Hi, when reading a the "Get Better Sound" audio system set-up manual, I was intrigued by what the author Jim Smith claims about the 192 Hz to 384 Hz frequency region:
Apart from being curious, if your experience is similar, I am more interested to hear your opinion on what type of speaker enclosure might best take care of the 192 Hz to 384 Hz region.
I am about to build new speakers using 10" fullrange driver (http://commonsenseaudio.com/an10cfspecs.jpg). Forgive my ignorance, but I notice this particular driver has lowest impendance in the 192 Hz to 384 Hz region. What practical implications does this have?
Thank you for sharing..... Peter
Apart from being curious, if your experience is similar, I am more interested to hear your opinion on what type of speaker enclosure might best take care of the 192 Hz to 384 Hz region.
I am about to build new speakers using 10" fullrange driver (http://commonsenseaudio.com/an10cfspecs.jpg). Forgive my ignorance, but I notice this particular driver has lowest impendance in the 192 Hz to 384 Hz region. What practical implications does this have?
Thank you for sharing..... Peter
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Book "Get Better Sound"
Hi jerryo,
I have the book also and while not able to give you a "review", I can tell you that for me it proved a very cost effective treatment of "upgraditis". In audio world full of opinions and personal preferences, a little knowledge based on sound physical principles and confirmed by years of experience goes a long way. When seen as a book, it is definitely not cheap. When seen as (knowledge of) an audio component, I have not found a better value yet. It saved me hundreds of dollars potentially spent on "trial & error" or "plug & pray" upgrades to my audio system. Just my 2 cents.
Hi jerryo,
I have the book also and while not able to give you a "review", I can tell you that for me it proved a very cost effective treatment of "upgraditis". In audio world full of opinions and personal preferences, a little knowledge based on sound physical principles and confirmed by years of experience goes a long way. When seen as a book, it is definitely not cheap. When seen as (knowledge of) an audio component, I have not found a better value yet. It saved me hundreds of dollars potentially spent on "trial & error" or "plug & pray" upgrades to my audio system. Just my 2 cents.
Related question
On a related topic:
How much would you think that the sound of a speaker in the 200-400 Hz region is shaped by:
- frequency response of the driver
- cabinet
- room and room treatments?
I just presume it is a combination of all three factors but unlike in higher frequency region, the effect of the cabinet and the room may be stronger.
If so, does the enclosure play lesser/equal/greater role than the frequency response of the driver given by the manufacturer, particularly in the 200-400 Hz area?
Thanks for your thoughts.
On a related topic:
How much would you think that the sound of a speaker in the 200-400 Hz region is shaped by:
- frequency response of the driver
- cabinet
- room and room treatments?
I just presume it is a combination of all three factors but unlike in higher frequency region, the effect of the cabinet and the room may be stronger.
If so, does the enclosure play lesser/equal/greater role than the frequency response of the driver given by the manufacturer, particularly in the 200-400 Hz area?
Thanks for your thoughts.
Hi,
I think Jim is too restrictive and imprecise at the same time.
The fundamentals of many instruments and the human voice fall into this range.
I would personally say that it is important that this range is in the correct proportion compared to frequencies above and below, not to be flat in itself.
However I would add that it is the in room POWER RESPONSE and NOT the (pseudo)anechoic on axis frequency response that should be flat in this range. The on axis response if flat as well should be accounted as major bonus.
In general terms this implies a system with controlled directivity in this range, which pretty much means a large front horn, e.g. the big Avantgarde Trumpets Jim used to sell, or a dipole or a cardioid system. Conventional vented boxes, especially narrow fronted ones often cannot deliver this.
Looking quickly at the driver it would seem that it requires front and rear horn loading to offer a balanced frequency response, so I hope you intend to buildsuch a cabinet. A reflex box would give a most uneven frequency response.
As to impedance being lowest, it means this range will be somewhat suppressed when driving the speaker from an Amplifier with high output impedance (OTL, SET) compared to a conventional amplifier, nothing more and nothing less.
Ciao T
I think Jim is too restrictive and imprecise at the same time.
The fundamentals of many instruments and the human voice fall into this range.
I would personally say that it is important that this range is in the correct proportion compared to frequencies above and below, not to be flat in itself.
However I would add that it is the in room POWER RESPONSE and NOT the (pseudo)anechoic on axis frequency response that should be flat in this range. The on axis response if flat as well should be accounted as major bonus.
In general terms this implies a system with controlled directivity in this range, which pretty much means a large front horn, e.g. the big Avantgarde Trumpets Jim used to sell, or a dipole or a cardioid system. Conventional vented boxes, especially narrow fronted ones often cannot deliver this.
Looking quickly at the driver it would seem that it requires front and rear horn loading to offer a balanced frequency response, so I hope you intend to buildsuch a cabinet. A reflex box would give a most uneven frequency response.
As to impedance being lowest, it means this range will be somewhat suppressed when driving the speaker from an Amplifier with high output impedance (OTL, SET) compared to a conventional amplifier, nothing more and nothing less.
Ciao T
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Thank you Thorsten for bringing the excerpt into some perspective.
As for the cabinet for the AN10" cast frame drivers, I have narrowed down the choices preliminary to:
(1) horns S.P.Q.R. EZ10
The S.P.Q.R. EZ10 S.P.Q.R. Acoustics
This speaker was not really reviewed by anyone but I am intrigued by a horn-type enclosure for 10" driver that is actually smaller than 140 cm
(2) Decware HDT design with additional baffle to make it possible to fit 10" drivers in the 8" enclosure - in its original form for 8" drivers is this design well tested.
Would you say one option is better than the other? Does either of them offer better opportunities for tweaking after they are built? I am more or less convinced not to build bass reflex speakers shown at commonsence website.
As for the cabinet for the AN10" cast frame drivers, I have narrowed down the choices preliminary to:
(1) horns S.P.Q.R. EZ10
The S.P.Q.R. EZ10 S.P.Q.R. Acoustics
This speaker was not really reviewed by anyone but I am intrigued by a horn-type enclosure for 10" driver that is actually smaller than 140 cm
(2) Decware HDT design with additional baffle to make it possible to fit 10" drivers in the 8" enclosure - in its original form for 8" drivers is this design well tested.
Would you say one option is better than the other? Does either of them offer better opportunities for tweaking after they are built? I am more or less convinced not to build bass reflex speakers shown at commonsence website.
Hi,
Hmm, on paper this looks okay. This kind of bass bin is not uncommon in PA Apps.
What you need to understand is the following:
1) At low midrange frequencies (200Hz-1KHz) the AN driver has around 94dB/2.83V/1m SPL (as per datasheet).
2) At 1KHz the SPL shelves up by around 4dB to 98dB/2.83V/1m and exceeds 100dB/2.83V by the time we reach 5KHz.
3) Above around 5KHz the SPL rises further to reach 106dB/2.83V/1m though this is in part compensated for by very early HF rolloff off axis. At 30degrees angle the HF boost is no longer observable, instead the response above 1KHz has a broadly balanced, if very ragged response (many cancellation dips) with a steep rolloff above 10KHz.
So, on axis the driver has a Frequency response that is boosted by 4dB at 2KHz compared to the fundamental range and by 12dB at 10KHz. This is quite comparable with taking a conventional frequency response speaker and turning treble tone control up all the way on traditional hifi gear that has such controls.
Those that have tried to equalise these problems with passive circuits have always found that they kill the sound quality that made these drivers interesting in the first place.
The acoustic solution is to make a so-called compound horn. That is a Horn that loads the front and back of the driver.
The front loaded horn boosts the range below 1KHz and down to it's cutoff by around 4dB, to produce a balanced sound. If you keep the front horn size manageable you are looking normally at 250...300Hz cutoff.
An added benefit is that such a horn will have a much better controlled directivity.
Then the rear horn must be designed to take over where the front horn leaves off and give enough gain to match the now quite high efficiency, but limited bandwidth front output of the hornloaded driver. Such designs also tend to have a more limited HF extension (but less of a "bright spot") then direct radiating designs, so a super tweeter may be needed to get the top right.
I used to run such a system with Lowther Drivers and Beauhorn Virtuoso Enclosures (the result an evenly balanced response in the 50..100Hz - 12..14KHz range, around 101dB/2.83V/1m), plus Supertweeters and Subwoofers. You can read more here:
Thorsten Loesch: The Beauhorn Virtuoso
Any design that only loads the back of the driver will not be able to operate high enough to add enough SPL up to 1KHz, so in the end the range between the rear horn cutoff (usually around 200-300Hz) and 1KHz is left depressed, which is the very sound Jim Smith indites in his notes. And which I found intolerable with Lowthers and their ilk in rearload only enclosures (and I heard a wide range of these at diverse occasions, non "worked").
An alternative would be to use something like my D3L2QD system, which was specifically intended to overcome the issues. I see that Mr. Dicks has since somewhat picked up on my idea (I kind of rubbed his face in the idea while showing just how bad the bass reflex boxes he proposed where) in his "ambience" cabinets. However D3L2QD explicitly requires drivers with very different parameters, now two of the same, so his approach does not get it quite right.
If I where to build a speaker nowadays using drivers like the Lowther/Audio Nirvana/Fostex twin cone drivers (not that I would, I would simply save myself the pain and buy the vastly superior offerings from PHY-HP or Supravox that do not make the kind of compromises the others make), I would probably look at a smaller diameter driver (6.5 to 8") and use it in a compact D3L2QD system, tuned to handle the signal down to around 80...120Hz with an active sub below that.
It would be possible to make this into a quite compact tower speaker with good efficiency and rather low LF extension.
Ciao T
Hmm, on paper this looks okay. This kind of bass bin is not uncommon in PA Apps.
What you need to understand is the following:
1) At low midrange frequencies (200Hz-1KHz) the AN driver has around 94dB/2.83V/1m SPL (as per datasheet).
2) At 1KHz the SPL shelves up by around 4dB to 98dB/2.83V/1m and exceeds 100dB/2.83V by the time we reach 5KHz.
3) Above around 5KHz the SPL rises further to reach 106dB/2.83V/1m though this is in part compensated for by very early HF rolloff off axis. At 30degrees angle the HF boost is no longer observable, instead the response above 1KHz has a broadly balanced, if very ragged response (many cancellation dips) with a steep rolloff above 10KHz.
So, on axis the driver has a Frequency response that is boosted by 4dB at 2KHz compared to the fundamental range and by 12dB at 10KHz. This is quite comparable with taking a conventional frequency response speaker and turning treble tone control up all the way on traditional hifi gear that has such controls.
Those that have tried to equalise these problems with passive circuits have always found that they kill the sound quality that made these drivers interesting in the first place.
The acoustic solution is to make a so-called compound horn. That is a Horn that loads the front and back of the driver.
The front loaded horn boosts the range below 1KHz and down to it's cutoff by around 4dB, to produce a balanced sound. If you keep the front horn size manageable you are looking normally at 250...300Hz cutoff.
An added benefit is that such a horn will have a much better controlled directivity.
Then the rear horn must be designed to take over where the front horn leaves off and give enough gain to match the now quite high efficiency, but limited bandwidth front output of the hornloaded driver. Such designs also tend to have a more limited HF extension (but less of a "bright spot") then direct radiating designs, so a super tweeter may be needed to get the top right.
I used to run such a system with Lowther Drivers and Beauhorn Virtuoso Enclosures (the result an evenly balanced response in the 50..100Hz - 12..14KHz range, around 101dB/2.83V/1m), plus Supertweeters and Subwoofers. You can read more here:
Thorsten Loesch: The Beauhorn Virtuoso
Any design that only loads the back of the driver will not be able to operate high enough to add enough SPL up to 1KHz, so in the end the range between the rear horn cutoff (usually around 200-300Hz) and 1KHz is left depressed, which is the very sound Jim Smith indites in his notes. And which I found intolerable with Lowthers and their ilk in rearload only enclosures (and I heard a wide range of these at diverse occasions, non "worked").
An alternative would be to use something like my D3L2QD system, which was specifically intended to overcome the issues. I see that Mr. Dicks has since somewhat picked up on my idea (I kind of rubbed his face in the idea while showing just how bad the bass reflex boxes he proposed where) in his "ambience" cabinets. However D3L2QD explicitly requires drivers with very different parameters, now two of the same, so his approach does not get it quite right.
If I where to build a speaker nowadays using drivers like the Lowther/Audio Nirvana/Fostex twin cone drivers (not that I would, I would simply save myself the pain and buy the vastly superior offerings from PHY-HP or Supravox that do not make the kind of compromises the others make), I would probably look at a smaller diameter driver (6.5 to 8") and use it in a compact D3L2QD system, tuned to handle the signal down to around 80...120Hz with an active sub below that.
It would be possible to make this into a quite compact tower speaker with good efficiency and rather low LF extension.
Ciao T
Hi Thorsten,
messages like yours allow us newbies to better understand the basics/principles. Thank you for taking the time for sharing this.
Working with what I have (AN10) I tend to accept the SPQR EZ10 design (the in-room frequency plot using exactly these drivers does not look at all bad to me) but now I understand better the limitations and the function of front loaded horn. Indeed, with the speakers driven by Decware Zen amp (SET design, best in the 2-4 ohm range) I may still have issues with these 8 ohm speakers. I am glad to have a push-pull 8 ohm alternative to see what I would be missing.
messages like yours allow us newbies to better understand the basics/principles. Thank you for taking the time for sharing this.
Working with what I have (AN10) I tend to accept the SPQR EZ10 design (the in-room frequency plot using exactly these drivers does not look at all bad to me) but now I understand better the limitations and the function of front loaded horn. Indeed, with the speakers driven by Decware Zen amp (SET design, best in the 2-4 ohm range) I may still have issues with these 8 ohm speakers. I am glad to have a push-pull 8 ohm alternative to see what I would be missing.
Well, C4 is nowadays defined as 261.63Hz and the octave centered there is 185-370Hz
Historically, middle C has varied between approximately 226 and 285 Hz. The author's value lies in this range.I will say that I think a lack of energy in this range does seem to pull the life out of the music. This is sort of the vocal power range - a lot of fundamentals and overtones are in this range. I recall hearing a friend's system which had a dip in this range and one female vocal in particular seemed to really lose something until he fixed it.
Honestly, I think the author's way of phrasing this tends to make it seem more magical/inexplicable than it really is. I like Thorsten's phrasing better. It is an octave to octave balance issue.
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Hi,
Agreed, the EZ10 looks reasonable, though there is a lot response ripple.
Arguably all domestic horns have this kind of problem to varying degrees, they are generally to short and have too small a mouth size to control these ripples well.
Hence again my advise to consider something like D3L2QD with a sub.
Ciao T
Agreed, the EZ10 looks reasonable, though there is a lot response ripple.
Arguably all domestic horns have this kind of problem to varying degrees, they are generally to short and have too small a mouth size to control these ripples well.
Hence again my advise to consider something like D3L2QD with a sub.
Ciao T
Agree with Thorsten and Ron on the balance and power response thing.
I do not own the book. But I had a good look at the website and would guess the book contains some pretty good advice. It should be handy to own.
However, two things struck me as funny.
I do not own the book. But I had a good look at the website and would guess the book contains some pretty good advice. It should be handy to own.
However, two things struck me as funny.
- Smith criticizes all those "so called experts" on the forums. But he sets himself up as an expert - who wants to sell you a book. Hmmmmm.....
- Jim Smith was the USA distributer of Avantgarde Audio until 2005. I visited the Avantgarde room at the Montreal show in 2008. It was awful, truly bad. I think they needed Jim Smith back real quick.
Thorsten,
I understand that it is a compromise to accept response ripples of this kind.
From what I read (not measured), the room and room treatments may have even much more profound impact on the frequence response - for the good or for the bad. Do you think that ripples in the mid-bass area could be addressed with diffusers, bass traps, and similar room treatments (even if less ideal than not having to deal with this in the first place)?
I understand that it is a compromise to accept response ripples of this kind.
From what I read (not measured), the room and room treatments may have even much more profound impact on the frequence response - for the good or for the bad. Do you think that ripples in the mid-bass area could be addressed with diffusers, bass traps, and similar room treatments (even if less ideal than not having to deal with this in the first place)?
Hi,
Sure. But it makes the job even harder if you start with something that has +/-3dB response ripples (likely more than that actually).
Of course everything is a compromise.
To deal with low frequencies with passive absorbers generally means plate-type "anti-resonators", So-called bass traps can help add a bit of danmping but not a lot (consider wavelength and the fact that to do anything the absorbent material needs to be an appreciable percentage of the length thick...
Ciao T
Sure. But it makes the job even harder if you start with something that has +/-3dB response ripples (likely more than that actually).
Of course everything is a compromise.
To deal with low frequencies with passive absorbers generally means plate-type "anti-resonators", So-called bass traps can help add a bit of danmping but not a lot (consider wavelength and the fact that to do anything the absorbent material needs to be an appreciable percentage of the length thick...
Ciao T
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