[AlliumPorrum]

Since DEQX is not exactly the issue of this thread, and I could not find a correct circle for the discussion about it, I started new DEQX thread in here: http://www.audiokarma.org/forums/showthread.php?t=483967. Please feel free to comment any DEQX experiences on that thread.

[jtwrace]

Post it in the Acoustics Circle.

http://www.audiocircle.com/index.php?board=73.0

or

The Lab
http://www.audiocircle.com/index.php?board=20.0

[dBe]

When is the upgrade package (wire, caps & connectors) for the servo amps available?   

I'll be sending a prototype to Danny in a couple of weeks to compare to the stock amps.  Mostly power supply work, but some changes in the servo feedback circuit and the crossover board.

Really.  No kidding.   

Dave

[Early B.]

I'll be sending a prototype to Danny in a couple of weeks to compare to the stock amps.  Mostly power supply work, but some changes in the servo feedback circuit and the crossover board.

Really.  No kidding.   

Dave

Will mod services be available for those who already own the stock amps?

[Danny Richie]

I'll be sending a prototype to Danny in a couple of weeks to compare to the stock amps.  Mostly power supply work, but some changes in the servo feedback circuit and the crossover board.

Really.  No kidding.   

Dave

Awesome!

[jtwrace]

I'll be sending a prototype to Danny in a couple of weeks to compare to the stock amps.  Mostly power supply work, but some changes in the servo feedback circuit and the crossover board.

Really.  No kidding.   

Dave

This is interesting as Brian (Rythmik) has told me many times that doing anything to the plate amp is a waste.   

[dBe]

This is interesting as Brian (Rythmik) has told me many times that doing anything to the plate amp is a waste.   

That is why it is called a prototype.

Dave

[dBe]

Will mod services be available for those who already own the stock amps?

Perhaps.  It remains to be seen if the designer (Danny) thinks it is a worthwhile mod package.  It won't be inexpensive.

I know what I think, but I am the Daddy.

Dave

[HAL]

Cool! 

[rythmik]

This is interesting as Brian (Rythmik) has told me many times that doing anything to the plate amp is a waste.   

No, you get the wrong idea. I do discourage customers to do any mod.  Some customers do ask the benefit of changing out the power filter and I did say the benefit of upgrading them to say Panasonic power caps may not be that significant (I used panasonic power filter caps in H600 amps so I have the idea of how they sound).  However, there are other components I insist to use. For instance, the current sensing resistor is Mills. It is $3 a pop. I could have used a el cheapo 10 cents cement resistor. But the sound coming out from it is so dry.  I also sparsely use OPA2134 vs TL072 (I will never use RC4558 which is one of the worst sounding opamps).  But I don't want to open up a can of worms. If I can do these component selection for the customers, I wil do it first. 

[AJinFLA]

Panasonic power caps may not be that significant (I used panasonic power filter caps in H600 amps so I have the idea of how they sound).  However, there are other components I insist to use. For instance, the current sensing resistor is Mills. It is $3 a pop. I could have used a el cheapo 10 cents cement resistor. But the sound coming out from it is so dry.  I also sparsely use OPA2134 vs TL072 (I will never use RC4558 which is one of the worst sounding opamps). 

Hi Brian,

Still enjoying my Servo 12s (since 04).
Can you explain what aspect of the soundwaves <200hz (subwoofer frequencies your amps operate at?) account for the changes in what you are hearing between these caps, opamps and resistors, etc? Are these amplitude, or some form of distortion variations being detected in the soundwaves <200hz? Do the heard changes reach the cochlea via these soundwaves, or by alternate means of conduction?
I'm quite curious to figure out whats going on here and you seem quite adept at relying on science for explaining things. Thanks.

cheers,

AJ

[AJinFLA]

I'll be sending a prototype to Danny in a couple of weeks to compare to the stock amps.  Mostly power supply work, but some changes in the servo feedback circuit and the crossover board.

Really.  No kidding.   

Dave

This surely means you are recovered now  .
Take care

[JohnR]

I am going to get you the Le figure that you asked me for when I measure them next. As of right now I do not have that figure to give you or I would have given it to you.

OK thanks. If it's a hassle don't worry about it but I'd be interested to know.

And! You guys are still bench racing the numbers of the drivers only.

You mean Brian is. After taking a swing at someone else's driver for its high Mms, he discovers that other drivers are lower, so then tries a different way to try and disparage the competition. That's pretty lame. Then we find out that neither of you even publish the correct specs for your driver anyway. I think that's called "egg on face."

 

[rythmik]

You mean Brian is. After taking a swing at someone else's driver for its high Mms, he discovers that other drivers are lower, so then tries a different way to try and disparage the competition. That's pretty lame. Then we find out that neither of you even publish the correct specs for your driver anyway. I think that's called "egg on face."

 

What are you talking about?  You compare the Mms of a driver with only half the excursion of SW12-16 and say its Mms is lighter. You could have used a 10" driver to compare the SW12-16. You are really something. Just because you have no other better things to do other than writing up some half baked understanding of how eletronics work. I have formal training of EE. I have a Ph.d degree in EE. What do you have? 

[Rclark]

Fair points: 1) didn't know it was inductance, not mass, that deals with accelleration 2) didn't know mass of own driver. (but intimately familiar with competitors)

[Rclark]

And Brian, I'm sure if I was talking to YOU, I'd probably tell you your sub was the best too. I bet if he had Dr.HSU in private message, he'd have  told him the same thing, that his was the best. You, after all, aren't just a regular forum guy, and I'm sure he didn't want you to feel bad.

Their initial, unbiased findings were that the HSU sub was just as accurate as yours, without servo.

[JohnR]

What are you talking about?  You compare the Mms of a driver with only half the excursion of SW12-16 and say its Mms is lighter. You could have used a 10" driver to compare the SW12-16. You are really something. Just because you have no other better things to do other than writing up some half baked understanding of how eletronics work. I have formal training of EE. I have a Ph.d degree in EE. What do you have?   Get a life!!!

I see.

Well, you were the one who brought up Mms (again, after Danny already did earlier in the thread). Yes, the Dipole12 has lower excursion than the SW-12-16FR (not half, though), and the relation to Mms is...?? Nothing?

I mean, seriously, when simple requests for technical information are met with evasion, misinformation and insults, something's gone wrong somewhere...

[rythmik]

Their initial, unbiased findings were that the HSU sub was just as accurate as yours, without servo.

You meant like the ULS15 in northeastern GTG vs  E15. The host (Gorilla) said the Rythmik E15 sounded "by far" cleaner than ULS15.

[JohnR]

Hey John,

I gave it a shot. I measured the same woofer using a standard amp (black) and overlaid it on the servo amp impulse response (red). The standard amp sent a full range signal so there is a ton of shorter lines in there. Sorry about that. I'll need to figure out a better way to compare impulse responses. Scaling of the two may be way off as well.



Maybe Brian can post a servo and non servo impulse or step response using the same amp or at least send the same signal via same crossover control settings.

Thanks for taking the time, but I think for a meaningful comparison, the filters would need to be disabled or at least the same. I assumed that would be easy for you to do as earlier you had said

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.

However, it turns out that when you do that, what is really happening is that the amp is unstable:

I tried disconnecting the sensing coil and shooting a response. Guys that own these can forget trying that. The amp was still looking for the feedback. The response was erratic in some areas and the output shot up quite a bit.

Which makes sense, although it does make your suggestion on subjectively comparing servo vs not rather pointless. What happens if you short the servo input on the amp?

Ideally, it would be "nice" to come up with a way to demonstrate some of these things being talked about, in a way that would enable other people to also do measurements so we could compare. Only in the interests is gaining and sharing knowledge... I realize that isn't really your priority, but you are after all posting in a non-commercial circle.

[rythmik]

Ideally, it would be "nice" to come up with a way to demonstrate some of these things being talked about, in a way that would enable other people to also do measurements so we could compare. Only in the interests is gaining and sharing knowledge... I realize that isn't really your priority, but you are after all posting in a non-commercial circle.

John, what you are asking is to send Danny to a wild goose chase. You don't understand. Impulse reponse can be transformed from frequency response and vice versa when the system is "linear" and "distortion free".  The two are mathematically the same thing. You also mentioned step function response. That is just an integral of impulse response. So all 3 are the same thing.  I have a custom FFT system and it does just that. I can measure an FFT and then plot the impluse and FR at the same time. If I want, I can do an integral and it comes out with step function response. You can do that with CLIO if you have one.  But the impulse and frequency response begin to diverge when the system is in nonlinear region. Then how do you quantify the distortion induced in the measurement. You need to specify at what outputs level that you want the measurement.  Danny does not have time to do this. I don't have time to do this.  To do a fair comparison, we need to EQ the two systems to have almost identical FR and phase response  and then push them to same large signal level with induced distortion.  I probably can do that if this were 3 years ago. I already got rid of all my Linkwitz Transform modules.