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  1. #1
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    matching speaker watt rattings with Musical Fidelity A300

    I want to purchase the musical fidelity a300 integrated amp. From what I understand the power watt ratings of the a300 is 150watts per channel. All the bookshelf speakers I am considering have a recommended ratting of 20watt - 120watts. Will I be able to use a floorstanding speaker like the monitor audio b4 or b6 which is rated at a power handling rms of 150watts or will I need a speaker ratted higher so I will not overdrive it??

  2. #2
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    You don't have to worry about matching amplifier watts with a speaker's "power handling" wattage ratings.

    Different numbers altogether. The power handling of speaker is generally quoted electrically. Truth is, it is highly like the drivers in the speaker will reach their mechanical limits long before the electrical limits. All depends on the speaker. That said, these will be playing pretty darn loud by the time you reach that point.

    You only overdrive the speaker when you crank the volume on the amp. For most listening, I'd bet you are using only 1 or 2 watts.

    If you find a floorstander you like, by all means go ahead and enjoy.

  3. #3
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    so there will be no problem matching the musical fidelity a300 with a pair of B&W DM602 s3 bookshelf speakers?? howcome speaker companies put a power handling ratting on their speakers then?
    Here are the specs btw

    http://www.musicalfidelity.com/mf/en...e.jsp?pid=3397

    http://www.bwspeakers.com/index.cfm/...AC761A45B9AFEE

  4. #4
    RGA
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    It is my opinion that there is no need to put watt rating on a speaker - Mine don't because there is no need to. Some speakers put minimum power 20 watt -- but you can drive a 3watt SET amp with ANY loudspeaker -- the maker posts the min figure because this is the minimum power he things is needed to drive it properly - but there is no REAL reason beyond that.

    The maximum number is the theoretical max the speaker can handle on undistorted non clipping amplifier feed to the speaker. 15 watts of such clipping will fry just about any speaker so the max watt figure is again useless.

    There are AUDIBLE reason you may want a big ass beefy amp and it's probably related to GRIP on the bass where impedence usually dips. Likely why you see subwoofers with 1000 watt amplifiers.

    The watt number on a speaker means IMO that buying anb amp with more watts is a waste of money -- unless the amp is offerring something else you like like better sound. You can use an amp below the speaker's maximum just fine as well.

    I typically don't like high watt amplifiers though I heard some odysseys today driving some Gershman Acoustics X-1/Sub ones that were quite nice -- the tube preamp from Sonic Frontiers was also very fine.

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    Quote Originally Posted by ninetynine
    so there will be no problem matching the musical fidelity a300 with a pair of B&W DM602 s3 bookshelf speakers?? howcome speaker companies put a power handling ratting on their speakers then?
    Here are the specs btw
    No problem at all. In fact, it's rare that speakers and amps match each other. As for why speaker companies put the power handling rating in the literature, well, I'm not sure, probably to give people a guideline as to maximum power, except this if often wrong.

  6. #6
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    Quote Originally Posted by RGA
    It is my opinion that there is no need to put watt rating on a speaker - Mine don't because there is no need to. Some speakers put minimum power 20 watt -- but you can drive a 3watt SET amp with ANY loudspeaker -- the maker posts the min figure because this is the minimum power he things is needed to drive it properly - but there is no REAL reason beyond that.

    The maximum number is the theoretical max the speaker can handle on undistorted non clipping amplifier feed to the speaker. 15 watts of such clipping will fry just about any speaker so the max watt figure is again useless.
    I'm not sure I'd go so far as to say there's no need. Think of the guys who love to crank the hell out of their systems...they probably quote the maximum power handling to protect these guys from themselves.

    The max power handling rating generally refers to the voice coils ability to absorb electrical energy without damage...bigger coils handle more. This figure is quoted RMS so in reality, the musical power rating is much higher (which is part of the reason why you can drive more power to a speaker than its rating).

    The problems begin at the low frequencies though. Excursion demands increase the lower you go, and power handling mechanically drops really fast as you approach the frequency of resonance of the driver. For most 5 or 6" woofers I've seen, this happens rougly in the 30-50Hz region. 8" woofers handle power a bit better, and subwoofers better still.

    The minimum power rating is to protect tweeters from poor amplifiers. Good SET's and SS's won't feed much distortion, but poor ones will. You get a lot of upper harmonics added to the tweeters load, and the power to the tweeter soars from the normal miliwatt range to full watt figures - during peaks you can easily damage the tweeter. This is bad.

    But yeah, the power ratings are kind of broad, general guidelines at best. And there's usually nothing wrong with underpowering a speaker if a clean signal is fed.

  7. #7
    RGA
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    The main problem is there is no safety from oneself -- if the speaker says 100 watts and you have a 50 watt amp you can blow the speaker just as reasy as you can with a 300 watt receiver -- despite the mythos created by some on forums who say you are safer with a high watt amp -- it's not the case. In fact you are safest with the 3 watt SET because driven full on with it's max distortion it simply isn;t "enough" to blow most tweeters -- though I have not personally put that to the test. The point is the Speaker manufacturer will give the excuse that A) you under drove the speaker and you plyed it to distortion and blew it so warranty is void or B) you over drove the speaker and blew it that way. And no doubt if you had an amp perfectly matched then C) you used a bad amplifier which distorted and blew the speaker. Whether a speaker can handle 125 or 175 watts isn't going to be a major deal -- both can be blow with a 20, 50, 125 or 175 or 1,000 watter.

    As for volume level well if you want sheer volume level then high sensitivy and high watt handling and protection circuits are a must because at very very loud levels your ability to detect speaker distortion from the room "add-ins" is much lower and if you can;t hear the distortion then your tweeter is not going to be happy and may blow. "Turn it DOWN"

  8. #8
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    I agree RGA and you allude to some interesting points.

    A speaker manufacturer or a good reconer can tell the cause of failure for a voice coil type driver by the nature of damage when they disect it. There will be different burn marks on the voice coil itself due to different causes, be they clipping at low power, clipping at high power, DC, or just plain old too much power. There may also be other evidence from physical damage to other parts of the driver like shattered parts or bottomed out voice coil formers. I went to reconing school 28 years ago so I don't remember all the specifics, and I refuse to do that stuff myself, but I do remember the gist. Then again sometimes there is no discernable evidence at all except an open coil. Those are usually waranteed.

    Another interesting thing is that you should definately be able to hear a distressed driver if you're over driving it. My cue is for what I call power compression. It's like, I turned it up 3dB, but it only got 1dB louder, and it's starting to sound weird, freq resp is getting non-linear, lack of punch, etc. This is usually from the much talked about heat factor changing the resistance (and reactance) of the speaker.

    I always go for a way overpowered amp to speaker relationship because sometimes I like to really turn it up. The only danger is if I'm not listening well enough, or if I hot patch a feed and make a stupid mistake. Either way it would be my fault. Also where I live in Studio City, the cable goes out for a second way too frequently (f'in Adelphia) and the resulting noise is hugely unbearable. If I have it cranked it may blow something, not to mention send me into cardiac arrest. I'll be back to satellite soon, but I have a few more decisions to make on the HD issues.

    Also I'll mention that I work on large systems for a living, last night I mixed at the Hollywood Bowl. But I also have a home hifi that I try to wring the the most out of my dollar for some acceptable noise. Enjoy.
    Last edited by mixadude; 06-19-2005 at 01:55 PM.

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