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DHT driver for triode wired SE EL84, 6V6 or EL34

Thanks for the further explanation, guys.

So does anyone know of any other output tubes that are relatively easy to drive? The 6V6, 6BQ5, 7591 and 6N6G (and their electrical equivalents) have been mentioned. Are there some others?

I'm not sure if a strict definition of "easy" is required but, in general, I'm thinking of the various DHTs that have been discussed previously in the thread as input tubes.

Edit: Looks like the EL12n that Andy has been using qualifies, although it's not a common tube outside of Europe.

https://tube-data.com/sheets/082/e/EL12N.pdf
 
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FlaCharlie: 6BQ5, 6N6G, 7591 and it’s equivalent the 7868, and the EL12N will work, but the 6V6 is going to be very marginal with a normal 2 volt output source. My amp has nine pin and octal sockets in parallel, so I can put either 6BQ5 or 6V6 into the amp, but the 6V6 doesn’t provide enough gain for anywhere near full volume with a 2 volt source. It will work in my application as a treble amp because my electronic crossover can provide the proper drive voltage to fully flog the 6V6.

In terms of sound quality, EL84 sounds better than 6V6, but the best sounding tube that I have put into the amp is actually the 6P15P-EV, a Russian close equivalent to the SV83. This tube type sounds the best so far, and has a similar amplification factor to a 6BQ5.
 
Decware has been using them in their SE84 amps for years. They really are exceptional sounding tubes. They are cheap too. I just ordered a 50 piece box of the 6P15P-ER, a version rated for 10000 hours, from eBay for $145 USD. Other than a lower G2 rating, they pretty much interchangeable with EL84. Also, the suppressor grid and cathode are not tied together on 6P15P tubes, as is the case with EL34s. Decware has a modification to their amps that ties the suppressor grid and cathode together with a .1 uF film cap with these two tubes. It’s called the Hazen Mod, and is interesting to check out if you are not familiar with it.
 
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It's the contrary! Plate and g2 rating for the 6P15P are 330V. Not to be confused with the Svetlana SV83....

https://frank.pocnet.net/sheets/113/6/6P15P.pdf

That’s good news, and not what I remember reading. That said, the above is not a data sheet for the 6P15P-EV. I can’t find a data sheet for the 6P15P-EV or 6P15P-ER (EB and EP). There are differences in the ratings of 6P14P, 6P14P-V and 6P14P-EV that may also be mirrored in the 6P15P tubes. Have a look at the attached screen shot. Could this indicate that the EV version of the 6P15P has a higher plate voltage limit or other different specs?
 

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That’s good news, and not what I remember reading. That said, the above is not a data sheet for the 6P15P-EV. I can’t find a data sheet for the 6P15P-EV or 6P15P-ER (EB and EP). There are differences in the ratings of 6P14P, 6P14P-V and 6P14P-EV that may also be mirrored in the 6P15P tubes. Have a look at the attached screen shot. Could this indicate that the EV version of the 6P15P has a higher plate voltage limit or other different specs?

EV and ER have the same electrical specs at the very least. Possible 10% more plate dissipation for EV variant. The main difference is lifetime. Same as 6P14P, I think.
 
There are differences in the ratings of 6P14P, 6P14P-V and 6P14P-EV that may also be mirrored in the 6P15P tubes.

That table however is a bit misleading. The higher plate voltage than 300V is conditional for all variants. Only recommended for plate dissipation equal to or less than 8W. Instead the 330V for the 6P15P are not conditional.
To be honest, I played with a friend of mines around a guitar amp with the 6P14P-EV when they were very cheap a few years ago. Plate voltage 450V, g2=350V and biased for approx. 30mA. If played hard the tubes would not survive long.....

A HiFi amp will likely not stress the tubes like a guitar amp but lifespan will be greatly reduced. I would not go beyond 350V for plate voltage. This works fine...I even do it with the PCL86 in triode mode and have had zero reliability issues so far (345V/23-24mA, from last measurement, with fixed bias into 8K I get 2W+ at 5% THD....poor man 45 amplifier...on paper, really nice in reality). The current PCL86's I am using were made by EI but I have had success even with the cheapest PCL86, the Polamp (Polish Philips factory). Only real difference is that Polamp PCL86's tend to have lower gm and give a bit less power for the same THD.
 
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