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Re: Subwoofer Servo Technology
peterb #144951 08/08/06 03:40 PM
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Quote:

I'd like to see more technically advanced Axiom products come to market,



Umm, the DSP onboard the new Axiom subs were Axiom designed and then programmed with months if not years of efforts by Jim, an Axiom tech guru whose programming expertise is obviously very good. Call me crazy but designing and programming computer chips is considered cutting edge technology and not expensive, if you have the time to do it (DSPs on modern receivers are virtually a couple of bucks per unit these days).

I watched Jim during this building process for the prototype EP600. He had dozens of sheets of programming code to work through, tweaking each individual Hz until the DSP made the driver work in producing an equal peak (flat response) across the sub range. This would have been followed by testing in the anechoic chambers followed by more tweaking. Since this specific code would ONLY work for a single speaker design (change the cabinet, change the acoustics), the same had to be done all over again for the EP600. Jim has probably coded near half of the Windows XP OS in his DSP programming of the EP subs.
The result?
The EP500 has less than a TWO DECIBEL variation from the average across the 20-95Hz spectrum!! This is phenomenal and better than the reproduction i've seen with parametric EQs and DEFINES the most accurate sound reproduction possible (a straight line frequency response)!!



Creating a speaker with a flat response is NOT an easy feat (if it were then everyone would have made one by now), if not impossible without advanced DSPs to control the output; so to say that Axiom DSP technology is not advanced, is somewhat off the mark, no?
Many audio components are simple things like copper wire and analog signals. Many more "technically advanced" (e.g. digital speakers which you plug into a wall) are not exactly audio bliss. Sticking a new fangled miniature plasma screen on the side of a speaker with touch screen controls for a whopping 8 band EQ to say it is more technically advanced does not make a good speaker.
Have a look at the extensive and advanced research that Axiom does in the course of creating and tweaking their speakers over the decades. The appreciation of this work comes from reading about it and seeing it first hand, something that many audiophiles never take the time to do.

Last edited by chesseroo; 08/08/06 03:41 PM.

"Those who preach the myths of audio are ignorant of truth."
Re: Subwoofer Servo Technology
peterb #144952 08/08/06 04:23 PM
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Hello peterb,

There is nothing new about servo-feedback design in subwoofers and Axiom isn't interested in servo-feedback designs. These have been around for decades and used by such subwoofer brands as Velodyne, PSB and Paradigm in numerous models that deliver very good performance, better than would have been achieved without servo-feedback integration.

However, Axiom believes that our DSP design in the EP500 and EP600 subs is superior to the older servo designs in a number of important ways. Without going into a long dissertation, using a custom-written DSP algorithm that contains all of the traits of our particular dual-voice-coil driver, the enclosure, our amplifier and the expected performance goals results in an integrated system that delivers much more linear performance and optimal output well into the sub-sonic region.

Moreover, using a custom DSP algorithm means that the sub can never be overdriven or damaged. The algorithm was arrived at throught constant measurements and test of the driver, the amplifier and the enclosure, with any non-linearities (deviations from the desired frequency response) compensated with new instructions in the digital code.


Alan Lofft,
Axiom Resident Expert (Retired)
Re: Subwoofer Servo Technology
chesseroo #144953 08/08/06 04:42 PM
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Me thinks you take offense WAY too fast. What I meant was:
"I'd like to see more, technically advanced Axiom products like the 500/600 come to market..."

Also, I didn't say or even mean to imply that DSP was a simple or unsophisticated technology. However, servo feedback systems, because of their dynamic nature, offer capabilities that are beyond what's possible with a static DSP implementation. Not that this is always the best or most cost-effective design, but intrinsically it's more complex and adaptable.

And please don't take offense (I own several Axiom speakers)but... a flat FR to 20 Hz at only 90dB is very good, but given the current competition, far from earth shattering performance.

Re: Subwoofer Servo Technology
chesseroo #144954 08/08/06 04:44 PM
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Quote:

Creating a speaker with a flat response is NOT an easy feat


Especially a subwoofer - less than 1/8 the audible frequency band, and 80x the trouble as the rest of audible sound.

Peter - you can imagine how your message would be taken... the unknown guy comes in and starts touting some new procedure or product... which is okay, sometimes there's something neat out there. It sounds a bit like an ad, that gets everyone's hackles up. Then, BAM! You rag on the Axiom sub line (especially the EP500 and 600 which represent a whole lotta R&D and the results speak for themselves - they opened a whole new class of subwoofer) and suddenly it sounds like an infomercial - like...

"Mopar owners - did you just buy a Charger with the new 5.7 Hemi? Well, it's okaaaay, I guess... but running it on new Malvoline 0W10 oil will really crank every last horsepower out of it... look at this animation hacked together by some kid learning After Effects at an unaccredited community college - 5w30 oil is thick, and thick creates friction - our oil HAS no viscosity, giving you up to 946 more horsepower *"

* 946 more horsepower statistic is a completely false, made-up number, don't sue us.

Bren R.

Re: Subwoofer Servo Technology
BrenR #144955 08/08/06 06:13 PM
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I agree that the 500 and 600 subwoofers put out by Axiom are really outstanding, and I have never heard one! These subwoofers have really gotten people to notice Axiom, even some people that don't care for Axiom speakers (with or without valid reason). Audio gurus from all sorts of magazines, design groups, and installers are praising the outstanding audio of the EP500 and EP600.

Peter, I think that you are reading too much into Chesseroo's post. He isn't coming down on you, just stating some facts, and asking you to consider them compared to your statements (like when he typed "No?"). It is just to spark conversation. Don't get discouraged or frustrated. Go ahead and keep posting your thoughts and even better some facts about the technology, then we can all speak to it with some technical insight.


Farewell - June 4, 2020
Re: Subwoofer Servo Technology
nickbuol #144956 08/08/06 07:29 PM
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I'm always interested in learning. I aspire to inclusiveness.

Quote:

I was hoping to find someone who actually knows something about physics and electrical engineering who could discuss why Axiom went DSP when low cost servo technology is available




I think Alan answered this question above. Axiom - at its heart an R&D company - believes the DSP path offers superior performance.

Quote:

However, servo feedback systems, because of their dynamic nature, offer capabilities that are beyond what's possible with a static DSP implementation. Not that this is always the best or most cost-effective design, but intrinsically it's more complex and adaptable




I'm going to suggest "debatable" here rather than "intrinsic". Your earlier comment about finding "somebody who actually knows something" leads me to think that your assertions about the "intrinsic" benefits of certain technologies may come from other sources. Care to cite them? "Technical" Forum and all that.

Quote:

a flat FR to 20 Hz at only 90dB is very good, but given the current competition, far from earth shattering performance




Are you going to suggest the alternatives by name and cite the quantifiable data, or just leave this hanging out there? What's "better"? How do YOU KNOW it's "Better"? How much does "better" cost? How are we measuring "better" this week?

Look, I'm not trying to be a hard case here. I like fun new blinky stuff that plugs in as much as the next guy. You are advocating and defending technology that is "different" - not "new" - while dancing perilously close to "Axiom doesn't know what they're doing if they're not pursuing THIS".

I liked Alan's reply. And yes, I do get grumpy before lunch.


bibere usque ad hilaritatem
Re: Subwoofer Servo Technology
peterb #144957 08/08/06 08:55 PM
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Quote:

P.S. I've never seen the AVS forum - what's the deal with them?



The AVS (Audio Video Science) forum is a large public forum, that has a huge amount of information (and an equally large, if not greater, collection of misinformation). It can be interesting and entertaining, and contentious. It is rarely dull. The "Continue to Main Forum Index" link will take you to the heart of the matter.

Here is the specific thread, to which I alluded, in which Rythmik has particpated..............all 19 pages of it.

The Ultimate shootout begins ...


Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton
Re: Subwoofer Servo Technology
tomtuttle #144958 08/09/06 02:42 PM
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So cute the way y'all spring to defend Axiom's honor against any perceived slight. Touching really.

I love Axiom, I buy their products, I know the whole story about Floyd Toole, the NRC etc. But do they represent the last word in audio? Are all technical approaches other than theirs wrong, a priori? Give me a break.

Re: Subwoofer Servo Technology
peterb #144959 08/09/06 02:53 PM
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A priori?
Interesting choice of words considering it was used in an incorrect context. A priori to what?
The sentence doesn't make any sense without a reference.
Neither does your argument about how Axiom should be pleading at the doorway of Rythmik Audio for their amazing, "new" technology.
I guess i'll just go back to defending my Tannoys...oh i mean my Monitor Audi...no no, my Axioms because that's where my heart and soul of speakers is at and i have nothing better to do.


"Those who preach the myths of audio are ignorant of truth."
Re: Subwoofer Servo Technology
chesseroo #144960 08/09/06 03:03 PM
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Main Entry: a pri·o·ri
Pronunciation: "ä-prE-'or-E, "a-; "A-(")prI-'or-"I, -"prE-'or-E
Function: adjective
Etymology: Latin, literally, from the former
1 a : DEDUCTIVE b : relating to or derived by reasoning from self-evident propositions -- compare A POSTERIORI c : presupposed by experience
2 a : being without examination or analysis : PRESUMPTIVE b : formed or conceived beforehand

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