Greg Timbers interview.

[tom1040]

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

[Flodstroem]

Thanks Tom for posting this. Amazing :)

[Ed Zeppeli]

Interesting article. Thanks for posting.

From the comments Greg describes his system(s) and gives clues to what he looks for when eqing.

My system consists of the following:
2-channel:
Everest DD67000, fully active 4-way
DEQX HDP4
DEQX Premate
Pass Labs XVR1
Parasound JC1, 4 amplifiers, 1 for each woofer.
Quicksilver Mono 120, 1 for each large compression driver
Pioneer Elite A-20, for UHF compression driver
Pass Labs XP-15 Phono Stage
Basis Audio Debut Turntable with SuperArm 9 and Dynavector DV-20x
Tascam DA-3000, Digitizing LP's
MacMini running JRiver Media Center 22
PS Audio LanRover
4 channel, All of the above plus:
K2 S9900, fully active 2-way
Pascal M-Pro amps within the speakers
DEQX Premate for crossover and DSP
Classe Audio CT-SSP
Oppo BDP-103
Oppo BDP-203
JVC RS-600 Projector
Stewart Film 110" Firehawk, 2.40:1
LG 65" OLED
All speaker cables and audio interconnects are StraightWire Virtuoso
5 microphone array around listening position shows -3 dB @ 20 Hz and -6 dB @ 48 kHz. The 1/6 oct response of the 5 microphone average is less than +/- 1 dB from my target curve over that range. The system sensitivity (if passive) would be 96 dB for 2.83 v @ 1 m. Since the DEQX uses linear Phase (FIR) crossovers, I have the impulse of each individual transducer and its network aligned to less than 0.1 ms at the listening position. EQ and room correction is done in the DEQX, JRiver and the CT-SSP depending on input and overall system configuration. (Music, Phono, Movie}

[rdgrimes]

For posterity, some stereo porn:

76289
76290
76291

[Hoerninger]

Tom1040, thank you for setting a link to this fine interview.
___________
Peter

[Mr. Widget]

Thanks Tom... very interesting. It is so nice to hear such a reasoned voice in audio.

I am still all analog, but am definitely tempted by the power of digital. On a side note, I found it interesting that he also picked the Parasound Halo JC1 amps... they really control these massive JBLs. Two provide unholy headroom, I'm sure he is using two per side simply for individual driver control, but damn! That is insane headroom.


Widget

[JeffW]

What's the white thing on the wall above the turntable? Looks too complex to be a simple light fixture.

[Mr. Widget]

What's the white thing on the wall above the turntable? Looks too complex to be a simple light fixture.Looks like a lamp to me.


Widget

[srm51555]

Tom1040, thank you for setting a link to this fine interview.
___________
Peter
+1

[WKM]

Does anyone know what Timbers means by "esoteric discrete stuff"?

By using FIR filters, amplitude and phase can be manipulated independently so this constraint can be overcome. The hardware in the DEQX is very well implemented indeed, but it is no match for the esoteric discrete analog stuff. Still, the complete amplitude and time correction easily overcomes this handicap and has given me the best of both worlds. I now have all of the detail, dynamics, smoothness and spacial attributes I have been searching for with the ability to do room correction and frequency shaping as I wish. It is a win-win for me.

[grumpy]

I read it as high quality/performance analog electronics, with "discrete" normally indicating circuits built from individual parts that each perform a low-complexity function (e.g., a "discrete" op amp is built from individual transistors, resistors, capacitors, etc... vs an integrated circuit version... which can also work quite admirably).

[speakerdave]

Bryston crossovers are discrete, but I'm guessing he meaneth Pass Labs.

I knew a guy, a salesman at Eber Electronics in San Francisco, back in the day. He would sometimes say, "That's good enough for anybody." Comes to mind for some reason.

[DavidF]

Thanks Tom... very interesting. It is so nice to hear such a reasoned voice in audio.

I am still all analog, but am definitely tempted by the power of digital. On a side note, I found it interesting that he also picked the Parasound Halo JC1 amps... they really control these massive JBLs. Two provide unholy headroom, I'm sure he is using two per side simply for individual driver control, but damn! That is insane headroom.


Widget

He mentions using 4-way configuration. That could suggest distinct signal feed with a different roll-off on each woofer, perhaps?

I like the reference to the Pioneer A20 amp to drive the UHF among all the other goodies. I recall him mentioning using a lowly 70's era Kenwood integrated in a similar configuration in one of the earlier 4-way models.

Also, he is looking pretty fit in retirement, aint he?

[pos]

Funny to read that he is now using the 045, even in a fully active setup.
It was disconnected in his former array 1200, but that might be due to the narrower horizontal nominal directivity of the vertical horn that, together with the slot, made the directivity behavior more consistent up to the UHF...

[bubbleboy76]

Funny to read that he is now using the 045, even in a fully active setup.
It was disconnected in his former array 1200, but that might be due to the narrower horizontal nominal directivity of the vertical horn that, together with the slot, made the directivity behavior more consistent up to the UHF...

Sounds plausible! That is the main benefit of vertical horn maybe?

Was he passively aggressively dissing M2 when he said plastic membranes almost never works?

Funny to read about the FIR-stuff he now uses, and the benefits it gives according to him. Damn, I probably have to get me a couple of OpenDRC again!

I would really like to play with an DEQX as well. Have you tried it pos?

[Flodstroem]

Damn, I probably have to get me a couple of OpenDRC again!

I would really like to play with an DEQX as well. Have you tried it pos?

A group buy maybe for the DEQX? :blink:

[audiomagnate]

He wants to play with ribbons!

[hjames]

Very neat interview - tho I had to notice this aside ..
When asked
if you could go back in time, any speakers that you would do differently?
The only big mistake on my part was the L212 system. I was working on it at the time we were moving from Glendale to Northridge.
The measurement facilities were up and down at both locations and listening rooms were at both places so there was no consistency to any of the results.
I made a tactical error that made the system less than it deserved to be.

I just refurbed a pair of the L212 towers around Christmas, I like the combination of drivers and really enjoy the sound of these speakers,
(although the seller did not offer the original sub B212 Bass unit, so I made do with a Volkswoofer I already owned),

but I'd love to know more about what "tactical error" or compromises might have been made ...

[pos]

I would really like to play with an DEQX as well. Have you tried it pos?
Never tried them :dont-know:
I am eagerly waiting for Tranquility Bass' solution (http://www.diyaudio.com/forums/digital-line-level/264743-hi-end-dsp-based-multi-channel-integrated-preamp-crossover-dac-project.html) right now, enjoying my openDRC's in the meantime ;)

[pos]

I just refurbed a pair of the L212 towers around Christmas, I like the combination of drivers and really enjoy the sound of these speakers,
(although the seller did not offer the original sub B212 Bass unit, so I made do with a Volkswoofer I already owned),


but I'd love to know more about what "tactical error" or compromises might have been made ...


http://www.audioheritage.org/html/perspectives/smith.htm



The original concept for the L212 was devised by Ed May, but he left JBL before the system was developed. Lorr Kramer, Greg Timbers and Terry Sorenson were responsible for engineering of the production model. Terry was a fun guy, one of the crew when I was there. Terry was studying for an MBA at night so he would frequently come in and preach the Religion-of-the-Free-Market to us. Engineers like to debate so that was as good a topic as any.

Anyhow the 212 had a removable base that, once removed, allowed the system to be buried flush in the pit. The crossover was designed to give a highly flat system under those conditions. Unfortunately once removed from the pit the 2pi to 4pi effect was enough to mess up the response to an appreciable degree. Not that it was horrible sounding, just that it wasn't the balance you would have given it if you thought about it. I remember that the system was reviewed by High Fidelity. They used CBS labs for measurements and did a Floyd Toole type axial response/front hemisphere/total sphere set of measurements. Sure enough the response showed a pretty good mound around 200Hz (the secondary effect) that the reviewers commented on. I don't remember if a running change was made to fix it, but at least a lesson was learned that 2pi flat was not the answer and no later systems fell into that trap. This was one of the main incentives for developing the ground plane measuring technique.

By the way I had one of the 212 systems and liked it a lot. It used great drivers including the very expensive 112A mid bass unit. This was the only 8" JBL driver to use a 3" coil. Terry showed me a 3 element passive notch circuit that was developed to fix the response and so it sounded quite good. When I moved to KEF in the UK, this is the system I took with me (I sold my KLH 9's to Randy Patton).

[Mr. Widget]

Thanks pos. Not sure if I forgot that page or never stumbled upon it before.


Widget

[hjames]

http://www.audioheritage.org/html/perspectives/smith.htm

Sure - I read that David Smith page at Christmas when I did all my research on the system as I was rebuilding the mid-woofers and such,
(Google is very helpful) but I was sort of hoping maybe Greg Timbers would give HIS thoughts on the system ...

I can recall some discussion in the forums in the past where someone had mentioned taking the feet off the towers
and possibly wall mounting them - and of course the various thread on stacking multiple pairs of them.

But - this is a thread about Greg Timbers ...

[bubbleboy76]

Never tried them :dont-know:
I am eagerly waiting for Tranquility Bass' solution (http://www.diyaudio.com/forums/digital-line-level/264743-hi-end-dsp-based-multi-channel-integrated-preamp-crossover-dac-project.html) right now, enjoying my openDRC's in the meantime ;)

Hmm, I see it now will take multichannel digital input in i2s format. Interesting for me, because the new VanityHD for Oppo 203 will probably output 8 channels i2s. This would be the perfect system for me!
tranquility bass will still be ready "any year now"? ;)

[sweet212]

Hmm, I see it now will take multichannel digital input in i2s format. Interesting for me, because the new VanityHD for Oppo 203 will probably output 8 channels i2s. This would be the perfect system for me!
tranquility bass will still be ready "any year now"? ;)

Yes thank you you Mt Timbers - I loved your work - a true genius.

GT stresses the importance of high efficiency for dynamics. In my lifetime of owning many JBL's - high efficiency JBL's have been the ones I turn down in volume. Whereas the low efficiency have always wanted to turn up.

Mr Timbers says that he made a mistake with the 212's. Well to me they were the best sounding JBL's I've ever owned! Sure they're colored and when pushed were dirty. Male vocals were chesty - mids were a little honky and highs were over emphasized but just glorious. The colorations were a plus IMO!

[DavidF]

The Everest enjoying pride of place in Greg's listening room. Anyone have an idea of the dimensions of the room?

http://positive-feedback.com/wp-content/uploads/2017/03/gt3.jpg

[grumpy]

From my poor recollection it's what you can see in the pic and maybe 2.5x longer with a listening seat/couch
at the 2x dimension (verry very roughly). Perhaps someone else recalls better. It sounded swell :D
(prior to the DEQX, JC-1 room heaters, and some of the other goodies).

I thought the tweeter amp was something like a Marantz 1060.
Whatever it was, it either did the job or was unimportant to my ears :)

[Goldjazz]

Interesting interview. I like his, no nonsense, insights. His comments about vintage vs present day loudspeakers are succinct and correct. Satisfying to read when someone hits the nail on the head like that, it neatly wrapped up a few of my thoughts and observations I had on the topic.

[Titanium Dome]

It took five days, but my comment on the article was finally approved. Maybe I was ragging on Harman a little too much? To Posi+tive Feedback's credit, nothing was edited out.

The article is linked and Greg is quoted on the DEQX site for those who love this kind detail.

[JeffW]

Your comment appeared there when I first viewed the article some days ago, not sure why it's just showing up for you.

Re DEQX, here's a take from a guy (http://www.audioheritage.org/vbulletin/showthread.php?29281-Some-thoughts-on-Deqx-and-their-products) who spent more time and money on them than most here:


The Deqx was never intended to be a DIY product? I have been told they dislike that it is. It was designed by the same people who designed the Dolby Lake Contour. The two products are similar. The Dolby was for the Pro Sound Market and the Deqx for the OEM Speaker Manufacturing Market. It was designed by engineers for engineers. That being said, it would not surprise me if the DIY market has kept them solvent while they continue to court the OEM's. The company will sell to the DIY market, as evidenced by looking at their website, but appear to have minimal interest in supporting it. Hence, the self- serving comment. Common guys, commission someone to create a usable instruction manual. You owe it to us.

[LowPhreak]

Maybe I was ragging on Harman a little too much?

Ehh...I don't think it's possible to rag on Harman too much. :nopity::D

[Mr. Widget]

Your comment appeared there when I first viewed the article some days ago, not sure why it's just showing up for you.Ditto... and well put too. :)


Ehh...I don't think it's possible to rag on Harman too much. :nopity::DSad but true.


Widget