• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

"Monkey Coffins" (box speakers) and Resonances...

OP
D

dlaloum

Major Contributor
Joined
Oct 4, 2021
Messages
3,092
Likes
2,353
42cm wide apparently - that is much wider than most mainstream speakers. The Grimm LS1 is 52cm wide and that's a design explicitly based around using a wide baffle for directivity control.
Yes but - it you look at the image, there are angled corners, so the front baffle is narrower than the full width...

Effectively the baffle width is the width of the 8" woofer + the port.... I compare that to the A400 - the baffle is 3 times the width of the woofers

Sure it isn't what I would call a "narrow" speaker - as is now the fashion (where typically the width of the speaker is often the width of the midrange driver, or thereabouts... - but it is by no means a wide speaker...

It would be interesting to know what the "baffle step" frequency difference is between a wide speaker like the A400 and what I would call a "standard" width box speaker like the Agora B, and then compared to a current generation "Narrow" speaker eg: Keff R-7 - where the width is driven by the 6.5" woofers...

Boston A400 Baffle W= 21" / 53.3cm
Revox AgoraB Baffle (est) W = 14.2" / 36cm
Kef R7 W= 7.9" / 20cm

P.S.: I have no idea whether the Kef R7 has the "box sound" or not..., and I have no idea where one draws the line between a "wide baffle" / infinite baffle design, a "normal" design, and a "narrow" baffle design... - The A400 is clearly "wide" - but the others?
 
Last edited:

polmuaddib

Senior Member
Forum Donor
Joined
Mar 1, 2020
Messages
479
Likes
852
How about a different approach in identifying "boxy" speaker sound?
Between loudspeakers measured by Amir here and Erin and some at Soundstage (unofrtunately, Stereophile measurements are very low resolution IMO) can you find that resonance you suspect exists?
Most of those speakers are true box speakers. Some have resonances in the sensitive range between 1 khz and 3 khz, but very few. And those that have resonances are not always cabinet sourced.
If you could identify the speaker brand and model that you hear sounds like monkey coffin and their meausrement is available, then if there is a resonance, it will show on the frequency response.
 

mcdn

Addicted to Fun and Learning
Forum Donor
Joined
Mar 7, 2020
Messages
559
Likes
780
Yes but - it you look at the image, there are angled corners, so the front baffle is narrower than the full width...
52cm is the full width including the rounded edges of the Grimm LS1 so the comparison is totally fair. the baffle step (I.e. transition to omnidirectional radiation) of the Revox will be much lower than most mainstream loudspeakers.
 
OP
D

dlaloum

Major Contributor
Joined
Oct 4, 2021
Messages
3,092
Likes
2,353
How about a different approach in identifying "boxy" speaker sound?
Between loudspeakers measured by Amir here and Erin and some at Soundstage (unofrtunately, Stereophile measurements are very low resolution IMO) can you find that resonance you suspect exists?
Most of those speakers are true box speakers. Some have resonances in the sensitive range between 1 khz and 3 khz, but very few. And those that have resonances are not always cabinet sourced.
If you could identify the speaker brand and model that you hear sounds like monkey coffin and their meausrement is available, then if there is a resonance, it will show on the frequency response.

If only I knew what I was looking for!

As in any scientific endeavour, you collate data, and look for correlations... but the data collected from Amir's measurements would need to be cross indexed with the responses of various listeners sensitive to "boxyness" ... typically people who have had panel speakers for years.

Yes we have the measurements, but we do not have the related table (or perhaps just a checkbox) - saying Boxyness yes/no - and without that, there is not much that can be done with the measurement data.
 
OP
D

dlaloum

Major Contributor
Joined
Oct 4, 2021
Messages
3,092
Likes
2,353
52cm is the full width including the rounded edges of the Grimm LS1 so the comparison is totally fair. the baffle step (I.e. transition to omnidirectional radiation) of the Revox will be much lower than most mainstream loudspeakers.

"mainstream speakers" - at the time, I would have called a Boston A100, a mainstream speaker - definitely wide baffle...
A Yamaha NS1000 is probably a wide baffle too.... it was a "mainstream speaker" - and it's competitors from various other brands Marantz, Pioneer, etc... at the time they were all mostly in the 40cm to 50cm widths.

Our ideas of "mainstream" may be slightly divergent... mine is rooted in the last 45 years....

And given I have not done much audio-show listening in the last 7 or 8 years.... it well may be that the boxyness I mention, has become far less common than it once was- I have no idea!
 
Last edited:

Dumdum

Senior Member
Joined
Dec 13, 2019
Messages
338
Likes
219
Location
Nottinghamshire, UK
That is free-air radiation, not captured radiation. No pressure wave causes structural resonance there.



In order to prevent the concrete from cracking (he definitely didn't want to do this over again!) the walls were about 35mm thick. Believe me, they were not going to move or vibrate.



This reminds me of some of the old cabinets that were sand-loaded or lined with lead sedum or lead sheets. Some (not all) of those worked rather well. Jim
Concrete is awful for speaker cabinets, go to a foreign hotel constructed on concrete and listen to someone running around upstairs and then tell me it doesn’t ‘ring’ or transfer sound when excited
 

Mart68

Major Contributor
Forum Donor
Joined
Mar 22, 2021
Messages
2,609
Likes
4,860
Location
England
Concrete is awful for speaker cabinets, go to a foreign hotel constructed on concrete and listen to someone running around upstairs and then tell me it doesn’t ‘ring’ or transfer sound when excited
have you had a listen to any concrete loudspeakers? It does actually work very well, there's no ringing. They're just a bastard to move around even if they are small.
 

mcdn

Addicted to Fun and Learning
Forum Donor
Joined
Mar 7, 2020
Messages
559
Likes
780
"mainstream speakers" - at the time, I would have called a Boston A100, a mainstream speaker - definitely wide baffle...
A Yamaha NS1000 is probably a wide baffle too.... it was a "mainstream speaker" - and it's competitors from various other brands Marantz, Pioneer, etc... at the time they were all mostly in the 40cm to 50cm widths.

True, wide baffles were more commonplace in the 1970s through the mid '80s. I was about to ask for some examples of speakers you thought sounded "boxy". Is the Yamaha NS1000 one of them?
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
3,722
Likes
6,405
So, I became an audiophile in my late teens, and at 20 was working in a "HiFi" store (also the first home theatre store in our region!) ... circa 1985.

We had Quad ESL-63 electrostatics, Revox Agora B active, Boston Acoustics (A40 through to A400), also Pioneer, Marantz, and Magnat.

That might lead to - how does one eliminate the boxy sound if a speaker has it?

In the '60s through mid '70s there were (roughly speaking, and lumping a lot together) basically three types or sounds of loudspeakers. I'm talking average 'consumer' stuff. Gear you'd actually find in your local hi-fi stores. There were:

1) AR type acoustic suspension sound, which was generally considered more accurate, tonally, but suffered from a very 'closed in' boxy presentation that many (including me) considered pretty lifeless. Those who didn't like it weren't usually offended by it, however. They just didn't sound 'life-like' for them. They also required more amplifier power than not, and watts were not cheap, back then.

2) JBL reflex sound was generally considered inaccurate, tonally, but didn't have the marked closed-in boxy sound associated with acoustic suspension designs. Instead, you got a more 'forward' and 'out of the box' type of sound. Reactions were mixed and polarized--either listeners liked it, or hated it. I think it is accurate to say that period JBL's 'offended' the sensibilities of the more 'refined' listener. I tended to like it, simply because it wasn't 'boxy'.

There was also the 'theater' sound. Horns. They didn't sound boxy, but were expensive, and not very practical within a smaller domestic environment.

Quad (original ESL) was an outlier, and seldom seen or heard in the US. It was certainly anti-box, but had its own limitations. Limitations that to many were considered disqualifying.

The first 'mass market' design that attempted to get 'outside the box' was probably the Bose 901. It was sort of the Phil Spector of loudspeakers... a 'wall of sound' that sounded pretty... well, regardless of what anyone thought about it, it certainly didn't sound like music coming from the front of a sealed box. So it had that going for it.

At the 'high-end' (it wasn't really that expensive, actually), the Jon Dahlquist/Saul Marantz DQ-10 was an attempt to get around the box. It had it's own peculiarities, but didn't really sound boxy. Another 'popular' idea was Lincoln Walsh's omin invention, sold by Ohm.

Those are the one's I remember, from early on. Later, the most inexpensive and likely most successful implementations of anti-box design were Jim Strickland's Acoustat (electrostatics), and Magneplanars. The latter are still in business, showing that, like Klipsch heritage large horns, there remains a certain appeal for this kind of thing.
 

fineMen

Major Contributor
Joined
Oct 31, 2021
Messages
1,504
Likes
679
... - how does one eliminate the boxy sound if a speaker has it?

(or is it so fundamental to the design, that it is best to move to a different speaker... as I did)

Problem is to understand the problem. What is the problem? You tell there is a solution, before the problem is stated.

You say, there is s discernable quality to boxed speakers versus others, but I cannot agree less. I never felt there was boxy sound with boxed speakers. More so, those unboxed often sounded boxy to me.

Do You have anything an engineer could get hands on? If You are satisfied, as an individual consumer, with alternative non-boxed speakers, why don't You settle and let it be? Why do You call boxed speakers boxed, or 'monkey coffins', if it wasn't for the looks? The nutshell, would You mind to explain to me what a 'resonance' may be? I'm curious if Your terminology would align with my educated guess.
 
OP
D

dlaloum

Major Contributor
Joined
Oct 4, 2021
Messages
3,092
Likes
2,353
I gave a particular sound signature a name, reflecting my experience... "boxy sound" - do all box speakers have it - no, do any non box speakers have it, no...

I deduce based on my personal experience that this is a phenomenon limited to "box speakers" - hence the name I allocated it.

I also identified that I had not heard that signature sound from smaller box speakers aka "bookshelves" - but that my experience of it, was exclusively from floorstanding speakers.

The other identifier which may or may not be of relevance, was that the speakers I heard it in were usually, what people today would call "wide baffle" - although in the 80's and 90's most of those speakers would not have been considered wide enough to be "wide"... but norms/averages shift. - And it is also possible that narrow long speakers suffer this problem less (whether the long side is to the fron, or whether it is to the side - like the Boston A400) - so there is a likelihood that the problem manifests more frequently in speakers of a certain volume where the horizontal cross section is closer to a square.

All I have are data points - an engineer works on known principles.... a scientists looks at various data points, seeks to identify a common thread, correlations, from which to develop a hypothesis... cause and effect relationship, from which he/she then develops experiments to test it, and based on that produces a principle.... on which an engineer can then work.

I did not at any stage claim to have the known principles on which to pin this - and on which an engineer could then pin a design - just a bunch of data points, and an observation on a particular sound signature that some people (me included) are sensitive to.

If I could understand that signature better, it would open up my options whenever shopping for speakers! - There is no way of auditioning a decent cross section of the market - and reviews, where one does not know whether the reviewer is sensitive to this same signature or not, are not much use! (Reviewers with a liking for and history with panel speakers, are likely to be sensitive to it.... and therefore more trusted than others).

The problem is clearly stated - when present, I hear it. The next step, identifying in a quantifiable, measurable way, what exactly that audible signature is, that is the gap.
 
OP
D

dlaloum

Major Contributor
Joined
Oct 4, 2021
Messages
3,092
Likes
2,353
In the '60s through mid '70s there were (roughly speaking, and lumping a lot together) basically three types or sounds of loudspeakers. I'm talking average 'consumer' stuff. Gear you'd actually find in your local hi-fi stores. There were:

1) AR type acoustic suspension sound, which was generally considered more accurate, tonally, but suffered from a very 'closed in' boxy presentation that many (including me) considered pretty lifeless. Those who didn't like it weren't usually offended by it, however. They just didn't sound 'life-like' for them. They also required more amplifier power than not, and watts were not cheap, back then.

2) JBL reflex sound was generally considered inaccurate, tonally, but didn't have the marked closed-in boxy sound associated with acoustic suspension designs. Instead, you got a more 'forward' and 'out of the box' type of sound. Reactions were mixed and polarized--either listeners liked it, or hated it. I think it is accurate to say that period JBL's 'offended' the sensibilities of the more 'refined' listener. I tended to like it, simply because it wasn't 'boxy'.

There was also the 'theater' sound. Horns. They didn't sound boxy, but were expensive, and not very practical within a smaller domestic environment.

Quad (original ESL) was an outlier, and seldom seen or heard in the US. It was certainly anti-box, but had its own limitations. Limitations that to many were considered disqualifying.

The first 'mass market' design that attempted to get 'outside the box' was probably the Bose 901. It was sort of the Phil Spector of loudspeakers... a 'wall of sound' that sounded pretty... well, regardless of what anyone thought about it, it certainly didn't sound like music coming from the front of a sealed box. So it had that going for it.

At the 'high-end' (it wasn't really that expensive, actually), the Jon Dahlquist/Saul Marantz DQ-10 was an attempt to get around the box. It had it's own peculiarities, but didn't really sound boxy. Another 'popular' idea was Lincoln Walsh's omin invention, sold by Ohm.

Those are the one's I remember, from early on. Later, the most inexpensive and likely most successful implementations of anti-box design were Jim Strickland's Acoustat (electrostatics), and Magneplanars. The latter are still in business, showing that, like Klipsch heritage large horns, there remains a certain appeal for this kind of thing.

You missed one obvious North American brand in this area - Martin Logan... I spent quite a bit of time listening to their full range ESL - the CLS... and far preferred its tonal rendition, to their hybrid designs... which seemed to me to not quite get the mid-bass right.

I believe the Quad ESL-63 did quite well in the US... although the earlier original ESL (now usually called the ESL57) seems to have been rare.
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
3,722
Likes
6,405
You missed one obvious North American brand in this area - Martin Logan... I spent quite a bit of time listening to their full range ESL - the CLS... and far preferred its tonal rendition, to their hybrid designs... which seemed to me to not quite get the mid-bass right.

I believe the Quad ESL-63 did quite well in the US... although the earlier original ESL (now usually called the ESL57) seems to have been rare.
I was thinking more along the lines of the more popular brands from the '50s, '60s and '70s. Martin Logan, I believe, came later. At least I first heard about them later in life. Certainly the original Quad didn't have adequate US distribution. The earliest I recall was Bud Fried, who ran a hi-fi store in Philadelphia. He imported Quad, selling through his storefront. Fried ran some ads in Audio magazine, but most of his sales were likely word of mouth, and New England regional, I'd suppose.

There were other ideas in this regard--Bose was not the first to use the direct/reflected sound in order to create a less boxy sonic image. But he was the first to really market the idea on a large scale. I think that is the reason his speakers were so successful. Not that they sounded anything like live music, but because they didn't sound like anything anyone had ever heard coming from a small box. Their sound was all over the place... for better or worse.

KLH produced their Model Nine electrostatic. Dayton-Wright was another electrostatic with limited distribution. Stax panels. Those three brands had a very limited 'cult' type following, and none could ever be said to sound like a box loudspeaker. Bass response was usually their downfall.

Before those, Janszen marketed an add-on electrostatic module that was often used with AR type acoustic suspension speakers--in order to give them some 'life' in the upper registers. In fact, the Janszen design was essentially the KLH Nine, using a three panel 'room divider' form factor that would make a later appearance with the early Magneplanars, distributed by ARC. Acoustech (not Acoustat) was also associated with Janszen (and Henry Kloss, after leaving KLH). Arnie Nudell's Infinity Servo-Statik, and, later, Harold Beveridge's loudspeaker all come to mind as outliers in their own right. ESS AMT was also from the mid '70s.

There are probably a lot more that could be mentioned, but the above are some of the better known anti-box designs.
 

dfuller

Major Contributor
Joined
Apr 26, 2020
Messages
3,335
Likes
5,050
1) AR type acoustic suspension sound, which was generally considered more accurate, tonally, but suffered from a very 'closed in' boxy presentation that many (including me) considered pretty lifeless. Those who didn't like it weren't usually offended by it, however. They just didn't sound 'life-like' for them. They also required more amplifier power than not, and watts were not cheap, back then.
So low sensitivity, mediocre dynamic range capability, etc at the benefit of linearity.
2) JBL reflex sound was generally considered inaccurate, tonally, but didn't have the marked closed-in boxy sound associated with acoustic suspension designs. Instead, you got a more 'forward' and 'out of the box' type of sound. Reactions were mixed and polarized--either listeners liked it, or hated it. I think it is accurate to say that period JBL's 'offended' the sensibilities of the more 'refined' listener. I tended to like it, simply because it wasn't 'boxy'.
So high sensitivity/good dynamic range capability, but poor linearity.

IIRC, this is what ATC's initial founding ideal was: dynamic range/sensitivity of #2, but linearity of #1.
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
3,722
Likes
6,405
I know I paint with broad brushes, however my experience is that 'once a box, always a box'. What you get are gradations within the genre. For example, the JBL L100 sounds nothing like the AR3a, however in spite of the former's radical (by comparison) sonic contrast with the latter, you can still 'hear' the box in both, albeit from a different angle, as it were.

I admit to not living with the latest and greatest two-way Klippelized wunderkinds, but it would surprise me if even the best of those do not have a recognizable box-like signature. I am happy to be proven wrong, but in my current situation I doubt I will ever have the opportunity to experiment further, in this regard.

Pure electrostatics have none of that, but once you familiarize yourself with electrostatic sonic properties, you start to hear their intrinsic characteristic, and inherent limitations, in spite of their un-boxiness.

Of course I'm talking about readily available and relatively affordable 'consumer' items. DIY designs like the Linkwitz open baffle could be an important option, but let's face it, his LX-521 isn't a trivial DIY project for the guy who just wants to 'unbox' something (nice play on words, eh?). Next? There's the B&O monstrosity, which is said to overcome a lot of traditional loudspeaker limitations..., for a price (and if you don't mind overall weirdness in design). Some very expensive variations on the Walsh driver are out there. And so on.

I find that it just comes down to whatever tradeoffs one wants to put up with. Once you establish that rather fixed parameter, then any sound variation you get will be primarily from the type of recording you put on your record player, or CD player, or streamer. That is to say, the decisions the producer/engineers made when putting the recording together are going to be determinant.

Obviously one's listening room is important in the overall mix, but few adapt their listening room to their loudspeakers. Usually it is the other way around.
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
3,722
Likes
6,405
PS: although later than those historical loudspeakers I mentioned, I'd like to highlight another design I had the pleasure to spend some time with. The Infinity Beta. Using the company's proprietary EMIT/EMIM drivers in an open baffle high/mid design, it was decidedly unboxy in sound. And came with rather attractive feng shui, IMO. FWIW it was the best Infinity speaker I ever encountered.

The operation began as a tweako company with some 'interesting' ideas. Some good, some questionable. Their first splash was a Janztsen-esque design, the Servo Statik. But they were committed to their often iconoclastic version of 'high-end' sound..., one not always appreciated by the press/marketplace.

Harman bought the company and let the brand flounder. Last I heard they were slumming the dregs of the aftermarket car speaker business.


1205irsbeta.jpg

by
 

Pete Basel

Member
Joined
Jan 3, 2022
Messages
32
Likes
34
My personal experience:
I remember listening to AR and the Large Advent speakers back when they were popular
and wondering where that "boxy" quality was coming from. Was it characteristic of
sealed box or something else?
Years later I learned that it was the lack of or insufficient baffle step compensation in the
crossover network. The frequency response was wrong for the typical home listening room.

I never bought the story that it was some sort of in box, or box wall resonance.

It is easy to experiment with this through a miniDSP or various other forms of EQ.
 
Last edited:

ferrellms

Active Member
Joined
Mar 24, 2019
Messages
296
Likes
254
So, I became an audiophile in my late teens, and at 20 was working in a "HiFi" store (also the first home theatre store in our region!) ... circa 1985.

This retailer sold speakers that have affected my audio journey ever since...

We had Quad ESL-63 electrostatics, Revox Agora B active, Boston Acoustics (A40 through to A400), also Pioneer, Marantz, and Magnat.

I also spent some time getting to know our competitors, visiting them chatting with them listening to their speakers....

The speakers I had a huge preference for, were the Electrostatics ... Quad ESL-63, and its competitor down the road... Martin Logan CLS, I also loved the Boston A400's. - The Revox Agora B was nice.... but the others were better.... the Pioneer, Marantz speakers all were middle of the road "boxes", and I disliked the Magnats, finding their Metal dome tweeters harsh.

I heard many speakers then, and in subsequent years (when my career took me into IT rather than audio) continued listening to a wide range of speakers....

Typically I can tell a "Monkey Coffin" (AKA Box Speaker) - almost instantly - there is a distinctive "sound" to them - I believe this is caused by resonance of the speaker walls (some peope have reported a common resonance around 1.5khz for many speakers.... this may be what I have been noticing).

This was (and is!) totally absent on Electrostatics, and other panel speakers - I have also found it to be absent on "Orb" speakers - and some other "funky shape" designs... including my current Gallo Nucleus Reference 3.2's.

Another observation from long term listening, is that smaller bookshelf speakers, tend to suffer markedly less from this "box" sound than do large floorstanders... perhaps a simple property of the larger surface area.

Also of note, that certain floorstanders don't seem to have this identifying "box" sound - the Boston A400's didn't have it - they were a very wide, but relatively thin rectangular box....

View attachment 185171
(also noteable for having relatively small 8" woofers but two of them - they had great bass!)

I remember the annoyed look on a high end audio retailers face, when after less than 60 seconds listening to a very expensive set of speakers - I said "they sound like boxes" - In the next room he had a pair of Magnepan 3.7's set up.... listened to those for 60 seconds..... ahhhh that's more like it... settled in for a bit of a listening session.... I don't recall the "boxes" but they were priced up around $10k at the time.

This would have been in the late 90's - when I spent 4 years in NYC...

All of which is to open up the topic - what is it exactly that makes a box sound "boxy"

And what is it about those (rare) "boxes" that don't have that distinctive sound?

During my skint student years - I had small bookshelves... a set of AudioPro's and a set of Tandy/Radio Shack - cheap and cheerful - no serious vices, and no "boxy" sound! - Possibly because small boxes are more rigid, or their smaller radiating surface, makes the resonance less obvious?

That might lead to - how does one eliminate the boxy sound if a speaker has it?

(or is it so fundamental to the design, that it is best to move to a different speaker... as I did)
Modern boxes aren't boxy sounding. Yes, I agree they used to be, and that led to a big audible advantage for panels. The better newer systems have tamed boxiness caused by resonances and diffraction from the cabinets. Some have sculpted front panels to eliminate diffraction and use cabinet construction that largely eliminates audible resonances (aluminum, internal bracing, etc.).
 
Top Bottom