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#162474 - 04/02/07 08:39 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
bugbitten Offline
connoisseur

Registered: 04/06/05
Posts: 2339
Loc: Madisonville, KY
Quote:

Update: Well I worked with Emotiva today over the phone. For starters, they went out and purchased a Radio Shack Analog meter like mine. In their labs they use much higher quality test equipment, for example, "Audio Toolbox" meters. This way they could try to recreate what I was seeing on my meter.

Anyway, their initial findings was that the amp was truely meeting the specs of 300 watts into 4 ohms, in fact, it was actually reading 380 watts when the amp protection kicked in.

Another finding, was that the Radio Shack meter is great for calibration of speakers, but not really the best for lab test readings. During the dynamic parts of songs where the RS meter would jump from 110dB to 115 or 116dB, their more accurate Audio Toolbox meters were showing 20+dB jumps.

Now, the conversation moved onto the amps Wave Form Limiter? I really didn't understand what this does, but it sounds like this was the main reason the amps are shutting down. Emotiva mentioned the amps will do 780 watts RMS no problem, from past tests in the lab, however, I believe this Wave Form Limiter protection restricts what gets passed onto the speakers?

I talked to Axiom, and was told the 80's have been run for 2weeks straight at 24hrs a day at 700 watts continuous with peaks reaching 1100 watts, while testing the new amp line. So I know the Axioms can handle the wattage.

Resolution:

Emotiva showed me with very detailed instructions/pictures how to remove one of the resisters which gives the Wave Form Limiter its input signal. I"m not worried about making this modification, as I've worked a little on circuit boards/soldering, etc.. Basically it just involves removing this resister with some small snips, no problem.

The tests Emotiva did today, showed that with the amps being pushed very hard, they will produce just over 1KW. The Resistor being removed is where the Wave Form limiter gets it’s input signal from. Now by removing it, this will disable the limiter whereby making the amplifier like most amps on the market today. The amp is still a dual tracking class H design and the protection circuit is still in place, only the limiter has been disabled.

Without the limiter it is possible to get out peaks in excess of 1KW if pushed hard enough which would easily toast most speakers. I would not recommend this modification if your not having a problem, and would contact Emotiva if you are...

Randy




I just happened to be in the Emotiva lab Friday while Robert and Dan were doing the second of these procedures for another unamed client. I watched as they tested an amp module using a subwoofer. I can attest that the amp was pushing beyond 300 watts.

I will have more to say later about my visit with Emotiva.

I also went back today and bought an MMC-1.

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#162475 - 04/02/07 10:33 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
pmbuko Offline
shareholder in the making

Registered: 04/02/03
Posts: 16280
Loc: Leesburg, Virginia
Here's an analogy:

Randy: Doctor, when I try to maintain my 100-yard dash pace throughout the marathon, I end up puking after the first 1.5 miles. What's wrong?

Doctor: Nothing's wrong. Stop doing that.



I do see how wanting an amp to perform to its specs is desirable, even if you'll never have to use the rated capacity without earplugs, isn't really all that strange. I'm sure Emotiva is grateful for your out-of-the-lab, real world tests and feedback.
_________________________
"I wish I had documented more…" said nobody on their death bed, ever.

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#162476 - 04/03/07 10:27 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: pmbuko]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13337
Loc: Iowa
Ok, here is my latest information from Emotiva, without going into great detail on their amp design.

"I really can’t go to deep into the design or operation of the wave form limiter as this is technology that is proprietary. What I can do is give you a basic overview of what it does. This type of limiter is what would normally be found in broadcast equipment like what is used at radio stations, television stations etc. It is used and employed to prevent the outgoing signal from clipping and the same principle of operation applies here. The limiter looks at the incoming signal in relation to the output as well as a number of other variables like current draw, rail voltage, etc. To understand what it does, you need to understand what the design criteria of the amp is. The EPM-300 amplifiers are designed to produce 300 watts RMS into a 4 ohm load unclipped. If the amplifier is pushed beyond this point a normal amplifier will go into clipping which could easily cause damage to the speakers. You see when an amplifier clips the distorted wave form starts to square off which generates harmonics across the bandwidth relative to the fundamental frequency. It is these harmonics that contribute to an increase in power output from the amp that will super heat the voice coils and cause them to expand and deform where by they will either rub against the motor structure and fail or will simply burn through the wire in the voice coil again casing the speakers to fail and to make it all worse this is not always apparent as the distortion is often masked by the level of the fundamental frequencies. Now with the limiter, if the amp is pushed beyond the designed levels, the limiter will engage where by reshaping the wave form and bringing it within a safe operating range and thereby protecting the speakers. So by removing R12, you will deactivate the limiter and the amp will now go into clipping which could cause possible damage to your speakers. So are you getting more power without the limiter? Not really, you see the amp will still only produce 300 watts RMS clean into a 4 ohm load, but now it can be pushed well beyond that but the signal will now be clipped."

So I really have a decision to make here guys and I need your help. I know the 80's can handle gobs of power according to my above statements, but what good is that if the amp driving them is clipping?

I really love this amp as the sound/power is great, however, once in a while when I audition, people like to hear something cranked up a bit. If I can't go past +3 on my Denon knob once in awhile without the dang thing shutting down, what good is it...

I could with the Denon, however, I could easily notice the Denon was straining and clipping, it must not have the same limiter inside.

This drives me nutzzzzzz.
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162477 - 04/03/07 10:47 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
pmbuko Offline
shareholder in the making

Registered: 04/02/03
Posts: 16280
Loc: Leesburg, Virginia
Quote:

however, once in a while when I audition, people like to hear something cranked up a bit.




Did you buy the Emotiva for you or for people??

If it only shuts down when you play it louder than you'd ever listen to, I fail to see any real problem. The M80s can handle gobs of clean power, but clipped power can damage any speaker.

The choice is simple: If you can get over the fact that you can't successfully demo TEH AWESUM P0WER that the Emotiva is capable of (in the lab, at least), then keep it. If it'll eat at you constantly, return it.
_________________________
"I wish I had documented more…" said nobody on their death bed, ever.

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#162478 - 04/03/07 10:59 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: pmbuko]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13337
Loc: Iowa
I don't think you guys are following everything. You have to keep in mind my room is 8,000+ cubic feet, a lot of volume to fill.

100-106dB's from 12ft away is loud, but I don't think it is apples to apples say for someone in a 12 x 15 room or so.

Randy
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162479 - 04/03/07 11:02 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: pmbuko]
Hutzal Offline
connoisseur

Registered: 07/26/06
Posts: 2102
Loc: Hollywood. (Canadian @ <3)
Randy,

Like pmbuko says, how often are you really going to be listening to those levels?

On the other hand, if you are the type of person that it will just bug you when you're watching movies at reference level (75db) and knowing that you can't go over 100db...and it is constantly on your mind, then I would return the Emotiva, get a different amp that can give you the levels you are wanting.

Perhaps call Axiom about their 8 channel amp and see when it will be released

I am one of those types of people that wants everything to be perfect, something like this would indeed bother me greatly and I would probably return the amp.

Just my 2 cents!

-Hutz
_________________________
Producer | Composer
www.robbhutzal.com

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#162480 - 04/03/07 11:13 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Lorenzo1000 Offline
aficionado

Registered: 02/07/04
Posts: 537
Loc: Winterpeg
I say return it and look for a good used amp on Audiogon. If you are only using it for the 80s it shouldn't be too hard to find a reasonably priced 2 channel amp that will do the job.
_________________________
2xM80 VP180 2xQS8 2xM3 HSU STF3 LG 60PS11 Denon 3808 ATI 1506 LCR 2xATI 1502 Oppo BDP-83

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#162481 - 04/03/07 11:28 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: Lorenzo1000]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13337
Loc: Iowa
thanks Lorenzo,

My goal in all of this was to eventually to drive my entire system with this modular/chassis amp design. Being a monoblock design, you can add modules as budget allows. I already have 3 amps driving my l/c/r with plans to purchase their 2-channel modules for the surrounds. Having everything in one chassis and saving space was plus also.
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162482 - 04/03/07 11:36 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Lorenzo1000 Offline
aficionado

Registered: 02/07/04
Posts: 537
Loc: Winterpeg
There are 3 channel Acurus amps at 200 WPC that run around $500 - $600 on Audiogon all the time. Other good amps for the $$$, ATI, Sherbourn, Sunfire Cinema Grand, Marantz Ma 700 monoblocks, Marantz mm9000.
_________________________
2xM80 VP180 2xQS8 2xM3 HSU STF3 LG 60PS11 Denon 3808 ATI 1506 LCR 2xATI 1502 Oppo BDP-83

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#162483 - 04/03/07 11:57 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: Lorenzo1000]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17782
Loc: NoVA
Isn't 100dB at the listening position 100dB, no matter how big the room is? I'm confused.
_________________________
I am the Doctor, and THIS... is my SPOON!

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