What is your impression of vintage Telefunken signal tubes ?

noromance, I see.

I have a VAC Avatar SE integrated, it uses three 12AU7 in the driver stage. When I asked Kevin, the designer, he recommended Brimar and Sylvania, and that's what I put in it - Sylvania long black plates from 1950s.

I thought I might try at some point Telefunken/Siemens/Valvo.

I use 12AX7 Mullard long narrow plates from late 1950s for phono and line amps, and Mullard EL34 XF2 power tubes.

Everything sounds excellent, very balanced. No need to change anything, just audiophile curiosity.

I roll 3 different NOS tube sets in my pre: tele medicals, brimar cv4003’s & Siemens nickel plates. I like all 3, but my go to are the Tele’s. Smooth, linear, clear & accurate. 

My Telefunken ECC801S do the full range well.  The clarity and detail is what sets them apart from other tubes that I have.  If they were poor in the mid and low frequencies, I wouldn't sacrifice those. 

The Siemans ECC801S are close.  Looking at ebay, a nice matched pair is getting pricey and difficult to find. 

@milpai 

I think a lot depends on system matching too?

agree that tube selection is like any other component, including cables -- should be chosen carefully to synergize with the rest of the setup to achieve the sonic attributes desired

this having been said, i have found that specific vacuum tube sonic traits remain remarkably consistent and audible in well designed gear, but is particularly noticeable in simpler (sometimes older) circuit designs that use the tube as a more essential part of the musical production (i.e. in the i/v amplification section, as opposed to in a follower/buffer application) -- so one should always thoroughly understand what each tube in a piece of gear is actually doing 

in a vac pa90c amp set for instance, the difference between an iec mitcham mullard 12ax7 in the first position input/phase splitter spot vs a heerleen amperex one is immediately audible

I have several ( read too many!) NOS testing small signal tubes; 12AX7, 5751, & 12AT7.  I’d rank them as follows:

1. Telefunken, smooth and ribbed plates.  I can’t tell much difference in the two. Clean, clear, detailed and neutral throughout frequency range, top to bottom.  The reference standard. Great for hours of non fatiguing listening.

2. Amperex Bugle Boy. Similar to the Telefunkens but with sparkle and shimmer on top end. Big, expansive sound stage. Nice wow factor.

3. Raytheon black plates. Warmer, “darker” with great mid and lower bass. Also big soundstage. My favorite for jazz and acoustic folk.

RCA black plates and GE 5 star next in line, then Sylvania black plates.Mullard and Brimar veiled and “softer” without any wow factor in my system.

Teles top technically.