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Open baffle or no baffle for nearfield full range monitors?
Open baffle or no baffle for nearfield full range monitors?
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Old 21st November 2015, 11:56 PM   #11
mdevelde is offline mdevelde  Netherlands
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Of all speakers I've heard (a lot, have been listening to studio monitors and "audiophile" speakers for about 20 years now), I'm left with a sense that all speakers have a box colouration of some sort. I want to get away from that. It's not as bad as crossovers, those I've really learned to hate (including well executed phase correct active crossovers).
Ports are of course especially bad. But I've had no luck either with closed boxes. For instance I've owned the Klein+Hummel O300. It is a closed box and doesn't suffer from any port colouration, but it does the opposite it actually limits the driver excursion in some way which is horrible at higher volumes. But even besides this maybe it's the speaker with the least audible box colouration I've heard but it still has it a little bit.

So I don't want crossovers / multiple drivers, I don't want a box, and I don't want a flat baffle. (oh and I also don't want headphones, mainly because of losing the head related transfer function)
I think I'm in trouble haha
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Old 22nd November 2015, 12:09 AM   #12
hitsware is offline hitsware
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> Bad MDF boxes?

O.B. phans .......... It's not phobia, it's phun !

Last edited by hitsware; 22nd November 2015 at 12:12 AM.
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Old 22nd November 2015, 01:03 AM   #13
norman bates is offline norman bates  United States
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How nearfield ?

I had a pair of tang band w3-871s on an open baffle, 6" between frames.

At 1' it was magical and had bass.
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Old 22nd November 2015, 01:45 AM   #14
mdevelde is offline mdevelde  Netherlands
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Quote:
Originally Posted by norman bates View Post
How nearfield ?

I had a pair of tang band w3-871s on an open baffle, 6" between frames.

At 1' it was magical and had bass.
I was thinking 50cm to 70cm (about 2 feet).
Ok so you listened at one foot and got bass from a 3" driver! And it was magical Good to hear!
I'm hearing too there's something very special to be found listening really nearfield to a single driver without a box. Right now using 3.3" drivers I took out of some old speakers to test my idea a bit, one of the drivers has a rotten surround so I can't listen well, and I don't even have them on a baffle just bare. And yet still I hear something very special (bit EQ by ear helped though)..

Can you give me detail on your baffle size? And did you listen often to it that close or was it intended for something else?
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Old 22nd November 2015, 03:51 AM   #15
norman bates is offline norman bates  United States
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Maybe?

Years ago I made an ambiophonic demonstrator.
3" drivers more than 8" between speaker frames.
Got moldy in garage, tossed it and sold drivers.

But I used Roger Waters "amused to death".
I didn't need the ambio barrier because that was a q-sound ( crosstalk cancellation) recording.

Since you are 2', maybe a 4" driver.
Being 1' from the drivers, the ob bassrolloff wasn't happening.

Since you are 2', I'd assume 15" from speaker frame to ob edge.

But, you will have to try it, I may be off on my assumptions.
The further back, the more the drivers will hit the opposite ears.

Try a barrier.

Only problem is it hardly a relax on the couch / chair and listen to music.
Otherwise we would have studio monitors 3' from our ears.

I think most prefer a juke box with good sound everywhere.

Last edited by norman bates; 22nd November 2015 at 03:53 AM.
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Old 22nd November 2015, 04:05 AM   #16
mdevelde is offline mdevelde  Netherlands
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Thanks for the info!

I do not want a barrier though as I think sound is supposed to hit both ears for a natural sound. Not doing this is one of the problems of headphones. Some people are adding crosstalk artificially with headphones to get more natural imaging but it still sounds very artificial compared to natural sound hitting the head and both ears.
I think there's a line there somewhere between behaving more like headphones and behaving more like speakers. I'd like to flirt with that line a little bit but stay within speaker / nearfield monitor range.

15" from speaker frame to ob edge is a lot though.. that's 38cm, if I'd use the Eikona 2 which is btw effectively a 4" (10cm effective driver diameter) which has a 15cm frame size that would make 38+15+38 = 91cm total baffle width. If I'm listening in an equal triangle this would make the baffles touch well before 61cm (2 feet).
I'll do some calculations on optimal baffle size..
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Old 22nd November 2015, 07:14 AM   #17
norman bates is offline norman bates  United States
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you'd be surprised.
The 2 speakers with a barrier, the sound is directly in front of you.
Moving speakers back to the stereo triangle made the center voice a 3' wide haze less detailed blob that also was less loud (maybe 3db).
But I see what you mean so far as how something is mixed.
You can always put both speakers on 1 baffle.

Click the image to open in full size.

You could play with how far apart you want the drivers also.
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Old 22nd November 2015, 09:51 AM   #18
mdevelde is offline mdevelde  Netherlands
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Well I see no other way than a flat baffle indeed..
I just put my little test full ranges in tubes 30cm long with 10cm diameter, open back, and while this indeed gives more low mids and bass etc, it also sounds like it is in a tube. Pleasant with some music though, it resonates and gives weight etc but in no way natural and light / quick.
I'm guessing also a tube / horn that gets wider will still impart a sonic signature. Probably only a flat baffle will not impart sonics that depart from neutral and only give a frequency related effect.

Calculated the following for baffle size and angle.
In an equal triangle setup with 65cm sides and my ears at the lines of the equal triangle gives 50cm ear driver distance, 75cm (round) baffle size where the baffles touch where the drivers are pointing directly on axis along the equal triangle line (and my ears).

So with a baffle size of 75cm I'd get a 6db/oct additional drop off starting at 34300/(75*2) = ~229Hz relative to the published frequency curve.
So at ~57Hz it would be -12db relative to the published frequency response.
Compared to the same driver at 4m distance in an infinite baffle it would still be 6db louder at 57Hz because 50cm distance is 18db louder than 4m. So driver performs relatively 6db better at 50cm with a 75cm baffle.
If the 4m away driver uses a port / transmission line system it would add about 6db at 57Hz without extra effort for the driver, but this comes at a cost of bad impulse behavior / bass quality. So I could EQ +18db at 57Hz 50cm listening distance and get perfect quality bass that is linear at the same level and stress to the driver as the ported bass at 57hz 4m listening distance.
So with a 75cm baffle I see no problem using the Eikona 2 driver this way.

But.. then I read about edge diffraction a bit more.
And it seems the edge of the baffle will cause a lot of diffraction all over the spectrum. So a round baffle isn't a good design.. In fact there doesn't seem to be a great baffle design possible without edge diffraction. I'm not just worried about the effects on frequency, but more about that this means the baffle is "audible" and doesn't disappear from the ear's "sight". Which was one of my main points to begin with, disappearing speaker.
So maybe this is not what I'm looking for.. Maybe a half sphere baffle would still be better? Maybe a closed box that is a near perfect sphere? (saw a nice ikea blendle design..) Nature seems to want either a closed sphere box or an infinite baffle / flush mounting.
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Old 18th November 2016, 04:38 PM   #19
Leonidas is offline Leonidas  Netherlands
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2 way OB , planar tweet and PAP 1075 bass , sounds great !!
I also did same bass with Fostex FE206 with very good results.

sinc. Leon
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Old 18th November 2016, 05:26 PM   #20
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by sreten View Post
Hi,

You don't understand that baffle loss throws away speaker excursion,
not just response. You have absolutely no hope of EQing it down to
50Hz if its mounted on a small baffle / no baffle, even at 0.5m.

The above response is certainly not a naked driver.
Its into half space on a very large open baffle.

Your looking at about 20dB baffle loss at 50Hz and very poor SPL.

I'd recommend a tallish, thin, well rounded box, very well built,
about 10L, fitted with a Peerless 830878 3-1/2" passive radiator,
then EQ away to your hearts content. Sealed is also possible, 5L.

rgds, sreten.
There is a way to use the drivers "naked" but with very little OB losses. How? Put them up to your ear(s)! We can thank the proximity effect for that. This is pretty well known for microphones, but applies just the same for loudspeakers.

Take a woofer, suspend it in free air a meter or two away, and give it a listen. No bass, right? But then put your ear right up to the diaphragm and then what do you hear? You hear more bass! This is the proximity effect in action. NOTE that this will only be evident with drivers that actually have a response that extends into the bass region...

Even with a modestly sized OB the response below 100Hz or so is influenced by how close you are to the baffle. When you are close to the "front" of the speaker cone the SPL from it will be louder than the "rear" SPL because the pathlengths are appreciably different. This causes front SPL >> rear SPL, meaning there is not as much front-to-back cancellation compared to when you are farther away and the pathlengths are relatively similar. What you hear is trending towards infinite baffle (closed box) response.

You can hang the drivers so that they are positioned just to either side of your head/ears and you will be getting the on-axis, near-infinite-baffle response beamed right in there, not to mention you will only need very little amplifier power to drive them. It's won't look very pretty, but you will be in the nearfield and the room response (including room resonances) will be imperceptible and you will have practically no "baffle step" or "open baffle" losses. The sound will be similar to when using headphones, however, and some of the benefits of the open-baffle loudspeaker's room interaction will be lost.

Keep in mind this will not "augment" the bass. For a full ranger driver the infinite baffle bass output is typically rather anemic. But because your ear(s) are very close to the driver(s) their SPL output level will be much lower, meaning you can boost the low end more for the same overall excursion (compared to a typical listening distance of 2m). This is why a tiny headphone driver can still reproduce bass - it's right at your ear.

This would be a nearfield speaker in the truest sense of the word.
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