[Nik]

This is what I found about the 6C45 used in my “R-10H”.

The new 6C45 Sovtek tube
“The best discover I've recently made is the new 6c45 Tube. This little monster si able to dissipate 8w, has insignificant noise and 900ohm Rp (!).
From the 1st moment I saw the specs I've recognized this will be "the new millennium tube".”

Tube mavens Sovtek are now offering their 6C45 high Mu single triode tube. Originally designed for military communications and radar for the Russian armed forces, and only previously known as an extraordinary audio amplifier to a small group of circuit hackers from the Eastern Block, the 6C45 is now available at $29.80 each. Basically, the 6C45 is a high Mu single triode with a low plate resistance and a very high transconductance. The input noise resistance is 100 ohms, very low input/output capacitance and the dissipation are nearly 8 watts which Sovtek claims makes it "an ideal candidate for pre-amp, driver and signal processing applications." Added benefits of the tube are that it is very quiet. Sovtek says that "One would have to parallel 15 dual 12AX7-type tubes (that's 30 sections) to get the noise voltage down to one single 6C45." Meanwhile the distortion products are lower than the 6922 but at 2/3 more gain (see chart below).

6C45-Pi Tube Data
Filament voltage 6.3 volts
Filament current 440 ma
Typical operating conditions
Plate current 40 ma
Plate Voltage 150 volts
Grid Voltage - 9 volts
Transconductance 45,000 umho (45 ma/V)
Mu Factor 52
Interelectrode capacitance
input 11 pf
output 1.9 pf
Maximum Ratings
Plate voltage 150
Heater/cathode voltage 100
Cathode current 52ma
Plate dissipation 7.8 watts
DC grid circuit resistance 150K ohms
Pinout:
1 Cathode
2 Grid
3 Cathode
4 Filament
5 Filament
6 Cathode
7 Anode
8 Grid
9 Cathode
Note: As with some other high gain, high transconductance tubes (such as EC88/6DL4/8255), there are multiple cathode & grid connections.

 

[MirandaX]

I think it's risky to spend a lot of money on an amp with these tubes until more is known about them. A big part of the sound of a good NOS tube comes from the purity of the metals used (tubes work on the principle of thermionic emission from metals). In the 50's and 60's phenomenally pure metals were being used by the best factories. These days Sovtek has a less-than-stellar reputation. It's hard to find anyone who prefers the sound of a Sovtek tube to even modern production from JJ/Tesla or Ei Yugo, let alone good NOS tubes.

Not to mention that if you go with a new design from one company, there aren't any alternative or NOS tubes. One of the biggest advantages of tubes is being able to roll them to get the sound that you want.

 

[Nik]

Dear MirandaX,

It seems that you are very determined to destroy my project to have the best amp for my cans… Why? As I sad, I’m not a technician but I have a lot of faith in this person that is building the “R-10H” ultimate amp, and I believe that when ready the amp will be totally right for the R-10 cans. About the Sovtek 6C45 he knows very well and he told me a lot of good things about this valve, I haven’t reasons to think that it is not good… is in his interest to build a very good amp. For me. The EAR HP-4 ( that is considered one of the best headphone amp, (and I think so too) uses the Sovtek 6SL7 GT and do not accept any change, even the same tube but different signature. I tried a lot of tubes NOS like the 5691 RCA red base, Sylvania, and others: nothing to do!! Ask to Jatinder about this argument… he tried even a very special an rare tube: Mullard, and nothing…. The technician knows very well the sound that I want and that I'm looking for, he knows very well my cans too... and for this reason he thinks to this new triode of Sovtek.

I hope you help me without criticism that do not build nothing…!!!!

All my regards
Nik

 

[MirandaX]

??? I'm not trying to "destroy" your project. You asked what people think of the new Sovtek tube and I gave you an honest answer.

Personally, I've only heard the Sovtek 6922 and EL84, but I didn't really like the sound of either in comparison with other modern tubes of the same type (NOS tubes are something special). The Sovteks were muddy and the highs were rolled off.

 

[Nik]

GOOOODDDD!!!!!!!!

Something about your system? In your profile... nothing!!!

Friendly
Nik

 

[kelly]

(Kelly breaks out an umbrella for a ringside seat to the heavyweight pissing match about to start.)

 

[carlo]

hey nik,

i'm not familiar with the tube, but it sounds interesting. the idea of low distortion is intriguing, as the 6922 (in my experience) has been the least "tubey" sounding line valve, if incredibly microphonic and (as i understand it) far from the best - ie 6h30, nuvista. did you consider other tubes as well? also, is sovtek the only manufacturer of the tube, or are there competing products and/or substituable tubes?

mirandax,

i agree that the sovtek 6922 sucks (although i think its because of a harsh glare in upper frequency, strident nature, and sounds as if the music was pushed through a cheese grater). but the sovtek lps 12ax7 is a hell of a linear tube and their current el34s are very good. the name gets drug out in the mud because its the OEM source for a lot of manufacturers of 6922 equipment, and the sovtek 6922 happens to be god awful. don't discount the rest of the line, as i understand it their 6550 is excellent.

best,
carlo.

EDIT: Nik - sorry, forgot to say, that is one gorgeous amp.

 

[Astroinvader]

Hi, haven't posted much - I'm a noob.

Don't have a tube amp, yet, but I stumbled across this Swedish site containing tubes. Sorry if this is rubbish, but I hope it's cool.

http://www.lh-musik.se/lis.htm

They even have a list with their grades for the tubes:

http://www.lh-musik.se/ski.htm

Here's a Danish site...

http://www.pyndt.dk/

 

[bootman]

Welcome to Head-Fi!
I can't read them

but I always like sites about tubes.