Magneto_Plasmoid Posted January 30, 2012 Share Posted January 30, 2012 Hey guys, I'm in the market for a power amp and would love your opinions. The two I am currently considering are the Marantz MM7025 and the Emotiva xpa3. I really like the Emotiva but I'm worried they would be too powerful for my current setup as my F-30s are only rated at 150 watts and the XPA 3 is 200 watts, and a friend was saying I could damage my speaker if I put that much power into it. I know a few of you may think a power amp may be a bit excessive for Synergy range, but I am slowly upgrading to RF7 II in the near future and thought I'd start with an amp first! Also no one has been able to tell me specifically what the advantages are and if I will notice a difference with my current speakers. My current setup F-30 fronts C-20 centre S-20 surrounds Sub 12 Marantz Sr7005 receiver Thanks for your help, Quote Link to comment Share on other sites More sharing options...
Beechnut Posted January 30, 2012 Share Posted January 30, 2012 Available power won't hurt your speakers. That's called headroom and is used for peaks (explosions and such) when volumes temporarily spike. For example: If you are listening to your movie and the listening level you like requires 70 watts. If an explosion happens that requires 140 watts and you only have 125 available, your amp will "clip" the signal so as not to hurt itself. The result of the clipping actually can damage yor speaker. Better off to have 200 available for the peaks. A.k.a headroom. Now, that's all things being equal. I can't tell you if those speakers are efficient enough to have enough headroom with the 125 watts or with 200. They may be as a few people here run Marantz ma500's monoblocks. Think they are 125. Quote Link to comment Share on other sites More sharing options...
StephenM Posted January 30, 2012 Share Posted January 30, 2012 a friend was saying I could damage my speaker if I put that much power into it. You can damage a speaker by putting too much power into it; however, just because an amplifier is rated for 5000 watts doesn't mean it's actually going to be pumping 5000 watts into your speakers all the time. The actual power flowing from the amplifier will be dependant upon the control volume, the variance of volume within the source signal, and how efficient your speakers are. Also no one has been able to tell me specifically what the advantages are and if I will notice a difference with my current speakers. The most pertinent differences are the additional power will allow you to turn up the volume a bit more without the amplifier distorting, and the ability to drive more difficult electrical loads. If you don't have reason to believe that you're pushing your current receiver hard, ie you've not noticed any significant audible distortion out of your system, it's unlikely that you will see a great difference simply from moving to an external amplifier. The key questions in discussing this topic are how sensitive are your speakers, how difficult are they to drive, how far do you sit from your speakers, and how loud do you like to listen. Your current (and your future upgrade) speakers are all reasonably sensitive. I do not know with certainly how difficult your current speakers are to drive, although if you've got no major complaints about current performance, then they probably aren't overly difficult. The RF-7II and RC-64II are likely to be fairly difficult to drive. The last two items make a huge difference. If you're sitting 16 feet from your speakers, you will need 4X the power as if you were sitting 8 feet from them. If you listen at reference level (105dB peaks, 85dB average from satellite channels) you need 10X the power than if you listen at -10dB from reference, and 100X the power than if you listen at -20dB from reference. As you might guess from these figures, there isn't a great difference in terms of volume between 100 watts and 200 watts. It's a grand total of 3dB, which is noticable, but not overly significant. Quote Link to comment Share on other sites More sharing options...
StephenM Posted January 30, 2012 Share Posted January 30, 2012 If an explosion happens that requires 140 watts and you only have 125 available, your amp will "clip" the signal so as not to hurt itself. Of course in that case, you could also just turn the volume down by 1dB (a barely perceptible amount) and also not clip. Conversely, if you turn up the volume another 3dB, you'll even clip a 200wpc amp. The result of the clipping actually can damage yor speaker. FWIW: http://billfitzmaurice.info/forum/viewtopic.php?t=1886 Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted January 30, 2012 Share Posted January 30, 2012 More power that you do not use is not a problem. Trying to get not enough power to reach the spl you want can damage the speakers. The amp goes into more of a solid DC pattern in the wave form due to clipping of the signal, DC through the speaker coils cause them to get hot, very hot and they burn out. Go big or go home [] Quote Link to comment Share on other sites More sharing options...
StephenM Posted January 30, 2012 Share Posted January 30, 2012 Trying to get not enough power to reach the spl you want can damage the speakers. The amp goes into more of a solid DC pattern in the wave form due to clipping of the signal, DC through the speaker coils cause them to get hot, very hot and they burn out. I'd recommend reading the above link regarding that topic. DC in Clipping One of the most famous myths regarding clipping is that it produces DC. The assumption is made because of the flat tops and bottoms to a square wave. It's incorrect to think of a squarewave as made up of positive and negative dc components. The only way for a it to be DC would be if there was a non-zero average value over long periods of time. If the polarity changes at all within the time frame that you are looking at, it is simply not DC. What are these flat portions of the signal? It is simply a combination of the fundamental frequency and all of it's higher order harmonics in sine wave form. For example, if you were to play a 20hz tone while clipping, there would be the fundamental frequency (ie. 20hz) and the second (40hz), third (80hz), and 4th (160hz) order harmonics. The sum of these frequencies creates what appears as a squarewave. There are two ways to test this for yourself; one is quite easy, the other is a little more advanced. The first way is simple if you have a variable crossover and an oscilloscope handy. Pass a low frequency square wave. You will notice the square shape on the oscilloscope. Now turn your crossover's low pass filter on. Slowly lower the setting as you approach the fundamental frequency. You will notice the waveform on your oscilloscope slowly rounding off into a typical sinewave. Once you have reached the fundamental frequency, your oscilloscope will show a perfect sinewave. The second way is for your math guys (or for those who like to use Matlab). If you look in the frequency domain using a Fast Fourier Transform, you will see the fundamental frequency and its higher order harmonics only. There will be absolutely no DC present. Quote Link to comment Share on other sites More sharing options...
holtrp Posted January 30, 2012 Share Posted January 30, 2012 Mentioned this the other day, I have never once heard a speaker that didn't greatly benefit from external amplification, regardless of 'sensitivity' and 'efficiency'. Like many others have stated, you won't turn your volume up as high once you get a amp. I used to clip my Denon listening at +0 db volume level with some material. Now I very rarely turn the volume up past -15 db and actually set it up on the receiver so the volume will not go above -0 db for this very reason. I will have to get my SPL meter out since we moved, but at -15 db at my old house, I don't quite remember if it was 'reference level' however it was uncomfortably loud. As for Marantz vs Emo - I have only heard the Emo but dollar for dollar, I would put my Emo amps up against anything on the market. One of the best upgrades out there in my opinion. Quote Link to comment Share on other sites More sharing options...
cornfedksboy Posted January 30, 2012 Share Posted January 30, 2012 I haven't heard the Emo amps, but I do own their DAC which I use as a pre-pro for my Marantz (2-channel set-up). With Klipsch speakers, I will have a hard time moving away from the Marantz sound. The 140 watt Marantz amp will offer more than enough power at $800, but I certainly wouldn't think you made a mistake if you spent the same amount on a 300 watt Emo XPA-2 or got a 3-channel, 200 wpc rig and saved $100.00. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted January 30, 2012 Share Posted January 30, 2012 Like many others have stated, you won't turn your volume up as high once you get a amp. ...or with a properly dialed-in component subwoofer that uses it's own amp. Divide and conquer. The mains and center won't ever see more than 30V in a correctly setup X.1 home theater. The sub takes the brunt of the power, by a factor of 100 or better. I'd advise against letting your wallet, and more importantly your sound quality, become a sucker for headroom you'll never use. If you're contemplating a 200+ watt power amp, measure your current system to be sure you'll actually use it. Analog high-gain amps are fun, until you find out they also amplify every bit of noise that creeps into the system. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted January 30, 2012 Share Posted January 30, 2012 The terms, strain, congested, distortion and dynamic range compression are all term to describe an amp under stress. Most dedicated amp have more powerful transformer in them than avr's. This translate into more current delivered at the output stage in the chain of amplification. Dedicated amps have more realestate for the power supply and to get rid of the heat produced when running you HT. All this would be of marginal interest if it did not have an effect on SQ. Giving speakers all the current that they need to preform properly, will translate into improved SQ wether you listen loudly or softly, stereo or mutichannel, large vs small speakers. Most smaller or less sensitive speaker are harder to drive than larger or more sensitive speakers. In general, most speakers can benefit from power amps. Better current flow means better driver control (dynamic respone) during peaks in movies and music listening. This is where power amps shine compared to avr's. Going with completely separates can get very exspensive, so using the avr as a preamp can have financial benefits. Most of the new avr's have good DAC, formats and other features that make them attractive as a preamp. Notice, I did not talk about watts rating. For example a power amp delivering 2.2 Kva for 5 channels compared to a Denon 5800( one of the best avr's in it's day) delivering 1,1 Kva under no circustance can deliver the same current at it's output stage as the power amp. Therefore, at all times your system if performing better with a dedicated power amp. This is just the way that I understand things. I use amps with my Icon V HT and hear an improvement in SQ compare to just using my Pioneer Elite SC 35 for amplification, The SC 35 is a class D avr rated at 140 watts per channel with all channels driven. Quote Link to comment Share on other sites More sharing options...
superedge88 Posted January 30, 2012 Share Posted January 30, 2012 May I suggest simply going with three of the Dayton apa-150's for the front three. awesome mono blocks, I highly recommend them, and for the price they are very hard to beat. Quote Link to comment Share on other sites More sharing options...
StephenM Posted January 31, 2012 Share Posted January 31, 2012 Giving speakers all the current that they need to preform properly, will translate into improved SQ wether you listen loudly or softly What makes you think current limiting is an issue when listening softly, especially with a reasonably meaty receiver like the SR7005? http://www.hometheater.com/content/marantz-sr7005-av-receiver-ht-labs-measures Into 7 channels, it can deliver 74.6 watts into an 8 ohm load with 0.1% distortion, all channels driven. Thats right about 3 amperes per channel, for a total of 21 amperes. Into 2 channels driven, the SR7005 was able to deliver 200 watts into a 4 ohm load with 0.1% distortion. That corresponds to 7 amperes per channel and a total of 14 amperes. These tests are also continuous, meaning transient peak ability may be higher yet. Suffice it to say, lack of current shouldn't be a significant issue until you're running near reference level, or you're trying to fill an auditorium. Quote Link to comment Share on other sites More sharing options...
Magneto_Plasmoid Posted February 1, 2012 Author Share Posted February 1, 2012 Well I have certainly learnt a lot from all the valuable information you have all posted up, thanks to all for your input. After a lot of consideration and using a power calculator on Crown Audio's website, I've decided to go with the Marantz as it has more than enough power for the environment it will be living in, and I have always used Marantz gear and I love the sound. Also a friend of mine is a Marantz dealer and I got a ripper deal! I've posted my audio woes on here a few times and every time so many people have taken the time to share their wisdom with me and it's very much appreciated. Hopefully one day I can return the favor! Cheers, Quote Link to comment Share on other sites More sharing options...
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