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Mesa 20/20 vs Marshall EL84 20/20?

DJD100

Experienced
Hi, I'm looking to get one or the other of these to run my Ultra into with various guitar cabs, so I'm looking for any feedback from those that use these?

a) Which amp sounds better?

b) Mesa "Deep Mod", necessary?

c) Marshall "Deep Switch", usable?

d) I understand the Mesa to be 13lbs, and the Marshall 10lbs, does that sound correct?

e) Thoughts regarding either?

f) Which seems to have the most clean headroom?

Thanks...

Doug

P.S. I'm not interested in FRFR for this project as I'm only doing electric guitar (clean thru vintage mid-gain, thru early EVH at the gainiest), plus I'll be needing all the DSP I can get for multi-amp patches, so losing the Cab Block(s) is a good thing for me etc.
 

iceman

Member
I've owned them both but it was a looooong time ago. From what I remember they both sounded fantastic but I preferred the Mesa for it's volume (seemed a bit louder than the Marshall) and because I thought the Marshall's 'Deep' setting added too much bass and sounded artificial. Just my two cents tho. Both are awesome amps overall.
 

Deltafit

Inspired
I've only had experience with the Marshall 20/20. Good sound, I actually quite liked the deep switch and it certainly does give a hefty boost around the 80-100hz area. Definitely beefed up my tone. And for 20watts, its pretty damn loud! However, if you play with a really loud drummer and/or loud backline you might wanna consider something with a bit more headroom and kick. IMO.

Or..and btw, (i'm not sure how experienced you are so forgive me if i'm wasting my words here but..) should you decide to go with the Marshall, make sure you plug in BOTH outputs to a load (cabinet) at ALL TIMES. Mine came switched on without me knowing and when i plugged it in it turned on and instantly blew. When i came to sell it, the guy turned it on without plugging both ouputs into a load and it blew on him too. (Then wanted his money back!!) But thats another story :lol:

Good luck.
 

BBN

Fractal Fanatic
I own the Marshall, and have tried the Mesa.
They're both nice little amps.
Sound similar when the deep setting is not engaged on Marshall.
I did however like the deep setting, i found it very useful.
Mesa had more headroom though.
With the amount of tweak-ability on the Axe...the Deep setting can be simulated.

I don't think you can go wrong with either.


BUUUUUT!!!!! The one thing that stinks about the Marshall is that you HAVE to use both channels on the amp at all times....so if you're only running one side, into a 1x12 cab or something like that....you will fry the amp.

I had mine custom wired so I could 'turn off' one side of the amp....but just an FYI, a stock model HAS to be run with a stereo cab (or two cabs).

If you want more info on that....Google it...lots of info.
 

DJD100

Experienced
Thanks everyone, great info!

I bought a used Mesa 20/20 yesterday so I did the Deep Mod on Chan B and left Chan A stock. I'll be going to the studio later today and trying both through various cabs with the Axe. The Deep Mod is just removing the Cathode Bypass Cap which removes the high-pass filter, but lowers the gain of V1 too. Better would be to increase that cap's size a bit, so I'll be trying that as well (between 10uf - 20uf). I'll likely get a couple of push-pull pots and make the mod switchable as well if the Mesa turns out to be the winner.

The Mesa Manual states that you can run just one side of the amp as long as you don't run signal through the non-speaker connected side, then dime it's presence and minimize it's volume control.

Thanks for the help!
 

DJD100

Experienced
Well, upon further review I've decided to add my version of the Deep Mod to both channels. The typical Mesa Deep Mod is to remove V1's 1uf Cathode Bypass Cap which does extend it's low freq response, but that approach also loses gain which is bad. It's better to replace V1's 1uf Cathode Bypass Cap with a 22uf cap which will extend the Mesa's freq response down to 10Hz or so, but without any gain loss.

I'm going to roll with the Mesa 20/20 seeing that it can work in mono without any problems, and seeing that they seem much more robust than the Marshall 20/20's. The Marshall has a smaller 1U case with the tubes inside so it runs a lot hotter than the Mesa (which has it's tubes hanging out the back of it's considerably larger 1U case).

Just curious BBN, what did you do to mod your Marshall to allow it to be used mono, kill the B+ to the output tubes or something?

Thanks again for the help everyone!

DJD100 said:
Thanks everyone, great info!

I bought a used Mesa 20/20 yesterday so I did the Deep Mod on Chan B and left Chan A stock. I'll be going to the studio later today and trying both through various cabs with the Axe. The Deep Mod is just removing the Cathode Bypass Cap which removes the high-pass filter, but lowers the gain of V1 too. Better would be to increase that cap's size a bit, so I'll be trying that as well (between 10uf - 20uf). I'll likely get a couple of push-pull pots and make the mod switchable as well if the Mesa turns out to be the winner.

The Mesa Manual states that you can run just one side of the amp as long as you don't run signal through the non-speaker connected side, then dime it's presence and minimize it's volume control.

Thanks for the help!
 

BBN

Fractal Fanatic
I brought it to DST Amps (Bob Detore). He did the mod....and I have no idea what the specifics are.
He told me he would install a switch in the back that would put one side of the amp into a 'standby'.
Sorry I don't have more info...but Google DST Amps and Bob....and shoot him a note.
He's a great guy.
 

DJD100

Experienced
Thanks BBN!

If DST created a "standby" switch then he's just interrupting the B+ to the output tubes while leaving the heaters on.

Thanks again...

BBN said:
I brought it to DST Amps (Bob Detore). He did the mod....and I have no idea what the specifics are.
He told me he would install a switch in the back that would put one side of the amp into a 'standby'.
Sorry I don't have more info...but Google DST Amps and Bob....and shoot him a note.
He's a great guy.
 

jimosity

Member
I've had both.
The Mesa sounded and 'felt' better to me.
The Marshall was darker and not in a great way I didn't think.

I did the depth mod to my Mesa 20/20 and it was so very much worth it.
Don't hesitate (or send it to me and I'll do it for you for a small fee plus return shipping) to do that mod, it totally opens the 20/20 up to better tone.
 

AdmiralB

Experienced
The Marshall in stock form runs the power tubes waaaay too hot. B+ is over 400V, and the factory bias instructions (sticker inside the chassis) has you set them to over 100% idle dissipation. The amp is a lot happier if you cool it down to 60%-70%. Otherwise, it's an excellent amp, as far as 1U tube units go.

None of them have the depth of (physically) bigger amps, because you just can't fit much by the way of output transformers inside a 1U form factor.

If you only want to use one channel on the Marshall, just don't plug an input into that side. Wouldn't be a bad idea to fab some kind of load for that channel too, just to damp any possible oscillations (small resistor on a phone plug, wattage and value not terribly important). Lifting B+ is a bad idea; you'll poison the cathodes.
 

grega-60438

New Member
I have the Mesa 20/20. Whenever I mix guitars at the studio, I typically run a high pass filter at about 60Hz. 80Hz is typically where the guitar frequency starts. I have been taught to keep mixes out of the low frequencies unless it serves a good purpose as it can muddy the mix and suck up power from the final mix sound. In reference to the deep mod, I guess I do not understand why going to 10Hz would be a good thing. Does it create pleasing harmonics in the hearing range?
Do you run the deep mod frequencies and then also high pass filter at 60Hz in the mix? Sorry if these seem like weird questions. They are questions from a mixer and masterer that is willing to learn new things.

Greg
 

DJD100

Experienced
The Mesa 20/20 has a Cathode Bypass hi-pass on V1 that results in what is perceived as a low-mid boost with limited lows. This works well with the Mesa Triaxis in creating the Boogie sound.

For those requiring a flatter response the Deep Mod, or better yet the bigger Cathode Bypass cap removes the perceived low-mid boost and extends the lows. This is possibly better for folks using non-Mesa guitar preamp's looking for a flatter power amp response, and for those using lower tunings.

You are correct in that you'd likely hi-pass this stuff in the mix, and of course the Axe has lot's of EQ possibilities to do this as well.

In short, the mod makes the Mesa 20/20 less colored in the low-mids and gives it better bass. Some folks have replaced the volume knobs with push-pull switched pots so you can switch the mod on and off per channel, which seems like the best method if one needs both sounds regularly.

grega-60438 said:
I have the Mesa 20/20. Whenever I mix guitars at the studio, I typically run a high pass filter at about 60Hz. 80Hz is typically where the guitar frequency starts. I have been taught to keep mixes out of the low frequencies unless it serves a good purpose as it can muddy the mix and suck up power from the final mix sound. In reference to the deep mod, I guess I do not understand why going to 10Hz would be a good thing. Does it create pleasing harmonics in the hearing range?
Do you run the deep mod frequencies and then also high pass filter at 60Hz in the mix? Sorry if these seem like weird questions. They are questions from a mixer and masterer that is willing to learn new things.

Greg
 

mhd1970

Inspired
I bought my 20/20 from a kid whose dad is an EE and helped him do the deep mod such that it can be switched in or out with a toggle in the back. After playing around with it a little I set it to the deep mod and haven't looked back. Just sounds way fuller and more pleasing to my ears. I suppose the stock mid-punch might be great for certain tones and cutting through the band, but the fuller sound of the deep mod seems a better fit for the many rabbits you can pull out of the Axe-FX hat.
 

DJD100

Experienced
I agree, and it's important to note that the Axe has plenty of EQ options available to duplicate the stock 20/20 freq response if desired, say with Mesa models for example.

I will say that adding the bigger Cathode Bypass Cap vs just removing it is the way to go as you get the same freq response without losing any gain.



mhd1970 said:
I bought my 20/20 from a kid whose dad is an EE and helped him do the deep mod such that it can be switched in or out with a toggle in the back. After playing around with it a little I set it to the deep mod and haven't looked back. Just sounds way fuller and more pleasing to my ears. I suppose the stock mid-punch might be great for certain tones and cutting through the band, but the fuller sound of the deep mod seems a better fit for the many rabbits you can pull out of the Axe-FX hat.
 

dukemcrae

Inspired
I have both, always enjoyed the Marshall better, plus I was always running stereo anyway, but since going FRFR along with my Axe Fx 2, I have both for sale in great condition if anyone wants, otherwise it's off to eBay!
 

Josie

New Member
I'm British and I think Marshall amps are good but I have just had such a condescending refusal to send me the circuit diagram of their EL84 20-20! My money is thus on MESA Boogie. They don't seem to treat us as small children or, worse, the don't want to sideline me like Marshall because they perhaps believe this is not an area for us girls! Bloody cheek. I wish I'd spent the little more and got the MESA 2020 to go with my MESA Boogie Triaxis!!!! Huh!!!!n Girls like using ass kicking amplifiers too and we like to mod them!

Grrrrrrrrrrrr....
 

Sixstring

Axe-Master
I'm British and I think Marshall amps are good but I have just had such a condescending refusal to send me the circuit diagram of their EL84 20-20! My money is thus on MESA Boogie. They don't seem to treat us as small children or, worse, the don't want to sideline me like Marshall because they perhaps believe this is not an area for us girls! Bloody cheek. I wish I'd spent the little more and got the MESA 2020 to go with my MESA Boogie Triaxis!!!! Huh!!!!n Girls like using ass kicking amplifiers too and we like to mod them!

Grrrrrrrrrrrr....
Ha, funny first post :lol I liked the Mesa 20/20 but for the Axe it had too big of a sonic foot print for me.
 

Mark's Tone

Power User
I'm British and I think Marshall amps are good but I have just had such a condescending refusal to send me the circuit diagram of their EL84 20-20! My money is thus on MESA Boogie. They don't seem to treat us as small children or, worse, the don't want to sideline me like Marshall because they perhaps believe this is not an area for us girls! Bloody cheek. I wish I'd spent the little more and got the MESA 2020 to go with my MESA Boogie Triaxis!!!! Huh!!!!n Girls like using ass kicking amplifiers too and we like to mod them!

Grrrrrrrrrrrr....
Welcome to the Forum:eagerness:
Years back I was aquanted with a smokin' hot brunett that used to like working on cars.
She was a knock out grease monky. I can see chics digging the amp mod thing. I like girls......
 

PacoCasanovas

Fractal Fanatic
Grrrrrrrrrrrr....
You don't have to - send a PM, if you still looking for the Marshall 20/20 service manual..... ;)


Regarding the standby switch on a boogie. Just place the switch between the cathodes and ground of your power tubes and your tubes were safe again! No plopping noise either.
Regarding Deep-Switch on the 20/20 of the Marshall EL84 - there is no cathode bias capacitor on V1, the deep circuit is just made by a filter in the negative feedback loop - just as the presence control.

Have fun!

I like girls......
:lol as most of us, I guess....:mrgreen

cheers
Pacosipulami
 
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