2. amps-preamps
  3. 184142-72674

I need impedance help. Rogue RH-5 to Solid State Amp.

I do not understand impedance, but I usually use the 1:10 rule when making a pairing. That has helped me get by in my ignorance.

I am in a situation where it’s a little more complicated. I can’t find much information on the output impedance of the RH-5. It seems like everything I read is about the headphone amplifier output rather than the pre-outs. It also complicates matters with the 3 Gain settings. Maybe that makes no difference?

I am currently using a Cambridge with an input impedance of 33k ohms or a Denafrips at 22k ohms, but I’d love to get an idea of what I’m actually looking for. Although my main amp is a good match with it being a tube amp made by Rogue, I want to find a good solid state amp to have nearby.

I read somewhere that the balanced outputs have a different impedance than the unbalanced.

So, what should I be looking for impedance wise. And does the gain settings change anything? Should I avoid the balanced outputs with a wrong amp pairing?

Thanks to anyone willing to help.

Nick

128x128nickrobotron
imhififan's avatar
imhififan
2,123 posts
 

The output impedance varied with both output and frequency. The unbalanced line output measured 0.5 ohm at 20kHz, 9 ohms at 1kHz, and 3.3k ohms at 20Hz, the last presumably due to a DC-blocking capacitor in series with the output. The balanced line-output impedances were twice these values, as expected.

https://www.stereophile.com/content/rogue-audio-rh-5-preamplifier-headphone-amplifier-measurements

 

nickrobotron's avatar
nickrobotron OP
24 posts
 

Thank you. Are those 3 measurements for the 3 gain settings? So I would be able to use a 22k amp on the first two gain settings? 

mulveling's avatar
mulveling
1,774 posts
 

@nickrobotron

Best to call Rogue for a chat - they’re friendly! Personally I would definitely be concerned by this bit "3.3k ohms at 20Hz" and this bit "the balanced line-output impedances were twice these values". That means 6.6K at 20Hz from the XLR outs?! That’s way WAY too high for a preamp IMO. Even if on paper it doesn’t look like a big dB loss in bass, and 20Hz seems far enough down, in my experience is you’ll be able to hear this as a leanness in sound.

And yeah, at least with prior models (Athena, Hera) the input impedance of the preamps changes with gain setting, so other stuff might change too.

Quite frankly if I had this unit I’d be tempted to try the headphone out (via adapters) as the preamp. The headphone out has VERY low output impedance. It probably makes some compromises to get that (e.g. lower quality coupling caps to achieve the low ESR), but I’d argue it’s probably less of a compromise than a 6.6K output impedance!

Also keep in mind Rogue's power amps often have a very high input impedance, 100K - 300K. That might work OK with the 6.6K, but when you use other amps...

avanti1960
1,406 posts
 

I had this preamp and it is super clear and has amazing drive and dynamics.  Specs schmecs.  

my amp at the time had 23k input impedance and sounded fantastic.  

what amps are you considering?   

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