# New...still trying to figure this stuff out



## canyonfootball07 (Nov 29, 2008)

I keep looking at different HT receivers and they have separate rms ratings for 20hz to 1khz and then a higher rating for 1khz-20khz. Subwoofers would fall into the first range. I am assuming then that at those frequencies the amplifier would put out less power? and then therefore something like the ep2500 would only put out 1300w to my subwoofers? help appreciated


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## Wayne A. Pflughaupt (Apr 13, 2006)

> I keep looking at different HT receivers and they have separate rms ratings for 20hz to 1khz and then a higher rating for 1khz-20khz.


Can't say I've ever seen this method for power rating. Can you give us a link to an example?

Regards,
Wayne


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## tonyvdb (Sep 5, 2007)

Those ratings do seem odd. Typically the ratings will be 20-20,000Hz but these numbers are just based on averages and mean very little. Other important numbers are Total Harmonic distortion (THD) and Watts (RMS). There are many cheep manufacturers that will fudge these numbers and make them look better then they really are for example a Home theatre in a box system that has a rating of 1500watts??? That is totally false and un-realistic given the size of the speakers and amplification section.
The bottom line here is you get what you pay for and try to stay away from the no name brands and the deals tyhat seem to good to be true.


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## canyonfootball07 (Nov 29, 2008)

sorry. I wasnt looking at the page when i posted this but yes the first is the 20hz-20,000hz. here is the link to the behringer manual which i was looking at
http://www.behringer.com/EP2500/index.cfm?lang=eng
and then if you click on the link to the right of the page that says manual and there is a chart rating the output. There are two very different outputs for the lower frequency range and then a higher output for the higher frequency range


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## Wayne A. Pflughaupt (Apr 13, 2006)

> There are two very different outputs for the lower frequency range and then a higher output for the higher frequency range


Hmm... Can't find that. All I see is a rating for 20 Hz- 20 kHz @ 0.1% THD, and a rating at 1 kHz @ 0.1% THD; pretty standard stuff...

Regards,
Wayne


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## canyonfootball07 (Nov 29, 2008)

thats kinda what i was asking. sorry if i phrased it wrong. Is that the output at those frequencies?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Basically, there are two recognized standards for rating power amplifiers: FTC and EIA. 

The FTC standard, established back in the '60s or '70s by the Federal Trade Commission, requires that a manufacturer’s power specification must be met with both channels driven over the advertised frequency range at the advertised total harmonic distortion (THD) rating. Typically manufactures use the full bandwidth audio spectrum - 20 Hz to 20 kHz - for this rating.

The EIA rating, established by The Electronic Industries Association, is the power output for a _single channel_ driven at mid-band – typically 1 kHz – with 1% THD. This standard tends to inflate the amplifier’s power rating up to 10 to 20% higher than the FTC rating, because it takes more power to drive a full bandwidth signal than a single frequency signal.

One method isn't necessarily better than the other, as long as you're comparing "apples to apples" from one amp to the next. Most audio enthusiasts feel the FTC method is more of a "real world" method since most audio program material is wide-bandwidth, carrying everything from high frequencies to low.

Notice too that that with FTC ratings, many manufacturers can show that their amplifier's full-range power spec is accomplished with THD specs that are significantly lower than the EIA's 1% figure - 0.01%, 0.001%, etc. An amp with a EIA power rating @ 1% THD might be putting out significantly less power at a lower distortion level. 

Hope this helps.

Regards,
Wayne


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## canyonfootball07 (Nov 29, 2008)

oh ok. thank you. that was what I was trying to figure out. Very helpful, I was just confused and wanted to know the realistic power for an amp. I will just base what i get off the FTC rating.


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## ampire (Nov 27, 2008)

canyonfootball07 said:


> I keep looking at different HT receivers and they have separate rms ratings for 20hz to 1khz and then a higher rating for 1khz-20khz. Subwoofers would fall into the first range. I am assuming then that at those frequencies the amplifier would put out less power? and then therefore something like the ep2500 would only put out 1300w to my subwoofers? help appreciated


This is slightly unrelated, but if you go with the EP2500, it has a "low cut filter". This filter is really a high pass filter, meaning that it "blocks" frequencies below 30hz or 50hz, selectable with dipswitches.

You would want to disable this filter. This is very simple and easy to do, just adjust the dipswitch in the back. The crossover does not strictly block any frequency, rather it decreases the volume significantly below 30hz or 50hz. Therefore, since you expressed concern that the EP2500 would put out 1300 watts to your sub, I figured this might be informative. The purpose of this filter is to protect tweeters and sensitive midrange woofers on your fullrange speakers. I use a EP1500 for my mains and I use the 50hz, its a great feature for this but not something you want enabled for your sub.


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## canyonfootball07 (Nov 29, 2008)

cool thanks. Im still trying to gather info and decide what I wanna do and what I wanna get so I dont waste money on something that is insufficient


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## tonyvdb (Sep 5, 2007)

1300watts seem like plenty of power as a matter of fact its most likely overkill (this is a good thing) as distortion will be far less likely. What sub(s) are you planing to drive with it?


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## canyonfootball07 (Nov 29, 2008)

havn't quite decided yet. I havnt even fully decided on the amp. Im kinda playing it by year I have 2 15" btls im either gonna put both in my truck or one. If I put both in my truck then i have 2 10" fi Qs and those will probably get hooked to the amp. I am just waiting to see how the cookie crumbles and what I have to work with.


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## ampire (Nov 27, 2008)

canyonfootball07 said:


> havn't quite decided yet. I havnt even fully decided on the amp. Im kinda playing it by year I have 2 15" btls im either gonna put both in my truck or one. If I put both in my truck then i have 2 10" fi Qs and those will probably get hooked to the amp. I am just waiting to see how the cookie crumbles and what I have to work with.


Assuming your enclosure is big enough, 1300 should be fine for good volume

I got my ep1500 used for a bit over 100 from some DJ on craigslist so you could always hunt around for used pro stuff. Another good amp to look for are the Crown Macrotechs


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## canyonfootball07 (Nov 29, 2008)

thanks. Ya basically its going to be when I finally get my car set up finished up im going to look around on ebay and see what my options are. Thanks for the recommendation. Im probably gonna look for something on the cheaper end that puts out about that wattage maybe a bit more


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