Adapting a microphone to remote phantom power

It's 'proprietary' not a standard.

Graham

On 4/10/2009 10:13 PM Eeyore spake thus:

To reply to you mis-attributed post (the person you responded to is not the owner of the Sony mike): Well, duh. Who ever claimed that Sony's "plug-in power" scheme was standard? In fact, I've been taking particular pains to point out just the opposite.

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On 4/10/2009 10:12 PM Eeyore spake thus:

How is "computer mike" power different from Sony's "plug-in power"? In both cases the DC to power the mike's electronics is carried on the signal line. Looks, sounds, smells like phantom power to me.

You're only confusing things by saying that it's "very different from [my] ECM". THAT'S THE GODDAMN POINT I'VE BEEN TRYING TO MAKE! The mike I have ignores the phantom power supplied by my recorder; I'm thinking of ways to rectify that situation. That was the whole point of this exercise.

Got it now?

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I know. Maybe I should have said 'This Sony mic' ?

Doesn't change the fact that a quality ( i.e. not a Duracell AA battery ) would be your simplest fix.

Graham

If you go to any supplier who knows about microphones - including a music shop type place - and ask for a phantom powered mic you'll get a balanced one which works with phantom power. And only phantom - not some other form of line powering.

Would you go to a greengrocer and ask for apples and be happy to be given oranges?

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    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Not my Sony mic but Mr Nebenzahl's one. ;-)

There's more to the IEC standard than just the parameters of phantom power. After years of makers going their own way, conforming mics all have the same output level and phase - as well as connectors. In other words you can choose the mic best suited to an application and substitute it for another conforming make and be certain it will work properly. With all the various other methods of line powering this isn't so.

This doesn't mean all mics are the same. Horses for courses. But at least you don't have to get the soldering iron out just to get some sort of output.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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I'm suggesting it's probably the same thing.

It's not TRUE phantom power. True phantom power requires a balanced signal. Read it up. I've been trying to be practical and helpful and all you can do is bitch at me. Go learn some FACTS !

If you don't understand the above don't bother coming back to whine at others.

Graham

I said much earlier on that the mic must be designed for line powering. And presumably that Sony isn't. Since the machine supplies line powering it's obviously designed to be used with another mic.

My feeling is there is a good reason. A couple of volts at low current isn't going to power a good quality mike handling high SPL. It's really restricted to lo-fi use. If you up the voltage by using an inverter inside the mic you're then into higher current from the source which could cause problems with the existing connectors - and the possibility of damage to a moving coil mic used on that input.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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On 4/11/2009 12:53 AM Dave Plowman (News) spake thus:

Obviously, yes. And as I said, it was my mistake for not buying a powered mike, instead of mine that requires a battery (plus remembering to turn the damn thing on when recording). It does work fine with this mike.

I'm not contemplating modifying the recorder to supply higher voltage; I'm considering rewiring the mike to use the recorder's power rather than the mike's battery. The mike already incorporates a DC-to-DC converter (1.5 volts--> 4.8 volts).

And as I said before, presumably a moving-coil mike wouldn't be damaged by the 2.8 volts the recorder is sending out.

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Then you would need a phantom power supply.

At 1 mA or so probably not but it wouldn't work properly.

Graham

It's almost certainly a better quality mic than the one designed for the machine.

FWIW, the first battery powered mic I came across (in pro use) was the Sony ECM50 - a small personal mic and the first anything like as small at decent quality. Those were battery powered with no off on switch. Used a mercury cell. Think it lasted at least a year.

It's *possible* some could be if you modify the current limiting resistors to supply enough current for the convertor in your mic. And will that convertor work properly off the (highish) impedance of that supply? It's a bit of a minefield...

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    Dave Plowman        dave@davenoise.co.uk           London SW
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The last place I would go would be to a music store. You should see the abortion a local 'Music Store' stuck our local Veteran's Park with.

Apparently they have been giving you crabapples, and you don't know the difference.

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On 4/11/2009 12:50 AM Eeyore spake thus:

Read

bitch at

Ah, the beauty of Wikipedia, the "encyclopedia" any junior-high-school idiot (or electronics engineer with an axe to grind) can edit. Looking at that article's revision history, one sees an awful lot of editing by "anonymous IPs"; what are the chances that one of those is *you*, eh?

Ah, there it is: now you're stooping to throwing insults. By "you don't understand", of course, you mean "you dare to disagree with my version of things".

So let's see what others have to say about "phantom power", shall we? A good starting point is to let Google sort it out: a simple search with "define:phantom power" yields the following:

o the Wikipedia article, which agrees with you o

which says nothing about the balanced requirement (agrees w/me) o ditto o agrees w/you o which agrees w/me (except for the odd assertion that "Phantom power can only be used when the connectors are XLR" (???)

DISCLAIMER: I make no claim that any of the above "citations" are authoritative (least of all the Wikipedia entry). My intention is to show that, contrary to your (and Dave Plowman's) insistent assertions, there seems to be no general agreement that the term "phantom power" is as restrictive as you claim it is. (See Arfa Daily's postings on the subject for corroboration.)

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On Sat, 11 Apr 2009 11:21:20 +1000, Franc Zabkar put finger to keyboard and composed:

WM-D6C Sony service manual:

Supplement:

The supply for each of the L and R microphone inputs is derived from a buffered, zener regulated 2.6V source. The series resistor is 7.5K. For comparison purposes, the condenser elements within Sony's ECM-737 mike are each powered from a 4.8V supply via 10K resistors.

I thought that the OP may be measuring the voltage while the mike was connected, but it appears that 2.8V was the O/C voltage of the Walkman.

This is the relevant section of the circuit:

2.6V |-- 7K5 --> L IC201 | | 5.9V o--- R ---+---------+---- buffer -+- 1K ----+---| | | | | ZD --- 220uF 47uF --- |-- 7K5 --> R HZ3ALL | --- --- _|_ _|_ _|_ = = =

The HZ3ALL zener voltage rating is 2.5V (min) - 2.9V (max):

- Franc Zabkar

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On 4/11/2009 1:48 PM Franc Zabkar spake thus:

Franc; after this post, I have to tell you this: I think you should get out of this newsgroup. You don't belong here.

Why? Because you

o Post helpful answers to questions asked here o Seem extremely competent and knowledgeable about electronics o Don't engage in insulting those you might consider beneath your respect, or who might disagree with you o Come up with *really* useful sources of information.

In short, you're out of step with the program here.

All joking aside: many thanks for this very useful information.

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Which part of 'including' don't you understand?

You claim to be some sort of engineer but are happy to misuse a technical term? Fine. You should be selling 'hi-fi' cables.

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    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

They use whatever term they pick up, and it varies by region. The proper name would included 'balanced', but doesn't becasue it wasn't used by the devices they solte the name from. I'll bet you use 'DB-9 connectors', too.

What part of idiot don't you understand? I owned a commercail sound & industrial electronics repair business for about 15 years. I never advertised the business, and made the better part of my income cleanong up the messes left behind by self proclaimed 'Audio Experts' and 'music stores'. Word of mouth brought me customers from 100 miles away. The business didn't even have a listed telephone number, since the shop work was done in my home.

That is something I've never done. Have you ever designed anything Mil-spec, or built a commercial radio or TV station?

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Ah. That explains things. Perhaps if you actually used those mics in anger you'd know what to ask for.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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The only electronics I used in anger was in the US military. The anger was due to the twisted 'catch 22' regulations of zero allowed downtime, and everything being 'depot level maintenance. If you had the proper security clearance you would see how I handled the problem, and the results of my decisions.

I know what to ask for, even when some fool has given it a stupid name.

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And another motherboard bites the dust!