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#162534 - 04/04/07 04:04 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: MadScientist]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
I agree with mdrew although I won't go as far as to say this is a design issue. It could be a manufacturing issue. We just don't know.

MadScientist's graph suggestion is a good idea but it's impossible to understand the graphs without understanding the test procedure and equipment used. And this is where things get very complicated and require careful study.

For what it's worth, here is the performance that I am experiencing with my M80s in my very bright, 4000 cubic foot space. The voltage is measured with a $30, analog meter from radio shack that has no specs whatsoever. I am confident SPL is accurate to within +/- 1 dB for this frequency. I only went up to -10 on my amp's gain because I was worried about damaging a driver.

Both channel levels are set to 0, left channel RMS voltage measured with a 1 KHz tone (the test CD says that this is a 0dB tone; all other tones on the CD are -10dB). SPL is C-weighted, slow with two channels from 12 feet away. The impedance (Ohms) was taken from the Axiom graph that Randy posted. Power is in watts for my left channel. The power for both channels is of course double the power for a single channel. My Denon amp is rated 90WRMS + 90WRMS for 8 Ohms with 0.08% THD (over audible frequency range) and 125WRMS + 125WRMS for 6 Ohms with 0.7% THD at 1 KHz. No rating is given for 4 Ohms. Based on the 1 KHz input frequency, the M80s are operating at 8 Ohms.

amp.....Vac.....Z......Power.....SPL
-30......0.9....8.5......0.1.........75
-20..... 2.5....8.5......0.7.........84
-10..... 9.5....8.5......11..........92

I haven't spent any time interpreting these results to understand if they "make sense" or how the apply to Randy's situation. Comments from anyone?

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#162535 - 04/04/07 04:38 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: real80sman]
MadScientist Offline
regular

Registered: 04/03/07
Posts: 8
Quote:

Randy, I read through the whole thread and by the time I got to the end, I forgot half of what I read......

So, is or is not the EMO delivering it's claimed output without shutting down? That's the only question that really matters. If it only shuts down once you push past this point, than nothing is wrong. The protection circuit is doing what it's supposed to, and the guys at Emotiva have done their job. If it's not delivering the rated power, then they have more work to do.

If it is delivering the goods, and if you'll be pushing past this point on a regular basis, send it back - you need a bigger amp, man.

It would be nice if Ian or Alan would chime in on how the Sherwood amp performed during their torture tests with the 80's.




I supose it is a matter of personal preferrence, but I agree with 80sman here. If the amps do what they state before shutting down, then the only problem is you need an amp with more power rather than the amps being flawed.

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#162536 - 04/04/07 04:41 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: michael_d]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13333
Loc: Iowa
Here is Dan's response to me on AV123....

Dear Randy,
I know that Lonnie has explained the situation to you with respect to amplifier protection thresholds into 4 ohm loads. I would like to reiterate for all MPS-1 owners, if I may.

Let me be perfectly clear; the amplifier will not inhibit into 3-4 ohm loads unless the soft limiter is sensing significant levels of distortion. It doesn't shut the amplifier down "for no good reason". If you are driving your amplifier into a four ohm load and it inhibits, it is because the soft limiter has been driven to the point it sees you have exceed a preset output volt/amp threshold that we have set. Under these circumstances, the amplifier is being driven into pretty hard clip. You don't hear it as such because the soft limiter is doing its job. It is reducing the hard edge clipped waveform into something more benign. But, when you listen to the amplifier under this condition, you can clearly hear the change as the amplifier sound appears to soften and dynamics are affected. This is intentional and was designed to keep you and your speakers safe and sound. Our goal was to make a better product; for some people, this is seen as a negative attribute. One reviewer thought the amplifier didn't make enough power; we explained to him our thinking behind the limiter and he didn't get it. He felt is made the amplifier seem less potent than it really is. Our desire to build a cool feature into the amp may have backfired on us with some people. I guess you can't please everyone!

To address your comments about SPL's measurements and your displeasure over only being able to reach SPL's in the low 100+dB range at 12 feet in your room, as measured by your RS meter; this is not a scientific method of determining real power output. The RS meter is not a peak reading meter and its VU metering ballistics are suspect. Your measurements are low by at least 6-10dB. Also, at 100+ dB the microphone in the in the meter is compressing which adds to measurement errors. The problems with this test methodology go on and on.

Also, hanging a DVM across the speakers while playing music is not going to provide meaningful data either. I don't want to go into a long technical dissertation as to the problems with this measurement technique, but please trust me, your approach is not correct.

We have given you a solution for the address your unhappiness with the protect threshold which involves removing the soft limiter. This will make the MPS-1 behave exactly like the IPS-1 and and LPA-1 amplifiers.
It will not make the amplifier bad or dangerous to your speakers. It will will make the amplifier behave like 99%of all other all other amps on the market. You will only have hard clipping present on the amplifier output when you push it beyond its power ratings. You may find that you hear the sounds of distress more readily this way as the soft limiter will not cover up this over load condition. At then end of the day, it is up to the judgment of the listener to exercise common sense when we hears obvious signs of distress in his system.

In any event, it will eliminate you major complaint. The unit will still be under warranty, all normal protect functions are still in place, and if you are not happy, we will return your module to its original state for you free of charge.

I suggest you try it on your main left and right modules and see what you think! You may be very pleased with the outcome; and you have nothing to lose!

I hope this helps clarify our recommendations and the thinking behind our decisions. Please let us know if this addresses your problem. I'm sure many other people would like to hear your feedback on this issue. As always, feel free to contact us with any other questions or issues you may have.

Thanks for your support.
Best regards,
Dan
__________________
Dan Laufman
President
Emotiva Audio Coporation

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

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#162537 - 04/04/07 06:29 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
Quote:

Let me be perfectly clear; the amplifier will not inhibit into 3-4 ohm loads unless the soft limiter is sensing significant levels of distortion. It doesn't shut the amplifier down "for no good reason". If you are driving your amplifier into a four ohm load and it inhibits, it is because the soft limiter has been driven to the point it sees you have exceed a preset output volt/amp threshold that we have set. Under these circumstances, the amplifier is being driven into pretty hard clip. You don't hear it as such because the soft limiter is doing its job. It is reducing the hard edge clipped waveform into something more benign. But, when you listen to the amplifier under this condition, you can clearly hear the change as the amplifier sound appears to soften and dynamics are affected. This is intentional and was designed to keep you and your speakers safe and sound. Our goal was to make a better product; for some people, this is seen as a negative attribute. One reviewer thought the amplifier didn't make enough power; we explained to him our thinking behind the limiter and he didn't get it. He felt is made the amplifier seem less potent than it really is. Our desire to build a cool feature into the amp may have backfired on us with some people. I guess you can't please everyone!




This is not how a waveform limiter works. A waveform limiter reduces the gain in order to maintain stability. It does not at all affect dynamics. From the description above, Emo does not employ a waveform limiter but rather a soft clipper...hence the effect on reduced dynamics as the peaks get soft-clipped. And I understand the struggle they have with such a feature. They should have made this feature configurable and provided a very well-written description in their manual. I guess this is an opportunity for improvement. Frankly, I don't think the designers implemented what the product champion(s) originally envisioned and the champions are finding out now at a late stage.

Quote:

To address your comments about SPL's measurements and your displeasure over only being able to reach SPL's in the low 100+dB range at 12 feet in your room, as measured by your RS meter; this is not a scientific method of determining real power output. The RS meter is not a peak reading meter and its VU metering ballistics are suspect. Your measurements are low by at least 6-10dB. Also, at 100+ dB the microphone in the in the meter is compressing which adds to measurement errors. The problems with this test methodology go on and on.

Also, hanging a DVM across the speakers while playing music is not going to provide meaningful data either. I don't want to go into a long technical dissertation as to the problems with this measurement technique, but please trust me, your approach is not correct.




I don't disagree with the underlying message which is "Be aware of the inherent limitations of your measuring set-up and apparatus". I don't have a RS meter but I do have full confidence in my SPL meter to within a dB for frequencies between 200 Hz to 8 KHz and up to 125 dB. I have this confidence because I have verified a number of frequencies within this range and SPL against my buddy's $1.5K SPL meter. And yes, he's also right about the DVM as we've previously discussed. Randy, you have more work to do in this regard (should you choose to walk down this scary path ). In my mind, the verdict is still out as to whether or not you are sourcing 300W from the amp. But, look at the facts to date. You are telling us that you are achieving 100 dB with 10W. Look at what I posted. Granted, our rooms are different and I used a test tone and your RS meter may be wrong (which it might be but I would bet only by a dB). But, it's a place to start. If I had to put money down right now, I'd say you are nowhere close to 300W when you are shutting down at 106 dB.

Quote:

In any event, it will eliminate you major complaint.




Will it? I thought other listeners are experiencing shut-down with the clipper removed. They could be playing at absolutely ridiculous levels and over-heating the unit.

BTW, I still don't understand how they claim to be sourcing 700WRMS on the output with a 350VA toroid.

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#162538 - 04/04/07 07:41 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: Mojo]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
Updated measurements at 0 and +10:

amp.....Vac.....Z......Power.....SPL
-30......0.9....8.5......0.1.........75
-20..... 2.5....8.5......0.7.........84
-10..... 9.5....8.5......11..........92
..0.......30.....8.5......106.........95
+10......37.....???......???.........???

At 0, I still had what sounded to me like a pure tone. At +10, my amp was distorting badly. It's hard to say what frequencies exactly were going into the speaker. So it's meaningless to attempt to do any calculations with the gain at +10.

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#162539 - 04/04/07 08:20 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: michael_d]
real80sman Offline
connoisseur

Registered: 05/16/02
Posts: 1123
Loc: Ontario, Canada
mdrew, thanks for the clarification. I can only rely on my own experience with the 80's. I've driven them with a late 1980's Luxman 2ch integrated amp, and an early 2000's Yamaha 6.1 receiver.

With the Luxman, as I turned it up it would really sing. It stayed clean and controlled. Sounded awesome. Push it a little more and 'click' - off it went. Turn it back down, and within 10 seconds it was back on. It was NOT rated for 4ohms and when pushed, ran super hot. (Currently, it's driving my M3's in the office.)

With the Yamaha, when it's pushed things get nasty. The highs sound raw and really rough, and the bass is distorted. I've gotten it up to -8db, and I thought "Why?". I usually run it around -20db which is plenty loud enough for movies. (Lower when the family is around) But for music, at the levels I like to listen to, I NEED more power. (The area is ~12,000cuft) For most day to day listening, I'm happy with the Yamaha. It sounds great so long as it isn't pushed hard.

As a side note, the Yammy runs fairly warm, but has never shut down.



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#162540 - 04/04/07 09:36 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: bugbitten]
bugbitten Offline
connoisseur

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

Quote:

Quote:

How large are the toroids in the Outlaws spread across 5 or 7 channels? I know each amp on the mps-1 has its own 350VA Toroid or 2.45KVA total for 7 amps.




I'll have to find the size (I bet Gonk knows), but the 7500 and 7700 have the same 2 toroids. Must be big for the 7500 to weigh 80 lbs.




I still haven't found the sizes but Gonk has photos:

http://www.prillaman.net/outlaw_pics/ (about halfway down)




This from Scott at Outlaw:

Quote:

Transformer power ratings can vary dramatically because of a lack of standards in our industry. The "duty cycle" is what determines the VA rating because temperature rise has to be controlled. If you had a battery charger, the transformer has to handle 100% duty cycle because the power is delivered constantly. Not so in the case of audio power amplifiers. The duty cycle is less than 50% for music and even lower for most home theater applications. All transformers in Outlaw amplifiers can deliver whatever power is demanded by the loudspeaker load without fear of overheating or damage. For a home theater applications, because of the lower duty cycle, the transformers in these amplifiers could theoretically handle 4 thousand VA without overheating. Even though this is true, we use a much more conservative approach.


For the record, both the 7500 and the 7700 meet (actually exceed) their power ratings of 200 Watt per channel-all channels driven at .05% from 20 - 20 kHz (unlike some other manufacturers, we are not rating our amps at 1 kHz or are measuring our power at 1% distortion.)


Each of these amplifiers utilizes two transformers of varying "sizes" depending on how many channels they are asked to drive. Each transformer has a number (either two, three or four) of secondary windings so that each winding is dedicated to its' own channel. By our calculations, the 7500 transformers have a total of approximately 1.8kVa and the 7700 has about 2.05kVa.

Scott




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#162541 - 04/04/07 10:11 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10385
Randy, give the multimeter voltage measurements a try at the shut-down levels. Yes, it isn't the way that amplifier output is measured professionally; among other things fixed resistance into a set of resistors is used(rather than a speaker), the frequency is known, rather than variable as it is with music, and an oscilloscope is used to observe the point at which the wave form top flattens, indicating clipping. However, this "quick-and-dirty" measurement is often used to get a ball park number. Don't worry about refinements at this point; it'd be interesting to see the voltage numbers at very high sound levels.
_________________________
-----------------------------------

Enjoy the music, not the equipment.



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#162542 - 04/04/07 10:16 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: JohnK]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13333
Loc: Iowa
Hold your horses, almost done John....
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162543 - 04/05/07 11:25 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: bugbitten]
KlipschGuy Offline
old hand

Registered: 03/23/07
Posts: 79
Loc: Waterloo, On
hey Shawn , I agree about your findings. I also read here some where that Alan was having an Axiom party and had the M80's cranked pretty good with Dennon amps and guess what? They shut down! I think Axiom could speak up and let us know their thoughts on this issue, these speakers do seem to be more difficult to drive than is first seen, however, they sound awesome!

Chris
_________________________
Emotiva DMC1, MPS-1 ,M80v2 ,Klipsch RC64,Mirage Omni260 surrounds,Paradigm PW2200 sub

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