Topic: AT853Rx phantom power circuit. Transformers inside?

[poorlyconditioned]

Has anyone looked inside the AT853Rx phantom power adapters?  If so, is there a transformer inside?  I just looked at the docs for the SM-4 adapters and they do have a transformer.  I'm assuming this is not so good, at least with low end brands like Samson.

By the way, I'm currently running a pair of AT853 with battery power (9V battery with a *proper* 3 wire circuit) and they work great.  So good, that I bought a second set with the phantom adapters.  I plan to use the batt. power ones for stealth and the phantom ones for open taping.  I haven't got them yet though.  When I get them I'll certainly open them up for a look...

  Richard

[leegeddy]

Has anyone looked inside the AT853Rx phantom power adapters?  If so, is there a transformer inside?  I just looked at the docs for the SM-4 adapters and they do have a transformer.  I'm assuming this is not so good, at least with low end brands like Samson.

By the way, I'm currently running a pair of AT853 with battery power (9V battery with a *proper* 3 wire circuit) and they work great.  So good, that I bought a second set with the phantom adapters.  I plan to use the batt. power ones for stealth and the phantom ones for open taping.  I haven't got them yet though.  When I get them I'll certainly open them up for a look...

  Richard

yes. there is a tranformer inside the AT853X series adaptors.

>>9V battery with a *proper* 3 wire circuit

is there an improper way?

marc

[poorlyconditioned]

Has anyone looked inside the AT853Rx phantom power adapters?  If so, is there a transformer inside?  I just looked at the docs for the SM-4 adapters and they do have a transformer.  I'm assuming this is not so good, at least with low end brands like Samson.

By the way, I'm currently running a pair of AT853 with battery power (9V battery with a *proper* 3 wire circuit) and they work great.  So good, that I bought a second set with the phantom adapters.  I plan to use the batt. power ones for stealth and the phantom ones for open taping.  I haven't got them yet though.  When I get them I'll certainly open them up for a look...

  Richard

yes. there is a tranformer inside the AT853X series adaptors.

>>9V battery with a *proper* 3 wire circuit

is there an improper way?

marc

I guess 3-wire is the proper way.  I've just seen a lot of 2-wire stuff, and there is no excuse for that!

Anyway, what is the opinion on these transformers.  We should avoid them if possible, right?  I know the people over at micbuilders (Yahoo group) have schematics for transformerless phantom power circuits.  So, my hunch is we should run battery power for short runs (eg., stealth from your hat to your pocket) and phantom power, witthout transformers, for longer runs.

Comments?

  Richard

[jk labs]

Has anyone looked inside the AT853Rx phantom power adapters?  If so, is there a transformer inside?  I just looked at the docs for the SM-4 adapters and they do have a transformer.  I'm assuming this is not so good, at least with low end brands like Samson.

By the way, I'm currently running a pair of AT853 with battery power (9V battery with a *proper* 3 wire circuit) and they work great.  So good, that I bought a second set with the phantom adapters.  I plan to use the batt. power ones for stealth and the phantom ones for open taping.  I haven't got them yet though.  When I get them I'll certainly open them up for a look...

  Richard

yes. there is a tranformer inside the AT853X series adaptors.

>>9V battery with a *proper* 3 wire circuit

is there an improper way?

marc

I guess 3-wire is the proper way.  I've just seen a lot of 2-wire stuff, and there is no excuse for that!

Anyway, what is the opinion on these transformers.  We should avoid them if possible, right?  I know the people over at micbuilders (Yahoo group) have schematics for transformerless phantom power circuits.  So, my hunch is we should run battery power for short runs (eg., stealth from your hat to your pocket) and phantom power, witthout transformers, for longer runs.

Comments?

  Richard

No comment :-)

But I do have a trick question:
why did Samson opt for an impossibly cumbersome $4 transformer requiring lots of manual labor both in mounting and final assembly
when they could have opted for a nice small machinemountable solution using only 50 cents worth of parts?

[dklein]

damn I hate those trick questions
It feels like I'm in school.

hmmm....
Impedance can be set thru components right?
A noise thing? - it's balanced and 3 wired.
Is there some voltage step up through the transformer?  Or is this where they're creating the balanced source?

[cgrooves]

Not talking SP mics here:
If you were to run 48v phantom power directly to an AT853 without going through one of the AT power modules (supplied with the AT mics) wouldn't it fry the mic?

As for the SP mics:  Does the Samson device that comes with their AT853 based mics act like a power module, or a low to hi Z transformer?

BTW, I have to transformers on my AT's in order to get good levels going line-in on my m1, whether running phantom or just from the AA batteries inside the AT power modules.

[poorlyconditioned]

Not talking SP mics here:
If you were to run 48v phantom power directly to an AT853 without going through one of the AT power modules (supplied with the AT mics) wouldn't it fry the mic?

As for the SP mics:  Does the Samson device that comes with their AT853 based mics act like a power module, or a low to hi Z transformer?

BTW, I have to transformers on my AT's in order to get good levels going line-in on my m1, whether running phantom or just from the AA batteries inside the AT power modules.

The AT and the Samson are both "phantom power modules", to power the mics (approx 9V I think) and "impedance balancers" to convert the mic signal from an unbalanced to a balanced signal that can go on long cables.  Neither have any gain.  You can get gain from a preamp, or from transformers.  Or from putting the mics in front of very loud sources I guess.

What I was suggesting is using a transformerless phantom power circuit instead of the AT/Samson ones.  Actually I trust AT to provide a good one, but I'm not sure how good the Samson one would be.  I would certainly check before inserting it in between and AT mic and any decent preamp though.

  Richard

[§†∑∫åµÞ≥¥]

Has anyone compared the Samson unit's to the AT's? I'm thinking about making this change to my SP AT933's but am wondering the difference between the two brands other than the Samson's being 1/3 the price. Thanks.