Yup (shudder)
Looks like we've arrived at the usual point. Reitterating the points made thus far, then assuming you do not wish the box material to audibly contribute to the sound (and in some cases, people do), then there are two choices, accepting the fact that it's a practical impossibility to completely erradicate panel resonance.
1) you can go the high-mass approach, and push the panel's natural resonance frequency downward, below the cabinet's operational passband, and 2)
2) You can take the opposite approach, make them as light and stiff as possible, raising the natural resonance frequency of panels to a point above the cabinet's operational passband.
Both work. The latter is preferable as it releases energy more quickly. It does indeed ring like a bell, but the natural resonances are never strongly activated, as they're above the zone the box is operating in. CRS is ideal for this & impressively efficienct (12 - 14ga according to GM IIRC, & he should know, given how long he worked with the stuff). You can go further with other materials, but frankly, there wouldn't be much point.
Looks like we've arrived at the usual point. Reitterating the points made thus far, then assuming you do not wish the box material to audibly contribute to the sound (and in some cases, people do), then there are two choices, accepting the fact that it's a practical impossibility to completely erradicate panel resonance.
1) you can go the high-mass approach, and push the panel's natural resonance frequency downward, below the cabinet's operational passband, and 2)
2) You can take the opposite approach, make them as light and stiff as possible, raising the natural resonance frequency of panels to a point above the cabinet's operational passband.
Both work. The latter is preferable as it releases energy more quickly. It does indeed ring like a bell, but the natural resonances are never strongly activated, as they're above the zone the box is operating in. CRS is ideal for this & impressively efficienct (12 - 14ga according to GM IIRC, & he should know, given how long he worked with the stuff). You can go further with other materials, but frankly, there wouldn't be much point.
Thor BSC
-bump-
Maybe I should state my intentions...
I'm interested in building a Thor varient with active crossover. I have a couple of NAD amps laying around (125wpc) to drive the W18's, and would like to build either a Leach amp or a Rod Elliott design to drive the Milleniums.
Elliots P09 crossover seems like it would be ideal for this application (2-way 24db/Oct.), but I'm thinking that a BSC circuit will have to be added to it. I know the Thor varients have all kept the original baffle size in order to use the original crossover (because of the BS correction?). Can anyone tell me what the calculated BS frequency is? I can't seem to find the info anywhere.
Or maybe I should learn how to figure it out for myself
Thanks,
Rob
-bump-
Maybe I should state my intentions...
I'm interested in building a Thor varient with active crossover. I have a couple of NAD amps laying around (125wpc) to drive the W18's, and would like to build either a Leach amp or a Rod Elliott design to drive the Milleniums.
Elliots P09 crossover seems like it would be ideal for this application (2-way 24db/Oct.), but I'm thinking that a BSC circuit will have to be added to it. I know the Thor varients have all kept the original baffle size in order to use the original crossover (because of the BS correction?). Can anyone tell me what the calculated BS frequency is? I can't seem to find the info anywhere.
Or maybe I should learn how to figure it out for myself
Thanks,
Rob
Re: Thor BSC
Rob,
The x-over frequency between the tweeter and the W18's @ 24dB/oct can be anywhere between 1200 and 3000Hz.
Go lower and the distortion will increase at the tweeter, go higher and you will run into problems with the W18's resonance peak @ 4800Hz.
There is a sweet spot where the dispersion at the x-over frequency of both the tweeter and the W18's blend in best and makes it impossible to hear the transition from woofer to tweeter. This is close to the X-over frequency of the original design.
I build the original Thor design with the original passive filters. Currently I'm building active filters and will use a Bessel 24dB at 1800Hz with a baflestep correcttion at ~400Hz, a notchfilter to supress the peak @ 4800Hz (supressed 45 dB minimum) and an all-pass filter to correct the time offset of the tweeter.
I'm going to use 6 amplifiers and will drive each speaker with a separate amp (4xAleph30 and 2x mini-Aleph)
rob3262 said:-bump-
Maybe I should state my intentions...
I'm interested in building a Thor varient with active crossover. I have a couple of NAD amps laying around (125wpc) to drive the W18's, and would like to build either a Leach amp or a Rod Elliott design to drive the Milleniums.
Elliots P09 crossover seems like it would be ideal for this application (2-way 24db/Oct.), but I'm thinking that a BSC circuit will have to be added to it. I know the Thor varients have all kept the original baffle size in order to use the original crossover (because of the BS correction?). Can anyone tell me what the calculated BS frequency is? I can't seem to find the info anywhere.
Or maybe I should learn how to figure it out for myself
Thanks,
Rob
Rob,
The x-over frequency between the tweeter and the W18's @ 24dB/oct can be anywhere between 1200 and 3000Hz.
Go lower and the distortion will increase at the tweeter, go higher and you will run into problems with the W18's resonance peak @ 4800Hz.
There is a sweet spot where the dispersion at the x-over frequency of both the tweeter and the W18's blend in best and makes it impossible to hear the transition from woofer to tweeter. This is close to the X-over frequency of the original design.
I build the original Thor design with the original passive filters. Currently I'm building active filters and will use a Bessel 24dB at 1800Hz with a baflestep correcttion at ~400Hz, a notchfilter to supress the peak @ 4800Hz (supressed 45 dB minimum) and an all-pass filter to correct the time offset of the tweeter.
I'm going to use 6 amplifiers and will drive each speaker with a separate amp (4xAleph30 and 2x mini-Aleph)
Speaking of a 6 channel amps: http://www.emotiva.com/lpa1.html
If I could afford it, this would be my next purchase... it's not a bad deal at all!!! Look at the specs and check out the weight of that monster...
If I could afford it, this would be my next purchase... it's not a bad deal at all!!! Look at the specs and check out the weight of that monster...
Re: Re: Thor BSC
Thanks Tarasque, very helpful info. I stumbled upon Martin King's writeup on the subject BSC_Sizing and gained some knowledge.
I hadn't considered the exact crossover frequency yet. 1800hz won't be on the low side? I'm interested in your choices for this design, if you wouldn't mind expanding a bit. I'm considering a 24dB LR configuration, you've selected Bessel. What advantage(s) does that provide? Also, if you could explain the time offset and all-pass filter correction of it
I'm glad to hear someone else going active on the Thor. I'll look forward to hearing about your results. How many watts are your Alephs? (questions... questions...)
Thanks,
Rob
Tarasque said:
Thanks Tarasque, very helpful info. I stumbled upon Martin King's writeup on the subject BSC_Sizing and gained some knowledge.
I hadn't considered the exact crossover frequency yet. 1800hz won't be on the low side? I'm interested in your choices for this design, if you wouldn't mind expanding a bit. I'm considering a 24dB LR configuration, you've selected Bessel. What advantage(s) does that provide? Also, if you could explain the time offset and all-pass filter correction of it
I'm glad to hear someone else going active on the Thor. I'll look forward to hearing about your results. How many watts are your Alephs? (questions... questions...)
Thanks,
Rob
Re: Re: Re: Thor BSC
Not at 24dB. I selected bessel because of the smooth transitions both in amplitude as well as the time domain.
The A30 are 50W (pimped supplies) and the mini's are 20W (see below)
See: http://passdiy.com/gallery/amini-p5.htm
rob3262 said:
Not at 24dB. I selected bessel because of the smooth transitions both in amplitude as well as the time domain.
The A30 are 50W (pimped supplies) and the mini's are 20W (see below)
See: http://passdiy.com/gallery/amini-p5.htm
An externally hosted image should be here but it was not working when we last tested it.
Thor
Nice monoblocks! The NAD 716 torroidals don't look nearly as substantail (though the amps should provide sufficient headroom for my purposes). You'll surely spent a few $$ a month just to have them at idle power.
Renron,
You mention the 'what if' of a larger cabinet. After listening for the last 6months or so, are you satisfied with the low end or would you trade some response ripple for a deaper tone if you could turn back time? I do have to say that your curved cabinets are absolutely beautiful
- Rob
Tarasque said:
Nice monoblocks! The NAD 716 torroidals don't look nearly as substantail (though the amps should provide sufficient headroom for my purposes). You'll surely spent a few $$ a month just to have them at idle power.
Renron,
You mention the 'what if' of a larger cabinet. After listening for the last 6months or so, are you satisfied with the low end or would you trade some response ripple for a deaper tone if you could turn back time? I do have to say that your curved cabinets are absolutely beautiful
- Rob
Re: Thor
Rob,
Thank you for the compliment on the speakers. They were a labor of love and I enjoy looking (and listening) to them everyday. Would I make them bigger?
Maybe.
They are quite tall in comparison to other speakers, and the tallest I could get away with, considering the WAF
.
I am not a Bass hound, but I do enjoy the subtleties in the music, whether it is the squeaking fingers on the frets of a guitar, the shimmering of a symbol or the melody from the bass guitar that I never heard before.
Back to your question, I'm extremely pleased with the sound and feel it is balanced and not lacking in the bass department given the size of the mid-woofers.
Is a sub-woofer needed to fill in the bottom end when enjoying Eric Clapton or critical listening sessions? No.
Is a sub-woofer needed for HT? Absolutely, nothing beats the rumbling/shaking of the couch when the plane/car/explosion reaches it's crescendo.
A quick check with my RS (non calibrated) digital db meter says;
Hz Db
10 63
20 72
30 75
40 73
50 69
60 68
70 68
80 72
90 72
100 75
110 76
120 75
130 75
140 77
150 77
200 82
250 96
300 94
The volume was set at dB with white noise playing ~1 meter away on a stand. Volume was not adjusted during testing.
As you can tell the Xover design sucks at lower freq. response.
But...the speaker cabinet design ROCKS! Capable of 75 dbs at 30 Hz! That says a lot about SM and P10s design and their experience in speaker design. Even that I can hear/measure 10hz is a miracle.
Does that answer your question?
Ron
Edit: These are premium component Xovers as designed by SEAS
I will be rebuilding the Xovers when I get a few bucks to play with
rob3262 said:
Renron,
You mention the 'what if' of a larger cabinet. After listening for the last months or so, are you satisfied with the low end or would you trade some response ripple for a deeper tone if you could turn back time? I do have to say that your curved cabinets are absolutely beautiful
- Rob
Rob,
Thank you for the compliment on the speakers. They were a labor of love and I enjoy looking (and listening) to them everyday. Would I make them bigger?
Maybe.
They are quite tall in comparison to other speakers, and the tallest I could get away with, considering the WAF
. I am not a Bass hound, but I do enjoy the subtleties in the music, whether it is the squeaking fingers on the frets of a guitar, the shimmering of a symbol or the melody from the bass guitar that I never heard before.
Back to your question, I'm extremely pleased with the sound and feel it is balanced and not lacking in the bass department given the size of the mid-woofers.
Is a sub-woofer needed to fill in the bottom end when enjoying Eric Clapton or critical listening sessions? No.
Is a sub-woofer needed for HT? Absolutely, nothing beats the rumbling/shaking of the couch when the plane/car/explosion reaches it's crescendo.
A quick check with my RS (non calibrated) digital db meter says;
Hz Db
10 63
20 72
30 75
40 73
50 69
60 68
70 68
80 72
90 72
100 75
110 76
120 75
130 75
140 77
150 77
200 82
250 96
300 94
The volume was set at dB with white noise playing ~1 meter away on a stand. Volume was not adjusted during testing.
As you can tell the Xover design sucks at lower freq. response.
But...the speaker cabinet design ROCKS! Capable of 75 dbs at 30 Hz! That says a lot about SM and P10s design and their experience in speaker design. Even that I can hear/measure 10hz is a miracle.
Does that answer your question?
Ron
Edit: These are premium component Xovers as designed by SEAS
I will be rebuilding the Xovers when I get a few bucks to play with
They're a Mass Loaded Quarter Wave Resonator (ML QWR) sometimes called a Mass Loaded Transmission Line (MLTL).
The difference between an ML QWR and a reflex cabinet is that the latter assumes a uniform air-particle density throughout the cabinet, and no standing waves at all. An ML QWR deliberately generates and uses standing waves, which are resistively loaded by a restricted terminus. The light damping / lining is there to damp the line harmonic modes, which in an untapered line like this, occur at even multiples of the fundamental cabinet resonance.
Hope that helps
Scott
The difference between an ML QWR and a reflex cabinet is that the latter assumes a uniform air-particle density throughout the cabinet, and no standing waves at all. An ML QWR deliberately generates and uses standing waves, which are resistively loaded by a restricted terminus. The light damping / lining is there to damp the line harmonic modes, which in an untapered line like this, occur at even multiples of the fundamental cabinet resonance.
Hope that helps
Scott
Gotta live with what ya got thou.
Renron said:Doesn't look so good on a graph......
I may have to break into my piggy bank so I can buy the components to A/B the different Xovers.
Ron
Still, graph doesn't look good to me.?
Doing in room measurements are really hard below 200-300 Hz...and only valid for that room... and the RS meter is far from accurate, particularily the digital one (sure there are calibration cirves, but i'm pretty sure each meter needs a slightly different correction... )
besides, FR is only 1 dimension of a multi-dimensional space of speaker performance metrics (many of which we are as yet unable to measure -- or don't even know they exist)
It is the case that FR is one of the most accessible tools available to speaker designers so we often have the case of everything being treated like a nail.
dave
Scottmoose said:
Scott,
Are there predictions on how Ron's curved panels affect the standing waves (wave function?), or any cabinet design that departs from rectangular? Ron's panels taper torwards the back. What if the side panels were bowed from front to back?
I would guess that Driver placement is still dictated by the vertical dimension of the cabinet, but wonder if altering the shape of the cab means driver placement needs to be reviewed.
Cheers,
- Rob
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