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#162394 - 03/24/07 12:34 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
Randy,

Compare the input voltage specification for the pre-amp input on the Emotiva to the output of the Denon. Are you perhaps saturating the Emotiva's input when you turn up the Denon's gain? This is a long shot but you never know.

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#162395 - 03/24/07 02:17 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Haoleb Offline
connoisseur

Registered: 09/25/02
Posts: 1488
Loc: Maine
Quote:

Thanks guys. Based on Gene's review at audioholics, he ran the MPS-1 at 120+ dB's for hours at a party he had for his columbian friends, and the MPS-1 didn't make a sweat. I really can't believe I'm overdriving it Rick?

The amp is in the lowest shelf of my AV rack with plenty of breathing room on top and back. The basement stays pretty cool year around.

I will recheck the wiring, but find that hard to believe as I'm very picky on my connections, but one should never assume.

Normally, I don't play music this loud, somewhere in the 90's is more than fine. With the efficiency of the 80's, it does not take much.

Also, keep in mind my room is 8100 Cubic Feet, so I have a lot of air to fill. From the primary movie seat I was fluctuating from 98-105 or so dB's during different passages of the music when having it really cranked up.





I just read this review since i thought 120db + seemed a bit excessive. Ive had my system going at 105db and that was LOUD, Louder than I would ever listen. I cant imagine anyone playing music at 120+db, And unless he was using some sort of club speakers even hitting those levels would be hard.

He actually said that the amp shutdown a few times during the course of the night at those levels.

Quote:

I estimated they were hitting SPL levels in excess of 120dB - at least until the MPS-1 went into protection mode and shut down. This happened a few times during the course of the evening and I was curious as to why, since I heard no signs of distress from the amp, even at these insane levels.



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#162396 - 03/24/07 12:32 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: Mojo]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13311
Loc: Iowa
I'm going to recheck my wiring today to make sure I don't have a strand or something touching, which I highly doubt. Last night I had a bunch of friends over and we watched to movie "The Marine". At some time during the movie the left amp shut down because after it was over I noticed the blue light turned red for that channel.

I was sitting clear over to the right side of the room in front of the right m80, so I didn't notice the left channel missing until I looked over at the amp.
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162397 - 03/24/07 12:52 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
bugbitten Offline
connoisseur

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

Are you still in the 30 day return window?

This just doesn't sound good.

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#162398 - 03/24/07 01:06 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: bugbitten]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13311
Loc: Iowa
Not sure, I can check.

I'm beginning to wonder if it is not the preout voltage of my Denon, which I think is 1.2v and possibly it is clipping at the fuller power to the MPS-1. Below is a portion of the audioholics review I found, which appears to worry about some AVR preouts may have potential problems:

"I measured the voltage gain of the MPS-1 via balanced and unbalanced inputs and found the following:

Unbalanced: Av = 27dB
Balanced: AV = 26dB
Typical THX Product
Unbalanced Av = 29dB
Balanced: Av = 23dB (6dB lower than balanced)
It's a standard practice in most consumer and pro audio equipment that the gain structure of unbalanced to balanced is about 6dB less for the latter for power amps. The preamp therefore usually has a +6dB boost via the balanced outputs to compensate. I was a bit puzzled that the MPS-1 didn't follow this convention. However I didn't find it to be much of an issue, especially since the balanced outputs were about 3dB hotter than convention. It took about 1.65Vrms to drive the MPS-1 to full power. Had the MPS-1 followed standard convention of Av = 23dB some preamp sections of receivers such as the Yamaha RX-V2500 may not have been able to drive it to full power since that receivers' preamp outputs clip when output signals exceed 2Vrms. My personal criteria for amplifier gain structure is that it should be able to hit full power when driven with 2-3Vrms. The MPS-1 fell well within this criteria."


There is another guy on AVSforum that is having a similar problem with his Denon 2807 and his 4ohm Ref 1's.

I am not a electronics expert, but could this voltage thing be playing a part, or could it be my 4ohm 80's causing the problem?
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162399 - 03/24/07 06:32 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
According to the manual, the Denon's pre-amp out is 1.2V. And according to the Audioholics review you posted, the MPS-1 should be good to at least 2V. So I now doubt that's the problem. Your speaker impedance does not affect the Denon at all since it's buffered by the MPS-1. You may want to check your speaker to see if it is damaged. If your Ohm meter reads less than 2 Ohms, that's probably your problem. If you don't have a meter, connect the speakers directly to the Denon.

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#162400 - 03/24/07 09:19 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10309
Randy, first a comment on what Gene said about the gain. When a balanced connection with two wires carrying signals into the amp(instead of the one with a regular coaxial cable)is used, the two voltages combine for a 6dB increase(a voltage double is 6dB, compared to the 3dB increase for a power double). That's why, as Gene pointed out, that the gain for the balanced input is typically designed to be 6dB lower, to keep things even regardless of whether a balanced or unbalanced input is used. The Emotiva's higher gain is an interesting curiosity, but as Gene commented, it isn't of any particular significance. The gain on the unbalanced input(which you're using)is a typical number which the 2805 can surely provide enough voltage to satisfy, and even if it couldn't, the result would be distortion in the preamp, not the amp shutting down.

Yes, re-do the connections even if they look good, because those little wires can be very sneaky, and they seem to cause trouble a lot more often than the amp actually being driven too hard does. As I commented, the 6dB with doubling of distance number isn't adequate for a complete picture of power use and the dB numbers you give shouldn't cause a problem with the M80s which are "an easy 4 ohm load". I recall you mentioning when you got the M80s how your 2805 made them "sing", and it wouldn't be surprising if it still does if you connect it to the M80s to check for a shutoff(unless an internal short has developed in one of the M80s).

Despite the assurances that you've received, there may be something wrong with the Emotiva.
_________________________
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Enjoy the music, not the equipment.



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#162401 - 03/24/07 09:44 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: JohnK]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13311
Loc: Iowa
Thanks Mojo and John

I'm pretty sure there is nothing wrong with my new m80's they sound great. I'm now thinking there most likely is nothing wrong with the mps-1 either. I re-checked all the speaker connections and everything was fine.

Today, I hooked my Denon back up to my m80's. I picked 4-5 different CD's, everything from Classical, Josh Groban, Jazz, and some good ole rock and roll.

I re-checked my calibration of all speakers using the Denon's test tones and noticed I was running them about 1dB to high, no big deal really, anyway they are now at +4dB for an SPL of 75dB on the meter.

From 13ft away, with the Denon main volume on 0dB, that gave me an average of 100dB (peaks upto 105dB or so) on the SPL meter. As I tested various songs, and gradually raised the volume, I noticed the sound from the Denon, although still good, did appear to be straining a little at the higher levels and seemed to be less detailed and harsher to my ears. With the SPL meter now set to 110dB range and the volume turned up to around +5to6 I was seeing peaks going beyond 110dB on the meter. If I do my math correctly, this was really working the Denon, and I could tell by the sound, I was most likely approaching its limits and headroom was gone.

With the mps-1 hooked back up, things seemed much different. The same songs never showed any strain at any levels. I never cranked the volume all the way to the max like the other day, but even at +6-10 on the Denon the mps-1 had no problems, was not even warm to the touch, and the fans never came on once.

I'll keep an eye on things, and most likely will never have a need to turn the Denon volume to its max, that is just to loud.
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#162402 - 03/25/07 11:06 AM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: SirQuack]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 3292
I'm glad to hear your speakers are healthy. You are suggesting that perhaps the Denon is being taxed when you turn up the gain. I can understand your Denon getting taxed when connected to the speakers but it should not be getting taxed when it's connected to the MPS-1. The MPS-1 should have a very high input impedance (>100KOhms with very small capacitance in the order of hundreds of pF or less). But even if the Denon is being burdened, this still doesn't explain why the MPS-1 is shutting down. I don't mean to scare you but I strongly suggest you don't over-look this. You may have discovered a marginal design and/or marginal components that could get worse with use. And it could come back to haunt you after the warranty has expired. Along these lines, find out how Emotiva burns this product in and whether or not the burn-in covers this sub-system.

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#162403 - 03/25/07 04:43 PM Re: Emotiva MPS-1 shutting down? Amp gurus help [Re: Mojo]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13311
Loc: Iowa
Thanks mojo for your concern. Emotiva is like Axiom, in that they care about their customers and will do whatever it takes to fix any issues. I don't think your familiar with their company.

Here is a bit of history, they are a Engineering and Design company that has been around for many years designing the guts/electronics used in many of the high end ($$$$$$) amp companies on the market. I won't disclose any of those names per my promise to them, however, they are under confidential agreements with those companies, and in return they were able to make their own product, using the same insides they designed for others.

Anyway, I know many people using their products on AV123 and AVSforum that are highly regarded in the AV community, and they give high praise.

In fact, I had a small issue with my amps voltage regulators when I first purchased the mono's, and they shipped me two modified amps within 2 days that were personally lab tested by the owner to make sure my problem would be resolved, and it was.

I do appreciate your concern and advice though...Randy
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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