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potterlu
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Amount of extension/travel on a speaker

Hey all,

Quick question for all in the know: I am running a pair of Wharfedale 9.1 speakers powered by (usually) an NAD315BEE (40W/channel), and at the moment, an NAD355BEE (80w/channel) on a trial basis. I am noticing that regardless of which amp I use, I am getting quite a large amount of speaker travel (5 inch cone; I would estimate I'm getting 3/8'' of travel). Is this normal, or am I beating the living daylights out of the speakers and should I stop? I am not sure what to make of the whole situation. Thanks in advance!

Luke

Jan Vigne
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Re: Amount of extension/travel on a speaker

You have not provided sufficient information to allow a simple answer so you'll get the unsimple answer.

It depends.

It depends on whether the woofer is making such large excursions constantly, only when driven hard or only when driven by specific source components such as a turntable. Working from the most likely to the least likely, the turntable is often the source of large woofer excursions due to record warp and/or mismatched cartridge/tonearm combinations. If the woofer constantly "bobbles" when playing discs, you should; 1) make certain the cartridge and tonearm are a good match and 2) look into a subsonic filter for the phono input.

If the woofer makes such long excursions only when being driven hard, then you have to decide how to solve the problem because the problem is you. You'll either have to turn down the system level or you'll put up with the consequences of a mechanical system working at its maximum level of service. First, when the voice coil makes such long excursions it is common for the vc to both slip outside of its gap and you'll hear a clicking noise as the edge of the coil catches on its return trip or you'll hear the vc bang into the back of the driver's motor assembly - or you'll hear both for a very short period of time after which you'll hear nothing. Second, even if you are not driving the vc beyond its limits, you are heating the components and causing reactive changes in the value of those components. The crossovers and the drivers will shift their values and the original crossover points and the designer's intended system load will shift. This means you are abusing the speakers and the amplifier. Granted they are inanimate objects that you own and you can abuse them if you care to but it isn't the wisest thing to do when you consider you are shortening the lifespan of the speakers and quite possibly the amplifier.

If the woofer makes such excursions when no signal is applied or a very low volume signal is applied, then there is a potentially dangerous problem within the amplifier's power supply and you should have this checked before more real damage occurs.

potterlu
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Re: Amount of extension/travel on a speaker

Thank you very much; that answers my question. The answer appears to be me driving a system beyond its limits, and I will have to look into my options for a system that will allow me to play at the volumes I like without damaging equipment. Thanks again.

Jan Vigne
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Re: Amount of extension/travel on a speaker

Buy a speaker with a higher electrical sensitivity and a more benign load.

potterlu
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Re: Amount of extension/travel on a speaker

Hi again,

I actually did some looking around, and came to a similar conclusion in regard to speaker sensitivity before reading your post. However, I'm not sure I fully understand what you mean by a more benign load; if you could elaborate, I'd be greatly appreciative. Thank you for your time.

Luke

Jan Vigne
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Re: Amount of extension/travel on a speaker

Read this; http://www.symphonysound.com/articles/tubefriendly.html

Let me know if it makes sense to you.

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