“Now that I have completely bored you to death, and made your eyelids heavy you can go back to your regularly scheduled programming.”

Nope, I’m still standing, and I want more :)

As for that CD link, the website is currently belly up : “Access Denied

You don’t have permission to access “http://www.crutchfield.com/S-AolesI61Oik/App/Product/Item/Main.aspx?” on this server.
Reference #18.c14dd58.1218576938.8580551″

Is there a way to do the same thing with a testone? We’re cheap round here, you know :)

“Is there a way to use two two channel sound cards with MAC and Traktor… like aggregating them?”

Traktor manual says: ‘Multiple audio interfaces are not supported.’. Not at home for the rest of the month, so can’t check, but doing an aggregate device in Audio MIDI Setup utility may work.

“The sound quality in most of today’s laptop DJ software is much closer in quality to that of home audio gear. They lack the inverse of the equalization curve of PA speakers.”

Can’t we do that with a software EQ at the end stage? I usually put the same EQ on my two stereo out, tuned to what I hear in the room. Any link to common curves, or you just do it by ear?

Btw googling “gain structure” brought loads of interesting stuff, many many thanks for that, I didn’t know that it was called this!

I’ll come back to this moment.

In my personal opinion, if a DJ turns up the gain more than 10 dB it can be physically painful, I will hear hard clipping and distortion and it will be awful, because just when you want the music to be the clearest, it sounds the worst.

Everyone else’s comments here relate to clipping at the amplifier outputs. I think what you are commenting on his clipping before the amplifier, not after it.

You are clipping in the input stage at the preamplifier level, not the output stage at the amplifier level.

That is what is causing your harsh distortion. Saving some headroom by limiting the voltage into the amplifiers will keep the amplifiers from clipping. But once you need to do is to keep the preamplifier’s from clipping. Mostly because if the preamplifier’s clip within your DJ software program there is no way to emulate “soft clipping” like a tube amplifier. Your fire face soundcard has a bigger brother, the fire face 800 model, which has one of the inputs that has a soft clipping feature for a guitar. However it still does not sound as good as tube distortion.

That Motown sound that you are referring to is not so much clipping, as it is producers taking real care to prevent overloading the analog signal.

A lot of amplification was done with tubes back then, and they used VU meters. But more significantly amplification power was truly expensive. So sound engineers got used to using what is called “gain overlap” to get the most for their amplification dollars per per watt.

Typically they would drive, or overdrive signal no more than 2-3 dB.

There is a compact disc you can buy specifically for use in gain setting.

I suggest you get a copy of this compact disc and its instructions. What’s really great is that they play certain clips with distortion from over driving, that way you can learn to recognize the sound of clipping more readily.

You can use this disc to set gain structure throughout your system because you also have to set gain structure at the preamplifier stage as well as at the amplifier stage. In fact anywhere in the chain where you can manually increase the volume, you should set a gain level. It takes about 3-4 minutes to do this when you know what you are doing.

http://www.crutchfield.com/S-AolesI61Oik/App/Product/Item/Main.aspx?i=503CD104

You should avoid clipping in the digital domain completely. The only place where you should consider a 3 dB overlap is in the amplifier stage.

In regards to the comments about dynamic headroom. Going to a higher bit rate is not the answer. Because of thermal noise which occurs in the output stage of digital to analog converters, no matter how high bit rate, the maximum amount we can get out of the signal is 21 bits. So bit rate currently is not the answer because thermal noise will bury any theoretical headroom which was gained further upstream.

Nightclubs actually have very limited dynamic range. The noise of the patrons and the general operation of the AC really limit the lower-level of dynamic resolution. Also you don’t want to play as loud as a jet engine and injure the hearing of all of your customers and possibly yourself.

Signal-to-noise ratio, however, is really important despite the fact that you may not be able to hear the full dynamic range. Small musical nuance is lost completely when the dynamic range falls below 100 dB. Units that have over 115 DB of dynamic range have the potential to sound better. As you approach 120 dB dynamic range you really have the chance for great sound.

Lots of other things affect the sound is well, most significantly early reflection, the polar radiation pattern of the drivers used, general speaker positioning, and taking into account the actual length of the bass wave.

I think what you are hearing is not so much clipping as an issue, but that many of the mixers you liked have the inverse of the equalization curve of PA speakers. The old high quality rotary mixers of the 1980s had that curve. Because the high-end frequencies were rolled off, he didn’t get so much “high-frequency hash” if you clipped the signal. Also PA speakers of that era had notoriously harsh tweeters.

The sound quality in most of today’s laptop DJ software is much closer in quality to that of home audio gear. They lack the inverse of the equalization curve of PA speakers.

So when you clip the signal within your laptop, you are then sending clipped signal through the preamplifier, and then through your sound card — (which is actually your preamplifier in this case because the digital to analog conversion is done in your sound card) and then this distorted signal is sent to your amplifier. It remains distorted even if you do not clip your amplifier. But when you do clip your amplifier that distortion is made even worse and more audible.

Because that distortion when run through a quality rotary house mixer of the 1980s is attenuated before you feed it to the amplifier, it is not as noticeable. However, that is still not the best solution — the best solution is not to clip the signal anywhere in the audio chain.

I have one possible solution for you, it is not the end-all solution, but it may help.

I use a small hybrid tube amplifier gain stage after my sound card but before the amplifier. It works at the preamplifier level. And when I clip, and I do introduce about 3 dB of clipping, it really rounds off a high frequencies and removes that harsh glare associated with digital clipping.

If you read the manual in the CD I mentioned, you’ll see why they recommend about 3 dB of gain overlap.

Also you have to pay attention to what frequencies you are clipping. It’s really not so bad if you clip and the only sounds present our bass frequencies — but if you clip while pumping up your high frequencies — it is downright painful.

So when setting your gain overlap make sure you use songs with a lot of high frequency material so that it doesn’t sound any worse during your mix, in fact you may want to master the few tracks where you have pumped up the high frequencies and use those tracks when establishing your gain structure.

Now that I have completely bored you to death, and made your eyelids heavy you can go back to your regularly scheduled programming.

If you want one of these tube amplifier gain stages, drop me an e-mail. They are very compact, and are about the size of an iPod — and when used with Ultrasone Headphones they just sound magically good, so they have an additional use outside of the club. They sound good with just about every headphone, but there is amazing synergy with Ultrasone headphones. I use another one of these if I need more headphone gain for myself. I only have parts for about 30 more units and then they are unfortunately gone forever as they use a miniature vacuum tube that is no longer in production (when we run out of tubes- game over)- the tubes are not driven hard and at the very low voltage fed to them will last a lifetime of music. I apply a military grade scratch proof coating to them which is also chemical resistent (spilled drinks) so they stay looking nice.

It is too bad that I sell these units modified, because I sound biased. But I am happy to tell you the drawbacks. They are not cheap- about $650. They are not indestructible but the tubes are protected, and won’t get damaged even if you jogged with them. For me they solve my issues with clipping and sound far better than the RME Fireface alone. I bought the RME fireface 800 and I sold it a week later once I found these. I am now looking for even better soundcards than the RME to use further upstage of this tube buffer (and witout ahving to buy a $3000 + apogee Rosetta 800 I think i have have found some. I do get what I feel is a nicer sound than that of the older Bozak and Urei rotaries. The only issue now is making Traktor see more than one sound card as these sound cards are only 2 channel.

Is there a way to use two two channel sound cards with MAC and Traktor… like aggregating them? Then I think I have a total solution to sound quality using traktor.

@Ean - One thing to consider is the cheap fix: slowly bring down the gain on the louder track until you can equalize the levels. I’ve heard Derrick May does this in his mixes, so that it always sounds like things are getting louder when he brings in a new track.

Use the autogain. If you need to raise the gain of a track while it is playing, consider just turning up the main volume instead. You should use the track gain only to match relative tracks loudness. This way, your tracks gain won’t escalate. If you have nevertheless escalated the gain or EQs, raise the master volume while lowering the gain/eqs to get headroom back.

If you are short in master volume during the night, try raising the amp gain, if you are short on amp gain then use the tracks gain, then if it is still not enough the eq. If you got to that point, the sound system was not adapted to the situation and the sound will be lame. Consider progressively lowering the volume to let people adapt to a less loud sound, then start building up again.

1: play loudest track with auto gain off- reduce master out so it hits at approx -3db

2) load 2 loud songs in each deck with auto gain on and then reduce the gains of each -2/3 db

It seems like using auto gain in conjunction with a digital gain knob might also be partially to blame.