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Re: XPA 2 Now! A Keeper?
myrison #227208 10/28/08 12:03 AM
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SatKartr,

You shouldn't have to be fooling with crossover settings to see if it helps at this point. That beefy amp you have should Not be shutting down. My advice is to look into getting a replacement, so you'll know for sure whether you've got a bum amp.


Epic 80 / SVS PB13 Ultra
Denon 3805 / M2200 Outlaw Monos /
Sammy 55" LED
Re: XPA 2 Now! A Keeper?
myrison #227209 10/28/08 12:04 AM
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That's the next test actually and your logic actually makes perfect sense. I'm curious to see what kind of SPLs I can get out of the Yamaha, I just picked it up as a bookmark until I can decide exactly what pre/pro I want to go with.

I suspect maybe Lonnie is acting so lackadaisical since he went through all of this with Randy and the MPS-1 so now he may have a defeatist attitude regarding the M80s. It also seems funny because the MPS-1 is rated at 300 wpc into 4 ohms versus the xpa2 with 500 wpc into 4 ohms, so I wonder how the protect circuit works such that I can't even generate 90-100 dbls during HT, that surprises me.


"If you try to turn toward it, you go against it."
Re: XPA 2 Now! A Keeper?
SatKartr #227227 10/28/08 02:11 AM
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I'll be interested to hear what you think about how the Yammy drives them. Please let us know.

By the way, is the family back yet or are you still off the leash? ;\)

Jason


Epic 80-800: HG Cherry
Re: XPA 2 Now! A Keeper?
myrison #227229 10/28/08 02:16 AM
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They arrived a few hours ago, so the leash is back, well I suppose someone has to keep me in line.


"If you try to turn toward it, you go against it."
Re: XPA 2 Now! A Keeper?
SatKartr #227239 10/28/08 02:59 AM
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Well Sat, as I commented before, the Emotiva remains a mystery to me. There were all sorts of discussions of measurement procedures both on the board and in PMs when Randy was investigating the problem. The resulting numbers weren't anything that should shut down even the typical modestly-priced receiver rated in the 100 watt area.

Protection circuits(besides eventually operating when the temperature would get too high)first operate when the measured current is out of line with the voltage being supplied at the time. One form of Ohm's Law is I=E/R, and if the measured current is some big number in relation to the voltage, that can only be because the resistance has become very low(i.e., a short somewhere in the wiring), and the circuits will immediately shut things down. Power supply sections are limited as to the maximum voltage that they can supply, and since power is the product of voltage times current, if not enough voltage is available for a given amount of power the current would have to increase so that the power equation is satisfied. This increased current measurement again would cause the protective circuits to shut down.

How all this seems to be a problem with the Emotiva/M80 combination at not extremely high sound levels remains unclear. I would be inclined to view the shut-downs as simply being God's way of telling you not to use that amplifier.


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Enjoy the music, not the equipment.


Re: XPA 2 Now! A Keeper?
JohnK #227243 10/28/08 03:08 AM
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 Quote:
I would be inclined to view the shut-downs as simply being God's way of telling you not to use that amplifier.


I have a feeling this chapter is removed from most electrical engineering textbooks. . .


***********
"Nothin' up my sleeve. . ." --Bullwinkle J. Moose
Re: XPA 2 Now! A Keeper?
JohnK #227247 10/28/08 03:33 AM
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I think I'm beginning to hear the Big Guy loud and clear. \:D

What surprised me about all this was that Randy had problems with the MPS-1 but others with the RPA and XPA architecture have not had problems pairing the M80s with Emotiva.

Your post has piqued my curiosity though, you state, "if the measured current is some big number in relation to the voltage," are there any standard examples of what a large amperage would be or is it all relative? It seems like the amplifier is going into protect when the current goes up to around 6 amps above baseline (it shuts down when amperage reaches 10-13 amps for all devices connected to the HT electrical circuit with 4-6 amps being the reading when the HT system is on but idling), that level does not seem that extreme to me, but I have no sense of what might be the normal rage.

I was hoping for a long term solution, i.e., headroom for any conceivable situation including even if we moved and our HT was in a bigger space, looks like it's time to search for a Plan B.


"If you try to turn toward it, you go against it."
Re: XPA 2 Now! A Keeper?
SatKartr #227259 10/28/08 04:05 AM
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If I recall, Lonnie told me the MPS-1 had a "waveform limiter" circuit that was protecting the amp. I don't believe the other amps, or current designs have this circuit, not sure.

Lonnie provided great support and customer service during the 3 months I tried the amp. However, I just could not grasp the feedback saying it was the 80's, or I was driving the amp to its design limits. The 80's are very easy to drive, efficient speakers, that don't fall below 4ohms across the FR.

Something just was not right in my case where an amp with seperate monoblocks with those specs should even flinch. Now the Denon did show some signs of a clipping at +10 to +15 but never shut down. The MPS-1 sounded fantastic with no hint of clipping at all, however it would just shut off for no apparant reason.

My current Odyssey monoblocks (based on German Symphonic Line engineering) A/AB just keep going and going an going. \:\)


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: XPA 2 Now! A Keeper?
SirQuack #227285 10/28/08 01:49 PM
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Sat, when you're rocking out on the XPA-2, at the point it's cutting out, what are the status LED meters doing? Are they pegged at the far the ends of the scale? I'm just curious if you can tell that the amp is being stressed (pegged-meters) or if it's cutting out early.

For the EE guys, is there any way that Sat could hook up an ohm meter to his system to monitor the resistance when the XPA cuts out? It seems that would answer the whole question. <4ohm = M80 problem, >= 4ohm = XPA problem.

The bizarre thing here is that the folks at Emotiva can build an amp that works. They know how to do it. As I've said, I have no problems with my LPA-1 + M80 combo at these 100db+ 'reference' levels we're talking about. None at all. And there are several others around here with the same setup. And the LPA-1 is/was their cheap amp.

But it makes no sense to me that their flagship multichannel MPS-1 and their top-end stereo XPA-2 can't drive M80's. It was absurd when Randy went through this, and it's still absurd that Sat is having the same problem. Since Emotiva claims the M80's are the problem, I'd love to see that data. They need to explain *why* the M80's seem to break some of their amps.

But from a troubleshooting perspective, I can see where Lonnie is coming from. It's still not the best response but I understand it. Since you changed speakers (were the Polks 4-ohm too?) and the XPA worked, then that points to the "problem" being the M80's. That "problem" is easily solved by getting your money back for the XPA and getting a different amp. ;\)

Either we're discovering that some M80's have an unusual impedance dip that's too much for their amps, or we're finding that some Emotiva amps aren't meeting their published specs with respect to 4-ohm speakers.

Last edited by PeterChenoweth; 10/28/08 02:13 PM.

M80v2 | VP150v2 | QS8v2
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Re: XPA 2 Now! A Keeper?
PeterChenoweth #227289 10/28/08 02:41 PM
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Thanks for the ideas, I will check out the LED thing, the amp is sort of off to the side and turned sideways so I have not monitored what the leds are doing when the amp cuts out, I will obviously have to do that (smacks forehead).

I did email Lonnie back yesterday that the speaker comparison was inaccurate because the Polks are 6 ohm speakers, he has not responded back yet.

The ohm meter idea also sounds promising if there's some practical way to hook it up, I will look into it.


"If you try to turn toward it, you go against it."
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