New MC012 Problem

[ja_]

So i ended up getting a rolls phatom power box the other day to fix my first problem (see: oktava mc012 help! thread) i would have just gotten a preamp or a better mixer but i'm really strapped for cash right now.

so now i can record and everything is fine and good, i really like the mic but.... i'm picking up a radio station when i record!!! this has happened to me with really cheap radio shack cables but now i'm using all high(er) quality stuff. every cable i have but the main mic cord is Hosa.

heres the set up:
mic to generic guitar center mic cables (3 20foot cables linked, i need that length) to rolls phantom power box, to hosa xlr to 1/4 to the mic on on a dj mixer (stanton), to hosa RCA to 1/8th to my soundcard. soundcard is the crappy one that came with my pc, but does not pick up radio stations when i record straight from vinyl.

where do you guys think the problem is occuring???? its driving me nuts over here

 

[Herm]

Try and get rid of 1 or two of the mic cables and see what happens just for a test you
should be able to do that for a few minutes and see if its the mic cable.
Also a cable can act like an antena and cause problems just cause it is a multiple of
a certain radio frequncy and a foot in length either way could cause a problem.
Or maybe invest in 1 piece of descent cable and get rid of all the connectors, take
two connectors off of 1 of the others and make 1 long cable.
Beg borrow or steal another 1/8th inch cable and try that.
you might try placing your phantom box at a differant place in the cable run and see what
happens there or maybe try shielding the rolls with some foil around it and see what happens.
I dont know when it comes to rf noise it could be any where just some thoughts on things to try.

 

[skippy]

I'll bet a beer that the RF crud is riding in on the AC power, through the wall wart, and into your phantom power box. Regrettably, that item is generally regarded as very iffy: you're actually the first person I've heard of who has one that actually *works*. I've posted about the experiences a buddy of mine had with that piece elsewhere on the site, the link to that is below.

I congratulate you on getting one that works- but it is an excellent place for EMI to sneak in. You'll need the power to that box to be as clean as possible. If you can get a very good line noise filter, that'll help. However, the first thing I'd do would be to try making a quick little adapter to allow you to power the box from a 9v battery- you can get the clip and the power plug at Radio Shcak. Byt battery powering your phantom box, you can positively determine whether or not the RF is coming in via the wall wart.

If you do this, MAKE SURE that you wire the battery connector with the right polarity. Consult the schematic in the phantom box's manual (a link to it is below, if you don't have the hardcopy). Reversing the polarity will melt that monster down instantly- that's one of it's worst behaviors...

Frankly, though, for a true budget setup- I'd ditch the PB23, which really is a marginal design, and snag something like the Behinger MX602 mixer. Those have a real phantom supply, two perfectly usable mic pres, and a decent enough mix buss. It doesn't have the RIAA preamp for the turntable that your DJ mixer has, but you may find it much more flexible and usable to drive your soundcard for non-vinyl-based work. For sure, it'll power your mic better. And they are nearly free these days- they can be had for $60 or less. Your mileage may vary...

https://homerecording.com/bbs/showthread.php?s=&threadid=39895&highlight=rolls+phantom

http://www.rolls.com/new/pb23.html

 

[ja_]

damn! it looks like i just might have to go with the behringer, even though i hate to spend more friggin money. it WOULD improve my overall sound though wouldnt it? theres a little bit of hiss i'd like to get rid of as well.

do you know where i can find one for 60 or under? the cheapest i see is 80 online, i may not be looking hard enough though

 

[h kuhn]

However, the first thing I'd do would be to try making a quick little adapter to allow you to power the box from a 9v battery- you can get the clip and the power plug at Radio Shcak.
https://homerecording.com/bbs/showthread.php?s=&threadid=39895&highlight=rolls+phantom

http://www.rolls.com/new/pb23.html

He'll need 2 9v batteries in series, the box requieres 14-18 vdc.

And ja_ now you learned something the hard way: buy cheap, buy twice. No pun intended, i have made this very same expierience quite a few times (can somebody say "studiomaster"?). My solution was to marry a wife with a good job....

go for the behringer, but be prepared that you'll want to upgrade soon. if you want something to stay with for longer, buy the mackie 1202vlz pro, you might find a used one somewhere (you will buy one sooner or later anyway). behringer uses very cheap pots and faders, they might get scratchy quite soon. Their power supplies are also a bit underdimensioned.
YMMV
BTW: the hiss you are talking about, does it goe away when you press your mouse button?
Harald

 

[ja_]

nope, the hiss is there button or no button. i notice it seems much more prominent once i start recording though, but i could just be paranoid.

with 1 cable i get some RF but its low volume, with all three cables i get it signifigantly louder, to the point where its a huge problem in my recording. would a behringer knock the whole RF problem out altogether? i DID find one locally today for 60 bucks in real nice condition.

good lookin out on all this guys, you've taught me more in a week than i would have learned in months via the hard way. not to mentioned saved money.

 

[h kuhn]

nope, the hiss is there button or no button. i notice it seems much more prominent once i start recording though, but i could just be paranoid.

with 1 cable i get some RF but its low volume, with all three cables i get it signifigantly louder, to the point where its a huge problem in my recording. would a behringer knock the whole RF problem out altogether? i DID find one locally today for 60 bucks in real nice condition.

good lookin out on all this guys, you've taught me more in a week than i would have learned in months via the hard way. not to mentioned saved money.

Ja_
I am absolutely not sure if that could be a solution for your RF problem (it's one of the very few problems i haven't run into yet...) but you might give this a try: if you own a soldering iron you might try to solder some quality mic cable, buy some switchcraft conectors (3-5 $ each, they hold a lifetime) and the best quality of cable (22gauge low capacitance, the hot and cold wire should be twisted) you can find, normaly about 70cent/m. Download one of the manuals for the mackie mixers, there is all the info about the wiring. Also keep the cable run from the rolls to the mixer and from there to the soundcard as short as possible, this is the unbalanced part of your signal path and therefore prone to pick up the RFs.

keep swinging
Harald

 

[Randy Yell]

Ja,you could also check out the M-Audio Audio Buddy for not much more than the Behringer.

 

[ja_]

so i did a little bit of trouble shooting today and heres what i've found out...

i plugged my mixer out to stereo in and just recorded to tape this time. the recording level was very low, so i turned up the mic and master levels on the dj mixer. i did NOT get the RF noise but i DID get a really loud fairly high piched hiss, which is almost just as bad. not to mention going to regular casette tape, the recording quality sounded like crap.

so, does this sound like a case of dirty phantom power from the rolls box or what?? as inexperienced as i am, thats what i'm leaning towards now from my own experiments.

now, part 2.

when i first plug in the 1/8 jack into my sound card (from mixer out) to record, i get a LOUD radio station, and when i leave it half way in half way out i get the RF constantly. but once its in, it goes away. (until i record with the mic). recording a drum machine or from vinyl throught he same dj mixer with the same computer connection i do NOT get this RF noise in the recording.

so whats it sound like guys? my mixer rca out to 1/8 on the soundcard is a hosa cable, and those havent failed me yet. but is there any new light to be shed on this subject? i'm thinking real good thoughts about taking the rolls back to pick up that behringer tomorrow. but will this cure my RF problems, or is there an issue with the soundcard in and that particular cable??

major thanks here guys, i feel like theres only one or two peices missing from the puzzle at this point. at least i certainly hope so.

 

[ja_]

bump

 

[h kuhn]

now, part 2.

when i first plug in the 1/8 jack into my sound card (from mixer out) to record, i get a LOUD radio station, and when i leave it half way in half way out i get the RF constantly. but once its in, it goes away. (until i record with the mic). recording a drum machine or from vinyl throught he same dj mixer with the same computer connection i do NOT get this RF noise in the recording.

i don't understand. does this mean you get RFI when you have only the mixer connected to your soundcard or not?

look what i found:
"A one-end-only shield connection increases the possibility of high frequency (radio) interference since the shield may act as an antenna. Many reduce this potential RF interference by providing an RF path through a small capacitor (0.1 or 0.01 microfarad ceramic disc) connected from the lifted end of the shield to the chassis. The fact that many modern day installers still follow this one-end-only rule with consistent success indicates this and other acceptable solutions to RF issues exist, though the increasing use of digital and wireless technology greatly increases the possibility of future RF problems."

could be the cable from your phantom box to the mixer. To learn more about the item read here:
http://www.rane.com/note110.html

 

[ja_]

when i have the mixer out connected to my soundcard and have the mic mute off on my soundcards volume controls, THEN i get the rf stuff. but i also get that high pitched noise when i use my stereo, so i guess thats rf too?

what would you do at this point kuhn? you think canning the phantom power box and grabbing that behringer is going to help me out at this point?

 

[h kuhn]

when i have the mixer out connected to my soundcard and have the mic mute off on my soundcards volume controls, THEN i get the rf stuff. but i also get that high pitched noise when i use my stereo, so i guess thats rf too?

what would you do at this point kuhn? you think canning the phantom power box and grabbing that behringer is going to help me out at this point?

my amateurish guess is that the RFI is not caused by the phantom box, but the unbalanced connection from the rolls to your mixer (the shielding acts like a long antenna). As you could eliminate at least one part of the unbalanced line by using the behringer and would get some better preamps, too, i would go for the behringer (and return the rolls). *BUT* you might still get RFI, as long as you have unbalanced conections you can always run into trouble.

 

[ja_]

ouch.

can you tell me how i could avoid the unbalanced connections?

i think what im going to do tonight or tomorrow morning is take all this crap in to guitar center and trouble shoot it on their equipment, and see what we can come up with.

 

[h kuhn]

ouch.

can you tell me how i could avoid the unbalanced connections?

i think what im going to do tonight or tomorrow morning is take all this crap in to guitar center and trouble shoot it on their equipment, and see what we can come up with.

did you read the rane document? There is all you need to know about balanced/unbalancd connections, on www.fmraudio.com you can also find a nice article. And I am shure that there are quite a few articles here on that forum dealing with the pitfalls of unbalanced connections. The point is not that i don't want to help you, but that the above mentioned articles explain it much better than i could do (i am not a native speaker)

BTW the hiss you hear probably comes from the mic pre on your soundcard. There is a reason why pro quality pres cost hundreds of dollars, and not 50cents like the chip on these soundcards.

 

[ja_]

damn. it sounds like none of my cable over here is balenced. i notice with every extra length i plug in the hum/RF is louder.

well thanks for all your help, i'm going to take the whole heap of stuff into guitar center tomorrow and let those bastards in pro audio take a crack at trying to ease some of the pain. i'm not good with cables and soldering and that kind of thing at all, otherwise i'd just get everything straightened out myself.

here is something i whipped up the first time i got everything working moderately well, i put a lot of fx on the drum track to get rid of (or at least take down a few notches) the RF noise.

http://www.ampcast.com/LST-50114-mus-128-1597939-0-0-0/some_rashied_ali_g13_shit.m3u

 

[h kuhn]

damn. it sounds like none of my cable over here is balenced. i notice with every extra length i plug in the hum/RF is louder.

http://www.ampcast.com/LST-50114-mus-128-1597939-0-0-0/some_rashied_ali_g13_shit.m3u

the hum i hear on the recording sounds like a ground loop to me, it sounds like static noises emited from a harddisk or the fan. I had the very same problem with my dsp2000, i ditched it and dropped down much more cash than i wanted to buy a Layla24, now i can connect even unbalanced gear (the mpx100 and my rnc) without any trouble, everything is dead quiet. Thats the big problem, recording cards with balanced conections are damn expensive. One soulution could be a cheap card with spdif i/o and a converter box like the flying cow. From the mic to the converter you will have a fully balanced connection and then you are in the digital domain.
Did you connect everything to one contact. ie does the power for all the units in your recording chain come from one single power outlet? If not try this and check if the noise diminishes.

 

[Havoc]

Some other silly things you might check:
- is your soundcard making good contact with your pc chassis? This may sound strange, but the filtering of the inputs of the soundcard may rely on it to do a good job.
- try a ferrite clamp around the cable. Try the in-out of every cable in your setup, also power supply leads.
- if you are good at soldering, put a small capacitor (100p-1n) from the input of your card to ground. The easiest way is making a small cord and solder them to the plug going into the card.

As for finding the source, take it step by step. Nothing plugged in, only a cable plugged in, with a cable to the phantom (not powered), with phantom powered, with cable in phantom, with mic.... and see where it starts.

 

[ja_]

i think i've found the culprit cable, it seems to be my mixer out to soundcard in. the guys at guitar center told me to monster cable everything and then i'd be fine but damn, thats gonna break my wallet in half (especially since i need a SIXTY foot length!)

i'm sort of reluctant to make a move one way or the other now, since my soundcard is crappy. i have a buddy with a soundblaster platnium and the 1/4 line in on it works just fine for him (he uses a rolls pb box too), no RF.

it would be cheaper all the way aroudn to just scrap all this and go with a MD recorder and one of those sony stereo mics. at least there wouldnt be any RF that way. thats an alternative that sounds pretty good to me right about now.

at some point i'd like to get a mbox or digi001(or002, by the time i have the cash) pro tools system anyway. and i KNOW those things are going to be balenced.

i'll check into that spdif thing thiugh kuhn, thanks.

 

[h kuhn]

at some point i'd like to get a mbox or digi001(or002, by the time i have the cash) pro tools system anyway. and i KNOW those things are going to be balenced.

i'll check into that spdif thing thiugh kuhn, thanks.

AFAIK only i/o 1 to 4 is balanced on the digi 001. Protools -the only software with a 19" dongle...

look into rme audio stuff, especially the multiface. i think the low end digi hardware can't hold a candle against this.