EL84s in high gain/multi-function amps

StefB

How well do EL84s deal with both high gain and the high versatility demands thrown at them by, for example, H&K's 'meister range?

The current crop of trendy lunchbox amps favour EL84s, presumably mainly for space saving reasons given they aren't generally associated with high gain.  So is it just a perception thing in our (my!) minds, because EL84s are primarily associated with the chimey clean and medium gain likes of Vox that they aren't as 'good' as EL34s and 6L6s for hefty low end and bruising crunch applications?

I understand it more in the 18w amps for power rating purposes and there won't be much spare room in a Tubemeister 36 head, but if they can fit 4 x EL84s in then wouldn't 2 x EL34 also somehow fit to get in the same 36 - 50w ballpark?

Drew_TNBD

I think they sound a bit fizzy and overly treble-heavy. Was the main reason I didn't stick with my Dual Terror, other than lack of clean headroom.

digitalscream

Drew_fx said:

I think they sound a bit fizzy and overly treble-heavy. Was the main reason I didn't stick with my Dual Terror, other than lack of clean headroom.

Funnily enough, the my JCA22H (EL84s) seems to subjectively have more low-end grunt than my JCA50H (KT66s).

ecc83

I would assume H&K went for the "sound" of EL84s? 

Then, 84's are easy to cathode bias* just a resistor and a cap.You lose a trifling 10-12volts in such an arrangement. But such biasing of an EL34 will lose you many more volts, typically 32-36V and that eats into your headroom and means the HT has to be higher, costlier mains traff, caps di da... 

Of course 34s are most often fixed biased but that in itself means a lot more circuit complication and the "proper" way to do it is  a special winding on the mains traff. 

*H&K claim an "autobias" valve saving system. I can't find a schematic so I don't know if it is just a cathode resistor and a bit of adman's puff!

Dave.

ICBM

It's because the traditional use of EL84s is in cathode-biased amps. Run them fixed-bias and they sound very similar to any other valve - they do have a slight 'EL84 sound' but it's easy overridden by the rest of the amp. The 'chime of EL84s' is mostly a cathode-bias characteristic.

Two EL34s can give a very similar amount of power but it's a slightly more expensive way of doing it. They're more usually used to give even more power though, because they can - 50W from four EL84s is really pushing it and relies on some creative measurements, whereas it's easy from two EL34s and they can go higher.

randomhandclaps

I've owned a few EL84 amps but have never been satisfied with the tightness of the bass end when driven really hard.  Compared to my EL34 or 6L6 amps it's not so much a lack of low end completely, it just tends to sound a bit ragged when pushed to equal levels.   I would love a sub 50w amp for recording but I just can't find one I am happy with.

digitalscream

Ah, that makes sense - my JCA22H is 2 x EL84, fixed-bias. That would account for the fact that it doesn't sound chime-y at all...

Drew_TNBD

Ahhhh... that explains it. The Orange stuff is cathode biased AFAIK. What about the Mesa Mini-Recto, is that cathode or fixed?

fastboy

Obviously not a lunch box amp but talking of high gain and El84's, the Cornford Hellcat springs to mind. 

I know some don't like the clean channel but the high gain channel is awesome and one of the best amps I've used live for cutting a mix (and I've owned and gigged maybe 60 different amps at a conservative guess)

ICBM

Drew_fx said:

Ahhhh... that explains it. The Orange stuff is cathode biased AFAIK. What about the Mesa Mini-Recto, is that cathode or fixed?

I could be wrong - I don't have the schematic, or have opened one up - but I'm sure it's fixed in 25W mode, and it may be cathode in 10W. It sounds quite a lot more compressed as well as lower in power, to me.

Yes, the Orange TTs are cathode biased. Unusually, so is the Rocker 30, using two EL34s - but to me it sounds far better than the 4-EL84 models like the AD30 (which is also cathode bias).

crunchman

I did find them a bit harsh and lacking low end thump in some of the EL84 amps I used to own.  As stated above, this is partly down to the circuit design, but I think it is partly a characteristic of the valves as well.

I have a VHT Special 6 (Single Ended 6V6).  The Valve Junior I had before definitely had some harshness in the upper mids that the special 6 does not.

ThePrettyDamned

The orange ad30tc sounds like it gets pretty gainy

As a contrast, the rocker 30 sounds absolutely delish and had el34s I think, but only 30 watts so must have been wired a little different to the norm. Sorta like the laney lionheart, with 5 (yup, 5!) el34s to give 50 watts?

The thunder 30 is mega high gain sludge and metal heaven, apparently. And that's el84 iirc.

ICBM

ThePrettyDamned said:

The orange ad30tc sounds like it gets pretty gainy

As a contrast, the rocker 30 sounds absolutely delish and had el34s I think, but only 30 watts so must have been wired a little different to the norm. Sorta like the laney lionheart, with 5 (yup, 5!) el34s to give 50 watts?

Yes. The Rocker 30 is push-pull cathode bias with two EL34s - it may just be true Class A, although I haven't scoped one… it's just possible at that power output. The Laney Lionheart is even more unusual - it's parallel single-ended, 20W from four EL84s or 50W from five EL34s depending on the model, and is true Class A... or as much so as any guitar amp ever will be!

The AD30TC does have a lot of gain but I find it very muddy-sounding when it's pushed hard. Part of that is the cathode bias, and part is the valve rectifier - which I normally like, but it's too saggy in this amp. Luckily replacing it with a solid-state plug-in is dead easy, tightens and brightens it up and cures the blowing rectifier (wrong standby switch position) problem at the same time.

ThePrettyDamned

ICBM;69924" said:

ThePrettyDamned said:

The orange ad30tc sounds like it gets pretty gainy



As a contrast, the rocker 30 sounds absolutely delish and had el34s I think, but only 30 watts so must have been wired a little different to the norm. Sorta like the laney lionheart, with 5 (yup, 5!) el34s to give 50 watts?





Yes. The Rocker 30 is push-pull cathode bias with two EL34s - it may just be true Class A, although I haven't scoped one… it's just possible at that power output. The Laney Lionheart is even more unusual - it's parallel single-ended, 20W from four EL84s or 50W from five EL34s depending on the model, and is true Class A... or as much so as any guitar amp ever will be!

The AD30TC does have a lot of gain but I find it very muddy-sounding when it's pushed hard. Part of that is the cathode bias, and part is the valve rectifier - which I normally like, but it's too saggy in this amp. Luckily replacing it with a solid-state plug-in is dead easy, tightens and brightens it up and cures the blowing rectifier (wrong standby switch position) problem at the same time.

That's pretty cool, nice to see a couple of brands trying something different! Never tried the orange, only the rockerverb (yummy). The laney, though, is probably the finest sounding amp I've ever heard for rock, blues, funk and pop. Just stunning (50 watter). Sadly, although I don't recall the head being mega pricey, the cabs were super expensive because of crazy high spec celestions.

I never actually tried it myself, but someone else in store (who could play tasteful music...) was, and I was in awe. Just that and a digitech reverb pedal, and it was sublime.

ICBM

ThePrettyDamned said:

The laney, though, is probably the finest sounding amp I've ever heard for rock, blues, funk and pop. Just stunning (50 watter). Sadly, although I don't recall the head being mega pricey, the cabs were super expensive because of crazy high spec celestions.

Yes, much as I love the Heritage G12H-30 - and usually criticise makers for using cheap speakers - it did seem a bit unnecessary to make the cab *so* expensive by using such a high-end one. Although they don't sound the same, the Anniversary H30 which is about half the price is a very good speaker too, and not that far away.

martinw

I personally don't like EL84s in higher gain amps. I think they affect the overall tone and prefer something with a flatter response.

Cirrus

If you want to have more bottom end definition, get your drummer to tune his F*cking bass drum for once.


)

ThePrettyDamned

Cirrus;69995" said:

If you want to have more bottom end definition, get your drummer to tune his F*cking bass drum for once.





)

I remember jamming some fast, double bass metal stuff with a drummer and bassist once and wondering what was wrong.

We were all in drop c, but his bass drum turned out to be a d or something, he'd never thought about it before. Once that was sorted, things sounded so much better, it was like night and day!

ICBM

I once did a gig with a drummer who had his kick accidentally tuned to the resonance of the room. It was so bad it was actually impossible for any of us to play properly... luckily the sound engineer realised what the problem was and was able to convince the drummer - who didn't like being told what to do with his drum kit - that it really was necessary to retune it.

ecc83

If I might add the B'star HT-20 to the debate?

This is a bit of a "two way street" It is about 30% cathode biased (and is therefore going to bias off a bit when punished) but has adjustable fixed bias and balance. 

Another factor here is that 50W ish EL34 FB  amps tend to have a bit of feedback whereas CB EL84 jobs don't. ....Just sayin'!!!

Dave.(can't recall if the HT-20 has NFB, will check)

Cirrus

Good call on the negative feedback.