Steve, certain top-end recording condensers work ONLY with 48v power.... specially those built "like they used to build 'em" in the old days.

Paul, if you do have some of those condensers, you're better off getting an inline phantom supply. As good as Bose system is, it is built around the newer standards. Is the mic you're trying to power a Shure or Sennheiser/Neumann mic?
John,

That's really good advice to which I'll add, I'd leave the high end (expensive) studio mic at home.

We've tested a few of these and, if my memory serves me well, most work fine on 24V but a few of them really do need a 48V supply (that usually comes with them when you buy them).

Steve
Good point, Mark. 'Goes to show the value of industry standards. One of my old fav small-diaphragm condensers, the Neumann KM84, works great with 48V phantom, but doesn't sound happy at all with 24V. I've tried lots of mics and this seems, in my experience, to be a rare exception...
Hi Mike,

quote:
So, DOES the Bose phantom power supply the Sennheiser/Neumann properly?

Thanks, Mike


The Neumann KMS 105 sounds / works great with the the phantom power supplied by the Bose PS1 Power Stand. If you are considering the wireless Neumann/Sennheiser system it is self-powered for the hand-held unit so the phantom power from the Power Stand isn't used.

I can attest from direct personal experience that following condenser mics all work well for me with the Bose System:

AKG C451 (small diaphram condenser - great for Acoustic Guitar, drum overheads, etc)
AKG C535
AKG C1000S
AKG C3000B
Microtech Geffel UMT 70S* (a beauty in the studio - very similar to the Neumann U87)
Neumann KMS 105
Neumann KM 184 Updated version of the KM84 Chuck mentioned above. Try a matched pair of these on an Acoustic Guitar sometime - whew!
Neumann U87*
Rode S1
Shure Beta 87a
Sony C48* (lesser known, this is a really nice studio mic ~ $1700 USD)

I tried everything in my mic drawers when I got the Bose System. Some of the mics are more obscure than the list above. All worked well.

To echo Steve's thoughts - anything I've encountered that is *really* fussy about phantom power, comes with its own power supply.

* wonderful for recording in the studio - wouldn't use for live applications for vocals.

multiple edits as I added links
quote:
Originally posted by Steve-at-Bose:
John,

That's really good advice to which I'll add, I'd leave the high end (expensive) studio mic at home.

Steve


I agree as well... most of the mics that NEED a 48v system are better left in the studio.

The Neumann "head" needs a 48v power supply, and is used for recording... I doubt it'll sound great as a "live" mic. And even if it does, kinda pointless having a $10,000 mic just for live reinforcement.

I'm partial to Shure mics for live sound due to their low-cost, rugged design, and good over-all sound. I look to Sennheiser/Neumann for recordings since I'd rather not have any of those expensive mics ruined by beer or other touring hazards.
quote:
Originally posted by JohnL:

I agree as well... most of the mics that NEED a 48v system are better left in the studio.

The Neumann "head" needs a 48v power supply, and is used for recording... I doubt it'll sound great as a "live" mic. And even if it does, kinda pointless having a $10,000 mic just for live reinforcement.

I'm partial to Shure mics for live sound due to their low-cost, rugged design, and good over-all sound. I look to Sennheiser/Neumann for recordings since I'd rather not have any of those expensive mics ruined by beer or other touring hazards.


If you are refering to Neumann's dummy heads (the original KU80 or the revised version, the KU81) I can assure you that these work just fine with 24 Volts. If you have no phantom, the head can be run off any old 9V battery adn it actualy has a battery compartment for that. The only difference is the max SPL that you can record which is somewhat higher with 24V and even more so with 48V. In all my work with this head, that was never an issue.

You've certainly got to be careful with those when taking them on the road. One of the guys I worked with dropped one while we were measuring concert halls in Europe. The thing shattered completey and we had head fragments spread out over four rows of seats. But that wasn't a Neumann head. This particular specimen was from Head Acoustics and, among other things, even more expensive than the Neumann KU81 Wink
Steve-At-Bose wrote,
quote:
The reason we choose 24V is because the IEC (International Engineering Contsortium) has asked manufacturers to develop new product to a 24V standard.


What would have been the disadvantage in using 48v phantom in the PAS?
My Midas console uses 48v and I can't think of a major console manufacturer that has gone to using 24v instead of 48v. Why do you think there is resistance in following the IEC request?
Robert L
quote:
Originally posted by Steve-at-Bose:
The reason we choose 24V is because the IEC (International Engineering Contsortium) has asked manufacturers to develop new product to a 24V standard. Click here for more specifics.
Steve


Not to add fuel to the fire, but here is a quote from Schoeps:

"An international standard "24V" does not exist."

I did spend some time on the IEC website to see if I could confirm or deny this statement, but the IEC does not cater to mere mortals such as I. I could find references to the existing standard, but nothing to any new or proposed standards. If I had found something, it appears that I would have been asked to support the functions of the IEC with a financial donation before I would have been able to look at it anyway.

Thoughts?

Mike
quote:

What would have been the disadvantage in using 48v phantom in the PAS?


Robert, I think that if this 24V proposal is actually gaining traction, the reason for it is to align the phantom power voltage to be within what has become the international limit for "low voltage", 25V. "Low voltage" wiring requires no special provisions for protection etc., whereas voltages above this limit do.

I'll look into some flexible conduit solutions for your 130V DPA mics. Smile

Mike
quote:
Originally posted by MTM:

Not to add fuel to the fire, but here is a quote from Schoeps:

"An international standard "24V" does not exist."

I did spend some time on the IEC website to see if I could confirm or deny this statement, but the IEC does not cater to mere mortals such as I. I could find references to the existing standard, but nothing to any new or proposed standards. If I had found something, it appears that I would have been asked to support the functions of the IEC with a financial donation before I would have been able to look at it anyway.

Thoughts?

Mike

The standard is IEC 61938 in its 1996 revision (which is the latest,
section 7.4 "Phantom Supply systems" and specifically section
7.4.5. Preferred value of the supply voltage
quote:


Although 12V and 48V are still in use, 24 V systems are preferred for new developments.


The cheapest source for the standard that I could find is directly from ANSI
http://webstore.ansi.org/ansidocstore/product.asp?sku=I...Ed%2E+1%2E0+b%3A1996 but it's still $81.

I guess the main reason why most manufacturers still do 48V is the same reason why the US still uses the imperial and not the metric system. The metric system is (at least in the opinion of most of the world, including nearly all scientist) the better choice, but there is a certain pain in the transition and it takes a lot of work to change people's perception of "how things have to be done".

The orginal 48V/6.8KOhm spec was based on condenser mics requiring external polarization voltage. That's pretty much a thing of the past. Nearly all condensor mics are permanently charged and phantom is just used to power an internal preamp that acts as an impedance matcher.

For that purpose, 48V is actually a pain in the neck and it adds cost and complexity for no benefit whatsoever.

The other reason why 24/1.2kOhms is better, is that it allows higher current draw enables phantom to conveniently power all sorts of small outboard gadgets.

Hope that helps

Hilmar
Warning: lots of engineer babble and math ahead.

While we're at it: Here is another example of why 24V tends to work better in many situations. Let's assume you draw 10 milliamps of the supply. Since the 48V standard prescribes a 6.8 kiloOhm resistor there is lots of voltage drop on the resistor and the usable voltage at the output of the supply drops down to 14V. In the 24V/1.2kiloOhm case the voltage drops is much lower and you end up with a useable output voltage of 18V.
In this case, the 24V standard provides actually more voltage to the device than the 48V standard.
quote:

Hope that helps

Hilmar


Well, it helps me, but doesn't seem to say much to Schoeps, Earthworks, or DPA, whose latest products all use 48 V (or more). These three manufacturers make the best sounding microphones available. They make a lot more microphones than I do.

Go ahead. Have a listen. I'll wait here. What's that? Oh. Yes. Absolutely. If I were making all or part of my living from live performance with a handheld microphone or instrument microphone, I would use one of these products. Any of them would be a lot cheaper than my guitar/piano/flute/violin/traps/insert the name of your instrument here. Alan Steinberger would insist that I add the brand new Royer SF-24 phantom powered stereo ribbon to the list of best sounding microphones. He, of course, would be absolutely right about the sound (but I wouldn't use one on stage). Doh! Works on 48 V phantom power ONLY.

Might I suggest that high voltage phantom power is not a "thing of the past" serving "no benefit whatsoever"?

You do something to gain something to lose something. Smile

Mike

PS

Here is what DPA has to say (emphasis mine):

"However, in a lot of situations, the 48V phantom was also too limiting to be used for supply voltage in the preamplifier design. Purists are expecting clarity, transparency, very low distortion, and above all, an extremely wide dynamic range. It was therefore decided that the Series 4000 Microphones should offer two different lines: a cost-efficient 48V phantom range for the many pro audio users, and a hi-voltage (130V) range for the purists' applications."

PPS

More arcane facts for sake of completeness:

Schoeps and Earthworks attest that their mics will work at 24 V — assuming a properly designed supply — but performance will not be optimal. Even more intriguing, most Schoeps mics are designed for 12 V OR 48 V. Operation at 24 V is undefined.
Mike

Of course you are right in pointing out that it's big benefit when the microphone actually works with the amp Smile
My remark of "no benefits whatsoever" was aimed at the technical merits of 48V and even there I probably got a little carried away.

There are applications where higher voltages make sense. For example our B&K (now DPA) measurement mics use 200 Volts, and they can stomach 150 dB SPL and have a noise floor of 15 dB SPL. That's great for a wide range of professional measurements, but overkill for any normal audio application and it ain't cheap either Smile.

All I was saying is that there actually is a standard and it specifically states 24V as the preferred voltage and that there are very good technical reasons that the standard was written that way.

But since nobodys follows the standard, it's a pointless discussion and the only thing that is important is: Does 24V work ?

By and large the answer is yes and I'd be hard pressed to find a mic that has problems with that. If phantom is used to power the preamp, 24 V will work no matter what the manufacturer says. We've tried mics that are specifically speced for 48V and they do perfectly fine with 24V. There is no technical reason why they shouldn't or result in any degradation. The only difference is a reduction in max SPL. However, if you are out of steam on a 24 V supply, a 48V or even 130 V won't help much if the next element in the chain can't take that voltage either. Most somewhat reasonable equipment doesn't and will simply clip.

So there are cases, where higher phantom voltage can make sense, but they tend to be rare and require a very expensive and carefully matched overall setup to get any benefit out of it. It's not likely you will run into one of those in a typical Live Music situation.

Hilmar
quote:

But Mike, weren't we discussing recording or amplifying a church organ, and pairing the Royer with a comparable snazzy mic pre as well?


Yes, we were. That's why I said I wouldn't use the Royer mic on stage. However, since I realized that the way that I had phrased the first paragraph, it looked like I didn't think the Royer was in the "best" category, I thought I had better update the list with the caveat.

Of course it was only coincidental that talking about that mic bolstered my argument. Smile
Hilmar, I have written and discarded three replies.

While technically interesting, they could also be accused of being argumentative, and, in any case, would not further the discussion.

While other firms disagree with the IEC suggestion (the phrasing is clearly not a "standard"), Bose's mind is made up on this issue, and it is unlikely to change.

I'll simply like it or lump it.

Mike

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