Electronics > Projects, Designs, and Technical Stuff
Yet another Audiophile Question.
DW1961:
--- Quote from: ejeffrey on August 05, 2020, 03:50:20 am ---Yes, the thinking is that if you have a 20 watt amplifier driving a 60 watt speaker system and you think it is too quiet you will turn up the volume. But if the amplifier is clipping it won't actually get any louder so you keep turning it up and the clipping will dump a ton of power into the tweeters. This could break them. According to this theory, if you instead have a >= 60 watt amplifier operating at 20 watts and you turn it up one of two things will happen. Either the system will get louder and you will be satisfied and stop turning the volume up, or you will turn it up so much the woofer starts distorting which will tell you to stop before clipping kills the tweeters.
I'm not sure how realistic it is but that is the idea. The idea that low level listening with a low powered amplifier is going to do any damage is just plain wrong.
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From what I have read on other sites and here, you're explanation is exactly correct. If you don't turn up the volume enough to clip, then you're fine. Unless Klipsch has some sort of magic smoke inside their speakers, that rep's response must be totally full of shit. Volts are volts and distortion clipping is what it is.
What I can say is that I cannot turn these Klipsch speakers up past about 50%control knob on my Texas Instruments 3116D Class D amp because the volume in a 16 x 20 foot room is uncomfortable at about 90dBs @ 10'. From the specs, it will put out 22 watts at 19 V at 1% THD.
jh15:
Back in the 70's hifi days 40 watt amps were good at blowing tweeters. Klipsch is saying a low powered amp could blow theirs while clipping. Likely they put a ballpark figure to not blast/play loud them with less than a 60w amp.
And worded not well with some tech support offshore rep.
tooki:
--- Quote from: DW1961 on August 05, 2020, 05:01:05 am ---
What I can say is that I cannot turn these Klipsch speakers up past about 50%control knob on my Texas Instruments 3116D Class D amp because the volume in a 16 x 20 foot room is uncomfortable at about 90dBs @ 10'. From the specs, it will put out 22 watts at 19 V at 1% THD.
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For sure. Those are great chips. I’m working on a project right now using the successor model, the TPA3126. It’s a drop in replacement with much lower power consumption at idle, even at high voltages.
mc172:
--- Quote from: DW1961 on August 05, 2020, 04:18:30 am ---Except that it's rated at 85 watts continuous and 340 peak.
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My comment was heavily sarcastic.
TimFox:
Measuring the actual power level from your amplifier playing music is complicated, since the waveform is far from sinusoidal and real music (not test tones) varies dramatically in level due to rhythm, etc., while you are trying to measure it. The volume control on your amplifier is not a useful guide, and the "audio taper" may not be accurate.
Here is a suggestion if you want to get quantitative:
A normal CD player has a well-defined maximum output voltage, due to the discrete levels in the DAC. I've found that manufacturers sometimes make it difficult to find this value. If you need to measure it, the NAB has a test CD available with specified levels on different tracks:
https://www.nabstore.com/NAB_Broadcast_Audio_Test_CD_Vol_1_p/cp400.htm (price $20, but currently out of stock). My CD player has a full output level of 2 V rms on the normal analog outputs, which is typical.
Now, you need to calibrate your volume control. If you have a stepped-attenuator (or a detented potentiometer), you only need to count clicks, otherwise you need to improvise a dial. Do these tests at a low output level, well below the amplifier maximum, to avoid damage. You need to connect an audio generator (set to a convenient frequency such as 1000 Hz) to the input and a load resistor (4 or 8 ohms, according to taste) to the output and measure the input and output voltages as a function of volume-control setting with a good AC voltmeter (true-rms is nice, but not required, since we are dealing with low-distortion sine waves). As you decrease the volume control (increased attenuation), you will need to increase the generator voltage to keep the output voltage at an easily-measurable level. The mean (not RMS) output power in this steady-state measurement is the V2/R, where V is the RMS voltage across the resistor R.
Now, when you listen to a favorite CD, you have a method to judge the amplifier power that gives you the sound level you want for your music.
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