Laney GH100L and EL34's

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Revson

Revson

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Hello everyone,

Long time lurker, first time poster here and I was wondering if anyone had experience with EL34's in the power section of the Laney GH100. I've done a search and didn't come up with too much so I thought I'd ask.

Basically, I want to make the amp a bit more Marshall sounding and don't actually want to buy a Marshall just yet. I've got other things I need to spend my money on right now, though I do plan on getting a Marshall in the future. Any thoughts on this? Opinions? Can I even get the Laney close to a Marshall?
 
Definitely go with EL34's. That will be way more Marshall than the 5881's.

Even though the Laney has the external bias switch you should have the bias checked after you swap tubes. The bias pot is inside requiring removal of the chassis.

And a few tweaks here and there can go a long way.

I would say that Laney makes a fine amp,very British. I love 'em ! but if you want a Marshall,get a Marshall. But the GH50L and GH100L are kinda like modded 800's especially with the footswithable extra gain stage.
 
Awesome, thank you. I'd love to get an old Marshall JMP one of these days, but right now I'm working on putting together a little studio and just don't have the cash available. I really like my Laney as is, but all my other amps have 6L6's and I'd like to be a little more diverse in the tone department. If I miss that 6L6 tone then I can always plug into the other power sections.

Is the bias switch usually that far off?
 
" Is the bias switch usually that far off? "

The switch just allows you to use either 5881's or EL34's, the bias needs to (should) be checked anyway. Who knows where the bias is set and for which type of tubes,know what I mean? FWIW I have switched from 5881's to EL34's and just flicked the switch with no problems,but I did go back and check the bias and it did need some adjustment.

Different preamp tubes make a big difference also. I swapped the ruby 12AX7's for Mullard re-issues a few years back and they sounded really fat, and just richer harmonics..I need to find some more of those. I would swap to EL34's and try different preamp tubes also. And just my opinion,but the Laney GH series amps sound best with V30's.This may be enough for you,if not :

Some tweaks to ponder.
If you don't have the experience working inside amps DON'T F*CK WITH THESE !!!! Take your amp to a qualified tech and let him do them if you so wish. These are really simple and shouldn't cost much at all.

I have had good results with a simple resistor swap also.All props for this go to Eric Hellstyle on the Harmony Central forums.
Change the 1m R14 to 470k (or anything in between) the lower R14 helps to reduce fizz and open the tone up a bit, experiment here.
you could use even a lower value, like 68k, and that brings a great improvement to tone, but would eat too much saturation(and we don't want that do we?)

Also, the 68k input resistor can be reduced (10k or anything in between) Reducing the input resistor improves dynamics, reduces fizz and will thicken up the raw guitar signal into the first stage.
 
That's great, thank you. I can handle all those tweaks and they're all really simple to make what seems to be a very welcome difference. It looks like both swaps are affecting only the first gain stage of the amp.

Biasing is one area that I'm really unfamiliar with, but I've found the bias adjust pot on the schematic and have been doing a little reading. If I understand it correctly, I need to wire pins 1&8 of the socket together, then attach a 1 ohm resistor from either pin to ground. Once I do that, I measure the mV drop across the 1 ohm resistor and that will translate directly to mA's. From there I just adjust the trim pot until I hit somewhere between 35 and 40mV.

Does that sound right?
 
A bias tool makes it a lot easier but if you don't mind doing the soldering then either way. I always thought you solder the resistor from pin 8 to ground? Maybe it's the same thing wiring it to pin 1 if that goes to ground anyway? Anyhow, always double check the research before you get out the soldering Iron. 35ma to 40 ma is usually about right on but you are supposed to run the milliamp/millivolt number multiplied by the plate voltage number off of pin 2. like .040X500 = 20, which would mean you are running 20 watts at idle which is high since an el34 is a 25 watt tube. 20 watts would be 80% you usually want to do down to about 70 % for longer tube life even though the amp could sound sweeter if it was a little higher but at the sacrifice of tube life. There are other formulas and methods for biasing but that is what I do. Also always remember to turn all the volume and tone knobs down before you bias and of course ALWAYS HAVE YOUR METER GROUNDED FIRST THING.
 
That is a good link. I had forgotten pin 3 is plate voltage, not 2. I have had a weber bias rite for about 7 years, so I don't do that method anymore. But I used to and it's really not that hard. Just gotta be careful and don't rush, it's potentially dangerous.
 
EL34s would get it closer.



I was keen on the GH50L, but only could find the TT100H. I tried it but it was noisy and a bit fizzy, so much so that it turned me off Laney for a while. I started getting interested in Laney amps again but by then I had bought my own true blue Marshall so, that was that.
 
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