2. amps-preamps
  3. 165197-132585

Low gain preamp options

I’ve read lots of preamp suggestion threads and discussions on amp matching. I don’t know what percentage of people have digital only systems, but it seems like there is a missing niche for preamps.

Most DACs have at least a 2V output which exceeds the input sensitivity of most amps. So unlike a phono input there isn’t a real need for gain in most cases. The problem with a passive preamp is some amps don’t have high enough input impedance. Also a preamp allows longer cable runs (if needed). Then there’s the whole tube warmth or tone that some people are so fond of in taming perceived digital harshness.

I’ve read about lots of tube preamps, but even the low gain ones are still in the 10dB range. It would be nice to have a useful amount of volume adjustment instead of silent to too loud with just a wiggle.

The only unit that comes to mind that’s even close is a Schiit Saga+, but it seems like even mid-fi systems should be able to do better. Don’t get me wrong, I’m using one now. It’s great for $400, but at some point it’s going to become the weak link in my system (if it isn’t already). 

List of desired features:
<6dB gain 
<500 ohm output impedance
tubed output
at least 2 sets of outputs
balanced in/out optional

Anything out there that fits the bill?

cat_doorman
verdantaudio's avatar
verdantaudio
1,507 posts
 
So...I certain that I can have the gain customized on my Art Audio preamps.  The Conductor and Conductor Simply have adjustable gain.  The Conductor I had switched between 0dB and 25dB, the latter driven by gain for the headphone amp.  

Basically, depending on what you need explicitly, Art Audio can probably accommodate with one exception, the chassis is not large enough to support XLRs.

If you tell me what you want explicitly, I can get a quote and timing from Tom.  
georgehifi's avatar
georgehifi
10,312 posts
 
Most DACs have at least a 2V output which exceeds the input sensitivity of most amps.
So unlike a phono input there isn’t a real need for gain in most cases.
There’s many phono stages now that have 60db of gain, so no extra gain needed with them either.

The problem with a passive preamp is some amps don’t have high enough input impedance.
This is true, especially with Class-D, the industry standard was 47k or 50k input impedance for amps, but some Class-D’s are a silly 2kohm!! even 1kohm!!! input impedance, not good with passives and most tube preamps!!!.
You should have 1:10 ratio or more, output to input impedance, to be matched.
EG: If you have a 10k passive it will be at worst position 2.7k output impedance, the lowest amp input impedance "should" be 27kohm or higher, no damage will occur if it’s not, say 1:5 ratio or even 1:1 just cuts the volume down lower and becomes even more of a voltage divider.

Cheers George
tablejockey
3,958 posts
 
This  polarizing brand in threads, appeared to have checked of all of your requirements, but I see it does have 10db gain. So if 4dbs extra  doesn't cut it-nevermind(as Emily Latella would say)
https://www.primaluna-usa.com/primaluna-evo-400r-tube-preamplifier

all tube(including rectifier-dual mono)
even lower output impedance
balanced in/out(unknown if it's wired as "real balanced or faux, as some) 
2 sets of outputs

cat_doorman OP
237 posts
 
@verdantaudio it’s premature to start quoting custom equipment. I’m still trying to see what standard units are available.

@tablejockey the recent thread on the EVO400 volume control did give me some concern and prompted this thread. Previously I figured I’d be okay with anything under 12dB of gain, but I’m starting to have doubts, especially if I go with even more efficient speakers (>100dB).
armstrod
617 posts
 
How about something like this:

https://www.decware.com/newsite/zbox.htm

Steve might be able to do it with two outputs.
More to discover