I'm looking for some input on adding an external amp to HT - AVS Forum
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Old 08-15-2013, 05:33 PM - Thread Starter
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I'm wondering if adding an external amp would improve my music on my Polk Audio Monitor 70 speakers, I currently am running them directly off my Yamaha RX--V867 front right and left channels. I believe the speakers are rated for up to 275 watts and my receiver is putting out around 100W. I'm not looking for more volume but better sound (crisper if that makes sense). Any advise would be greatly appreciated.
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Old 08-15-2013, 09:06 PM
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What sound levels are you listening at? You might not even be maxing your avr's amp capabilities now. You might gain more overhead with a better amp but unless you're listening at fairly high levels probably not a lot to gain with an outboard amp. Those are relatively sensitive speakers. Try this calculator http://myhometheater.homestead.com/splcalculator.html. If you do want to add some outboard amps I'd suggest looking at pro amps like the Crown XLS series, good performance for the $ (I have two XLS1500 amps for my l/c/r speakers).

"I realize that somebody playing free music isn't as commercial as a hamburger stand. But is it because you can eat a hamburger and hold it in your hand and you can't do that with music? Is it too free to control?" - Don Van Vliet (aka Captain Beefheart) discussing commercial success in the music biz


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Old 08-17-2013, 10:51 AM - Thread Starter
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thanks for the info, interesting that you mentioned the crown amp because I was looking at the XLS 1000 and wondering if I just got one for my front right and left to help when listening to music in stereo. To answer your question about the level, I'm not looking for more volume, actually the opposite, I was wondering if the higher wattage would improve at lower volumes as if I wasn't supplying the speakers with enough power at lower levels? I contacted Yamaha support and they thought if I did that, they would over power my center and surrounds. Instead he suggested I eliminate my 2nd zone and biamp the front 2 and then if I wanted I could get an external amp for my other zone or zones if I wanted to add more later. I didn't realize you could supply 5 speakers with 2 amps but if adding more wattage only improves volume then that isn't what I'm trying to accomplish anyway.
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Old 08-17-2013, 11:08 AM - Thread Starter
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I would stop at this point if I only used it for movies but want to maximize what my music can sound like.

I forgot to mention what I am currently using if it helps:

Yamaha RX-V867 receiver
2 Polk Audio monitor 70's (L/R)
2 Polk Audio monitor 40's (surrounds)
1 Polk Audio CS2 (center)
2 Klipsch RW10's

I hope I'm on the right track to having a system that I can sit back and get lost in some good music with. It is my first real system other than an older JVC home theater in a box.
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Old 08-17-2013, 01:15 PM
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At lower listening levels your amp doesn't need a lot of power (and it's still a low level of power being utilized by the amp no matter what the amp's capabilities are). Your speakers are nominally rated at 90db and since they're 8 ohm assume that means at 1 w power. Now, 90 db is pretty loud and at 1 watt your avr is not breaking a sweat. If you increase volume to 93 db, you're using approx 2 w now,, to 96 db approx 4 w, to 99 db approx 8 w, to 102 db approx 16w, etc. Now if you want to get loud or use speakers that aren't as efficient....that's something else. Personally it doesn't sound like you have much to gain with adding an amp right now, I'd suggest saving your money for more capable speakers....

"I realize that somebody playing free music isn't as commercial as a hamburger stand. But is it because you can eat a hamburger and hold it in your hand and you can't do that with music? Is it too free to control?" - Don Van Vliet (aka Captain Beefheart) discussing commercial success in the music biz


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Old 08-17-2013, 02:42 PM
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Quote:
thanks for the info, interesting that you mentioned the crown amp because I was looking at the XLS 1000 and wondering if I just got one for my front right and left to help when listening to music in stereo.

You will have almost zero discernible difference after adding any outboard amplifier if you are not pushing your system hard. I have a Crown XLS-1000 for DIY sub duty. I once tried it on my mains also. It's a class-d amp, as you would know, and has an early roll off in the high frequencies.

Also, I could not feel the difference in bass up until the time I cranked it to insane levels. At very high volumes, it really displayed the sonic grunt in lower octaves. But at low volumes, it was as quiet as if I was running my mains off the AVR.

I have Klipsch RF-82 II, which are terribly efficient @ 98dB/watt

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Old 08-17-2013, 06:16 PM
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Hi Bud

I would echo what lovin' and braveheart have said and say that, unless your Yamaha cannot cleanly (ie. no clipping) power your Polks to your desired maximum volume levels, an external amp will make no tangible difference.

With respect to lower level listening, realise that the rated power of an amp or AVR indicates the power it can produce in the given test scenario. In real word use on program material, the power supplied (well voltage actually) at any point in time will be dictated by the size/shape of input signal and the position of the volume knob (ie. desired level). In other words, it doesn't matter what power the amp can potentially produce; if it's not required by the program and volume setting, it's not being generated and sent to the outputs and can make no difference to how the speakers sound. All else being the same, exactly the same amount of power will be supplied to your speakers whether it's from your Yamaha or an external amp.

You may be interested in this thread where we worked out peak power requirements for a fella who was considering adding an Emotiva. You may be surprised at how little power you are actually using. The OP ended up repositioning his speakers and furniture slightly and paying attention to his sub/speaker crossovers and went away very happy. All without spending a cent! Bottom line: the real sonic gains are in upgraded speakers and subs, proper positioning and in paying attention to the room. An amp is the last place to look, and then only if your AVR is struggling to produce your desired maximum volume levels.
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Old 08-17-2013, 06:34 PM
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it doesn't matter what power the amp can potentially produce; if it's not required by the program and volume setting, it's not being generated and sent to the outputs and can make no difference to how the speakers sound. All else being the same, exactly the same amount of power will be supplied to your speakers whether it's from your Yamaha or an external amp.

+1

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Old 08-17-2013, 09:22 PM
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I would expect that your room treatments may have a lot to play with the sound you are hearing. Always start here first.

However, striving for a more “crisp” sound with your current amplifier may have something to do with it's anemic power supply. For example, the Yamaha RX-V867 has a line power consumption of just 400 watts. If we deduct 10 watts for the pre-amplifier stage it leaves about 390 watts for the power amplifier section. Assuming a 45% efficiency for a class A/B amplifier, this leaves about 176 watts actual output power available to drive speakers.

In 2 channel mode this is about 88 watts per. In 5 channel mode it drops to 35 watts per channel. Seems about right given that the amplifier is rated by Yamaha at 95 watts, 2 channels driven, 20->20,000 Hz.

I suspect that what you are hearing when playing music is a distorted signal resulting from an inadequate power supply. Take a look at Yamaha's white paper on the issue. Towards the end of the paper they discuss how over stressing a power supply results in a compression of the amplified signal.

http://download.yamaha.com/api/asset/file?language=en&site=countrysite-master.prod.exp.yamaha.com&asset_id=53052

The thing to bear in mind is that this has nothing to do with “clipping”. It is all about how the amplifier behaves when its power transformer can't provide the necessary current.

So will moving to an external amplifier help your situation. Honestly don't know. But I do know that there is a noticable difference in the sound between my Yamaha HTR-6295 (130 w/c @ 8 Ω) and my Crown SA2 (220 w/c @ 8 Ω). The Crown delivers 600 w/c at 2 Ω with both channels driven continuously. The Crown is also rated at 2400 watts electrical draw on a 20 amp circuit. There is no way my Yamaha comes close to that level of performance.

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Old 08-18-2013, 02:17 AM
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what about if you're looking for more bass? I currently have an onkyo 805 with def tech sm55, sm65 and sm45 and I listen at about -15 below reference on average. The problem I'm currently facing is that no matter how low a crossover I set or even if I set it to full range, I can't seem to get any bass out of the speakers. SVS recommends I set my crossovers at 50 for the center, 60 for the main and 70 for surrounds based on that tool they have on their site, but at these crossovers, I get no bass out of the speakers so I normally set the crossover to 100hz for all and let the subs do the work. Would an amp solve my bass issues?
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Old 08-18-2013, 04:06 AM
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If you have a subwoofer in your system, spending on external amps is a waste of money. Know that your sub is an extension of your speakers and it must pick up from where they roll off. Toss the specs in the bin; the stated -3dB point of speakers are governed by your room acoustics.

It takes far less power from the avr to push a 200Hz frequency than it does for 60Hz signal. For your speakers, I wouldn't cross them at anything below 100Hz and would rather let the sub take over from there.

I'm not saying you cannot use external amplifier on your speakers; but (specifically in your case) bass will be best produced by the SVS you have. Bass frequencies are very power hungry; a dedicated powered sub coupled with large driver is more at home to play those with authority. Bass is only about movement of air and that too lots and lots of it.

5-6" drivers on your sats stacked against a 12" driver for bass duties....I leave the winner for you to decide.

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Old 08-20-2013, 06:20 PM - Thread Starter
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Thanks for the info everyone, sorry for the late response but where I live I have to appreciate the nice weather when it is here. I spent some time Saturday making some adjustments on the receiver and think I made some progress but shut it down to join up with some friends on the water, Sunday I went over your replies and agree that the acoustics of my room are probably not to good, some of the technical info out there sure can make your head spin! please correct me if I am mistaken but it seems like the sensitivity of the speakers can be very important. I realize that an external amp is not the direction I'm going to take at this time and I am thankful for your help because money is definitely an issue here and It seems that wouldn't resolve what I am looking for. I'm thinking I'll have more time to research how to properly set my system up once the cold weather sets in so I hope you are still here and willing to answer some basic questions I have to maximize my system for what I want ( crossover frequencies, how to set the phases using 2 subs, speaker placements and some of the other settings these system's are capable of doing). Again thank you all very much for your time! I'll check back if anyone wants to direct me to some good sites or info that will help me but hopefully for the next couple months I be sticking with my Sony Boom Box (model CFD-G50) outside with the BBQ fired up! If anyone has a remote for that Sony that they don't need anymore I'd love to have it (the lady setting the radio out to the garbage didn't have it) If your mom threw out the radio I feel your pain because I love it and I'm not giving it back.

Cheers!
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