[Daygloworange]

I've worked with the planars in question and know what they are capable of. I'm just trying to help someone avoid buying the wrong drivers to use with them.

No, it's a thinly veiled attempt to bash. Your intent is to claim it's a misconception that you can cross over to a planar at a low frequency, and that it is a mistake.

He was refering specifically to the driver that the original poster asked about, not to any other.

Denny, your attempts here to goad Rick are noted, and not appreciated. If you continue with this, your account will be disabled.

John,

What I'm not quite clear on, is how I'm the one being singled out as an aggressor. My feeling is that my posts usually originate from a constructive, rather than deconstructive position.

This all started with a member posting looking for guidance and technical information on a DIY line array. AudioCircle members look for correct knowledge and guidance.

As I read back the entire thread, I see my first post responding to encourage the OP to do some more investigation after other's have given opinions. I also simply stated (without quoting anyone) that I didn't agree with Rick (who mentions BG planars) empirically stating it is a misconception and a mistake that you can use a low crossover point with planars, and gave some examples of BG planars that were indeed crossed much lower than even the OP was originally intending.

I also quote the OP, and assure him that it is possible with the right woofer, to get extension into the 20's in a line array.

Up until that point in the thread, I see no wrong done.

A few posts later, Rick Craig quotes my entire post, claims I misquoted him, states empirically that I am wrong on how low you can cross planars, and that my claims of being able to get extension to the 20's is misleading and utter BS.

When I respond to being called wrong, misleading, and full of utter BS, I suddenly find myself on the chopping block.

Am I not allowed to challenge being painted as a fraud and defend myself to being labelled as wrong, misleading, and full of utter BS by another AudioCircle member and industry professional?

And how does it serve audiophiles and AudioCircle to have an AudioCircle Industry Professional member categorically state that something that is commercially proven, reviewed and endorsed by audio industry professionals and AudioCircle members, not be physically possible and to say these people are full of utter BS without a mere mention?

Cheers

[jholtz]

I've chuckled a lot while reading this thread. I've built dozens of speakers designed by Rick, Dennis Murphy, Jon Marsh and Curt Campbell. I am friends with and respect them all. They all share one common trait in speaker design, they follow the laws of physics. I profess to NOT be a crossover guru but there are some elementary basics that you learn immediately if you do any DIY speaker building. Call it crossover design 101 if you will. It is very apparent that while Rick is trying to talk about the technical aspect of the OP question, the responses to his posts are fanboys who do not understand crossover design.

Whether you have one driver or 100, the the low frequency or F3 point does NOT go lower. Multiple drivers increase the SPL output by 6 DB every time you connect two drivers in parallel but it cuts the impedance in half. Connect them in series and it doubles the impedance but doesn't increase the SPL. F3 remains the same. That is basic physics. So, if you have a driver that has a F3 of 60 Hz. for example and you want to get output from that driver at 20 Hz. you would have to reduce the output to the corresponding level that driver would be at if measured at 20 Hz. The xmax of the driver comes into question because it takes a LOT of xmax to achieve low frequencies at any volume.
So, you take multiple drivers and wire them to increase SPL while still maintaining decent impedance and then reduce the upper output of the woofers frequency response to level it to the point where there is 20 Hz. output. 

Here are the questions. Since this is so simple, why doesn't everyone in the speaker business do that? It's easy to do with an active crossover but when a passive crossover is involved, physics rears it's ugly head. Since I'm not a crossover designer, here's my suggestion. Since many of you think Rick is biased, post this question on the PE board or in the Mission Possible section of the HT Guide. Simply ask why it's not a good idea to reduce the output of the woofer circuit in a passive crossover to lower the F3.

Regarding BG and Dayton drivers. They are vastly different. The only thing they share in common is that they're planar drivers. The Neo8 is essentially comparable to a 2" mid dome in frequency response and are best used as a mid range rather than a tweeter. The response can be reduced to extend the top end extension at the sacrifice of sensitivity. The Dayton will not tolerant low crossover points. It wasn't designed for it. It's a drive that will sound much better with a 3K or higher crossover than a 2K.

This is all simple physics as it relates to speaker design. I respectfully suggest that the folks that want to argue crossover and driver merits invest in some of the speaker design books so they'll understand how it all works and can offer intelligent responses.

Best regards,

Jim

[Chops]

I've chuckled a lot while reading this thread. I've built dozens of speakers designed by Rick, Dennis Murphy, Jon Marsh and Curt Campbell. I am friends with and respect them all. They all share one common trait in speaker design, they follow the laws of physics. I profess to NOT be a crossover guru but there are some elementary basics that you learn immediately if you do any DIY speaker building. Call it crossover design 101 if you will. It is very apparent that while Rick is trying to talk about the technical aspect of the OP question, the responses to his posts are fanboys who do not understand crossover design.

Whether you have one driver or 100, the the low frequency or F3 point does NOT go lower. Multiple drivers increase the SPL output by 6 DB every time you connect two drivers in parallel but it cuts the impedance in half. Connect them in series and it doubles the impedance but doesn't increase the SPL. F3 remains the same. That is basic physics. So, if you have a driver that has a F3 of 60 Hz. for example and you want to get output from that driver at 20 Hz. you would have to reduce the output to the corresponding level that driver would be at if measured at 20 Hz. The xmax of the driver comes into question because it takes a LOT of xmax to achieve low frequencies at any volume.
So, you take multiple drivers and wire them to increase SPL while still maintaining decent impedance and then reduce the upper output of the woofers frequency response to level it to the point where there is 20 Hz. output. 

Here are the questions. Since this is so simple, why doesn't everyone in the speaker business do that? It's easy to do with an active crossover but when a passive crossover is involved, physics rears it's ugly head. Since I'm not a crossover designer, here's my suggestion. Since many of you think Rick is biased, post this question on the PE board or in the Mission Possible section of the HT Guide. Simply ask why it's not a good idea to reduce the output of the woofer circuit in a passive crossover to lower the F3.

Regarding BG and Dayton drivers. They are vastly different. The only thing they share in common is that they're planar drivers. The Neo8 is essentially comparable to a 2" mid dome in frequency response and are best used as a mid range rather than a tweeter. The response can be reduced to extend the top end extension at the sacrifice of sensitivity. The Dayton will not tolerant low crossover points. It wasn't designed for it. It's a drive that will sound much better with a 3K or higher crossover than a 2K.

This is all simple physics as it relates to speaker design. I respectfully suggest that the folks that want to argue crossover and driver merits invest in some of the speaker design books so they'll understand how it all works and can offer intelligent responses.

Best regards,

Jim

Well like I said earlier, I understand the whole thing about the xover point and the F3 of the driver. I just wasn't thinking straight when I wrote the part about lowering the xover freq with more Dayton planars. For me, that matter is now moot.

As for my MLA plans, they have been revised once again. I am going to drop the center channel for now and just focus on the main channels, and for that I am going to up the amount of drivers for this project. In my last post, I said I was going to get (20) GR M-130's and (15) Dayton PT2C-8's. That has now changed and I am going to get (24) M-130's and (16) PT2C-8's. That will give me 12 woofers and 8 planars per channel. People have been telling me that I may be able to forgo having a center channel altogether due to the imaging and large sweet spot that LA's produce. So I figured, what the heck, I'll try it this way. If anything, I can always build a matching center channel later on down the road if I want to.

Before I can do any of this however, I need to get my current speakers sold as well as my old DLP projector so I can fund this new project. 

[Rick Craig]

The same acoustic principles apply to the low frequency extension for 1 or 100 woofers. Making a claim that a 6-7" woofer in a 2-way array will have 20's extension comparable to say a 10" or 12" driver is misleading and utter BS.

Apparently not according to owners and reviewers of the GR LS-6, reporting in-room measurements down into the high teens.

The in-room measurements that have been quoted don't accurately reflect the true bass extension of the woofers. The only way to do a fair and accurate comparison is to do a nearfield test that correctly sums the output of the port and woofer. You can also do this with the crossover in place as well to note any differences caused by the filter's interaction with the woofer.

Room gain will add some to the extension of the woofer but every room is different so to state those numbers without also including nearfield / anechoic measurements is meaningless. There's also more room for error with an array because the multiple woofers will give you "optimistic" bass extension numbers with 1/3 octave pink noise.

That's not to say that multiple woofers won't give you a good listening experience; in fact, moving a great deal of air at 60hz can be impressive. But those woofers won't give you the same bottom end extension that a larger driver will unless you add a massive amount of active equalization.

[Rick Craig]

This is really interesting....

The amount of drivers has no bearing on how low a planar should be crossed. The resonance is the same regardless whether you have 1 or 100 of them and the resulting distortion will help define the best place to cross them.

Really??  The amount of drivers used has no bearing on crossover point and how far down in output the distortion is? Are you kidding me?   

The same acoustic principles apply to the low frequency extension for 1 or 100 woofers.

Really??  Physics tells us that even a 3" driver will play (say) 20 Hz. It will do so with less distortion than a large woofer. It just won't have any output because it's not displacing enough air through surface area and excursion. Add 100 of those same 3" drivers, you add surface area, without having to increase excursion (keeping distortion low), and suddenly you are increasing the output at 20 Hz.

I call that adding low frequency extension . By increasing the number of drivers, you have more surface area, therefore more output at any given frequency. It's not even rocket science.

You missquoted me.

I fail to see where.

I've worked with the planars in question and know what they are capable of. I'm just trying to help someone avoid buying the wrong drivers to use with them.

No, it's a thinly veiled attempt to bash. Your intent is to claim it's a misconception that you can cross over to a planar at a low frequency, and that it is a mistake.

Making a claim that a 6-7" woofer in a 2-way array will have 20's extension comparable to say a 10" or 12" driver is misleading and utter BS.

Really??  How many 6" or 7" woofers would it take to equal the surface area of a 10" or 12" woofer?

We've been over this:

http://www.audiocircle.com/index.php?topic=45051.20

Rick, you've clearly got LS-6 and LS-9 envy. You call what it is capable of, utter BS.

I can't believe you'd actually post that.   If I were you, I would merely say that you don't think it's possible. That way you'd have some wiggle room. Now you don't.

You claim it's not possible to get extension into the 20's with a 6" or 7" woofer.

That would make Danny a fraud, and all the experienced audiophiles who have heard the speaker and claimed it will play in the 20's and lower, delusion, and a fraud as well.

How sure are you of yourself?

I can tell you, I've had the LS-9 designed line arrays right next to my PR subwoofer that will play flat to 25Hz(in room), and run a recording I engineered that has frequencies into the low teens, and possibly lower, and I can tell you for sure that they will play lower than 20Hz.

Do you want to call me a liar?

As it stands now, your positions are meaningless. You haven't even heard the LS line arrays and what is possible. If you did, you wouldn't be talking.

Why didn't you go to hear the LS-6's and LS-9's when you were at RMAF 2007 and hear for yourself?

Why didn't you prove it to yourself first, whether they are capable or not?

I can post reviews of the LS series line arrays, would you like to explain to those experienced audiophiles how full of BS they are?

Cheers

I'm not talking about non-linear behavior but the inherent low frequency resonances that are present in a planar driver regardless of the amount of drivers. You can see them by looking at impedance curves as well as with distortion tests. When you cross too close to / or below them you can have audible distortion and adding more drivers won't make it go away. This is true with ribbons or planar drivers.

As I stated before and in another post in this thread the in-room specs are meaningless. Anechoic and nearfield tests for bass extension are widely used and accepted in the industry as being the most accurate way to determine the actual bass extension of a system. I'm not calling you a liar - just asking for some proof with accurate nearfield measurements to back up your position. Is that too much to ask?

Actually I had very little time to go listen to anything at the RMAF and would rather stay and talk to visitors in our demo room. If I did go listen and then offer my opinion would it really matter to you anyway? I don't think so.

[S Clark]

The same acoustic principles apply to the low frequency extension for 1 or 100 woofers. Making a claim that a 6-7" woofer in a 2-way array will have 20's extension comparable to say a 10" or 12" driver is misleading and utter BS.

Apparently not according to owners and reviewers of the GR LS-6, reporting in-room measurements down into the high teens.

Regardless what a biased competitor of the LS6/LS9 line array says, these will play well into the low 30's and (in the case of the LS9) into the 20's.  I have heard them.  He has not.

[Chops]

Regardless what a biased competitor of the LS6/LS9 line array says, these will play well into the low 30's and (in the case of the LS9) into the 20's.  I have heard them.  He has not.

Oh I know. I have no doubt that the LS6/9 can hit those frequecies.

Heck, I have a pair of old but freshly refoamed DCM Time Frame TF-350's sitting in front of my open baffles right now. They only have a single 6" paper cone woofer and a .75" dome tweeter. To make a long story short, I have been listening to them all day and they have no problems reaching down to a usable mid-30's, even at a good rate of volume. I have a pair of DIY 3-way towers that I built back in '96 (I was only 16 yrs old then) that I still use in my bedroom. They have a single Vifa 8" tuned to 40Hz and these things can rumble around below 30Hz all day long as well, and at much higher volumes than the DCM's.

So in short, I have no doubt in my mind that the LS6/9's with thier 8 and 12 6.5" drivers can pump out some major bass.

And just for fun, here's the speakers I was just talking about...






And just for the record, here's a SynRTA plot of my DIY towers as they are in my bedroom, with no EQ or tone controls. (8" Vifa, 5.5" JBL mid, 2" Bose tweeter, Dayton 3-way xover, 2.4cf ported enclosure tuned to 40Hz). BTW, the mid in the picture is a Bose 5.5". It's an old picture I had from years ago when I used them as surrounds. I switched the mids out about 3 months ago to the JBL units. Not to shabby of a plot though, huh?!

[S Clark]

Very impressive! Both the FR graph and the cabinets.   

[Chops]

Very impressive! Both the FR graph and the cabinets.   

Thanks! I appreciate that a lot!

[Russell Dawkins]

That is an excellent plot! Not only nearly flat, but very slightly down-tilted as well as conforming to that old Bell Labs dictum of the product of the upper and lower -3dB (or 6 or whatever dB) points being around 400,000. 20 - 20k, 30 -13.3k, 40 - 10k, etc.

[Danny Richie]

I finally have a minute or two and wanted to respond to some things said here, some of which is very misleading.

This is a common misconception and I've seen other commercial array designs that make the same mistake.

First of all, Rick, you need to knock it off. Those of us in the know already know that I am the only person that has designed commercially available line sources using planar magnetic drivers and low crossover points so this was obviously directed at me.

Those other recent little digs, jabs, and bashes have not gone unnoticed either. While you have been very covert in you efforts and have not mentioned me or my company by name, most still know clearly who you are referring to.

Putting everyone else down does not build you up and only makes you look bad. Please stop it.

It is very apparent that while Rick is trying to talk about the technical aspect of the OP question, the responses to his posts are fanboys who do not understand crossover design.

Jim, calling my customers a bunch of fanboys is demeaning and insulting.

Furthermore my customers know what they have, they know what they hear, and completely understand the aspects and performance of their speakers. In short, they get it.

Rick insists on insulting them but has not heard them, does not understand, and does not get it. His off topic use of this thread to insult my customers is not appreciated.

The driver C-T-C spacing of the 6" woofers is the problem and because of that the planar would have to be crossed lower. With the PT2 you really cannot go low enough to make a smooth transition over to the woofers.

This is misleading and not at all true. Center to center spacing of the woofers in a line source does not determine the crossover point and has little to no bearing on it at all.

The amount of drivers has no bearing on how low a planar should be crossed... The same acoustic principles apply to the low frequency extension for 1 or 100 woofers. Making a claim that a 6-7" woofer in a 2-way array will have 20's extension comparable to say a 10" or 12" driver is misleading and utter BS.

This is also not at all true and shows a clear lack of understanding as to what is going on with the tweeter and woofer lines.

Whether you have one driver or 100, the the low frequency or F3 point does NOT go lower.

This is also not true in application. A 5, 6, or 7 foot line of woofers used in a line source design and used in a typical listening room environment (even in a large room) will not have a response that is anything like a single woofer in the same room even if loaded and tuned the same.

Two things happen when you use a line of drivers. You get coupling and cancelling, and you get them both at the same time. It all depends on distance and wavelength. Both effect the response curve tremendously.

The Neo8 is essentially comparable to a 2" mid dome in frequency response and are best used as a mid range rather than a tweeter.

This is not really true in any since either especially the custom variant that we are using in the LS-6 and LS-9. The playing surface on the front side is only 5/8" wide and has better off axis response than even a 3/4" dome tweeter. The output also extends to 40KHz so there is no problem with it covering the range from a small woofer all the way up to 20kHz. 

The in-room measurements that have been quoted don't accurately reflect the true bass extension of the woofers.

The in room response measurement always confirms the low bass extension in that room. 

The only way to do a fair and accurate comparison is to do a nearfield test that correctly sums the output of the port and woofer.

This is not at all true for a line source. The near field measurement only tells you the output level of a single driver. Even summing in the output of the port tells you nothing about what kind of output level one can expect in the lower range once the speaker is placed into a room. This is especially true if the port is on the rear of the cabinet.

Most people know that one can push the speaker closer to the rear wall and gain more output from coupling from the port and pulling it further out into the room reduces the output levels of the port in relation to the rest of the output.

Also doubling the distance from the rear wall will cause a 6db drop in output from the reflected energy that the port will have from the rear wall. So there is no way to splice in a port response to any level that will accurately represent the port output in a room.

But those woofers won't give you the same bottom end extension that a larger driver will unless you add a massive amount of active equalization.

This is not true at all either.

It's easy to do with an active crossover but when a passive crossover is involved, physics rears it's ugly head. Since I'm not a crossover designer, here's my suggestion.

Well I am a crossover designer and the physics are the same whether the crossover is passive or active.

I'm not talking about non-linear behavior but the inherent low frequency resonances that are present in a planar driver regardless of the amount of drivers. You can see them by looking at impedance curves as well as with distortion tests. When you cross too close to / or below them you can have audible distortion and adding more drivers won't make it go away. This is true with ribbons or planar drivers.

Yes this is true, but FYI, the Fs on the custom built planar magnetics from BG average about 268Hz. Also the magnitude if the resonance is very minor and only creates a very small rise in impedance on the magnitude of a couple of tenths of an ohm. So crossing them at 850Hz or even lower and creating a third to fourth order acoustic slope is no problem at all.

nearfield tests for bass extension are widely used and accepted in the industry as being the most accurate way to determine the actual bass extension of a system.

Again, not correct at all. It will NOT determine the actual bass extension of a system. It will only determine the bass extension of a single driver in an anechoic environment.

[jholtz]

The "bible" of line array design by Dr. Jim Griffin PHD. http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

Jim

[Danny Richie]

Other than an attempt at lifting Mr. Griffin to God like status was there a point to this post?

[FredT300B]

Rick an Danny, please re-read the sticky at the top of the line array circle and pay special attention to the part that's in bold below:

"It's customary in the first post of a new circle's facilitator to remind everybody to observe the rules of the forum. OK, you are reminded, and there's one that's especially important. I expect everybody to get at least a B- on their report card each semester under "Works and plays well with others". Participants who are commercially involved in line array speaker design are held to an even higher standard, and they are expected to consistently get A's.

Thanks for your consideration,

Fred

[S Clark]

Well, not being a professional, I can state my opinion . This still looks like one manufacturer criticizing  another ones products- and in this case, having heard the LS9's I can categorically state that the one quoting the laws of physics regarding what a 6" driver will do is absolutely incorrect.  My suspicion is that it was an attempt to bash a competitor for personal gain and therefore constitutes unethical behavior. 

[Brucemck]

Having heard and purchased designs from both I know with certainty that both Rick and Danny build very, very, impressive speakers.

Reading the posts is sort of like what I suspect watching Iron Chef would be like without the deep appreciation the two teams have for each others' cuisine.  What I love about Iron Chef, and Rick and Danny's products, is that they take the same basic list of ingredients, same basic score sheets, and generate wildly differing offerings that are both far better than anything you'd ever find commercially available.

[gme109]

"I sat here in this room for a good long while - chatting most of the time, but I did get to hear the system over several songs.

Several bands of frequencies were much more compressed than others, and the highs lacked delicacy and finesse. We've heard a early version of the amps up here at Audio Federation, and the scuttlebutt is that they have only gotten better. We are not fans overly much of the Grand Prix Audio turntable, but it is unlikely to be the culprit. Their racks don't completely suck, and we even recommend them for people shopping in price ranges below that of HRS*, though that amp stand setup makes me nervous."


This quote is by someone else, not me. I'm just wondering what might be causing the compression that this person is hearing?

[pbrstreetgang]

The room, and the 50 watt amps. Here is what stereophile said of that room "Truth be told, these huge speakers need more than 50Wpc to shine. Nevertheless, what I could hear was so inviting that my appetite was whet to hear them in my own listening room once they become available in a month or so."

Here is what they said of the LS-6 room "The pair I heard was cobbled together at the last minute, and was far from broken-in. Yet, coupled with a neutral, sensational-sounding pair of custom built Dodd Audio KT-88-based 280W monoblocks (normally $50,000/pair, available at the Show for a mere $30,000), Dodd battery-powered tube preamp, Dodd 1500W balanced power supply, and Kool Cables pure gold Silkworm cables and custom built power cables, the system sounded phenomenal. While the room itself overloaded during the final moments of the Ivan Fischer Mahler Symphony 2—Mahler is not made to be played softly—and it could not handle the full measure of Mahler’s percussion, the sound was full, rich, and monumental in scope. I was especially impressed with the glistening highs. This system made my mouth water. Even before their December release date, 100 pairs had been pre-committed to eager music lovers."

http://blog.stereophile.com/rmaf2007//index1.html

It is what other listeners said also- small hotel rooms with huge Full Range  line arrays

[Danny Richie]

I am not sure what the relevance of those post have here in this thread, but can't really debate or disagree with any of their subjective comments.

It is true that the 50 amps used to power the LS-9's did not have the drive to really control them well in the lower ranges. They were often driven at their limits to fill the double sized room to solid levels and when you run a tube amp out of steam it does sound a little compressed. The top end was also a little on the soft side as well, and lacked a little compared to other types of amps. However, the mid-range was really lush and very musical. With the right type of music and volume level it was quite magical.

I was also there in the room when Jason (from Stereophile) gave the LS-6's a thorough work out. I wish I would have had an SPL meter handy. He was easily hitting 100db plus level's during the crescendos and he did overload the room a few times with it. The speakers breezed through it though and the amps had head room to spare.

RMAF is always a blast. I can't wait until next year.  aa

[Rick Craig]

Well, not being a professional, I can state my opinion . This still looks like one manufacturer criticizing  another ones products- and in this case, having heard the LS9's I can categorically state that the one quoting the laws of physics regarding what a 6" driver will do is absolutely incorrect.  My suspicion is that it was an attempt to bash a competitor for personal gain and therefore constitutes unethical behavior. 

Trying to give a DIY person good information is unethical?