I'd thought I'd interject here with some information that might be pertinent..
Harmonic distortion is considerably less significant than most people would believe, at least at relativly low levels for everything but 2nd order. (..2nd order levels can be quite high and still be "musical".) Additionally, instead of just providing my exclusive opinion, I've also provided a link below so that anyone can at least formulate an informed base opinion of the subject with respect to their own hearing.
THD:
First note the "T" in THD (i.e. "total"), this context is important, both because of its "summed" nature and because the passbands above and below a given reference freq. are often similar in level (usually "+" or "-" a small percentage - provided of course that the freq.s above and below are "played").
Now then, with respect to reproduced DIRECT SOUND (like singers, insturments, etc. - as opposed to hall sound) THD levels are not terribly important, at least not at the distortion levels we are talking about (less than 5% for 2nd, with decreasing levels for higher order harmonics). To hear (or not hear this effect as the case may be), listen to the levels here:
http://www.pcabx.com/technical/nonlinear/index.htm
(Note that the less "complex" the direct sound, like a single tone as opposed to a complex work of music, the greater the ability to perceive the distortion. Of course though, most music is quite complex.)
There is something of a "paradigm shift" though when it comes to THD and non-direct sound (i.e. "hall sound"). Hall sound is predominatly perceived at the freq. extremes of the recording (i.e. low freq. and high freq.). Moreover this effect is far more noticible at lower freq.s (for a number of reasons). The "shift" then is that the level of harmonic distortion becomes MORE important than the level for the direct sound.
IMD:
One word: BAD. (particularly for reproduced direct sound). With respect to loudspeakers the passband for this to occur is usually narrow and is most often found in the "break-up" region at the top of a driver's passband (where it "rings"). On the one-hand this is "good" in that a crossover can be utilized to filter this. On the other-hand though the level of modulation when referenced to the fundamental is often very high, and sometimes the filter will be inadequete to the task.
Final note: our brain is quite adept at filtering out harmonic distortion, but NOT modulation distortion.
Harmonic distortion is considerably less significant than most people would believe, at least at relativly low levels for everything but 2nd order. (..2nd order levels can be quite high and still be "musical".) Additionally, instead of just providing my exclusive opinion, I've also provided a link below so that anyone can at least formulate an informed base opinion of the subject with respect to their own hearing.
THD:
First note the "T" in THD (i.e. "total"), this context is important, both because of its "summed" nature and because the passbands above and below a given reference freq. are often similar in level (usually "+" or "-" a small percentage - provided of course that the freq.s above and below are "played").
Now then, with respect to reproduced DIRECT SOUND (like singers, insturments, etc. - as opposed to hall sound) THD levels are not terribly important, at least not at the distortion levels we are talking about (less than 5% for 2nd, with decreasing levels for higher order harmonics). To hear (or not hear this effect as the case may be), listen to the levels here:
http://www.pcabx.com/technical/nonlinear/index.htm
(Note that the less "complex" the direct sound, like a single tone as opposed to a complex work of music, the greater the ability to perceive the distortion. Of course though, most music is quite complex.)
There is something of a "paradigm shift" though when it comes to THD and non-direct sound (i.e. "hall sound"). Hall sound is predominatly perceived at the freq. extremes of the recording (i.e. low freq. and high freq.). Moreover this effect is far more noticible at lower freq.s (for a number of reasons). The "shift" then is that the level of harmonic distortion becomes MORE important than the level for the direct sound.
IMD:
One word: BAD. (particularly for reproduced direct sound). With respect to loudspeakers the passband for this to occur is usually narrow and is most often found in the "break-up" region at the top of a driver's passband (where it "rings"). On the one-hand this is "good" in that a crossover can be utilized to filter this. On the other-hand though the level of modulation when referenced to the fundamental is often very high, and sometimes the filter will be inadequete to the task.
Final note: our brain is quite adept at filtering out harmonic distortion, but NOT modulation distortion.
Audiophilenoob said:
Cheers noob
All the best for yours too.
Scott
Excellent discription of THD, I'm somewhat confused by the intermodular distortion though.
The way I thought of IMD was for example when you run a passive speaker hard with poor amplifcation and you hear the tweeter robbed of power thanks to the woofer. You then get that nasty metallic sound.
What this has to do with your description isn't clear. Care to better describe what I'm actually thinking of?
ShinOBIWAN said:
A complex form of distortion occurring when two signals at different frequencies are produced at the same time creating additional signals at various other frequencies and at various amplitudes. New signals are created at frequencies found by adding the original two frequencies, by subtracting the original two frequencies from one another, from harmonics of the original two frequencies (although this particular distortion is classified as harmonic distortion and so is not truly a part of intermodulation distortion), from the harmonics of these two newly created frequencies (the sum and difference of the original two), and from the sums and differences of the harmonics. Needless to say, this form of distortion results in a multitude of additional frequency signals beyond the original two produced, and each of these frequencies may be heard distorting the original signal.
read more about it here
a woofer excurting say 20 mm one way on a bass note while it's trying to play 500 hz would be very bad
ShinOBIWAN said:
In your example of the tweeter robbed of power thanks to the woofer; that is due to current starvation (AKA current distortion, as opposed to clipping which is voltage distortion). As you say, it results in a nasty sound (I call it grainy) and also the soundstage collapses either partly or completely (ie the sound seems to come only from the boxes)
Current starvation is a very common ailment with SS amps, especially inexpensive ones. Current starvation is one of the main reasons that amps sound different. It's not necessary to be driving the amp hard to hear the symptoms. Some amps have trouble sourcing current even at normal listening levels.
The equation V=IR demands that if you don't have enough current into the load, you can't deliver the necessary voltage. Or said another way, the amp runs out of power. The treble is riding on top the lower frequency waveform and if you run out of power and can't deliver the necessary voltage, the treble peaks will be flattened. Isn't that clipping?
Sheldon
Sheldon
ShinOBIWAN said:
The link provided by Audiophilenoob provides a fairly concise general definition. In particular read the first sentence of the conclusion.
Here is another link that relates specifically to loudspeakers:
http://www.audioholics.com/techtips/roomacoustics/HumanHearingDistortion.php
As to what you have described, well it could be almost anything. If it isn't IM distortion from solid-state amplifier "clipping" (which isn't "hard" clipping and is often the result of inadequate current in the amp's power supply - edit ooops, audiobomber beat me to it), then it probably is either thermal compression of the tweeter (leading to increased levels of upper odd-order harmonic distortion which sounds "hard" and "fatiguing"), or mechanical distortion which leads to IM distortion.
If you want to hear the effects of IM distortion just try driving the seas driver you have full range. Then cut-out the drivers natural upper band ressonance with a steep slope. Also checkout the IMD ("modulation distortion") vs. the fundamental ("pure sound") at the same website:
http://www.pcavtech.com/soundcards/techtalk/dist_sound/index.htm
Cheers Al,
I'll have a look-see and fingers crossed he's got the good ones.
If I remember he said they were a Maplins close out special and he picked them up for something daft like £10 a piece. He actually used to post on here regularly but has lost the bug and turned back to commercial stuff But he's got a nice selection of leftovers I've yet to pick through.
I'll have a look-see and fingers crossed he's got the good ones.
If I remember he said they were a Maplins close out special and he picked them up for something daft like £10 a piece. He actually used to post on here regularly but has lost the bug and turned back to commercial stuff
But he's got a nice selection of leftovers I've yet to pick through.
RyanC said:
Sorry Ryan missed this one in all the excitement.
After seeing the benefits of the PC based stuff, I went out and bought an Antelope Isochrone OCX and rigged it up to the RME via wordclock. Its also got the superior superclock in's and out's ready for when I move on from the RME.
TBH the sound I'm getting now is quite amazing, I really couldn't wish for more from a source. However the latency side of things could definitely be improved. It seems to be around 80ms from the amount of lip sync correction I need in Theatertek. Thats with FIR BTW, IIR latency using Waves C4 is negligible but inferior in sound.
I can agree with that. Chasing perfection is fine by me though.
A few shots.
Its taken longer than expected just to churn this single bass cabinet out. I really hope I can move the next one on a little quicker otherwise the weather will be turning soon and I'll lose my window for spraying.
As you can see though they look good, very pleased so far.
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Its taken longer than expected just to churn this single bass cabinet out. I really hope I can move the next one on a little quicker otherwise the weather will be turning soon and I'll lose my window for spraying.
As you can see though they look good, very pleased so far.
pinkmouse said:This thread will tell you all you need to know...
Thanks Al, already seached for through all the AP100Z0 here and that was by far the most informative that I found. Seems to be a good budget mid/bass driver for compact sats though.
I don't know were I'd find the time for more speakers so I think I'll leave them be.
Cheers.
Depends how you look at it but if you take depth as a whole ie. the front most part to the rear most then the depth is 27". Though the deepest part of the cabinet is 20" deep and the height is 26".
These aren't particularly tall cabinets, even with the plinth and sat the total height is only 42". They are quite deep though.
The sat construction is purely cosmetic, the ATC and Scan don't have any rear radiation. So no loading is requred. However just to make sure that the cabinet absolutely dead I'm going to do a heavily stuffed labyrinth to both braced and cancel any possible leakage into the sat.
Not yet but will be later on.
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