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Author Topic: Factory Speaker Specs & Grilles  (Read 15155 times)

John Roberts {JR}

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Re: Factory Speaker Specs & Grilles
« Reply #20 on: December 03, 2015, 02:11:10 pm »

But did it sound better? :)
Actually there is an audible component to an unfettered air intake. Often drowned out by exhaust system noise but not always.

When I was a hot-rod kid, a friend of mine made his own DIY intake manifold to mount 3 one barrel carbs on his inline 6 (1953 Ford). That motor made more carb noise than exhaust rumble. Didn't go very fast compared to V8 motors of the time, but sounded pretty good with the intake in full honk.  8)

JR
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Steve M Smith

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Re: Factory Speaker Specs & Grilles
« Reply #21 on: December 03, 2015, 02:49:09 pm »


Interesting point. I don't see many, if any, square hole speaker grills.

No. It's usually round or hexagonal. Obviously hexagonal has more open space than round, although you might be able to reduce the spacing between the apertures as it will be wider elsewhere. 

I have some Peavey UL115 subs which have square perforated grills but I can't think of any others.


Steve.
« Last Edit: December 04, 2015, 01:56:53 pm by Steve M Smith »
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Jim McKeveny

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Re: Factory Speaker Specs & Grilles
« Reply #22 on: December 04, 2015, 07:35:01 am »

Another is the reflections off of the back of the grill-back into the speaker-and then causing combfiltering-due to the multiple arrivals.

Besides throttling HF, reflections back-to and off-of baffle because of perforated/expanded metal could be seriously disruptive. I imagine JBL Vertec (+ others) leaving MF/HF uncovered is not just a styling exercise, but also good practice.

It would be nice if those mfrs. with serious measurement and preset research (L'Acoustics, JBL, D&B) could chime in here.

Otherwise, bring back grille cloth!
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Jim McKeveny

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Re: Factory Speaker Specs & Grilles
« Reply #23 on: December 04, 2015, 07:47:35 am »

When I was kid we used to take the air cleaner off our car engine to make it faster...

If a choked airflow was a major limiting factor you did. You also introduced all kinds of airborne grit into the engine, causing premature valve & bore wear. Air filter assemblies are also a backfire flame arrestor ('cepting the really old oil-bath "cleaners" I imagine).

So overall a typically brilliant youthful idea...
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Keith Broughton

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Re: Factory Speaker Specs & Grilles
« Reply #24 on: December 04, 2015, 08:01:52 am »

Besides throttling HF, reflections back-to and off-of baffle because of perforated/expanded metal could be seriously disruptive. I imagine JBL Vertec (+ others) leaving MF/HF uncovered is not just a styling exercise, but also good practice.

It would be nice if those mfrs. with serious measurement and preset research (L'Acoustics, JBL, D&B) could chime in here.

Otherwise, bring back grille cloth!
As I understand it, when Danley did some tests regarding grill foam on the TH115 subs, they found it made a measurable difference.
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Ivan Beaver

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Re: Factory Speaker Specs & Grilles
« Reply #25 on: December 04, 2015, 08:17:08 am »

As I understand it, when Danley did some tests regarding grill foam on the TH115 subs, they found it made a measurable difference.
It was the combination of the cloth and the metal grill that affected the LF response.

The cloth makes no difference on the full range products.  The exit are is much larger.

But on the tapped horns, it did "choke off" the response.

But we need the grill for protection.

NOW-Let's look at the REALITY.

I don't have measurements to show-and can get some when I get back in the office-if I find some time.

Yes the HF response is reduced a little bit because of the open area of the grill.

But how MUCH is the question, and will the average person even notice?

Once you get a decent distance away-the air absorption is going to be the biggest issue-and a grill or not is simply not going to be heard.

Just like if I pee into a lake.  Technically the lake level rises.  But is it enough to be concerned with?

Sometimes people get "hung up" on things that don't make any real difference, yet let "the big issues" go right on through.

So let's go back to reality.  Suppose the HF is reduced because of the grill.  If you want that HF you will simply eq it as needed.

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Bob Leonard

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Re: Factory Speaker Specs & Grilles
« Reply #26 on: December 04, 2015, 08:22:24 am »

I have to think anything that disrupts the flow of air will make a measurable difference. but I would also have to believe that reputable manufacturers take that into consideration during the design and test phase. That's also my reason for not placing too much emphasis on grill appearance or design when making purchasing decisions.

EV used, and probably still uses, foam grill backing to their advantage, the Sx500+ being a prime example. That cabinet has a round piece of 1/4" foam directly over the middle of 15" driver. I owned 1/2 dozen of these at one time in my life, and thinking the cabinets would sound better with the foam removed I experimented on a pair of them. Having untouched cabinets to compare side by side opened my eyes, and the result of removing the foam did exactly what I thought it would. It opened up the midrange response, but to a point where mid range honk was introduced. I could almost EQ the cabinet back to the original sound with all of it's smooth response and glory, but close is not good enough, and the effort to EQ the cabinets far out weighed the benefits. Needless to say the foam was put back on to the grill and that experiment chalked up to experience.
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Keith Broughton

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Re: Factory Speaker Specs & Grilles
« Reply #27 on: December 04, 2015, 09:27:42 am »

\
Sometimes people get "hung up" on things that don't make any real difference, yet let "the big issues" go right on through.

So let's go back to reality.  Suppose the HF is reduced because of the grill.  If you want that HF you will simply eq it as needed.
The concern about the grill is minor when you end up forced to have so called "blow through" hung in front of your speaker system!
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John Roberts {JR}

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Re: Factory Speaker Specs & Grilles
« Reply #28 on: December 04, 2015, 09:35:35 am »

If a choked airflow was a major limiting factor you did. You also introduced all kinds of airborne grit into the engine, causing premature valve & bore wear. Air filter assemblies are also a backfire flame arrestor ('cepting the really old oil-bath "cleaners" I imagine).

So overall a typically brilliant youthful idea...
Back in those days I would break my engines well before they came close to wearing out, and they didn't start out new, just put the cam and heads on a different (used) short block and we're ready to rumble.

One night I experimented with connecting the heater fresh air intake tube, to the air filter housing intake. So I had cold air running direct into the top of the carb. Motor was running really good that night until I threw a rod, cutting my oil pan in half... :'(

I do not advocate running without an air filter and these days run K&N low resistance air filters. 8)  I even used an air filter in front of the supercharger I put on one car.

JR

PS: For live sound use I'm inclined to trust the manufacturer to design for use with the grills in place. If you think you're smarter than the manufacturer, you probably aren't.
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Andre Vare

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Re: Factory Speaker Specs & Grilles
« Reply #29 on: December 04, 2015, 12:09:57 pm »

Lots of research and effort goes into the design of cones & drivers & dsp correction & amplification to produce nice spec'ing pro loudspeakers, but then we clamp reflective 60% open-area (i.e. 40% blockage) metal grilles on everything. I imagine these cause measureable response aberrations.

Surprisingly, well not for acoustics, the percent open area is not that significant.  What is important is the size of the web material between the openings.  For the quick and dirty have a look at examples 1 and 2 on pdf pages 20 and 21 of http://www.iperf.org/files/1313/9265/8912/The_Acoustical_Uses_for_Perforated_Metals_Handbook.pdf.  The metal with 53% open area increase over the first example has 2 dB greater attenuation than the smaller percentage open area! Of course the rest of the document goes into more detail.

Andre
« Last Edit: December 04, 2015, 12:13:08 pm by Andre Vare »
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Re: Factory Speaker Specs & Grilles
« Reply #29 on: December 04, 2015, 12:09:57 pm »


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