Pioneer A-676 - how do I read the spec sheet and get the right speakers?

lincolnshep

Standard Member
Hi,

First off, I admit I don't know what I'm talking about so I need some help from friendly people who do!

I've got a Pioneer A-676 amplifier (I realise this is knocking on but it still works well) but I think I've been using speakers that are underpowered. I have a pair of Celestion 1's and the plate on the back states 8ohms impedance and 10-50w amp range. One speaker is now buzzing and I either need to repair or replace.

I'm confused by the spec sheet for my amp (pdf is attached). This probably sounds daft but it quotes 70w+70w at 8ohms and 95w+95w at 4ohms and I don't know what this means. I wondered if someone who understands the terminology would have a quick look and tell me what power/impedance speakers I need?

Is there any point in getting the Celestion's repaired and carry on using them with this amp or will they just get damaged again?

I know I could ask all this in my local hi-fi shop but I'm always worried about the possibility of being duped into buying something I don't need.

Any advice would be very greatly appreciated and thank you very much for your time (and patience)!

Regards,
Shep
:confused:
 

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BlueWizard

Distinguished Member
The standard for power ratings is RMS (continuous) power to an 8 ohm load with distortion at 0.1% or less. Distortion figures of 0.01 or less are fantastic; the lower the better.

Think of a amp as a device that delivers voltage. For a fixed voltage, if the impedance goes down, then the current goes up, and higher current mean more power is consumed. But, and this is the important part, more voltage is not applied.

Let's use 10 volts as an example. Though this is going to get a bit mathy, you really only need look at the result.

P = V² / R

P = 10² / 8 = 100 / 8 = 12.5 WATTS

10 volts applied to an 8 ohms speaker consumes 12.5 watts.

P = 10² / 4 = 100 / 4 = 25 watts

the same 10 volts applied to a 4 ohms speaker consumes 25 watts.

The 4 ohm speakers is not louder or more powerful because it is still getting the same 10 volt signal, it is simply consuming more current and therefore consuming more power.

The key here is to remember that you don't have more power, you are simply consuming more power. Using 4 ohms or 6 ohms is a way of inflating the apparent power of an amp.

To truly have more power, you have to have more voltage, and that is what you get in a higher powered amp, more available voltage.

Beyond that, pretty much any speakers will work with any amp. If you like the Celestion speakers you have, then it might be worth repairing them. But it would depend on what models they are and what the repair cost.

We would need to know the exact model number of the speaker.

If you want a bargain in speakers, SuperFi.co.uk still has the Wharfedale Diamond 9.1 (5") for a modest £99/pr. Quality speaker and less than half price.

As to power in general, and as mentioned, any amp can work with any speaker. You just have to apply some common sense. Many people have amps that have a higher power rating than their speaker on the logic that they are never really running the amp at full power. And this works, as long as you don't get too carried away.

In your case, 50w speakers and a 70w amp is pretty close. The only thing that could damage your speakers is the guy running the volume control, and if he isn't discrete, then he can blow the speaker with any amp large or small.

Does that help at all?

Steve/bluewizard
 
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