Hum from BB VRBox

[shaggy]

I am getting humming (not really but some sort of noise that resembles a hum) from my SBM when I run it off of a BB VRbox.  I am also running a Sonosax as well.  Marc wired up a jack that has 5V and 18V from the same XLR out, the other XLR out has 6V for my SBM.  In either case, whether I run it from the 5V or 6V jack, I get hum.  Also the hum is only present when the Sax is in place running of the 18V source and the mini>RCA connection is made with the Sax>SBM.  There is no hum when I run the SBM off of a wall wart so the issue seems to be related to the VRbox and not the DC to DC converter in the SBM.  I take the Sax out and run it off of 9Vs, no hum.  Again, the two are link via a mini>RCA and when that is taken out, no hum.  The BB VRbox runs from 2 X 9V wallmarts in a series, for a total of 18V.

Any suggestions.  I asked Marc and we are in the process of troubleshooting it.  I figured I could pick all the TS.com'er brains about it.

ANDY

[leegeddy]

I am getting humming (not really but some sort of noise that resembles a hum) from my SBM when I run it off of a BB VRbox.  I am also running a Sonosax as well.  Marc wired up a jack that has 5V and 18V from the same XLR out, the other XLR out has 6V for my SBM.  In either case, whether I run it from the 5V or 6V jack, I get hum.  Also the hum is only present when the Sax is in place running of the 18V source and the mini>RCA connection is made with the Sax>SBM.  There is no hum when I run the SBM off of a wall wart so the issue seems to be related to the VRbox and not the DC to DC converter in the SBM.  I take the Sax out and run it off of 9Vs, no hum.  Again, the two are link via a mini>RCA and when that is taken out, no hum.  The BB VRbox runs from 2 X 9V wallmarts in a series, for a total of 18V.

Any suggestions.  I asked Marc and we are in the process of troubleshooting it.  I figured I could pick all the TS.com'er brains about it.

ANDY

andy;

i highly doubt that a dc supply will cause the "hum". it could be a combination of many things, or perhaps your Sax's mini plug.

please feel free to send the box/cables back for a full refund.

marc

[twatts]

Could it be your Sax>SBM cable is unshielded/unbalanced/un-whatever, and it is picking up RF from the VR???  Maybe its like when you run your cables across a high power source you get noise.  I notice hum when I run a fan in my room - my stereo is close to the window and one of my cables runs directly underneath when the fan sits in the window...

Interesting, but I really ahve no clue...

Terry

[Brian]

Could it be your Sax>SBM cable is unshielded/unbalanced/un-whatever, and it is picking up RF from the VR??? Maybe its like when you run your cables across a high power source you get noise. I notice hum when I run a fan in my room - my stereo is close to the window and one of my cables runs directly underneath when the fan sits in the window...

Interesting, but I really ahve no clue...

Terry

i think you might be on to something.  noise can definitely be introduced when a badly shielded cable touches a cable coming from a large power source.  i'm not sure if this is the case for DC over a cable but i'm positive for AC.

[dnsacks]

couldn't the problem also come from failure to electrically isolate the sax from the sbm-1, i.e. a ground loop-type situation.  Should be easy to check, if disconnecting either the sbm-1 or the sax from the external battery causes the noise to go away, it would seem that the combination of the 2 being connected to the same power source simultaneously is the source of the problem.

Would/could adding diodes to one of the power lines fix this?

[shaggy]

i am thinking some sort of ground loop feedback.  again, the connection between the SBM and sax needs to be made in order to hear the sound.  marc had suggested the mini plug might be the culprit on this one, I assume loose grounding.  it does not matter where the VR box is located, it does not alter the intensity of the sound.  I changed the mini>RCA cable too, I still get it.  if any of the items run on batt power the problem goes away. 

[silentmark]

I also am having the same problem trying to run the MT and the Sonosax off of 2 walmart batts through the Juice Box from ToddR. Both run fine seperately, but put them together and it produces some nasty interference ... Has anything been resolved yet ?

[F.O.Bean]

sax takes 18v isd that what andy said above

if so, maybe because its sucking so much jucie and needs so much juice, that one of the devices is taking away 'juice/power' from the oither

[shaggy]

Yep, what I suspected...those Wallmarts in a series act real funny.  I cannot get it to power even my JB3 reliably!  So, the VRbox has gone unused since the hum announced itself.  I solved the Sonosax powering with a hack solution at the last minute b4 I ran off to Asagiri:

http://taperssection.com/index.php?topic=51489.0

It is still running....got another hour off of it taping my brazilian friend, Gullerime, play his accordion.

[silentmark]

sax takes 18v isd that what andy said above

if so, maybe because its sucking so much jucie and needs so much juice, that one of the devices is taking away 'juice/power' from the oither

I don't know if that is the case as you can run the sax down to about 12v. I have a 12v sla that works fine but just makes the power light blink every second or so. You get power for a good 10 plus hours. I never reached it max, but I was told about 15-16. The only thing it supposedly makes the sax more "sensitive" the lower the voltage it is run at.

I can run the sax off both walmarts through the JB or just the MT, but not both (sax&MT) at the same time. Still makes me think it's the sax design somehow and not two walmarts in series. Carrying a 12v sla (sax), 2-6v (sbm & DAT) and now 1 or 2 walmarts (MT) is a PITA. I know I will prolly ditch a 6v for my DAT at some point once I am comfortable and confident of the MT, but for now I can't. I know I will be getting a V3 or minime for 24bit in the future, but will prolly still run the sax in front as I dig the sax sound alot. My power sources weigh more than the rest of my rig, lol, sheesh ...

[Kyle]

sax takes 18v isd that what andy said above

if so, maybe because its sucking so much jucie and needs so much juice, that one of the devices is taking away 'juice/power' from the oither

I don't know if that is the case as you can run the sax down to about 12v. I have a 12v sla that works fine but just makes the power light blink every second or so. You get power for a good 10 plus hours. I never reached it max, but I was told about 15-16. The only thing it supposedly makes the sax more "sensitive" the lower the voltage it is run at.

I can run the sax off both walmarts through the JB or just the MT, but not both (sax&MT) at the same time. Still makes me think it's the sax design somehow and not two walmarts in series. Carrying a 12v sla (sax), 2-6v (sbm & DAT) and now 1 or 2 walmarts (MT) is a PITA. I know I will prolly ditch a 6v for my DAT at some point once I am comfortable and confident of the MT, but for now I can't. I know I will be getting a V3 or minime for 24bit in the future, but will prolly still run the sax in front as I dig the sax sound alot. My power sources weigh more than the rest of my rig, lol, sheesh ...

FWIW, you can run the d7/sbm1 off of one 6v sla for 10+ hrs. I used to run that and I think I still have the xlr>2 adapta-plugs cable around here somewhere. I never measued the run time but at Big Cypress on 12/31/99 I powered up at 11:30pm and made it all the way through with lots of juice to spare...

[silentmark]

FWIW, you can run the d7/sbm1 off of one 6v sla for 10+ hrs. I used to run that and I think I still have the xlr>2 adapta-plugs cable around here somewhere. I never measued the run time but at Big Cypress on 12/31/99 I powered up at 11:30pm and made it all the way through with lots of juice to spare...

Yeah I used to do that until I ran out of juice a few times and since it has been a habit to use 2 batts seperately, shrug. It's the 12v I was looking to get away from. I could go back to running 9v lithiums, but they can be pricey. Didn't like the recharable 9v at all. Just kinda bummed that this  sax setup gets the 'hum' ...

[Kyle]

FWIW, you can run the d7/sbm1 off of one 6v sla for 10+ hrs. I used to run that and I think I still have the xlr>2 adapta-plugs cable around here somewhere. I never measued the run time but at Big Cypress on 12/31/99 I powered up at 11:30pm and made it all the way through with lots of juice to spare...

Yeah I used to do that until I ran out of juice a few times and since it has been a habit to use 2 batts seperately, shrug. It's the 12v I was looking to get away from. I could go back to running 9v lithiums, but they can be pricey. Didn't like the recharable 9v at all. Just kinda bummed that this  sax setup gets the 'hum' ...

I never had that combo run out on me, but B.C. was the longest thing I recorded w/o recharging.

I am sick of the 12v as well, carry it around for the ad2k, too heavy but sounds sooo good.....
What did you not like about the 9v. I just purchased one for my psp-2 but did not get it yet

[mmedley.]

I could go back to running 9v lithiums, but they can be pricey. Didn't like the recharable 9v at all. Just kinda bummed that this  sax setup gets the 'hum' ...

I ran the Sax with alkaline 9V's. I used lithiums once or twice and only managed to get about 2-3 hours more. The Energizer alkalines ran the Schoeps for about 5 - 5 1/2 hours which covered me more than plenty for the openers and main acts.

Lowe's has some of the best prices for 9V's. I think I paid $7 for a 4-pack of Energizer 9V's last time I bought them.

[Todd R]

Mark,

If you've got the right connectors, you might try your 12v in to the JBox rather than the pair of Walmart Li-ion in series and see if you have the same problems.   That way you can see if the issue is with the Li-ion batteries or with the combo of the JBox and Sonosax.  If it does turn out to be some oddity with Li-ion batteries in series, you could ditch those and get a pair of NiMH RC battery packs.

At any rate, as I said, feel free to send the JBox back for a full refund.

-Todd