Phantom power interference....

R

Rhymemaker

New member
Newbie and first post so be nice!

I have a problem with a high pitched interference when on phantom power.

I have a Tascam US 600 and a selection of new and second hand mics. My aim is to record stage shows, so to that end I own three Stageline Em925p's rifle/shotgun mics. These can be either phantom or battery powered. I also inherited a Philips LBB 9510/20 which looks like a dynamic mic but is a condenser so needs phantom.

The issue I have is that the stageline's have a faint but audible whine when connected and phantom powered (on battery there's no whine). Made me think a problem with phantom from the unit. However, connecting the Philips there's no whine when on phantom.

Whilst I can run on battery to solve the problem (rather use phantom though) I'm eager to learn if this just a case of budget mics or is there something else going on that I could solve.

Have tried to eliminate poss sources such as -

- tascam unit connected/not connected to PC - no change
- all PC's/gadets unplugged from power supplies throughout the house - no change
- Mobile phones switched off etc - no change
- Different xlr leads - no change
- I have no fluorescent lights in the house

Any theories......?


Many thanks


Gary
 
I think you need to try those mics with phantom power from some other source besides the TASCAM unit...if no noise, it's the TASCAM unit, if they still have noise, it's the mics.
 
I had kind of ruled out the TASCAM as the Philips was a clean feed, but then again the chances of all three mics having a problem points to the TASCAM doesn't it. I'll get them tested on another desk as you suggest and post back. TY for the reply.

Getting the feeling sometimes Logic doesn't apply to these things. Am I right?
 
same phantom power issue with US-600

Hi Gary,

It's been a long time since your post here about the Tascam US-600 phantom power issue, but I'm having the same problem. I've recently received a brand new factory sealed US-600 unit and thought I would make some use of it. I experienced the exact same problem that you did with condenser mics and phantom power. I've ruled out all factors and I think it must be the US-600 that is faulty. Also, it turns out that it only produces the issue when 2 or more condenser mics are connected that require phantom power. I was wondering if you still remember whether or not you were able to find a solution to this and what it might be.

Many thanks,

Andras


Rhymemaker said:
Newbie and first post so be nice!

I have a problem with a high pitched interference when on phantom power.

I have a Tascam US 600 and a selection of new and second hand mics. My aim is to record stage shows, so to that end I own three Stageline Em925p's rifle/shotgun mics. These can be either phantom or battery powered. I also inherited a Philips LBB 9510/20 which looks like a dynamic mic but is a condenser so needs phantom.

The issue I have is that the stageline's have a faint but audible whine when connected and phantom powered (on battery there's no whine). Made me think a problem with phantom from the unit. However, connecting the Philips there's no whine when on phantom.

Whilst I can run on battery to solve the problem (rather use phantom though) I'm eager to learn if this just a case of budget mics or is there something else going on that I could solve.

Have tried to eliminate poss sources such as -

- tascam unit connected/not connected to PC - no change
- all PC's/gadets unplugged from power supplies throughout the house - no change
- Mobile phones switched off etc - no change
- Different xlr leads - no change
- I have no fluorescent lights in the house

Any theories......?


Many thanks


Gary
Click to expand...
 
Thought the US-600 was discontinued years ago. I remember buying a bunch at discount and selling to members here at cost...

Anyway, I don't recall hearing issues with phantom power but then I didn't own one myself. I then had the US-1641 that didn't have that issue.

I wonder what the specs are for that unit and if phantom power is enough for multiple condensers.

Suggesting this guy to investigate. [MENTION=89697]ecc83[/MENTION]
 
jimmys69 said:
Thought the US-600 was discontinued years ago. I remember buying a bunch at discount and selling to members here at cost...

Anyway, I don't recall hearing issues with phantom power but then I didn't own one myself. I then had the US-1641 that didn't have that issue.

I wonder what the specs are for that unit and if phantom power is enough for multiple condensers.

Suggesting this guy to investigate. [MENTION=89697]ecc83[/MENTION]
Click to expand...

Wait, I thought you had the US-1800s that you sold off at cost. I believe I got mine from you which I then traded to Rami for his US-600.

I don't recall ever hearing any whine from mine. I've had, at most, two condensor mics; Shure KSM-137s. I might have to pull it out and try it again to see if it whines with LDCs.
 
Chili said:
Wait, I thought you had the US-1800s that you sold off at cost. I believe I got mine from you which I then traded to Rami for his US-600.

I don't recall ever hearing any whine from mine. I've had, at most, two condensor mics; Shure KSM-137s. I might have to pull it out and try it again to see if it whines with LDCs.
Click to expand...

I had the US1641. Then upgraded to the US1800. When I upgraded again to Steinberg UR824's, I sold you my 1800. I think. lol It been a while.

Definitely RAMI bought one of the 5 US-600's I got for $100. Can't remember who bought the others...
 
US-600? How old was that model?

Jimmy - I got my US-800 from you, it has no issues with 2 condensor mics at one time (never tried more than that).
 
ECC83 here as requested!

Sounds to me that the US 600 uses a fairly crude 'diode pump' &chip circuit to produce 48 volts. The fact that the whine only shows on full load is a clue, such circuits drop in frequency as the load increases (well, mark-space ratio changes to be pedantic but we HEAR a drop in pitch) . It seems this noise is not being properly filtered before it hits the mic inputs. Trouble is, the mic line has to carry audio as well as DC so you can't just slap bloody great capacitors around!

You can buy phantom power units for under £20 which should solve the issue but beware. I bought a couple that sported 48V and 12V switched outputs. They were crap and could not deliver more than about 2mA of current. A second unit with two channels but just 48V was fine.

Dave.
 
You must log in or register to reply here.
Back
Top