why is a 5W tube amp louder than a 20W SS amp

[Myaccount876]

Re: why is a 5W tube amp louder than a 20W SS amp

The official unit for vehicle engine power has been kilowatt here in europe for 40 something decades (I think) and were still talking about horsepowers too.

And that's probably only because the US still uses horsepower, so US owned brands (which is a lot of brands) end up using a unit so outdated that it used to mean literal horsepower - as describing the power of trains in terms of using horses to move a vehicle. What's ironic (from today's perspective) is that a man named James Watt (yes, the MKS unit is named after him) came up with the term horsepower.

 

[ehdwuld]

Re: why is a 5W tube amp louder than a 20W SS amp

40 decades is 400 years

Just saying

 

[beaubrummels]

Re: why is a 5W tube amp louder than a 20W SS amp

My tube amp runs on 30 horses, but 30 horses can run over my solid state amp any day.

 

[Myaccount876]

Re: why is a 5W tube amp louder than a 20W SS amp

My tube amp runs on 30 horses, but 30 horses can run over my solid state amp any day.

That’s roughly 22,000 watts, which is about a quarter of a Marshall Major’s power rating.

 

[Jacew]

Re: why is a 5W tube amp louder than a 20W SS amp

And that's probably only because the US still uses horsepower, so US owned brands (which is a lot of brands) end up using a unit so outdated that it used to mean literal horsepower - as describing the power of trains in terms of using horses to move a vehicle. What's ironic (from today's perspective) is that a man named James Watt (yes, the MKS unit is named after him) came up with the term horsepower.

US brand vehicles sell so little here I don't think that has anything to do with it. We have used term horsepower (hevosvoima) as well, and it has just sticked.

 

[ItsaBass]

Re: why is a 5W tube amp louder than a 20W SS amp

The main difference is probably the speaker/cab setup on each amp. E.Q. differences and compression differences can effect the apparent loudness too. There also isn't a huge theoretical difference in volume between a 5W and a 20W amp, even with all other variables eliminated.

 

[Jacew]

Re: why is a 5W tube amp louder than a 20W SS amp

...There also isn't a huge theoretical difference in volume between a 5W and a 20W amp, even with all other variables eliminated.

Good point. Comparing 5w and 15w tube amp, the difference is mostly just how "big" it sounds. There's not much difference in perceived loudness.
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[GilmourD]

Re: why is a 5W tube amp louder than a 20W SS amp

Good point. Comparing 5w and 15w tube amp, the difference is mostly just how "big" it sounds. There's not much difference in perceived loudness.
i

True. To be twice as loud as a 5W amp you need 50W.

But also remember, as I said above (probably more than once), a tube amp's rating is clean. Crank the snot out of a 50W Plexi and really smack the front end and you'll probably get 90W out of the sucker. Crank a 50W solid state amp and you're getting 50W.

 

[dystrust]

Re: why is a 5W tube amp louder than a 20W SS amp

True. To be twice as loud as a 5W amp you need 50W.

But also remember, as I said above (probably more than once), a tube amp's rating is clean. Crank the snot out of a 50W Plexi and really smack the front end and you'll probably get 90W out of the sucker. Crank a 50W solid state amp and you're getting 50W.

A solid state amp will produce a little more wattage beyond onset of distortion, but quite likely less than a tube amp.

The other elephant in the room is the tube amp's output transformer which allows full output into any compatible speaker cabinet. A lot of SS amps are rated at 8 or even 4 ohms, meaning they're putting out as little as 1/4 rated wattage into a 16-ohm load.

 

[GilmourD]

Re: why is a 5W tube amp louder than a 20W SS amp

A solid state amp will produce a little more wattage beyond onset of distortion, but quite likely less than a tube amp.

The other elephant in the room is the tube amp's output transformer which allows full output into any compatible speaker cabinet. A lot of SS amps are rated at 8 or even 4 ohms, meaning they're putting out as little as 1/4 rated wattage into a 16-ohm load.

An impedance mismatch will lower output wattage with a tube amp, too.

 

[Jacew]

Re: why is a 5W tube amp louder than a 20W SS amp

An impedance mismatch will lower output wattage with a tube amp, too.

Though you should never have impedance mismatch in tube amp in the first place. Generally, when tube amp has different available impedance outputs, it does produce full power to that impedance it is rated for.

SS amps only have minimum impedance values for outputs, so you can use mismatched impedances, which would drop the output wattage.

 

[Godin15]

Re: why is a 5W tube amp louder than a 20W SS amp

I have a 35 watt SS that puts out as much volume as a 40 Watt tube amp I once owned heard no difference.

 

[guitfiddle]

Re: why is a 5W tube amp louder than a 20W SS amp

Though you should never have impedance mismatch in tube amp in the first place. Generally, when tube amp has different available impedance outputs, it does produce full power to that impedance it is rated for.

SS amps only have minimum impedance values for outputs, so you can use mismatched impedances, which would drop the output wattage.

You can only mis-match up in impedance on a SS amp. Going lower can fry the output transistors. Some tube amps, like my Music Man HD-150 have robust enough output transformers to withstand a mis-match of 100 percent in either direction.

 

[GilmourD]

Re: why is a 5W tube amp louder than a 20W SS amp

Though you should never have impedance mismatch in tube amp in the first place. Generally, when tube amp has different available impedance outputs, it does produce full power to that impedance it is rated for.

SS amps only have minimum impedance values for outputs, so you can use mismatched impedances, which would drop the output wattage.

Well, yes, but that's because the transformer presents the same impedance on the primary as long as the secondary is matched to the cabinet.

Now say you have a Marshall JTM45 with a 784-103 output transformer. The pair of 5881s or KT66s would "see" 8,000 ohms from the primary side as long as the secondary side matched the impedance of the cabinet. However, if you selected the 8 ohm tap on the secondary but hooked it up to a 1960A cabinet rated at 16 ohms then the tubes would see 16,000 ohms, which would decrease the total output wattage because the tubes are working harder to produce signal.

Fender amps generally don't have a selectable output impedance (at least their vintage designs) and a lot of them have really low impedance ratings. For instance, my old '66 Dual Showman expected 4ohms. I never had the original cab, just the head, and I ran it into a Peavey 412MS. Fortunately I read up on the amp and ran two speaker cables off the head into each stereo half of the cab for a total load of 4 ohms. I bet a lot of people would've just plugged into a 16 ohm 4x12 and wondered why it wasn't that loud and they went through a lot of tubes.

The same thing is happening with a solid state amp, but there's no transformer in a solid state device, thus no selectable secondary impedance.

 

[Jacew]

Re: why is a 5W tube amp louder than a 20W SS amp

Well, yes, but that's because the transformer presents the same impedance on the primary as long as the secondary is matched to the cabinet.

Now say you have a Marshall JTM45 with a 784-103 output transformer. The pair of 5881s or KT66s would "see" 8,000 ohms from the primary side as long as the secondary side matched the impedance of the cabinet. However, if you selected the 8 ohm tap on the secondary but hooked it up to a 1960A cabinet rated at 16 ohms then the tubes would see 16,000 ohms, which would decrease the total output wattage because the tubes are working harder to produce signal.

Fender amps generally don't have a selectable output impedance (at least their vintage designs) and a lot of them have really low impedance ratings. For instance, my old '66 Dual Showman expected 4ohms. I never had the original cab, just the head, and I ran it into a Peavey 412MS. Fortunately I read up on the amp and ran two speaker cables off the head into each stereo half of the cab for a total load of 4 ohms. I bet a lot of people would've just plugged into a 16 ohm 4x12 and wondered why it wasn't that loud and they went through a lot of tubes.

The same thing is happening with a solid state amp, but there's no transformer in a solid state device, thus no selectable secondary impedance.

Connecting speakers and amps without taking note of correct impedance is just stupid ignorance. Not just with guitar gear but with any audio equipment.

I'm aware that in some cases mismatched impedance may work with tube amps, but why to take the risk?

 

[GilmourD]

Re: why is a 5W tube amp louder than a 20W SS amp

Connecting speakers and amps without taking note of correct impedance is just stupid ignorance. Not just with guitar gear but with any audio equipment.

I'm aware that in some cases mismatched impedance may work with tube amps, but why to take the risk?

Some people just did it. Some people did it on purpose. Heck, Marshall didn't even optimize the primary side to what the tubes wanted to see. They just used what was available until later. Why do you think a JTM45 only really made 30 watts clean even though it had a decently high B+? KT66s and 5881s can dissipate 25W and 23W each respectively, so a pair could theoretically put out around 50W.

 

[Jacew]

Re: why is a 5W tube amp louder than a 20W SS amp

Some people just did it. Some people did it on purpose. Heck, Marshall didn't even optimize the primary side to what the tubes wanted to see. They just used what was available until later. Why do you think a JTM45 only really made 30 watts clean even though it had a decently high B+? KT66s and 5881s can dissipate 25W and 23W each respectively, so a pair could theoretically put out around 50W.

And that's why there is so much stories about how unreliable and expensive to maintain tube amps are...

That's interesting thing about JTM45. I haven't actually thought about that.

 

[NjuiMusic]

Re: why is a 5W tube amp louder than a 20W SS amp

cause science bro

 

[IMENATOR]

Re: why is a 5W tube amp louder than a 20W SS amp

Is there some different criteria used in measuring tube and SS amps? Or is my 20W amp just broken?

It is about measuring the output power being feeded at the speaker using a "test" signal. But "watts" alone is no longer useful, something like "RMS" or "peak" along the rating is absolutely important to understand the context of the test the vendor did. Also, speaker size and efficiency (sensitivity) makes a lot of difference, a small non efficient speaker in a 20 watt amp could easily be buried in the mix by a bigger and more efficient speaker in a 5 watt amp. Also the frequency eq of the amp makes a big difference, an amp with lots of mids could stand out in the mix (that may be good or bad depending on what the band and song needs) and you may not need to crank the volume while an amp with a more flat/balanced eq profile may need to crank the volume in order to stand out in the mix, a good example of this is the famous scooped mids for metal, nice in the bedroom but lost in a band mix, I have been there before.