Speaker input vs amplifier

[newtoaudio90]

Hey guys if a speaker is rated 30-130 watts does this mean the amp has to be at least a 30 watt amp?

The reason I ask is I am
Getting a topping TP20 20 watt amp with 13 clean watts at 8 ohms and am considering the Psb image b5 rated 30-130 watts. Thanks

 

[jaudere]

You can use Topping with the said speakers.However only wattage is not important. Sensitivity is important. What is sensitivity of the speakers that you have chosen? For Topping to give good enough loudness, choose speakers that are at least more than 90 db/w sensitive. Higher the better.

 

[newtoaudio90]

Specs list sensitivity as 89db in a listening room and 87 in an anechoic chamber. Which should I be looking at?

Also with impedance the nominal is 8O and the minumin is 4O. Which should i be considering when buying a speaker.

Somespeakers dont list min and nominal just one impedance value, what does this refer to?

Finally with wattage these are rated 20-150 and the 'program' input is 150. What does this mean?

 

[jaudere]

The next questions are
1) what is the distance beteen you and speakers and
2) Do you like your sound very loud?

Nominal impedance is like average impedance. Minimal impedance is the minimum the speaker will show while playing certain frequencies. Looking at specs the load will be unstable for amplifier. Not agood thing but at least with these speakers you know that. For others you may not know how low they are going on impedance.

Secondly, sensitivity is low if you like your sound quite loud and if listening distance is more than 8 feet (approx).

 

[newtoaudio90]

Thanks .

Well I assume all speakers have a 'range' of impedance at different frequencies but only state the nominal impedance?

 

[jaudere]

Have a look at the following link. I have given it as simple example

Iwai Electronics Pvt. Ltd.

There are 2 graphs at bottom. See the right side graph, It shows the change of impedance as the frequency varies. The impedance is highest at Fs (Resonating frequency).

Of course this is graph for single driver shown in the illustartion. The 2 way speaker like Image with the built in passive crossover will have its own graph.

 

[theredcommando]

Recommended wattage IMO, indicates that speaker would perform optimally between that watt range. If amplifier has lower or higher rating, speaker may not perform as the manufacturer intended.

Having said that, most speakers do seem to perform good below recommended wattage. But get that verified first.

Impedance and phase both vary with frequency. Lower impedance and higher phase is difficult to drive for the amplifier. Amplifier might not be able to drive such a speaker(in which case you wont hear anything or amp would get hot) or in worst case amplifier might clip, which is bad for the speaker. This also means that if you happen to play the frequency which for which your speaker has lower impedance for longer duration, it might adversely affect the speaker.
http://www.stereophile.com/content/wharfedale-diamond-101-loudspeaker-measurements

All these are legally correct statements and it doesnt matter to that extent(in many of the cases) practically. In reality, however, it seems that, even if above points are true, easy to drive load(crudly high impedance speakers) and higher sensitivity speakers would most likely work with toppings without many issues with acceptable performance.