2. amps-preamps
  3. 1325552222

Active or passive preamp

Hey guys,

I need some advise as to whether I should go active or passive on a preamp. Although I have several digital sources, I'm running all of them through an Emotiva XDA-1. It's nominal voltage output is 1v with a max of 7v. Its output impedance is 1K ohms.

My amp is an Aragon 2004, with an input sensitivity of 150mv for 1 watt. Its input impedance is 22K ohms.

Although I've been doing as much reading up as I can, I'm still not sure that these components will be a good match with a passive preamp.

What do you guys think?

Thanks.
tonyangel

Showing 2 responses by intactaudio

intactaudio
293 posts
 
Hey,

The Z-out is a function of three things. Source impedance driving the inductive volume control, step down ratio and DCR of the coils.

In the case of an autoformer with a 50 ohm DCR the Zout is as follows. (numbers quickly read of a log graph so are approximate)

1K @ 0dB
505 @ -3dB
252 @ -6dB
76 @ -12dB
22 @ -18dB
8.2 @ -24dB
2.8 @ -30dB
1.5 @ -36dB
.58 @ -42dB

The input impedance at low frequencies is the parallel combo of the primary inductance and the reflected load. and in the case of the autoformer above it will be down 0.1dB @ 11hz

dave
intactaudio
293 posts
 
Hey,

John still sells the naked units and OEM's them to Experience Music, Purity Audio and a few other high end manufacturers have proprietary versions. Artemis Labs, Aprilsound and Thomas Mayer all use a version of the autoformers in their top level designs and Silbatone has them wound with high purity silver.

We are working with Paul at Front Panel Express to offer up a plug and play chassis for both the remote and manual autoformer modules To fill the gap John left when he stopped selling finished units and Jeffrey Jackson and Myself offer finished units to match the aesthetic of our soon to be released Emia phono stage.

dave
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