DJ Jules B.

Hi people.

I was wondering how you people get around phase cancellation in the mix. I
have a select few tunes that I just can't get together without the bass
drums cancelling each other out. No matter how I try to position the two
tunes (ie both bang on beat or one *slightly* ahead, they still end up
cancelling each other out - any suggestions?

Thx

DJ Jules B.

--
When you are about to die, a wombat is better than no company at all.

Jik Ronson

Try keeping the slightly out of time.....


"DJ Jules B." <z3101490@student.unsw.edu.auNOSPAM> wrote in message
newsan.2003.07.30.20.49.22.550178.8162@student.u nsw.edu.auNOSPAM...
> Hi people.
>
> I was wondering how you people get around phase cancellation in the mix. I
> have a select few tunes that I just can't get together without the bass
> drums cancelling each other out. No matter how I try to position the two
> tunes (ie both bang on beat or one *slightly* ahead, they still end up
> cancelling each other out - any suggestions?
>
> Thx
>
> DJ Jules B.
>
> --
> When you are about to die, a wombat is better than no company at all.

Somebody

>>I was wondering how you people get around phase cancellation in the mix. I
>>have a select few tunes that I just can't get together without the bass
>>drums cancelling each other out. No matter how I try to position the two
>>tunes (ie both bang on beat or one *slightly* ahead, they still end up
>>cancelling each other out - any suggestions?

Kill the bass on one of the tracks.

Or record one of them to a PC, reverse the phase and burn to CD.

Jik Ronson

Try keeping the slightly out of time.....


"DJ Jules B." <z3101490@student.unsw.edu.auNOSPAM> wrote in message
newsan.2003.07.30.20.49.22.550178.8162@student.u nsw.edu.auNOSPAM...
> Hi people.
>
> I was wondering how you people get around phase cancellation in the mix. I
> have a select few tunes that I just can't get together without the bass
> drums cancelling each other out. No matter how I try to position the two
> tunes (ie both bang on beat or one *slightly* ahead, they still end up
> cancelling each other out - any suggestions?
>
> Thx
>
> DJ Jules B.
>
> --
> When you are about to die, a wombat is better than no company at all.

Somebody

>>I was wondering how you people get around phase cancellation in the mix. I
>>have a select few tunes that I just can't get together without the bass
>>drums cancelling each other out. No matter how I try to position the two
>>tunes (ie both bang on beat or one *slightly* ahead, they still end up
>>cancelling each other out - any suggestions?

Kill the bass on one of the tracks.

Or record one of them to a PC, reverse the phase and burn to CD.

Jackson West

>> I have a select few tunes that I just can't get together without
the bass drums cancelling each other out.

> Kill the bass on one of the tracks.
>
> Or record one of them to a PC, reverse the phase and burn to CD.

I agree with the above solution entirely. Do you understand the
principle behind phase cancellation? Remember high school trig or
calculus? If you'll sit down and read a minute I'll explain what's
going on and you can make your own decision as how best to rectify the
situation.

When you take two waveforms, or sine waves, and add (mix) them, there
is a very basic mathematical principle at work. What do you get when
you add -1 to 1? 0. What do you get when you add -.5 to .5? 0. How
about adding 2 and 2? Well, here we get a bigger number than either,
4. Over time the waveform fluctuates from between 0, full positive,
0, and then full negative. The distance it travels from full positive
to full negative is called the amplitude. The number of times it
crosses 0 in a given period of time is called the frequency.

Sound familiar? It should. It's basic wave theory, and all audible
sound is composed of the oscillation (or waves) of air pressure. On
the atomic level! Who knew DJs could be physicists!?

Now remember your wave from high school. A wave is a squiggly, but
regular, line that rises and falls vertically while travelling over a
horizontal path. The density of matter (air pressure) is represented
vertically. The horizontal axis represents time. You can measure the
median air pressure in a space very easily. But it's the minute
fluctations which create sound. Sound Pressure Level, or SPL, is
measured in decibels, for instance. This represents amplitude. A
tuning device, on the other hand, measures the frequency that the
amplitude changes - in other words, pitch.

Newton was the first to codify calculus, and to a certain extent you
could consider him the first to consider sound in the realm of
physics. Honestly. Before then it was entirely taken for granted.
Well when calculus was invented we now had a clear mathematical system
for adding, subtracting, multiplying and dividing waves (and other
continuous, curved forms). Because what can we really know about a
wave? Only how high it peaks (amplitude) and how often it peaks
(frequency). But in between it could be any number of values. It's a
curve, fer chrissake. Although if it wasn't for geometry or
trigonometry, calculus couldn't exist, it was calculus that created
the first mathematical tools for dealing with real-time fluctation in
values (change over time, delta y over delta x).

I hope I haven't lost you. To me, this shit is gold. It's probably
why I'm not a famous and succesful DJ, but hey, we all have something
to contribute. If you haven't fallen asleep, let me continue...

So what happens when you add two waves? Well, it all depends on the
frequency and the amplitude of the respective waves. In your case,
their basically the same - the TD808 bass drum wave added in equal
parts to another TD808 wave will possess one of two qualities - phase
amplification or phase cancellation.

Phase amplification occurs when one peak is at its highest when the
other wave also peaks at its highest. When the two add together, the
sum is a double - hence twice the amplitude. This, of course, can
also cause problems when DJing - distortion (the signal becomes too
wide for the system). Cancellation occurs when one wave peaks and the
other valleys - 1 + -1 = 0. You have a completely flat wave form.
Silence.

The reason why you hear this especially with bass drums is because
bass is differentiated from high pitches because of it's frequency.
The less frequently the wave peaks, the lower the sound is in pitch
(or the more blue color appears, the lower on the radio dial, etc).
Well, bass drum waveforms have a very low frequency - sometimes as low
as twenty peaks in a whole second (or one peak every fifty
milliseconds, or 20hz, or twenty cycles per second). So if you add
two bass drums -out of phase- you can be off by nearly twenty-five
milliseconds in either direction and still end up with cancellation
(or, conversely, amplification).

Two solutions have been discussed. The first, to lead or follow the
original record, is a matter of phase shift. As you slow down or
speed up the added record (very carefully), the phase will change from
being -in phase- (amplification of the bass drum) to being -out of
phase- (cancellation of the bass drum). You don't need to digitize a
track to affect phase. That's half the fun of spinning wax! And as
you change the phase relationship between the two waveforms you will
hear an effect called flanging, with no special pedals required.

On the other hand, you can adjust the volume of the incoming track.
If they are -in phase- the amplitude will increase exponentially. As
you increase the fader (which changes the amplitude of all
frequencies) the amplitude of the two bass drums will seem to get
louder very fast. When -out of phase- the two bass drums will
actually get quieter as you increase the amplitude of the incoming
wave. Get it?

So the second solution is to isolate the lower frequencies from the
higher frequencies by using your EQ. If you turn the bass down on
your incoming track, the amplitude of those frequencies becomes lower.
The lower the amplitude, the less to add or subtract to the wave a a
particular phase state. If you have a bass cut switch, try that. The
outgoing bass will stay strong, and the incoming high frequencies will
present themselves as you move the crossfader. Wait until you've
faded out the outgoing song. The high frequencies of the incoming
record will predominate - and don't worry, dancers can pick up on high
frequency rhythyms, too. But before it gets tinny and boring, jack up
the EQ or hit the cutoff switch for the incoming record (on the one)
and the bass will kick in like there's no tomorrow.

If anything, you should use the phenomenon of phase
addition/cancellation as a critical tool in beatmatching. At least
you know you're hitting on all four beats! And your turntable pitch
is perfect! Digweed, here we come. If only us breakbeat DJs could
have such luck...

I sincerely hope that this helped you by explaining both the theory
involved and a practical solution. If you have any more questions,
email me at jacksonwest@jacksonwest.com. I've posted here before, and
I'm rather verbose and informed, so check me out.

Peace out fellow DJs,

Kraft

Tomislav Crncic

In article <pan.2003.07.30.20.49.22.550178.8162@student.unsw. edu.auNOSPAM>, DJ Jules B. wrote:
> Hi people.
>
> I was wondering how you people get around phase cancellation in the mix. I
> have a select few tunes that I just can't get together without the bass
> drums cancelling each other out. No matter how I try to position the two
> tunes (ie both bang on beat or one *slightly* ahead, they still end up
> cancelling each other out - any suggestions?

well, that's why equalizers are on every single mixer.

--
Tech Support: "I need you to boot the computer."
Customer: (THUMP! Pause.) "No, that didn't help."

Jackson West

>> I have a select few tunes that I just can't get together without
the bass drums cancelling each other out.

> Kill the bass on one of the tracks.
>
> Or record one of them to a PC, reverse the phase and burn to CD.

I agree with the above solution entirely. Do you understand the
principle behind phase cancellation? Remember high school trig or
calculus? If you'll sit down and read a minute I'll explain what's
going on and you can make your own decision as how best to rectify the
situation.

When you take two waveforms, or sine waves, and add (mix) them, there
is a very basic mathematical principle at work. What do you get when
you add -1 to 1? 0. What do you get when you add -.5 to .5? 0. How
about adding 2 and 2? Well, here we get a bigger number than either,
4. Over time the waveform fluctuates from between 0, full positive,
0, and then full negative. The distance it travels from full positive
to full negative is called the amplitude. The number of times it
crosses 0 in a given period of time is called the frequency.

Sound familiar? It should. It's basic wave theory, and all audible
sound is composed of the oscillation (or waves) of air pressure. On
the atomic level! Who knew DJs could be physicists!?

Now remember your wave from high school. A wave is a squiggly, but
regular, line that rises and falls vertically while travelling over a
horizontal path. The density of matter (air pressure) is represented
vertically. The horizontal axis represents time. You can measure the
median air pressure in a space very easily. But it's the minute
fluctations which create sound. Sound Pressure Level, or SPL, is
measured in decibels, for instance. This represents amplitude. A
tuning device, on the other hand, measures the frequency that the
amplitude changes - in other words, pitch.

Newton was the first to codify calculus, and to a certain extent you
could consider him the first to consider sound in the realm of
physics. Honestly. Before then it was entirely taken for granted.
Well when calculus was invented we now had a clear mathematical system
for adding, subtracting, multiplying and dividing waves (and other
continuous, curved forms). Because what can we really know about a
wave? Only how high it peaks (amplitude) and how often it peaks
(frequency). But in between it could be any number of values. It's a
curve, fer chrissake. Although if it wasn't for geometry or
trigonometry, calculus couldn't exist, it was calculus that created
the first mathematical tools for dealing with real-time fluctation in
values (change over time, delta y over delta x).

I hope I haven't lost you. To me, this shit is gold. It's probably
why I'm not a famous and succesful DJ, but hey, we all have something
to contribute. If you haven't fallen asleep, let me continue...

So what happens when you add two waves? Well, it all depends on the
frequency and the amplitude of the respective waves. In your case,
their basically the same - the TD808 bass drum wave added in equal
parts to another TD808 wave will possess one of two qualities - phase
amplification or phase cancellation.

Phase amplification occurs when one peak is at its highest when the
other wave also peaks at its highest. When the two add together, the
sum is a double - hence twice the amplitude. This, of course, can
also cause problems when DJing - distortion (the signal becomes too
wide for the system). Cancellation occurs when one wave peaks and the
other valleys - 1 + -1 = 0. You have a completely flat wave form.
Silence.

The reason why you hear this especially with bass drums is because
bass is differentiated from high pitches because of it's frequency.
The less frequently the wave peaks, the lower the sound is in pitch
(or the more blue color appears, the lower on the radio dial, etc).
Well, bass drum waveforms have a very low frequency - sometimes as low
as twenty peaks in a whole second (or one peak every fifty
milliseconds, or 20hz, or twenty cycles per second). So if you add
two bass drums -out of phase- you can be off by nearly twenty-five
milliseconds in either direction and still end up with cancellation
(or, conversely, amplification).

Two solutions have been discussed. The first, to lead or follow the
original record, is a matter of phase shift. As you slow down or
speed up the added record (very carefully), the phase will change from
being -in phase- (amplification of the bass drum) to being -out of
phase- (cancellation of the bass drum). You don't need to digitize a
track to affect phase. That's half the fun of spinning wax! And as
you change the phase relationship between the two waveforms you will
hear an effect called flanging, with no special pedals required.

On the other hand, you can adjust the volume of the incoming track.
If they are -in phase- the amplitude will increase exponentially. As
you increase the fader (which changes the amplitude of all
frequencies) the amplitude of the two bass drums will seem to get
louder very fast. When -out of phase- the two bass drums will
actually get quieter as you increase the amplitude of the incoming
wave. Get it?

So the second solution is to isolate the lower frequencies from the
higher frequencies by using your EQ. If you turn the bass down on
your incoming track, the amplitude of those frequencies becomes lower.
The lower the amplitude, the less to add or subtract to the wave a a
particular phase state. If you have a bass cut switch, try that. The
outgoing bass will stay strong, and the incoming high frequencies will
present themselves as you move the crossfader. Wait until you've
faded out the outgoing song. The high frequencies of the incoming
record will predominate - and don't worry, dancers can pick up on high
frequency rhythyms, too. But before it gets tinny and boring, jack up
the EQ or hit the cutoff switch for the incoming record (on the one)
and the bass will kick in like there's no tomorrow.

If anything, you should use the phenomenon of phase
addition/cancellation as a critical tool in beatmatching. At least
you know you're hitting on all four beats! And your turntable pitch
is perfect! Digweed, here we come. If only us breakbeat DJs could
have such luck...

I sincerely hope that this helped you by explaining both the theory
involved and a practical solution. If you have any more questions,
email me at jacksonwest@jacksonwest.com. I've posted here before, and
I'm rather verbose and informed, so check me out.

Peace out fellow DJs,

Kraft

Tomislav Crncic

In article <pan.2003.07.30.20.49.22.550178.8162@student.unsw. edu.auNOSPAM>, DJ Jules B. wrote:
> Hi people.
>
> I was wondering how you people get around phase cancellation in the mix. I
> have a select few tunes that I just can't get together without the bass
> drums cancelling each other out. No matter how I try to position the two
> tunes (ie both bang on beat or one *slightly* ahead, they still end up
> cancelling each other out - any suggestions?

well, that's why equalizers are on every single mixer.

--
Tech Support: "I need you to boot the computer."
Customer: (THUMP! Pause.) "No, that didn't help."

Tomislav Crncic

In article <pan.2003.07.31.17.16.26.207332.10567@student.unsw .edu.auNOSPAM>, DJ Jules B. wrote:
> On Thu, 31 Jul 2003 17:01:39 +1000, Tomislav Crncic wrote:
>
>> well, that's why equalizers are on every single mixer.
>
> Yes, I realise that ;-) I probably should have added "without killing all
> the bass and making the mix tinny" The problem was with two tracks in
> particular that I just couldn't get to happen without the bass dying, no
> matter what I tried.

you never kill bass on both tracks, just one because your mix gets
too boomy or it loses bass because of cancellation. you don't want
it to get too boomy bevcause you will kill the sound system if
it doesn't have limiting or the mix will sound lousy when the
limiter kicks in or your mixer starts distorting the sound.
you don+t really want that to happen, do you?
but, it depends on the music you mix.
i mix trance and there is what works for me:
match the pitch as good as you can, set the gains properly,
then kill all the frequency bands using your eq on the track
you are about to mix in, and when you pull the fader all the way up,
exchange eq position between the two tracks, like you use bass and
highs of one track with the mids of the second track.

--
Tech Support: "I need you to boot the computer."
Customer: (THUMP! Pause.) "No, that didn't help."

Tomislav Crncic

In article <pan.2003.07.31.17.16.26.207332.10567@student.unsw .edu.auNOSPAM>, DJ Jules B. wrote:
> On Thu, 31 Jul 2003 17:01:39 +1000, Tomislav Crncic wrote:
>
>> well, that's why equalizers are on every single mixer.
>
> Yes, I realise that ;-) I probably should have added "without killing all
> the bass and making the mix tinny" The problem was with two tracks in
> particular that I just couldn't get to happen without the bass dying, no
> matter what I tried.

you never kill bass on both tracks, just one because your mix gets
too boomy or it loses bass because of cancellation. you don't want
it to get too boomy bevcause you will kill the sound system if
it doesn't have limiting or the mix will sound lousy when the
limiter kicks in or your mixer starts distorting the sound.
you don+t really want that to happen, do you?
but, it depends on the music you mix.
i mix trance and there is what works for me:
match the pitch as good as you can, set the gains properly,
then kill all the frequency bands using your eq on the track
you are about to mix in, and when you pull the fader all the way up,
exchange eq position between the two tracks, like you use bass and
highs of one track with the mids of the second track.

--
Tech Support: "I need you to boot the computer."
Customer: (THUMP! Pause.) "No, that didn't help."

Experiment 5

Actually, if phase IS the problem, and we know the most dominant frequency
(it MUST be more than 40Hz), we can calculate how much we need to run one
out of time relative to the other. Since frequency is the inverse of time
(1/x), we just divide 1 by 40 an get 0.025s or 25 milliseconds.
But wait! that is the time for a full cycle. To change phase you need to
pull it back by half a cycle - 12.5 milliseconds. I don't think any DJ can
be that accurate ( or even notice.). At 500hz you need to judge it by 1mS.
So ********* it can't be simple phase cancellation.******

When I tune my bass I judge the closeness by listening to the phase
differences. A difference of 1Hz will go quiet-then loud once every second.
At 5 Hz difference you hardly notice (except it out of tune). I think this
gives us the real answer. The drums are Nearly the same frequency but not
quite. Each pair of samples starts out of phase and then wanders inut over
the course of a beat. (Or the other way round). So it sounds compressed.

Answer: remix with different drums

Homework: use Fruity loops to make 2 identical samples. Burn them to 2
CDs. Try to mix them in unison.
Dx
--
Its a bass thing - WWW.Meggastuf,freeserve.co.uk

"Jackson West" <jacksonwest@onebox.com> wrote in message
news:94593336.0307301936.7b024c0d@posting.google.c om...
> >> I have a select few tunes that I just can't get together without
> the bass drums cancelling each other out.
>
> > Kill the bass on one of the tracks.
> >
> > Or record one of them to a PC, reverse the phase and burn to CD.
>
> I agree with the above solution entirely. Do you understand the
> principle behind phase cancellation? Remember high school trig or
> calculus? If you'll sit down and read a minute I'll explain what's
> going on and you can make your own decision as how best to rectify the
> situation.
>
> When you take two waveforms, or sine waves, and add (mix) them, there
> is a very basic mathematical principle at work. What do you get when
> you add -1 to 1? 0. What do you get when you add -.5 to .5? 0. How
> about adding 2 and 2? Well, here we get a bigger number than either,
> 4. Over time the waveform fluctuates from between 0, full positive,
> 0, and then full negative. The distance it travels from full positive
> to full negative is called the amplitude. The number of times it
> crosses 0 in a given period of time is called the frequency.
>
> Sound familiar? It should. It's basic wave theory, and all audible
> sound is composed of the oscillation (or waves) of air pressure. On
> the atomic level! Who knew DJs could be physicists!?
>
> Now remember your wave from high school. A wave is a squiggly, but
> regular, line that rises and falls vertically while travelling over a
> horizontal path. The density of matter (air pressure) is represented
> vertically. The horizontal axis represents time. You can measure the
> median air pressure in a space very easily. But it's the minute
> fluctations which create sound. Sound Pressure Level, or SPL, is
> measured in decibels, for instance. This represents amplitude. A
> tuning device, on the other hand, measures the frequency that the
> amplitude changes - in other words, pitch.
>
> Newton was the first to codify calculus, and to a certain extent you
> could consider him the first to consider sound in the realm of
> physics. Honestly. Before then it was entirely taken for granted.
> Well when calculus was invented we now had a clear mathematical system
> for adding, subtracting, multiplying and dividing waves (and other
> continuous, curved forms). Because what can we really know about a
> wave? Only how high it peaks (amplitude) and how often it peaks
> (frequency). But in between it could be any number of values. It's a
> curve, fer chrissake. Although if it wasn't for geometry or
> trigonometry, calculus couldn't exist, it was calculus that created
> the first mathematical tools for dealing with real-time fluctation in
> values (change over time, delta y over delta x).
>
> I hope I haven't lost you. To me, this shit is gold. It's probably
> why I'm not a famous and succesful DJ, but hey, we all have something
> to contribute. If you haven't fallen asleep, let me continue...
>
> So what happens when you add two waves? Well, it all depends on the
> frequency and the amplitude of the respective waves. In your case,
> their basically the same - the TD808 bass drum wave added in equal
> parts to another TD808 wave will possess one of two qualities - phase
> amplification or phase cancellation.
>
> Phase amplification occurs when one peak is at its highest when the
> other wave also peaks at its highest. When the two add together, the
> sum is a double - hence twice the amplitude. This, of course, can
> also cause problems when DJing - distortion (the signal becomes too
> wide for the system). Cancellation occurs when one wave peaks and the
> other valleys - 1 + -1 = 0. You have a completely flat wave form.
> Silence.
>
> The reason why you hear this especially with bass drums is because
> bass is differentiated from high pitches because of it's frequency.
> The less frequently the wave peaks, the lower the sound is in pitch
> (or the more blue color appears, the lower on the radio dial, etc).
> Well, bass drum waveforms have a very low frequency - sometimes as low
> as twenty peaks in a whole second (or one peak every fifty
> milliseconds, or 20hz, or twenty cycles per second). So if you add
> two bass drums -out of phase- you can be off by nearly twenty-five
> milliseconds in either direction and still end up with cancellation
> (or, conversely, amplification).
>
> Two solutions have been discussed. The first, to lead or follow the
> original record, is a matter of phase shift. As you slow down or
> speed up the added record (very carefully), the phase will change from
> being -in phase- (amplification of the bass drum) to being -out of
> phase- (cancellation of the bass drum). You don't need to digitize a
> track to affect phase. That's half the fun of spinning wax! And as
> you change the phase relationship between the two waveforms you will
> hear an effect called flanging, with no special pedals required.
>
> On the other hand, you can adjust the volume of the incoming track.
> If they are -in phase- the amplitude will increase exponentially. As
> you increase the fader (which changes the amplitude of all
> frequencies) the amplitude of the two bass drums will seem to get
> louder very fast. When -out of phase- the two bass drums will
> actually get quieter as you increase the amplitude of the incoming
> wave. Get it?
>
> So the second solution is to isolate the lower frequencies from the
> higher frequencies by using your EQ. If you turn the bass down on
> your incoming track, the amplitude of those frequencies becomes lower.
> The lower the amplitude, the less to add or subtract to the wave a a
> particular phase state. If you have a bass cut switch, try that. The
> outgoing bass will stay strong, and the incoming high frequencies will
> present themselves as you move the crossfader. Wait until you've
> faded out the outgoing song. The high frequencies of the incoming
> record will predominate - and don't worry, dancers can pick up on high
> frequency rhythyms, too. But before it gets tinny and boring, jack up
> the EQ or hit the cutoff switch for the incoming record (on the one)
> and the bass will kick in like there's no tomorrow.
>
> If anything, you should use the phenomenon of phase
> addition/cancellation as a critical tool in beatmatching. At least
> you know you're hitting on all four beats! And your turntable pitch
> is perfect! Digweed, here we come. If only us breakbeat DJs could
> have such luck...
>
> I sincerely hope that this helped you by explaining both the theory
> involved and a practical solution. If you have any more questions,
> email me at jacksonwest@jacksonwest.com. I've posted here before, and
> I'm rather verbose and informed, so check me out.
>
> Peace out fellow DJs,
>
> Kraft

Experiment 5

Actually, if phase IS the problem, and we know the most dominant frequency
(it MUST be more than 40Hz), we can calculate how much we need to run one
out of time relative to the other. Since frequency is the inverse of time
(1/x), we just divide 1 by 40 an get 0.025s or 25 milliseconds.
But wait! that is the time for a full cycle. To change phase you need to
pull it back by half a cycle - 12.5 milliseconds. I don't think any DJ can
be that accurate ( or even notice.). At 500hz you need to judge it by 1mS.
So ********* it can't be simple phase cancellation.******

When I tune my bass I judge the closeness by listening to the phase
differences. A difference of 1Hz will go quiet-then loud once every second.
At 5 Hz difference you hardly notice (except it out of tune). I think this
gives us the real answer. The drums are Nearly the same frequency but not
quite. Each pair of samples starts out of phase and then wanders inut over
the course of a beat. (Or the other way round). So it sounds compressed.

Answer: remix with different drums

Homework: use Fruity loops to make 2 identical samples. Burn them to 2
CDs. Try to mix them in unison.
Dx
--
Its a bass thing - WWW.Meggastuf,freeserve.co.uk

"Jackson West" <jacksonwest@onebox.com> wrote in message
news:94593336.0307301936.7b024c0d@posting.google.c om...
> >> I have a select few tunes that I just can't get together without
> the bass drums cancelling each other out.
>
> > Kill the bass on one of the tracks.
> >
> > Or record one of them to a PC, reverse the phase and burn to CD.
>
> I agree with the above solution entirely. Do you understand the
> principle behind phase cancellation? Remember high school trig or
> calculus? If you'll sit down and read a minute I'll explain what's
> going on and you can make your own decision as how best to rectify the
> situation.
>
> When you take two waveforms, or sine waves, and add (mix) them, there
> is a very basic mathematical principle at work. What do you get when
> you add -1 to 1? 0. What do you get when you add -.5 to .5? 0. How
> about adding 2 and 2? Well, here we get a bigger number than either,
> 4. Over time the waveform fluctuates from between 0, full positive,
> 0, and then full negative. The distance it travels from full positive
> to full negative is called the amplitude. The number of times it
> crosses 0 in a given period of time is called the frequency.
>
> Sound familiar? It should. It's basic wave theory, and all audible
> sound is composed of the oscillation (or waves) of air pressure. On
> the atomic level! Who knew DJs could be physicists!?
>
> Now remember your wave from high school. A wave is a squiggly, but
> regular, line that rises and falls vertically while travelling over a
> horizontal path. The density of matter (air pressure) is represented
> vertically. The horizontal axis represents time. You can measure the
> median air pressure in a space very easily. But it's the minute
> fluctations which create sound. Sound Pressure Level, or SPL, is
> measured in decibels, for instance. This represents amplitude. A
> tuning device, on the other hand, measures the frequency that the
> amplitude changes - in other words, pitch.
>
> Newton was the first to codify calculus, and to a certain extent you
> could consider him the first to consider sound in the realm of
> physics. Honestly. Before then it was entirely taken for granted.
> Well when calculus was invented we now had a clear mathematical system
> for adding, subtracting, multiplying and dividing waves (and other
> continuous, curved forms). Because what can we really know about a
> wave? Only how high it peaks (amplitude) and how often it peaks
> (frequency). But in between it could be any number of values. It's a
> curve, fer chrissake. Although if it wasn't for geometry or
> trigonometry, calculus couldn't exist, it was calculus that created
> the first mathematical tools for dealing with real-time fluctation in
> values (change over time, delta y over delta x).
>
> I hope I haven't lost you. To me, this shit is gold. It's probably
> why I'm not a famous and succesful DJ, but hey, we all have something
> to contribute. If you haven't fallen asleep, let me continue...
>
> So what happens when you add two waves? Well, it all depends on the
> frequency and the amplitude of the respective waves. In your case,
> their basically the same - the TD808 bass drum wave added in equal
> parts to another TD808 wave will possess one of two qualities - phase
> amplification or phase cancellation.
>
> Phase amplification occurs when one peak is at its highest when the
> other wave also peaks at its highest. When the two add together, the
> sum is a double - hence twice the amplitude. This, of course, can
> also cause problems when DJing - distortion (the signal becomes too
> wide for the system). Cancellation occurs when one wave peaks and the
> other valleys - 1 + -1 = 0. You have a completely flat wave form.
> Silence.
>
> The reason why you hear this especially with bass drums is because
> bass is differentiated from high pitches because of it's frequency.
> The less frequently the wave peaks, the lower the sound is in pitch
> (or the more blue color appears, the lower on the radio dial, etc).
> Well, bass drum waveforms have a very low frequency - sometimes as low
> as twenty peaks in a whole second (or one peak every fifty
> milliseconds, or 20hz, or twenty cycles per second). So if you add
> two bass drums -out of phase- you can be off by nearly twenty-five
> milliseconds in either direction and still end up with cancellation
> (or, conversely, amplification).
>
> Two solutions have been discussed. The first, to lead or follow the
> original record, is a matter of phase shift. As you slow down or
> speed up the added record (very carefully), the phase will change from
> being -in phase- (amplification of the bass drum) to being -out of
> phase- (cancellation of the bass drum). You don't need to digitize a
> track to affect phase. That's half the fun of spinning wax! And as
> you change the phase relationship between the two waveforms you will
> hear an effect called flanging, with no special pedals required.
>
> On the other hand, you can adjust the volume of the incoming track.
> If they are -in phase- the amplitude will increase exponentially. As
> you increase the fader (which changes the amplitude of all
> frequencies) the amplitude of the two bass drums will seem to get
> louder very fast. When -out of phase- the two bass drums will
> actually get quieter as you increase the amplitude of the incoming
> wave. Get it?
>
> So the second solution is to isolate the lower frequencies from the
> higher frequencies by using your EQ. If you turn the bass down on
> your incoming track, the amplitude of those frequencies becomes lower.
> The lower the amplitude, the less to add or subtract to the wave a a
> particular phase state. If you have a bass cut switch, try that. The
> outgoing bass will stay strong, and the incoming high frequencies will
> present themselves as you move the crossfader. Wait until you've
> faded out the outgoing song. The high frequencies of the incoming
> record will predominate - and don't worry, dancers can pick up on high
> frequency rhythyms, too. But before it gets tinny and boring, jack up
> the EQ or hit the cutoff switch for the incoming record (on the one)
> and the bass will kick in like there's no tomorrow.
>
> If anything, you should use the phenomenon of phase
> addition/cancellation as a critical tool in beatmatching. At least
> you know you're hitting on all four beats! And your turntable pitch
> is perfect! Digweed, here we come. If only us breakbeat DJs could
> have such luck...
>
> I sincerely hope that this helped you by explaining both the theory
> involved and a practical solution. If you have any more questions,
> email me at jacksonwest@jacksonwest.com. I've posted here before, and
> I'm rather verbose and informed, so check me out.
>
> Peace out fellow DJs,
>
> Kraft