Taming down a marshall plexi

[toolstudio]

Hi,

I just got a 100W marshall plexi for our studio.

As she is really loud, somebody told me to pull 2 of the power tubes, so it
get's more like 50W. Does it change the sound or would something like a Z Brake
and keeping the 100W make more sense.


wolfgang

[RUSCO]

It will change the sound a bit. Either way you go there will always be a change in sound as the dynamics of the speakers are different at different power levels.
Pulling out two of the output tubes is a better deal as there's no wasted energy like the ZBRAKE.
You could also try changing the inverter tube to a lower gain like 12AU7.

[kafka]

You should be fine to take a pair of the power tubes out. Make sure you take one out of each side. You should also move your speaker connection down a notch. (i.e. if you're using a 16 ohm cabinet, plug it into the 8 ohm socket)

A 100 watt and 50 watt amp have a different sound. 100 watts isn't so much louder than a 50 watt, as much as it has more clean headroom. The 50 watt will give you a tighter distortion sound, and the 100 will feel looser and more dynamic. Keep in mind, I'm not talking about differences in wattage, per se. I'm really talking about whether you're spreading our output across 2 or 4 output tubes. They're both useful. Use whatever sounds right.

The Z Brake is a good idea. 50 or 100 watts is an awful lot of power for studio or home use. The Z Brake should give you some relief.

[FFTT]

Something else you might try is running it through an 8X10 cabinet if you happen to have an SVT cabinet handy. Definitely worth a try.

That's what I'm doing with my Bad Cat Hot Cat 100R Head and it makes a world
of difference.

[mplancke]

Originally Posted by FFTT

Something else you might try is running it through an 8X10 cabinet if you happen to have an SVT cabinet handy. Definitely worth a try.

That's what I'm doing with my Bad Cat Hot Cat 100R Head and it makes a world
of difference.

Two cabs on a 100 watt head will act much like a 50 watter with one cabinet.

[Musiclab]

Personally there is something about 100 watt amps I like , I'd get a powerbrake and attenuate just alittle. They run hot but they sound great enjoy

[max cooper]

My amp tech always says that power attenuators can screw up the tranny. Anyone know about this?

[Musiclab]

I used one on a Hiwatt 100 for years, for a while 6 nights a week with the amp nailed. Never a problem. Thats a myth about them screwing up your amp, although if they short out or the speaker cables short out you could have a problem

[kafka]

Originally Posted by max cooper

My amp tech always says that power attenuators can screw up the tranny. Anyone know about this?

Absolutely. Marshall used to warn that use would void your warranty - until they came out with the PowerBrake, that is.

And they were right - to a point. If you can't dissipate the energy off the OT, heat will build up and you'll melt it. This can happen a number of ways. The easiest way to melt your OT is to play without a speaker. You can think of that as trying to play into a speaker with an infinite impedance. A variation is to play with a speaker that doesn't match the output impedance of your amplifier.

Now, there's some variability to this, as an 8 ohm speaker is only 8 ohms on the average. It may (in reality, will) be more or less, depending on the frequency and also how hard it's being pushed. It's an important element to the sound of the speaker.

You can see why a manufacturer who has designed a product that dissipates 50-100 watts through a specific speaker would be skittish about allowing it's customers to experiment with this at the company's risk. There are a lot of things that can go wrong. The first of which would be improper connection of the attenuator - not to mention potentially faulty wiring, or the use of a non-reactive (i.e. constant resistance/impedance) load on the amp output. (the last isn't necessarily a problem, but just may be something the engineers didn't consider when designing the amp). Some attenuators (for instance, my Jim Kelley FACS), use a pair of large wire-wound rheostats. Wear on the contacts could also potentially cause a catastrophic failure.

Personally, I think that these fears were reasonable once, but unnecessary in practice today. Just about all of the attenuators now on the market have addressed the reliability issues that may cause failure. As long as the amp is able to dissipate into a reasonably close load, it doesn't matter what that load is any more than it matters what brand of speaker you're using.

[FFTT]

The reason I mention the SVT cabinet is because these vintage CTS bass 10"s are heavier duty and take more to push them than your standard guitar speakers.
So even with a 4 Ohm load, the heavier speakers seem to do a better job of distributing the sound so I can set the amp for good tones at somewhat reasonable volumes allowing me to work with it comfortably.

The amp still breaks nicely, the crunch is good, the highs are still crisp and the feedback soars when you want it to in overdrive.

The same amp through a Single Vintage 30 in an open back cabinet at a volume setting of 2 was painful. Seriously painful.

If you can't find an SVT cabinet, try an EV 15" or try to find a vintage Hiwatt cabinet
loaded with heavy duty Fanes.

Or you can try the old tried and true moving blanket method.

Sofa cushions can come in handy too.

[Bob Ross]

25+ years ago I played in a band with a Steve Milne* who used a Marshall 50 watt plexi, and even that thing (into a single Marshall 1960 4x12" cab) was too loud for most club or studio situations. Probably because he had it dimed most of the time!

He tried a Scholtz PowerSoak for a while but didn't like the way that affected his tone or dynamics.

The solution he eventually came up with, which turned out to be surprisingly effective, was to build a small gobo stuffed with fiberglass insulation that leaned up against the cabinet & covered two of the four speakers.


*btw, Steve is now VP of Engineering for Euphonix!

[FFTT]

Moving blankets actually to a pretty good job of helping to control stage volume.

Same thing as mentioned above, you can drape them to cover half the cabinet
or even use bungie straps to help keep the blanket in place.

For recording, take the head into the control room and just mic up the cabinet
in the isolation room unless the player wants to work with feedback.

[Musiclab]

Originally Posted by Bob Ross

25+ years ago I played in a band with a Steve Milne* who used a Marshall 50 watt plexi, and even that thing (into a single Marshall 1960 4x12" cab) was too loud for most club or studio situations. Probably because he had it dimed most of the time!

He tried a Scholtz PowerSoak for a while but didn't like the way that affected his tone or dynamics.

The solution he eventually came up with, which turned out to be surprisingly effective, was to build a small gobo stuffed with fiberglass insulation that leaned up against the cabinet & covered two of the four speakers.


*btw, Steve is now VP of Engineering for Euphonix!

I always found the soak worked better with 100 watt amps for some reason, and you never really want to attenuate more than 3 db

[MattHahn]

i have done some research on that topic lately and i ended up using yellow jackets and convert the amp to el84´s.This will change the sound slightly but imo it sounds much better than a soak and pulling two tubes out of a 100watter doesnt make it much lower in volume.
But, even two yellow jackets in 100watters dont make ´em a bedroom amp.

[doorknocker]

Originally Posted by max cooper

My amp tech always says that power attenuators can screw up the tranny. Anyone know about this?

I tried to use a Power Brake with my Marshall Super Lead some years ago and the amp died within hours.......also I didn't like the sound at all.

I used to take out 2 power tubes on the Super Lead for live use but the difference in volume was small and the sound got worse too. But I know some blues harp players that had luck doing this with Fender Twins.

[AllAboutTone]

I never tried to tame my 100 watt plexi down, i wanted to to speak !!!

[jigsawlogic]

Haven't used it personally, but have heard good things about the Ultimate Attenuator:

The Ultimate Attenuator
Magus Innovations Ultimate Attenuator: Harmony Central User Reviews

[Geetarpicker]

You need to get an attenuator if it's too loud, but you really want it's fully cranked tone for recording. The THD units sound really nice with Marshalls. You can pull 2 tubes, but it will still be almost as loud. You will probably be amazed at how little a difference pulling 2 tubes really makes. Also, it won't sound as good and it will be harder on the remaining 2 tubes as the plate voltage goes up.

You could have a master volume installed, but they never quite sound as good as cranking into a good attenuator.

[FFTT]

I was kinda hoping that you might have tried the Ampeg SVT 8X10 or 15" bass cabinet experiment by now to see what you think.

I know it has made a tremendous difference working with my Bad Cat Hot Cat 100R.

The volume was painful at anything above 2 through a normal single 12" or 2X12 loaded with Vintage 30's , yet I can run it cranked if I want to through the SVT
cabinet without making my ears bleed.