less pronounced.
Transparency is very high over the entire frequency range. The impression of crystal clarity and purity of the sound canvas, especially in the first version of the crossover.
The concert hall atmosphere rendering and reverberation are quite good.
The physicality, fullness and relief of sound images are at an average level and better in the second version of the crossover.
Dynamic characteristics
Microdynamics - the dynamic nuances of all subtle and quiet details are excellent. The high resolution and low inertia of the tweeter together with very low mechanical losses in the midwoofer do their job.
Macrodynamics - thanks to the very low distortion of both drivers, the loudspeaker has an explosive character without a hint of overload. A noticeable compression, maybe only at high sound pressure levels. The sound attack worked out just lightning fast with precise temporal contours. No sluggishness and blurry fronts, everything is very lively and realistic in time.
Timbre
The tonal balance is close to neutral, without any tints. Neither dry nor wet, neither warm nor cold.
The overtonal saturation is at a natural level, not overstated toward excessive colorfulness and not understated toward sterility.
The bass for such micro-speakers is simply amazing - deep, dense, dynamic, weighty and solid. Tight, like a tightly stretched rope and beats like a sledgehammer. It's low-fat and well-structured.
The drums are very dynamic. The double bass and cello are as alive, well readable, with many shades (halftones). The bass character strongly depends on the type of enclosure setting which I described before.
The grand piano sounds with excellent attack, energy and well-defined hammer strikes. The bass guitar with a well-read relief.
The mids are very natural, detailed, transparent and dynamic.
High frequencies are entirely due to the nature of the beryllium tweeter. Very realistic presentation, very fast, with an explosive character, no sluggishness and blurring of the sound attack. Not harsh, not annoying, not tiring.
The clanging and ringing of the percussion are similar to the real ones, only the size of the instruments is smaller. You won't hear the lush, colorful timbre that silk tweeters are known for, but the timbre and percussion attack are conveyed very correctly, therefore, metal cymbals sound very clear, transparent and clear, just like real metal cymbals, and not smeared and dirty, like silk tweeters do.
The right side of the piano keyboard sounds with the first version of the crossover, maybe a little brighter than I would have liked, but everything is within the limits of what is allowed, without glazing.
The nylon strings of classical guitars sound quite natural, while the metal strings of acoustic guitars sound sharp and juicy.
The harpsichord, a very complex instrument, sounds like a harpsichord, with excellent sharpness and resolution of all sounds.
Brass winds sounds with real power, just like the metal winds, not the wood ones.
Orchestral violin string groups sound detailed, smooth and exciting, with high resolution.
Auxiliary characteristics
The resolution is very high. The loudspeakers allow you to view the musical material in the smallest detail.
Purity - very low distortion, no any extraneous sounds and distortions at any volume level.
Engagement - above average. You are not just watching the process from the outside, but even a little involved in it.
IIRC In the late 70's John got a grant of some sort from the Australian government for research into speaker design. I believe his facility was located in or near Adelaide and of course this resulted in the Duntech brand being launched. John was always more interested and better at running a speaker laboratory than a manufacturing facility.
Prior to this he had worked for the US government in some capacity designing antennae's for which a number of patents were issued. I don't think he got a dime from them though. He once mentioned to me that his speakers emulated one of his antennae designs.
I remember one night in particular visiting him in Colorado Springs. He took me and my wife and his wife Joan gambling to a town in the mountains just west of Colorado Springs. I was the big winner, $165.00! Then we went back to his house where we drank port wine until the wee hours of the morning. I had a 11 hour drive later that day back to Iowa nursing a terrible hangover. I had never had port before and never will again!
That's how we'd describe it and separate it from simply 'the image' that pretty much any pair of speakers will create between them. Achieving that level of transparency and realism is difficult and of course not everyone's cup of tea. :-)
I skipped one important stage
The recording process.
The attachment is only a simplified graphic that most can relate to.
(If you have OCD just deal with it)
Unless the recording is done with the artist(s) in one place at one time then imho any attempt at true imaging is not organic. It’s what the producer does with mic setup and at the console and with various effects processors. It’s interesting that raw mic recordings can be a bit dry and uninteresting to the general public. But at the venue it can be a revelation.
So is the recording the weak link in the imaging stakes?
Say what think. There’s no right or wrong answer.
I personally leave it to the producer because only they know the meaning that the artist wants to convey in the recording on the day. The song or tune belongs to them after all.
An example of this is here at number 4
https://www.cnbc.com/2011/07/18/Top-...ncy-Jones.html
4. We Are the World
In 1985, Lionel Richie approached Jones with the idea of an all-star concert tour to benefit African famine relief. Jones had another thought. “I said, ‘Why aren’t we doing records instead? A tour can be a nightmare.’ So we decided to do a record,” Jones told CNBC.
Jones managed to get over 40 of the US top artists to gather after a TV presentation at the A&M studios.
The session went till the next morning. The result is a stunning recording that is the subject of a documentary on Netflix. Jones captures the best that each performer can sing at a memorable session.
This was actually a small monitor style loudspeaker system.
https://hificompass.com/en/projects/...ibliss-4p25b#4
The thing is how do you calibrate or measure good from bad? There are very few standards for measurement of a loudspeaker let alone listening to one. So I think separating it out up helps to focus on each aspect of what your hearing.
With the measurements now available (and accessible) to the diyer the opportunity has arrived to tinker, test and learn at home. It needn’t cost a bomb either with some well informed choices.
I have achieved this with the Mermans and anyone who visits So Cal is welcome to come by and hear/experience a soundstage and image that is totally immersive and unbelievable. This is nothing like my Super Big Reds (Altec 604-E2/aux Utah 15", all triamped). One of the AK gents came by after listening to a $100,000+ system and said the Mermans had better soundstage and imaging and he was totally blown away!
I think that time alignment plays a large part so if horns are involved, the signal should be "processed" for time alignment and this is why the older horns don't image well. Newer horns are more shallow and more of a "wave guide" and I think this is where the difference lies.
BTW, in my view "soundstage" is what is happening between/beyond the speakers and can be created artifically in a studio through mixing, or captured from a live performance. And it doesn't need to be a realistic approach. If the engineer wants to spread the drum kit from the left wall of the room to the right wall of the room, that is his perogative and is still "soundstage".
I think we all agree and that is universally accepted as the definition. Where we head all over the map is when we describe a good, or solid, or realistic, or any particular type of sound stage.
Not to take away from your speakers which I am sure are fine speakers, from the photos you have posted in the past, it is my understanding that your room is quite large so the arrival time of the primary and secondary reflections will be delayed longer than in a smaller room. This helps our brains create a better stereophonic illusion. I would bet this is a significant contribution to their exemplary performance.
The time alignment benefit is possible, but I think the wave guide or better directivity control makes the lion share of what is required for "better" imaging within the sound stage.
When we were working on Project May with the H9800 horn and MTM 1500ALs back in 2004/2005 we worked on a passive network and also a digital multi-amped version using the original DEQX 2 by 6 preamp. Those speakers never really worked in the sound stage department. We were working in a very large room with acoustical treatment and the image was alway extremely flat and planar with zero stage depth. Time aligning the speakers affected the frequency response and therefore the sound, but it had zero effect on the imaging/sound stage.
Widget
PS: Hard to believe that was 20 years ago!
I am sure that the room has a large impact on the image with the "reverse" angle ceiling reflecting sound back to the front wall increasing perceived "depth" but also adding it's own "ambience." Room is 26' long x 16' deep, 7.5' - 16' high. The speakers are ~7.5' apart and ~10.5' from the sweet spot.
The Altecs are on the 16' wall and I pull a chair and automan infront of the sofa cushion to listen to them.
I've spent years working on the Mermans and it really wasn't until I got the crossovers just so, got the Heils to where they are, and time aligned all of the drivers, based on RTA readings at the sweet spot, that the imaging got really good. It just sort of happened and now it is "what it is all about." You can hear when the engineer so much as touches a pan pot.
https://cimg0.ibsrv.net/gimg/www.cor...58107c6978.jpg
Hi Mr Widget,
Your insights provide a possibility to explore a further understanding.
I think most of us have experienced the head in a vice situation at some point. The function of a CD horn is to project a uniform off axis output over a defined area.
Given your experience with different rooms how does that impact on the sound stage in terms of moving the listening position?
The Heil's I find can give you quite a bit latitude to experiment with image focus and the ratio of direct to reflected energy. I started a thread a while back about the topic of absorbing the back-wave the effect of image focus and imaging in general.
You can run them as full dipoles and get a very expansive sound field that lacked focus or experiment with absorbing the the back-wave and trying to find suitable balance that would make the sound field smaller but also focus the imaging and make it less diffuse.
It's quite a bit of fun to be able to change a speakers "signature" as easily and as quickly. All you had to do was to add of remove the fiberglass batting from behind the driver and it was like two different systems.
Rob
"I could be arguing in my spare time"
I had previously been removing the back wave and actually started noticing the increase in "pin-point" imaging when I put the rear half-round in the Heil flattening it's response from ~3kHz to above audibility and "steepening" the 2nd order slope on the 2251J. Though the 2251/Heil are crossover over at ~2.5kHz, the rise in response at ~3-4kHz in the 2251 manifests itself either as constructive or destructive when the two drivers combine. Combined, they create a peak through this range when in phase and a dip if out of phase. The peak is much worse than the dip and steep slopes on both drivers mitigate the problems.
BTW, you need to be careful what you put back there. When I had a sheet of the adhesive-backed noise mat back there, it created a reflection that made a really nasty dip at ~5KHz in the Heil's response. This is when I realized that changes made behind the driver have a direct impact on what comes out the front.
Hello Toddalin
I agree about what you put behind them. I purposely stuck to either felt of fiberglass. I was concerned as well about reflections back through the membrane. I was considering a small sub enclosure but decided against it. Fun drivers!
Rob
"I could be arguing in my spare time"
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