Jump to content
The Klipsch Audio Community
mikebse2a3

Greg Timbers former JBL designer/engineer 2017 interview

Recommended Posts

Interesting interview touching on several topics and his opinions if you haven't read it'

 

 "For me, Dynamics will make or break the loudspeaker system. Live music is dynamic as hell and this is one of the most difficult attributes to reproduce. Compression exists at all stages of the reproductive and recording chain. Of course, loudspeakers have the most but it is apparent in electronics as well".

 

" I have no use for blind and double blind listening tests the way Harman implements them. Sound systems and their environments are very complicated. No speaker is even close to sounding "real" so personal opinion is always a major consideration. Most blind tests are based on a series of assumptions that enable the test to be easy or practical to implement. Unfortunately, these assumptions often invalidate or color the results because they cover up or accentuate aspects of the loudspeaker design."

 

 

http://positive-feedback.com/interviews/greg-timbers-jbl/

 

 

miketn

 

  • Like 1

Share this post


Link to post
Share on other sites

Nice article. I especially agree about dynamics and room correction. Thanks for sharing.

Share this post


Link to post
Share on other sites

I have read that article before. It is what actually inspired me to go out and purchase 2 pairs of JBL 250Ti's over the past couple years. Coming from a man who personally designed hundreds of products over 40 years, for them to make a his personal top 5 list told me that my own youth era dreams should indeed be validated. Now if I could ever get my hands on Everest models. Probably will never happen for me, but I would settle for M2's LOL.

 

BTW he really got the shafted in the end at Harman. Basically just asked him to come in to the office and handed him his walking papers and escorted out. Other JBL engineers followed him out soon after. 

 

http://www.audioheritage.org/vbulletin/showthread.php?37395-End-of-an-Era-43-years-with-JBL-is-Over

 

 

  • Confused 1

Share this post


Link to post
Share on other sites

I've seen a pic of those speakers somewhere.  The look is exquisite. 

 

Comments from Mr. Timbers sound familiar.  

 

Thanks Mike!

Share this post


Link to post
Share on other sites
2 hours ago, mikebse2a3 said:

"I have no use for blind and double blind listening tests the way Harman implements them. Sound systems and their environments are very complicated. No speaker is even close to sounding "real" so personal opinion is always a major consideration. Most blind tests are based on a series of assumptions that enable the test to be easy or practical to implement. Unfortunately, these assumptions often invalidate or color the results because they cover up or accentuate aspects of the loudspeaker design."

I finally began to understand the issues related to ABX testing of loudspeakers in real rooms--specifically as done by JBL/Harman (and most notably Toole and Olive) when I started into the phase/group delay flattening exercise recently.  I can see why Mr. Timbers might have a problem with the way it was done at Harman. 

 

One of the most egregious decisions that Toole apparently made was to exclude the opinions of classically trained musicians from their ABX testing--something that I believe that Toole should have known better not to pursue.  What Harman ended up with was "self-fulfilling prophecy" of homogenized opinions out the their "certified listener program".  I also talked about this issue in the thread here on the Stereophile review of the Khorn.  The fact of the matter is that there is something about Khorns that seem to attract professional musicians (i.e., classically trained).  Toole apparently screened out that particular group's input into their ABX testing before it could be examined and differentiated from the other group results.  I think that Harman might have produced loudspeaker models more like Greg Timbers was advocating (i.e., more dynamic) over the years rather than where they ended up with consumer grade loudspeakers today (probably excluding the M2).   

 

As far as  Mr. Timbers himself, I find my opinions quite mixed on his overall contributions as a JBL loudspeaker design engineer.  On the one hand, he seems to say many of the same things that PWK and Roy have said about loudspeakers, but on the other hand, the loudspeakers that JBL produced over the years didn't seem to have become household names--and for a number of years now since at least the mid-1980s for sure.  Their professional studio monitor business seems to have shrunk to a mere shadow of what it was in the 1970s (i.e., they didn't stay competitive in that business), and their other "4XXX" series of monitors, loudspeakers, and drivers seems to have lost their edge in the consumer and professional marketplace--apparently very opposite to what has happened with Roy's products at Klipsch, even considering PWK's retirement/passing, and especially the updates to the loudspeakers done much more recently (Forte, Cornwall, Heresy, etc.) which I think are recent marketing successes by comparison.

 

I think a lot of the issue that negatively affected JBL consumer loudspeakers is apparently the cost of doing business, and the cost of their drivers in particular, which have commanded top dollar, but not correspondingly highest performance (this view being reinforced by some of the DSP crossover/REW dialing-in that I've done over the past 2-3 years).  They allowed costs to get out of control, and didn't move the operations from the San Fernando Valley (a huge plant, BTW) to a place where the cost of real estate and income taxes are much more competitive.  I think a lot of what I read on Greg Timber's interview comments revolves around this, based on educated guesses as to what occurred with his termination (i.e., not his fault, but a corporate leadership issue--well above his pay grade). 

 

Chris

Share this post


Link to post
Share on other sites

Regarding the issue of using (or excluding) musically trained folks as listeners:

I had heard that Toole found such listeners to have poor test-retest reliability (and a consistent sensitivity). Although this is not universal across all musician-subjects, it has certainly been noted elsewhere (including labs that I have worked in). 

  • Like 1

Share this post


Link to post
Share on other sites

Instead of excluding the musicians because of "reliability issues", I think that a much closer inspection of what musicians like to hear was the correct path to take. Harman obviously didn't choose that path. 

 

This same situation cropped up in my (prior) line of business: the deeper we looked into the needs of these "unreliable" or "outlier" customer groups, the more reliable they became--once we introduced their needs into our decision models and changed the products that we were considering.  We started to decompose their needs more effectively, and found completely new business areas to pursue--if you catch my drift...

 

Chris

Share this post


Link to post
Share on other sites

I understand where are coming from. However, research is expensive and the name of the game is reliable (consistent) data with as few subjects as possible. I understand the predicament. Now if the goal is exploring some off the main stream  markets, products, or whatever, then certainly I agree with your logic. 

 

I doubt that folks appreciate how expensive and time consuming it is for Harman to run this sort of testing. I think it is remarkable that the Toole-approach can give a decent answer to the question "will folks prefer this speaker to that speaker" based on a handful of  physical measures. In that circumstance, chasing down "other effects" can be hard to justify. 

 

When I was involved in basic research we had the luxury. When I was in applied research, it was more difficult to make a convincing argument to the sponsor (the person writing the check matters ....).

 

Good Luck,

-Tom

Share this post


Link to post
Share on other sites

@PrestonTom I've long appreciated your posts, BTW.   Was that low test-retest reliability with the same part of the same program material?  Do you have info on inter-rater reliability? 

 

In the olden days, when my friends and I were shopping for speakers, we (informally) found that our design/brand preferences tended to be associated with where we sat in the orchestra.  Brass players and those who sat in front of the brass, liked horn loaded midrange/treble.  Percussionists liked fully horn loaded speakers.  Violinists liked Bozak 3way all cone type speakers.  Most of us appreciated the ample bass and small size of the AR-3A acoustic suspension speaker, but all but one of us couldn't stand the muddy, un-dynamic, slow nature of the bass.  The AR3A was reputed to be the flattest, "smoothest" of them all, but that didn't make up for the lack of natural, exciting dynamics and subjectively judged transient response.

 

1 hour ago, Chris A said:

One of the most egregious decisions that Toole apparently made was to exclude the opinions of classically trained musicians from their ABX testing--something that I believe that Toole should have known better not to pursue.  What Harman ended up with was "self-fulfilling prophecy" of homogenized opinions out the their "certified listener program".  I also talked about this issue in the thread here on the Stereophile review of the Khorn.  The fact of the matter is that there is something about Khorns that seem to attract professional musicians (i.e., classically trained).  Toole apparently screened out that particular group's input into their ABX testing before it could be examined and differentiated from the other group results

 

I find it very disturbing that classically trained musicians were screened out of Toole's tests.  The aforementioned orchestra friends and I had a great deal of experience with huge a JBL C55 rear loaded horn enclosure,  equipped with 2 - 15 inch 154 woofers and a 375 compression midrange driver with 537-509 horn-lens (golden and wavy!).  Our favorite record store (mostly classical) used these to demo records, believe-it-or-not.  

image.png.7f5e8b16dabe9a1ba918975bb379ddcc.png

 

So, we heard these speakers about 3 times a month for about 6 years, through long afternoons.  Once in a while we even bought something!  Although these speakers had hardly any deep bass (probably almost nothing below about 50 Hz, best guess), the mid/treble range had incredible, clean but explosive dynamics, and sounded a lot like the orchestra we played in every week-day morning.  If I had to choose between flat frequency response and realistic dynamics, I'd choose the dynamics every time. 

  • Like 1

Share this post


Link to post
Share on other sites

You are asking a very interesting question.

1) in one of the videos by Toole where he talks about his research, he jokingly talks about the "problem" with musicians. You bring them in one day to give numerical ratings to several speakers. Another day you bring them back to do the same thing and the numbers and rank orderings are "different". That is what I meant by test-retest reliability. This finding is not a surprise to researchers (including myself). 

2) The actual numbers were not presented by Toole. 3) The Toole tests allowed the listener to choose their own program material and could listen to it as much as they wanted. As an aside, this issue of not "fixing" the program material raises a number of concerns, but the remedy would only expand the testing to an unmanageable amount (research, and time,  are expensive).

 

It is probably worth noting  that Toole found that positive rating were correlated with 1) Low frequency extension, 2) On-axis frequency response was flat, 3) off-axis response (especially around the cross over point) was comparable to on-axis response (ignore the low frequencies) and did not narrow "too much" as you go up in frequency (IOW, Polars/Dispersion are "smooth" and don't get "too narrow" at the highest octaves. IOW, constant dispersion is a good thing). 

 

Toole's book book goes over this in some detail and is an interesting read. He also has some youtube presentations that are interesting (listen carefully).

 

 In terms of the Greg Timbers interview, there are differences in these two perspectives. This is interesting since they both have very good credentials. 

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...