taming the rising high freq response of FR drivers - diyAudio
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Old 10th May 2009, 12:57 AM   #1
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Default taming the rising high freq response of FR drivers

I was wondering if most people do anything about the rising high freq response of full range drivers, or do you live with it finding the cure worse than the problem.
Specifically I want to make open baffle speakers hopefully with as small of baffles as possible with 18 inch H frames for support.
Thanks,
Paul
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Old 10th May 2009, 01:48 AM   #2
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3 ideas............

1. sit way off axis.

2. use a 10 band equalizer.

3. buy drivers that don't rise (fe167e).



We are talking about drivers with a rising response, right ?
Similar to a fostex 206e ?

Because baffle step is a whole other topic.

Open baffles get around the baffle step problem.
But a small open baffle without massive eq using expensive drivers is a bad idea to me.

Martin J King has a neat design with dual 15 eminence and a full ranger (fostex or lowther).

here is a link to a bunch of pics.
notable is an alpair 10 OB over an h frame eminence 15" and a 103e over a 15".
http://www.quarter-wave.com/Gallery/Gallery.html

Damn that alpair 10, I want one.


Norman
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Old 10th May 2009, 11:01 AM   #3
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Many (but not all) FR units exhibit some form of rising response for a variety of reasons. For e.g. the FE206E starts to lift at about 1.2KHz. There are a few things you can do about that, several of which are noted above.

1/ Most are intended to be listened to off-axis, so that's one. Eq of some form, passive or active, in terms of a shelving filter, is another.
2/A low-mid front horn is a useful option.
3/ A very large (back) horn will attenuate the extreme highs due to the considerable load being placed on the rear of the cone, which the diaphram & motor are not strong enough to overcome. But we're talking very big horns here. Otherwise, back horns are useful only from the chosen low-frequency cutoff Fo (whatever it might be) up to the driver's mass corner frequency Fhm, and can do nothing about any rising output from the driver above this point. You don't want to be running them up higher than about, oh, 300Hz, give or take, or you'll run into problems -output lobing, imaging instability and other the attendant issues.
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Old 10th May 2009, 04:01 PM   #4
pjanda1 is offline pjanda1  United States
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Keep in mind that though the response rises on-axis, the larger fullrangers also get increasingly directional. So, if you listen a little of axis, you can achieve a relatively flat in-room balance with many of them. Rooms also tend to absorb a considerable amount of high frequency sound, depending on their furnishings, thus that on-axis rise may help balance things out.

You'll also find that folks prefer very different tonal balances. There are a bunch of traditional high end guys who like speakers with big ol' soft dome tweeters. In a highly furnished room, they'll often roll off pretty hard above 7-10K (check out Stereophile's published "in room response" graphs). Those guys tend to think of anything else as "bright".

On the other end of the spectrum, you'll find gents listening to FE206E's (10db on axis rise) in ill suited bass reflex enclosures (no bass) and praising their "detail" and "speed". It sure does sound interesting to have a giant FR rise, but I can't take it for very long.

You can assemble a fullrange driver system that has pretty much any frequency balance you want. I tend to like something that trends pretty flat. It depends on the driver, the enclosure, the room and placement.

Of course, you'll also find that many/most fullrangers have some peaks in their response that aren't simply part of a rising trend. Different folks also vary in their sensitivity to these. Some find drivers that are quite flat too smooth and boring Others are very sensitive to even small high Q (tall and narrow) peaks. But, I think this is a separate issue from your question about rising frequency response.

pj
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Old 10th May 2009, 08:55 PM   #5
Henkjan is offline Henkjan  Netherlands
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all depends on how the directivity of the driver is. for larger drivers, like the Alpair10 of the CHR70, I would choose to listen off axis, but with a FAST system I built using the small W2-800 I chose to compensate in the filter.
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Old 11th May 2009, 05:37 PM   #6
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Quote:
Originally posted by pjanda1
... listening to FE206E's (10db on axis rise)
http://www.diyaudio.com/forums/showt...17#post1824217

dave

Disclosure: they were my phase plugs. And if you get a chance to go listen to his system, take your swimsuilt, he lives across the road from the beach


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Old 11th May 2009, 05:53 PM   #7
pjanda1 is offline pjanda1  United States
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Quote:
Originally posted by planet10


http://www.diyaudio.com/forums/showt...17#post1824217

dave

Disclosure: they were my phase plugs. And if you get a chance to go listen to his system, take your swimsuilt, he lives across the road from the beach


I probably shouldn't have mentioned any specific products. I'm just trying to say that it is quite possible to achieve a relatively flat trending tonal balance with fullrange drivers. It is also possible to achieve a balance that leans one way or the other, and some folks seem to prefer it that way. Overall, I view rising HF response as more of a personal choice than a problem endemic to fullrangers, and if you find you don't like something, try something else without laying any judgement upon those who like the speaker you didn't.

Maybe others have opinions more topical for the original question?

pj
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Old 11th May 2009, 06:10 PM   #8
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Quote:
Originally posted by pjanda1
I probably shouldn't have mentioned any specific products.


Doesn't matter, it illustrated the point well enough.

Quote:
I'm just trying to say that it is quite possible to achieve a relatively flat trending tonal balance with fullrange drivers. It is also possible to achieve a balance that leans one way or the other, and some folks seem to prefer it that way. Overall, I view rising HF response as more of a personal choice than a problem endemic to fullrangers, and if you find you don't like something, try something else without laying any judgement upon those who like the speaker you didn't.
Indeed. It's certainly not a given that an FR unit will exhibit a rising response. Some do, some are flat, some are slowly rolled off in the HF etc., just like many multiway designs are. You want HF rise -a couple of years back a Rodgers design had a 24db lift starting above 12KHz, IIRC. Personally, that makes me wince; I don't like bright speakers (just my taste) but I can understand the appeal, especially for middle-aged men with poor HF hearing. Everyone has their own requirements.
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Old 12th May 2009, 05:24 AM   #9
hm is offline hm  Europe
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Hello,
after multi deletes i try it again.

"I was wondering if most people do anything about the rising high freq response of full range drivers"

make a low mid horn to rise all below 800 Hz and take a sub
below 100 Hz
here a few examples:

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
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Old 12th May 2009, 09:25 AM   #10
Piek is offline Piek  Europe
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Imho most fullrange drivers (6,5" and larger) need some kind of treatment, on open baffle it is no difference, even though you can plan wisely to counter some peaks with your baffle layout.

Rising ones:
-sit way off axis and if you have some luck you even avoid (which is not likely) the 3-7KHz harshness most of them have

"Flat" ones by spec sheet(even Fe167e):
-in 99% they need a notch or two

Everything else is imho based on imagination(which is ok, be thankful for that) or sheer luck with your design and selection of driver.

Go for filters, it wont hurt.

-Micha
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