# Amplifier Questions and thoughts.



## bambino (Feb 21, 2010)

Story: So as many of you know i have more amplifiers then any one person should be able to own legally (2 Emotiva UPA-5's, XPA-5, 2- XPA-1's, 4 Crown XLS805's, and 2 Dayton HPSA 1000's) any how needless to say i do not have rack space for all of them so i let my brother in-law use them, test them, brake them in whatever. Well last night i brought over his next amp to run through it's paces, he had been running in my XPA-5 we exchanged it for one of my UPA-5's but before we did the switch we listend to the XPA-5 to compare sounds then we hooked up the UPA-5 what a differance in sound it was, it sounded louder and cleaner i thought:scratch:that is strange the XPA has twice the power as the UPA, then he informed me that the XPA would shut down if we cranked it to the volume we had the UPA at, that i thought was really strange.
He has a Marantz AVR with Paradigm Monitor 9's for the fronts which all we did and he does is 2 channel music listening. 
My question is or does anybody have any thoughts as to why XPA was shutting down when pushed for long periods and the UPA does not? My theory is that the XPA shut down to protect itself from over current but really would that happen? I do recall when he had a Denon AVR and smaller speakers the thing would shut down all the time and the AVR was no slouch then he got the bigger speakers and never had a shut down issue. Like i said he has since moved to a Marantz AVR and had no shut down problems with just using internal amplification.

Anyhow thanks for reading the long drawn out post and if anyone has any theorys as to why please shoot them my way this has me curious. Thanks, Bambino.:T


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## digital desire (Dec 17, 2006)

I crank my XPA-5 to ear bleed levels with some pretty in-efficient diy 4ohm speakers (WWMT's). Never a problem, and had some pretty serious parties with heavy metal freaks that love concert DVD's. 

Me thinks you need to send the XPA-5 back for a physical!


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## Jungle Jack (Jul 28, 2009)

Hello,
I agree with the above Poster. While the XPA-5 does not have a huge power supply 1.2 (kVA) which is the same used in the XPA-2, it is still far more powerful than the UPA-5.
Cheers,
JJ


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## bambino (Feb 21, 2010)

I spoke with Emotiva today and he mentiond that the speakers may be too inefficiant for the amp, i find that hard to believe especially being that they are Paradigm Monitor 9's (very efficiant). I'll be brining the XPA-5 to my house this week to run some tests and see if i have a problem, i have to wait untill the twins go to grandma and grandpas.
The thing strange about it all is that while it was hooked up to his rig i thought it sounded good and it never shut down but when i hooked up the smaller UPA-5 there was a huge sonic differance all the way around in a good way in terms of volume, highs and bass impact.:scratch:


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## vann_d (Apr 7, 2009)

I remember reading a review of the upa-7 at audioholics. Something about more real world capacitance than the xpa-5. Maybe upa-5 has the same advantage.

Were you running stereo or muli-channel?


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## bambino (Feb 21, 2010)

2-channel stereo.


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## vann_d (Apr 7, 2009)

From http://www.audioholics.com/reviews/amplifiers/emotiva-upa-7/upa7-introduction

"The UPA-7 is a traditional class A/B amplifier design utilizing a single larger toroidal power transformer and large capacitance bank for its power supply. I much prefer this over smaller individual power supplies for each channel much like Emotiva used to do with their MPS-1 and MPS-2 amplifiers. Having a singular larger sized power supply allows the amplifier to deliver more power to any given channel if the output devices can handle it. This in turn provides more available headroom which is critical for effortlessly producing large dynamics and peaks in music and movies. Emotiva claims the UPA-7 has 90,000uF total power supply capacitance. Since the UPA-7 is only rated at 125 watts / channel (8-ohms), they could get by with using lower V rated parts which greatly reduces their profile. Thus Emotiva employed six 15,000uF capacitors wired in parallel to yield 90,000uF. In some of their prior amplifier designs, (ie. MPS-1, XPA-2), Emotiva implemented series-parallel 50V capacitor banks which allowed them to use smaller parts while still having 100V capability to handle the higher power output levels. The problem with this method is you now have reduced the total available capacitance to 1/4th the sum of the parts. In the case of their XPA2, which if you added up all the power supply capacitors came out to 180,000uF, the actual real capacitance available was only 45,000uF. In reality, the UPA-7 has more available power supply capacitance than all of their current XPA series amplifiers. Incidentally, the UPA-7 is also Emotiva's only seven channel amplifier currently available. What lots of capacitance does in a power supply for an amplifier is reduce ripple, and increase available reserves to allow more sustained power with less fluctuations under heavy demand. "

Go figure, huh? :dunno:


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## vann_d (Apr 7, 2009)

Using the same logic the UPA-5 would still have greater capacitance. If the logic is correct, maybe this explains things.

Me thinks the XPA-series wins when it comes to multichannel playback...


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## Jungle Jack (Jul 28, 2009)

Hello,
That is interesting. The XPA-5 has 60,000uf of Filter Capacitance. If the UPA-5 uses the same Capacitor Banks as the UPA-7, that might be the culprit.

While some are reticent to buy used, I still think the Parasound HCA-2205AT is one of the best 5 Channel Amplifiers for the money on the market. It is almost identical to the 4500 Dollar Halo A51. The differences are the A51 uses a 2.2 kVA Transformer and 164,000uf Capacitance whereas the 2205 uses a 2.0 kVA Transformer and 150,000uf of Capacitance. In other words, the 2205 has almost twice as large of a Toroidal Transformer and almost 3 times the amount of Capacitance. 

The beauty of the 2205 is they are available for under 1200 Dollars with many being available for a grand. While used, back then Parasound offered a 10 year Warranty on Amplifiers and the Components in the Amplifier are built to last. This is a big reason why they are not often available on the Used Market and when they are sell quickly.
Cheers,
JJ


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## digital desire (Dec 17, 2006)

I maintain what I said before. As an xpa-5 owner, I can emphatically state that there is something wrong with your xpa-5. There is no way, no how, it should be out performed by the upa7, _especially_ in two channel use. 
Something is wrong.
Capacitance is great and all, but the transformer in the xpa is significantly bigger, and it is always better to have a bigger generator than a bigger battery.


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## vann_d (Apr 7, 2009)

digital desire said:


> I maintain what I said before. As an xpa-5 owner, I can emphatically state that there is something wrong with your xpa-5. There is no way, no how, it should be out performed by the upa7, especially in two channel use.
> Something is wrong.
> Capacitance is great and all, but the transformer in the xpa is significantly bigger, and it is always better to have a bigger generator than a bigger battery.


Yeah, I'm sure you're right. I don't know enough about how the amplifiers work to argue. I was just digging for some possible explaination that was better than "your speakers are too inefficient". This was a slightly rediculous explanation by emotiva. Kinda erks me when I hear of people getting poor answers from the manufacturer.


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## bambino (Feb 21, 2010)

Like i said in my previous post i'll find out later this week when the twins are gone, i'll hook it up and put it through it's paces like never before. I'll first do 2-channel then move on to 5-channel stereo (all music) then we'll see.
Also i think i posted in my first post about how my brother in-law had a nice Denon and some smaller speakers and it too would shut down when played loudly for a period. The salesman at the store also said basically the same thing as Emotiva is that it needs larger speakers to drive. Thats one statement i don't understand.:scratch:


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## digital desire (Dec 17, 2006)

One of the toughest speakers to drive is the ML planer speakers. The XPA can drive those fine. My DIY WWMT's drop close to 3 ohms, and they are driven fine also.


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## bambino (Feb 21, 2010)

digital desire said:


> I maintain what I said before. As an xpa-5 owner, I can emphatically state that there is something wrong with your xpa-5. There is no way, no how, it should be out performed by the upa7, _especially_ in two channel use.
> Something is wrong.
> Capacitance is great and all, but the transformer in the xpa is significantly bigger, and it is always better to have a bigger generator than a bigger battery.


There is no way to tell untill i get it here to test it myself. It's also not being out performed by the UPA-7 it's the UPA-5, and not that it's being out done by it, it just sounds better and goes louder. It could also be do to the way my brother in-law had it setup:dontknow:. I'll post my findings tomorrow and see what I come up with.:T


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## bambino (Feb 21, 2010)

Well tomorrow turned into 2 weeks but i got the amp hooked up and was able to put it through it's paces for a good 1/2hr or so. During that time it got very warm but never shut down and remember i am driving larger speakers then on the setup it was on before, so my conclusion to this is that the smaller speakers presented a load on the amp that it did not prefer at high volume for extended periods, i would say it was the amps circuitry protecting itself from crazy peaks in current and impedance.
I know it does not sound right but thats my theory, i would like to know what anybody else with knowledge of amps and speaker loads think. Thanks, Bambino.:T

Oh, and i really do not think anything is wrong with the amp. (i hope)


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## Jungle Jack (Jul 28, 2009)

Hello,
It could have even been AC issues at your Brother In Laws that caused the XPA-5 to underperform. There is no doubt the XPA-5 is the more powerful Amplifier. Gremlins perhaps...
JJ


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## bambino (Feb 21, 2010)

Jungle Jack said:


> Hello,
> It could have even been AC issues at your Brother In Laws that caused the XPA-5 to underperform. There is no doubt the XPA-5 is the more powerful Amplifier. Gremlins perhaps...
> JJ


Those are some of my thoughts as well, i was reading a few different posts about how the amps are setup with undercurrent, overcurrent and spike protection.

An analogy might be: using too small of an extention chord for power tools can damage them because of lack of current they are trying to draw or there is a saying but i've probly got it wrong "like trying to feed a fire hose through a funnel" (something like that). Anyhow, i do think that one of the above is the answer if not i'll keep this thread updated.:T


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## bambino (Feb 21, 2010)

Gotta throw this in this thread as well. I hooked my other amp a UPA-5, there certainly is a sound quality differance between the 2 lines of amps: The XPA's seem to be fuller sounding all around (treble/bass) where as the UPA seems to lack in the bass department but does a swell job in the mid to high range frequencies. 
These are just my findings and opinions but overall both are fine amps but i do think the XPA's knock the socks off the UPA's (for obvious reasons though).:T


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## Mike Ronesia (Dec 4, 2008)

Good to hear the problem is with your brother in-law :dumbcrazy: and not the amp.


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## bambino (Feb 21, 2010)

I really believe it to be a lack of current issue. I know that another poster on this thread had mentiond his XPA-5 to be able to drive a very inefficiant load so i must point this out: I have an XPA-1 on each of my Paradigm Monitor 11's which are fairly simple speakers to drive but when party time comes the led's are pegged and the amps are good and warm not just breaking a sweat like alot of other folks have mentiond. So does that mean i have 5 bad Emotiva amps? I think not, it's the current that the amps aren't getting which isn't good for any electronic device to starve it of power.:T


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