2. amps-preamps
  3. 131822-10803

Low output gain amplifier for ZU 101db Efficient speakers

I am thrilled with my new Rogue RP-5 preamp. However, like I mentioned before, the tube Hiss is really loud (I can hear back of room). It’s a smooth, non noisy hiss. I chatted with Rogue and they are sending replacement tubes but guess it’s due to my Nuforce STA200 amp with output gain of 34db. I was told that was quite high for having such efficient speakers. Rogue told me they test their equipment on high efficiency Klipsch speakers and the RP5 is quiet.

Anyway, I have attenuators coming today to help until I now find a power amp. I would love to have an Atma-Spere amp, however, they are too pricey for my budget (even used). Maybe a used Firstwatt f3 or these Quicksilver monoblock amps that are made for high efficient speakers http://quicksilveraudio.com/products/horn-mono/

The lower priced Decware amps look nice, plus they have gain settings.

For those who own high efficiency speakers with a tube pre, any other options? I really hate to switch out the RP-5 because it has all the functions available on the remote and it sounds great.


aberyclark
kosst_amojan
2,095 posts
 
ALL of Nelson's pre-amps are active in that they use transistors to buffer the output at the very least. That doesn't mean they have gain though. Nelson likes to use active buffers downstream of the volume control in order to avoid response variations going into the amp produced by a volume control who's impedance is directly seen by the power amp. Some of his amps have very low input impedances. 
georgehifi's avatar
georgehifi
4,966 posts
 
Some of his amps have very low input impedances.

Yes granted, this is the reason why an active pre is needed, if they were >50kohm then a low impedance active pre is not needed, remember the Industry Standard for input impedance was 47kohm or higher, but sometimes if the input stage is bi-polar this not achievable, but it is with fet input, then it’s up to the designer to make it so.

Classic example of a high end poweramp here in Australia having only 1kohm input impedance, only their own preamp with 10ohm output impedance would drive it, all others especially tube sounded like crap, so no need to say they also sold many premaps with that poweramp.
But here the crux, inside that poweramp was a secrete link that when pulled made it 68kohm input impedance, which I exposed online, then owners were free to use all different preamps with it including passive. It’s called shady marketing, good if you get away with it as it makes sales for their preamps.

Cheers George
seanheis1
359 posts
 
Of course he did, that’s one of his bread and butter items, he’s not going to shoot himself and his company in the foot, left himself an "out" by saying "an unexplained phenomenon" BTW Where is this quote?
It was a video interview. When pressed further he basically said that he doesn’t design preamps and that they are a completely different animal. He said to talk to the Pass Labs preamp designer and gave his name. 

kosst_amojan
2,095 posts
 
Wayne Colburn. He speaks with Pass at Burning Amp. They both have a bunch of videos on YouTube. Just search for Burning Amp and you'll get schooled by the masters. 
aberyclark OP
594 posts
 
I wonder if a company could manufacture a pre with a switch to change gain settings. I know I can change phono gain on my RP-5
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