tchampion Mar 06, 2014 11:01 am
Hi there,
I have the following equipment in my set up: 2x SC-2900 1x Pioneer DJM 800 Traktor Scratch Pro 2.6 running on a Macbook Retina (mid 2013)
I would like to use the DJM 800 as external mixer for pre-listening and mixing and the SC 2900’s as the controllers. So both SC 2900’s are connected to the mixer via RCA plugs and to the Macbook via USB. I aggregated both SC2900’s in one sound device which is the device used in Traktor in the Audio setup panel. Running both SC2900 in normal mode MIDI mode in Traktor I have managed to get everything up and running. However,after playing a couple of songs the songs on one of the players start to sound distorted.
I thought that it might have something to do with the latency setting, which is by default 512 and gives 13.6ms. Increasing the latency solves the problem temporarily because after a while the distorted sound starts to appear again… 
The SC2900 have the latest firmware installed.
Please help me what to do!
DJ_Boothe Mar 06, 2014 7:53 pm
When you say “after a while” how long roughly does the sound take to go distorted again?
Try this:
Switch the lappy off for over an hour, so it cools entirely.
Switch back on, let a playlist run
Time how many minutes go by before the sound starts to distort.
Switch the lappy off for over an hour, to cool it again.
Change the latency to the lower/quicker setting
let a playlist run
time how long.
tchampion Mar 10, 2014 2:24 pm
On the mentioned setting of 512 the distorted sound appears after 25 minutes… Changing it to a lower/quicker setting of 256 results in a distorted sound after only 10 minutes
DJ_Double_A Mar 07, 2015 9:14 pm
Sounds like it may be a heat issue. I would first try cleaning out all the cooling/vent holes on the Mac. Any type of dust build up can hinder the computer’s cooling efficiency. If it improves after cleaning but still distorts after a certain amount of time, I would look into getting a laptop cooler of some kind.
DJ_Boothe Mar 07, 2015 10:29 pm
Agreed. Sounds like hot vs cold latency.
If you let the lappy cool down (by switching it off for an hour+) then restart it, does the noise disappear and take 20 plus minutes to come back?
If so it’s hot latency versus cold latency. Increase your latency setting to a point where everything sounds ok even when the lappy heats up
Mark82 Mar 11, 2015 6:47 am
Yep even after leaving it over night Will select a higher latency tonight Thanks for your help
Tested last night at 1024 23.2ms latency All was fine untill just after the 2 hour mark then noise was back but only in left deck, change to right deck and sound was fine, back to left, crackle
DJ_Boothe Mar 12, 2015 7:56 am
The fact that you changed latency and managed to change the issue, certainly focuses the problem on processing power/latency.
Try labelling the USB ports … A, B, C etc - now swap the USB ports which each of the two decks plugs into.
Let the whole system cool for hours then switch back on a repeat the test - which USB port is the first to start crackling as the lappy heats up?
Also be mindful of trying to use USB ports which are on different sides of the lappy - lappys are well known for having different types of USB ports on them in a general mixture of USB 2 or 3, powered vs unpowered, hubbed internally or real individual USB ports - some USB ports only worked fully if a heavy duty power supply was purchased instead of the standard lightweight power supply which the lappy shipped with.
Also, are the USB leads identical for each deck - excessively long leads can highlight issues.
Mark82 Mar 12, 2015 10:01 am
Used 3 sets of identical leads Only have usb on left side and 2 ports i have tried with a powered hub and same thing hapens. I will switch ports tonight and see what hapens
SirReal Mar 12, 2015 5:08 pm
Is this a possible USB3 issue? Have you tried using a USB2 hub?
Mark82 Mar 12, 2015 5:50 pm Just switched cdjs round, lasted 15 mins before noise was back. Loaded same song on both decks, noise on both, loaded earlier track with no noisecand noise this time. Set it at 512 11.6ms no smc fan controll tonight
DJ_Boothe Mar 12, 2015 8:27 pm Re: Noise issue You mentioned previously the latency problem appeared on one deck… When you swapped the decks over between one USB port then the other USB port, did the latency sound stay on the same USB port?
Mark82 Mar 12, 2015 8:39 pm
Used usb port closest to screen and noise in both decks Usb port closest to me noise in left deck I am checking this as we speak so will report back shortly
Mark82 Mar 12, 2015 9:10 pm
Swapped leads in players and noise in right deck Hub in port nearest me
DJ_Boothe Mar 13, 2015 7:37 am Re: Noise issue Ditch the USB hub.
Every USB port has an “address” an order in which its looked at by the lappy. I suspect when the lappy slows down due to its ways of reducing processing heat, it favours one USB port more than the other - not because of any shutting down of a USB port, but just down to how often it can check the port within the cycles set by too low a latency.
Having said that, finding out if USB port A or B crackles at very low latency doesn’t help solve the issue, so either way, you’ll need to improve the performance of the lappy, give it less to think about (lower quality settings), get a higher performance lappy, or increase the latency setting to a level that the usbs can cope with even when the lappys hot and running on reduced processing “umph”
Ultrac Jun 20, 2015 6:38 am
In my case when I removed the Semi Display A.tsi and Semi Display B.tsi the noise is stopping. You will on;y loose the display. Read viewtopic.php?t=21372
DJ_Boothe
Jun 20, 2015 7:32 am
Sounds like it was a latency / lappy performance issue then - the pointless cosmetic duplication of info already shown in the lappy screen really grinds processor performance and adds latency, which makes sound cards grumble.
I wonder more and more whether lappys and DJing should ever be thought of as a viable “solution”