How Black is Black?

Ultra low distortion transducers, how black is black.

There has been increasing chatter about the newer ultra low distortion drivers as of late and rather than possibly hijack one of the several threads currently running I thought it better to start a thread.

I have been debating about writing on this subject for about a year now largely for two reasons, the first being that although there are objective measurements that concur with my observations, this is really in the end, subjective and second that since these drivers are not only very expensive, they are nearly impossible to obtain, the gushing about them here feels like rubbing it in the face of those unable to have them. This of course is not at all the intent.

One last thing to get out of the way, I will not discuss the method of obtainment, who, where, when or dollar amounts. Suffice it to say that they were obtained legally and those who were involved know of my immense gratitude for their generosity and assistance.

OK, to start, I am fortunate to have or have had at least a pair of every JBL 15" driver that I was ever interested in save a nice pair of E145's and the ME150's (arguably two of the numbers I really should have) and have spent real time learning the character of most all of them and I have some pretty strong opinions about most of them. There are several popular 15's that I just don't really care for but that is not what this is about.

I am fortunate to know and or be acquainted with some of the true giants in the field of audio, most of them outside JBL but those that I am acquainted with inside JBL are arguably the guys who know. One of the non JBL guys recently told me something like, "Don't give too much credence to JBL's recent attention to the reduction in distortion, it's really not audible, it's more for marketing." It's not the first time I have disagreed with a professor, I just chalk it up to, he hasn't heard what I haven't heard. How's that for subjective?

To get going, I want to lightly explore a phenomenon that I finally think I understand, what I have heard described as "over powering the room". If you listen sometimes loud in small rooms like I do, (recall that Manfred Schroder defined a space for wide range music of 250,000ft³ or larger) that as the level goes up, the character often changes in a non linear fashion and in the lower registers what can get loud and nasty is the mid bass. What I now believe this is, is harmonic distortion and possibly intermodulation, the roar from below that muddies up the whole bass spectrum.

I have a pair of fairly modified 4350's that are loaded with 1501AL-1's, 1200Fe's, 2440's with TruExtent Be diaphragms and stock 2405's. These are quad amplified with a DBX 4800 processor. They have their limitations like all things but to me and most that hear them, they are flat amazing. I am a measurement geek and have spent some time getting them reasonably flat and they play straight down to 20Hz without boost EQ. For comparison, I have a pristine pair of 4435's and except for slightly better imaging, the 4350's flat kill them, period, no comparison. The 4350's are remarkably full at low level and when you turn them up they sound just the same, only louder. They are very linear and clean.

I had a great experience with them a couple of weeks ago. One of my good friends who is a sound guy, mix guy, does a ton of outdoor sound work and much more came to town for a week and we got spend a couple of days together. He and I are way past sugar coating what we think or seeking validation for projects from each other, we are just interested in making anything we touch better and we frequently bounce ideas around and share knowledge and experience.

We listened to the 1400 Arrays for about an hour and he then asked me if the 4350's were available. We wheeled them to my best room, outside. We started with some material that he had recorded live and mastered himself. Right off the bat, he said, "something's wrong, that organ track is a mono feed and should be dead center".

I recalled that the last time I had them running was in my asymmetrical living room and I was on an experimental flat line kick exploring what would happen if I used every filter at my disposal, I had even used the feedback notch filters (several Hertz wide and up to 80 dB steep) whacking at room resonances just for fun and all those filters were still active. I bypassed them all with a couple of clicks and just like that, snapped them back to life, and center.

By this time he had gathered enough of their sound character to start commenting and said something to the effect of, "wow there is nothing in there that shouldn't be in there, listen to the bass guitar, perfectly clean, great tone, they play right to the bottom, they are so full, tight and just perfectly neutral." This is, exactly my first and lasting impression of these drivers as well and it was great to get the very same unsolicited take on them. It's what's not there that jumps out to me at first.

We listened for a couple of hours and somewhere a track from Pink Floyd's Dark Side of the Moon came through and he stopped and said "Wow! Did you hear that double layer vocal track?! I've been listening to this shit for 30 years and never heard that!" I must confess that I didn't but I was paying far more attention to him, the music was in the background of my focus.

So, like the picture tube or screen that can only be as black as it is when its turned off, in audio, how black is black? I used to largely consider a systems idle noise floor as it's level of "black" but these drivers have shown me that this now reaches deep into my music experience. This is much like the Be loaded driver experience, nothing jumped out at me as for what they do more of, it's what they don't do that makes them well worth the price of admission.

This brings me to something that just came up here and that is the discussion about these new low and ultra low distortion systems seem bass lean to some folks. I really wonder how much of this is driven by what we are just plain used to hearing? Have we learned what to expect from speaker systems that are now far lower in fidelity than what is now available to us from the 1500/1501Al's, and Fe's and 2216's? I know one thing for sure, I'm not looking back.

My friend has 4343's in his living room and has heard plenty of 4350's and other systems to be sure but these knocked him out.

The guys at JBL have really done something here. So often I hear people state with conviction that loud speaker transducers have reached a very mature state of engineering and that is certainly true, the progress is now incremental however, these new ultra low distortion transducers truly have redefined hi-fidelity as I knew it.
I sure wish these could be made widely available I would buy a dozen more if I could get them.

Barry

Calling them 4350s is like comparing a Nascar race car to the street car with a somewhat similar body shape. :D

Next time I'm in your corner of the world I want to hear 'em!



Widget

Hi 1audiohack,

how to reach 20Hz without EQ, with the mentioned drivers?

regards
ivica

Oh man there is so much to chew on in your post, Barry. I laughed out loud when you said that your best room is outside... ain't it the truth. My fairly extreme amounts of room treatment have been an attempt to approach the outdoor condition as much as possible; rooms are evil things. I would encourage anyone who has not done so to haul their system outdoors and prepare to be amazed! Many of my most memorable listening experiences, some stretching back forty years, have been outside.

Add me to the list of those who would really like to hear your hotrodded 4350s sometime. My years of delving into fully compression/horn loaded systems has been mostly an effort to reduce distortions as well as preserve dynamic range. My main complaint with the big boy double 15" JBL and Westlake monitors I have heard is that the bass section has not kept up with the compression horn sections dynamically. I wonder if what I have been hearing is actually the higher THD levels? In some of the white papers I have read it seems that true dynamic compression should not be much of a factor at the levels I would be listening at. Maybe THD is really the thing. Dr. Bruce Edgar has long maintained that to run a direct radiator low end with a horn system one needs to "dirty up the horns" so that THD is not so disparate between the sections. It sounds as though these new generation woofers you've got may be cleaning up the disparity in a better way.

As to rooms loading up, I have noticed more bad vibes in the midrange than the bass. My room has an RT60 of something like 150 ms., while a customer's room with a similar system rings a long time, more like 800 ms. His custom engineered room is beautifully designed in terms of dispersion: no parallel and some curved surfaces, yielding a fairly long but butter smooth "whoosh" with a hand clap. There is a minimum of absorptive materials though, shelves full of LPs mostly, allowing for long reverberant tails caused by the room. On listening to vocals, especially off to one side, there is a strange ramping up and down of levels and a bit of a chorusing effect, like a guitar effects pedal, that I do not hear at home. It is subtle but it intrudes on the listening once one is accustomed to something better. Like I said, rooms are evil.

As to the "lean" low end of a low distortion system, I have been fighting this for years. Most horn systems resolve and sort out bass guitar, kick drum and other low frequency events very well in the listening, but do not offer the comforting THUMP of many direct radiator systems. Virtually all pop recordings were monitored on thumpy direct radiator control room monitor systems, and can sound lean on a truly neutral system.