# 350 watt speaker, 300 watt amp



## AlexD (Aug 27, 2009)

i am looking to buy a DAP X Series 12" loudspeaker witch requiars 350 watt RMS, haveing no luck finding a 350 watt amp so i had decided that i would use a 400 watt amp for it. The only 400 watt amp i have found that is in stock (not 1 avalible in 57 days...) is £380 witch is aa little to mcuh for my budget, the DAP palladium Series has a 400 watt amp but is out of stock evrywhere in the UK, apart from one site where its 57 days till avalible  just my luck. So my question is would it be alright to run a 350 watt speaker off a 300 watt amp? if so it will save me £100!!! Would the sound quality and output of the speaker be afected by underpowering it?


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## DaveySimps (Aug 27, 2009)

Be sure to do a search for amp ratings and speaker wattage, as this subject has come up several times. In general, you want an amp to be 1.5 to 1.8 times the wattage of your speaker. In your case, I would be looking for an amp around the 600W range. Or 500 watts at the very least.

~Dave


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## AlexD (Aug 27, 2009)

Oh, ok thanks. I posted this mesage and then though to my self y i didnt look for it... sorry


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## museav (Aug 27, 2009)

AlexD said:


> i am looking to buy a DAP X Series 12" loudspeaker witch requiars 350 watt RMS


What about that speaker requires 350W? This has been discussed many times but there is no such thing as underpowering a speaker, it is a matter of providing appropriate power *for the application*. If you wanted to be able to get as loud as possible without really pushing it you might want more like 700-750 Watts, but such 'rule of thumb' numbers do not really factor in the application and are more applicable as a general assumption if theere is no known application. The reality is that if the speaker gets loud enough and has sufficient headroom with 1 Watt feeding it, then a 1 Watt amp would be fine, it is the use and not just the speaker ratings that matter.

With a sensitivity of 97dB/1W/1m you are looking at a bit over 122dB at 1m (on axis) with 350W, whether that is sufficient depends upon factors such as the distance to the listeners, the relation of the listeners relative to the speaker pattern, the desird headroom and the desired output levels. Assuming that all else is equal, the output with 400W would be less than 0.6dB greater compared to 350W and with 300W the output would be less 0.7dB lower compared to 350W, rarely enough of a difference to worry about.


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## Anonymous067 (Aug 28, 2009)

As long as this has been brought up again...

I can't seem to find a sensitivity rating for some of these speakers...
can somebody advise?

d&b audiotechnik - T10


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## jonnyfive1985 (Aug 28, 2009)

Dave and Brad thank you both for your input this is something that comes up alot and you both brought something good to the table. I myself have always tried to go with a 1:1 relationship on amplification.


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## museav (Aug 28, 2009)

I think the most important thing is to understand that speaker power ratings represent the power the speaker is rated to handle and not the amount of power that is required or necessarily appropriate for any particular use. Most of the 'rule of thumb' guidelines come from rental/staging type applications where the goal is to have a system that could be applied to the widest range of applications. Installed systems are a bit different as they typically have a more defined application or range of applications and thus can be approached with more of a focus on the requirements for those particular uses.

There are many other factors involved. For example, you could have a speaker that changes significantly in response before experiencing any catastrophic failure. Some people test speaker power handling based on there being any noticeable (+/-3dB) change in the response, a situation from which the speaker can usually recover. Others test to failure and you have no idea of what that failure was or whether it was temporary or terminal. Some manufacturers use different test signals. There is effort underway to try to resolve some of these issues and develop a 'better' testing standard, but trying to get something that all manufacturers will agree to is difficult. One significant problem is that such testing procedures would likely result in much lower power ratings for many products and make products tested under the new standards potentially look bad when compared to products tested under one of the current standards. The worst part of this is that nothing would legally prevent anyone from reporting data using the old methods, resulting in the common dilemma of what is technically better conflicting with what may be better for sales.

On the d&b speakers, the problem is that d&b approaches many of their products as a system, you use their speakers with their amplifiers that have speaker system specific processing integrated into them. There are a number of potential advantages to this approach but one impact is that the data for some of their products is predicated on that approach. With the T10, instead of a sensitivity they specify the maximum output when used with the d&b D6 and D12 amplifiers. You might be able to back into the sensitivity from that output level, the speaker impedance and the amplifier ratings. Or you could contact d&b directly and see if they have that data, they are usually very helpful.


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## 00AVD (Aug 28, 2009)

There's absolutely nothing wrong with using a 100W amp with a 500W speaker. There's also nothing wrong with using a 500W amp with a 100W speaker as long as you're aware of what it sounds like when the speaker is being stressed to the max.

A lot of speaker failures could simply be avoided if people just used those things on the side of their head... you know... ears!


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## rwhealey (Aug 28, 2009)

Here's an interesting article about speaker failure by Bennett Prescott (PSW regular and cool guy- I demoed an APB board through him)

PDF Warning:
http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf

And a good (but old) article from EV on matching amps with speakers:
PDF Warning:
http://electrovoice.com/download_document.php?doc=2320


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## museav (Aug 31, 2009)

rwhealey said:


> Here's an interesting article about speaker failure by Bennett Prescott (PSW regular and cool guy- I demoed an APB board through him)
> 
> PDF Warning:
> http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf


On the same day a PSW reference, an article including material from Evan Kirkendall and Phillip Graham and a mention of Danley Sound. Reminded me of this, PSW Sound Reinforcement Forums: Product Reviews: Sound Reinforcement => Danley passes the "Evan" test..


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