External Phantom Power...recommendations?

[Jamz]

I am currently looking at external phantom power supplies. Specifically, the Stewart PM2. Wouldn't need it very oftern. However, I have an older API rack that is not wired for phantom power and recently picked up the AEA TRP. My thoughts are to have enough external Phantom power for (2) microphones in the event I wish to use my API 512s or TRP with a mic that requres it.
Any suggestions?
Anyone here use the Stewart PM2?

[HudHudson]

Audio Technica makes a few models, I used one with a pair of Tele V76s that came in the original rack:

http://stores.nextag.com/zZounds/pro...oduct=65192043

[squeegybug]

A-T CP8506 here. Very nice high quality unit, 4-channel.

Steve

[drBill]

Jim, I have a unit that I've used for that exact same purpose (500 rack w/o 48v). I sold the rack and have the unit FS for $25 plus shipping and paypal. If you're interested PM me.

As for the units, I think any of them will work equally well. All your'e doing is injecting 48V into the mic line.

Bill

[Jamz]

Originally Posted by drBill

Jim, I have a unit that I've used for that exact same purpose (500 rack w/o 48v). I sold the rack and have the unit FS for $25 plus shipping and paypal. If you're interested PM me.

As for the units, I think any of them will work equally well. All your'e doing is injecting 48V into the mic line.

Bill

What unit is it?

[squeegybug]

There can be a bit to P48 supplies. Lynn Fuston wrote a nice article here:

http://www.eqmag.com/story.asp?secti...storycode=7671

Steve

[dbbubba]

A bit to 48v supplies?

Hell, I built my own.... works great!
A simple project really.

Danny Brown

[squeegybug]

Sure it's simple. Problem is, many mixers or standalone PS don't always have robust designs or components for P48. I've worked with lots of folks who are having problems because they can run certain mics fine on one system and not on another. Or maybe a certain number of particular mics. Almost always a phantom power issue.

Steve

[Jamz]

I ordered a Stewart PM2.
Anyone ever use it?

[jjochems78]

i fail to see what difference one power supply would make compared to another. how could it possibly help the sound out. someone want to fill me in?

[Sizzleboy]

Originally Posted by jjochems78

i fail to see what difference one power supply would make compared to another. how could it possibly help the sound out. someone want to fill me in?

It's about the amperage. I don't think it will matter with a single mic, but alot of desks skimp on the total amperage available for FP and so when alot of mics are used, you have problems.

[Jamz]

I personally wasn't so much concerned about the sound as I was protecting the pre.
I picked up an AEA TRP. Great deal and sounds excellent. Made for (but not exclusive) for ribbon mics. It has no phantom power on board. Fred Forssell designed the unit for Wes Dooley at AEA. Wes is encouraging the TRP be used with both ribbon and non ribbon mics. I decided to look into an external phantom power supply. In part of Fred's response (on another forum) he had this info on external phantom.

"There is no internal phantom power available with the TRP and it has no phantom blocking caps at its input. Therefore, if you use an external phantom power box this box needs to provide the DC blocking caps. Because the TRP have VERY high input impedance, these caps can be quite small (like 3.3 - 10 MFD/63v) and wired into an XLR barrel connector or had made cable, should the external phantom power box not provide the blocking. Also custom external high voltage DPA/B&K supplies (with DC blocking) can also be used with good success."

[Sizzleboy]

Originally Posted by Jamz

I personally wasn't so much concerned about the sound as I was protecting the pre.
I picked up an AEA TRP. Great deal and sounds excellent. Made for (but not exclusive) for ribbon mics. It has no phantom power on board. Fred Forssell designed the unit for Wes Dooley at AEA. Wes is encouraging the TRP be used with both ribbon and non ribbon mics. I decided to look into an external phantom power supply. In part of Fred's response (on another forum) he had this info on external phantom.

"There is no internal phantom power available with the TRP and it has no phantom blocking caps at its input. Therefore, if you use an external phantom power box this box needs to provide the DC blocking caps. Because the TRP have VERY high input impedance, these caps can be quite small (like 3.3 - 10 MFD/63v) and wired into an XLR barrel connector or had made cable, should the external phantom power box not provide the blocking. Also custom external high voltage DPA/B&K supplies (with DC blocking) can also be used with good success."

That's interesting. On the top of my TRP, it reads "Do not externally supply phantom power as it will be shorted by an input protection circuit"

[Jamz]

Originally Posted by Sizzleboy

That's interesting. On the top of my TRP, it reads "Do not externally supply phantom power as it will be shorted by an input protection circuit"

You're absolutely correct. That's why I'm asking about Phantom units. I don't know enough about electronics to know if the DC blocking caps Fred is speaking of are something provided only in special units. If they're not in your "normal" store bought phantom units perhaps that explains why the TRP has that caution printed on the top. Maybe Fred was offering the inside scoop on the out-of-ordinary specifics needed in order for it to work with the TRP. I sent Wes an email to clarify.
Either way, I realize AEA built this pre with ribbons in mind and they went through the trouble of leaving phantom off. If I have to use another pre for mics that require phantom that's OK by me. I'm thrilled with the performance of the TRP and am actually considering a second unit. I could alsways use the Stewart PM2 with my API 512s.

[Jamz]

Wow! got a fast response back from Wes Dooley concerning the external phantom.

[ Jim,
*
The Stewart phantom supply does not work as there is no internal*phantom blocking on it.* Our preamp's protection circuit is a set of*internal zener diodes will*limit the phantom power voltage*to around 10 volts.*
*
Fred's suggestion of using external capacitors is good, if you have to try a phantom powered mic on The Ribbon Pre.
*
The HP filter is 12 dB per octave and set for 75 Hz.** We had comments that a higher frequency would be more useful for moderating the proximity effect for a close vocalist.* We've experimented and are starting to use a 100 Hz knee on the most recent production units.]