Driving high watt speakers w/lower watt amp?

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bwolf

Member
2015-12-01 11:37 am
Hello Friends :)

Newbie speaker x wattage question

I have SONY SS-DX3 speakers. So, they are rated 60-75W Dont know Original Watt rating( cant find)
recently purchased TPA3116d2 50w x2 amp.
Can it handle both speakers at 150W ?
Is it ok to drive high wattage speakers with (slightly) Low wattage amps? how much difference is Ok for efficiency(for both speaker/ amp). im concerned about Sound quality
im noob help me ? thank you very much :)
$_75.JPG
 
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no its a100w amp

2×50W 4-Ω TPA3116D2
2x 30W 8-Ω

I want to connect it to 60-75w 6-Ω speakers (pair)?

It's a 30W amplifier when supplied with 24Vdc and feeding an 8r0 test load. look at Fig 10, THD+N skyrockets past 0.1% at ~31W into 8r0 if you can maintain 25°C and 24Vdc.
It would be rated as a 30W into 8ohms amplifier, if you use a regulated power supply and build it properly.
Maximum supply voltage is 26Vdc, so expect when allowing for mains voltage variations to supply 23 to 24Vdc when quiescent (no output current) and that this would drop to <22Vdc when under maximum load.
That will limit maximum output power to <<30W into 8ohms.
 
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bwolf:

The speakers wattage rating is the MAX you can feed the speaker. There are lots of ways to blow up speakers and feeding them to much wattage is one of them.

If your amp can do 150W you will damage the speakers at full volume. But you won't use full volume because that would be extremely loud. As long as your ears aren't bleeding you will be fine.

It's perfectly acceptable to use a 1 watt amplifier or a 1 million watt amplifier with those speakers as long as you don't exceed 75 watts.

Another way to destroy speakers is with DC voltage. When an amplifier is operating within it's limits it produces AC voltage. If it's pushed too hard it will produce DC voltage which will burn up the voice coils of the speakers. This will occur at high volumes or due to malfunction. Your amp is really a 30 watt amplifier until it begins to distort, the 150W rating is really just a marketing number.

As long as the volume is sane and you arent hearing any distortion you will be using less than 30 watts...which is below your speakers 75W rating.
 
75W* speakers

*Rated. Actually, most likely way less

Of course. I didn't see the speakers when I first looked at the thread. When I did, I chuckled.

Those speakers are from a modern "boom box" or "tabletop hi-fi." Many (probably most) of these devices rely on equalization to compensate for baffle step and bass rolloff. I have actually measured the carcasses of several similar units and they all employed custom equalization with the "tone" setting (digital crap with tone options like "concert hall" ad nauseum) on "optimum" or "flat." So they are only "optimum" or "flat" when you use a unit that's matched to the speakers.

So what does this mean for our original poster? It means that if he uses these speakers with a standard "hi-fi" amp or his Tripath, there may be a prominent baffle step and/or thin bass response. This may or may not be easily remedied by turning the bass control up.

So bwolf, I recommend that you listen to these speakers on a component system, a "real" hi-fi (or mid-fi) system - not a boombox. This will give you a clue as to whether baffle step or deficient bass will be an issue.

I applied the custom equalization concept to some old Bose 301s I have and it really waked them up. I got the idea after measuring these dumpster units. I just did some listening tests with an old Audiosource equalizer I have, then build a simple analog tone filter that goes in the tape monitor. It works really well because it has no controls; it just turns on with the amplifier.
 

johnr66

Member
2009-03-05 1:55 pm
I find these types of speakers to have a really boomy bass characteristic in the upper bass frequencies around 80-100Hz. It is similar to the cheap packaged home theater sound systems or the sound bars. I call it consumer friendly bass because people seem to "ooh" and "aah" at the "wonderful sound". Played next to a set of "hifi" speakers that have a flat response and good bass extension down below 30Hz, the typical consumer will say that the hifi speaker lacks bass punch. :)

If you find the speakers are boomy, you can block off the ports and add stuffing to the cabinet to flatten the sound. Just don't expect to get deep bass given the driver characteristics and the small enclosure volume.
 
Another thing about these "tabletop hi-fis" is that they use underrated transformers. A unit rated "50 + 50 watts RMS" will produce an unclipped 50 watt sine wave with a tone pulse, but the power supply collapses with a steady-state sine wave. Continuous power is typically 12 + 12 watts RMS. In practice this works well, because music is transient by nature. This also allows the use of a smaller heat sink too. The collapsing power supply keeps the device (typically TDAxxxx in these types of units) within its safe operating area. It's cheap all the way, but the clever engineers do succeed in wringing the maximum performance out of a pile of cheap parts.

Of course there's something to be gained in beefing up the power supply, especially with bass heavy music. But then you have to use a bigger heat sink and maybe even bump the voltage down a little. But these integrated units work very well for what they are.
 

Arty

Member
2011-02-24 5:04 pm
q. is it okay to drive high power speakers with a low power amplifier ?
a. yes.
q. is it okay to drive low power speakers with ahigh power amplifier ?
a. yes.

q. are those 2 statements allways true ?
a. no.

q. when are they not true ?
a. impedance mismatch.

q. heck that means?
a. amplifiers have a limit on impedance they can safely drive. if the speakers have less impedance than this value, its not safe to drive them with that amplifier. higher impedance speakers are allso safe to drive. for example, an 8 ohm rated amplifer can drive ANY speaker that has 8 or more ohm of noinal impedance. safely.

and there's your dinner.
 
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