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Old 23rd June 2017, 07:29 AM   #1
Mrscy is offline Mrscy
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Default ROAR18

Hi all, i have great interest in the ROAR18 design. The simulation looks very impressive. What do you think of it?

Link to proposal: Martinsson's Blog - ROAR18
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Old 23rd June 2017, 03:47 PM   #2
just a guy is offline just a guy  Canada
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Personally I don't like it at all, for all the reasons previously discussed in the previous thread. That huge 20 db dip right above the passband is going to cause all kinds of problems with proper crossover implementation. The terminology they use is made up, the whole thing is a 1/4 wave resonator, not just the big bit at the mouth. The frequency response is terrible and will just get worse with power compression. They claim this huge dip right outside the passband is a benefit - but it certainly is not.

Circlomannen and Martinson latched onto this idea when trying to figure out how the Danley sub works. Needless to say their ideas about a velocity wave creating an extra segment in front of Danley's horn out of thin air was ridiculous, as was the notion that Danley's frequency response looks anything like this thing, or even that the Danley sub was a tapped horn. (It's not.) Their analysis of Danley's horn was remarkably off base and their analysis of this type of creation is equally off base.

You can get the same frequency response with a much more traditional looking flare, although I have no idea why you would want to because it's terrible.

I'm sure it makes a lot of noise though.
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Old 23rd June 2017, 08:10 PM   #3
Circlomanen is offline Circlomanen  Sweden
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ROAR12_and_linesource.jpg

My Roar12 is comparable to a THAM15 in both max spl and usable frequency response.

It has a more physical character. Where the Tham15 has a slightly better attack, the Roar12 will make stuff rattle and jangle with lots of energy in the lower part of its passband. A B&C 12PS100 seems to have roughly the same max spl in a Roar12 as a B&C 15PS100 in a Tham15.

https://youtu.be/xZ227k8Gf9U?t=25

My oldest son has a lot of fun with my Roar12 and a 10 watt cheap class D amp.
When standing close to the mouth of the Roar12 the bass pulses feels quite unpleasant in your chest (with only 10 watts).

Cheers,
Johannes
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Last edited by Circlomanen; 23rd June 2017 at 08:13 PM.
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Old 2nd July 2017, 04:04 AM   #4
Mrscy is offline Mrscy
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In terms of sound quality, how does the Roar12 sound? i have heard a THAM15, one thing i love about it is that produces very musical bass notes.

2. Is the ROAR series easy on the driver, isnt the compression too high?
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Old 2nd July 2017, 09:51 AM   #5
martinsson is offline martinsson  Sweden
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S1,2,3 / Sd (compression) for the ROAR series :

ROAR10 - 0,73
ROAR12 - 0,67
ROAR15 - 0,64
ROAR18 - 0,65

In the ROAR designs the driver is additionally loaded by a resonator segment, and it has a double sided tapping, this combined with the rather low compression should make for decent operating conditions for the driver.

Last edited by martinsson; 2nd July 2017 at 10:19 AM.
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Old 2nd July 2017, 05:01 PM   #6
Mrscy is offline Mrscy
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Thanx, how musical does it sound in comparison to the THAM15?
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Old 2nd July 2017, 05:53 PM   #7
martinsson is offline martinsson  Sweden
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I think I'd better leave that one to Johannes seeing as he has one, I have only heard the ROAR12 one time, with a brand new driver so the T/S parameters where most likely a bit away from the spec sheet, but it still made an impression, I remember thinking that it it sounded massive, not as "light" as the THAM designs.

I'd like to hear two RORAR12 (or any of the ROAR designs) with drivers that has softened up a bit, matched with a decent top system in an out door setting before attempting to give a more detailed description.
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Old 4th July 2017, 07:55 AM   #8
Circlomanen is offline Circlomanen  Sweden
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I strongly believe in using as low compression (S1,2,3/Sd) as possible. I have seen cones buckle and crack with compression as low as S2= 0,5XSd in tapped horns and tapped pipes.

The ROAR-series is designed to treat the driver cones as gently as possible when pushing the limits with sustained high power close to the drivers maximum ratings.

The ragged response in the Hornresp-sims is the low level cold voice-coil theoretical response. The response is quite different with real life frictional losses and from thermal compression and an increase in Qes due to a hot voice coil.

ROAR is a "heavy duty" horn meant to be used with lots of power in real life events. It is not meant to simulate nice in the very theoretical world of Hornresp.

I tried to describe the general character in my first post in this thread. It is quite physical and "heavy" but with a nice "punch" in the midbass. Quite similar to the THAM15, but with more "body".

It does not change character much with increased power levels. It just keeps getting louder. There is no audible compression or noise from turbulence.

The ROAR18 should sound quite similar to the ROAR12 but louder, even more physical and powerful with 10 Hz deeper low end response.

Cheers,
Johannes
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Old 5th July 2017, 03:03 AM   #9
just a guy is offline just a guy  Canada
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Quote:
Originally Posted by Circlomanen View Post
I strongly believe in using as low compression (S1,2,3/Sd) as possible. I have seen cones buckle and crack with compression as low as S2= 0,5XSd in tapped horns and tapped pipes.
I seriously doubt that. If there was a cone failure with compression ratio of 2:1 then there was a serious problem somewhere. Either it was an absolutely terrible design or it was used without a high pass filter or there were air leaks or something along those lines. Or maybe a completely unsuitable driver was chosen, one with a very weak cone. Either way it's a problem with the design or build, not the compression ratio.

I've seen reports of up to 8:1 compression ratio used with no consequence. There is no reason whatsoever for cones to buckle under a 2:1 compression ratio in a competent design.

Quote:
The ragged response in the Hornresp-sims is the low level cold voice-coil theoretical response. The response is quite different with real life frictional losses and from thermal compression and an increase in Qes due to a hot voice coil.
Yes, as I mentioned a long time ago, the response is quite different with heavy power compression. It's much MUCH worse as any reasonable person would expect.
Bottom row left - response at small signal level
Bottom row right - roughly estimated response with heavy power compression, Re doubled

ROAR18


I didn't bother to estimate the effect of friction losses, but as any reasonable person would expect, it would make things worse, not better.

Quote:
ROAR is a "heavy duty" horn meant to be used with lots of power in real life events. It is not meant to simulate nice in the very theoretical world of Hornresp.
Well this much is clear because the simulated response is terrible. The sim itself is not even an accurate representation of the enclosure. Look at the schematic in the pic I posted. See that flared section near the end in the sim? That flared section does not exist in the actual enclosure. So not only did you not strive for decent frequency response, you didn't bother to sim the enclosure properly either. If Hornresp can't do it use Akabak, don't throw out garbage sims that don't accurately reflect the plans.

I also take GREAT exception to your wording and the implied attack on the accuracy of Hornresp. "...the very theoretical world of Hornresp ..." ?!? Give me a break. If you accurately sim what you build the sims WILL match the measurements at small signal levels. That is beyond argument at this point, there's plenty of proof. You want to slam Hornresp for being "too theoretical" and then post a garbage sim that doesn't even match the plans? This kind of behavior will not stand, I will call you out every time.

If you want to say the measurements won't match the sims when the box is pushed hard into heavy compression just say that, don't take a passive aggressive swipe implying Hornresp is "too theoretical" because it can't do something it was never meant to do.

Quote:
It does not change character much with increased power levels. It just keeps getting louder. There is no audible compression or noise from turbulence.
This is either completely untrue or you did not listen to it at the levels you indicate it was created for. EVERY speaker in the world changes character when pushed into heavy power compression. Yours is no exception as I just showed in the picture.



Everything about this is bad. Terrible frequency response, the suggestion that frequency response is somehow ok at high power (character doesn't change), the sim not matching the plans, the implied attack on Hornresp, the fact that this design is being promoted without ever having been built or measured AND with all the other problems previously noted.

You have a lot of studying to do. This was clear years ago when you came up with this concept in the Danley thread where you presented so many wildly ridiculous ideas (like an extra box segment at the mouth created out of thin air by vortexes, implying the BC horn was a tapped horn and that it had a frequency response even remotely similar to this thing). I mentioned the vast amount of problems with this design way back then, it seems you have learned anything at all since then.
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Old 5th July 2017, 06:54 AM   #10
David McBean is offline David McBean  Australia
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Quote:
Originally Posted by just a guy View Post
Bottom row right - roughly estimated response with heavy power compression, Re doubled
The Power Compression tool can also be used, rather than having to manually adjust Re.
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