[Freo-1]

This shootout is useless for us. Those guys are home theater buffs. Two channel audiophiles are a different breed, and our desire for quality bass is quite different. I have two subs -- one for HT and one for audio, and they are very different for obvious reasons.
 

Agree 100%
 
For HT, a large servo sub is excellent.
 
However, audio only subs are a different breed of cat. For my two channel audio setup, I'm currently using a TBI Magellen VIII su with excellent results. This goes deeper than Hoffman's Iron Law says it should, and it does so with very low distortion. And yes, it's fast enough to work with Maggies.
 
http://www.dagogo.com/View-Article.asp?hArticle=876
 
Danny's subs are also excellent performers. The Genesis G 928 also performs well.  There are a number of subwoofer designs and methods out there to achieve good quality bass. The problem is getting them to work with one's specific setup.  To a large extent, it depends on what one values for bass reproduction.
 
 
 

[Danny Richie]

Danny, an off-topic proposition for you.  Since you're so big on vehicle acceleration analogies, how about we have a little competition on a real drag strip?  I win you give me a pair of your dipole servo subs.  You win and I'll buy a set at full retail?  The only criteria is you race your daily driver and I race mine.  Deal?   We'd have to meet up somewhere between Texas and Seattle. 

I do like a challenge, but that is too far for me to drive for a servo sub sale. And I am not really that interested in making my daily driver a drag car. I have already been there and done that.

[Danny Richie]

Frankly, his (and his acolytes) constant hyping of everything he makes and consequent slagging off of every other manufacturer is rather tiresome and why on some respected forums mention of his products is specifically (and uniquely) banned.

Nope, that wasn't it at all.

It was one forum and the reason they banned all discussion of any GR Research products is because they are a bunch of flat earthers. They believed that things like wire, fancy inductors, and boutique capacitors are a bunch of snake oil. I think they felt the same way about burn in effects. My debates with them on those topics never ended well for them. Then when I backed off my customers kept on by giving personal listening impressions on the differences in capacitors etc. And then it got to where if any of my customers posted anything about their speakers someone would have to just in and tell them how they wasted all their money on those fancy caps that will never make any difference. Then off they would go again.

So they finally just banned discussion of our products to end the debating.

[Danny Richie]

Danny is being disingenuous here.

A decent dipole sub can easily hit 105db somewhere in the bass. At high enough frequencies they will output more than a monopole. Mine (2 x AE IB12s) will theoretically do 113 db at 71Hz and 104 at 50Hz. However they will only do around 80db at 20Hz.

So while his GR subs can probably hit 105db, and can also probably play flat to 20Hz, they can't do both at the same time.

My first year at RMAF with Super-V's we were hitting 100 plus db peaks in that room down to 20Hz. No joke or exaggeration. We measured them, and I have witnesses.

[Danny Richie]

Well... right. Box subs and OB subs sound different. I can see the reasons why a boxed sub would benefit from servo as there's nothing you can do in designing the driver to remove the compression of the air in the box. With a driver in free air, though, it's different... This thread has pretty much convinced me that servos for OB are basically a gimmick. (Not that I was about to buy any any time soon anyway, I have enough OB drivers to last me a while...)

So I am selling a gimmick? Really?

Please let me point out the obvious. I have servo controlled woofers for sealed box and open baffle applications. I am very familiar with how well they work. I have heard them. And between the two I'd have to say that the servo control makes more difference in the OB configuration.

Want to see just how effective the servo system is on our OB drivers? Easy. While listening to them, unplug the sensing coil and listen to the difference. With the sensing coil unplugged it will be just like any other high Q uncontrolled (non-servo) woofer. Then reconnect it and listen again. The difference is not subtle. It is a BIG difference.

And I would also point out that you have not heard either. Man, we are going to have to figure out a way for you to hear these.

[Danny Richie]

Another thing that has me "baffled" as I just thought of it.. Does the bass in music have a "braking" and "accelerating" phase? I think, logically, I'd prefer a driver that could just follow the signal as closely as possible.

Exactly! That is exactly what the servo control system does. It more closely matches the movement of the driver to the input signal by reducing continued woofer movement that exceeds the signal length.

[Danny Richie]

Weee... ellll... you know, this is where the claims begin. Earlier in this thread there was the claim that lower moving mass was better. When it was shown that a different driver that is otherwise pretty much the same thing has almost half the moving mass, the claim was altered to the mass doesn't matter, what really counts is the whole system. The question about Le was avoided, twice, with the answer now being that none of the T/S parameters matter anyway.

I dunno man. As they say, YMMV...

You missed the point.

Yes low moving mass is good and the AE looks great in that regard. However, your comparisons are not apples to apples. You can't just look at the measured T/S parameters and draw a conclusion because the you have to look at the parameters as a whole in an application. And in the servo controlled system the total system parameters are not the same as the driver parameters.

It's just like when you take a woofer and put it in a sealed box. The total Q of the system (woofer and box) is not the same anymore compared to just the Q of the woofer alone.

The servo system is the same way. You can give the system a total Q that is much different than the driver alone and you can change it on the fly.

It's like using a field coil driver and having control over the voltage that creates the field strength. You can completely change it at will.

That is why I am telling you that it doesn't matter. You can't just go by the T/S numbers of the driver.

[Danny Richie]

For what I know, DEQX isn't adding anything to the signal path. Just the opposite; the main reason I'm interested on it, is the possibility to get rid off of one of the biggest problems in the signal path; crossover's analog components. During my 20 years of hifi hobby & DIY, I have noticed that the one place to get great improvements is tweaking the crossover with better quality components. Speakers even with 5k price tag seem to have a bottle neck in their XO's. Yes, amplifiers and DAC's do always add more or less coloration to the sound, but the coloration that crossover adds seems to be much bigger, and component changes can have a huge effect to the sound.

Of course, I don't have any own experiences on DEQX yet. But, during last 6 months I have read pretty much everything that there is written about the DEQX in the internet, and I haven't found a *one* article where DEQX would have not been better than original analog crossover. I found few articles where the result was not so great at first, but after more studying, it was found that it was not used correctly. It surely isn't simple "plug and play" solution, that's for sure.

And concerning the DAC's. First of all; Burr Browns on HDP-4 have been getting really good reviews everywhere. HDP-3 was way behind in this area, and older 2.6 seems to be total crap. Secondly; HDP-4 has digital outputs, so if really wanted, you can use any DACs you preferr.

Man I hear what you are saying and in principle you are completely right. It should sound better if the crossover were all digital and there were no passive parts in the signal path.

Unfortunately in practice that is not the case.

In my personal opinion, when it comes to sound quality, my current front end that I am using and a passive crossover on the speaker using good quality parts (actually more like best quality parts) still crushes any currently available digital system.

And it is not just about what DAC chip the converter is using. I have really learned this year that the sound quality of a DAC is about FAR more than just the chips used. There are a ton of other things that can add noise to the signal.

[Danny Richie]

I've followed this thread with a combination of amusement and amazement and finally have to interject.

If anyone is familiar with the old analog synth Roland 808 drop, the fundamental is 18Hz.  At RMAF we had people's pant legs flapping and glasses in the bathroom rattling around on the granite countertop.  The music piece in question is Pete Belasco's "DEEPER".  A low frequency tour de force.  Anyone that was there can attest to the feeling of air shuddering in the room at 18 hertz as well as the limit of audibility sound associated with it.

A high Qt, high excursion, properly implemented (NO accelerometers), servo controlled subwoofer is anything but a "gimmick".  It is an experience that is life changing.  At least it was for me.  NEVER again will I go back to big box colored bass.  This is the real deal

YMMV until you hear 'em.

Dave

I remember that. That was the first year with the Super-V and the first year we had that track. One of you guys came into the room while we were playing that song and took me out into the hallway where I was showed the wall. The wall in the hallway was moving a good 1/8 or more. It looked like it was going to come apart. And that wall had a closet or bathroom between the area that the system was set up in. We were rocking the building with that low note in that song.

[sfdoddsy]

Disingenuous?  Not at all.  I know because I was there.  SPL's in the 105-106dB range for the loudspeaker - NOT the sub by itself.  Powerful reproduction @ 18Hz as mentioned later on in this thread.  Tight, tuneful, power bass at ANY volume level.  Beyond that all of this is apples and oranges.

Dave

Actually, he makes that very claim in post 143 of this thread. 100db at 20Hz.

According to the SPL calculator on the Linkwitz site, it would take around 8 dipole drivers with the parameters of the GR Research one to create those kind of numbers, even generously adding 6dB for floor boundary effects.

Servo power does not negate the laws of physics.

And Danny, if by 'Flat-Earthers' you mean generous folk who freely donate their time and considerable technical knowledge to a bunch of strangers in a friendly unbiased fashion, helping them create really good sounding speakers without trying to flog products and mumbo-jumbo to the credulous, then I suspect they'd happily plead guilty.

Thanks for demonstrating my point.

[lowtech]

I do like a challenge, but that is too far for me to drive for a servo sub sale. And I am not really that interested in making my daily driver a drag car. I have already been there and done that.

Sale?  That's mighty presumptuous of you.  It would likely be much more along the line of give-away.  And, my daily driver is hardly a "drag car".  Let me know if you reconsider and decide to drive to winter CES.  They have a nice drag strip not far off the strip. 

[JohnR]

Want to see just how effective the servo system is on our OB drivers? Easy. While listening to them, unplug the sensing coil and listen to the difference. With the sensing coil unplugged it will be just like any other high Q uncontrolled (non-servo) woofer. Then reconnect it and listen again. The difference is not subtle. It is a BIG difference.

Should be easy for you to demonstrate with measurements then, right? Let's see them.

[jtwrace]

I have really learned this year that the sound quality of a DAC is about FAR more than just the chips used. There are a ton of other things that can add noise to the signal.

and wire, caps, connectors....

It's all about design and implementation.  ODAC proves this wtih real objective data hence the name. 

[jtwrace]

Should be easy for you to demonstrate with measurements then, right? Let's see them.

+1

[sfdoddsy]

Speaking of measurements, it should be easy enough to prove the output claim too.

Here's a site with test tones:

http://www.testsounds.com/

SteveKelbey has a set of Super Vs. Just get him download the 20Hz test tone, fire up an SPL meter, play it at 100dB and report back what happens.

[jtwrace]

Hopefully we'll see some 8" servo data too as they are supposedly capable of 20Hz.   

[stevenkelby]

Speaking of measurements, it should be easy enough to prove the output claim too.

Here's a site with test tones:

http://www.testsounds.com/

SteveKelbey has a set of Super Vs. Just get him download the 20Hz test tone, fire up an SPL meter, play it at 100dB and report back what happens.

Thanks for that link, very useful!

I don't have an SPL meter yet but promise to get one and report back here with the results!

[Rclark]

Hopefully we'll see some 8" servo data too as they are supposedly capable of 20Hz.   

 They are?

[jtwrace]

Danny is being disingenuous here.

A decent dipole sub can easily hit 105db somewhere in the bass. At high enough frequencies they will output more than a monopole. Mine (2 x AE IB12s) will theoretically do 113 db at 71Hz and 104 at 50Hz. However they will only do around 80db at 20Hz.

So while his GR subs can probably hit 105db, and can also probably play flat to 20Hz, they can't do both at the same time.

In spite of this being pointed out numerous times, he persists in fudging in the manner above.

Frankly, his (and his acolytes) constant hyping of everything he makes and consequent slagging off of every other manufacturer is rather tiresome and why on some respected forums mention of his products is specifically (and uniquely) banned.

It makes many people dismiss all of his products as nothing but hot air.

I recommended his servo subs in the OP's other thread, but I did so grudgingly for the reasons above.

Well said.

[dBe]

Or, for more functionality:

http://test-tone-generator.fyxm.net/

Dave