Sound quality problems

Message

Haydn · #1 Post by **Haydn** » Wed Apr 19, 2006 9:26 am

I've DJ'd twice with my Numark CD Mix 2 deck, and suffered from poor sound quality both times For reference, this is the CD Mix 2 -
http://www.amazon.com/gp/product/B0000C ... e&n=172282

I bought the CD Mix 2 second-hand, and everything seems to work properly. I mix my own CDs via iTunes on an iMac, ripping tracks using AAC at 192 bit rate. I connect to an external amp using the twin RCA sockets at the back. The first time I DJ'd I connected to another DJ's amp. The second time, I connected to the club's own amp. Both times I was disappointed with the sound quality. It sounded rough and distorted. By adjusting the controls, I managed to improve it a bit, but it still wasn't great. The sound has been better when I have used other peoples' decks.

Any ideas?

CafeSavoy · #2 Post by **CafeSavoy** » Wed Apr 19, 2006 1:13 pm

You might try connecting the mixer to the amp using the other set of outputs (xlr).

Mr Awesomer · #3 Post by **Mr Awesomer** » Wed Apr 19, 2006 1:29 pm

You may also want to try making your mixed CDs from wav files.

From what your wrote it sounds like you're compressing your music when making ACC files, then expanding them again when making the mixed CD. This never bodes well for sound quality.

Matthew · #4 Post by **Matthew** » Wed Apr 19, 2006 3:15 pm

It could also be a mix of things. Could you describe the sound a bit more?

It might help to set up early once and test things out. I'm certainly no expert in sound equipment, but here's some stuff I'd try:

Play an original CD

Check all connections

Use well-shielded cables

Play a CD that's been burned at 4x or slower

Adjust the EQ by turning things down, rather than up (if it sounds too boomy, turn down the bass instead of turning up the treble)

Find an example of the sound you don't want, then pause the track there and listen to it frame by frame.

Bob the Builder · #5 Post by **Bob the Builder** » Thu Apr 20, 2006 3:14 am

Hi Huey,

That CD player / mixer should be very good. What everyone says so far is spot on.
It is very important when testing sound systems that you have only one item being tested at most. With sound equipment you have to be through. I would be surprised if it is the mixer is the problem.

First thing is to know your equipment. Make sure you read through the user manual for the consol. When testing make sure you have all the effects on the mixer turned off or in the level position. That included the equalizers, gain, pitch control, cross fader, looping and mono.
Second ensure you are using an original CD for doing your test. Can I recommend you use “The complete Atomic Basie” (Count Basie off the Roulette label) for you sound check. Before doing you sound check, run a CD laser light cleaner on both CD players.
In the first sound check listen directly through the head phone jack, with a good pair of DJ grade head phones, that you know work well. Test both player through it.
If that works well, you can go on and check your master outputs.
Your system has both balanced and unbalanced outputs. Balanced is much better. You can run a balanced cable up to 50 meters and you won’t get much loss in signal quality.
Balanced cables are ¼ inch phone type, and to the ordinarily person they will look like a stereo type cable. You will need two of these cables (one of the left channel and one for the right channel). Make sure you plug them into the right socket.

Like I said before, make sure you know the amp and sound system you are going to test on are in full working order before the test.

Happy testing

Brian

Haydn · #6 Post by **Haydn** » Thu Apr 20, 2006 7:43 am

Thanks a lot for the feedback everyone.

Brian and Rayned, you both suggested using the 'balanced' XLR outputs from the deck. These are two big round sockets like these - http://www.answers.com/topic/xlr-connector

The Numark CD Mix 2 manual (available in the support section of Numark's website http://numark.com/) describes them as:
"Stereo Balanced Master Outputs (XLR): lowimpedance XLR type connectors controlled by the Master fader"

The RCA output connectors are described as:
"Master Output (RCA): This output is for connecting an external monitoring device such as a PA system, powered monitors, or a home stereo. The level of the master stereo output signal is controlled by the master fader."

I did originally buy XLR cables to connect the CD Mix 2 to the powered speakers I use at home, but it didn't work (no sound). When I last bought a cable to go from the CD deck to an amp, the sound equipment shop told me to run a cable from the RCA sockets. I think they said that the XLR sockets were meant for a 'big PA system'.

Numark's description of the sockets doesn't make it clear which to use for DJing, although they do say to use the RCA outputs for powered speakers.

From what you say, I should use the XLR outputs for DJ work. So when I am working in the club with RCA inputs on its' amp, I will need two 'balanced' XLR to RCA cables. To connect to my powered speakers at home, I'll try using the RCA jacks, because the cable from the XLR sockets didn't work.

I'll let you know the outcome.

Haydn · #7 Post by **Haydn** » Thu Apr 20, 2006 7:50 am

GuruReuben wrote:You may also want to try making your mixed CDs from wav files.

From what your wrote it sounds like you're compressing your music when making ACC files, then expanding them again when making the mixed CD. This never bodes well for sound quality.

I don't think this is the problem, but I'll test the set-up thoroughly with an original CD.

Haydn · #8 Post by **Haydn** » Thu Apr 20, 2006 7:53 am

Matthew wrote:It could also be a mix of things. Could you describe the sound a bit more?

It might help to set up early once and test things out. I'm certainly no expert in sound equipment, but here's some stuff I'd try:

Play an original CD

Check all connections

Use well-shielded cables

Play a CD that's been burned at 4x or slower

Adjust the EQ by turning things down, rather than up (if it sounds too boomy, turn down the bass instead of turning up the treble)

Find an example of the sound you don't want, then pause the track there and listen to it frame by frame.

Thanks Matthew, I'm going to try and get there early next week with an original CD and test the sound thoroughly.

Bob the Builder · #9 Post by **Bob the Builder** » Fri Apr 21, 2006 1:46 am

Hmmm, Huey, I see how you are getting confused.

RCA cables are always Un-balanced

XLR and ¼ phono TRS, can be used in a Balanced or Un-Balanced format.
XLR and ¼ phono TRS are the exact same cables, its just the sockets are different.
You mixer spec, say its has a Balanced output. I would be surprised if it wasn’t ¼ phone TRS. Sending yours sound signals from your mixer to the PA system using a balanced circuit is the professional way to send the signal. What you will find is that many of the smaller off the shelf “DJ” mixers don’t have a balanced output, in which case you end up using Un-balanced.
Have a look at this website. link. I'm sure there is loads of other sites out there. And as I said before. Make sure you read your mixer user manual. It will give you a full understanding of your systems outputs.

Brian

Toon Town Dave · #10 Post by **Toon Town Dave** » Fri Apr 21, 2006 5:14 pm

IIRC, the CD-MIX2 has both XLR and RCA outputs and I believe the RCA is labelled tape-out or something like that. The only times I've encoutered the MIX2's DJing, the speakers were conected with XLR and it just worked. The sound seemed fine unless the eq was tuned stupidly (eg bass way up). If your XLR connectors aren't working and it's not something obvious like a busted cable, I'd have the unit checked out.

I've never tried the RCA outputs but I can't imagine them sounding much different than the XLR unless you have a nice long run of unshielded, untwisted cable through a noisy (EM) environement.

Haydn · #11 Post by **Haydn** » Sun Apr 23, 2006 8:50 am

Bob the Builder wrote:Hmmm, Huey, I see how you are getting confused.

RCA cables are always Un-balanced

XLR and ¼ phono TRS, can be used in a Balanced or Un-Balanced format.
XLR and ¼ phono TRS are the exact same cables, its just the sockets are different.
You mixer spec, say its has a Balanced output. I would be surprised if it wasn’t ¼ phone TRS. Sending yours sound signals from your mixer to the PA system using a balanced circuit is the professional way to send the signal. What you will find is that many of the smaller off the shelf “DJ” mixers don’t have a balanced output, in which case you end up using Un-balanced.
Have a look at this website. link. I'm sure there is loads of other sites out there. And as I said before. Make sure you read your mixer user manual. It will give you a full understanding of your systems outputs.

Brian

I bought a twin-RCA to twin 1/4" cable from a Pro Audio shop. The man in the shop said that RCA wasn't balanced, so the cable isn't. As far as I can see, if I connect from the balanced 1/4" output on the CD Mix 2 to RCA inputs on the amplifier, the connection (circuit?) will be unbalanced. Presumably, then, the only way to get a balanced connection or circuit is to connect from a balanced output on the mixer to a balanced input on the amp, and using a balanced cable. So, perhaps I should see if there's a balanced input on the amp?

Anyhow, I'm going to thoroughly check the sound this Tuesday, and let you know the outcome.

Toon Town Dave · #12 Post by **Toon Town Dave** » Sun Apr 23, 2006 12:57 pm

You can purchase "adapters" to go to/from balanced and unbalanced. Some (cheap ones) probaby just hook fiddle with the wires. The more expensive ones should do it the proper way and use a transformer inside the adapter. They are quite expensive and you could probably come up with a DIY solution. Google for "balun", "audio balun" or "balun transformer" and you should find a few parts or hacks. Baluns are quite common in RF circuits but the principle is the same for baseband audio.

Bob the Builder · #13 Post by **Bob the Builder** » Mon Apr 24, 2006 2:23 am

huey wrote: the only way to get a balanced connection or circuit is to connect from a balanced output on the mixer to a balanced input on the amp, and using a balanced cable. So, perhaps I should see if there's a balanced input on the amp?

Spot on.

All amps should have a balanced input be that 1/4 inch TRS or XLR. Only domestic and very shity amps don't.

Haydn · #14 Post by **Haydn** » Mon Apr 24, 2006 6:18 am

Bob the Builder wrote:
huey wrote: the only way to get a balanced connection or circuit is to connect from a balanced output on the mixer to a balanced input on the amp, and using a balanced cable. So, perhaps I should see if there's a balanced input on the amp?

Spot on.

All amps should have a balanced input be that 1/4 inch TRS or XLR. Only domestic and very shity amps don't.

Cheers

I haven't actually seen the sockets on the amp, because it's shut away in a rack, and they've wired up a cable with two RCA jack sockets at the end to connect a deck to. So it looks as though they've made it easy to connect, but prevented the use of a balanced connection. I'll probably buy a balanced 2 x XLR" to 2 x 1/4" cable to take along, and try to get access to the actual sockets on the amp. It'll have to be a long cable, because the amp is round the back and the deck needs to be at the front, but the good thing is cable length doesn't seem to matter if it's balanced.

By the way, what does TRS stand for?

Also, Brian, following your suggestion, I'm using 'The Complete Atomic Basie' to soundcheck. I've just used track 12 (Silks and Satins) to compare the sound of the original and my iTunes imported version on my set-up at home. The good news is the iTunes version sounds fine and as good as the original, which reassures me that the quality of the tracks I'm playing is fine. I feel I am making progress understanding the issues regarding sound quality and am starting to feel confident about achieving better sound when I DJ.

Thanks again for the help.

lipi · #15 Post by **lipi** » Mon Apr 24, 2006 5:03 pm

By the way, what does TRS stand for?

tip-ring-sleeve, named after the contact points on the plug.

balanced cables have three wires and three contacts (instead of the more common two). the tip and ring carry inverted mono signals and the sleeve is ground.