How much louder is a 50 or 100 watt JMP vs an SV20?

1234_thumbwar

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I know amplifier wattage, headroom, and volume are peculiar subjects to be objective about but I'm sure someone on this sub has two or three of these amps to compare. I've played through a couple 1959s before but never dimed like I can with my SV20. I know the SV20 is loud but I regularly get away with playing it at volume at home on 20 watts and I can even play with family in my apartment on the 5 watt setting.

I know good and well I'm not playing 50 or 100 watts at home dimed with or without family over because I have a 50 watt JCM 800 that will get me some noise complaints from neighbors with the master past 8 or so but I can play for as long as I can tolerate it at 5 or 6 on the volume and the gain as high or low as I like. I'm not typically the kind of player to crank a plexi so I wouldn't need to with a big one but I do wonder how much louder a jumpered 50 or 100w is compared to the 20w. Do the bigger ones just break up at a significantly louder volume because of the headroom? I've noticed that there's more bloom or room for each note to fill out the room on the 20 watt setting vs the 5 watt setting so would a bigger plexi just mean more bloom for lack of a better word? Having experience with a small plexi has stirred up some temptation to see what the bigger ones are all about. Especially if everything leads me towards a Superbass, 1986, or a Hail Mary with a JTM45/100 or JTM50

I also bought an attenuator shortly after getting my SV20 but I frankly haven't had a need for it yet. If I get a 50 watt JMP the attenuator will be good for it but 100 watts would melt the one I bought just in case anybody says I'm going to need one
 

V-man

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Here is the thing: You already know the difference for your purposes, since you already have a 50w JCM and a 20w SV.

We can say 20 (rounded up) is 1/2 the perceived volume of a 50w or -3db by comparison. Then there are the RMS and SPL rabbit holes of loudness one can delve into, but the reality is you already have the idea of how much louder your pushed 20w is compared to your pushed 50w.

If the question is “will I need an attenuator for a 50w/100w Marshall based on my experience above?”, then the answer is yes in all likelihood. A pushed NMV will seem at least as loud as the pushed 50w JCM..
 

1234_thumbwar

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I have an SV20H and a 1987X.
In my home jam room which is about 11x16 I can tolerate the SV and it is LOUD! The 1987X, ear splitting, painful to say the least.
So I guess the difference would be going from loud amp in the room to an amp that's too loud to be in the room with? I wish I had a decibel meter to see what these amps are really putting out when clean vs breaking up
 

V-man

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I used to run my 1959RR wide open in the office (after hours) and found it more ideal to be in the next room. I also had a 1992 (JCM -different animal from JMP). That amp (unlike my RR) was all headroom. It was pure clean until @8. One amp was automatically massively-loud out of the box. The other had to be that loud if I wanted natural breakup.

Attenuation is the best/more important purchase for a NMV next to a speaker cabinet.
 

1234_thumbwar

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Here is the thing: You already know the difference for your purposes, since you already have a 50w JCM and a 20w SV.

We can say 20 (rounded up) is 1/2 the perceived volume of a 50w or -3db by comparison. Then there are the RMS and SPL rabbit holes of loudness one can delve into, but the reality is you already have the idea of how much louder your pushed 20w is compared to your pushed 50w.

If the question is “will I need an attenuator for a 50w/100w Marshall based on my experience above?”, then the answer is yes in all likelihood. A pushed NMV will seem at least as loud as the pushed 50w JCM..
I guess the question is at what volume do the big ones break up compared to the 20 watt with the difference in headroom and how does the pick attack differ with the additional headroom.

I don't know how much louder the point of breakup is with a 4 hole amp because my 800 has a master volume and I guess that's what I'm trying to figure out. How does the additional headroom affect the volume I have to play at for a bit of power tube saturation. Even if I turn the gain down with the master up an 800 still feels and reacts differently imo
 

1234_thumbwar

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I used to run my 1959RR wide open in the office (after hours) and found it more ideal to be in the next room. I also had a 1992 (JCM -different animal from JMP). That amp (unlike my RR) was all headroom. It was pure clean until @8. One amp was automatically massively-loud out of the box. The other had to be that loud if I wanted natural breakup.

Attenuation is the best/more important purchase for a NMV next to a speaker cabinet.
That's what I did with my 800 whenever I decided to run it loud, leave it in a room by itself with the door cracked and let it rip with my telecaster. I've got an attenuator on the way but I bought it for the SV20 just in case I needed it. It's rated at 100 watts so it's only good for a 50 watt or less but it'll probably be a few months before I decided to get another amp. I'm just pondering and thinking about if I should trade my 800 for a JMP to pair with the SV20
 

Matthews Guitars

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The ear perceives loudness differently according to the waveform. 100 watts RMS true clean power, undistorted sine waves, sound quieter than the same power signal that's complex, distorted, and full of harmonics.

Power to dB conversion requires some math. But here's the cheat codes for it:

A change of 2 dB: Multiply by 1.7.
A change of 3 dB: Multiply by 2.
A change of 10 dB: Multiply by 10.

So a volume change of 15 dB would require an increase in power by a factor of 13.7.

So, if one watt delivers 100 dB at the front of the speaker, than 13.7 watts will deliver 115 dB.


Here's a great resource to learn all about it.:

 

1234_thumbwar

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The ear perceives loudness differently according to the waveform. 100 watts RMS true clean power, undistorted sine waves, sound quieter than the same power signal that's complex, distorted, and full of harmonics.

Power to dB conversion requires some math. But here's the cheat codes for it:

A change of 2 dB: Multiply by 1.7.
A change of 3 dB: Multiply by 2.
A change of 10 dB: Multiply by 10.

So a volume change of 15 dB would require an increase in power by a factor of 13.7.

So, if one watt delivers 100 dB at the front of the speaker, than 13.7 watts will deliver 115 dB.


Here's a great resource to learn all about it.:

I appreciate the info and I’ve got some reading up to do, thank you
 

V-man

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I guess the question is at what volume do the big ones break up compared to the 20 watt with the difference in headroom and how does the pick attack differ with the additional headroom.
Now this is an entirely different matter of discussion.

As I said before, my 1959RR is wildly loud at any volume- full hard rock breakup at 3-4 and full volume at 2. I am well aware 1959s are loud, but the comments I have read about mine suggest it is LOUD among loud amps, and it makes me believe the volume taper is different and more aggressive compared to the vintage amps. Regardless of the volume and breakup, it is the most touch-sensitive amp I own and light attack at HUGE volume whereas a power chord at the very same volume turns into The Who.

My 1992 was completely clean and required full pick attack at full volume to get any breakup on it at all.

My JMP-1 wasn’t used much at all for cleans. It was gainy but I am pretty certain it had minimal headroom.

This is not a question of 20w vs 100w. This is a question of the circuit (which includes wattage) but even among JMPs of the same wattage, different characteristics exist amidst the models regarding headroom, sensitivity and volume taper.
 

jeffb

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I guess the question is at what volume do the big ones break up compared to the 20 watt with the difference in headroom and how does the pick attack differ with the additional headroom.

I don't know how much louder the point of breakup is with a 4 hole amp because my 800 has a master volume and I guess that's what I'm trying to figure out. How does the additional headroom affect the volume I have to play at for a bit of power tube saturation. Even if I turn the gain down with the master up an 800 still feels and reacts differently imo
This varies amp by amp when we are talking old ones.

I've played original NMVs that were on 1 and quiet, and by 2 they were loud and by 3 they were killing your ears. And I've played other ones that were much more gradual in build up of gain and volume. Some (as mentioned) have big headroom and remain very clean until you get way up on the dial.

If we are talking newer Marshal reissues, my experience is they are starting to get loud fairly quickly, but breakup occurs more gradually..

What type of pickups makes a big difference - NMV amps are way more sensitive to how hot (or not) your pickups are. If you are playing vintage strat and tele singles, your amp will not give up the goods until you are really pushing, and conversely you might be getting a nice light crunchy sound using a SuperD or Duncan Custom at fairly low on dial.
 

Matthews Guitars

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V-Man, your description of your 1959RR almost is a perfect description of my 1959 that was made in 1973. Except that it doesn't reach full volume at 2. That happens around 3. If you dig in and play hard it'll begin to overdrive as low as 2 on the volume control. (high sensitivity input) Beyond 3 it adds more power stage crunch.

But even at full volume, you can still play clean just by backing off your touch and playing gently. Or turn the guitar volume down.

My 1969 Plexi is similar, but it has a slightly different sound to it and doesn't go quite as loud.
 

scozz

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The old rule of thumb is, (or was),.… double the wattage increases the volume by 3 db. Also, to have an amp that is “twice as loud” as another amp, it would need to be 10x the wattage. So to be twice as loud as a 50 watt amp, you would need a 500 watt amp. Generally speaking of course.
 

1234_thumbwar

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The old rule of thumb is, (or was),.… double the wattage increases the volume by 3 db. Also, to have an amp that is “twice as loud” as another amp, it would need to be 10x the wattage. So to be twice as loud as a 50 watt amp, you would need a 500 watt amp. Generally speaking of course.
So does plate voltage play a part in how loud they are as well?

I feel like I’ve read threads where people say their 50 or 100 watt is at 450 or 500v while the SV20 is at around 250 or so. I’m not sure if I’ve misread what was linked in this thread earlier but I’m confused if this also plays a part in how loud the big ones are
 

MarshallDog

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Not very much based on the relationship between wattage and dbs! A google search will explain it in detail. A few differences, a 100w will have more clean headroom at the same volume settings, it may have more solid bottom end and it will cost you double to retube the 100 watter!
 

JohnH

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I've got a sound clip that may help illustrate the differences in levels. I did this when I testing my attenuator design. What it covers is a looped riff which repeats. Every two cycles it gets 3.5db louder, so as it gets up to high level, you can appreciate to some extent, the difference that such a step makes.




(hmm...seems the new software is turning the link that I copied from my attenuator thread into something that doesnt work... Its in Post 1 of this

https://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/ )

By comparison, the step from 20W to 50W is 4db and 50 to 100 is 3db, so these 3.5db steps are very close.

Of course, what you cant get from such a clip is how stupendously loud full volume can be.
 
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1234_thumbwar

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I've got a sound clip that may help illustrate the differences in levels. I did this when I testing my attenuator design. What it covers is a looped riff which repeats. Every two cycles it gets 3.5db louder, so as it gets up to high level, you can appreciate to some extent, the difference that such a step makes.




(hmm...seems the new software is turning the link that I copied from my attenuator thread into something that doesnt work... Its in Post 1 of this

https://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/ )

By comparison, the step from 20W to 50W is 4db and 50 to 100 is 3db, so these 3.5db steps are very close.

Of course, what you cant get from such a clip is how stupendously loud full volume can be.

I found the clip you were talking about in that thread about attenuators. I can get away with 20 watts cranked at home but 50 watts all the way out was a bit too much for my neighbors last time I cranked my 800 so that extra 4 db might be the difference for me. I guess this is kind of the perfect situation for an attenuator just to knock 3 db or so off if I come across an old 50 watt that I can agree with. I don't think I'll ever be in the market for 100 watt anything though
 

V-man

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I think one of the takeaways is if you can fully avail yourself of a 20w wide open, then you can use a 100w. The bigger problem is ppl who can’t accommodate a 100w so they think a 10-40w is the solution, and surprise… that’s too loud as well.
 

Michael Roe

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So I guess the difference would be going from loud amp in the room to an amp that's too loud to be in the room with? I wish I had a decibel meter to see what these amps are really putting out when clean vs breaking up
In my case, yes! It does though depend on the size of room you are in. My room is very small.
 

1234_thumbwar

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I think one of the takeaways is if you can fully avail yourself of a 20w wide open, then you can use a 100w. The bigger problem is ppl who can’t accommodate a 100w so they think a 10-40w is the solution, and surprise… that’s too loud as well.
I guess I wouldn't ever be able to crank the 100 without an attenuator but with jumpered channels I guess I could get a nice crunch or overdriven sound with the amp in a room by itself. It just seems intimidating to go from 20 to 100 and then I'd have to get a 4x12 because I like greenbacks and that means a lot more air moving. I think 50 watts might be my happy place just because I can't find the space to fit a 4x12 let alone let it roar like it should. I have the sv20c and the biggest cab I've played it through was the 2x12 combo my 4104 is in
 


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