• 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.

EF86 Sound

EF86s sound different from various manufactures, same as any tube as reported by 1000s of audiophiles.
If you are expecting a Brand related answer ... not much of that. Tubes have so much spread that two tubes from same Manufacturer can be way more different than another pair from different ones. And most opinion out there is based on "samples of 1", meaning that, say, somebody pulls a Mullard from an amp, plugs a Philips in, and then posts, say, "Mullard is dark and restrained, Philips is sharp and jangly" or whatever .... and then that opinion is extrapolated to *all* Mullard and *all* Philips. Another Audiophile repeats the test, finds opposite results, posts *his* experience. Who´s right? ..... BOTH are .... just each result applies to one specific case.
My question on an audiophiles opinion about EF86s sonic signature is anything but strange.
You won´t have *one* , unanimous Audiophile answer, that´s for sure, although with a large enough sample, you may find "clusters" of people who agree on some aspect ... and violently disagree with others.
Have you ever rolled tubes?
Yes, many times. Basic difference I find is different Gain, most certainly caused by tube to tube variation of Transconductance. Notice I said Tube to Tube and not Brand to Brand, which is most inconsistent.

One aspect of Tube Preamps and Amps is that 99% of circuits is high to very high Impedance, so parasitic impedances, specially a few pF here and there ¨*do* affect circuit response, so affect "tone".

So if you have, say, a lower gain EF86 , play some Music with Volume control on a certain setting, then start "rolling tubes" and then replace it with a higher gain one, 2 things may happen:

a) you do not touch the Volume knob. Amp now sounds louder, which to most people means "better" , plus our own ears respond different.

b) you adjust Volume down to keep perceived Audio level about the same. Since you will typically have a 500k or 1M volume control, a few pF to ground on wires leading to and coming from such high impedance will cause different rolloff.

In both cases you will have a perceived Sound difference , which in a way is "caused by the tube" but which actually stems more from nonlinear ear response and/or components or layout external to it; tube response by itself is flat from DC to a few MHz .

That´s why above it´s correctly posted that "in a good design and layout" most any competent tube will have little to no influence.

FWIW about "Audiophile Opinion" you will find many such as this one, which is in a current thread:
- RC: You hear the effect of different resistor brands, cap brands etc. All have their sound. If you are in sound tuning business, lots of choices. I tried Duelund Cast, Cu and Cu-Ag, Jupiter and many more. Duelund giving you a nice midrange, but a bit fuzzy soundstage, Jupiter much more refined, transparent and natural. Mils very sparkling, but mechanical, Caddock warm, but not very dynmaic, Ohmite Gold a good compromiseetcetc.
so if you are all about *subjective* , unconfirmed, possibly biased "opinion" , you will find that too.

Sorry I can´t help you in that area.
 
I know same brand can have entirely different sound. Details like getter style, date codes, plate design, etc. I will buy a few different brands because tubes vary and my taste in sound nay be quite different than another audiophiles opinion. But, good to get some direction vs buying every brand, particular year of manufacture, etc.
 

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Joined 2008
In general sony6060 has fair point. Tubes with different mechanical construction might likely sound different. No-one ever considers the consequences of different vibrational regime. I have eliminated tubes from my phono and preamp set-up since a long time ago. SS is just better.
It's a very practical aspect and looking at how badly amplifiers are built from the mechanical point of view, inclusive expensive commercial stuff....., I would never tell someone who says he can spot a difference that he is wrong or is just illusion!
One has a to see case by case. Sometimes differences are there but the whole system is so bad that cannot be spotted. That's another scenario.
The most common mistake: spikes under audio gear. Very bad idea...
 
Sony6060,

What is the amplifier that you are using the EF86 in?
Is it a Hi Fi amp?
Is it a Guitar amp?
What stage of the amplifier is it used in?
Can you post an accurate schematic of the amplifier?
Is it a very old tube, or a brand new tube?
Are you currently experiencing bad sound from the EF86 you are using in your amp?
Describe the symptom . . . hum, distortion, apparent frequency response problem, microphonic, bad reliability/tube failure.
What signal source are you using?
What loudspeakers are you using?

Thousands of Audiophiles have thousands of different amplifiers, and thousands of different systems, and thousands of different ears, and thousands of situations, and thousands of different music tastes, and thousands of opinions.
 
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On this amp it might be needed to adjust R79 in order to have the plate at 100V during idle. Tubes has large tolerances, it's possible that selected ef86 was used by the maker. If the plate is significantly far from 100V the phase splitter will have a non-favorable working point. This might be the source of sound changes when testing different ef86 in this amp.
 
Can you post an accurate schematic of the amplifier?

Schematic of Knight KA-95, amp section only.

knight_ka_95_1920x2160.jpg
 
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It really looks like a Mullard 5-20. Except for some small differences for resistors and capacitors (also due to different output transformer) the only things that are different are the (poor) fixed bias for the EL34s instead of self-bias and the un-bypassed cathode rester if the EF86.
 
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I never played with EF86. For example I have a lot of experience with 12AX7s and my favorites in my amps are RCA 12AX7 black plate & Mullard 12AX7 long plate. I have liked lowly Sovetk 12AX7LPS only in a phase splitter.
My EF86 tubes so far. 1960 Mullard EF86 mesh plate, 1970 Mullard EF86 solid plate, Tesla EF806S (not JJ), and bidding on Telefunken EF86 chrome plate and early Valvo EF86 D getter.


I am very fussy about sound and need the large lot of EF86 to ensure I heard a few EF-86s at least for starters.
 
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