Topic: VMS-5U, KCY, & phantom power

[jadedphan]

Hey now,

So i ran my newly purchased rig additions @ phish's merriweather gigs this weekend.  On the first night, to my disgust, I realized during the middle of "Daniel Saw the Stone" (first song of the first set of the first night) that I had neglected to engage my phantom power switch.  I was running Schoeps MK41 > KCY > Schoeps VMS 5-U > Mytek 192 > Tascam HD-P2 @ 96/24.  What threw me was that, visually, my levels looked as expected during "daniel."  As soon as the tune ended, I threw the phantom power switch on.  On previous incarnations of my rig (ad1000, mini-mp > hd-p2, V2 > ADC, V2 > Ad1000), if you flipped the phantom on or off during recording, you ALWAYS got a digital pop.  Also, while you would get some signal to pass, and some levels, the sound was always hollow and crappy, and the levels were totally anemic.

To my surprise, when I auditioned the recording later that night, "Daniel" sounds as though phantom was on, and both levels & sound quality are stellar.  At the point where I flipped the phantom switch (I had notated the time during the gig), there are NO sound anomalies, pops, or glitches at all.

My question is this,
does the VMS/KCY combo AUTOMATICALLY engage and run phantom power?  Should I therefore NOT engage the switch for any reason?  Does the switch have any function at all with this combo?

I don't want to trash any recordings, but also don't want to eat up any more battery than needed (I wasn't sure how the phantom on/off would affect battery draw), and also wasn't sure if having the phantom on would OVER POWER the caps by any chance.

Any knowledgeable help would be GREATLY appreciated.  Either way, it sure was a nice safety net to have at the time!

thanks for the help,
-bry

[Brian Skalinder]

I've not checked the manual to confirm, but I would guess the phantom power switch only applies to the XLR inputs.  So when switched to KCY mode, it provides the appropriate power to the caps, and phantom power isn't involved.

[jadedphan]

I've not checked the manual to confirm, but I would guess the phantom power switch only applies to the XLR inputs.  So when switched to KCY mode, it provides the appropriate power to the caps, and phantom power isn't involved.

This would seem to make sense....obviously I was getting phantom from somewhere... I just want to make sure that the phantom power switch doesn't need to be DISENGAGED when running KCY's for optimal unit life, or whatnot.

I don't have a manual.  I believe one was sent to me when I bought the unit (used), but for some reason it no longer resides with me.

Thanks much,
-Bry

[Brian Skalinder]

I don't have a manual.  I believe one was sent to me when I bought the unit (used), but for some reason it no longer resides with me.

http://www.schoeps.de/en/products/vms5/downloads

[H₂O]

Phantom power is XLR only and is not applicable to KCY connector

[todd e]

I've not checked the manual to confirm, but I would guess the phantom power switch only applies to the XLR inputs.  So when switched to KCY mode, it provides the appropriate power to the caps, and phantom power isn't involved.

QFT

[StuStu]

Phantom power is XLR only and is not applicable to KCY connector

[DSatz]

Schoeps "Colette" cables don't use 48-Volt phantom powering--they carry one DC voltage (relatively low) for biasing the FET in the capsule end of the cable, and another DC voltage (normally around +60) to polarize the capsule. If you're using Schoeps CMC-series amplifiers, those two voltages are produced inside the amplifier from the phantom powering that you provide the amplifiers. But the VMS preamps have their own DC converters and regulators built in, so if you're using the KCY (stereo "Colette" cable) arrangement, phantom powering is entirely superfluous.

(Or, what most of the other people in this thread have already said.)

--best regards

[Big Perm]

Schoeps "Colette" cables don't use 48-Volt phantom powering--they carry one DC voltage (relatively low) for biasing the FET in the capsule end of the cable, and another DC voltage (normally around +60) to polarize the capsule. If you're using Schoeps CMC-series amplifiers, those two voltages are produced inside the amplifier from the phantom powering that you provide the amplifiers. But the VMS preamps have their own DC converters and regulators built in, so if you're using the KCY (stereo "Colette" cable) arrangement, phantom powering is entirely superfluous.

(Or, what most of the other people in this thread have already said.)

--best regards

Yeah, but yours sounds way better 

[F.O.Bean]

Phantom power is XLR only and is not applicable to KCY connector

BUT, since hes running KCY>VMS, doesnt he need the phantom ON for the KCY. So if Phantom applies to XLR ONLY, how would someone use the VMS with a KCY, if the KCY doesnt provide any phantom powering

[page]

Phantom power is XLR only and is not applicable to KCY connector

BUT, since hes running KCY>VMS, doesnt he need the phantom ON for the KCY. So if Phantom applies to XLR ONLY, how would someone use the VMS with a KCY, if the KCY doesnt provide any phantom powering

Phantom powering applies to the mic bodies which convert it into standard power and polarization power. The KCY is assuming you are already supplying the later and don't need the former.

[F.O.Bean]

Phantom power is XLR only and is not applicable to KCY connector

BUT, since hes running KCY>VMS, doesnt he need the phantom ON for the KCY. So if Phantom applies to XLR ONLY, how would someone use the VMS with a KCY, if the KCY doesnt provide any phantom powering

Phantom powering applies to the mic bodies which convert it into standard power and polarization power. The KCY is assuming you are already supplying the later and don't need the former.

Ahh, OK, thanks Page

[F.O.Bean]

I LOVE my brand new KCY cable Its SOOOO NICE having just one cable snake down the stand And the Schoeps cabling is of very high quality Its a lil thick and def rugged/durable!

[F.O.Bean]

And I got 10 hrs running [2] generic 9v's That makes festy season alot better. I thought I would only get around 4-5 hrs with internals on the Lemosax. Maybe because its just a lemosax version, thats why it gets so much longer runtimes

[DSatz]

The "Lemosax" uses a DC converter that steps up the battery voltage directly to the polarization voltage for the capsules (ideally ca. 60 Volts, though I don't know what actual value is used). The current drawn for polarization is next to nothing, so that can be done quite efficiently. The operating voltage for the FETs in the cable demands somewhat more current, but can be derived very simply from the preamp's own DC supply.

By comparison, when you connect a pair of Schoeps 48-Volt microphone bodies, the preamp has to convert its internal supply voltage to 48 Volts DC at about 9 mA total (~430 mW), which is much more of a drain on the batteries.

--best regards

[page]

The "Lemosax" uses a DC converter that steps up the battery voltage directly to the ~60 Volt polarization voltage that the capsules require; the current draw is next to nothing, so that can be done quite efficiently. The operating voltage for the FETs in the cable demands somewhat more current, but the voltage doesn't require any step-up; it can be derived very simply from the preamp's own DC supply.

I thought the lemosax ran at 48v for polarization voltage and you just lose like 2db of sensitivity in trade?

[DSatz]

Someone wrote me a private message asking about that, whereupon I went back and re-edited my posting. I had simply assumed the nominal voltage; sorry for any confusion this may have caused.

A modest proposal: Perhaps Mr. Blanc at Sonosax could be asked what voltage his preamp actually puts out. 48 Volts, if that's what it is, would only make the capsules ~1.9 dB less sensitive than the nominal voltage. The exact voltage has no other effect on sound quality as long as it stays constant. And 1.9 dB lower sensitivity wouldn't make an audible difference very often if ever, since the noise floor is so low already. I wouldn't assume that it would necessarily be preferable to have the "Lemosax" provide 60 Volts rather than 48, not knowing the overload point of the preamp's input circuit. One has to look at these things as systems, and not just take one parameter out of context.

For many years Schoeps, Neumann and AKG made 48-Volt phantom-powered microphones with capsules that had originally been designed for 60-Volt polarization, but which were polarized in those models by the incoming 48 Volts without a DC converter, mainly for the sake of a low-current design. This includes the Schoeps CMT 50 series, the AKG C 414 EB-P 48 and almost the entire Neumann fet 80 series including the U 87 and KM 84. Those are still considered to be very good microphones today, so evidently that wasn't such a scandalous thing to do, engineering-wise.

--best regards

[F.O.Bean]

Thanks for the info guys!

[hi and lo]

Since there was a bit of hesitation on this thread a few months ago, I managed to find a post from ts.com that confirms the polarization voltage of the Lemosax is 48v. Original post here:

From Sonosax:

Dear Mr xxxx,

The SX-M2/LS which is no longer available is replaced by the  SX-M2/LS2.

The SX-M2 LS/2 provides with both a 5 pin Binder connector for the Schoeps KCY active cable and two 3 pin Lemo's.
The SX-M2/LS2 supply 48V for the Schoeps capsule.
The voltage difference between the 60V and the 48V is not an issue.
The 12V difference are almost negligible as it affect the max acoustic SPL ( Sound Pressure Level ) accepted at the capsule by only a couples of dB.

I hope this will answer your questions.
Kind regards

Pierre Blanc
SONOSAX
Sales and Customer Support