Axiom Home Page Forums General Discussion Home Theater What to expect from poweramp

Since I'm coming out of my 7 year stagnation hiatus and upgrading my equipment again, and the sub is taken care of now, Im thinking about going the power amp/ processor route (XPA5, UMC-1 are candidates) to replace my older (but trusty as hell) Marantz SR7400.

My questions is what can be expected from giving my axioms much more power , doing the equation I found somewhere, my power is about 70 watts all channels driven in 5.1 now (105W x 7 from Marantz) The lower model UPA5 is 125 watts all channels driven (55 watt per channel increase) while the XPA5 is yet 200W all channels. Does this really bring speakers to life, help the dynamics? Besides the obvious of getting higher, distortion free output, I'm curious how I will hear the difference.

Another plus is I can get lossless through HDMI, not the analogs Im using now. Im having some real bass management issues going the uncompressed analog route unfortunately.

I went from a cheap Sony, rated at 100wpc to a Pioneer Elite, rated at 110wpc and the difference was like night and day. So, I don't think the wattage ratting had a lot to do with it. From what I've been seeing so far, perhaps it's the power supply that is more meaningful, but I don't know how those are rated.

What equation? I would be surprised if the 7400 wasn't capable of 105W/ch all driven. I did find a review that states Marantz rated it with all channels driven:

http://www.goodgearguide.com.au/review/home_entertainment/marantz/sr-7400/221579#cb

I think to see, well....., hear any increase in SQ you would need to go with the XPA5. The minor increase in output from the 7400 to the UPA would yield minimal if any SQ benefits. The XPA5 should yield 1-2 db louder playback and be all that much cleaner/clearer while doing it.

i have 2 krell amps and a krell processor powering my living room system, each channel is rated for 250w at 8ohm and 500w at 4 ohm... m60's and a vp150

did it make the system sound "better"? hrm. not really.... but they take balanced inputs from my processor, so there is ABSOLUTELY 0 hiss ever. even if the sound is turned to 0, there is no hiss. i think this is the biggest benefit of having the amps. besides the fact that they can give the speakers more power than they would EVER want. I have a Marantz mm9000 in my bedroom right now, and that amp uses RCA inputs, and i do get some hiss though that amp depending on the source. I use the cable music channels quite a bit, and in the living room with the Krells, there is no hiss, the audio is cleaned up by the processor and then fed to the amps.. in my bed room i have a NAD processor, and with the Marantz amp, i will get some hiss on the exact same channel.


i got my krell gear used, 2k$ for the processor ht 7.1 and about 1500$ each for the amps. the amps i got are the KAV 250a and the KAV 250a/3


i don't know how you feel about buying pre-owned stuff, but both of my amps were recently serviced and had the documentation to show what was done, and how many transistors were replaced.


another options is the Marantz MM9000 it does 160W X5 i've had mine for almost 6 years now, and still use it almost on a daily basis..


hope some of my rambling helps.

The difference between 105watts and 200 watts is less than 3dB at reference. Will it bring them to life, they aren't already? Help with dynamics, not really. Yeah, you might gain a little headroom.

So it seems pointless in going this route then I guess, if I want the lossless through HDMI I can get a modern receiver with the same power as my Marantz for cheaper. Or maybe I can do something externally for bass management, because there is a big difference in bass signals when I switch from analog to my fiber optic...even though I balanced the levels of all 6. It does bother me that the bass lacks when Im getting uncompressed, but maybe the whole uncompressed thing is overrated. In most tracks I hear very little difference, which is why I wondered if maybe Im missing something not supplying more power.

Jake they actually rate it at 105 w per channel x 7 (8 ohms) 20Hz-20kHz at .08% THD. This is deceiving, because in reality each channel at once, going the same time, gets less. Thats why certain companies rate their receivers (Rotel RSX-1550 for example, 70 Watts/all channels driven) with that stat. That RSX could also write 105w x 5 20hz-20khz at .08% THD. It's different ways of wording it per FCC guidelines, now I remember reading it somewhere, I thought by Alan Loft actually, but I can't seem to find it now. It had ways of figuring out the all channel driven power and vica versa. If I can find it I will post it, its interesting.

Erik, you're not going to be "giving my Axioms much more power" unless you turn the volume up higher, possibly endangering your hearing. The all-channels driven spec is meaningless in real-world use at home, as distinguished from laboratory stress tests. You can be confident that your 7400 is capable of at least 105 watts of output(probably a bit more, since receiver power ratings are typically slightly conservative)if on a rare occasion a brief peak in one or two channels actually called for it. Doubling the maximum power output capability to 210 watts would simply mean that the speakers could play a brief peak 3dB more loudly(e.g., 108dB vs 105dB)and would be meaningless unless you actually turned it up that loud. Unused headroom is simply that: unused. So, you won't hear "the" difference because it's unlikely that there'll be "a" difference.

Getting a new receiver for more up-to-date features(e.g., Audyssey MultEQ room equalization)can be a different matter, but don't waste the money that you saved on the sub purchase by chasing an essentially meaningless power spec.

the only "real" benefit to having off board power amps, is that you can just buy a new processor when new technology comes out. the off board power amps will also often have a MUCH more substantial power supply than a receiver will. if i had to guess i would guess that each of my amps weighs about 20-50lbs. somewhere in there, and 80% of that weight is the power transformer...

Hmmm. There's that power supply issue I keep hearing about again. That's what got me thinking that maybe the biggest difference is in the quality of the power supply and not in how many watts the receiver is rated at.

As Dakkon mentions, buying a good, reputable power supply now means never having to replace it so long as you take good care of it (usually). Therefore if you're going to go this route, I would personally get the 200 wpc minimum so that later on you don't get the itch to upgrade it. Then once the technology changes you can upgrade your processor, without having to rebuy the power amps that come in standard recievers. Imo power amps don't gét upgraded in standard recievers, so why pay to repurchase those same power supplies everytime you need to upgrade your reciever?

At lower levels you won't find much difference in SQ, that comes (as you suspected) when the volume knob goes up. Don't get the wrong impression when Quack says 'only 3 dbs'... 3 db's is a HUGE difference! Before I bought the XPA-3, my Denon (volume went from -70 up to +12) hit my maximum comfort volume level at about 0. Once I hooked the Emotiva up, it hit that level at around - 18.

One can hardly distinguish between a 1-2 dB swing at any level, and 3dB is slightly noticeable, that has been fact since audio was a subject. The scale of your volume knob tells you nothing, it is SPL that you need to consider.

Your certainly have taken a 360 on your stance on amplification since the pre-purchase/owning period of the odyssey monoblocks and now after you have sold them. Cognitive dissonance?

IMO I would avoid the UMC-1 pre-pro at all costs. It is riddled with problems and glitches and Emotivas history with pre-pros have been a debacle. A much safer and more stable product would be to buy a receiver with current feature sets from Yamaha, Denon, Onkyo, Harman Kardon, Marantz, Pioneer etc that has pre-outs that you can hook up the external amplifier to.

These “should I buy an amp?” questions come up regularly. Almost daily it seams. I tend to ignore them anymore as the pro/con external amp arguments don’t change and the same folks say the same things over and over again. You might want to search this sight to hear all the rhetoric again. I must be bored to respond…

If you’re set on buying an external amp, don’t go cheap. If you’re going to do it, do it right. Pick yourself up a Rotel, Nad, Parasound, Krell, Bryston, Axiom, McIntosh or other than can compete with those. You will definitely tell a difference, but I seriously doubt it will be a marked improvement is sound quality unless you smoke a lot of dope and tend to believe in fairy dust and the tooth fary. An amp simply..well…amplifies whatever data it receives. This isn’t magic and there’s no voodoo or top secret large breasted virgin hand rubbed electron process occurring in the box. It’s just math. What you will hear differently, will be dynamic peaks. An external amp that has any sand will provide slightly clearer sound at higher volumes and times when there’s a lot going on.

We all know you mean a 180.



And Sirquack if it's your opinion that 3 db's is 'barely noticable' then you're welcome to that opinion. My opinion differs from yours however. I know I listened to my M80's played through my Denon for a good 8 months played at 0 on the volume scale. Then the day I hooked them up to the Emotiva and set the volume level to 0 (instinctually) I damn near blew the windows out of the living room and gave the dog a heart attack. There was no need to pull out an SPL meter to tell me that they were playing RIDICULOUSLY LOUD!!! That was plenty obvious already.

Besides my whole point of telling that story was because previous to that experience I had assumed that the levels would be equal until I got to the very top, and then it would go higher... in other words, I really hadn't thought about it much. But when I almost blasted myself clean out of my seat it dawned on me that when the Denon was running things at 0 it was probably feeding my speakers with around 100 watts. But then once I hooked up the Emotiva, at 0 they were probably getting more like 240 watts.

Which brings me to a point I forgot to mention, above 0 on the Denon things started to get a little shakey... it really sounded as if I was pushing the limits of my M80's (perhaps because I was starting to drive them into 'clipping'). However once I fed them their rated power supply, taking the volume knob ALL the way up gave me nothing but smooth (although insanely loud) performance without that element of fearing for their lives.

In short, trying to crank them without enough power made them sound strained, and I always had the impression they were about to break. Cranking them with their rated power supply showed me that they are not 'delicate' speakers at all. The fact of the matter is they are capable of volumes beyond anything you would ever play them at, and still keep their composure when pushed to those levels. There is a reason they refer to them as 'LOUD speakers'!

No; when something goes full circle its 360°

That's correct. But it seems to me the good Dr. is of the opinion that Sirquack has gone in reverse.

I could be wrong...... I'm not, but I could be.

That pretty much sums up the whole issue in one sentence.

What makes it tricky is that the actual voltage/current limits of the amplifier (and how it behaves at the limit) do not correspond exactly to the power rating, which is why you see reports of "good" 100WPC amps sounding better than "cheap" 100WPC amps.

I'm starting to think we should set up some kind of loaner program where we all chip in a bit of money then buy one piece of "no compromises" equipment and ship it around so everyone can put it in their system and see what kind of improvement it makes before spending any serious coin. Once everyone has a chance to try it out the first piece of expensive kit we could sell it off and start trying out something else.

This is pretty common practice on a number of forums dealing with smaller, lighter stuff (eg $300 flashlights), guess we should check out shipping costs on a 70 pound power amp before going any further

You didn't say anything about sending it back after each individuals' test.

So I call first dibs!

Hmm. That'll be a problem.

To avoid any (ahem) further misunderstanding, each person would be responsible for shipping the equipment to the next person on the list, and lists would be sorted to minimize shipping & customs costs. Mark, that still leaves a potential loophole for the *last* person on the list

I've already secured an attorney to search for loopholes.

Am I being too forward to ask that we select equipment that would look complimentary in my equipment rack?

Thanks for all the input guys, consensus seems it's not justifiable to add an external processor and amp except when you need more headroom, which in reality I don't. What I want really is just a few new aspects of technology (auto cal/Eq, HDMI 1.3 receiver). I always felt this invisible pressure (probably by reviews/magazines as part of the never ending marketing ploy) that my speakers are "missing" their potential without greater, cleaner power. But Axioms are sensitive, pretty easy to drive, so It's hogwash I guess.

Micah, out of curiosity, you use the XPA-3. So how does that work for your backs? The Denon is the preamp for all 5, but only sends power to the 2 QS8s? I've never come across that approach before.

If there are speakers that could use external amplification are Axiom towers. It seems one of the design goals that went into the towers like the M60 and M80 were power handling and the ability to play extremely clean at very high SPL levels and consume large amounts of power to fill large rooms.

Now if you have a large room and your listening/seating position is far away then external amplification can be beneficial. If you run your speakers full range you might find external amplification to be beneficial. The M60 and M80's will dip into the 4 ohm region full range and at VERY HIGH SPL these speakers might shut down some receivers and even some amps (M80s). If you have a small to medium sized room and sit 8-15 feet away for example I see no point in external amplification. The sensitivity of Axioms are above average in the high 80's so this is why receivers usually work for most rooms because they are easy to drive and in most cases not pushing them past their limits.

The one thing Michael_D pointed out is that some of the more expensive amps can handle even 2-4 ohm speakers to unclippable levels with any speakers without shutting down even with the most demanding of source material. The Axiom amp is an example of that. With the emotiva amps on the other hand I would limit them to 4-5 ohm speakers and up. Upgraditis is always happening. With a quality amp, it doesn't lose it feature set like pre-pros and receivers and should last a really long time from a reliability standpoint.

Emotiva use their own proprietary auto equilization/calibration on the UMC-1. While IMO auto equilization is rubbish on quality speakers, I must think emotivas own technology in this regards is far from revolutionary and Audyssey is probably a better feature which is also a trademark on some very popular receivers with pre-outs. If this type of feature is important, you should choose Audyssey over Emotiva EQ. Audyssey is more stable and has a lot more R & D behind it.

Micah, there's a difference between mere personal opinions and matters which testing has shown to be factual. On the effect of a 3dB increase in loudness, both Randy's "slightly noticeable" and the "slightly louder" which Alan has pointed out here and elsewhere are in accord with actual results. Also keep in mind that the power increase required for this slight increase in loudness is logarithmic, not linear, which means that the difference in loudness from 1 to 2 watts is identical to the difference between 100 and 200 watts.

If you want to confirm the small effect of a 3dB increase for yourself, simply play some constant level source(such as the receiver test tones)and then increase the volume control setting 3 points(not precisely 3.0dB, but close enough).

It would be interesting to hear Ian's reasons for the design he chose. There are other advantages to using multiple drivers. You greatly reduce the excursion of each individual driver ensuring that they do not go beyond their design capabilities. That is a good way to reduce/eliminate distortion of various types.

Erik, if you're interested in a receiver with more up-to-date features, such as those you've mentioned, an outstanding buy at this time is the Onkyo HT-RC180 factory refurb available from Accessories4less for about $470 with shipping. When bought from a reputable source, factory refurbs are if anything even more likely than a brand new unit to operate well.

Well I ordered a receiver...the Marantz SR8002 from Amazon with free 2 day shipping only 999.99. Im gonna stick with Marantz, and for this price I decieded to make my move and be done with it as far as the upgrade itch goes. I'll let you know how I like it. Thanks John, Ive had my eye on that site for a while looking for refurbs of the 7002 or 8002. But here a new one is actually cheaper with free shipping.

Erik, just to make sure that you're aware that the 8002 came out about 3 years ago and that there are some units for the same or less cost(including the RC180)that are even more up-to-date in their features.

dreamtheater, those are the guys that i bought my marantz mm9000 from... 5ish years later still working like a champ!.....

A1400-8 anyone interested?

Yeah it is older I realize John, but still it has the HDMI 1.3 which is the main thing I'm looking for in new receiver, and I heard nothing but good things about it, plus I feel some loyalty to Marantz, they haven't done wrong to me yet. I can care less about fancier GUI's and the PLIIz gimmick. Aesthetically I love the look also, much better than the rounded new approach the SR 6004 and 5004 have. I should be all set for many years to come hopefully, and I have no more excuses for getting new equipment now

I had the 8001. It was by far, the biggest damn POS receiver I have ever owned. Not only that, but Marantz was miserable to work with to resolve warranty issues. The 8002 may be better, as it is a second generation of the “new” Marantz receivers, but I’m going to bet you have issues with it within six months of use. If it is not too late, my suggestion is for you to cancel your order and buy something else. I normally do not make these types of disparaging remarks, but would feel remiss if I did not take the time to warn you.

Erik, I didn't go into detail, but I don't believe in staying with a particular brand if a different one has a better performance/price ratio. To mention two features that would be significant to me, the 8002 lacks the networking feature included in the RC180 and it has a dated version of Audyssey MultEQ which doesn't have the significant recent improvements, particularly DynamicEQ and Dynamic Volume.

To me the lack of the latest Audyssey options would be a determining factor.

Eric,

For what it's worth, you purchased one hell of a receiver with a power amp that performs extremely well with a ton of features, 3 years old or not & for a heck of good price. MCACC & Audyssey both have their strengths and weaknesses and quite frankly, IMHO are not the holy grail of purchase decisions.

I'm sure you will love the marantz sound for years to come. Don't look back on your decision and as JohnK says...enjoy the music, not the equipment.

Dana