IS a 50 wat jcm powerful enough

[Battle of trenton]

I have an origonal 50 watt JCM 900 no mods done. i am running it into a marshall 1960 4x12 and a crate 4x12. will the 50 jcm 900 be powerful enough to drive all these speakers?

 

[fitz]

I have an origonal 50 watt JCM 900 no mods done. i am running it into a marshall 1960 4x12 and a crate 4x12. will the 50 jcm 900 be powerful enough to drive all these speakers?

to the forum.
Yes, a 50w JCM900 will drive a pair of 412's enough for the neighbors to call the cops.
You may need to mic a cab to the PA for a stadium gig.

 

[Scumback Speakers]

I run my 50w through 2 4x12's a lot. Shouldn't be any issues.

 

[Scumback Speakers]

to the forum.
Yes, a 50w JCM900 will drive a pair of 412's enough for the neighbors to call the cops.
You may need to mic a cab to the PA for a stadium gig.

Since you mentioned the cops...http://www.scumbackspeakers.com/name.html

 

[Filipe Soares]

it will be loud enough to put you in trouble with the law.

 

[RLW59]

A 1 watt head can drive two 412's. Obviously not as loud as a bigger head, but you'll get 95~103 dB depending on the speakers. (Like screaming as loud as you can.) The amp doesn't work any harder driving more speakers -- it puts out the same amount of power whether it's driving 1 speaker or 100 speakers.

Power/volume is logarithmic, not linear. A 100 watt amp is only twice as loud as a 10 watt amp (through the same speakers), not 10 times as loud. A 100 watt amp is just slightly louder than a 50 watt amp (though the bass response may feel bigger and punchier). A 200 watt amp is slightly louder than a 100 watt amp -- it takes 1000 watts to be twice as loud.

Speakers make a huge difference in volume. "Efficiency" is a measurement of how many dB they produce when driven by 1 watt. An increase of 10 dB is roughly twice the perceived volume. Low efficiency speakers can be 92 dB, high efficiency can be 103 dB -- twice as loud with your amp.

Your 1960 probably has G12T75's which make 97 dB with 1 watt input. Changing to V30's would add 3 dB -- like doubling the amp's power (not double the volume, but noticeably louder).

(1960's are also available with V30's or Greenbacks installed, older ones had G12-65's, and of course yours could have had a speaker swap, but most have G12T75's.)

Crate could have anything. A few came with V30's, many came with the cheapest generic low-efficiency speakers imaginable.

 

[fitz]

Scumbacks Speakers: How We Got Our Name

www.scumbackspeakers.com

cool story.

 

[RLW59]

There are still some metal scenes where bands play crazy loud. If you're lucky enough to be in one of those subcultures, your rig might be marginal against the other guitarist's cranked 180 watt Diezel Herbert or 120 watt Bogner Uberschall.

In every other genre, your rig will be capable of being way too loud, and people will be telling you to turn it down.

 

[Matthews Guitars]

It'll deafen you if you play it a lot without ear protection. Think that's powerful enough?

 

[Leonard Neemoil]

Does the Pope shit in the woods?

 

[Scumback Speakers]

cool story.

All true, sadly. What a beyotch Ellen was.

 

[ElvisNixon]

A 1 watt head can drive two 412's. Obviously not as loud as a bigger head, but you'll get 95~103 dB depending on the speakers. (Like screaming as loud as you can.) The amp doesn't work any harder driving more speakers -- it puts out the same amount of power whether it's driving 1 speaker or 100 speakers.

Power/volume is logarithmic, not linear. A 100 watt amp is only twice as loud as a 10 watt amp (through the same speakers), not 10 times as loud. A 100 watt amp is just slightly louder than a 50 watt amp (though the bass response may feel bigger and punchier). A 200 watt amp is slightly louder than a 100 watt amp -- it takes 1000 watts to be twice as loud.

Speakers make a huge difference in volume. "Efficiency" is a measurement of how many dB they produce when driven by 1 watt. An increase of 10 dB is roughly twice the perceived volume. Low efficiency speakers can be 92 dB, high efficiency can be 103 dB -- twice as loud with your amp.

Your 1960 probably has G12T75's which make 97 dB with 1 watt input. Changing to V30's would add 3 dB -- like doubling the amp's power (not double the volume, but noticeably louder).

(1960's are also available with V30's or Greenbacks installed, older ones had G12-65's, and of course yours could have had a speaker swap, but most have G12T75's.)

Crate could have anything. A few came with V30's, many came with the cheapest generic low-efficiency speakers imaginable.

Sorry to clarify and slightly correct your comment, but I will. DbSPL is logarithmic as you say, but you’re not quite correct in the ratio one amp power and how it affects perceived “volume” measured in DbSPL.

The correct ratio of power vs volume is that you need to DOUBLE your amplification power to achieve an additional 3DbSPL of volume. That is always the ratio and it is logarithmic (Fletcher-Munson “Bell curve).

 

[V-man]

Lots of comments missing a large part of the discussion.

Will it drive them? Yes
Will it be loud? Yes
What about distortion?

Straight in, there are three basic elements to distortion: Preamp distortion, Power amp distortion, and speaker distortion (breakup).

Part of why Greenbacks were so glorious then and a timeless classic now is their low power handling (20-30w or 80-120w per quad) that broke up into that glorious distortion when assaulted by a 50w or 100w Plexi. In fact a 100w Suoerlead had a tendency to blow speakers, seeing how a full stack could be as low as 160w total and the 100w head could exceed that in RMS.

The opposite approach to somone like someone like Jimi above was Randy Rhoads, who ditched the classic GBs (BBs) that were popular at the time and even the 65s that were the other default choice for Marshall, opting instead for Altec Lansing 417 8H speakers that were 100w each or 400w/quad. Where Jimi pushed a 160-240w full stack with a 100w Superlead, RR pushed 800w in a full stack with his 100w Superlead.

The difference between a full bore Superlead pushing 160w of speakers and one pushing 800w (aside from the EQ/voicing of the different speakers) is how the former adds coloration from the speaker breakup into the signal and the latter does not.

Take your 50w 900. Plug it into a quad of GT 75s, wide open. It will be loud and full but compare it to a 212 with the same speakers. The volume will not be wildly different (perceptible) but the pair will be pushed harder than the quad and that difference should be heard.

Even further differences would occur if that head pushed a 112 cab with that speaker, particularly comparing a miced speaker in a single 112 vs a miced speaker with the amp pushing 2 quads. One recording would sound as if pushed much harder, (for better or worse -depending on the desired result).

 

[Scumback Speakers]

I've got the David Kowalski Dark Gene 1/2w amp. I hooked it up to a 412 cab with Scumback M75-PVC 65w in it. Trust me, it was surprisingly loud, enough you could almost play a blues jam with it.

With my Scumback 50w 1987 Plexi clone, two of those cabs were at ear damage level with the volume at 7 (NMV).

Just how nuts do you want to get? LOL

 

[swsidwilliams13]

A 1 watt head can drive two 412's. Obviously not as loud as a bigger head, but you'll get 95~103 dB depending on the speakers. (Like screaming as loud as you can.) The amp doesn't work any harder driving more speakers -- it puts out the same amount of power whether it's driving 1 speaker or 100 speakers.

Power/volume is logarithmic, not linear. A 100 watt amp is only twice as loud as a 10 watt amp (through the same speakers), not 10 times as loud. A 100 watt amp is just slightly louder than a 50 watt amp (though the bass response may feel bigger and punchier). A 200 watt amp is slightly louder than a 100 watt amp -- it takes 1000 watts to be twice as loud.

Speakers make a huge difference in volume. "Efficiency" is a measurement of how many dB they produce when driven by 1 watt. An increase of 10 dB is roughly twice the perceived volume. Low efficiency speakers can be 92 dB, high efficiency can be 103 dB -- twice as loud with your amp.

Your 1960 probably has G12T75's which make 97 dB with 1 watt input. Changing to V30's would add 3 dB -- like doubling the amp's power (not double the volume, but noticeably louder).

(1960's are also available with V30's or Greenbacks installed, older ones had G12-65's, and of course yours could have had a speaker swap, but most have G12T75's.)

Crate could have anything. A few came with V30's, many came with the cheapest generic low-efficiency speakers imaginable.

I have to agree with this comment. I ran my Silverface 5 watt bronco through my 4X12 cabinet and it sounded much better. The same with my Vox AC4, They both had more balls. But my ORANGE TH30 has a V30 in it and when I ran my DSL 15 head through that speaker. All my Overdrive went away. I shoulda tried a different speaker prior to making all those mods everyone was complaining about(myself included) I used to think speakers were speakers when it comes to amps and sometimes the difference is negligible, but I heard it first hand and it changed my opinion, forever.

 

[Nadir]

We guitar players should begin to learn from the HIFI world, where the rule is:
"half the budget to the speakers, the other half to all the rest".

 

[PentodeLicious]

50W marshal power amp is at approx 1% THD.
at full blast, probably around 30%-40% THD, it will be 90W RMS
My 2204 peels the paint of the wall only half way up.
It's exactly the same power amp design.

Regarding speaker wattage, it's at best an estimation at certain conditions.
You have Xmax that will likely happen way before the coil combustion in a GT-75 speaker.
in a greenback the coil will combust before reaching the Xmax most of the cases.
Also depends with ventilation and frequencies fed into the speaker.

Now when adding additional cabinet of 4x12 you actually increase the overall speaker sensitivity.
so you get 3db spl more.
In short yeah, 50 watt JCM 900 cranked with two 4x12 will get you arrested and deaf.

 

[Silverdome]

I played a JCM 900 SLX through a full stack at a bar gig and it was way too loud. It looked awesome and I can't remember where I had the volume at but I think I had it around 5 and I think I even rolled off some volume with the guitar. I think you'll be fine.

 

[Edgar Frog]

 

[purpleplexi]

Nowhere near. What you need is a major.