Author Topic: 13EM7/6EM7 - cool valve  (Read 506 times)

Offline El Sid

13EM7/6EM7 - cool valve
« on: June 25, 2018, 11:07:08 PM »
I'm sure there are other valves that do the same thing, but I came across the 13EM7 twin triode, and thought it is pretty cool (6EM7 is the same thing with 6V heaters). It was originally intended for use as a vertical deflection oscillator and amplifier in TVs. The first section is a high-mu amplifier (μ=65), and the second low mu (5.5) but with 10W max plate dissipation. This makes it ideal for use as a one-valve amp - see the Miniblok and 6EM7 SET Vertical Amplifier. Circuit diagrams below. Has anyone used this valve? And would this be suitable for a headphone amp, not needing an OPT?




Offline fdlsys

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Re: 13EM7/6EM7 - cool valve
« Reply #1 on: June 26, 2018, 01:52:01 AM »
PCL86, quite common.
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Offline Mars

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Re: 13EM7/6EM7 - cool valve
« Reply #2 on: June 26, 2018, 12:41:30 PM »
Interesting El Sid. I recently came across another option for OTL headamp design using the EL86:



...but you need those 800 ohms head phones!

The P/ECL86 I would use as a push-pull amplifier (using two tubes).
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Offline Michon

Re: 13EM7/6EM7 - cool valve
« Reply #3 on: June 26, 2018, 01:03:35 PM »
I have a single ended ECL86 amplifier here that I like the sound of.


That OTL design using the EL86 interests me. I enjoyed the results that I got using one of the Little Dot OTL amps with a HD 600. Would the above circuit also work for lower impedance headphones like the HD 600 which is 300 Ω?

Offline gavinbirss

Re: 13EM7/6EM7 - cool valve
« Reply #4 on: June 26, 2018, 01:24:48 PM »
I have a single ended ECL86 amplifier here that I like the sound of.


That OTL design using the EL86 interests me. I enjoyed the results that I got using one of the Little Dot OTL amps with a HD 600. Would the above circuit also work for lower impedance headphones like the HD 600 which is 300 Ω?

I have had poor results with a PCL86/ECL86 amplifier  that was transformer coupled powering headphones. The particular circuit was far to noisy for headphone use.

Offline Steerpike

Re: 13EM7/6EM7 - cool valve
« Reply #5 on: June 27, 2018, 12:54:02 AM »
That OTL design using the EL86 interests me. I enjoyed the results that I got using one of the Little Dot OTL amps with a HD 600. Would the above circuit also work for lower impedance headphones like the HD 600 which is 300 Ω?

That circuit (or one of its many minor variations used by Philips) can put out about 15W, so you can easily pad the output with resistors to make it 'see'  800Ω, without reducing volume to an unusable level. Such padding will also improve signal to noise ratio.

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Re: 13EM7/6EM7 - cool valve
« Reply #6 on: June 27, 2018, 06:00:14 AM »
Can indeed be used for a very nice headphone amp. I have a 25kg beast of a beaut that was custom built around the 6EM7 by Mr Valve Wim Bouwman and Alan Hobkirk. It was a cost no object attempt at building the best headphone amp possible. BOM cost at the time was something obscene like R20 000 and included dual all valve power supplies, a dozen or so chokes, DACT stepped attenuator and the finest caps known to man. It was passed on from Gerald to Rodney (he had it for many years and said it was the best he ever heard), Kent, MarkC and then me. Will try to find the old posts including some pics Rodney put up.
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Re: 13EM7/6EM7 - cool valve
« Reply #7 on: June 27, 2018, 06:07:03 AM »
"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass