Best 12AU7 Type Tubes for a Preamp

@lowrider57 

After using the stock tubes, what kind of change do you want

Actually, there is nothing "wrong" with how it sounds now.  The sound is clean, clear, and there is no noise I can hear over what I get using the internal SS opamp output stage in the Hatter The Big Preamp.  Dynamics are good, as is the bass, but I don't typically split hairs over bass since I have dual subs so I can mostly adjust the sound of the bass as needed.  If anything, I wouldn't mind a bit more tonal density in the midrange through upper bass, but not at the expense of clarity.  I am also curious whether I will hear any spatial differences with NOS tubes, like greater perceived dimensionality.

I have been comparing the stock JAN PHILIPS ECC82 (12AU7/5963) tubes with reissue/new Mullard ECC92 tubes and have a slight preference for the Mullards.   I have used different tubes in the past in preamps by Lamm, NAT, Lector, BAT, and others.  In preamps using 6dj8/6922 type tubes, I gravitated to the Amperex 6922 PQ white label or Amperex 7308/E188CC white label.  I cannot remember which brands/vintage of 12au7 tubes I have used previously.

@mitch2

If anything, I wouldn’t mind a bit more tonal density in the midrange through upper bass, but not at the expense of clarity. I am also curious whether I will hear any spatial differences with NOS tubes, like greater perceived dimensionality.

From this description I would recommend Amperex. But you’ve tried one of the best tubes out there, Amperex PQ 7308. It presents lush mids smooth highs, and a 3D soundstage. Since you like the new production Mullards, it seems as though you don’t want extended highs since these are rolled off on top. I suggest trying NOS Mullard long plates with either square or round getter. If not available, Mullard box plates CV4003. Brimar is another brand from the UK, same time period, that have more clarity, are less warm with a good soundstage. I've seen box plates CV4003 for sale.

NOS Mullards don’t have extended highs like Amperex or Bugle Boys, but have more realistic highs than new production. They’re also more detailed, have a lush midrange, and 3D soundstage which can be holographic in the right preamp. The problem is price and availability. After the shortage of Russian tubes this past year, inventories of US and European tubes have been exhausted, so prices are very high. What I’ve been doing is buying slightly used tubes that test as NOS. Mullards, Amperex, Telefunken will still fetch a premium, but if they are ANOS (almost or about NOS) they could last years in a preamp. Brent Jessee would be the first dealer I would contact. Andy at Vintage Tube would have the best stock, but there’s a 6 week wait at this time. Use Google to check out prices. Maybe others can suggest some trusted dealers.

@holmz 

Brent Jessee has a detailed description of NOS brands and their sonics.

@lowrider57 - You are correct about Andy's availability.  I went to contact him this morning and found this message on his website:

Notice: Due to extreme demand, I am only answering the phone on Fridays and I am running about 2-3 months behind on filling orders.

I tried calling anyway and received a busy signal.  Even if I were able to speak with him, I am not patient enough to wait 2-3 months for delivery of two tubes.  However, I did also find the following message on Andy's website so at least there will be a future solution for people who want a faster turn-around.

Online ordering of select tubes is coming soon and those orders will be shipped within 2 days.

In the meantime, I will try contacting Brent Jessee or will look around at some other vendors. 

Interestingly, I was looking in the drawer where I used to keep tubes and found four matched, measured, and unused NOS Amperex JAN 7308 tubes that I no longer have any use for.  I cannot remember the preamp I had planned to use them in so I was surprised to find I still have them.  Some surprises are better than others!

There is an ebay seller with over 1,500 sales at 100% positive feedback who has several pairs of strong measuring Amperex 7316 tubes at what I would consider reasonable pricing (less than $200 each).  I found two pairs and emailed the seller for advice on selection.