EL36 / 6CM5 TESLA tube tubes store. TESLA EL36 / 6CM5 high power amp tube. Customers who bought this product also purchased. Class, Va, Vg2, Vg1, Ia, Ig2, Zout, Pout, THD. Line output, , , , B ( idle), , , , 36, 1, B, , , , , 38, 3,, , He offers a 6CM5/EL36 based 2 x 22 Watt Stereo Class AB1 triode amplifier, the fuss was about tube sound, while their solid-state amp’s are being repaired.
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Before continuing to read on with this text please note ek36 following: It was so totally different from my EL84 amp, comparing mono to mono. As I build a lot of valve projects requiring an audio stage the 6CM5 has been of interest, especially as I have a huge quantity of them!
This is done to get V for the screens, a voltage which, under no circumstances, may be exceeded. Ratings are similar; same top cap and pin out. With no bias and 25V on the screen, the anode was drawing 45mA at V. It’s a Maton Powerpack Studio amp. Such performance merits further investigation.
Notable is that the anode power dissipation is specified at 18W; considerably higher. For single-ended application, the EL36 linearity is problematic to say the least, and available output power is somewhat less than a 6BM8.
6P31S / 6P31C = EL36 = 6CM5 tube. Beam tetrode
Philips used them in PA amplifiers as well. A while ago I decided to spend some serious time on one of the smaller amps the model with just a pair and see if I could come up with some descent results using cheaper and or more readily available tubes! In a pentode output circuit the screen can be adequately bypassed, but in triode-connected or screen-drive circuits this is not possible. The other method is of a much higher impedance, and also tends to sag as the main HT winding drops with currant drawn.
The primary impedance of the output transformers would be something like 3.
EL36 @ The Valve Museum
The practicalities of using an audio transformer meant that a cathode follower stage would be preferred, and so a test circuit was tried. I tubs ‘probably’ as I haven’t done any actual distortion tests but only visual inspection of distortion as seen on the CRO.
I acknowledge inspiration for my design came heavily from the following web pages; http: If omitted there will be slight negative feedback from the 6CM5 cathode. If not, you will need to re-think this; possibly with a very small, few milliamps 40 volt transformer tuve give the higher needed voltage.
An would be worthwhile trying in the circuit here as well. I have spent a lot of time on this point, and can’t argue enough to add these to every valve amplifier you make. Here is the resulting set of curves.
THE CONVERSION OF EL503 TUBE AMPLIFIERS TO USE THE EL36/6CM5/EL360 FAMILY OF TUBES
Well, firstly, in this mode it sounds a lot better than a single-ended 6V6 or EL34, and better even than a single-ended 2A3, and secondly, its low cost. This has made the filter choke redundant, and many of these have been thrown out. The main smoothing capacitors are even keeping the clipping point flat with no ringing coming over the top of the caps whatsoever!
With the road and engine noise in an open car, Hi-Fi is scarcely worth trying to attain! The 6CM5-EL36 is a good, low cost choice for an SEPP single-ended push-pull amplifier as it has a low average anode voltage and is capable of passing around mA of anode current.
Screen grid drive was a lot better, even though about 42V pp was required to drive it. The Mullard EL36 is distinguished by the absence of the top-cap; the anode is at pin 3 at the base. The reason for using DC coupling becomes apparent when we see that the grid of the 6CG7 voltage amplifier is connected to the 6CM5 cathode via an adjustable voltage divider.
I couldn’t really get good linearity with decent output power. However, having the design knowledge and winding facilities for transformers myself, it is of course convenient for me to do this.
The transformers are mediocre at best, though. This makes a nice simple power amplifier. Most CD players and modern hi-fi music sources these days have op-amp output stages which are low impedance and can also drive the transformer in unbalanced mode. What did become apparent was the less bias the 6CM5 had, the more power it would produce without distortion.
Additionally, the method of bias and voltage regulation also bears some importance for maximum power output. It is still in current manufacture Soviets and the Chinese so look around and you will find some budget priced units, I’m sure. I do however personally prefer the sound from the 6V6 and the higher output power from the 6L6. I am most grateful for John’s contribution of time, experience and knowledge as evidenced below.
However as the secondary of this only needs to make up the difference of the original power transformer HT up to volts, it actually won’t be quite that big!?
To achieve the necessary voltages just do the following: I have also not done any experimenting with them in self cathode bias mode. You may need to re-do this a couple of times as the tubes settle.
EL 36, Tube EL36; Röhre EL 36 ID, Vacuum Pentode
Pushing the EL36 family of tubes this hard may reduce their lifespan? The amp itself had only a swing of volts for the negative bias, so my first move was to change this for a volts swing through two 20 turn pots; one for each tube.
The sound is clean, accurate, detailed, emotionally involving, with the typical smooth treble and precise bass with a warm midrange. Although a plot of EL36 curves eel36 triode mode appeared reasonably linear, the EL36 was found to perform relatively poorly in a simple single-ended triode-strapped configuration, exhibiting very obviously poor linearity. The Soviet 6pi31 6P31 is a direct equivalent, and the well regarded Sveltana branded type can be purchased cheap and in quantity. This increases the sensitivity of the amplifier to 56mV rms or without the cathode bypass on the first 6CG7 triode, to mV rms.
In reality the actual power to the voice coil will be less due to transformer losses.