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What advantages are there to using a preamplifier?

post #1 of 6
2/20/11 at 1:07pm
Thread Starter 

Howdy folks,

 

I've been looking for a DIY amp for my grados, and I found the a20 amplifier from AMB. I'm pretty interested in this amp because of it's double function as a preamp. I'm a bit confused about preamps, though. I've read through several articles, but they all spoke of preamps as an outdated technology. 

 

I'm not asking specifically about this preamp, more of a general purpose of preamps. Is there an advantage to controlling the volume from the a20 instead of my Crack amp? Why the hell are preamps still around?

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post #2 of 6
2/20/11 at 4:55pm
Thread Starter 

yeah, nevermind. I did a search for preamp and 1001 threads came up (instead of searching for "pre amplifier"). 

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post #3 of 6
2/20/11 at 5:00pm

You really only need a preamp if your power amp doesn't have its own volume control.  That pretty much never happens with headphones though.

 

When powering speakers you'll find there are still some old school stereo amps with no integrated volume control and monoblocks pretty much require some sort of preamp.

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post #4 of 6
2/20/11 at 5:12pm
Thread Starter 

Yeah, I figured as much. I need a way to select inputs and outputs, and I need a grado amplifier, so I figured I'd kill two birds with one stone. I could always take the pot off of the Crack amp I'm waiting on and use the preamp's volume control.

 

I am still thinking about the whole thing. I need to do more research, though.

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post #5 of 6
2/20/11 at 5:20pm

You could make a transformer box for your Crack like I did.  It worked pretty well with my SR325is when I had them, but it doesn't work to well with my T50RPs.  I copied the design that nikongod posted in the Crack thread.

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post #6 of 6
2/21/11 at 4:08pm

There are passive Pre-amplifier (i.e Volume attenuators and a switch pots to select different sources), and Active pre-amplifier.  Back in the Old day,  Most of the sources for music are Turntable, Tape reels, and Tube tuners.  So, the majority of the pre-amplifier are judge on how great their MMC amplifier, Volume controls, and Filters, tone controls, and "analog stage amplifier".  Today, One only have digital or analog source.  So a nice passive preamp make sense.  Keep in mind that different sources output different Current, Imp. Voltage, etc...   Furthermore, different power Amplifier input stage ( I.e. RCA input) have diff. gain or Voltage ( usually 0.5 mv- 2 mv).  so a nice preamp feeding the power amp at proper gain or voltage, is nice, Constant, and predictable.  Don't u just hate it when different MP3 files or source sound louder than other? Like those infomercial ( they are the loudest one)  Sunday, Sunday Sunday!!!!! ONE Day Only!!!

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