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Getting a new power amp


dave1022

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My school bought a Samson servo 600 from CPC Farnell about 6 months ago, but due to a manufacturing fault it has now died. CPC have agreed to exchange the product for us, but since they no longer stock it we have to choose a similar item. The list of power amps CPC sell is here. I was just wondering which of those the great and the good on this forum would recommend we get?

 

It will be used with two passive speakers, and should ideally have two (L+R) 1/4" outputs, and either two (L+R) 1/4" inputs or two (L+R) XLR inputs. It will be used mainly for voice from microphones, and occasionally music from a CD player/computer/MP3 player etc. in a fairly large hall.

 

Regards,

David

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I've just had a read of http://www.prestonelectronics.com/audio/Speakers.htm , which seems to do quite a good job of explaining how to match up a power amp to some speakers. Based on that article, I'm leaning towards getting a Stageline STA 500 which would give 125W/Channel @ 8Ohms.

 

EDIT: Now I've just read http://www.sweetwater.com/shop/live-sound/...uying-guide.php which seems to contradict the first article somewhat by saying that the amp should be twice the W rating of the speakers. I'm now very confuzzled... :mellow:

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I've just had a read of...........

Now I've just read .....which seems to contradict the first article somewhat by saying that the amp should be twice the W rating of the speakers. I'm now very confuzzled... :** laughs out loud **:

Go with the second one, the first is wrong. :mellow:

It's been covered here before many times so I'll not go into it all again, just have a search.

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I'm a fan of the cheaper Crown amps.

Look at the Crown XLS series amps.

XLS 202 would suit nicely assuming price is right.

 

Unfortunately the price isn't right :mellow:. We have around £200 to spend, so would the StageLine STA-750 do the job?

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would the StageLine STA-750 do the job

Almost certainly but the Samson is a better quality item, so this might be a retrograde step!

 

I'd say that most of the brands available at this price will be much of a muchness!

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would the StageLine STA-750 do the job

Almost certainly but the Samson is a better quality item, so this might be a retrograde step!

 

How much of a retrograde step? (considering that the rest of our audio equipment isn't exactly high range)

Would it be a noticeable difference or not?

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I've just had a read of...........

Now I've just read .....which seems to contradict the first article somewhat by saying that the amp should be twice the W rating of the speakers. I'm now very confuzzled... :(

Go with the second one, the first is wrong. <_<

It's been covered here before many times so I'll not go into it all again, just have a search.

 

 

I'm the author of the first article. It's not wrong... it's just not aimed at a school PA system.

 

The article was written from the perspective of live sound and dance club applications where power output is at very high average levels. We OFTEN repair speakers where the user followed the advice of 'amp power greater than speaker power'.

 

For a school auditorium, an amplifier rated at approximately the program power rating of the speakers would probably be adequate. In this case, the user described the application as mostly speech amplification, with an occasional CD, computer or MP3 player. If the amplifier/speaker system is properly designed with enough power to produce the desired SPL throughout the auditorium, it is unlikely that the speakers would be damaged in normal use either by clipping distortion or by excessive power. However, if someone feeds a distorted signal in or drops a microphone......

 

A properly designed amplifier/speaker system will have enough amplifier power that clipping distortion of the amplifier will never occur at any desired volume level, AND speakers that can handle continuous power near the rated output of the amplfier. Using an amplifier with twice the power rating of the speaker (or more) is inviting a trip to the repair shop.

 

I have updated the article to include discussion of damage by distortion, along with a link to an article by JBL discussing various types of program content and recommended speaker power ratings.

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Thanks for the reply <_<

 

The powers that be within my school have now decided to go with a pulse SPA-600 on the basis that it has the same ouput as the samson. I did tell them that getting a cheap unit would result in a shorter lifetime, but as is always the case with economic issues no-one listens. The have also decided to use the spare money for other stuff that we need, which they wouldn't fork out for in the first place, which is a tad annoying but life goes on.

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We OFTEN repair speakers where the user followed the advice of 'amp power greater than speaker power'.

Presumably because they ignored the rest of the advice about using properly set up limiters and and/or running levels in to the amp that are within the capability of the speakers' power handling. If you run an 800W amp flat out in to a 200W speaker, of course it will expire. A little bit of knowledge (advice) is a dangerous thing...

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