If You Increase the Box Size To 6 Ft³
A 50% increase in box size will yield 40 Hz and an F3, more or less. A really well tuned box will go flat down to just above the F3, then abruptly head south. These will gradually ease down to the F3. So the F3 is 40, but the F2 is 90. By the time you get up to 200, you are about at midrange level.
This might or might not be satisfactory.
PS: Here the Kappa is tuned to 40 Hz, the Magnum tuned to 37 Hz. Just worked out a little better that way.
A 50% increase in box size will yield 40 Hz and an F3, more or less. A really well tuned box will go flat down to just above the F3, then abruptly head south. These will gradually ease down to the F3. So the F3 is 40, but the F2 is 90. By the time you get up to 200, you are about at midrange level.
This might or might not be satisfactory.
PS: Here the Kappa is tuned to 40 Hz, the Magnum tuned to 37 Hz. Just worked out a little better that way.
Attachments
>My biggest concern is that there is some negative effect due to it's emphasis on handling huge amounts of power-maybe we lose some subtlety?
====
That's usually the case in drivers designed with running flat out without burnout as the primary goal.
====
>GM: what do you think?
====
The Magnum 18LF is my pick of the litter. It has the right amount of cone damping so that no notch filter is required, with a ~max flat 40hz F3 in 120L. Ya'll can rely on room gain if you want, I prefer to build the performance in and dial it back as required, to keep distortion low.
====
>I don't know how many Bert is selling, but got the idea that he has moved the crucial minimum first order!
====
Don't have a clue, but it wouldn't surprise me. Altecs are pretty rare in Europe and what with the the cost of shipping today......
====
>That Altec seems to be revered as the best - I guess based on that model?
====
It's one of them.
====
>What were the years it was made? (just curious)
====
It was introduced in '42 and with various changes to suit the times/equipment was made till Altec closed their doors in the late '90s. The 'new' Altec has re-introduced them, but they don't own the original tooling, so I'm not hopeful of them having the same sonic signature that made them famous.
====
> In what ways does Bert's seem to match the Altec?
====
His specs are a composite of the various 515 series, but there's many drivers available with similar specs. What sets the 515 apart is its diaphragm.
====
>Maybe you are on to how to make the great driver- copy the Altec! I would imagine that this has ben tried before? It must not be easy to get right. Maybe it's just that the pro market has gone chasing power handlig rather than quality sound
====
During their heyday, they had a legal dept. that kept that from happening, and now the tooling/technology is owned by Great Plains Audio I believe, but I gather the 'new' Altec is getting tooled up in China to produce them. Whether they can figure out/measure the pulp mix and doping routine is anybody's guess.
Yeah, this is one of the many things that hurt Altec's business in the early '70s, ending their domination of the prosound/cinema market. For whatever reason they were 'too little, too late' upgrading to take advantage of the new materials technology and new wave of relatively cheap high power amps, allowing both JBL and Bose to take over.
====
>I 'm pretty sure the Altec uses an Alnico magnet, so if you believe that this is important, Eminence might still be able to come through since they still make guitar speakers with alnico.
====
All the early ones do, of course, but their later ceramic version sound fine. Mine are AlNiCo due to having been bought in the '60s, but I don't ascribe to some folks contention that they are sonically superior to the ceramic versions. They just sound better when pushed to thermal or excursion compression. Design/build the system right and this isn't an issue.
====
> I'm kinda hoping that the Neo magnets exibit the positive characteristics of alnico- based on no evidence except that they are different than ferrite.
====
The main advantage of Neo is their weight:field strength and greater field strength capability. Thing is though that you use a motor with the right amount of strength to meet the design goals. If you're trying to move a very high mass driver at high efficiency or keep the motor small, then Neo is the way to go, but otherwise......
====
>It's just that I have a 15" now and it seems to work almost like a flat panel! the movement is so small that I can't help thaink that that is why the sound is so un distorted.
====
That's a major reason......
====
>Besides, 15" are the big fad these days.....
====
Fads are for women's clothes, speaker design is about using the right drivers to meet the performance goals. I run dual 15", so I guess I'm in high style.
GM
====
That's usually the case in drivers designed with running flat out without burnout as the primary goal.
====
>GM: what do you think?
====
The Magnum 18LF is my pick of the litter. It has the right amount of cone damping so that no notch filter is required, with a ~max flat 40hz F3 in 120L. Ya'll can rely on room gain if you want, I prefer to build the performance in and dial it back as required, to keep distortion low.
====
>I don't know how many Bert is selling, but got the idea that he has moved the crucial minimum first order!
====
Don't have a clue, but it wouldn't surprise me. Altecs are pretty rare in Europe and what with the the cost of shipping today......
====
>That Altec seems to be revered as the best - I guess based on that model?
====
It's one of them.
====
>What were the years it was made? (just curious)
====
It was introduced in '42 and with various changes to suit the times/equipment was made till Altec closed their doors in the late '90s. The 'new' Altec has re-introduced them, but they don't own the original tooling, so I'm not hopeful of them having the same sonic signature that made them famous.
====
> In what ways does Bert's seem to match the Altec?
====
His specs are a composite of the various 515 series, but there's many drivers available with similar specs. What sets the 515 apart is its diaphragm.
====
>Maybe you are on to how to make the great driver- copy the Altec! I would imagine that this has ben tried before? It must not be easy to get right. Maybe it's just that the pro market has gone chasing power handlig rather than quality sound
====
During their heyday, they had a legal dept. that kept that from happening, and now the tooling/technology is owned by Great Plains Audio I believe, but I gather the 'new' Altec is getting tooled up in China to produce them. Whether they can figure out/measure the pulp mix and doping routine is anybody's guess.
Yeah, this is one of the many things that hurt Altec's business in the early '70s, ending their domination of the prosound/cinema market. For whatever reason they were 'too little, too late' upgrading to take advantage of the new materials technology and new wave of relatively cheap high power amps, allowing both JBL and Bose to take over.
====
>I 'm pretty sure the Altec uses an Alnico magnet, so if you believe that this is important, Eminence might still be able to come through since they still make guitar speakers with alnico.
====
All the early ones do, of course, but their later ceramic version sound fine. Mine are AlNiCo due to having been bought in the '60s, but I don't ascribe to some folks contention that they are sonically superior to the ceramic versions. They just sound better when pushed to thermal or excursion compression. Design/build the system right and this isn't an issue.
====
> I'm kinda hoping that the Neo magnets exibit the positive characteristics of alnico- based on no evidence except that they are different than ferrite.
====
The main advantage of Neo is their weight:field strength and greater field strength capability. Thing is though that you use a motor with the right amount of strength to meet the design goals. If you're trying to move a very high mass driver at high efficiency or keep the motor small, then Neo is the way to go, but otherwise......
====
>It's just that I have a 15" now and it seems to work almost like a flat panel! the movement is so small that I can't help thaink that that is why the sound is so un distorted.
====
That's a major reason......
====
>Besides, 15" are the big fad these days.....
====
Fads are for women's clothes, speaker design is about using the right drivers to meet the performance goals. I run dual 15", so I guess I'm in high style.
GM
Here is a very interesting selection. The McCauley 6242.
Has Thiele-Small specs which appear tailor made for a 4 Ft³ box with an F3 of 40 Hz.
Made in Washington State. Not that much buzz around here, but ran into a band whose sound man refuses to use anything but McCauleys. Searches on the internet seem to indicate a speaker generally regarded as a cut above Eminence.
Price is a cut above Eminence as well. Internet Light and Sound has them for $279, Speaker city for $338. $279 is a little higher than your spec, but not terribly so.
http://www.internetsoundandlight.com/speakers.htm
But what specs. Here is the simulation for a McCauley 6242 in a 4 Ft³ box tuned to 39 Hz. Significantly more low end than the others.
Has Thiele-Small specs which appear tailor made for a 4 Ft³ box with an F3 of 40 Hz.
Made in Washington State. Not that much buzz around here, but ran into a band whose sound man refuses to use anything but McCauleys. Searches on the internet seem to indicate a speaker generally regarded as a cut above Eminence.
Price is a cut above Eminence as well. Internet Light and Sound has them for $279, Speaker city for $338. $279 is a little higher than your spec, but not terribly so.
http://www.internetsoundandlight.com/speakers.htm
But what specs. Here is the simulation for a McCauley 6242 in a 4 Ft³ box tuned to 39 Hz. Significantly more low end than the others.
Attachments
On the issue of symmetrical field, I Emailed them the following letter:
-----Original Message-----
Sent: Tuesday, September 02, 2003 6:19 PM
To: tech@mccauley.com
Subject: 6242-symmetrical magnetic field?
Sir: I am interested in your 6242 PA speaker. Excellent Thiele-Small
specs. Plus I got a personal recommendation from a band.
On your 6242 model, do you have a symmetrical magnetic field? By which I mean an extended pole piece or a Faraday ring. We will be using these
in a ported enclosure, and in my experience if you do not have a speaker with a symmetrical magnetic field in a ported enclsoure, as you near the resonance frequency, the voice coil actually moves to the end of it's travel and tries to move and forth from there, essentially shearing off half the waveform. It is called "high second order distortion", or "suck-in".
Normally, if the manufacturer does not mention this on the website, it means that the speaker does not have a symmetrical magnetic field. However, your speakers seem to be well made, and I thought perhaps you just forgot to include it in on your website.
Also, is there any chance that you can attach a frequency response chart for the 6242 on your reply Email?
Thank you,
Kelticwizard
Okay, I didn't really sign it "Kelticwizard". But the rest is accurate.
-----Original Message-----
Sent: Tuesday, September 02, 2003 6:19 PM
To: tech@mccauley.com
Subject: 6242-symmetrical magnetic field?
Sir: I am interested in your 6242 PA speaker. Excellent Thiele-Small
specs. Plus I got a personal recommendation from a band.
On your 6242 model, do you have a symmetrical magnetic field? By which I mean an extended pole piece or a Faraday ring. We will be using these
in a ported enclosure, and in my experience if you do not have a speaker with a symmetrical magnetic field in a ported enclsoure, as you near the resonance frequency, the voice coil actually moves to the end of it's travel and tries to move and forth from there, essentially shearing off half the waveform. It is called "high second order distortion", or "suck-in".
Normally, if the manufacturer does not mention this on the website, it means that the speaker does not have a symmetrical magnetic field. However, your speakers seem to be well made, and I thought perhaps you just forgot to include it in on your website.
Also, is there any chance that you can attach a frequency response chart for the 6242 on your reply Email?
Thank you,
Kelticwizard
Okay, I didn't really sign it "Kelticwizard". But the rest is accurate.
The next business day I received the following Email from Mccauley tech support:
"All of our 6000 series drivers have "under cut" machined pole pieces, thereby creating a symmetrical flux pattern in the gap. It is usually not mentioned specifically since we have been doing this for 20 years in our magnetic assemblies.
This does reduce the amount of off-set (also known as "oil-canning") a driver experiences during large excursions and helps to maintain symmetrical excursion within the magnetic gap up to the point of Xmax. This also reduces even-order harmonic distortion, our drivers are also known foe low-levels of THD of both even and the more offensive odd orders.
Currently we do not have frequency response graphs of our raw drivers, we are in the process of re-measuring all the currently available cone drivers and this data should be available in the next few weeks.
If you have any more questions feel free to contact me at any time.
Scott Holden
Applications and Design Engineer
McCauley Sound Inc.
16607 Meridian Avenue East
Puyallup, WA 98375 USA
253.848.0363 voice
253.841.3050 fax
http://www.mccauley.com
http://www.linearray.com
scott@mccauley.com"
I really am not sure how undercutting the pole piece is supposed to prevent "suck-in", but at least the problem is being addressed. Maybe it has something to do with the cast aluminum basket-perhaps iron baskets require lengthening the pole piece, and aluminum baskets require shortening it. After all, iron can become part of the magnetic circuit. I understand that the displacement has been known to work one direction in some speakers, and the opposite in others. Perhaps this is the reason.
He says it reduces-not eliminates-the phenomenon, but also says things stay symmetrical within Xmax. Basically, I am satisfied that this company is doing something about the displacement issue. Many companies do not.
A look through the website,
http://www.mccauley.com/mainframe.htm A click through "Components" , then "15", then "6242"-reveals a well made speaker with double spiders, etc. That is why I figured they might have a symmetrical magnetic field even though they did not mention it.
"All of our 6000 series drivers have "under cut" machined pole pieces, thereby creating a symmetrical flux pattern in the gap. It is usually not mentioned specifically since we have been doing this for 20 years in our magnetic assemblies.
This does reduce the amount of off-set (also known as "oil-canning") a driver experiences during large excursions and helps to maintain symmetrical excursion within the magnetic gap up to the point of Xmax. This also reduces even-order harmonic distortion, our drivers are also known foe low-levels of THD of both even and the more offensive odd orders.
Currently we do not have frequency response graphs of our raw drivers, we are in the process of re-measuring all the currently available cone drivers and this data should be available in the next few weeks.
If you have any more questions feel free to contact me at any time.
Scott Holden
Applications and Design Engineer
McCauley Sound Inc.
16607 Meridian Avenue East
Puyallup, WA 98375 USA
253.848.0363 voice
253.841.3050 fax
http://www.mccauley.com
http://www.linearray.com
scott@mccauley.com"
I really am not sure how undercutting the pole piece is supposed to prevent "suck-in", but at least the problem is being addressed. Maybe it has something to do with the cast aluminum basket-perhaps iron baskets require lengthening the pole piece, and aluminum baskets require shortening it. After all, iron can become part of the magnetic circuit. I understand that the displacement has been known to work one direction in some speakers, and the opposite in others. Perhaps this is the reason.
He says it reduces-not eliminates-the phenomenon, but also says things stay symmetrical within Xmax. Basically, I am satisfied that this company is doing something about the displacement issue. Many companies do not.
A look through the website,
http://www.mccauley.com/mainframe.htm A click through "Components" , then "15", then "6242"-reveals a well made speaker with double spiders, etc. That is why I figured they might have a symmetrical magnetic field even though they did not mention it.
One more thing. Internet Sound And Light said that McCauleys are known for high power handling. Perhaps that means a rough frequency response-or perhaps, since these are more expensive than Eminence and others, they give you both. It would seem unfair to penalize a company because they have good power handling, I would think.
As you are on the Left Coast, I would think that McCauleys would be well known, and perhaps you can audition some 6242's and get some impressions from people there. I definitely get the impresseion they are well-known in the West, not quite so popular, (though not unknown), elsewhere.
Here are the Thiele-Small parameters:
Nominal Diameter 380 mm / 15
Rated Impedance 4 or 8 ohms
Power Capacity 800 W cont. program
Sensitivity 95 dB
Frequency Range 25 Hz - 1200 Hz
Highest Recommended X-Over 800 Hz
Recommended Enclosure Volume 85-255 L / 3-9 ft3
Effective Piston Diameter 337mm / 13.25
Voice Coil Material Edgewound copper ribbon
Voice Coil Diameter 100mm / 4"
Magnetic Coil Gap 7.5mm / 0.295
Magnetic Assembly Weight 7.7kg / 17 lbs
Flux Density 13,500 gauss
Bl Factor 23.5 T*m(8)
Moving Mass 0.146 kg
Fs Free Air Resonance 39 Hz
Re D.C. Coil Resistance 3.2(4) 6.0(8) ohms
Qts Total Quality Factor 0.40
Qms Mechanical Losses 10.5
Qes Electrical Losses 0.41
Vas Equivalent Volume of Air 116 L / 4.10 ft3
Sd Effective Piston Area .089 m2 / 136 in2
Xmax Excursion - Max Bl 8.4 mm / 0.33
Vd Sd x Xmax 750 cm3 / 66 in3
Le Inductance of V.C. . 0.8 mH (4) 1.6 mH(8)
%eff Mid Band Effeciency 1.9%
Pe Max Power Rating 400 W RMS sine wave
Overall Diameter 390 mm / 15.35
Overall Depth 142 mm / 5.6
Bolt Circle Diameter 372 mm / 14.65
Baffle Cutout Diameter
Front Mount 355 mm / 13.97
Rear Mount . 47 mm / 13.65
Net Weight 10.6 kg / 23.5 lbs
As you are on the Left Coast, I would think that McCauleys would be well known, and perhaps you can audition some 6242's and get some impressions from people there. I definitely get the impresseion they are well-known in the West, not quite so popular, (though not unknown), elsewhere.
Here are the Thiele-Small parameters:
Nominal Diameter 380 mm / 15
Rated Impedance 4 or 8 ohms
Power Capacity 800 W cont. program
Sensitivity 95 dB
Frequency Range 25 Hz - 1200 Hz
Highest Recommended X-Over 800 Hz
Recommended Enclosure Volume 85-255 L / 3-9 ft3
Effective Piston Diameter 337mm / 13.25
Voice Coil Material Edgewound copper ribbon
Voice Coil Diameter 100mm / 4"
Magnetic Coil Gap 7.5mm / 0.295
Magnetic Assembly Weight 7.7kg / 17 lbs
Flux Density 13,500 gauss
Bl Factor 23.5 T*m(8)
Moving Mass 0.146 kg
Fs Free Air Resonance 39 Hz
Re D.C. Coil Resistance 3.2(4) 6.0(8) ohms
Qts Total Quality Factor 0.40
Qms Mechanical Losses 10.5
Qes Electrical Losses 0.41
Vas Equivalent Volume of Air 116 L / 4.10 ft3
Sd Effective Piston Area .089 m2 / 136 in2
Xmax Excursion - Max Bl 8.4 mm / 0.33
Vd Sd x Xmax 750 cm3 / 66 in3
Le Inductance of V.C. . 0.8 mH (4) 1.6 mH(8)
%eff Mid Band Effeciency 1.9%
Pe Max Power Rating 400 W RMS sine wave
Overall Diameter 390 mm / 15.35
Overall Depth 142 mm / 5.6
Bolt Circle Diameter 372 mm / 14.65
Baffle Cutout Diameter
Front Mount 355 mm / 13.97
Rear Mount . 47 mm / 13.65
Net Weight 10.6 kg / 23.5 lbs
Since we are dredging up every pro driver maker (a good thing!):
A Japanese tube amp company has plans for speakers using these drivers. I've heard of others that use them too.
I'm still trying to track them down
Anyone know about these guys?
http://www.radianaudio.com/
These guys make 24" woofers:
http://www.papl.co.uk/asps/ShowDetails.asp?id=17
A Japanese tube amp company has plans for speakers using these drivers. I've heard of others that use them too.
I'm still trying to track them down
Anyone know about these guys?
http://www.radianaudio.com/
These guys make 24" woofers:
http://www.papl.co.uk/asps/ShowDetails.asp?id=17
I've not tried the 15", but I'm impressed by the Radian's that I've used.
http://www.ampslab.com/speakers2.htm
http://www.ampslab.com/speakers2.htm
Yes, Yes, Yes!!! Ampslab, you were the ones I was remembering. Apologies for getting the country wrong 
DIY Audio comes through again!!
There is another speaker company also that uses Radian.
I think just the co-ax. I remember that they cost a lot but had beautiful cabinets andwere in the USA -do you know of them?
The Radian compression drivers use an aluminum diaphram and special suspension, which is supposed to be better damped than titanium.
DIY Audio comes through again!!
There is another speaker company also that uses Radian.
I think just the co-ax. I remember that they cost a lot but had beautiful cabinets andwere in the USA -do you know of them?
The Radian compression drivers use an aluminum diaphram and special suspension, which is supposed to be better damped than titanium.
No apologies required. It was recently reported in our largest national english newspaper that one of our most progressive discos called Zouk is very well known internationally, yet many thought Singapore is somewhere in China. Someone in the Singapore Tourist Promotion Board is not doing his job.
The Radian co-ax in those beautiful cabinets, if they are black, piano gloss finish, could well be a friend of mine who is now residing in LA. He was kind enough to introduce the Radians to me.
You are right about the Radian compression drivers. Very sweet. Their LF drivers are also very well designed, match well with their comp drv. Properly loaded, their LF drivers are capable of producing the bass that I prefer ---- dynamic yet define. All these come with a price. The Radians are far more expensive than say Vifa. Apologies for going off topic.
Someone in the Singapore Tourist Promotion Board is not doing his job.The Radian co-ax in those beautiful cabinets, if they are black, piano gloss finish, could well be a friend of mine who is now residing in LA. He was kind enough to introduce the Radians to me.
You are right about the Radian compression drivers. Very sweet. Their LF drivers are also very well designed, match well with their comp drv. Properly loaded, their LF drivers are capable of producing the bass that I prefer ---- dynamic yet define. All these come with a price. The Radians are far more expensive than say Vifa. Apologies for going off topic.
I sent an email to Radian. When they respond, I will hit them with the symetrical question, and what the pricing is like. The webpage doesn't address the symetrical issue. The USA speaker brand that uses the 8" co-ax (ceiling) driver cost over $3000 a pair. I assumed another overpriced upscale product- now I'm scared - those drivers might be pricey.
Anyway MCP, you actually are on topic, I say so, and I'm the thread starter I'm interested in any efficient pro type drivers that sound great.
Earlier I let someone discuss 18" drivers for God's sake
Anyway MCP, you actually are on topic, I say so, and I'm the thread starter
I'm interested in any efficient pro type drivers that sound great. Earlier I let someone discuss 18" drivers for God's sake
Charles:
I am not that familiar with T shaped pole pieces, though I have heard of them often. Is that the same as T shaped yoke?
What else have you heard about McCauleys?
Yes, that ± 16 mm is quite phenomenal for a PA driver. I am about to Emaiol them to ask if the excursion they list are ± or peak-to-peak. PA drivers especially have a habit of listing excursion as peak-to-peak.
They already give us the magnetic gap height. I wish they would give us the voice coil winding length as well. A lot of PA speakers leave that out.
I am not that familiar with T shaped pole pieces, though I have heard of them often. Is that the same as T shaped yoke?
What else have you heard about McCauleys?
Yes, that ± 16 mm is quite phenomenal for a PA driver. I am about to Emaiol them to ask if the excursion they list are ± or peak-to-peak. PA drivers especially have a habit of listing excursion as peak-to-peak.
They already give us the magnetic gap height. I wish they would give us the voice coil winding length as well. A lot of PA speakers leave that out.
It's quite a long time I have visited their website fort the last time. But back then they were quite exact regarding the definitions of excursion; i.e. they clearly distinguished between linear excursion and max excursion before damage.
My interest was triggered by a test in a German DIY speaker mag so I visited their website.
They had very interesting coaxial drivers that I intended to use for a bass-instruments box (2*10" with one driver being coaxial like some of the BagEnd ones). Back then they were not very responsive to e-mail so I gave up on them, although the products themselves were veeeeeery interesting.
Regading the T-shaped polepiece: You have a pole piece that is narrower by some degree behind the gap. This way you create a more homogenuous field.
Regards
Charles
My interest was triggered by a test in a German DIY speaker mag so I visited their website.
They had very interesting coaxial drivers that I intended to use for a bass-instruments box (2*10" with one driver being coaxial like some of the BagEnd ones). Back then they were not very responsive to e-mail so I gave up on them, although the products themselves were veeeeeery interesting.
Regading the T-shaped polepiece: You have a pole piece that is narrower by some degree behind the gap. This way you create a more homogenuous field.
Regards
Charles
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