Sweet sounding tubes for preamps

First, I am a relative novice when it comes to tubes. I have been using LuminX1>Benchmark LA4>Benchmark AHB2>Soundlab, which is incredible with great clarity and speed. Some times, I wouldn't mind some sweetness in the sound (?2nd harmonics), without compromising clarity. I had Don Sachs 6SN7 preamp in the chain and it sounded sweet. I see that some preamps use 12au7 tubes. What is the character of 12au7? Can it give the sweet sound of 6SN7?


The character of any tube can vary depending on the design of the amp/preamp. I have heard preamps using 12AU7s which sounded downright chilly, neutral, and warmish. Much depends on the manufacturer and its type of tube (often the same brand has multiple models and dates of production which will sound different).

I'm guessing you are aware that the 12au7 and the 6sn7 are of similar design except for pin output, but the perception seems to be that the 'warmth' attributed to the 6sn7 will follow to the 12au7. This may not be so. A good reason to use an amp with the 12au7 is that the availability of that tube both as a NOS or new production as well as cost.  No so much for the 6sn7 - NOS are hard to get, low noise ones especially and they are expensive. There are new production 6sn7 now which are reputed to be quite good (Tung sols for example) but I haven't heard one yet. If one has an amp/preamp which uses this tube I expect one could find a tube which would err on the warmer side, but not so much as a preamp designed around a 6sn7.


You ask a great question… because your components are known to be very detailed and analytical. I would recommend going to the root of the issue. I would swap out your preamp for a musical / natural sounding one… I recommend an Audio Research (both detailed and natural sounding)or Conrad Johnson (more musical)… or VAC. These are musical and natural sounding first and detailed oriented second.

Then I would swap out the amp for a musical / natural one. Pass XA series, or Audio Research (my preference… see my profile), or CJ.

The issue is that a number of companies focus on details at all costs. It sounds like you have realized the issue with that… sterile sound. The way around this is to get components that are designed to communicate natural sounding music. You can fiddle all you want with tubes and not get around the design parameters.

It’s definitely subjective, and tube rolling is a real thing, soooo consider the source you buy from and their return policy.

I’m 75, been happy with many 12ax/12au units. Lately I am finding a preference for 6sn7 and 6sl7, mine and two friends preamps. Another friend, bit older than me, needing a new to him preamp also had 12ax/12au units, after hearing two 6sln/6sn7 preamps here is only considering 6__ preamps.


I blew one 6sn7, had a random used spare in my collection, sounded great like the original ones (Cayin Branded, made by ???)

but, I wanted a matched pair, keep the two unmatched as spares. I like spares on hand. Always have music while you have less pressure while researching ’new replacements’.

Hated the sound of the matched pair I ordered from Brent Jesse.


Someone else might have loved them.

He had me break them in for 60 hrs (simply leave on, no signal needed). Then decide.

I still didn’t like them. He let me return them for full refund, I selected a different matched pair, half the price, sounded just like the much preferred Cayins.

Cost me extra shipping, but lower cost tubes saved the day.

My friend just had a deHavilland preamp built. Not this unit, but her site:


She sent new tubes, a set of slightly used ones, and an alternate rectifier tube.

We hooked it up, loved it, messed about, slight differences: surprisingly to me was that the rectifier tube made the biggest difference, the alternate preferred.

IOW, you never know which and what, so buy from a source that takes returns.

Now, my oft repeated advice: get thee a simple tube tester. Eventually, problems will occur, you won’t know if it’s this or that, and possibly, who knows, maybe a tube ...

You have the tester for the rest of your life. Check new matched sets you buy, check them all annually, check when some sort of problem occurs, find or rule out tubes as the problem source, don’t be guessing, hopping about like a cricket on a hot surface, know what is what

I just found this one, I have the 157, gave my friend a 257, here’s one, good price, seller says make an offer.


btw, Reverb favors the buyer if problems occur, they helped me very quickly get a full refund on a unit damaged in shipping.

@elliottbnewcombjr What was the alternate rectifier that you and your friend preferred in the UltraVerve? I have an Ultraverve and am using a 5AW4 rectifier as recommended by Kara. Was the alternate a different brand of the 5AW4 or a different type of rectifier altogether? Or was it not an Ultraverve that she built your friend. Thanks!



My memory sucks, turns out it was his phono stage we were testing.

he is out of town working, will get the answer in a few days.

Kara did send him some alternate tubes, I got the units confused.

Take a look at an Atma-Sphere MP3.  Uses 2ea 12AU7 and 6NS7's in the line stage. I have one and use GE NOS tubes in both positions.  Its a wonderful preamp that will pair up nicely with many different amps, particularly balanced amps.



my friends responses:

"Kara (dehaviland preamp) sent one or two replacement tubes. But not the rectifier, and I have never swapped it on the dehavilland.  
We played with the rectifiers at your house on the phono stage.  You’re referencing the current hagerman product.  The one I have is a legacy / discontinued model that has a different tube layout….. but with the rectifier you are recalling we compared


the two rectifiers in the Hagerman Cornet Phono Stage that we played with were Sylvania 5Y3G B8M and an RCA 5U4GB. We preferred the RCA slightly