Need help with tube rolling.......

[Kris K]

After many years of using a ss preamp I took the plunge with a tubed preamp, the AE-3. What a difference this has done to the sound. I want to upgrade the stock Chinese tubes with a tube that could liven up the midrange and present a great lowend. The AE-3 uses 6sn7's.

I was looking at KenRad vt231's or Sylvania vt231's. Would these be a good mate? What tubes do you suggest?

Thanks, Kris

[No Disc]

kris,

Congrats on taking the plunge...

I have the AES AE3-DJH but have yet to do any tube rolling, although the previous owner had already put some nice NOS tubes in there for me.

This below information you might find helpful. It was posted to this forum before and also found in the AA archives. Mobile Homeless has commented that the provider was biased and placed the tubes he sold at the top of the list. You can compare this with the lists and descriptions available from tubeworld (www.tubeworld.com/tubes.html) and those from Brent Jesse ( http://www.audiotubes.com/6sn7.htm )

YMMV

- tb

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RE: 6SN7 Audio Performance

This is the third update on the sound performance of the vintage 6SN7 types. I want to thank all the customers who have sent me their evaluations of these tubes. Let me stress that the optimum tube for your system will depend on your equipment and how your ears judge the tube's ability to reproduce live music.

Customers with Single Ended tube amplifiers and Atma-Sphere OTL amplifiers stated that the difference in performance was easy to hear. I did find it surprising that their final tube preference was very similar.

The general consensus is that the vintage 6SN7GT types, especially the 1940sVT-231s and C Military series(basically the same construction) sounded much better than 5692s and later GTA/GTB tubes in most cases. I must add that the 5692 is a very quiet tube with excellent speed, if you have equipment where 6SN7 tubes are microphonic, a 5692 may be the best choice.

I will again caution everyone that various 6SN7 types have different voltage and plate dissipation ratings. The voltage rating refers to voltage across the tube's plate and cathode. To ensure good tube reliability you should probably run a tube at 70% or less of its maximum plate dissipation.

5692 - 275 Volts maximum & maximum 1.75 Watts per section

6SN7GT/WGT -- 300 Volts maximum & maximum 3.5 Watts per section

6SN7GTA/GTB - 450 Volts maximum & maximum 5.0 Watts per section

Using the general audio application of 250 plate volts, a bias of 8 volts results in 9ma of current and a plate dissipation of 2.25 Watts, we find:

5692 - runs 43 % over maximum rating It isnt a 10,000 hour tube when you run it this HOT!

6SN7GT - runs 64% of maximum coasting and liking it

6SN7GTA/GTB - runs 45% of maximum Hardly turned on, may outlast you.

When in doubt check with the manufacturer of your equipment. If they provide a schematic with component values and voltages, it's easy to use Ohms law to calculate the current and dissipation.

There really is no reason for manufacturers not to provide this information.

Here are the rankings. If you have anything to add, email me and I will add it to the list.

VT-231 Tung-Sol, round black plates - Clean, fast, the best in everything, wide bandwidth, great resolution. If you cant find the Music, its not the tubes fault.

VT-231 RCA, black plates, rich harmonic structure, beautiful timbre and voicing, wide soundstage

6SN7W Sylvania (Mislabeled by me as the 6SN7WGT), black plates Tied for second and came in first if your system sounds a little laid back, especially some single ended amplifiers Excellent low level detail resolution, very immediate sounding with a lot of Slam. There are three types of these tubes, two large bottle types, one has a metal ring and one smaller bottle with s smaller plate structure. The smaller one has better low level detail and the larger ones have more slam.

VT-231 Raytheon, black flat plates - like the Tungsol a little sweeter, nice balance of detail and timbre

VT-231 Ken-Rad, flat black plates - Great Bass, drive, sweet midrange, good bandwidth and

VT-231 Sylvania, black plates, wide bandwidth, well balanced, excellent sound stage and air

VT-231 National Union - good drive and great midrange, softer bass and a touch euphonic

6SN7WGT, Tung-Sol. Black Plate, brown base Sounds similar to the Tung-Sol VT-231, not as clean

6SN7WGT, Tung-Sol. Black Plate, brown base Very good bandwidth, bass, detail and soundstage,

6SN7GT, CBS/HYTRON Black Plate, quiet and musical, the best of the non-military tubes

6SN7GT, Ken-Rad, black base, bass a little tubby, but clean with great ambiance and air

6SN7GT, Sylvania Green Label, first top getter on the list, non-fatiguing, smooth, with good detail resolution and bandwidth, plus its easy to find and afford.

6SN7GT, RCA Black Plate, still a side getter, rich harmonic structure and maybe a little too sweet.

6SN7GTB, Sylvania Green Label, rich harmonic structure, good midrange, decent soundstage

6SN7GTA, General Electric Black Plate, the great driver tube? Fast, wide bandwidth, smooth sound at the expense of the of low level detail. Along with the Sylvania 6SN7GTB, a great fourth tube in Atma-Sphere amps.

6SN7WGT, Sylvania Green Label, Top Getter, silver top , very clean with great detail resolution and speed. Bass can be a little tubby and midrange a little congested.

6SN7WGTA, Sylvania black base green label, clean and fast with great drive, good bass

5692, CBS-Hytron, fast, good dynamics, lot of air and great timbre

5692, RCA Red Base, very warm sweet sound, great on voices and jazz

6SN7GTB, RCA, rich midrange, warm sound, likes being combined with other 6SN7 types, likes the Atma-Spheres

6SN7GTB, G.E, Gray plates, work horse, lacks refinement, a good tube

Its surprising how many 6SN7 types came out above those expensive 5692s.

One thing became clear based on customer feedback, combining 6SN7 types seems to work better than using all 6SN7s of the same type. With so many preamps and amps using this tube, you can end up with

Six 6SN7s per channel. It appears combining tubes like the VT-231s as voltage amplifiers and 6SN7Ws or 6SNGTA/GTBs as driver tubes you gain the strengths of all. Using one type seems to accentuate the tubes weaknesses.

Yes there are a lot of 6SN7 types not listed, many of them very good tubes. Based on my own personal experience and customer feedback, the Brimars and Mullards(except for the B65), are good tubes but do not offer the performance of the best US vintage tubes.

The currently produced tubes are about as musically satisfying as a Boom Box. I cant understand why todays manufacturers dont just copy some of the great ones. If you are out there, Russia, I will provide free samples. You did it with the 12AX7LPS, do it with the early Tung-Sol, RCA and Sylvanias.Sorry just had to stand on my soapbox for a second.

Best Regards, Dennis

Dennis Boyle, email chimera1@mail.idt.net

Chimera Laboratories - www.ChimeraLabs.com/~CL/

1414 South Akard Street

Dallas, TX 75215

TEL: 214-428-3901

FAX: 214-426-6605

[steve]

Hi Kris

although I don't have a tubed preamp (yet) I have an Assemblage SET tube amp that I have owned for about 3 years, and love it. I've rolled my 6SN7 tube, and what with Kenrad, RCA, Sylvania, Tungsol, etc. I have found that my favorite all around tube is the Sylvania 6SN7GT-VT231, and the second best is the RCA VT231 dark glass..but that's my humble opinion. Although the Tungsol seems to get the best raves, it's a little too detailed in my system (Khorns). Maybe a tube preamp will change all that..

Regards,

Steve