Phantom Power for Oktava MK-219 Mic

Masten

New member
Hi

I practise my live set at home using an old Octavia MK-219 Mic, into a TC-Helicon Mic Mechanic (v1) into a Steinberg u22 into powered monitors

The Octavia MK-219 hisses a lot though as it needs 48V Phantom Power and the Mic Mechanic only produces 24V

What would be the best cheap and easy solution to this? Would putting something like this:

SubZero Phantom Power Supply at Gear4music
Behringer PS400 Phantom Power Supply at Gear4music

between the Mic Mechanic and the Octavia sort it out?

The Mic Mechanic has always on phantom power so would that cause any problems going into one of these units?

Thanks very much in advance

Masten :)
 
do you mean a Steinburg UR22? I couldn't find a u22. It has 48v phantom power, you don't even need to use the mic mechanic
 
Hi there

Yeah sorry is a ur22.

I'm using the Mic mechanic pedal for the reverb. I use this inline with the mic at small gigs (where phantom power not a problem as they use dynamics) and want to simulate as much as possible that environment when Im practising at home. I only have a condenser mic at home though that needs 48v.

Unless you're saying that the phantom power on the ur22 (which I have off when mic mechanic is inline) would go through the mic mechanic to the mic, but am worried it might damage the mic as that would be 48V from that and 24V from the Mic mechanic

Any phantom power experts out there?

Thanks

M
 
I've got a Behringer PS400. I believe there are a couple of capacitors which would block any phantom voltage coming from the Mike Mechanic from getting into the 48 volt side of the PS400 and the mic. Conversely these same capacitors prevent the PS400 48vdc from getting to the Mic Mechanic. I'm 95% sure you wouldn't have a problem. Connect everything up and then apply power.

However........ if it were me doing this......
The PS400 goes about $24-$25. Rather than use the money for something you'll likely never use on anything else except this setup, get an inexpensive dynamic mic instead. The Octava seems to be a classic sort of mic that could seem to serve a better purpose than what you are presently using it for. A dynamic will be closer to what you use at gigs as well.

Go cheap.....
https://www.amazon.com/Behringer-Ul...0&qid=1560038492&s=musical-instruments&sr=1-2

or a little better.......
https://www.amazon.com/Electronics-...lectronics+V3&qid=1560038552&s=gateway&sr=8-3
 
Beware budget phantom power units. I would not call myself an "expert" but I have bought a couple of pups!
The problem is some PSUs do not deliver the standard rated current of 10mA. That Octavia requires 8mA and that is high by today's standards, most cap mics only need 1/4 of that. SO! Before you buy a spook juice box, buy a digital test meter*. A £10 one from Halfords will do. Then, ASK the vendor or the 48V supply if the box can deliver the standard current (they never 'king say!) and if not pass. If they say "yes" ffs test it when delivered (I'll tell you how).

By the very nature of an add on phantom power unit it MUST protect the downstream device, mic pre, from 48V and therefore will protect itself from any residual voltage.

But, I agree with Mark. A budget dynamic could be a better bet but, the "mechanic" might not be a good, low noise pre amp? The UR22 by all accounts is. Can you not borrow the band's dymo for a try out?

Other dynamics to consider:
Prodipe TT-1 about £30 and there is a Shure for about £20. My son in France uses one and it is comparable to an SM58. Not going to be AS good or as rugged of course for 80 quid or so less!

*I strongly and constantly urge musos to buy such a meter (and pay a bit more if you can). How TF people test pedal batts and check cables without one baffles me?

Dave.
 
We use multiple mixers for stage/recording work and use passive splits.its very common for both mixers to accidentally have their phantom power switches pressed. Nothing happens apart the pop on live mics. Electronically something does happen because the two voltages will have a small difference in level, increasing current flow in one or the other, but as the supply voltage is already 'floating' the change in drive seems to do nothing at all? If you draw out the circuit you are changing the resistance that creates the phantom voltage, which does put a small damping on the audio, but I have never noticed any audible impact.

One warning. I have had one Chinese phantom unit that doesn't have the capacitor DC blocking and the 48v went back to the mixer, which did nothing apart from make all the channel peak LEDs turn on!!
 
I could be doing the TC pre amp a disservice?

TC do make some excellent kit and the very well written specification attached suggest the unit does in fact have a very low noise pre amp.

Note however that the max input is necessarily lower than that on most AIs and mixers as a result of the low, 9V supply. This means that the Octavia might not in fact be a good choice anyway because it has a very high output of -20dB/Pa.

Deffo give a dymo a do before you spend out on a spook supply!

Dave.
 

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We use multiple mixers for stage/recording work and use passive splits.its very common for both mixers to accidentally have their phantom power switches pressed. Nothing happens apart the pop on live mics. Electronically something does happen because the two voltages will have a small difference in level, increasing current flow in one or the other, but as the supply voltage is already 'floating' the change in drive seems to do nothing at all? If you draw out the circuit you are changing the resistance that creates the phantom voltage, which does put a small damping on the audio, but I have never noticed any audible impact.

One warning. I have had one Chinese phantom unit that doesn't have the capacitor DC blocking and the 48v went back to the mixer, which did nothing apart from make all the channel peak LEDs turn on!!

Yes Rob, people do get exercised about phantom power and in most cases there is no problem.
THE biggest "danger" as you mention, is plops, can be bangs(!) through monitors and PA though once ears have recovered there is rarely any lasting damage. Valuable vintage ribbons and dynamic mics for that matter should be protected but even that is more an apocryphal story than hard fact?

So, rare but damage can happen. The input to a mic pre (or any other) should be protected by capacitors and diodes. However the protection is only up to the voltage of the internal supply rails, a max of +&-18V and generally lower than that in budget gear. The capacitors are also unlikely to be rated at no more than 22V and so phantom power could bias the input devices into "lockup" Again, permanent damage is unlikely but can happen.

Once again I shall be a boring old sod and say "you can only know/test for these thing with a FEKKIN' meter!"

Dave.
 
Hi guys.

Thanks for the advice. Very helpful

Rob: Yeah will prob steer clear of the chinese ones then

Dave & Mark: The thing I didnt mention (just to keep things simple) was I have the ur22 also running onto a DAW to make demos so I like having the Octava as it's sounds way better than a dynamic for recording as I have a big deep voice. Saying that, I could get a cheap dynamic for practising, then switch it out for the Octava when recording.

Dave: Yeah looking at first review here: Behringer PS400 – Thomann UK, at.7ma the Behringer PS400 will only generate 22v (less than the mic mechanic), so that's not gonna work - like you said.

Thanks

Masten
 
Well you got my curiosity up, so I popped the 'hood' on the PS400 so I could make some direct voltage measurements with a few mics at the XLR. (I keep saying I'm going to build a cable jig to do this).

The operating currents noted are from manufacturers specs. Coincidentally I have a CAD M179 which pulls 8ma like the MK-219.

No load volts = 47.3vdc.

MIC, Required current ma, Actual volts measured at PS400 XLR
AT2020, 2ma, 40.2vdc
AT3035, 3.5ma, 38.5vdc
KSM27, 5.4ma, 28.8vdc
CAD M179, 8ma, 4.52vdc

Did not try to see if mic was functional or sounded like crap. The voltage drops were reasonable and expected until the CAD M179 was connected. The PS400 power supply just sinks when it sees the 8ma load.

If the phantom power limiting resistors are the typical 6800 ohms in your UR22, the calculated voltage your MK-219 may actually get at the XLR may be about 20.8vdc based on two 6800 ohms resistors in parallel (3400 ohms) feeding the mic load (if I'm thinking this through correctly).
 
Last edited:
Well you got my curiosity up, so I popped the 'hood' on the PS400 so I could make some direct voltage measurements with a few mics at the XLR. (I keep saying I'm going to build a cable jig to do this).

The operating currents noted are from manufacturers specs. Coincidentally I have a CAD M179 which pulls 8ma like the MK-219.

MIC, Required current ma, Actual volts measured at PS400 XLR
AT2020, 2ma, 40.2vdc
AT3035, 3.5ma, 38.5vdc
KSM27, 5.4ma, 28.8vdc
CAD M179, 8ma, 4.52vdc

Did not try to see if mic was functional or sounded like crap. The voltage drops were reasonable and expected until the CAD M179 was connected. The PS400 power supply just sinks when it sees the 8ma load.

If the phantom power limiting resistors are the typical 6800 ohms in your UR22, the calculated voltage your MK-219 may actually get at the XLR may be about 20.8vdc based on two 6800 ohms resistors in parallel (3400 ohms) feeding the mic load (if I'm thinking this through correctly).


You are indeed thinking correctly Mark. It would seem the PS400 has a regulated supply but the supply to the regulator is not man enough. You don't say what the open circuit, no load voltage is Mark but my guess is around 47V (which is well inside spec) . The supply to the regulator hold up fine up to about 8mA.

Caveat bloody Emptor!

OP, if you want to use the Octava get a 10dB inline XLR attenuator as well as a supply AND CHECK IT! The attenuator will bring the level back to a "hot" dynamic. I am assuming you do not "kiss" the capacitor mic as you would a dynamic!

Dave.
 
Phantom powering is tricky and has several problems:
1. Phantom powering problem is reduced Phantom VOLTAGE. Without load it can be right +48V DC. But in case of Phantom's official max 10mA CURRENT's load std Phantom circuit provides under 15V DC VOLTAGE!
Most case it is not so critical for impedance convertor buffer preamp. But some pro condenser mics are using Phantom voltage as POLARISATION voltage and provide distortion or even not work at all!
2. Many (semi-pro and even some pro!) mixers/mixing consoles can not provide enough total Phantom CURRENT (not talking about voltage...) if several input channels (connected devices) are using higher current Phantom Power.
Because inbuilt power supply is too weak for total Phantom load, as result 48V stabiliser can not even stabilise voltage and you have low current + low voltage + pulsing 50/60Hz hum...
3. Phantom power can damage un-symmetric loads. The same can happen with less-transformer dynamic & ribbon mics in case of damaged (one signal wire shorted to shield/ground) mic cable.
 
Phantom powering is tricky and has several problems:
1. Phantom powering problem is reduced Phantom VOLTAGE. Without load it can be right +48V DC. But in case of Phantom's official max 10mA CURRENT's load std Phantom circuit provides under 15V DC VOLTAGE!
Most case it is not so critical for impedance convertor buffer preamp. But some pro condenser mics are using Phantom voltage as POLARISATION voltage and provide distortion or even not work at all!
2. Many (semi-pro and even some pro!) mixers/mixing consoles can not provide enough total Phantom CURRENT (not talking about voltage...) if several input channels (connected devices) are using higher current Phantom Power.
Because inbuilt power supply is too weak for total Phantom load, as result 48V stabiliser can not even stabilise voltage and you have low current + low voltage + pulsing 50/60Hz hum...
3. Phantom power can damage un-symmetric loads. The same can happen with less-transformer dynamic & ribbon mics in case of damaged (one signal wire shorted to shield/ground) mic cable.

Whilst it is true that the maximum 10mA draw would only leave 14V on the mic pins any mic manfctr would surely know this? They would therefore be running the electronics as "current source mode" and deriving the polarization voltage from a DC-DC converter. Not forgetting as well that many, quite expensive and decent capacitor mics use electret capsules these days. Then of course, Sennheiser use a completely different principle and need no polarizing voltage.

Yes, stories abound of ribbons being damaged by phantom power but actual, verifiable incidents are hard to find and of course, SOMETHING has to go wrong, open or short connection for badness to happen.

I have been told several times that BBC OB trucks used P48 on every XLR and it was not switchable. They used a vast array of mic types including the venerable 4038 and I am sure "steps" would have been taken had even just a few been killed?

Phantom power is perfectly safe when used correctly and by people who know their job. It is unfortunate now that gear delivering spook juice has fallen easily into the hands of people who do not. However, if those people take the time to learn a tiny bit of electronics theory AND get a frigging meter! Their kit will stay safe.

Dave.
 
You are indeed thinking correctly Mark. It would seem the PS400 has a regulated supply but the supply to the regulator is not man enough. You don't say what the open circuit, no load voltage is Mark but my guess is around 47V (which is well inside spec) . The supply to the regulator hold up fine up to about 8mA.

Caveat bloody Emptor!

OP, if you want to use the Octava get a 10dB inline XLR attenuator as well as a supply AND CHECK IT! The attenuator will bring the level back to a "hot" dynamic. I am assuming you do not "kiss" the capacitor mic as you would a dynamic!

Dave.
You know, I did measure it, wrote it on a piece of paper, and then just forgot to note it in the post...... No load volts = 47.3vdc. Going to edit the post so it has all the measurements.
 
Hi

Ok thanks for the info guys. Is going a bit over my head now to be honest. My knowledge of electricity is I know that Amp x Voltage = Watts. That's about it.

Mark: so are you saying that with this result:
CAD M179, 8ma, 4.52vdc

There's no way the PS400 will make an Octava Mk-219 work properly as the voltage is way too low?

What I dont get is that if I plug the Octava directly into the UR22 there's no problem at all (there's only the hissing when it's running off the Mic Mechanic) No hissing, no noise and thats running off USB power so how come a dedicated unit like a Behringer PS400, that has more power going into it, couldnt power it?

Thanks

Masten
 
Hi

Ok thanks for the info guys. Is going a bit over my head now to be honest. My knowledge of electricity is I know that Amp x Voltage = Watts. That's about it.

Mark: so are you saying that with this result:
CAD M179, 8ma, 4.52vdc

There's no way the PS400 will make an Octava Mk-219 work properly as the voltage is way too low?

What I dont get is that if I plug the Octava directly into the UR22 there's no problem at all (there's only the hissing when it's running off the Mic Mechanic) No hissing, no noise and thats running off USB power so how come a dedicated unit like a Behringer PS400, that has more power going into it, couldnt power it?

Thanks

Masten

Yeah, I don't think the MK-219 would cut it with the PS400. If I get a chance I'll give the CAD M179 a try to see if it will function with the PS400. The spec sheet for the CAD states it will work in a range of 24 to 48vdc, but I have serious doubts it will do anything with just 4.5 volts.
Your UR22 likely has a better power supply than the PS400, but if I were to guess, I'd bet if you had a second MK-219 to plug in and try to power, the UR22 may not like it and not provide enough voltage.
 
There's a review on the Thomann site that supports the above comments. not a wonderful unit with mics demanding the full current indicated in the spec.
Just recently bought the PS400 for supplying phantom voltage to various condensor microphones. In brief: rugid built, however not meeting decent electrical specifications.
- Output voltage (unloaded) equals 12V in 12V-mode, but only 31V in 48V-mode, i.e. much too low! A short check of the internal electronic circuits shows a multi-diode trippler, thus limiting the output to 3x the input voltage, i.e. 36V max. It never will/can reach 48V, as claimed!
- The output voltage STRONGLY depends on microphone current drawing! E.g. in 12V-mode the voltage drops from its unloaded 12.0V to 10.4V (at 5 mA) and 8.5V (at 10mA).
But much more serious in 48V-mode: from 31V (unl.) to 22V (at 0.7 mA) and 12.5V (at 2 mA)! Note that common microphones typ. require 2-5 mA at 48V!
- Noise level is OK, both at 12V (adapter) as well as 9V (battery); at 9V unloaded output voltage is just 9V or 25V (select switch 12V- or 48V-mode).
Fazit: at "48V" setting the unit can not be used. Likely many people will be affected by this deficit, without knowing.
 
"Ok thanks for the info guys. Is going a bit over my head now to be honest. My knowledge of electricity is I know that Amp x Voltage = Watts. That's about it."
That's pretty much it Marsten. Ohm's Law. That is all you need to work out phantom power voltages although the process is a bit convoluted.

Take our maximum spec of 10mA and 48V (the standard allows + or - 4V). The actual 48V supply in the AI/mixer/PSU should be capable of at least that current for each XLR outlet. From said supply are two 6,800 Ohm resistors, one in each "leg" pins 2&3. To K.I.S.Sir we can just combine them as a single 3,400 Ohm resistor (3k4) .

Now, mA times k = V so 34V is dropped across the 3k4. Take that from our so-so solid (ha!) 48V and you get 14V at the pins of the mic.

In theory, when any piece of gear go for a review the phantom power delivery should be checked for each mic input for voltage at max load current. Now, I can see that this is tedious for a 32 input mixer but they SHOULD do it. In practice they never do it even for a 2 mic input AI!

I have been messin' with this stuff long enough to know that ten or so years ago AIs had pretty poor mic pres, at least at the budget end did say, sub £200? Every time one was reviewed the lack of gain and poor noise performance was, rightly, commented on. Result? You can now by a 2 mic input AI for less than £80 with very good pre amps that will work with a dynamic mic, at least for close talk/singing and cabs.
"They" do listen if the right people make enough noise!

Dave.
 
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