so much noise (and hum) from my A16 Ultra

mano · Post by **mano** » Thu May 09, 2002 8:18 pm

Until today my A16 Ultra's LEDs were barely on, until I found the DIP Switches in the back (thanks subhuman!) to switch the inputs to "Consumer -10dBv".

Well, I was getting happy because the LEDs were dancing as I was feeding audio channels through it, BUT now there is a LOT of background noise!

By this I mean if I stop my sequencer and listen, there is a pretty loud noise! The levels indicate -70dB... and the main mix level -48dB (!).

Now... If I mute all the channels on the pulsar mixer (err... now STM 2448) the noise stops. There is still a bit of a hum if I crank up the volume though.

What is going on?
Thanks in advance for all your help

[ This Message was edited by: mano1.com on 2002-05-09 21:36 ]

Post by **garyb** » Thu May 09, 2002 10:49 pm

ground loop.

mano · Post by **mano** » Fri May 10, 2002 8:05 am

I dont mean to double post threads by the way, problems arise one after the other and although they may be related my reflex is to post here to ask you guys

Sorry for the long post, I really would like to have a clean setup. Cant stand noise or hum

----------------------

Ground loop... well I figured there's that, but do you think that all the noise coming from the A16U is solely due to a ground loop? As I said its not just a "clean hum" (i know thats silly but), theres also a loud scchhhhhh noise.

What are the real solutions to such problems? I am not happy about "isolating from the ground" and tings like that, it doesnt sound natural...

I have a feeling that my computer itself is generating a lot of the noises and hums; after all the case was cheap (one of those $40 ones with built-in power supply), and if I crank up loud I can hear the CD tray going in and out, screen contents changing (from white to black generates a noise), Hard disk loading stuff... Plus the fan itself is suuuuper loud anyway.

ARGHHHHhhhh

Do you think changing my computer case would reduce all these electronic noises and or noise in general, and or hum?

I think I should list my setup, it will probably give you guys some idea of where problems arise:

. Intel machine (ie PIII 1Ghz + 815EEA motherboard) in a crappy case with an (extremely) loud fan

. Event 20/20bas monitors

. ROLLS MX28 mini-mix (to control the main volume and to plug headphones) because those damn monitors are already amplified, and because Pulsar avoid the need of a "real" mixer

. A16 Ultra

. Roland XV3080 + Access Virus B

Sources situation:

Both XV and VIRUS have unbalanced outputs. IN the A16U manual it says that there is no problem with unbalanced signals, it switches its ins and outs to balanced or unbal. as needed, apparently. SO I use a bunch of classic mono jacks to connect those to the A16U inputs.

Now my monitoring situation:

I use unbalanced RCA to jack cables to connect my Pulsar 2 to the mini-mixer. The mini-mixer has headphone plugs and outputs, plus knobs for levels... Again I needed "something" to control my volume...

I use unbalanced jacks to connect the outputs of my mini-mix to my 20/20bas. The speakers manual says that unbalanced signals are "ok"... BUT i know I should change that... Anyway, the hum is still in my headphones even if I dont plug the speakers at all.

I recently moved. I already had this problem at my old place.. Mind I didnt have the A16U yet. I was just plugging my Virus B to my Pulsar2 analog ins with a pair of cables. The problem was there though, might help to know that.

I dont mean to play with your nerves

you probably already tried to help me in other threads, but if you think you know what is going on, please post

Thanks in advance for all the help, I love planetz, and I love my Pulsar

[ This Message was edited by: mano1.com on 2002-05-10 09:15 ]

Round1 · Post by **Round1** » Fri May 10, 2002 8:24 am

What about the outputs from the A16? Be careful when going from the A16 (which is Balanced) to unbalanced. The A16's outputs are NOT fully floating. Read the A16 manual for the correct wiring. (Use a stereo 1/4 inch jack, wire + to tip, leave the ring unconnected, and shield to the sleeve). Creamware have a specific warning about this in the manual.

Post by **garyb** » Fri May 10, 2002 8:50 am

as to the wiring on the coonectors going into the a16,leaving the shield and disconnecting the ring is kinda unusual.usually, it's the other way around.(connect tip to + ring to - and leave sleeve connected at a16 end.connect shield at other end only.then at the unbalaced end use 2 conductor connector and connect tip to
+ and sleeve to - ,cutting back shield to where it doesn't connect to anything.this is the normal way to lift ground but follow the instructions w/ your a16) besides the wiring considerations,sometimes floating the ground on the ac cable of devices helps.the main thing to remember is that you can float most everything,but something must remain grounded for safety.usually it would be the mixer,or whatever the mic goes into. in this case,the computer itself would be a good thing to have grounded,any mic pres may need to be grounded also.it also helps to have everything on the same circuit.

[ This Message was edited by: garyb on 2002-05-10 09:57 ]

mano · Post by **mano** » Fri May 10, 2002 11:00 am

I just talked to someone at a music store, he suggested to get a cheap/small behringer mixer to control my speaker and headphone monitoring. It has balanced INs and OUTs and only costs $70.

I guess I could do the whole unbalanced cables + modified cables thing, it'd fix most of my problems; what do you think? This ROLLS mini-mix is all unbalanced, doesnt help.

I am not sure if I would build my own cables... Do you know a place where I could get the cables I need with the modification you mentionned? or maybe some adapters to plug at the end of each unbalanced cable coming from my Virus and XV (that's 12 cables roughly)

Then there is this noisy computer case... I have a bad feeling about it. Any suggestion?

[ This Message was edited by: mano1.com on 2002-05-10 12:07 ]

subhuman · Post by **subhuman** » Fri May 10, 2002 12:37 pm

My A16 Ultras area REALLY quiet. Much better noise floor than the Yamaha 03D they replaced...!

I did have this strange "flicker" or "distortion" on my brand new monitor - same place as the old one I replaced it with! I was frusterated. Then I moved this powerstrip full of wallwarts about 1 foot away - the problem was GONE! I was so happy to finally have a clear flicker-free monitor again.

Basically I think you must have either a ground loop (try powering everything from one outlet), or other devices placed too close to your audio cables. Try physically moving things around...

mano · Post by **mano** » Fri May 10, 2002 1:10 pm

thank you so much for posting sub, you rock

I cant wait to go home (its friday

) and play with my studio, ill unplug everything, ponder this whole thing and post here reports if anything happens

post more if you have suggestions

I think Im gonna get that cheap all-balanced behringer 602 mixer to control my monitoring.

I am a bit scared

of the way you described the cables I need to plug my unbalanced sources on balanced inputs. It'd be great if I could buy those somewhere. Sub I think you mentionned you built yours?

The electric installation in my house is pretty old (lights intensity varies, etc. scary stuff

).. I realized music stores were carrying "nice" outlets with voltage regulators and noise filtering... like this one: http://music123.com/Item/Item.asp?po=ETAPD8 or this one http://music123.com/Item/Item.asp?po=ART0219200220221

How useful do you think this would be in fixing some of my problems? For less than $100 it seems pretty sweet

[ This Message was edited by: mano1.com on 2002-05-10 17:23 ]

mano · Post by **mano** » Fri May 10, 2002 8:48 pm

quick update (i promise i wont post for a while

)

I can plug unbalanced signals to the A16Ultra inputs, the manual says that the Ultra model shortnes the ring contact to ground. Hey nice!

But you are right for the OUTs: the manual says to use only stereo (ie balanced) cables for the OUTPUTS --- which I wasnt doing, hence the source of most of my problems!

So... heres what I am going to do:

. I will keep using unbalanced cables to plug my virus and XV to my A16U (read above about Ultra model)

. I will get a 100% balanced Behringer 602 to control my monitoring (speakers + headphones)

. I will get 2 stereo jacks (balanced) to connect 2 outs from the A16U to the behringer, and another pair to plug the 20/20bas speakers to the behringer outputs - all balanced.

voila

ah.. and if my old electric system plays tricks on me I may get a couple of those nice outlets / power regulators.

ps: I got rid of a lot of my hum by plugging my computer screen to the same outlet as my computer tower (thanks for the tips)

[ This Message was edited by: mano1.com on 2002-05-10 21:52 ]

Round1 · Post by **Round1** » Sun May 12, 2002 4:12 am

Yeah, glad you checked the output jacks on your A16, you'll have noticed that the manual clearly states that you use a stereo jack with no sleeve connected when you are going to an unbalanced destination. You can actually damage the A16 if you don't do this! (Of course this isn't a problem when using the inputs on the A16, it'll recognise the difference between a mono or stereo plug)

I've also gotta add one more thing........I've now had my A16 for a coupla months now, and in a nutshell, it fuckin' rocks, it's very quiet, and sounds very nice as a AD (x16) convertor. (I'm comparing the sound with that of my Tascam DA30mkII Dat, which is 16 bit of course)

Round1 · Post by **Round1** » Sun May 12, 2002 4:15 am

Whoops......in the above post it should read that you use a stereo plug with no connection on the "RING'"....(not the sleeve!)