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EQ and monitoring

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Re: EQ and monitoring

PostPosted: Tue May 26, 2020 12:19 pm
by zenguitar
Dub til you drop wrote:So you take the back off the bass, and a load of spiders and and pieces of potentiometer drop out.

If that happens, you would have a bass that already wasn't working and you would never get to hear the crackling socket.
:)

Andy :beamup:

Re: EQ and monitoring

PostPosted: Tue May 26, 2020 1:27 pm
by Tim Gillett
Hugh Robjohns wrote:
Tim Gillett wrote:If we are making comparisons between one speaker and another, this is meaningless.

I suspect what's really meaningless is comparing the views of those that have actually heard the speakers in question, and those that are only reading the manufacturer's vintage literature...

:roll:

I listened extensively through JBL monitors in the control room of Studio B, Planet Recording Studios, Perth in 1988. Charis, a band I was in at the time recorded an album there. Planet were then Perth's premier recording studios.

Re: EQ and monitoring

PostPosted: Tue May 26, 2020 1:39 pm
by Hugh Robjohns
Odd. Why would you say:

Tim Gillett wrote:I've just been reading up on the old JBL 4320 studio monitors. From the published specs its hard to believe they would have sounded harsh...

...if you have direct personal experience of them?

Wouldn't someone with that experience instead offer something more like, 'I didn't find them harsh at all when I listened at Studio B...'

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 1:12 am
by Tim Gillett
Hugh Robjohns wrote:Odd. Why would you say:

Tim Gillett wrote:I've just been reading up on the old JBL 4320 studio monitors. From the published specs its hard to believe they would have sounded harsh...

...if you have direct personal experience of them?

Wouldn't someone with that experience instead offer something more like, 'I didn't find them harsh at all when I listened at Studio B...'

Lots of memories of those sessions. But I'd forgotten the monitors were JBL's. Tony's linked pictures reminded me. It's a long time ago but I do recall finding them excellent. Smooth, wide range, not harsh. But anybody could claim I was mistaken and they could be right. Then again, they could be mistaken.

Hence my referencing what seems like an objective set of measurements, obviously pitched by JBL to the pro audio industry - a risky business move if the data turned out to be false? - and I for one have no good reason to question its validity.

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 1:46 am
by James Perrett
Tim Gillett wrote:Hence my referencing what seems like an objective set of measurements, obviously pitched by JBL to the pro audio industry - a risky business move if the data turned out to be false? - and I for one have no good reason to question its validity.

Manufacturers were known for being optimistic - which is probably why all the decent magazines of the time included fairly detailed measurements in their reviews.

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 2:05 am
by Tim Gillett
Yes and a good thing manufacturers' claims could be cross checked independently as we hope they are today also. So did independent testings in fact show JBL's specs to have been inaccurate?

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 2:10 am
by innerchord
I stand by my comment about those brochure specs looking a bit of a joke, but don't forget that the speaker is often not the only frequency shaping component in the monitoring chain.

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 2:18 am
by Tim Gillett
Not sure what you mean by that innerchord. Can you explain?

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 5:01 am
by innerchord
Sure. I made two points.
1) As it reads, the information below the frequency response plot in the brochure states that all production models of the JBL fall within 2dB of the curve. The (rather artificial-looking) curve strays -1dB at 1kHz, and +1dB at 7kHz. Thus a production speaker could be -3dB at 1kHz and +3dB at 7kHz. A 6dB difference between those frequencies could certainly be perceived as sounding harsh. It may be a typo, and they meant that production speakers are within 2dB of flat, as in the example plot.

2) It was and still is standard practice to use frequency compensation to account for room and speaker issues, so it's quite possible that a set of bright-sounding JBLs have been EQ'd to sound "smooth".

My experience with JBLs from the 80s/90s is definitely hearing the "smile" type of curve.

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 10:59 am
by cyrano.mac
There's definitely a "JBL" sound...

But we're avoiding the elephant in the room: The Room.

Speakers can sound wildly different, depending on placement and room acoustics. Putting those JBL speakers on a wooden floor would sound different from having them flush mounted in a tuned studio setup, wouldn't it? Etc. etc...

And I always seem to need time. Lots of it before I know any speaker in any room. Listening in a showroom, fi, is worthless, for me.

Re: EQ and monitoring

PostPosted: Wed May 27, 2020 5:23 pm
by Hugh Robjohns
Tim Gillett wrote:I'd forgotten the monitors were JBL's. Tony's linked pictures reminded me. It's a long time ago but I do recall finding them excellent. Smooth, wide range, not harsh.

Fair enough... An opinion based on direct experience is as valid as any other.

Hence my referencing what seems like an objective set of measurements

But a very limited set of measurements that are missing any detail at all on harmonic distortion levels relative to frequency... which would give some valid indication of perceived harshness.

It may be an ear-training thing, but most British engineers of the era that I've met have commented onthe large American studio monitors sounding harsh and abrasive in comparison to the home-grown systems of the day.

And personally, I've not found any large JBL monitor rigs of that era (or most later ones, to be honest) that sound anything like natural to my ears. Those compression-horn drivers with 'acoustic lenses' could certainly go loud, and the directivity was well controlled, but natural sounding they were not -- at least, not to me!

A decade or so ago I was astounded to discover that MeyerSound's X10 studio monitor used a compression driver because it sounded as smooth and natural as a dome tweeter to me. It turned out that John Meyer had spent many years (and a lot of money) developing it to overcome what he explained were the inherent problems of standard compression drivers, achieving significantly lower levels of distortion.

Clearly, YMMV.

Re: EQ and monitoring

PostPosted: Thu May 28, 2020 3:29 am
by Tim Gillett
Hugh Robjohns wrote:
Tim Gillett wrote:I'd forgotten the monitors were JBL's. Tony's linked pictures reminded me. It's a long time ago but I do recall finding them excellent. Smooth, wide range, not harsh.

Fair enough... An opinion based on direct experience is as valid as any other.

Hence my referencing what seems like an objective set of measurements

But a very limited set of measurements that are missing any detail at all on harmonic distortion levels relative to frequency... which would give some valid indication of perceived harshness.

It may be an ear-training thing, but most British engineers of the era that I've met have commented onthe large American studio monitors sounding harsh and abrasive in comparison to the home-grown systems of the day.

And personally, I've not found any large JBL monitor rigs of that era (or most later ones, to be honest) that sound anything like natural to my ears. Those compression-horn drivers with 'acoustic lenses' could certainly go loud, and the directivity was well controlled, but natural sounding they were not -- at least, not to me!

A decade or so ago I was astounded to discover that MeyerSound's X10 studio monitor used a compression driver because it sounded as smooth and natural as a dome tweeter to me. It turned out that John Meyer had spent many years (and a lot of money) developing it to overcome what he explained were the inherent problems of standard compression drivers, achieving significantly lower levels of distortion.

Clearly, YMMV.

So harmonic distortion from the horn driver. Tha's a lot more targeted than just mention of "harshness". Certainly no amount of EQ can fix that. It would have been good to have the harmonic distortion analysis, and I guess the test results would have been essentially the same on either side of the Atlantic...

The only reference I have here for distortion is in Tremaine's Audio Cyclopedia (rev 1969)
He speaks of "up to 17% second harmonic distortion with a power of 1 acoustic watt from the driver unit." But that appears to have been written before the release of the JBL monitor we were discussing. Maybe JBL had made progress in that department since then. I understand JBL invested heavily in R & D with compression horns.

I'm reading a review of the MeyerSound X10. A lot of detail about innovations with a single woofer using "an advanced feedback circuit" with input from UC Berkeley but precious little about the horn, as if he was basically using standard horn technology of that time. If Meyer had been doing something new with the horn it seems strange nothing was said about it in the article.

https://www.mixonline.com/technology/me ... tor-369865

Re: EQ and monitoring

PostPosted: Thu May 28, 2020 7:54 am
by Arpangel
I’ve always loved the "JBL sound" I’ve recorded in studios that have had smaller versions of those in that picture, and they do have a family sound.
I went to a pro-audio show in London (APRS?) show back in the 70's and I heard those big JBL's for the first time.
I wouldn’t in any way describe JBL's as being harsh, they do have a presence peak though that makes them sound "exciting" and they are the only speaker I’ve come across that comes even vaguely close to achieving that holy grail, when you walk from the live room into the control room it still sounds like the band, and at the same volume, that’s why they were preferred by rock producers back in the day.

Re: EQ and monitoring

PostPosted: Thu May 28, 2020 10:55 am
by Hugh Robjohns
Tim Gillett wrote:So harmonic distortion from the horn driver. Tha's a lot more targeted than just mention of "harshness".

Equating technical descriptions with underlying causes has always been a problem. But it seems natural to me that harshness = distortion. If it had been a simple EQ problem I would have commented on it being bright, or maybe forward sounding.... But to me, those old JBL studio monitors sounded 'harsh', meaning they introduced audible HF distortions.

I understand JBL invested heavily in R & D with compression horns.

They needed to -- along with every other manufacturer of horn drivers -- but I understand reducing distortion in compression drivers was a very difficult nut to crack because of the inherently non-linear behaviour of modulating air as a sound medium at high pressures.

That's why I was so surprised and impressed with what Meyer had achieved when I first heard the X10 in the run up to Christmas 1999.

...but precious little about the horn, as if he was basically using standard horn technology of that time. If Meyer had been doing something new with the horn it seems strange nothing was said about it in the article.

Meyer had used standard JBL compression drivers in a lot of their PA speakers up to the late 90s, as there wasn't really much alternative. However, his company often rebuilt them to improve their performance, and learned a lot about the technology in the process.

But when Meyer was commissioned to build a PA system for an Opera House it became clear that these existing horn drivers just weren't good enough for the job, and that's what started John down a development path to build a fundamentally better compression driver of his own design.

The compression driver in the X10 was essentially his second-generation design, so he really wasn't using 'standard horn technology'. And it's not really strange that the information is limited: I had to sign NDAs when I first went to see and hear the X10 prototype, and I continued under those NDAs when I was subsequently commissioned to write up a lot of the public-facing and internal company documentation on the project. It was all genuinely pioneering stuff that involved a lot of commercial secrets.

In brief, and within the bounds of what I can say about it publicly, John and his R&D team managed to create bespoke innovative compression horn drivers that produced well below 0.2% THD at 90dBSPL -- directly comparable to dome drivers -- but these drivers were able to maintain very low distortion levels even at continuous SPLs far beyond the capabilities of any dome tweeter.

For comparison, typical compression drivers (at that time, anyway -- I don't know how the technology has been advanced by other manufacturers over the last 20 years) produced around 1.5% THD at 90dBSPL. That kind of distortion might be acceptable when working at PA levels with the driver pushing out 130dB plus, but it clearly isn't in a quality studio monitor that probably spends most of its time working around 85dB SPL or so (in large professional control rooms).

The Meyer R&D team spent two years developing their compression driver, starting with a 3-inch unit because they had the facilities to stamp the complex diaphragm shapes and had suitable magnetizers on site. The final design involved an innovative alloy and bespoke shape for the diaphragm, as well as a clever hybrid suspension which was much quieter and introduced massively less distortion than conventional solutions.

They then scaled this driver design up to a four-inch model which had a greater bandwidth and could be coupled to a 15-inch bass driver in a two-way design. (The 3-inch couldn't go low enough to achieve a viable two-way crossover with a 15-inch bass unit, and was generally used with 12-inch bass drivers).

Much of the driver's performance gain, though, was down to the design of the compression throat feeding into the horn, and John worked with the Jet Propulsion Lab as only they had the technology and experience to analyse the behaviour of air at high pressures in confined spaces!

Re: EQ and monitoring

PostPosted: Thu May 28, 2020 2:49 pm
by Tim Gillett
Thanks Hugh, very interesting. It may just be the Mixonline article but I don't understand why they didn't at least mention and even boast about the significant reduction in HF THD they had achieved while (of course) not disclosing just how they achieved it.