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Receiver or separate amp with 4 ohm speakers


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#1 of 22 OFFLINE   Rick Westfall

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Posted June 26 2010 - 04:40 PM

I currently have a Denon 2807 which does good work with my current speakers.  I'm looking to upgrade speakers which might mean 4 ohm speakers.  I'm not sure that the 2807 will drive these well.  So I'm thinking about finding a three channel amp for the mains and center and letting the Denon drive the sides and rears.  First, will that work and second what are your recommendations for the three channel amp.  I was looking at the Emotiva but I just started and would love any advice. Thanks Rick

#2 of 22 OFFLINE   John Garcia

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Posted June 28 2010 - 10:26 AM

Few receivers can truly handle 4 Ohm speakers well.  I have a pretty hefty Marantz and moving to external amplification for the front 3 made a very noticeable difference at elevated levels.  All 5 of my speakers are 4Ohm though, and in both instances where I had this setup, the rooms were/are quite large.  If you had a medium room with only one pair that were 4 ohm, your receiver can probably handle it.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#3 of 22 OFFLINE   JohnRice

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Posted June 28 2010 - 04:30 PM

Does the 2807 have pre-amp outputs?  The current model (2810) does not.  If it doesn't have them, it's pretty much a moot point, since you can't use an external amp without them, unless you upgrade the receiver or go with separates.  The problem is, basically all home theater receivers use Class D amps, which have difficulty with low impedance speakers.  Manufacturers and plenty of people will tell you otherwise, but it's just the way it is.  Going to a 3 channel amp is a good idea.  Actually, it is always a good idea.  You can't have too much power and the front is the most important. Coincidentally, I just bought an Emotiva XPA-5 to power all the channels except L/R.  It just arrived today.  I have already used an external amp for L/R because my speakers are not only 4 ohm (probably lower, if you can believe it) but also have low sensitivity.  So far, it seems quite good, especially for the price. So, it hinges on the receiver.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#4 of 22 OFFLINE   Rick Westfall

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Posted June 29 2010 - 01:00 AM

Yes, it does have the pre-outs.  I'm leaning heavily to the Emotiva until I hear from someone that directs me somewhere else.

#5 of 22 OFFLINE   JohnRice

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Posted June 29 2010 - 02:07 AM

I gave the Emotiva XPA-5 a bit of a workout once it arrived yesterday.  It seems like a great deal.  I just hope you realize how enormous those amps are.  It takes some planning. When I decided to get this amp I considered just getting a 3 channel, but the XPA-5, right now, is only $180 more than the XPA-3 and even if one or two channels are idle, that is such a small price increase and it leaves more power supply available for the other channels.  I probably will eventually go at least to 6.1 and use at least 4 of the channels. Having said that, another approach you might consider is to get a UPA-5 for all channels right now, $494 on sale, then if you get power hungry, get a 2 or 3 channel XPA later.  There is nothing wrong with leaving a channel idle on an amp, since at the least it lowers the demands on the power supply and the Emotiva prices are so low anyway. I have never had this much power for surrounds and I think, when I really crank up an action movie, it actually needs it.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#6 of 22 OFFLINE   Rick Westfall

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Posted June 29 2010 - 05:34 AM

Well thanks for giving me one more thing to think about :).  I'm running 7.1 right now so I'm not sure about buying a 5 channel amp when that won't completely cover me.  I guess I need to do some research on the difference between xpa and upa amps. Thanks again for the advice!

#7 of 22 OFFLINE   JohnRice

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Posted June 29 2010 - 06:12 AM

The difference is in both power and possible refinement of the sound.  Also take into consideration how much A/C power you have available.  If you are going to run all 7 channels with 2 amps, you need to connect them to two different circuits or you will just be strangling their capability.  That is also one advantage of having two amps.  Notice there is not an XPA-7.  That is because a 15 amp circuit would not be enough to power it.  I often see people saying they are running more than one of these on a single circuit with no problem, but they just don't realize they are suffocating the amp.  They think if the circuit breaker doesn't trip, everything is fine.  The problem is, it takes several seconds (like 10-20 seconds) of overload to trip a circuit breaker.  The power an amp draws fluctuates constantly and it is unlikely it will overload the circuit long enough to trip it. So, you could use a UPA-5 to run the 4 surround channels and an XPA-3 to run the front.  Just a thought.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#8 of 22 OFFLINE   JohnRice

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Posted June 29 2010 - 06:15 AM

BTW, something worth pointing out is that power isn't so much about playing louder, as it is about being able to play loud more effortlessly, as in, more cleanly.  If you think a more powerful amp means playing much louder than you can now, you will probably be disappointed.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#9 of 22 OFFLINE   Rick Westfall

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Posted June 29 2010 - 10:34 AM

Thanks for this info.  I'm not looking for more loud.  going for better sound, not louder sound.  Also, now you have me on another goose chase with the multiple circuit issue.  So plugging into a monster power center won't help?  Oh the joy of HT

#10 of 22 OFFLINE   JohnRice

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Posted June 29 2010 - 05:47 PM

Nope, the power center won't generate more power.  How much electricity is available is something people like to overlook, but the power has to come from somewhere.  For example, the power supply in the XPA-1, XPA-2 and XPA-5 is capable of drawing 10 amps.  A standard circuit is 15 amps.  So, if you connect two of those to the same circuit, there isn't enough available juice to run them both at full power.  The UPA-5 can draw 5 amps.  That is the core of the difference in power ratings, though there are other differences that can, theoretically, make the XPA produce better sound. It's not quite that simple, since amps do not draw power at the same rate all the time.  That also brings up an issue with power centers.  Many are NOT good for amps for that exact reason.  You should not use a power center with an amp (or receiver) unless it has high current outlets marked specifically for amps.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#11 of 22 OFFLINE   John Garcia

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Posted June 30 2010 - 09:08 AM

I have my XPA-3 plugged into my Panamax because the nearest separate circuit has too many other things on it as it is wired to other rooms (found this out the hard way).  I asked Emotiva about this and they said it isn't an issue, though I do have it plugged into the high current outlet. A good amp won't make your sound "better" it will make your speakers play at the best of their capability.  If you are looking for better sound, you will need to go listen to speakers because they make the single largest difference in sound.  An amp with sufficient power will allow you to play your system at higher levels without strain (and that is important when you are listening loud) but the sound will still be the same just louder.  In other words, an amp won't "transform" your sound into something it isn't.  If the system is struggling at the levels you are looking for, then the improvement might be quite noticeable.  If it isn't, then adding an amp might not make much of a difference at all, or at least not the kind of difference many people expect.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#12 of 22 OFFLINE   Rick Westfall

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Posted June 30 2010 - 09:40 AM

John, Thanks.  This "transformation" into an amp surrounded around the fact that I'm looking to upgrade the front three speakers and which more than likely will be 4 ohm speakers.  The Denon 2807 might drive them fine, but having the knowledge of the amp will give me a solution in the event I need one. Thanks for the info.  I'm continuing to gain more and more knowledge. Rick

#13 of 22 OFFLINE   JohnRice

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Posted June 30 2010 - 10:31 AM

Yeah, John is right on both issues.  You can use a power center, just make certain you plug amps and receivers into a high current outlet.  If the power center doesn't have one, it's better you not use it for those components.  The XPA-3 has a 7 amp power supply, so it isn't as big a consideration.  You should just keep it all in mind and look at the potential draw of all the high power components.


Again, like John said, a better amp is more an issue of fine tuning.  It won't transform the system, it can just make it sound better, but it can also make no discernible difference at all.  I think there is a big placebo factor.  You spend a bunch of money on more power, so you hear an improvement.


The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#14 of 22 OFFLINE   Rick Westfall

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Posted June 30 2010 - 01:03 PM

I think my first purchase will be the front three speakers (still trying to figure that out) and a new sub.  Once all is installed, I'll make a determination if a three channel amp is needed.  If the Denon 2807 can't push them, I'll probably give the Emotiva a spin.  Thanks for all your help!  Now I just need to figure out what speakers I'll need (want).  I think I have pretty much settled on the SVS for a sub (PB-13 Ultra).  Now...getting a 150+ lb sub upstairs into the HT room...a whole new problem.  

#15 of 22 OFFLINE   JohnRice

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Posted June 30 2010 - 01:27 PM

Rick, that is the best approach.  The Denon will drive the speakers, just not as well as the more expensive alternative.  That's a big reason it is more expensive.


The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#16 of 22 OFFLINE   Patrick Sun

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Posted October 11 2010 - 05:06 AM

Anyone have experience with the Emotiva UPA-5 amp?  With it being on sale for $399 (free shipping in continental US), I'm giving it serious consideration for an amp upgrade.
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#17 of 22 OFFLINE   JohnRice

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Posted October 11 2010 - 05:36 AM

I have the XPA-5, which is essentially the same, just with more power.  It is a nice amp.  It's enormous, so be sure you have room.  It's a great deal, but be aware that their amps all seem to have a bit of a quality control issue with the LEDs.  Only 4 of them on mine light up and after some research, things like that appear to be all too common.  The amp works fine, since the LEDs are just decoration.  What annoyed me is that the amp is SO heavy, the box is half destroyed by the time it arrives, then I haul it down the stairs, get it opened and lugged into place, turn it on and after a few minutes this stupid little fault shows up.  Of course, they will fix it, but it is a monumental task on my part to get that done, even though there is no cost.  Of course, the UPA-5 is not quite as heavy, but it is no lightweight. No matter how far digital amps have come, I still believe that traditional amps are capable of better sound, so long as the speakers are capable of reproducing the difference.  The XPA-5 definitely was an improvement over the Pioneer VSX-56txi that was powering my center and surrounds.  I already used an external amp for L&R. $400 for the UPA-5 is a hell of a deal.  I just wanted to warn you about the common LED problem.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.


#18 of 22 OFFLINE   Patrick Sun

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Posted October 11 2010 - 07:10 AM

Thanks for the info.  It's not like I even need that much power, but the price point is pretty good.  My 10-year old HK PA5800 was more than enough for my use, and it has almost half the rated power of the UPA-5, but the HK has lost a couple of its channels, so I'm currently surround-less.  I just wish I knew the supply/price would be around in a month or so, when some financial uncertainty in my life would be resolved.
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
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#19 of 22 OFFLINE   John Garcia

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Posted October 12 2010 - 06:08 AM

I have the XPA-3 and I am extremely happy with it.  I had an issue right out of the box with one of the RCAs being loose on the back and they paid shipping for me to return it and replaced it with another unit the same week.  No, they aren't a huge volume manufacturer, but they are a solid ID company and I have no problem recommending them.  That price won't be around for long, I'd suspect, though that doesn't mean there won't be a similar sale around Thanksgiving or Christmas, since they do tend to have good holiday deals, so that is something to think about.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#20 of 22 OFFLINE   JohnRice

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Posted October 12 2010 - 06:47 AM

I think John reinforced the idea that their quality control has problems, but the gear is quite good.  If they get that quality control in line, they could really take off.

The Hybrid System

The Music Part: Emotiva XSP-1, Thiel CS 3.6, Emotiva XPA-2, Marantz SA8004, Emotiva ERC-3, SVS PB-12 Plus 2

The Surround Part: Sherbourn PT-7030, Thiel SCS3, Emotiva XPA-5, Polk & Emotiva Surrounds.





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