[this_is_vv]

Hi Jimbones ~

From time to time Deborah and I go to audio shops to listen to
this or that highly rated box speakers... just for the fun of it...
and to see if our 'listening' ear has changed. One's listening...
one's sense of the "real" in reproduced music does change over
time and this is one way to get a sort of reality check (another
way to is to change amps... which I have done recently and which
has indeed changed my listening habits for me... I intend to write
about that soon). Deborah is not particularly interested in audio as
a technology... as long as the music has something of that ineffable
quality of being able to take flight and involve us emotionally,
she is very happy.

It is the music that Deb loves. So when we visit audio shops I am
very keen to find out what she thinks. Ever since we began to listen
to our Open Baffle Speakers, about 7 years ago, Deb's perception
immediately hears the constrained 'boxy' non-musical sound of
boxed-speakers. She does not like them.

What I have found is that if one has patience and is willing to work
with the Open Baffle paradigm... which means voicing them to
your taste... you can get them to sound quite wonderful. No
commercial speakers I have ever heard... and I have heard
hundreds of 'commercial' speakers, including the top rated audio
celebrities with gushing superlatives dripping from the pens of
enamored audio scribes... can come close to my Open Baffles
for bringing the music to life... detail, holographic spatial cues,
immediacy, the penetration of the 'air' of the room which
simulates a live performance of un-amplified music, depth
of tone, texture and so on.

What happened to me is that after working in the Open Baffle
paradigm for a while, I began to 'hear' what commercial
speakers actually sound like... and they all sounded/sound
limited in some essential way... especially in the sense of
sounding flat and directional. It is the difference between
hearing a newly built musical instrument compared to one
that was built centuries ago... the older instruments have
that special resonance that gives another dimension to the
music played on them... Open Baffle speakers sound like
that to Deb and I.

Also my experience regarding the question of needing space
behind Open Baffle speakers seems to be different from
many of our Audio Circle friends. I live in a manufactured
home, my simple Open Baffle panels are around 3 feet from
the front wall of our home which is mostly glass and a hard
thin surface material. There is an accordion-style window
shade that covers about half the windows on the bottom at
all times. In other words, my home reflects what is normally
considered a poor surface for the back wave to have to
contend with. But the music is quite wonderful... sometimes
I even pull the speaker panels closer than 3 feet... to 2 feet
from the front wall... and the sound is still quite acceptable.

I suspect that the reflection of the back wave from the hard
surface of the wall to the front may be helped by the hard
surface. There is a rug on the floor that the speaker panels
rest on... and that may help to keep both the front and back
wave from traveling with too much energy. I am not saying
that some form of intelligent acoustic treatment would not
further refine the sound... it very well could. I am only
suggesting that perhaps working simply, even with the
limitations of what one has, may be enough to have a
very satisfying musical experience with one's Open
Baffle speakers.

Thanks for sharing your experiences with us... please
continue to share your insights with us.

With Warmest Regards ~ Richard / Ojai, California

there never goes a time i dont read your post regarding Open baffle....its amazing...i jsut finished an OB for PC speaker and result for my ears are nothing less then stunning...

V

[jimbones]

Ojai!? Thats where my favorite performer lives. Dave Mason. I guess you're neighbors.
Can you tell us about your build/system? Is there a link to it? I would love to know what drivers you have used with such good results.

Best,
JIm

[-Richard-]

Hi jimbones ~

My current system uses an 8" wide-range driver, the Dayton Audio PS220-8 8" Point Source Full-Range Neo driver (quite a mouthful) crossed over with the 15" Eminence Alpha 15A, using a simple coil inductor to cut the Eminence off at around 250 Hz. The 'design' is a simple flat panel. Here is an earlier picture using the Visaton 8" on top (now replaced by the Dayton):





It is helpful to read the thread: http://www.audiocircle.com/index.php?topic=107397.0
Scorpion/Erling tames my Dayton 8" wide-range drivers with a BSC, in the Open Baffle forum, to see how Erling's recommended BSC, and his newest thinking about an even better suggestion for a BSC in conjunction with a notch-filter, can modify the Dayton driver in order to tame their otherwise "hot" upper frequency response.

I don't think my Open Baffles are especially unique in any way. I think the Open Baffle paradigm is what is at work here... and a good synergy with a sympathetic amplifier.

When I purchased the Dayton drivers I thought now here is cheap (less than $100 each) driver that looks like an expensive English full-range driver... let's give it a try: http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-346

The upper frequency rise is not uncommon in 8" wide-range drivers... but admittedly, if I did not have an amplifier with tone controls (no longer necessary) it would have been difficult to take. Erling read a positive review of the Dayton's in a well-regarded German audio magazine in which the reviewer had a positive response... and was intrigued enough to 'model' the Dayton's frequency response using software that allowed him to suggest a BSC filter for it. When I applied Erling's filter suggestion the Dayton became a giant killer. Compared to the Visaton 8" B200 driver, the Dayton is much more detailed, has greater frequency extension and is more focused.

Still, there are probably much better 8" drivers out there that are close to the Dayton's price range... perhaps much smoother, warmer and with a flatter all-over frequency response without the need for a filter in the circuit. The use of a filter could affect the efficiency of the Dayton's making them less low-watt amplifier friendly, if one's amp generates only 2 or 3 watts. My 7 watt Triode push-pull EL 84 amp easily drives them.

But I feel no need to upgrade to another 8" driver at the moment... with the new Class D amplifier I am now using, with a simple tube preamplifier, what I am hearing is quite extraordinary... pure music that pours from this system... with a focus and separation of voices and instruments and with a textural depth and definition I previously thought impossible to achieve with the Open Baffle design approach. I am waiting for an upgrade to this cheap amplifier before writing about it... it is due to arrive back in a few days.

With Warmest Regards ~ Richard / Ojai, California

[Redefy Audio]

if i may suggest, eminence beta15a is better performer. the alpha is too muddy.

[ebag4]

if i may suggest, eminence beta15a is better performer. the alpha is too muddy.

Interesting, that is at least the second time I have read that.  The QTS number for the Beta is less than half that of the Alpha so I would have assumed the opposite to be true, but you mentioned the Alpha being too muddy as compared to the Beta, perhaps the Alpha's QTS is too much of a good thing.  The .58 QTS for the Beta would appear to be a bit low for OB, at least at first glance.

Best,
Ed

[Rudolf]

if i may suggest, eminence beta15a is better performer. the alpha is too muddy.

And you found that with both drivers EQed to the same (or at least almost same) frequency response in your room? If you simply changed one driver for the other, the beta15a would be bass shy of course.

Rudolf

[scorpion]

I think Alpha15 bass superiority is a bit of a myth.

Alpha15 has Fs = 41 Hz and Qts = 1.26 and Beta15 has Fs = 35 and Qts = 0.58. Mostly (in OB) you have to cross from bass to midrange about 200-300 Hz were in fact you will cover a lot of instrumental and voice fundamental tones in the bassrange. I have no experience with the Beta15 but henry218  here and others state that they are better than the Alphas. I have compared Alphas to AE IB15 and A&D R1524
both of which are clearly sonically better than the Alpha15 in my judgement.

Simulation of the units on a 40 x 20 " baffle, two of them placed 8" and 23" up from floor.

Alphas first, crossed at 200 Hz 2nd order L-R:





Betas, crossed at 160 Hz, to give the same SPL level as the Alphas, 2nd order L-R:



So what is the main difference. The Betas may be about 3 dB down compared to the Alpha at 40-50 Hz in all other frequencis they will be more or less equal.
This is the trade-off then, some dBs in the very low bass instead of overall clarity and articulation.

/Erling

[MJK]

This is the trade-off then, some dBs in the very low bass instead of overall clarity and articulation.

Erling,

Not much argument with the difference in dB of the low bass, it can be seen easily in the plots. But the second statement of better clarity and articulation is really an opinion. There are people on both sides of this argument, some say the Alpha 15A is muddy but many others love it and swear by the bass performance. It would seem to be a matter of personal taste and maybe somewhat amp and room dependent.

Martin

[scorpion]

Hi Martin,

Yes, I mostly agree, I think both positions as usually stated are subjective - a statement of what a person says he/she is hearing.

The difference can be just between the speakers as such. In addition to factors you mention as causing difference I could also see the listeners experience of music and how
instruments actually sound to be a ground for individual taste.

/Erling

[ricardojoa]

Hi,
I really want to experience an OB speaker, but im not really sure my room is suitable, infact i think is not. My room is actually quiet small and i only have about a foot for the speaker for behind wall. Would i be better off with a closed box or are there anything i can do for OB speaker such acoustic panel behing speaker?

[fsimms]

I have Salk SoundScape 10s.  They can be run in an open baffle mode or in a closed box mode.  When run in the open baffle mode they have a wonderful natural bloom that makes music much more enjoyable.  That same bloom makes voices less clear so it is a slight disadvantage to listening to TV and movies.  I fix that problem by closing the back of the speaker.  I would guess you could also fix that clarity problem by using a closed box center channel that matched the voicing of your open baffles.

An other difference is that the open baffles bounce sound off of the front wall behind the speakers.  This means that the acoustics of the wall may affect the sound.  This is usually fixed by moving the open baffle speakers into the room by at least 4 feet.   I have mine closer than that so I have an absorber/diffuser panel behind my speakers to manage the reflected sounds.

Open baffle speakers have a larger than life image.  My SoundScapes have wings or walls around the open baffle midrange that form an open backed box.  This box makes the image more normal sized, so I don’t have that effect.

I can stuff the midrange open backed box with poly-fil to reduce the open baffle effect, so some of the issues mentioned above might be slightly different with a fully open baffle speaker.

The SoundScapes are hybrid open baffles and have a closed box base module, so I can’t speak to bass issues.

Even mono recordings sound full and lively in the open baffle mode.

Bob

PS Richardoja,

The above absorber/diffuser panel works very well for me with my speakers close to the wall.  See pictures in my Gallery.

[LiveSound]

Typical cone/box speakers sound boxy.  Much of the expense is trying to minimize the interior standing waves that contribute to the boxy sound and the cost of making the boxes "pretty furniture".

All too often, IMO, more of the cost of box speakers goes to address these two parameters than the quality of the drivers and crossovers.

Since the late 90's I have used Gallo Nucleus Solo's.  Spun aluminum spheres, 6.5" main driver and a proprietary "capacitive" tweeter.  No crossover. No box sound.  To me, the best of both worlds, panel speaker openness with pinpoint imaging and the dynamics with which planars struggle.

I have often been very impressed with the realistic and relaxed sound of OB's.  I have been working on a design of an OB for efficiency.  (I am just finishing 300B SET monoblocks @ about 7 watts per side).  The design is a variation of Martin J. King's published OB study project using  8" Audio Nirvana cast drivers and Eminence Alpha 15 woofers.  I am bi-amping with tubes.  I am at the end of several months of crossover listening and almost ready to go to my finished baffles. The short take.  I am really happy with the sound of the OB's, even in their "mule" baffle stage.

I listen to mostly acoustic music, female vocals, jazz and classical.  The sound of these OB's is simply compelling.  They don't have quite the detail of the Gallo's, but I need much more power to run the Gallos. (GTA monoblocked SE40's or Rogue Magnum 150's)

So, after this long post, I think that speaker choice needs to be a combination of household acceptance factor, amplification and musical tastes.

Cheers,
Geary

Hi Geary, 8 years on, how are you getting along with the set up, an interim report and maybe some pictures would be great, I am on a similar track as you! Jean

[bladesmith]

The only advantages I see in box speakers is cosmetics and in many cases a smaller footprint.

I agree in most cases yes..generally speaking ofc..

 

[Zuman]

What a wonderful discussion! A few decades ago - before marriage and children - I started to build a 2-channel system around a pair of the original Martin Logan CLS electrostatics. I'd never heard (or seen) anything like them before, and I was transfixed by the pristine, crystalline sound the CLS speakers produced. Of course, they required compromises in terms of my music library, my seating position, my ancillary electronics, and my room.
After a few years, my priorities shifted and reproduced music became a smaller part of my life. I still enjoyed it tremendously, but I also enjoyed a wider range of  life's other aspects, and the reality of being a married father with a job, a finite paycheck with legitimate demands on it, and a shared domestic environment based upon harmony of a different sort required me to adapt, and my audio system became smaller, simpler, and less "invasive." And you know what? I didn't resent it.
Now I'm newly-retired and my children have grown and left the home, and my system has evolved further. I use a NAD M50.2 digital vault/player and a modified Rega table feeding a NAD M32 digital integrated amp, outputting to a pair of CSS Criton 2td-x home-built MTM speakers, which sit less than a foot from the wall behind them. I still listen to live music outside of the home, and I still know what good reproduction sounds like, and I'm happy with what I have in my balanced life.
My only advice is to carefully consider whether you are on a relentless hunt for perfection or, instead, for a sweet spot in your life. Then learn from the wisdom in this and other threads and make your move. But don't paint yourself into a corner, and don't be afraid to change your course.

[planet10]

That being said, they really don't do anything wrong.

Not true. First every loudspeaker has. zillion compromises.

But every OB i have built or heard has the same issue which tends to be quite distracting to me.

Many of the arguments for OBs are from those that don’t understand what is happening.

Many people are very happy with OBs, not me.

Most boxed speakers have significant issues as well, but i have tailored those to get (mostly) out od the way (for my listening).

As a generalization, an OB needs some significant room (the best ones i heard were outside and some 14 feet from the wall behind). It needs to have significantly more woofer than other loudspeakers as the design throws away bass, particularily narrow baffle ones.

The bass can be a problem or an asset depending on your room, they have a quite different polar response at the bottom than a boxed loudspeaker.

dave

[planet10]

Cone drivers release a + acoustic wave to front and a - acoustics wave to back, when these sound waves meet there is a loss of 4 to 5dB in comparison to a boxed driver.

Below the baffle cutoff the bass falls off at 6dB/octave.  The narrower the baffle the higher up in frequeny tis occurs.

This is compensated for with either a filter or a high Q woofer. The filter is an agressive one that throws away sensitivity for extension. This is why you often see 1 or more 15 or 18” bass drivers. Much of their capability is being tossed out.

dave

[planet10]

Typical cone/box speakers sound boxy.

Becuase most are poorly built, at least commercial loudspeakers. Lots of ¾” MDF crappy carcasses for one.

If you don’t get the box out of the way you will hear it.

dave

[planet10]

...obviously all baffles have a bottom, its called the floor.

Not all. These worked really well in the big shop for background music.



dave

[planet10]

-Open baffle has a more tube like, airy, soundstage and presentation. Boxed speakers are more like solid state amps.

False.

-Open baffle has no box coloration. Good boxed speakers greatly reduce this and can be very enjoyable indeed.

False. But as said, there are lots of bad box speakers to put up as examples.

-Open baffle is a lot easier for DIY builds, construction wise. 

Typiclly less, but often moire filters and electronics/

Open baffle speakers need lots of space behind them, or good dampening on the rear wall, behind the speakers. For that matter, all speakers benefit from space from walls for soundstage realism.

Certainly they tend to need a big room.

dave

[planet10]

...immediately hears the constrained 'boxy' non-musical sound of boxed-speakers.

One of the “boxiest” speakers i ever heard was an OB.

So you can toss that absolute.

dave