Hello all,
I am looking for some ways to extend the low end of a sealed bass unit, at the cost of efficiency. I know of the large capacitor trick, but that is not enough extension.
On the Manzanita thread in diyaudio, a large inductor giving a 1st order low pass filter well below 100Hz has worked wonders for a dipole. This not only sounds great but on simulating with Martin's passive U-frame sheets looks absolutely flat. I tried to simulate the same idea with a sealed cabinet, as the low end rolloff is similar though not the same as a dipole. Used Martin's sealed passive TL sheets but not even close to a flat low end response. Tried Jeff Bagby's Passive Crossover Designer...no luck.
Is there any other passive contouring trick to extend the LF end of a sealed cabinet.
Thanks.
I am looking for some ways to extend the low end of a sealed bass unit, at the cost of efficiency. I know of the large capacitor trick, but that is not enough extension.
On the Manzanita thread in diyaudio, a large inductor giving a 1st order low pass filter well below 100Hz has worked wonders for a dipole. This not only sounds great but on simulating with Martin's passive U-frame sheets looks absolutely flat. I tried to simulate the same idea with a sealed cabinet, as the low end rolloff is similar though not the same as a dipole. Used Martin's sealed passive TL sheets but not even close to a flat low end response. Tried Jeff Bagby's Passive Crossover Designer...no luck.
Is there any other passive contouring trick to extend the LF end of a sealed cabinet.
Thanks.
One classic technique used to extend bass response (at expense of eff.) is to add mass to the cone. This was elegantly done on a commercial scale years ago by Peter Snell in his infamous Model A and others. He poured resin around the dust cap which solidified. It lowers Fs in proportion to the amount of weight added up to a point.
Look at the picture on the last page of the download at this link. http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4762
Look at the picture on the last page of the download at this link. http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4762
Last edited:
Hi,
For a sealed cabinet your best bet is a passive 1st order step filter at line
level, which usually interacts with other high pass sections so +12dB
might end up being only +6dB, or an active peaking 2nd order high
pass, can be build around the line amplifier or power amplifier.
There is no passive EQ at speaker level that works well for bass other
than proper baffle step compensation AFAIK. Sealed and vented boxes
impedance peaks prevent any form of passive low bass manipulation.
rgds, sreten.
For a sealed cabinet your best bet is a passive 1st order step filter at line
level, which usually interacts with other high pass sections so +12dB
might end up being only +6dB, or an active peaking 2nd order high
pass, can be build around the line amplifier or power amplifier.
There is no passive EQ at speaker level that works well for bass other
than proper baffle step compensation AFAIK. Sealed and vented boxes
impedance peaks prevent any form of passive low bass manipulation.
rgds, sreten.
Are you referring to an upstream, line level BSC filter? Here's a link to one designed for a vintage Advent speaker (closed box). What it does basically, is eq the mid to high range, bringing it down so the bass is in better balance with the rest of the response.
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2692
Check out post #133 and #135 (schematic of the LL BSC circuit)
Last edited:
Hi,
Very leading question, and of course I'm not, though its a valid approach.
It misses the point completely that BSC can easily be implemented passively.
rgds, sreten.
Last edited:
in series with the speaker wire. 
Is the box properly stuffed?
Perhaps using an appropriate density of fill would give you a few Hz
In the long run using the box programs and buying a better driver is cheaper and easier and so much is room dependent that i would be guessing if I offered any more advice without knowing all of the parameters
Perhaps using an appropriate density of fill would give you a few Hz
In the long run using the box programs and buying a better driver is cheaper and easier and so much is room dependent that i would be guessing if I offered any more advice without knowing all of the parameters
Do you think the OEM just did not want deeper flat bass? You are trying to cheat physics. In my experience, physics always wins.
Mass does lower Fs at the expense of HF extension and efficiency.
Stuffing will help a tiny bit with Q, but nothing dramatic. ( may have other positive effects on reflections)
Knocking down the top end shifts the overall balance to give the sound some weight at the expense of efficiency.
Putting the speakers against the wall, or in a corner gives reinforcement to the bass that is there, not deeper.
Building a new box with different alignment ( ported that means) will give a lot more LF extension, if the driver is suitable.
Why must this be passive? Just a little active eq can give a good 5 to 10 Hz real extension without risking the limits of the driver. Look at the circuit for sub eq on ESP. Not the LT, the more flexible bass eq circuit.
There is only one really good method that works every time. That is a terminus replacement. Replace the thing at the end of the speaker wires with one that goes deeper. There ain't no free lunch!
Mass does lower Fs at the expense of HF extension and efficiency.
Stuffing will help a tiny bit with Q, but nothing dramatic. ( may have other positive effects on reflections)
Knocking down the top end shifts the overall balance to give the sound some weight at the expense of efficiency.
Putting the speakers against the wall, or in a corner gives reinforcement to the bass that is there, not deeper.
Building a new box with different alignment ( ported that means) will give a lot more LF extension, if the driver is suitable.
Why must this be passive? Just a little active eq can give a good 5 to 10 Hz real extension without risking the limits of the driver. Look at the circuit for sub eq on ESP. Not the LT, the more flexible bass eq circuit.
There is only one really good method that works every time. That is a terminus replacement. Replace the thing at the end of the speaker wires with one that goes deeper. There ain't no free lunch!
Thanks everybody for the input.
I have tried the series resistor to increase driver Qes, large cap to cause resonance at the knee and lead to bass boost at the low end.
My purpose is to have the smallest possible bookshelf size speaker with bass extended down to at least 30Hz flat. I am not cheating Hoffman Law and so sacrificing efficiency to get bass extension and small size.
The easiest way I can think of is Linkwitz transform, but that is an active method. Going active is cheap now but as this speaker is not to be used by me but my father who prefers a plug and play solution, the prime consideration is convenience.
My best guess to do this, was a passive BSC filter after the amplifier, starting at about 60Hz, which is the cabinet resonance frequency and start of the cutoff in the simulations. Using Martins BSC designer on the closed TL sheet, if I try a frequency this low, although there is desired attenuation at the mid-high frequencies but there is minimal attenuation at the system resonant frequency which becomes even more peaky after inserting the BSC filter. Wonder if it is causing a superimposed electrical resonance at the cabinet resonance, increasing the resonant peak.
I have tried the series resistor to increase driver Qes, large cap to cause resonance at the knee and lead to bass boost at the low end.
My purpose is to have the smallest possible bookshelf size speaker with bass extended down to at least 30Hz flat. I am not cheating Hoffman Law and so sacrificing efficiency to get bass extension and small size.
The easiest way I can think of is Linkwitz transform, but that is an active method. Going active is cheap now but as this speaker is not to be used by me but my father who prefers a plug and play solution, the prime consideration is convenience.
My best guess to do this, was a passive BSC filter after the amplifier, starting at about 60Hz, which is the cabinet resonance frequency and start of the cutoff in the simulations. Using Martins BSC designer on the closed TL sheet, if I try a frequency this low, although there is desired attenuation at the mid-high frequencies but there is minimal attenuation at the system resonant frequency which becomes even more peaky after inserting the BSC filter. Wonder if it is causing a superimposed electrical resonance at the cabinet resonance, increasing the resonant peak.
Last edited:
Will the speaker actually end up on a shelf near a wall? If so, BCS won't be necessary. My 'Intimates' speaker cabs are vented 1/2 liter with a 15W SS bass/mid that gets down to 40 hz. and that's plenty of bass for most music listening.
Hi,
Any passive circuits in the bass region simply won't work due to driver
resonances. Small drivers designed for very low efficiency and hence
decent bass are very rare due to the popularity of AV systems.
Subs and sats is the way to go if you want decent deep bass at a
satifying level. You can EQ the bass of small speakers, you can't
change how (not) loud a small driver goes in the bass.
No subs you need decent box volume for low bass and
slim floorstanders are an obvious way of achieving this.
This design goes pretty deep (I'd detune the port a little) :
https://sites.google.com/site/undefinition/diy/amiga
rgds, sreten.
Any passive circuits in the bass region simply won't work due to driver
resonances. Small drivers designed for very low efficiency and hence
decent bass are very rare due to the popularity of AV systems.
Subs and sats is the way to go if you want decent deep bass at a
satifying level. You can EQ the bass of small speakers, you can't
change how (not) loud a small driver goes in the bass.
No subs you need decent box volume for low bass and
slim floorstanders are an obvious way of achieving this.
This design goes pretty deep (I'd detune the port a little) :
https://sites.google.com/site/undefinition/diy/amiga
rgds, sreten.
That sounds impressive.
Do you posting some details about your Intimate speakers.
Thanks.
My purpose of a BSC kind of filter is not in the traditional sense to control the rising mids due to transitioning 4pi to 2pi radiation. I would use the BSC filter in the 4pi radiation region only at about 40-60 Hz, to reduce the midbass to a level of the lower bass spectrum.
Last edited:
Hi,
I keep telling you your plan won't work and you keep on ignoring that information.
The only way to achieve good low bass from a compact speaker is :
An overdamped vented low alignment, the vent hugely increases (+6dB)
low bass power handling and maximum clean low bass SPL.
The overdamped bass alignment should look quasi first order roll-off.
The speaker should have full midrange BSC for free space mounting.
Placing the speaker away from side and rear walls will allow the slow bass
roll-off to interact with the room boundaries only at low frequencies, so
your properly using room gain to boost the bass extension and SPL.
Basso Profundo | Stereophile.com
http://www.stereophile.com/content/who-stole-bass-no-one-stole-bass-letters
Such placement also gives by far the best midrange sound quality,
as well as the most even bass response, limiting excessive drive
of the troublesome room modes. Listening position will also
affect the apparent deep bass for this sort of bass regimen.
The Dayton RS180 models extremely well in a 24L boxed tuned to 30Hz,
with a -6dB down point at 30Hz and a very nice tapered roll-off of 2dB/
octave 120Hz to 60Hz and 4dB/octave 60Hz to 30Hz. (-3dB@44Hz).
30L is actually too big for this driver to get a nice tapered roll-off.
Optimally placed in-room to utilise room gain it will go down flat to 30Hz,
with a realistic in-room cut-off of 25Hz* (-9dB point of the above alignment),
and produce quite astonishingly deep and tactile bass to those unfamiliar
with this approach to optimising the bass end of relatively small speakers.
(Though results are room size and room ratios dependent.)
I'll repeat though the speakers must have proper BSC to sound balanced.
http://sound.westhost.com/bafflestep.htm
rgds, sreten.
* Power handling drops off a lot as you move away below the port frequency.
I keep telling you your plan won't work and you keep on ignoring that information.
The only way to achieve good low bass from a compact speaker is :
An overdamped vented low alignment, the vent hugely increases (+6dB)
low bass power handling and maximum clean low bass SPL.
The overdamped bass alignment should look quasi first order roll-off.
The speaker should have full midrange BSC for free space mounting.
Placing the speaker away from side and rear walls will allow the slow bass
roll-off to interact with the room boundaries only at low frequencies, so
your properly using room gain to boost the bass extension and SPL.
Basso Profundo | Stereophile.com
http://www.stereophile.com/content/who-stole-bass-no-one-stole-bass-letters
Such placement also gives by far the best midrange sound quality,
as well as the most even bass response, limiting excessive drive
of the troublesome room modes. Listening position will also
affect the apparent deep bass for this sort of bass regimen.
The Dayton RS180 models extremely well in a 24L boxed tuned to 30Hz,
with a -6dB down point at 30Hz and a very nice tapered roll-off of 2dB/
octave 120Hz to 60Hz and 4dB/octave 60Hz to 30Hz. (-3dB@44Hz).
30L is actually too big for this driver to get a nice tapered roll-off.
Optimally placed in-room to utilise room gain it will go down flat to 30Hz,
with a realistic in-room cut-off of 25Hz* (-9dB point of the above alignment),
and produce quite astonishingly deep and tactile bass to those unfamiliar
with this approach to optimising the bass end of relatively small speakers.
(Though results are room size and room ratios dependent.)
I'll repeat though the speakers must have proper BSC to sound balanced.
http://sound.westhost.com/bafflestep.htm
rgds, sreten.
* Power handling drops off a lot as you move away below the port frequency.
Last edited:
Here ya go! Introducing the "INTIMATES" (high WAF & quality sound)
Also visit my photobucket links for more details.
p.s. these are definitely not your budget speakers. Built cost in the $1K to $1.5k range. Eff. 84 dB @ 2.83V pink noise. They'll need some power to make them sing. Mine sing very comfortably with bridged Amp-100 amps driving ea. (160 WPC)
Last edited:
OP, Please read the first line of post 14.
We call these things the LAWS OF PHYSICS. There is a reason for this. The only small speakers I know of that produce deep base are my Grado 90's. Headphones. Get real. don't you think every OEM would build a 6L box that fills a stadium at 30 Hz and 95 dB if it was possible? Sorry, it isn't.
The smallest speaker that goes pretty deep I know of is the 5" Scan Speak. A far more practical approach is to build a sub that is stealthy. Many have been done that fit under sofa's, in closets, attic, wall cavity or look like furniture. USE the laws of physics, don't try and reinvent them.
We call these things the LAWS OF PHYSICS. There is a reason for this. The only small speakers I know of that produce deep base are my Grado 90's. Headphones. Get real. don't you think every OEM would build a 6L box that fills a stadium at 30 Hz and 95 dB if it was possible? Sorry, it isn't.
The smallest speaker that goes pretty deep I know of is the 5" Scan Speak. A far more practical approach is to build a sub that is stealthy. Many have been done that fit under sofa's, in closets, attic, wall cavity or look like furniture. USE the laws of physics, don't try and reinvent them.
Thanks Sreten, for pointing out the effects of room gain in the bass region. The low Q vented bass alignment is a great idea....but also needs a big box.
Tvgreek, I would never try to cheat laws of physics...because that is impossible ! With some electronic help indeed small bass units are feasible, eg Sunfire Truesub. Once electronically assisted speakers are designed, acoustic laws of physics, though not being violated or reinvented, are being circumvented by electronic solutions like the linkwitz transform (LT).
To extend the LF end of a small sealed speaker, my search was for an electronic solution using passive components, unlike the LT that needs active electronics. The LT applies a positive shelving filter to the low end (say below 60 Hz), with an active circuit and boosts the low end. I was hoping it should be possible to apply a negative shelf (say above 60Hz) with a passive circuit after the amplifier and cut down the midbass. Efficiency will be sacrificed drastically, which is the acceptable cost. As per the laws of physics again, the bass SPL is limited only by woofer displacement, if sufficient amplifier power is not a problem.
Tvgreek, I would never try to cheat laws of physics...because that is impossible ! With some electronic help indeed small bass units are feasible, eg Sunfire Truesub. Once electronically assisted speakers are designed, acoustic laws of physics, though not being violated or reinvented, are being circumvented by electronic solutions like the linkwitz transform (LT).
To extend the LF end of a small sealed speaker, my search was for an electronic solution using passive components, unlike the LT that needs active electronics. The LT applies a positive shelving filter to the low end (say below 60 Hz), with an active circuit and boosts the low end. I was hoping it should be possible to apply a negative shelf (say above 60Hz) with a passive circuit after the amplifier and cut down the midbass. Efficiency will be sacrificed drastically, which is the acceptable cost. As per the laws of physics again, the bass SPL is limited only by woofer displacement, if sufficient amplifier power is not a problem.
Hi,
Your simply not listening, your solution cannot work.
Are you hoping someone will eventually agree with you
(wrongly) so you can erroneously proceed with your plan ?
You can only lead a horse to the water ....
You can't circumvent the full laws of physics full stop, only
manipulate them, and you simply can't make small speakers
you can stick anywhere you like that will do 30Hz effectively.
As your building speakers for someone else quite frankly your
prelidictions aren't really the point, and are very misplaced.
rgds, sreten.
Your simply not listening, your solution cannot work.
Are you hoping someone will eventually agree with you
(wrongly) so you can erroneously proceed with your plan ?
You can only lead a horse to the water ....
You can't circumvent the full laws of physics full stop, only
manipulate them, and you simply can't make small speakers
you can stick anywhere you like that will do 30Hz effectively.
As your building speakers for someone else quite frankly your
prelidictions aren't really the point, and are very misplaced.
rgds, sreten.
Last edited:
The Sunfire was a horrid thing with massive displacement and tremendous active eq. It pretty much proves what Sreten and I are saying.
If you would please go read what an LT is, you would see it is not just an eq, it is a Q management filter. Don't take my word for it, take Siegfried's. That is why I suggested the ESP active eq filter.
If all you want is a shelving filter, that is easy. Just a coil and a resistor. A really big coil. Use any BSC calculator and set the first pole at about 75 Hz. You may need to take out a loan for the inductor. Something like 12mH. Those darn laws of physics again.
If you would please go read what an LT is, you would see it is not just an eq, it is a Q management filter. Don't take my word for it, take Siegfried's. That is why I suggested the ESP active eq filter.
If all you want is a shelving filter, that is easy. Just a coil and a resistor. A really big coil. Use any BSC calculator and set the first pole at about 75 Hz. You may need to take out a loan for the inductor. Something like 12mH. Those darn laws of physics again.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.