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Author Topic: Hornless monitor  (Read 1841 times)

Ivan Beaver

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Re: Horn monitor
« Reply #10 on: February 18, 2014, 07:38:52 am »

I agree this looks like the JBL "potato masher" horn with lens system.

It is very strange to see someone using these now, as well as in this form-factor.

Back in the 1970's Tasco Sound (Great Britain) employed this set up but without the perforated plate lens. The result was a very narrow coverage pattern (for MF's and HF's) that was affectionately called the "brain dart". When you were on axis to the HF horn this thing hit you like an ice pick. As long as you kept your head in that very small sweet-spot, you had clear monitors. 

I never figured out why the horn in a separate enclosure was thought to be useful in stage monitor configurations.

Note that JBL describes these as 90 or 60 degrees WITH the perf plates. Without them, the actual horn is somewhere around 20-degrees (conical).

When I was doing sound over a wide geographical area back then, I ran into others using the potato masher HF horns and also larger (4", as in 2441, 2482) drivers with slant-plate and bent-plate lenses. No one had great success with these (in live sound) and JBL dropped them from production after a few years. Having said that, Tasco did use them for at least a few years until something better came along.

Placing perforated plates or slanted/bent plates at the horn mouth (which was also at the surface of the front baffle) may have spread out the otherwise very narrow, focused sound but it also added a huge amount of reflected energy. We all (now) know why this isn't such a great idea.

So I am (again) wondering who has resurrected this idea. And why  ;-)
I don't think that is a current pic.  It looks like Ritchie Blackmore back in the Deep Purple days.  I could be wrong however.
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Ivan Beaver
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Jeff Harrell

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Re: Horn monitor
« Reply #11 on: February 18, 2014, 08:08:07 am »

I don't think that is a current pic.  It looks like Ritchie Blackmore back in the Deep Purple days.  I could be wrong however.
Blackmores Rainbow mid 80's
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Tom Young

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Re: Horn monitor
« Reply #12 on: February 18, 2014, 09:26:16 am »

I don't think that is a current pic.  It looks like Ritchie Blackmore back in the Deep Purple days.  I could be wrong however.

It took me a while to realize that this is an old photograph, Ivan. It is Blackmore and is from the Rainbow days.
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Tom Young
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Scott Helmke

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Re: Horn monitor
« Reply #13 on: February 18, 2014, 10:23:57 am »

It took me a while to realize that this is an old photograph, Ivan. It is Blackmore and is from the Rainbow days.

Almost everything was homebrew back in those days.
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Frank Koenig

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Re: Horn monitor
« Reply #14 on: February 18, 2014, 02:13:44 pm »

As I recall there were folks who removed the annular perforated plates that constitute the acoustic lens which increases dispersion at higher frequencies. This arrangement they termed a "stinger". Looking back this might have been an appropriate name, and not in a good way. -F
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Jay Barracato

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Re: Hornless monitor
« Reply #15 on: February 18, 2014, 02:20:34 pm »

Almost everything was homebrew back in those days.

I can think of a couple places in NYC where they are still in use today...

Sent from my DROID RAZR HD using Tapatalk

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Jay Barracato

Tom Young

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Re: Horn monitor
« Reply #16 on: February 18, 2014, 02:23:09 pm »

Almost everything was homebrew back in those days.

Yes. And they were actually more "works in progress", evolving at a fairly slow pace as we observed things and tried to change them.

Loudspeakers and systems are far further evolved now. As is our understanding of what is going on when we make sound with these systems.

But we still have a ways to go.
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Tom Young
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Art Welter

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Re: Horn monitor
« Reply #17 on: February 19, 2014, 02:37:49 pm »


So a question for the other 'ol timers-how well did they actually work?  The horn mouth is very small for the pattern-and I suspect there would be lots of interference.

I suspect the "masher" part widened the pattern-but at what sonic expense.

About 10 years ago I bought a collection of old JBL horns and drivers which included one potato masher.

Being a single, it didn't sell (plus they never did get a big following) four years ago I cut off the throat at the point where it fit a 2" exit and used it with a spare EV DH1A driver on top of what had been a drum sub.

The response is actually pretty amazing- there are no horns of that depth and size that load as low (312 Hz is the same level as 4-10 kHz) that I am aware of, though there is a huge "scoop" in the 2000 Hz range. The masher's loading also corrects the falling HF response of the driver.

The charts below are the raw response with the masher and driver in a 11.25" x 11.25" x 11.25" box, and the same with a passive crossover, which IIRC only uses a capacitor, coil and two resistors for the HP section.
Took a lot of parts juggling, never would have got it that smooth with what I knew in the late 1970's when these were (somewhat) popular.
The sensitivity works out so the nominal 16 ohm HF masher/crossover is about equal to a 15" which is about 98 dB midband.

The measurement distance was about 2 feet, the distance the potato masher is from a drummer's ear sitting on top of the angled 15" speaker cabinet.
As others have mentioned, these are "short throw" devices, the sound does not hang together too well outside a relatively small "bubble".

Hey Jeff- want to buy a drum monitor?

Art
« Last Edit: February 19, 2014, 02:49:06 pm by Art Welter »
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Jeff Harrell

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Re: Horn monitor
« Reply #18 on: February 19, 2014, 03:48:59 pm »

About 10 years ago I bought a collection of old JBL horns and drivers which included one potato masher.

Being a single, it didn't sell (plus they never did get a big following) four years ago I cut off the throat at the point where it fit a 2" exit and used it with a spare EV DH1A driver on top of what had been a drum sub.

The response is actually pretty amazing- there are no horns of that depth and size that load as low (312 Hz is the same level as 4-10 kHz) that I am aware of, though there is a huge "scoop" in the 2000 Hz range. The masher's loading also corrects the falling HF response of the driver.

The charts below are the raw response with the masher and driver in a 11.25" x 11.25" x 11.25" box, and the same with a passive crossover, which IIRC only uses a capacitor, coil and two resistors for the HP section.
Took a lot of parts juggling, never would have got it that smooth with what I knew in the late 1970's when these were (somewhat) popular.
The sensitivity works out so the nominal 16 ohm HF masher/crossover is about equal to a 15" which is about 98 dB midband.

The measurement distance was about 2 feet, the distance the potato masher is from a drummer's ear sitting on top of the angled 15" speaker cabinet.
As others have mentioned, these are "short throw" devices, the sound does not hang together too well outside a relatively small "bubble".

Hey Jeff- want to buy a drum monitor?

Art
Not right now. i use headphone like drummer  Nigel Olsen. i aslo have 2 more of these in the foto just in case-a-dia i want to ditch the headphones. BUT and thats a BIGG BUTT i will keep you in mind if i decide to try out that horn. the thing with me is i dont keep my head in one spot whem playing, i move it from side to side and stuff. how large in diameter is the listening window of that horn ?
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Russ Davis

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It's Blackmore! Duck!
« Reply #19 on: February 19, 2014, 04:51:44 pm »

Ritchie looks less sullen than usual here, but I'm curious as to what exactly is going on...  Is he accepting an upside-down beverage from a fan (and possibly using it as a leaky slide), or is he dumping his drink on the punters' heads?
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