2. amps-preamps
  3. 1400932591

Passive preamp w/Rogue Medusa and Rega DAC

All,

I have become intrigued with the concept of a passive pre. At the moment, I think my preamp is the weak link in my chain. Key system components are MacMini-Rega DAC-Acurus RL11 pre-Rogue Audio Medusa-Fritz REv 7 speakers. At this point I am not ready to shell out the cash for a good active but thought about experimenting with a passive. I have concerns whether a passive will work in my system. Here are the basic specs on the DAC and Amp:

- Rega DAC: 2v output, 600 ohm output impedance
- Rogue: 200K ohm input impedance, Input sensitivity: 1.0V RM
- Fritz speakers 89db, 4 ohm
- Cables are all 1 meter or less

My concerns are the output impedance of the DAC is high (but the input impedance of the Rogue is very high and I can' figure out if the gain on the Medusa will be sufficient to run a passive.

Given the high input impedance of the Rogue, I think it will work with the DAC but am not sure. Based on the above, does it look like there are any limiting factors that would prevent a passive from working?

Any comments are appreciated. Thanks.
sruffle
georgehifi's avatar
georgehifi
10,312 posts
 
You have great system parameters for a passive.

Your cdp at 2v has double what it takes to clip your amp at 1v.
It's output impedance will be fine into a 10k or 20 k logarithmic passive, if going the way of a potentiometer I would use something like the Dact [url]http://www.dact.com/html/attenuators.html[/url]
The input impedance of your amp at 200k is very passive friendly and your speakers are fine with mid range efficiency.

All in all you couldn't ask for much better, and you will hear your source in the cleanest, most dynamic and uncoloured possible way.

Cheers George
marqmike
847 posts
 
Good Point George and I think that would make the Lightspeed Attenuation a very good aprox. 450.00 option. That is the one I would chose if I had his equipment.
georgehifi's avatar
georgehifi
10,312 posts
 
Thank you for saying so Marqmike, I refrained from saying so, otherwise I would have had the wrath of the anti passive preamp brigade coming down on me, yet again!

Cheers George
b_limo's avatar
b_limo
2,288 posts
 
I am a happy Lightspeed owner and user :)
sruffle OP
57 posts
 
Thanks to all for the replies. I have been reading the massive LS Attenuator thread with great interest. (I will probably get to the end of it by 4th of July). I would love to try it but the only catch for me is that I need a remote control.

I think a reasonable path would be to try the cheapest passive I can find in my system. If it works and I like the nature of what I am hearing, I could then upgrade to a better passive and keep the cheaper one as a back-up. (while selling my current pre-amp).

Even if I don't like it, trying one is definitely something I should experiment with.
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