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Topic: Amplifier Overheating & Shutting Off. - Page: 1

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Hey guys,

Little help needed, I recently bought 2 100W Passive speakers (Power Rating 50RMS/100RMS Each).
I also bought an amplifier to go with them, on the back of the amplifier it says this;

Speaker A + B
MIN REQUIRED LOAD 4Ω = SPEAKER A + B
OUTPUT: 100W/4Ω

On the back of each speaker it says this;

IMPEDANCE: 8Ω
POWER RATING: 50RMS/100RMS


But after about 30 minutes of playing i'd say Volume 7/10 it shuts itself off, i have to let it cool down for 15 minutes of so before it'll work another 30 minutes off less, my question is this, is the amplifier wrong for my speakers?

Btw, i don't connect using any of the 4 Channels, i connect through TAPE IN/OUT with Audio Splitter + Aux Cable into my Midi Controller.

Thanks guys :)
 
Posted Sun 28 Jul 13 @ 9:51 am
The following info is probably written wrong or they are Chinese speakers. Chinese make many mistakes and false statements when printing labels, especially non brand name products. Most probably 50RMS and 100 Watts peak power. There are atleast 8 ways companies mark wattages on labels so be careful. A lot of non brands write wattages that are way out of wack. If they put 1000 watts in a speaker and it lasts 1ms before burning they will mark that the speaker can handle 1000 watts, they just don't make it a point that it's only for 1ms... "EXAMPLE ONLY". The amp markings really mean 50 watts per channel at 4 ohms. Your speakers are 50 watts at 8 ohms. The amp is actually rated at 25 watts per channel at 8 ohms after the math is completed. So your amplifier is actually half the power of the speakers. I am assuming all of this with the info you texted. I would need the actual models of equipment and brand to get exact info...


Also remember the speakers can be damaged by excessive distortion levels even if the amp is lower in wattage


On the back of each speaker it says this;

IMPEDANCE: 8Ω
POWER RATING: 50RMS/100RMS


Speaker A + B
MIN REQUIRED LOAD 4Ω = SPEAKER A + B
OUTPUT: 100W/4Ω



The amp should always be rated higher in power than the speaker ratings so the amp doesn't have to run at high volume levels to push the speaker. Like putting a small motor in a larger car to make it move. Chances are it will overheat. Just for fun try putting a fan on the amp over the grills(holes) to make air movement. That will keep it a bit cooler and it may help from overheating. My rule of thumb is to buy an amp about a third to twice as powerful as the speakers. Just always remember that the speakers are smaller. Not only will you have more power without your amp overheating but you will get a cleaner sound from the speakers as the distortion level will be much less at higher volumes. A 50 watt rms speaker is ussually a home type speaker. Speakers rates at 150 watts RMS and up are in most cases designed to do larger venues. (my references) I'm an electronic technician and sound installer by trade since 35 years. This information in layman terms is from my life experiences.
 
Thanks for your reply, so basically should i buy a bigger amp :/?

There arent any holes either or fans in the amp, just a grill at the back so i'll try buying a small fan and let it blow into the grill constantly and see if that helps,

Thanks!
 
Ya try that... most important is to find a place to blow in air to help keep it cooler. I assume your using it only in your room and not at a gig as its too small. BTW - I added a few lines since you read it for more info.
 
 
It's only a mono amp, so you are in fact running a 4 ohm load with two speakers attached to it. This should be fine in theory, but a lot of budget amps run too hot at 4 ohms, despite their claims to be able to handle it. I've seen this amp before on the repair bench - if you can, get your money back mate. For home use, you could spend that kind of money on a hifi amp from Richer Sounds or somewhere like that which would do a better job.
 
If someone in Maplins told you that's what you needed, they should be sacked!

Did you tell them you were a DJ?

That's an amp designed for musicans, not DJs. And for that money, you're only going to get rubbish anyway (blunt but true).

For home use, you'd have been better off with a pair of powered "home studio" monitor speakers.

this sort of thing
 
Wow thanks for your replies,
I had no idea, see i only ever DJ at friends houses + my house you know the typical "pre drinks music" with USB speakers + subs so this amp + passive speakers etc was completely new to me.
Yes the guy in maplin recommended this amplifier to me :/
I'll have to find the receipt and take it back if not would having fans attatched like the above post help a little?
 
Good luck with Maplins, you'll have a battle on your hands getting your money back, I've been there myself! Stand your ground though, it's not fit for purpose if it won't drive a 4 ohm load without overheating.
 
Yes it looks absolutely like a mono PA mixer/amplifier but it says in the specs 100Wrms power amplifier with integrated 4-channel mixer (2 x 50Wrms). I was probably right on stating it's a Chinese made product with horrible labeling. No such a thing as a mono amp that can have 2 x 50 watt mixer???? There is such a mixer/amp that is stereo and becomes mono when you switch it to use as a mono "front of house" single output and a single mono "monitor" out output but this is not that type of mixer/amp. In my opinion I would say "don't even believe the specsifications". I would return it and tell them you wanted a stereo mixer/amp and try get your money back.
 
^ this.
 
Having had one of those things apart, I'd take the 100W RMS figure with a large pinch of salt as well!
 
Cheers fellas, i'll be sure to return it, just hope the mother hasn't threw the receipt!
can anyone recommend an amp for me?
not too pricey as like i said, its only home use :)
 
If I were you, I'd take the speakers back as well, then start over!

Rather than shop at Craplin, you'd be far better off using a proper DJ retailer.

For example Phase One sell this amp which is much more powerful than the one you bought, it's stereo and it'll be more than adequate even if you upgrade the speakers later.
 
It seems my mum has washed my pants with the receipt in lol, nightmare!

rang maplin and they said i can use a bank statement as proof as purchase but i'll only get instore credit without the actual receipt, so would this be a "better" amp ;/

www.maplin.co.uk/200w-power-amplifier-47371
 
No, that's almost as bad as the one you've got (and it's overpriced).

They want £100 for a 50w per channel amp, but (as I linked to) you can get a 180W per channel amp for a few quid more.

If they won't refund you, use your instore credit for something else, then get a decent amp from a proper DJ store.
 
I'd just like to say in Maplins defence they are very accommodating in returning of faulty/unwanted goods, you don't have a receipt as you have said, but if you can try and give them a near enough purchase date that usually helps them to check their till records, better still if you paid by card.

Their offer of a credit note seems a fair enough deal, you'll not get many outlets offering that.

I've purchased many items over the years from them from computer parts to cctv systems and always have received good service from their Newcastle branch when needing to return any item, no matter what the purchase price.

Most recent was a usb converter that went belly up and was eleven months old, I had no receipt but they still took the time to check their records, couldn't find anything concrete of when I did make a cash purchase but the guy went to the other side of the shop and came back with a replacement converter... thank you very much.

Treat the staff with respect and they'll fall over themselves to help you... basics of life.
 
Its always hard when you are starting out and don't have loads of cash to throw around. If you can't afford to use the cash you have already paid Maplin then the only other amp that they have which would do a far better job for you is this one :-

http://www.maplin.co.uk/power-amp-800-220514

It is more expensive but much closer to what you realy need.

Grovin's suggestion makes a great deal of sense tho. If you can find something else you need from Maplin and can afford to look elseware for a power amp there are better deals to be had.

It would be usefull if you could post a link to show what speakers you are using. Unfortunately if they are of the same brand as the amp they might give you problems when used with a more powerfull amp if you are not very restrained as to how much power you run through them.

Best of luck with it :-D

Daz
 
I have purchased amps from Maplin too.
I got a 200 watt amp and it was not very loud at all.

You need to buy something like a 1500 watt amp to get any decent volume.

Often the rating is peak for short bursts.
This is why I design and build my own so I see what goes into it.
 
nigelwright7557 wrote :
You need to buy something like a 1500 watt amp to get any decent volume.



Not true! It's not the wattage of the amp that matters, it's how efficiently your speakers can turn those watts into sound.

Some of that is down to the drivers and some to the cabinet design & how well the drivers are coupled to the outside world.
 
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