2. amps-preamps
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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
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
610 posts
 
How about something like this:

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

Steve might be able to do it with two outputs.
terlenka
8 posts
 
Van Alstine's tube preamp might be close to what you're seeking with a "low gain" toggle�. One review gives the standard gain as 20dB, but they don't say what it is with the low gain in use. Output impedance is either 560 or 600, so a bit above your desired specs.

https://avahifi.com/collections/preamplifiers/products/fet-valve-cf-slr-preamplifier

daledeee1's avatar
daledeee1
563 posts
 
I just went through this with my system.  I was running direct from DAC to amp but the digital volume was unpredictable and appears to "bit strip" in some cases.  It does not sound right unless you turn it up.  I also can get quite loud volume without the preamp.  So this leads me to believe a passive will work.  My amp has 50 kohms input resistance.

I talked to Roy Mottram at tubes4hifi.  We are going to try a buffered passive preamp.  It will be one of his stock preamps without the gain tubes.  I can run volume only or tube buffer and if that doesn't work right we can add a small amount of gain.  He also sells a Chinese preamp that has 6 dB of gain for $500.  The one I am getting is a custom SP12.  I will be receiving it next week. 

Regardless  there are several vendors mentioned that can do this.  PS  Decware is 6 months out, last I knew.   I am getting mine in about a month. 
georgehifi's avatar
georgehifi
10,312 posts
 
I also can get quite loud volume without the preamp.
If it's loud enough you don't need more gain.

I talked to Roy Mottram at tubes4hifi. We are going to try a buffered passive preamp.
No need, you have 50kohm input impedance on your amp, a $49 Schiit Sys will do the job perfectly.
And without any distortions/colorations the buffered one will introduce (and it’s probably just an opamamp buffer)

Cheers George
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