Erm, I require amp help please!!

[Mr Ed]

Ok, some (enh) may have seen my other thread about my amp problems. It died. Got it fixed. It died again. Got it properly seen to by an amp tech and now it's fine, one of the parts which powers the tubes was damaged. Sorted. Routine service.

All well and good.

However, got it to practise tonight and it's running fine and all... apart from the sound is WAY off!! I have been very proud of my sound over the last 18 months, it was so totally balanced and wonderous but tonight was just an undefined, trebley mess. It sounded horrid.

:(

Fernandes Ravelle Deluxe (mahogany body, maple neck, rosewood board)
LOTS OF PEDALS!!
JCM900 4100 (running at 50W) head into 1936 2x12 wth Vintage 30's.

Now... the warm rounded tone of the mahogany has always provided the low-end, the Seymour Duncan JB and natural trebleness of the JCM900 provided the top-end and the mid-range spike from the speakers left me with a very natural tone.

THen I'd set the EQ - lots of mids, hardly any bass, bit of treble, little bit more presence and BAM, heavenly tone.

Now, the only thing that has changed is that when I had it retubed, I asked for te 5881's in the power amp to be replaced with EL34's. I believe this is supposed to provide a warmer sound but I'm yet to hear it!!

CAN ANYONE GIVE ME HELP?! And please, I'm not after "you need to change that pickup" or "JCM900's suck" - the setup has always worked up til now... unless this could be a permanent change.

Weird thing is, just to check, I stomped on my MXR 6-band EQ pedal, set to a gentle mid-range boost for solos and all of a sudden it just sounded like me!! But I don't wanna have to use my EQ all the time, I need it for solos!!

Is it that the tubes need breaking in? If so, what's the best way to do that?

Many thanks in advance if anyone is able to help...

[Henk]

My JCM800(EL34) has alot less mids them my Bluesbreaker(6L6).

This is what i do with my JCM800 on the clean channel to let have the characteristics of the BB (it still has a 'deeper' sound), bass on noon, mids on 1 o'clock, highs on 2 o'clock, presence on noon(at least but usually more). It seems to lack mids but actually it needs more highs to balance it out, maybe thats what you need to try.

Just let it all sink in a bit, your '900' is versatile enough to get it on track again.

GL, Henk

[Will]

Personally I have the treble quite low, and have the presence on a mid to high level, about 5-8.
Also cut the treble quite a bit with an EQ, best balanced sound I know of :)

Just for reference of the rest of the sound, I run the mids on the amp low, and have them higher on the EQ, and the bass on the amp on about 9, and cut quite low on the EQ

[Oli]

With my 900s, i find i have to keep tweaking the treble and presence controls to balance out the sound. Bear in mind that new tubes will sound different, and they will break in a little bit, so i'd imagine that the harshness will go away after a bit- just torture them! :)

[Mr Ed]

Thanks so far dudes, I'm hoping it's all gonna settle down and let me get back to doing what I do - deafening my band, one by one.

[LazyNinja]

can't you use an overdrive to thicken it up and use your EQ for solo boost?

[Mr Ed]

If I absolutely had to, I suppose... but I don't like using external drive pedals.

[LazyNinja]

If you get a good boost I find that most of the time it sounds better than using the amp's distortion alone. Set it to mid gain and use the boost to really drive it up. Fulltone OCD is meant to be the best for this purpose but I'm quite happy with my zoom power drive which I got for £20. Bad Monkey and Boss SD1s go for less than £30 on ebay too.

[FELINEGUITARS]

I'm assuming that amp was rebiased for EL34s correctly.....

5881s do sound very different from 6L6s
My Marshal 9100 power amp has 5881s and it sounds very full and has a lot of top and a lot of bottom too.
Comapred to it a EL34 power amp can sound a bit nasal

I know that the Marshall sound post 1970 is based on the EL34, but there is a chance that you have gotten very used to the 5881 sound which I can relate to. It may just be that the EL34s come as a culture shock.

I guess they do have a lot of midrange but to my ears they dont sound so full compared to the 5881s

[Mr Ed]

I guess they do have a lot of midrange but to my ears they dont sound so full compared to the 5881s

This is what I'm founding out. I might have to $%&#ing swap back then. D'oh.

Would that need re-biasing again or is that only for preamp tubes? :(

[Twinfan]

I wouldn't describe EL34s as warm - they're more crunchy and biting.  That's your problem I think.....

You'll need to rebias for different valves.

[Mr Ed]

You'll need to rebias for different valves.

cr@p.

[LazyNinja]

You only need to bias power valves. You don't need to bias preamp valves.

Edit: I suggest you give EL34L valves a go. They sound a bit fuller and bigger in my opinion.

[Mr Ed]

You only need to bias power valves. You don't need to bias preamp valves.

For the sake of my sanity, it really should be the other way round!!

Thankfully, the guy who runs the practise rooms where my band plays (and where my amp currently is) told me last night that they have an amp guy who does tubings and biasings and what-not. I've texted him to see how much it'd be if I buy the tubes myself, a quad of JJ 5881's is only £35 or thereabouts from HotRox so I'd look at getting that done asap. Can't imagine it'll be more than about £20.

[Mr Ed]

Suggestions on brands/particular types of 5881's? Difference between 5881's and 6L6's?

HotRox have recommended that I stick with either:

Sovtek 5881wgc (standard) - £34 for a matched quad.

or

Tungsol 5881's - £58.00 for a matched quad, warmer and smoother apparently but I don't like the extra cost.

or

For extra headroom and output, Sovtek 6L6WXT+ which is £42 per matched quad.