Topic: Newbie with a question.........

[Tye]

I was just wondering if it was possible to power a preamp that is 9VAC @ 0.8A with a battery pack? I was curious because I don't want to get stuck at a show that does not have power available(I'm sure its rare). I was thinking maybe there was an adapter to plug into the preamp. Would it need too many batteries or is there something like that out there?
              Thanks

[BCostigan]

9 volts AC???   That's tough to come by no matter where you are!   Are you sure that it's AC and not DC?  What pre are you talking about...I'd (and I'm sure others) would be able to help more if we knew what piece of gear you're referring to specifically.

I'm guessing the pre actually needs 9 volts DC and has a wall wort?

[Tye]

I'm positive it is 9VAC here is the link to the specs
http://img3.musiciansfriend.com/dbase/pdf/spec/180610.pdf
Are'nt RC cars run on 9VAC. It can't be 9VDC it does not take batteries.
 Which one should I use?
            Thanks

[Tye]

Oh just in case you don't have Adobe here's a link to a pic and specs
http://artproaudio.com/products_main.asp?cat=1&id=58&type=79&show=
SPECIFICATIONS:
Dimensions: 5.0"D x 5.5"W x 2.0"H
Weight: 1.5 lbs
Dynamic Range: >100dB (20Hz to 20kHz)
Frequency Response: 10Hz to 20kHz (+0,-1dB)
THD: <0.1% (typical) > CMMR: >75dB (typ @1kHz)
EIN: -129dBu ('A' weighted XLR to XLR)
Maximum Gain: 70dB (XLR to XLR typical)
Maximum Input Level: +14dBu (XLR), +22dBu (1/4")
Maximum Output Level: +28dBu (XLR), +22dBu (1/4")
Input Impedance: 2k ohms (XLR), 840K ohms (1/4")
Output Impedance: 600 ohms (XLR), 300 ohms (1/4")
Power Requirements: 9 VAC @ 700ma (typ)

[Brian Skalinder]

Power Requirements: 9 VAC @ 700ma (typ)

To run this in the field, you'll need a battery pack and a DC > AC converter.  I don't have any experience using one, however, so I'm not much help on the specifics.  I remember it coming up in the past, maybe try searching old threads, but I'm not sure how much detail there will be.

If you're going to run this in the field all the time, I'd consider picking up a DC-powerable preamp instead.

[Tye]

Thanks for the help brian.
 I tried to find a decent DC preamp but could not find much. I like the feautures on this preamp so I'll probably run this in the field for a while.

[Brian Skalinder]

There are plenty of quality DC-powered preamps out there - what exactly are your requirements, sonic preferences, and budget?  Maybe someone here can recommend an alternative.

[Tye]

Are these comparable to Ac powered preamps?(how many hours can they run?)
 I'm looking for something with both xlr and 1/4" jacks 48V phantom power to the mics dual chanel if possible. I am running 1 sterreo mic right now (Sony EcmMS907) into the 1/4" but would like to upgrade soon > two mics (ADK?) with XLR connections , compact is good too. I'm not partial to anything yet any suggestions are appreciated. I dont want to spend hundreds of $ right now but would like to get something I can expand with.
                              Thanks for your help

[mirth]

Surpised Brian hasn't directed you this way already....

First thread, Archival Information board:
http://www.taperssection.com/yabbse/index.php?board=14;action=display;threadid=4237

[Tye]

Thanks mirth that cleared up alot of questions for me!

[chase]

stay away from AC powered pre's.  the problem from what i have gathered is that using an DC>AC convertor can actually make the noise in the preamp rise because of the different natures of the waves and the fact that most power invertors aren't that good.  it has something to do with converting AC current with is similar to a sine wave to DC current which is linear i believe.  

[BCostigan]

Looks like I learned something here......I assumed all wall warts converted AC to DC...never realized there were AC to AC (transforming) wall warts!!!    

[leegeddy]

Looks like I learned something here......I assumed all wall warts converted AC to DC...never realized there were AC to AC (transforming) wall warts!!!    

it's much easier to simply step down an AC voltage than to convert it to DC.  all it takes is a simple transformer circuit.  since 99.9% of wallwarts we use are AC>DC converters, it's easy to assume that wallwarts are used in that respect.

marc

[BCostigan]

Looks like I learned something here......I assumed all wall warts converted AC to DC...never realized there were AC to AC (transforming) wall warts!!!    

You'd never know I'm an electrician (in training) would ya?!   I'm used to xformers being big gompy things stepping down much higher voltages....I guess the idea of stepping down below even 24VAC never occured to me.  



it's much easier to simply step down an AC voltage than to convert it to DC.  all it takes is a simple transformer circuit.  since 99.9% of wallwarts we use are AC>DC converters, it's easy to assume that wallwarts are used in that respect.

marc

[chuckcage]

Looks like I learned something here......I assumed all wall warts converted AC to DC...never realized there were AC to AC (transforming) wall warts!!!    

I learned this the hard way with a Digitech Studio S100 effects unit.  It also uses a low voltage AC power source.  If you give it the same specs but DC, all the lights come on and it appears to work, but makes no sound.  Doh!

I ended up ordering the original supply from Digitech and I was A-OK.

Chuck