Ok, so here's a result. Not very scientific. I have been using a 50W. I listened at good levels with a song that has very big transients. It completely saturated. It was awful. I've got my proper amp connected now, and it's a completely different story! No distortion, and the amp doesn't sweat. So there. Headroom is definitely needed.
Have you done the test?
What it determines is the highest you ever set your Volume Control. You do this on MUSIC that you listen to.
This (with your precise amp) decides how much power you need. Once you've found your max volume setting, the test turns that into a required voltage (& power) spec.
Why don't you do the test and tell us what you find?
This is the thing - my 50 W couldn't reach the level I wanted. I have my proper amp connected now. Put it as loud as I could ever want (it's obscenely loud). I measured 17 V, so I'm not sure how this can happen with -12 dB because the music is perfectly clean, but I can't reach 68 V with that amp. Anyway, I'll measure again before I post. I'll use my scope.
Mooly, you'll be interested to know the amp is properly grounded now. But here is why you can't touch anything electrical anyway.
Mooly, you'll be interested to know the amp is properly grounded now. But here is why you can't touch anything electrical anyway.
Attachments
- Set your volume control to play MUSIC as loud as you ever want.
- Without touching or changing the volume setting, play Pano's test tone on the same source & measure the voltage at the speaker
terminals
Are you saying you measure 17Vrms?
What was the MUSIC track you used to set the volume?
Thanks. The 6.5" or the 8"?
I'd be curious to know that the test signal voltage reads at a "normal" loud level, one you might typically use that isn't insanely loud. Wondering how close you are to clipping with the smaller amplifier.
FWIW, in my cave system, I could use a setting that resulted in EDIT: 25V volts on the test tones. The drivers hated it, but the amp wasn't clipping and the room just soaked it up. Blew a few tweeters that way.
I'd be curious to know that the test signal voltage reads at a "normal" loud level, one you might typically use that isn't insanely loud. Wondering how close you are to clipping with the smaller amplifier.
FWIW, in my cave system, I could use a setting that resulted in EDIT: 25V volts on the test tones. The drivers hated it, but the amp wasn't clipping and the room just soaked it up. Blew a few tweeters that way.
It's the 6.5" - a very nice driver.
It's not exactly normal levels, but I used Metallica because it is metal, and being so, there aren't surprises in the music; massive transients (it happens, but not often in this genre). Now, when I listen to Pendulum at more "reasonable" levels, there are transients which create massive excursion. If I had to put Pendulum on at the same level as what I had Metallica going, I may have had projectiles, not drivers. Point being, that if I'm alone and I really want to wind it up, it is perfectly reasonable that I will achieve these voltage peaks.
I didn't exactly enjoy putting 30 Wrms of test tone onto my speakers, but it's not going to damage anything quickly. Impedance is 6.7 ohms at 120 Hz. The thing I did enjoy was listening to the speakers give me lots of SPL. I've just built them, and I haven't taken them this far yet. I carefully watched the driver excursion to make sure I wasn't near the 10 mm limit.
It's not exactly normal levels, but I used Metallica because it is metal, and being so, there aren't surprises in the music; massive transients (it happens, but not often in this genre). Now, when I listen to Pendulum at more "reasonable" levels, there are transients which create massive excursion. If I had to put Pendulum on at the same level as what I had Metallica going, I may have had projectiles, not drivers. Point being, that if I'm alone and I really want to wind it up, it is perfectly reasonable that I will achieve these voltage peaks.
I didn't exactly enjoy putting 30 Wrms of test tone onto my speakers, but it's not going to damage anything quickly. Impedance is 6.7 ohms at 120 Hz. The thing I did enjoy was listening to the speakers give me lots of SPL. I've just built them, and I haven't taken them this far yet. I carefully watched the driver excursion to make sure I wasn't near the 10 mm limit.
Hmm, What determines highest level..... ?
Well, are we talking peak, safe average, or thermal ....?
For me.........
Peak....drivers striking plate
Safe average....crap falling off shelves, pictures falling off the walls, the usual...
Thermal.....cops
Your brain sending nerve impulses to your arm and fingers and any other body parts necessary for knob twiddling
Yup. It's a KNOB POSITION
If you regularly listen under those conditions, its the Volume Control setting that achieves all the above. Then you play Pano's test signal to find out if you have enough power.
Jokes aside, YOU set the level depending on YOUR MUSIC and the loudness level YOU like.
If you like your music completely saturated. It was awful. it may not be worthwhile getting a bigger amp as recommended by the test as it won't have the completely saturated, awful sound.
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I don't think the power rating of the amplifier or maximum voltage should be seen as just being about the ability to provide output power.
When you design an amplifier with higher rail voltages you likely impact other things too.
You need to use higher voltage rail capacitors. High voltage electrolytic capacitors are made with thicker oxide layers, they tend to be technically better than lower voltage types. Some people have claimed that the 'sound' of high voltage electrolytics is better.
You have a higher voltage to the active circuit elements. Bipolar transistors, which suffer from the Early Effect tend to perform better at higher operating voltages. Their distortion when used as common emitter amplifiers is reduced.
Resistor loaded amplifiers have more headroom to use higher value resistors and achieve higher voltage gain or lower gain with more headroom.
Higher power amplifiers are often designed to a higher standard. A fault condition at high voltage with the potential for high current at a high voltage means very high energy flows. You have to know what you are doing.
Power supplies require larger transformers which tend to have lower impedance.
Multiple paralleled output devices are often required at higher power (> 50W or so for Bipolar output stages) and this results in less current variation per device, and that means lower inherent distortion.
And the list goes on.
What I'm concluding is that a higher power amplifier may actually be a better and more desirable amplifier depending on it's design even if you don't actually need the power for your normal listening levels.
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Anyone wants to build a a high quality 12W/8ohm amp? Get yourself Slone's "The Audiophile's Project Sourcebook" and the schematic of figure 6.10 presents a "Micro Mite" amp that performs marvelously. I have built one with 24Vac center tapped, 2A secondary transformer. This is a proof that the SQ lives within the schematic, and not esoteric parts.
btw: in order to supply the results for the poll, I should get the 120 Hz signal from the beginning of the thread, play some music as loud as I think it's loud enough and then measure the voltage with 120 Hz sine wave? Post the rms voltage here, right?
btw: in order to supply the results for the poll, I should get the 120 Hz signal from the beginning of the thread, play some music as loud as I think it's loud enough and then measure the voltage with 120 Hz sine wave? Post the rms voltage here, right?
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Yes, I think that's partly true. I'm not sure about the sonic advantages of parallel output devices tho. Generally big amps are underused at home, so could be performing like a small amp with a massive PSU.
Certainly, tho, I heard and built low voltage amps that sounded and measured extremely favorably. You don't have to cheap out when building a small amplifier. Most be dozens of examples here on this forum.