• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Those Magnificent Television Tubes

Isn't this nice...I don't see much *non-existing, linearity* here...

EL509-Triode.gif


JJEL509 as tetrode

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That is interesting, exactly how a debate about transistor amps has been going. 5 watts is exactly where we thought we would win most. The stricter transistor designers like class AB to be pure B. The idea being gain doubling increases distortion if extra bias used. I find regardless of maths offered pure B is impossible as it always drifts. 5 watts seems to be a universal point where most people are going into ear distortion. Apparently regardless of room size speakers seem to be chosen to favour 5 watts at normal listening levels. No continuous effort seeking that , just how people choose. 82 dB / watt small room 105 db / watt large room. Douglas Self favoring 20 watts in A and the rest in C ( class G ).


How does one most efficiently choose class AB for a valve amp? All my designs are SE so never tried it. I had a Siemens 2 x EL 34 cinema amp 100 watts class A I was told ( 800 V ). 13 % THD at 100 watt 1.3 % 10 watt with 9 dB feedback. I often wondered if it was class AB? If so I didn't see anything different. My brother who isn't with us now said class A2. I plan to build a PP with SE driver in long-tail pair output ( you guys call it something different, it gives 70 V rms so no problems as I need 56 V rms if SE drive + PP 34's which I have tried , for a 211 I plan to build one day using LTP 34's as dummy load ). Strikes me I should learn AB at the same time. I have 43% UL taps if I choose for EL 34.

I asked about distortion of the driver as often it is higher than expected. No problem but makes a mockery of people who disdain pre-distortion. Inverting the phase of a stage will give cancellation if wanted or not. In the design I just made I manage to run an oversize driver at 20% it's maximum and still have bags of drive. I took a bucket of very worn out valves and did tests. Best to worse 1 % to 1.5% THD with similar curves. Instead of being a test I realized it was a good use for worn out valves. Some of my worn-out's would be prized if full emission. I was very strongly told not to do this, I had to be certain. It seems to me inverse curves are highly reliable if the limits of emission are not used. Eventually I found pentode and triode/UL output to invert beautifully. Hiraga style harmonics being the goal. I would call this input to output UL. As a bonus distortion was 1/4 and gain raised by 4 . As a pentode was not driving the load that was the ideal way. I used 82% UL ( triode end ) as it seemed to give a slight gain boost with no distortion change I could measure. There was by chance a tap that gave that. I have in the past disliked UL . When no loop feedback used it seems excellent. Pre-distortion is exactly like negative feedback in how it shapes the waves as they pass thorough. Obviously the conventional loop version is any curve you want. The pre- distortion is what a device gives. the Big advantage is no phase shift at HF. I also found adding loop feedback when pre-distortion used seems to have better outcomes. Conjecture says more gain available and reductions sort needing less dB's of feedback . The Hiraga harmonics seem easier to get if so. I didn't listen to that combo so have no idea if better than usual. The analyzer said it should be. This would aid transistor amp intended speakers to work that need a constant voltage source output. My amp was 600 mV in for 8 watts out. Using 12 dB of feedback would still be OK for many preamps. Distortion would drop to 0.25 % and damping factor to > 10 if my maths are right. Not bad for 2 valves. This was after rejecting a RH 34 amp as it seemed to me not to meet it's implied spec. I was told by someone 5% THD wasn't a problem. It was for me. RH implies less than 2%. I could not get that. I was even using a Sowter transformer loaned to me so it had the best of everything to make it work, also it needed almost 3 vrms to hit full power. That's a voltage gain of about 3 when I had about 14.
 
I had a Siemens 2 x EL 34 cinema amp 100 watts class A I was told ( 800 V ). 13 % THD at 100 watt 1.3 % 10 watt with 9 dB feedback. I often wondered if it was class AB? If so I didn't see anything different. My brother who isn't with us now said class A2.

Well, this amp seems to coincide with the application given here, page 3, last coloumn. Interstingly, it ist called class B in this sheet (and all others).

Best regards!
 
That's an interesting triode. Data sheet here. It would seem the same sort of extraordinary precautions against parasitic oscillation employed with the 6С45П (6s45p) and the 5842 are in order, when the EC86/PC86 is wired common cathode.
Talking Alternatives....
Love to see who will agree. I could not believe the awesome sound the Raytheon or New Western Electric type JW 5755 / 420a tubes. THey are the BEST sounding 12AX7 ECC83 replacement. Big deal you might have to change a few wires on your socket or get an adapter. They sound exactly the same as a Blackburn Mullard ECC83 At 15% The cost.
Andrew.
 
Type JW 5755 / 420A Raytheon / New Western Electric

Amazing replacement for Mullard Ecc83
/ 12ax7
Everyone That I had listen to the 5755 tubes in place of the Mullard old stock 12ax7 was blown away. What an awesome tube.
Best sounding tubes. All you have to do is switch a few wires on the tube socket and for 15.00 ea. you will get the very best sounding 12ax7.
I Rather pay 15.00 bucks then over 100.00 ea. for the best sounding 12ax7
This is one of the best discoveries ever.
I bought some Raytheon 5755 tubes and replaced all my 12ax7 vintage mullard tubes not only saved over 500.00 I Even think they sound better.
This is cool
Andrew
I bought some yellow branded Raytheon 5755 tubes think they are best.
 
Many audio valves are found in TV's doing interesting work. My brother pointed out to me the I was probably mistaken about them being designed for audio. PCL86 is seen in all sorts of places. I think I counted about 4 in a TV of which one was audio.

12BH7A seems a nice substitutes for ECC82 where I have tried it. I never bothered to look at specs as my ears just liked it and it had a similar cathode current. As someone who knows transistors better I tend to think of all valves as high distortion devices. If one suits me better I am liberated from asking how unalike it might be. Safety checks aside it works or doesn't work.

As there is a good chance a TV will have used a valve I suspect any will be loosely speaking TV types. 7199 comes to mind. I doubt it was used in TV although it should work. As far as I know it is a special of TV origin ? I seem to remember RCA had circuits to promote 7199 that look almost exactly like the Dynaco. The Rogers Cadet had a variant of PCL86 where two devices form a Quad like power amp except triode input.
 
PCL86 is seen in all sorts of places. I think I counted about 4 in a TV of which one was audio.

Are you sure? The PCL86 was developed, better to say derived from the ECL86, as a distinct audio tube. It's precedessor was the PCL82, a more universal tube that could also be found as the frame deflection amplifier, followed here by the PCL85.

In some very early continetal TV sets there could indeed be found up to four identical valves (ECL80) in four very different applications: Sync separator, sweep generator, AF and frame deflection amplifiers.

Best regards!
 
RELIABILITY CONTROLLED Raytheon 5755

These are the best sounding tubes. I was able to find some for 15.00 each.
In my opinion These sound better then the Mullard ecc83. The 5755 tube is 10,000 hours with no noise. I could not here any noise what so ever. Yet could here the birds and other sounds I could not here with the 12ax7 Mullards I was using.
I will suggest the Ratheon RELIABILITY CONTROLLED ck 5755 or 5755 as a direct replacement for the Mullard 12ax7 ecc83. All you would have to do is rewire the tube socket or simply buy the 12ax7 to 5755 tube socket adapter.
See the 5755 / 420a tube was designed for telephone communications. These tubes are super durable and were designed to produce an excellent sound to boost communication from all over the world. I have been investigating tubes for many decades. Please let me know if anyone has a tube question. It is my passion.
 
Are you sure? The PCL86 was developed, better to say derived from the ECL86, as a distinct audio tube. It's precedessor was the PCL82, a more universal tube that could also be found as the frame deflection amplifier, followed here by the PCL85.

In some very early continetal TV sets there could indeed be found up to four identical valves (ECL80) in four very different applications: Sync separator, sweep generator, AF and frame deflection amplifiers.

Best regards!


As you say exactly. The point being the P series is more TV and the 86 series more audio. the point being that they are TV generics. Not quite sure what UCL series was about? ECL is lead acid battery series. I doubt any were used that way and is archaic reference to 12.6 or 6.3 V. I wonder how many valve users have tried that? My own tests of heater supplies suggest hum bucked come within 2 db of absolute hum levels on a power amp. I never tried a battery. Maybe a dB to be had? To charge a battery when the amp is sleeping would not be a complex circuit. The charger could kick in if low volts detected with a simple op amp comparator and TL431 reference. 15K + 10 K divider to the heater diode and 3K3 to the TL431 side. If using LM354 a relay can be driven. The ratios will need tweaking a bit as 6 V may be a viable voltage .
 
As you say exactly. The point being the P series is more TV and the 86 series more audio. the point being that they are TV generics. Not quite sure what UCL series was about?

Pardon me please, I can only speak of the German context: All U series valves were designed for series heating, as are the P series tubes, but, in opposite to them, for broadcast receivers. Until the 1950ies AC power grids were not quite common here, as also existed DC supplies. Also there were many different power grid voltages. So most radio manufacturers produced devices for both AC and DC use, and for them all U series tubes were needed.

P series tubes were developed, or derived from E or U valves, for TV applications. Their demand for 0.3 amp, in opposite to 0.1 amp for U tubes, series heating was due to the higher number of, and more powerful tubes in TV sets.

ECL is lead acid battery series. I doubt any were used that way and is archaic reference to 12.6 or 6.3 V.

The E series valves indeed primarily intended to be used in cars with 6 volts lead acid batteries. Tubes with 12.6 volts heaters resulted, at least in Germany, from WW II, here vehicels had six cell batteries much prior than those for civil use.

There are some parallels between E-, P- and U series tubes. E.g. ECL82, PCL82 and UCL82 all are the same tube, but with different heaters. BUT: PL84 and UL84 by no way are modified EL84's! Their E series correspondent ist called EL86.

List to be continued :).

Best regards!