A question for the enlightened masses here. I found this advert on the Interwebs and took a double take..

Is that all the output power this massive box has? 7W??? Or is that input power??

Seems too low...

Sounds about right

brutus contrary to belief the m90 is only 9.5 w p/c so yes that is about right

id'e say don't let that fool ya Brutus, it's better than claiming to be 200w like some of the cheap empty boxes only to crank the vol and do nothing but laugh

Here is the:

Instruction book pdf

Service Manual pdf

same advertisement of the JVC RC 550

and 2 picture's showing of the " JW " 15 watts max ( Dont have the service manual for the ( JW RC-550 ) just the picture.

 or

7 watt's minimum RMS, at 6 Ohms from 100 Hz to 10 kHz with no more than 10% total Harmonic distortion 

Aha! Thanks gents

traveller...thanks for the PDF's...It clears up many questions I had!!

It's just such a massive box..I was expecting more

7 watts - that's a lot for a portable radio, don't expect more output power from the radio which takes 8 d-cells, and consumes 25 watts.  just for example SHARP GF-9494 has 4 watts per channel, and sounds really loud. 

3-5 watts per channel - usual for portable boomboxes, and those 7 watts for a mono box is outstanding result.

Keep in mind, the manual says that 7 watts is the MINIMUM it produces across a wide sound frequency range. So there's going to be a MAXIMUM somewhere within that range, that is higher than 7 watts.  I'd guess something like 10-15 watts.

traveler posted:

7 watt's minimum RMS, at 6 Ohms from 100 Hz to 10 kHz with no more than 10% total Harmonic distortion 

The key point in the JVC information posted by Traveller is RMS (root mean squared). That implies a proper scientific measurement that can be repeated by any engineer at any company.

Any other figures such as Peak Music Power are quite meaningless. Peak for how long ? It isn't defined so they can put any figure they like.

Something to bear in mind is that an alkaline D cell has a capacity of about 25Whour. So even with ten D cells a boombox drawing 25W will flatten those in 10hours.

Longman posted:

 

traveler posted:

7 watt's minimum RMS, at 6 Ohms from 100 Hz to 10 kHz with no more than 10% total Harmonic distortion 

The key point in the JVC information posted by Traveller is RMS (root mean squared). That implies a proper scientific measurement that can be repeated by any engineer at any company.

Any other figures such as Peak Music Power are quite meaningless. Peak for how long ? It isn't defined so they can put any figure they like.

Something to bear in mind is that an alkaline D cell has a capacity of about 25Whour. So even with ten D cells a boombox drawing 25W will flatten those in 10hours.

And about half that time operating on batteries driving a stereo set of speakers in any stereo boombox at full power and when you are outside this means that you can play your tunes twice as long in the RC-550 than in any stereo boombox with 2 channels driven.  Which makes the JVC RC-550 more desirable to play on batteries outside as you cannot hear the stereo effect outside from any stereo boombox unless you are holding that stereo to hear your tunes unlike the Mono RC 550 that gives the same tunes from any distance

The key point in the JVC information posted by Traveller is RMS (root mean squared). That implies a proper scientific measurement that can be repeated by any engineer at any company. 

That might be true for that specific JVC, but I'm not sure it's true all the time.  Take the Sharp GX-M10 and GX-BT9 for example.  They say 2x17 RMS to the fronts, and 2x33 for the subs, which totals 100W (such a nice round figure, how convenient! ), but then they say its max consumption is only 30W.   How can it put out more than it consumes?

The more I get into this hobby, the more I think most of those numbers are completely fabricated.  Or maybe not fabricated, but calculated using a method totally unique to each company that can't be compared to anyone else's.