EL84 vs 6v6

shaunm

In an 18w single channel amp aimed at blues/jazz playing which would be your valve of choice.

I had 84's in my Laney Lionheart and loved that amp, I liked it's early break up but I didn't think the mid's were that pronounced.

I had 6v6's in my two rock Exo and loved the cleans and the way that it would break up if pushed hard. I did find it quite dark though and needed to dial back the bass nearly all the way and have the treble on nearly full or it was overpoweringly dark sounding.

6l6's and EL34's are not on the menu.

Which do you prefer the 6v6's or EL84's and why?

(Sounds like the most geeky blind date question ever asked)

ecc83

Can't give you a preference, never tested the switch but the EL84 has a much higher gm than the 6V6 and so the latter will need about 3 times the drive voltage compared to the 9 pinner. This means the PI  must work that much harder so you are probably not just "hearing" the changes wrought by the V6.

FYI. I was told (by the designer!) that the HT-20 can take 6V6 (check bias and do the sums) . I have a 20 and some V 6's, just never got around!

Are Langrex (?) still doing 6v6 at a fiver?

Dave.

mfin

The original question is comparing the valves as if they define the characteristics of those two amps, whereas the power valves are far from being a main defining factor of the sound of an amp, you've got to look at the whole circuit design.

shaunm

True and a good point. That's why I was looking for a bit of advice from people that have had them in a few amps or maybe have A/B'd them in the same amp.

My experience of them both is limited although in one way or another I've had them in an amp in my house for the last 10 years.

I've had a look on line and I keep coming up with Vox comparisons for the EL84's however I know Marshall use them in smaller powered heads so there must be more to them than Vox.

english_bob

I was wondering the same thing recently, and found this video on youtube:

https://www.youtube.com/watch?v=aFtvozIK7zY

It's not exactly jazz and blues orientated but it does give some idea of how the two valves sound in an otherwise identical amplifier. The difference is subtle, but it's definitely there.

strtdv

As a general rule (and using all sorts of clichés) el84s give chime and a sort of upper mid focused breakup. 6v6s give a fuzzier sort of breakup

mfin

Which amp are you getting? Otherwise surely you're trying to compare relatively smaller changes in sound via valve choice in an amp you havent played through?? Perhaps that video demonstrates in some way what you were curious about? ...although in the real world they would sound somewhat closer as you would naturally twist the eq and gain levels to taste.

ICBM

All other things being equal - which they aren't, as already said - then as strdv says... EL84s sound more crunchy, ringing and chimey, 6V6s sound softer, flubbier and fuzzier.

I prefer 2-6V6 over 2-EL84 generally, but I also like EL84s in fours, which sounds more complex and thicker, to me.

shaunm

ICBM;563352" said:

All other things being equal - which they aren't, as already said - then as strdv says... EL84s sound more crunchy, ringing and chimey, 6V6s sound softer, flubbier and fuzzier.

I prefer 2-6V6 over 2-EL84 generally, but I also like EL84s in fours, which sounds more complex and thicker, to me.

That's an interesting point as it would be two of rather than four.

welshboyo

Buy an Egnater Rebel and you'll have the choice of both...

crunchman

ICBM said:

All other things being equal - which they aren't, as already said - then as strdv says... EL84s sound more crunchy, ringing and chimey, 6V6s sound softer, flubbier and fuzzier.

I prefer 2-6V6 over 2-EL84 generally, but I also like EL84s in fours, which sounds more complex and thicker, to me.

For me the EL84 can sound a bit harsh but that probably can depend on the amp.

As to where I come down on this, I've owned 4 El84 amps that I can remember and 4 amps that use (or can use) 6V6s.  I've still got 3 of the 6V6 amps and I don't have any of the EL84 amps.

Edit:  To be fair, two of 6V6 amps I've got left are single ended.   I think that 6V6 sound much better in single ended amps than EL84.  The single ended configuration seems to make the EL84 sound harsh to my ears.

Chalky

+1 for EL84 crunchy-to-harsh and 6V6 warm-to-flubby. If your 6V6 amp sounded dark I'd stick a Jensen ceramic speaker in it to make it much brighter.

McToot

I had (and now regret selling) a Cornford Carrera, which was switchable from EL84 or 6V6 (or any other octal).  I found myself using the 84 almost exclusively, but then my preferred tone was more medium-gain rock a la ACDC.

Jeremiah

I have a VHT Special 6 Ultra, which comes with a 6v6, but I also have the valve socket adapter which lets you use an EL84 instead.

My experience is that the EL84 has more mids, less headroom and a smoother, more gradual onset of overdrive, while the 6v6 is more "all or nothing" when it starts to break up.

This is a single ended amp, so a push-pull amp might not respond the same way.

shaunm

Silly question but I've never really understood the whole push pull/ single ended thing. Can someone explain this to me in a really easy to understand format?

Dave_Mc

^ This is a very oversimplified, layperson's definition, but in push-pull you have pairs of valves (or valves with more than one valve within the valve) where half of the valves work on one half of the signal while the other half work on the other half. In practice, the vast majority of amps with more than one power valve will be push-pull (exception- laney lionheart), and even some amps with those dual valves i mentioned will be push pull too (e.g. blackstar ht5- it has one power amp valve but that valve is really two valves in one).

In single-ended the valves are working on all of the signal at once. In practice, most amps with a single power amp valve (so the wee 5 watters) are single-ended. Exceptions- the aforementioned Laney and Blackstar.

The advantage of single-ended is that you normally don't have to bias the power valve, it's just plug and play. Plus lower volume if that's a bonus for you. Disadvantage is they normally don't sound exactly the same as push-pull either.

(Some push-pulls don't have to be biased either- normally cathode-biased amps, but some non-adjustable fixed bias amps don't have to be biased either.)

shaunm

Thank you for that.......... So what's a class A amp?

jonnyburgo

Jeremiah said:

I have a VHT Special 6 Ultra, which comes with a 6v6, but I also have the valve socket adapter which lets you use an EL84 instead.

My experience is that the EL84 has more mids, less headroom and a smoother, more gradual onset of overdrive, while the 6v6 is more "all or nothing" when it starts to break up.

This is a single ended amp, so a push-pull amp might not respond the same way.

Is that adaptor plug n play @Jeremiah or are there any things you need to check out re. voltages? I have the standard special 6 and wouldnt mind giving it a go

Jeremiah

It's plug and play with the Special 6 range, VHT recommend checking with the manufacturer before using it with any other 6v6 amp.

Dave_Mc

shaunm said:

Thank you for that.......... So what's a class A amp?

That's kind of starting to get beyond my (very rudimentary) understanding. ) I think in (true) class A the valves are on all the time whereas in class A/B they're not. Again, that's a very oversimplified way of putting it.

It's also worth noting that the vast majority of guitar amps which claim to be class A, er, aren't. They're generally cathode-biased with no negative feedback (e.g. Vox AC30).

I think the Aiken amps site is generally regarded to have some pretty good info on this type of stuff (a lot of it, er, almost all of it, is well beyond me as well) if you can be bothered reading it.

http://www.aikenamps.com/index.php/what-do-the-terms-push-pull-and-single-ended-mean
http://www.aikenamps.com/index.php/what-is-biasing
http://www.aikenamps.com/index.php/the-last-word-on-class-a

(If anything in those links disagrees with what I've said, disregard what I've said and go by Aiken amps ) )

ecc83

shaunm said:

Silly question but I've never really understood the whole push pull/ single ended thing. Can someone explain this to me in a really easy to understand format?

Ok. Push Pull: Small diversion, ever heard of "Bridge Mode" as applied to power amps? This uses two identical amplifiers connected in such a way that you get a lot more power. That "such a way" is effectively in series. You will know I am sure that if you put two PP3 batteries in series you get 18volts? Now since power (into the same load) goes up as the square of the voltage, double the voltage and (all other things being equal, never are!) and you get 4 times the power.

Push pull operation is just a fancy way to put valves in series. Not really to do with one valve handling 1/2 the waveform since in many (full and proper class A) hi fi amps,  both valves are actually handling signal all the time! And THAT is what class A really means, that a valve or transistor passes current ALL the time for both positive and negative voltage excursions. This is very inefficient both in terms of valve usage (you need big valves for small output) and in terms of power consumption . A near class A AC30 uses almost as much juice when doing sweet FA  as when you are driving the nuts off it. A class A/B 100 watter will be consuming about the same resting power as the AC30.

Bias: All power valves need to be biased. This just means setting the standing current thru the valve(s). For "simple" lowish power amps (say sub 40W) this can be cathode bias which is just a resistor of precise value in the cathode circuit. This is a cheap and "failsafe" way to bias amps but not ideal for high power. Thus we have "fixed bias" where a subsidiary voltage, negative of chassis, is derived (in various ways) and applied to the OPValve control grids. This method is more expensive to do and does not afford the protection of Cbias but allows much greater power outputs.

Other advantages of PPull are. MUCH smaller OP transformer for a given power. Much easier to have low hum. PPull also cancels to a large degree certain types of distortion but that last is of little interest to us gitamp guys!

Dave.