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Lower Driver Impedamce

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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 13 June 2019 at 11:29am
And at lower driver impedance, maximum voltage will decrease. 

There is actually a design flaw in Tamp TA-series amplifiers. It has built-in limiter but it only works for 8ohm load / ch to prevent clipping.
When using 4ohms, amplifier will clip way before limiter kicks in because limiter itself has no idea about speaker output or rail voltage drop - it is only set to limit the input to a specific value which seems to be very accurate @ 8ohm loads and it works pretty well too! It barely never clips yet giving full power.

At 2ohms / ch.. even worse. Good limiter should take account the actual output too. 




Edited by Tonskulus - 13 June 2019 at 11:31am
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snowflake View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 13 June 2019 at 1:45pm
Originally posted by gen0me gen0me wrote:

Originally posted by Timebomb Timebomb wrote:

I dont understand what you mean by "Dont calculate crest factor of a bassline/peak. Calculate crest factor bassline/sineWink"
You set up soundsystem so rated power is your 0db level. So this is your level to which you compare. Not peak voltage level which is higher. It is a comparrison of power not voltage.

I wrote sine but in fact it is not exact sqrt(2) factor. You see on K10 spec(126V*sqrt(2)~=178V not 200V)
It will be more like undistored peak to rated power factor.
Originally posted by snowflake snowflake wrote:

"The problem is the more distored and less sine looking bass waveform is - the weaker it is percived on same output."

no, quite the opposite.
Make a track with sinusoidal bass on 0db. Distort it add some compression etc. You will have to bring the levels down so overally bass will be percived more silent.


yeah, but when you play it on a system the distortion will mostly not go through the subs but through the kicks/mids. so even if the mastered track has a lower normalised bass level, you can just increase the gain relative to the other track so that the bass amps are still reaching max.

apart from that, the reduction in volume on the mastered track so that the added distortion does not lead to the voltage exceeding the normalisation threshold, is insignificant compared to the perceived increase in loudness from the distortion - this is both becuase of the steep slope of the fletcher-munson curve below 200Hz, and the psycho-acoustic perception of missing fundamental.
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Chris Grimshaw View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris Grimshaw Quote  Post ReplyReply Direct Link To This Post Posted: 14 June 2019 at 9:45am
Originally posted by Timebomb Timebomb wrote:

Originally posted by Chris Grimshaw Chris Grimshaw wrote:

Originally posted by Timebomb Timebomb wrote:

No,  Basslines in real music pretty much always have a higher crest factor than a sinewave, they are pretty much never between a sine and a square wave, always a high crest factor than a sine.

The tune mentioned that was described as having continual sine wave when actually analysed did not,  it has dynamic, like practically all music.

Can you point me to a tune that features these mythical long drawn out sinewaves?  Ive looked, but never found one..


Kaiju - Hunter.

36Hz sine wave, but it's compressed, which adds a bit of harmonic content. IIRC, the crest factor below 100Hz is <2dB.
If you wanna cook drivers, that's my go-to.

Chris

Just analysed it,  with lowpass at 100Hz 24dB then normalised to 0dB its 6.4dB crest factor in the heavy bass section, if i hard limit at -1dB so it is slightly clipping then normalise to 0dB again its 5.39 dB crest factor across the heavy bass section, there are short bursts of around half a second that get down to about 4dB crest factor.

If you just look at the waveform you can see it does not have as high a duty cycle as a sine wave, there is some dynamic to it.  

  


Interesting. I saw someone use WaveLab (IIRC), and it reported about 2dB crest factor. Maybe they only analysed a few cycles of maximum amplitude, though, which would give that result.

Thanks for the sanity check.

Chris
Quality sound from Sheffield
www.grimshawaudio.com
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gen0me View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 14 June 2019 at 7:18pm
Originally posted by snowflake snowflake wrote:

yeah, but when you play it on a system the distortion will mostly not go through the subs but through the kicks/mids. so even if the mastered track has a lower normalised bass level, you can just increase the gain relative to the other track so that the bass amps are still reaching max.
Never tested it on full soundsystem. Always only on 1amp+ fullrange. Im curious. Could be a challenge concerning it will be harder to get the same integrity of sound on crossover 80-150hz than on home audio 600Hz.
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