AMP for these speakers....

[praetorian]

Right guys, a quick one for you.

Am looking to get this pair of speakers from good ole Richer Sounds ... from what I am reading they are fantastic for the price that you pay £69.99



But I am unsure as what AMP to get with this

All I know is the following:

Sensitivity (db) - 89
Impedance (ohms) - 4-8
Bi-wireable
Power Rating (watts) - 90

Now from what I understand, I'm gunna need an AMP that will push out at least 90w per channel to get a decent sound out of them, otherwise I'm gunna get a square signal which is not something that I really wanna get..

Can somebody suggest an AMP to use with these? The only requirements are that it must be in black. Yeah the speakers are in beech but they are going on the walls which makes the rest of the funiture and the black amp will go on the desk with the rest of the black equipment (ie. Lamp, PC, TFT etc). Max price is probably going to be around £200 which should get me a decent AMP for these things. Also it has to take at least 2 inputs cause I'm gunna wire my PC as well as my TV/DVD system into this

Cheers in advance people.

[Zathras]

You don't need a 90wpc amp at all! Who've you been talking to? Look at the Rotel amps at about £200, they often get highly rated.

[praetorian]

A friend of mine who does professional sound systems for nightclubs etc.
He deals with things such as Function One, Prologic etc etc systems and so he should know what he is talking about

So if I don't need 90wpc then what do I need? Considering anything less will not use the speakers to their full potential and anything higher will run the risk of blowing any of the components of the speakers if I jab the volume knob too much

[Flibb]

If you looking at running your PC and DvD, why not go 5.1? Most 5.1 amps have 2 or 3 digital inputs, which would take care of your Dvd and PC (if your sound card has digital out).
Flibb

[praetorian]

Well the PC is soundstorm so it should have digital output but it comes as part of an addon (FrontX) for a 5 1/4" drive bay and owning a Black widow I don't want to spoil up the black of the system. So its gunna have to be analogue out from the soundstorm and digital output from the DVD

[Zathras]

Hmm, yes, that's right - not. A £2000 valve amp rated at less than 20w cannot be used with similar speakers because they can handle upto 200w?

You've got it the wrong way round mate. You shouldn't chuck more power through a set of speakers than the speakers can handle. It's here when square waves and clipping can occur and damage your speakers.

[praetorian]

Ahh okay fair enough .. I always knew that I never fully picked it up

So basically I'm after an AMP that can say handle half or 3/4 of the power that the speakers are rated to yeah?

Also Zathras, could you give me some model numbers and/or places where you can buy Rotel AMPs from please?

[Flibb]

Zathras is right about the power. My speakers are 150w and the amp is 80w, eardrums get painfull at 5/10 power. Volume is normally set to about 1.5/10, or I crank it up to around 2 if my wife and neighbours are out.
Flibb

[Flibb]

Whats your priority dvd or music? If its dvd you need a 5.1 amp and speaker package, this means having a 5.1 decoder/amp, 5 normall speakers and a subwoofer. This will give you great dvd sound but not so hot music from cd. If its music you are after you will need a cd player/tape/md deck/record player ( (most dvd players are arse at music), stereo amp and 2 speakers. Also you wont be able to plug you dvd player into a stereo amp digitally, as the amp wont have a decoder or any digital inputs. Its difficult to get everthing from one system, so like me you will need to decide if you want dvd or music as your priority.
Flibb

[5lab]

you only need a cheapish amp - marantz do a nice 30wpc job for about £130

[Howard]

Your mate knows nothing.

Sod the power ratings, just get a GOOD QUALITY amp. Better quality amps have FAR less chance of damaging speakers at any power rating than cheaper ones that claim to be really powerful.

Look at some of the ones from Marantz and Cambridge Audio from Richersounds. ALL of those will suffice.

[5lab]

a 30w amp + them speakers - you probably wouldnt need the amp more than 1/3 up to drive them plenty loud enough

[Howard]

All depends on the impedance (Ohms). The lower the impedance, the more sensitive they are, i.e. easier to drive. If they're something ridiculous like 16 Ohms, they'll be hard to drive to louder volumes.

[Rave]

Originally posted by Howard
All depends on the impedance (Ohms). The lower the impedance, the more sensitive they are, i.e. easier to drive. If they're something ridiculous like 16 Ohms, they'll be hard to drive to louder volumes.

No, sensitivity is the volume of sound they produce for a given input wattage. These speakers claim to be 89dB/W, which I seriously doubt, they're probably about 83-84 in reality. Still plenty loud though. My friend had some speakers which genuinely were 89dB/W and they could go as loud as you liked with pretty much ANY amp. It helped that they were 4ft tall, made out of 1" thick MDF, weighed 5 stone and had an 8" Audax carbon fibre woofer. Anyway, lets think about that for a minute. If you're putting 1 watt through these speakers they're going to be producing 83 or so decibels, which is not exactly quiet. it'll only take 30 watts or so to get them to around the 100dB mark.

Now, there are two ways to blow up speakers. You can overpower them with a really powerful amp and blow them up by overheating the coils (or occasionally by damaging the cone- this is less likely) or you can use too weedy an amp. If your amp can't supply enough voltage to hit the peaks at the volume you've selected, it 'clips' the signal. This creates a lot of high frequency signals, which is why the music sounds very harsh, and these high frequency signals can fairly quickly overheat the tweeter and blow the coil. This is more likely to occur with high impedance speakers, as they require a higher voltage to flow a given amount of power through the speaker, a voltage the amp may not be able to provide.

If you use low impedance speakers, the amp is more likely to struggle to supply enough current. This also sounds crap, but it's not as bad as clipping, it just (in my limited experience) makes the music sound very flat and wooly. You might be able to overheat the amp this way but it's unlikely to hurt the speakers. However, if you're using low impedance speakers then you really do need an amp with serious welly unless they're very sensitive. B+W's professional monitor speakers used to have a sensitivity of about 83dB coupled with an impedance that went as low as 2Ohm in part of the frequency range You really need something like a Krell amp to whip 'em into shape. Still, you're probably not going to couple a pair of £8000 speakers with a cheapo amp from Richer.

So, back to your question. Any decent 30+w amp will be fine for those speakers. I spotted in Richer's ad in What Hi-Fi that they have the Cambridge Audio A1 Mk3 for £69.99 at the mo (possibly only if you quote the ad). That would be fine. If you want a bit more welly (which these speakers probably won't be able to use, but future upgrades might) then I hear the A5 is good at £120.

BTW, I can't tell from the picture if those are the JPW ML310 or 510. If they're the 310 then the What Hi-Fi ad says they're £39.99, or at least it did last time I checked. Never go to Richer without popping into Smiths to read What Hi-Fi first.

Rich :¬)

[Butuz]

Originally posted by Howard
All depends on the impedance (Ohms). The lower the impedance, the more sensitive they are, i.e. easier to drive. If they're something ridiculous like 16 Ohms, they'll be hard to drive to louder volumes.

Hes right! Impedance basically is the internal reistance of the speakers coil, so the lower the internal resistance the easier they are for the amp to drive. So 16ohm speakers are harder to drive at any given amp wattage than 8 ohm ones wich in turn are harder to drive than 4 ohm speakers. Ever wondered why all the bad boy subwoofers in the back of max power all had crazy watages? Coz theyre all 4 ohm speakers, easy to drive, so the manufacturers rate them as higher watt speakers than 8ohm ones would be.

And also the Sensitivity (db) plays a big part in this too as the lower the sensitivity, the harder the speakers are to drive which means that speakers with a Sensitivity (db) of under 90 make the amp work harder for any given volume than speakers that are 90 or over.

EG the speakers in my guitar amp have a Sensitivity (db) of 100, very easy to drive, you only need to put 5 watts of valve goodness down em and they go loud as the proverbial even tho the amp is 5 watts and the speaker is 60 watts. Watts are a poor measurment because theres not really a set way of exactly measing them that all manufacturers stick to.

Anyway as a rule of thum your amp should not need to be more than half the watts of your speakers. If it is more than half, then you risk damaging your speakers if you rally bump the amp up.

praetorian sorry to say your mate sounds like one of the "i am a profesional i know it all" types that actually dont understand any of the theory behind what they do - you know kinda like the PC world store assistants that think they can talk you into or out of anything but dont really know what theyre talking about?

Butuz

[praetorian]

Cheers for all your replies peeps ... you've certainly enlightened me further into the world of home sound systems. Car and nightclub sound systems I'm fairly okay on but home is completely a different story Oh well canna be good at everything

I'm probably going to go for the cambridge audio A1 mk3 or A5 cause they are definately brilliant makes for the prices.

@Butuz: The guy that gave me this advice was right but I had it the wrong way round so it was totally my fault to start off He runs his own professional sound and lighting rig company and has been for the past 5 years doing massive events for some high profile customers. It was most definately me that had the correct intention but had the information completely and utterly the wrong way round /me slaps self silly

Once again thanks for all your help/information/advice on this one. Next time I will be more careful with the words that I use