How many boxes have you ever seen, that are capable of playing at 50% or higher volume without distortion? I've never seen one.

So what's the point of having that much power, if you can't even use half of it?

The volume is a 'trim' control nothing more. Think of it as a water faucet knob to control how much water comes out of the nozzle to feed the internal amp.

The amps are set to some maximum value by the design of the radio and amp circuit, the knob controls how much sound flows into the amp. If the input sound level is the right value, it will max out the amp. If the sound is very quiet, then the knob will allow more of an opening to help the input max out the output.

The 'power' is fixed by the limitation of the amplifiers internally and how they are designed. Max is Max, when the input signal reaches a certain height, controlled by the volume knob, the output will reach the maximum level the amps can produce.

So if you have a really loud source, knob will only hit maybe 30% to reach max volume, if you have a soft source, you can move it to 90% to get the output to reach its max.

kitt --thanks for that careful explanation

Couldn't have said it better myself!!!

'NUFF SAID

two boxes i know of can easily play at half volume with no distortion are

jvc rcm 90
jvc pc 55.

My late 80's Magnavox bathroom stereo usually hits 80% with no distortion. On quiet emo or classical source tapes, it can make 100% with no distortion. To put it simply, the extra slider space is there for quiet sources, like crudely recorded and soft cassettes, and my Magnavox could use some because I can't fully crank it on some tapes.

All boombox's actually should start to max out at 50% or more.
That way you know you can get the max power.
Power is limited to how much you can get from 8 D-cell batteries or what ever battery there using.
So you will never see 50 watts RMS on these things.
Unless its P.M.P.O. power

quote:

Originally posted by kittmaster:
The volume is a 'trim' control nothing more. Think of it as a water faucet knob to control how much water comes out of the nozzle to feed the internal amp.

The amps are set to some maximum value by the design of the radio and amp circuit, the knob controls how much sound flows into the amp. If the input sound level is the right value, it will max out the amp. If the sound is very quiet, then the knob will allow more of an opening to help the input max out the output.

The 'power' is fixed by the limitation of the amplifiers internally and how they are designed. Max is Max, when the input signal reaches a certain height, controlled by the volume knob, the output will reach the maximum level the amps can produce.

So if you have a really loud source, knob will only hit maybe 30% to reach max volume, if you have a soft source, you can move it to 90% to get the output to reach its max.

Thanks for the thorough reply. But I would argue that people only use a "soft source" only 1-2% of the time. Such as a self-recorded tape that wasn't recorded at the right input level. The other 98-99% of the time, they're just using the radio or a pre-recorded tape.

You could argue that, but what really would be the point? Also realize that back in those days, these things were engineered on a cocktail napkin and used existing reference designs of part manufactures of the IC's. If you look at the pcb layout of "most" bbx's, you'll find the exact same components and structures in the reference application within the datasheet of the part.

So interstage gain matching was NOT defined by how far the volume knob is turned, only, is there "enough" or more gain needed to get the output to what is called saturation, or the actual limit of the output transistors within the IC.

Also realize that these boards for the most part, where laid out by hand, which made it even harder. A lot of people don't realize what it takes to try to design something, build it, test, market it, and hopefully make a profit from it.

But I still stand by my position that it covers all possible scenerios especially if it has an AUX input.

The only one I have that can play at half volume and more, without distorting, is probably the Panasonic RX-CT900.

I find 'half volume' 'full volume' etc a little irrelevant - any box COULD play at full volume (as in knob setting, not full output) without distortion if the input source level is low enough, (pointless of course as the amp would be quite noisy by that point) the same as a box that distorts at 3/4 volume on a tape recorded with peaks at 0db may distort at half volume if the tape peaks at say, +5 or thereabouts. When using an iPod with my boxes I generally set the box at about two thirds volume and then use the iPod volume control.

Sanyo M-X920L - fire it right up there with zero distortion.

The distortion is from the amps reaching max power already.
It is not that there is more power available.

And whats wrong with a little distortion?

I had the same problem with my 777 until I put stronger woofers to handle the bass and trble and now I crank it all the way to 8.5 out of 10 which is max volume and it really cranks loud with no distortion, I also think that some boomboxes have a nice solid amp with sheapo woofers, And once u change them with better woofers and sounds a lot better.

quote:

Originally posted by Alvinm:
And whats wrong with a little distortion?

It was this same question that "inspired" the introduction of the Ford Pinto. Nuff said...

quote:

Originally posted by transwave5000:
The distortion is from the amps reaching max power already.
It is not that there is more power available.

My dt680 does quite well in this department. When it does distort, it's usually the 330 hz and the mid bass frequencies, not the more powerhungry lower frequencies. Why is that?

On a side note, if a factory 200 watt Bose audio in a car setup to run on 12 volts can manage, I don't see why a boombox can be that far off in both power and bass. If nothing else, why not give the user the option to modulate the power when operating on DC power so that battery life can be controlled as desired?

quote:

Originally posted by Panabox:

My dt680 does quite well in this department. When it does distort, it's usually the 330 hz and the mid bass frequencies, not the more powerhungry lower frequencies. Why is that?

A bit technical, but the deep bass is reaching max, but that causes the higher freaquencys to get chopped up too even if there at a much lower power level.

A car has much more power available than 8 D-cell batteries.

quote:

Originally posted by transwave5000:

quote:

Originally posted by Panabox:

My dt680 does quite well in this department. When it does distort, it's usually the 330 hz and the mid bass frequencies, not the more powerhungry lower frequencies. Why is that?

A bit technical, but the deep bass is reaching max, but that causes the higher freaquencys to get chopped up too even if there at a much lower power level.

A car has much more power available than 8 D-cell batteries.

the 330hz distortes even if the bass is turned all the way down. Try it. Turn the s-xbs and the 100hz all the way down, turn the 330hz to max and the volume to max. What would cause this?
On a side note, how does an equalizer work? does each frequency adjuster have its own dedicated circuitry?

The 330hz boost may be overdriving the preamp section slightly, especially if it's more sensitive in that frequency range.

Often a simple 5 band eq will be controlled by one IC which comprises the tone circuits, with the five centre frequencies independently set using external capacitors and resistors.

I imagine there are different designs in different brands though, some more crude than others.