Beyond the Ariel

[Salas]

I think where people go astray is thinking the waves from the individual point-source radiators somehow combine into a cylindrical wavefront - but they don't. They pass right through each other. True, at the very lowest frequencies (comparable to the size of the array), there is mutual coupling and a resulting increase in efficiency, but this falls apart as the wavelengths become shorter. What starts out as an efficient loudspeaker at the lowest frequencies become dominated by comb-filtering and time-dispersal at higher frequencies - and these are errors that are degraded by equalization, since EQ spreads out the time-dispersal even more.

The best model for thinking about what a tall line array does, is to conceive it as an infinite Bessel array IMHO.

 

[SunRa]

Hello Lynn,

This driver here seems to fit in your requeirments of a frequency graphic with a variation of less than 5dB. However the spl isn't very high (arround 96dB), and the rest of the thiel-small parameters are missing.

 

[Variac]

It was mentioned further up this page:
http://www.diyaudio.com/forums/showthread.php?postid=1482407#post1482407


For my speakers it might be perfect and I would be interested in hearing from anyone who has tried it. My speakers are Basszilla's and have the bass driver in a reflex box and a ribbon tweeter. I currently use the Fosex 208EZ for the 8" open baffle midmid.
Troels has a nice essay here:

http://www.troelsgravesen.dk/HES.htm

Parts Express sells Jantzen in the US but they don't list that driver. I'll bet that they can order it!! Any reports from people that have heard it?

I think that probably you are right- Lynn probably wants more efficiency. But it isn't bad... flat respose and they claim, few spikes in response..

 

[Anglo]

845 SET amplifiers have very serious issues with driver-tube distortion. The distortion of the 845 is very low, in the 300B league, but the 120~150 volt bias demands drive voltages twice as large as the 300B, and there's just as much Miller capacitance as a 300B. In other words, a difficult-to-drive, highly reactive load at higher frequencies (potential slewing problems).

This a creates a requirement for a driver section with less distortion than the output tube at grid-drive levels around 200V rms - a small, ultralow distortion Class A power amplifier in its own right. No known RC-coupled driver can accomplish this due to the slope of the load-line and power losses in the plate-load resistor. Choke, transformer, or dynamic loads can do this, but only DHT's achieve the requisite low distortion levels - and it seems pointless to use a low-distortion output tube if the driver distortion swamps it out.

So-called distortion-cancellation schemes using driver tubes with complementary distortion to the output do not account for the upper harmonics, which are the ones that really matter. (2nd harmonic dominates THD measurements but is nearly inaudible. The magnitudes of the upper harmonics - 3rd, 4th, 5th, etc. - are much smaller but are also much more noticeable.)

If you like the sound of the 845 (SE or PP), seek out a design that uses a DHT driver and choke, transformer, or active loads for the driver. No RC-coupling, sorry. It's easy and cheap to do but has 3~5 times the driver-tube distortion, not a small difference. That probably eliminates most commercial 845 amplifiers, and many DIY designs. [/B]

Ouch!

I have 2 monoblock SETs done by a guy in our neck of the woods i.e DIY. How he did them exactly, I dunno. I know didly squat on amps. My interest ahs always been speakers...

My EVs are fed by the SETs only and are run fullrange. See it as you will, but very few amps, even though they state 103db efficiency at 1Khz, have been able to make these beasts sing. A lot of amps I have tried weren't up to the task. The only 2 that did it well, have been a Plinius SS and these tube amps. Still, I remain curious to hear other opportunities.

I'd sure like to hear your amps, however the distance isn't in my favour!

 

[LineSource]

Acoustic Elegance Speakers were mentioned earlier, these T/S parameters for their promised Lambda designs were just posted in their forums.

The TD10M or TD12M could be canidates for a wide bandwidth midrange between the double high RAAL ribbon and the 15"-18" bass dipole.


TD15M - 8ohm
Fs: 34.7Hz
Qms: 5.09
Vas: 312L
Cms: .3mm/N
Mms: 70g
Rms: 3kg/s
Xmax: 6mm
Sd: 855
Qes: .35
Re: 6.6
Le: .2mH
Z: 8ohm
Bl: 17Tm
Pe: 500W
Qts: .33
1W SPL: 97.8dB

TD15H- 8ohm
Fs 21.0 Hz
Qms 4.23
Qes 0.27
Qts 0.26
Vas 467 Liters
Cms 0.45 mm/N
Mms 129 grams
Sd 855 cm2
Rms 4.0 Kg/S
Bl 20.1 T/m
Re 6.5 ohms
Z 8ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
"no" 1.51 %
1WSpl 94.0 dB
Linear Xmax 14 mm (peak)
Mech Xsus 20 mm (peak)

TD15X- 8ohm
Fs 23.2 Hz
Qms 3.82
Qes 0.31
Qts 0.28
Vas 467 Liters
Cms 0.45 mm/N
Mms 105 grams
Sd 855 cm2
Rms 4.0 Kg/S
Bl 16.7 T/m
Re 5.6 ohms
Z 8 ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
"no" 1.82 %
1WSpl 94.8 dB
Linear Xmax 14 mm (peak)
Mech Xsus 20 mm (peak)

TD15S- 8ohm
Fs 22.8 Hz
Qms 3.87
Qes 0.41
Qts 0.37
Vas 467 Liters
Cms 0.45 mm/N
Mms 108 grams
Sd 855 cm2
Rms 4.0 Kg/S
Bl 14.1 T/m
Re 5.3 ohms
Z 8 ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
"no" 1.31 %
1WSpl 93.4 dB
Linear Xmax 14 mm (peak)
Mech Xsus 20 mm (peak)


TD10M - 8ohm
Fs: 40.5Hz
Qms: 2.7
Vas: 59L
Cms: .35mm/N
Mms: 44g
Rms: 4kg/s
Xmax: 6mm
Sd: 345
Qes: .26
Re: 6.6
Le: .2mH
Z: 8ohm
Bl: 17Tm
Pe: 500W
Qts: .23
1W SPL: 93.9dB

TD10H- 8ohm
Fs; 27.6 Hz
Qms: 4.88
Qes: 0.23
Qts: 0.22
Vas: 68 Liters
Cms: 0.4 mm/N
Mms: 83 grams
Sd: 345 cm2
Rms: 3.0 Kg/S
Bl: 20.4 T/m
Re: 6.5 ohms
Z 8ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
1WSpl: 90.1 dB
Linear Xmax: 14 mm (peak)
Mech Xsus: 18 mm (peak)

TD10X- 8ohm
Fs: 35.5 Hz
Qms: 4.22
Qes: 0.29
Qts: 0.27
Vas: 67.5 Liters
Cms: 0.4 mm/N
Mms: 50 grams
Sd: 345 cm2
Rms: 2.7 Kg/S
Bl: 16.7 T/m
Re: 7.2 ohms
Z: 8 ohms
Le: 0.3 mH
Pe (max): 500 Watts
Pe (transient): 1000 Watts
1WSpl 92 dB
Linear Xmax 14 mm (peak)
Mech Xsus 18 mm (peak)

TD10S- 8ohm
Fs: 32.7 Hz
Qms 3.04
Qes 0.39
Qts 0.34
Vas 68 Liters
Cms 0.4 mm/N
Mms 59.4 grams
Sd 345 cm2
Rms 4.0 Kg/S
Bl 13.1 T/m
Re 5.5 ohms
Z 8 ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
1WSpl 90 dB
Linear Xmax 14 mm (peak)
Mech Xsus 18 mm (peak)

IB Infinite Baffle Woofers
Fs: 16Hz
Qms: 6.8
Vas: 439L
Cms: .45mm/N
Mms: 220g
Rms: 3.239
Xmax: 18.5mm
Xmech: 25mm
Sd: 830sqcm
Vd: 3.07L (p-p)
Qes: .78
Re: 5.5ohm
Le: .33mH
Bl:12.49
Pe: 500W
Qts: .7
1WSPL: 86dB
2.83V: 87.3dB

Physical dimensions:
Cutout hole: 14"
Outer diameter: 15.5"
Mounting Depth: 7.5"
Overall Depth: 8"

$129 each or 4 for $400

 

[augerpro]

Have full TSPs for the Dipole15 been released?

 

[LineSource]

Have full TSPs for the Dipole15 been released?

T/S specs for the original Lambda 15" dipoles. The speaker uses an underhung motor which provides low distortion within the spec X-max, but distortion increases rapidly when the cone moves beyond x-max.

Fs 21.66Hz
Vas 623L
Qms 15.16
Qes 1.002
Qts 0.94
Re 12.3 ohms
Impedance 16 ohms
Bl 12.26Tm
Mms 90g
Le 0.3mH
1Wspl90dB
xmax 13mm peak
voice coil height 12.4mm
air gap 38.4mm
Sd 855cm2
Pmax ~100W

 

[John_E_Janowitz]

The TD10M or TD12M could be canidates for a wide bandwidth midrange between the double high RAAL ribbon and the 15"-18" bass dipole.

I have actually been talking with Alex at RAAL recently about using some if his drivers and him possibly using some of ours. This is really a combination of the ultimate in woofer/midbass and the ultimate in ribbon tweeters.

Regarding the TDM drivers out of all of them, the 15" has the best response both on and off axis. It uses a curvilinear cone profile from an old altec driver. This profile really makes the difference as it is very flat to over 4KHz on axis and to 2KHz at about 30 degrees off axis. There is no resonance from the dustcap which is a large issue in many drivers. The cone and surround are both hand treated and have nearly no resonance of their own. It is quite flat electrically up to 5KHz or higher. Notice the .3mH inductance is lower than many 6.5" drivers. Here is an impedance curve of the driver.

An externally hosted image should be here but it was not working when we last tested it.

We actually use this driver in many bass guitar cabinets played full range with no need for a tweeter to supplement the high end. Response is quite good up to 10KHz. Of course you have quite a narrow beam at those ranges, but when putting a mic in front you dont' need more of a range.

I will try to get some decent response curves soon. For now all I have is with a pair of TD15M's in an MTM configuration with the BMS 1.4" coax compression driver on an 18sound XT1464 horn between. It is not fully representative of a single driver as the dips at 5KHz and 10KHz are from comb effects. However it does give a good idea of the extension coming from these 15" drivers.

If you were going to do any single driver mated to a RAAL, I'd go with this 15". Much more displacement means the driver will have less excursion for any given output level and the on and off axis response is much better.

John

 

[John_E_Janowitz]

T/S specs for the original Lambda 15" dipoles. The speaker uses an underhung motor which provides low distortion within the spec X-max, but distortion increases rapidly when the cone moves beyond x-max.

With any underhung design your design goal should be to keep the driver within xmax. That way this won't be an issue. Also as an underhung design, the power handling is significantly lower than with the other TD drivers. The coil is only .5" long. Inductance though is on line with many tweeters at .0375mH with the 8ohm coils in parallel. In general though at 12mm Xmax, this driver has much more displacement available than most of the prosound drivers.

John

 

[Magnetar]

I have actually been talking with Alex at RAAL recently about using some if his drivers and him possibly using some of ours. This is really a combination of the ultimate in woofer/midbass and the ultimate in ribbon tweeters.

Regarding the TDM drivers out of all of them, the 15" has the best response both on and off axis. It uses a curvilinear cone profile from an old altec driver. This profile really makes the difference as it is very flat to over 4KHz on axis and to 2KHz at about 30 degrees off axis. There is no resonance from the dustcap which is a large issue in many drivers. The cone and surround are both hand treated and have nearly no resonance of their own. It is quite flat electrically up to 5KHz or higher. Notice the .3mH inductance is lower than many 6.5" drivers. Here is an impedance curve of the driver.

An externally hosted image should be here but it was not working when we last tested it.

We actually use this driver in many bass guitar cabinets played full range with no need for a tweeter to supplement the high end. Response is quite good up to 10KHz. Of course you have quite a narrow beam at those ranges, but when putting a mic in front you dont' need more of a range.

I will try to get some decent response curves soon. For now all I have is with a pair of TD15M's in an MTM configuration with the BMS 1.4" coax compression driver on an 18sound XT1464 horn between. It is not fully representative of a single driver as the dips at 5KHz and 10KHz are from comb effects. However it does give a good idea of the extension coming from these 15" drivers.

If you were going to do any single driver mated to a RAAL, I'd go with this 15". Much more displacement means the driver will have less excursion for any given output level and the on and off axis response is much better.

John

Why would you recommend crossing a narrow radiation ( ihave plenty of Altec 15 curvalinear cones here - they work best no higher than 1.2K with a wide radiation horn) 15" driver to a wide radiation ribbon tweeter? To me that would be a disaster. IE I found a 6" driver to be much more appropriate with a ribbon.., even when use a big ribbon as low as 1K with a 8th order network a ten inch was pushing it.

 

[John_E_Janowitz]

Why would you recommend crossing a narrow radiation ( ihave plenty of Altec 15 curvalinear cones here - they work best no higher than 1.2K with a wide radiation horn) 15" driver to a wide radiation ribbon tweeter? To me that would be a disaster. IE I found a 6" driver to be much more appropriate with a ribbon.., even when use a big ribbon as low as 1K with a 8th order network a ten inch was pushing it.

There are several things to look at and always tradeoffs. The radiation pattern is one issue, low distortion at higher SPL is another. First you need to determine the range you are covering both in frequency and the radiation pattern. If you are looking to cover only a short midrange band, then the 6" driver could be fine if SPL requirements are not too high. However if you are essentially looking to cover a large range, say from 50Hz up to the xover point, the 6" driver will just not be able to do this well at any reasonable SPL's. You will be severely limited in output with only the 6" driver and will have to deal with much higher distortions. This means you would then need a 3way system leading to more complexity in the design, more cost, etc.

The other tradeoff is to deal with the more narrow radiation pattern on the woofer that can provide these SPL's at low distortion. You would have approximately a 60degree pattern at 2KHz with the 15" TD drivers. For most applications I actually like to have a more narrow radiation pattern to minimize room interaction. It all depends on what your goals are though. If your goal is for very wide horizontal dispersion, an array of multiple smaller drivers would likely be an option, but then you would have the limited vertical dispersion and other issues with an array.

As far as the Altec drivers go, there is no way to do a direct comparison simply if they use the same profile on the cone. None of the altec drivers that I am aware of take advantage of a full copper sleeve to lower inductance. They are not close to electrically flat to the 5KHz range. Nor do they have the large phase plug which also greatly increases the usable frequency range both on and off axis.

John

 

[Magnetar]

There are several things to look at and always tradeoffs. The radiation pattern is one issue, low distortion at higher SPL is another. First you need to determine the range you are covering both in frequency and the radiation pattern. If you are looking to cover only a short midrange band, then the 6" driver could be fine if SPL requirements are not too high. However if you are essentially looking to cover a large range, say from 50Hz up to the xover point, the 6" driver will just not be able to do this well at any reasonable SPL's. You will be severely limited in output with only the 6" driver and will have to deal with much higher distortions. This means you would then need a 3way system leading to more complexity in the design, more cost, etc.

The other tradeoff is to deal with the more narrow radiation pattern on the woofer that can provide these SPL's at low distortion. You would have approximately a 60degree pattern at 2KHz with the 15" TD drivers. For most applications I actually like to have a more narrow radiation pattern to minimize room interaction. It all depends on what your goals are though. If your goal is for very wide horizontal dispersion, an array of multiple smaller drivers would likely be an option, but then you would have the limited vertical dispersion and other issues with an array.

As far as the Altec drivers go, there is no way to do a direct comparison simply if they use the same profile on the cone. None of the altec drivers that I am aware of take advantage of a full copper sleeve to lower inductance. They are not close to electrically flat to the 5KHz range. Nor do they have the large phase plug which also greatly increases the usable frequency range both on and off axis.

John

You didn't answer my question, maybe because you fail to realize the rediation of the rall ribbon at 2k?

 

[John_E_Janowitz]

You didn't answer my question, maybe because you fail to realize the rediation of the rall ribbon at 2k?

Well looking at the horizontal dispersion spl vs frequency I see nothing past 60degree on the chart. I don't have more info than that so all i can guess is that it drops slightly at 140 vs 120 degrees. I also realize that the TD15M would be only at 60 degrees. This does not mean that things completely disappear after 60degrees. You would likely have a dip in the power response the farther you go off axis. This may or may not be an issue depending on your listening position, position of speakers in room, and the room itself. If a smooth power response is your only goal, then this would not likely be the combination for you. If you can live with some differences in power response and are looking for high SPL with low distortion, it has some promise.

John

 

[Magnetar]

Well looking at the horizontal dispersion spl vs frequency I see nothing past 60degree on the chart. I don't have more info than that so all i can guess is that it drops slightly at 140 vs 120 degrees. I also realize that the TD15M would be only at 60 degrees. This does not mean that things completely disappear after 60degrees. You would likely have a dip in the power response the farther you go off axis. This may or may not be an issue depending on your listening position, position of speakers in room, and the room itself. If a smooth power response is your only goal, then this would not likely be the combination for you. If you can live with some differences in power response and are looking for high SPL with low distortion, it has some promise.

John

I wouldn't use a ribbon (I'd use a horn that would mate with it) at all, but if I did use the rall it would be mated with an appropriate driver. not a 15 - If I was concerned about SPL I would not use a ribbon but a horn, and I don't think a single 15 (any!) on an open baffle would 'cut it' IE - keep up with a good horn with 'low distortion'

The rall driver is only 3-4 db down at 15K at 60 degrees after the foam band aid is applied.

 

[augerpro]

You didn't answer my question, maybe because you fail to realize the rediation of the rall ribbon at 2k?

John is being very cordial and helpful. Please don't be rude.

 

[moray james]

thank you for your post edit ...

I only see a civil disagreement so far. We cannot like everybody and not everyone will like us so to discuss openly like this is good. Differing opinion is useful.

 

[Magnetar]

John is being very cordial and helpful. Please don't be rude.

What?

You HAVE TO BE KIDDING!

I suppose you use one of his 15's on an open baffle crossed over to a little ribbon?

 

[moray james]

There were a boat load...

of speaker designs over the decades that used a small tweeter (one inch dome to 3 inch cone) crossed over to 10 - 12 inch drivers. I always shook my head but the popularity was and still is astounding.
What about the trick of extending a ribbon to match the ribbon's vertical dimension (and polar pattern) to that of the bass driver. What happens at crossover in this situation as far as dispertion of the two drivers? Have good fudge jobs been done this way?

 

[augerpro]

What?

You HAVE TO BE KIDDING!

I suppose you use one of his 15's on an open baffle crossed over to a little ribbon?

I just stumbled onto John's creations a week ago, so no...

I don't mean to start a fight and maybe I overreacted, but very often the helpful experience you have is overshadowed by the somewhat condescending and rude manner...and the debate tends to go to hell after that. I hope you take that as a constructive observation.

I'm going to butt out now so we don't derail this thread.

 

[chrismercurio]

Earl Geddes

does it with a 15" and a compression driver.....and so does JBL.....and TAD.....and (insert professional monitor company here).

It may not be a ribbon, but the idea is what your design goals are for a system....not when one starts to beam, or how low it will go. I have heard that tweeter crossed quite low in a PA style 2-way at HIGH volumes and it is IMPRESSIVE.

Best,

C

p.s. This is Lynn's thread. Can everyone (including me) play nice in his sandbox? The mod's are on it around here when things get out of line.