Apples to apples? Tube vs. Solid State…

Gary Lee Gimble · From: Fredericksburg, VA.

Tube watts verses solid state watts, are they the same output in volume, tone, presence and anything else I may have missed? Apples to figs?

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Generally, watts are watts. However, tubes can be pushed further into distortion than transistors because the distortion is more pleasing. Therefore a 50-watt tube amp may be capable of significantly more than 50 watts of usable power, while the 50-watt solid-state amp isn't. Once transistors start to clip, the sound is not pleasing, and they often have protective circuitry to protect the transistors (which are sensitive to heat). Tubes like heat, and generally, the hotter the better as far as performance goes. Of course, you do eventually reach a point of meltdown, but it's far more gradual than with solid state gear. I'd say a tube amp rated at 100-130 watts would probably perform similarly to a solid-state one rated at 150-200. Of course, you're only getting close to these figures when the amp is wide open, the pedal is all the way down, and you're playing very forcefully. Most steel players seldom get above the 25-50 watt range, regardless of what amp they're using.

As far as presence and tone, I think that's largely due to the settings and capabilities of the amps. Although there is a dynamic difference in the sound of tubes and transistors, that difference is very slight until you get into distortion. Guitar players happen to swear by tube amps because almost all of them like varying measures of distortion (which they use to mimic sustain). Steelers, on the other hand, generally like clean and pure tones, and they use a volume pedal for sustain, so most steelers are quite happy with solid-state amps.

David Doggett · Posted 22 Dec 2008 7:47 pm

I think Donny has it about right. In my experience, a 100-135 watt silver-face Twin will be about as loud for steel as a 200 watt Peavey NV400. And this is for Twins setup to play clean to the top. They will not give what guitar players consider distortion even maxed out with the volume pedal stomped. However, near top volume I imagine that if you measured harmonic distortion near maximum volume it would be around 5% on the Twin, maybe even more. It would not be blatant distortion, just a nice sweet, warm bloom, and would still be what guitar players consider "clean." In fact, a Twin probably has a few percent harmonic distortion even at lower volumes. But it is the kind of musical, rich tube harmonic tone many of us love. The Peavey solid-state amp might have only around 1% harmonic distortion throughout most of its range. It is perfectly clean, but to me a bit sterile sounding. At its top volume it might begin to have a little more distortion. It would be less harmonic distortion than the Twin at top volume, but has what I call a brat or f*rt sound - not so good.

So what I'm trying to say is that if you could keep both amps in the range where their harmonic distortion is similar, watts are watts. But in practice, we let tube amps have more harmonic distortion, and so can get more usable volume from them than a SS amp rated the same output (but with less harmonic distortion). In other words, it's not apples to apples, because the harmonic distortion is different.

Bob Hoffnar · From: Austin, Tx

Gary,
In my experience the whole how many watts thing seems wildly variable. I've been playing through 2 different old Princetons that are rated the same and one is way louder than the other. The solid state thing is weird too. I tend not to like solid state amps but I have an old Standel with no tubes anywhere that is responsive and sounds warm and open.

The bit about clean headroom being the main issue with amps for steel doesn't mean much to me. The reason I like some amps is because of there response to subtle differences in articulation. Class AB tube amps tend to work best for me.
_________________
Bob

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

There are a ton of variables that go into what I call "apparent loudness" of an amp.

I think Donny's in the ballpark on the distinction between the differences in ability to push a solid-state amp versus a tube amp. One can usually push a typical tube amp quite a lot harder than the typical solid-state amp partly because the tube amp slides into saturation much more gradually. Depending on the circuit, the pushed tube amp sound tends to stay together better, while the solid-state sound typically gets obnoxious very quickly.

But there are many other wrinkles and differences. For example, on a modern Peavey solid-state pedal steel amp, when the amp is pushed hard, the DDT compression kicks in. I really like this, because it allows me to really kick the amp pretty hard if I want to and it gives a fairly clean sustain. The volume increase is limited, of course, but does give a bit more apparent volume to my ears. On a comparable amp without compression, the sound can get pretty ratty when pushed hard like this.

Another difference is that tube amps typically use output transformers, while most solid-state amps are directly coupled. There are some exceptions - I've played some solid-state amps coupled via output transformer - for example certain old Sepulveda-made Vox solid-state amps. Some of these also had limiter circuits built in. I had an old Vox Viscount that was just deafening, and I was surprised that it sounded pretty durned good - the rep is that these were junk, and I disagree.

Of course, another critical issue is speaker efficiency. What one actually hears is the speaker(s), and the ability of these to convert an electrical power signal into sound waves is hugely important.

Another issue is the bandwidth of the program being amplified. The way a lot of pedal steel players play, the instrument tends to place pretty significant demands on an amp for good articulation across a wide bandwidth. At low volumes, a small tube amp may work just fine, but fall apart when more volume demands are made.

So to me, a lot of the generalities people talk about are fine as generalities. But one has to get down to cases, and the only way I know how to evaluate that is to listen to various amps and see what I like. Sometimes I am very surprised at what works for me and what doesn't.

Like Bob, I generally prefer class AB amps. Class A amps have a very interesting, harmonically-rich sound, and are good for certain things. But for the kind of clarity I usually like - a strong, snappy fundamental with less emphasis on harmonics - I generally prefer AB for most things. This is far from universal, and I think how one plays affects this a lot. Watching Duke Levine playing his Tele through a Vox AC-30 in October and sound almost exactly the same as when playing that same Tele through his Magnatone 280 or an old Ampeg in July made me scratch my head a bit.

Anyway - I think this is hugely subjective and style-dependent, so YMMV.

Gary Lee Gimble · From: Fredericksburg, VA.

On numerous occasions, I have heard comments like, “Yeah, those are Peavey watts, solid state, not true watts.” Of course, these commentators may know slightly more than I do when it comes to electronics, that being, the location of an on and off switch. Regardless, I felt a need to query this topic of tube verses solid state wattage after reading what Randy Beavers posted on his Myspace “new amp” blog. His new light weight puppy sports excellent therapy for one’s back and at the same time, pumping out 500 watts. Donny, are you suggesting that Randy will only tap a max of 10% of his available horsepower? When I first read his blog, I thought Randy may have threaded a 70 gauge string equipped with a boowah pedal on his E9 neck. Not that he would need it, but after all, 500 solid state horses would complement a 70 gauge wire with plenty left over.

Anyway, there is more to this topic. My Session 500 sustained a terminal injury from the heel of my boot. All was disposed of excluding the speaker which now has a new home in a freshly built enclosure, and she is super light. I have also been considering an economical, alternative mode of transportation, given the volatile energy market. Most of my gigs, when ever they materialize, require a long drive. So I want a small integrated power amp, plug and play kinda deal that doesn’t require much thought. I don’t want a rack with multiple pieces and more knobs than my current aptitude can handle. I don’t want a NV 112 either. Most folks that I have seen use them, have a buffet of effects at their disposal. Very rarely, if at all, have I seen anyone just plug straight into one and sound like a million dollars. I just want simple stupid and sounds good….

Larry Scott · From: Virginia, USA

Ehheehummmm

WEBB Winking

I think you might be able to purchase just the chassis from Mr.Bradshaw.

Matti Viitala · From: Etelä-Pohojammaa, Finland

Dear Sir Gimble.

I've done some gigs with my Fender Hot Rod DLX (20 to 1000 people in audience) with my six string and i love that tube amp and its sound. But ewery time it has been miked to PA, so i've never had a heard that amp with volume knob turned more than 4.
So I think that with a good PA-system and a Pignose amp You do better than 99,7% of us.
_________________
Bass player works just like a drum, you just need to hit it.

Dan Tyack · From: Olympia, WA USA

My rule of thumb is that you use the most powerful solid state amp that you can afford, and the lowest watt tube amp that can handle the gig.

As a rule of thumb it's at least 2 to 1 (you would need to have at least twice the solid state wattage compared to tube to handle the same room).

Most solid state power amps sound best when they aren't even breathing hard, while tube power amps sound best when they approach their limits.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Greg Cutshaw · From: Corry, PA, USA

A one volt peak sine wave into one ohm of resistance produces 0.5 watts of rms power (.707vrms * .707vrms)/1ohm

A one volt peak square wave into one ohm of resistance produces 1.0 watt of rms power (1vrms*1vrms)/1 ohm.

The more distortion you introduce into a sine wave by clipping it, the closer to a square wave it becomes, and the more power it produces. As long as this distortion is pleasing to the ear, you can crank an amp into distortion and get a lot more power out of it. Of course doubling the power, is not a huge gain in decibels so maybe some other phenomenom is present here, such as the high tube amp gain that is typically present even at low volume settings (depending on the taper of the volume pot). The higher gain and feedback also allows for more sustain which creates more output power per note by sustaining each note for a longer period of time.

Greg

Larry Scott · From: Virginia, USA

b0b · From: Cloverdale, CA, USA

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Perceived volume has very little to do with real power. This is because high frequencies actually take so very little power to reproduce (on the order of only a few watts). It's the lows that take tons and tons of watts. If you don't play with a moderate amount of lows, and if you don't want "fatness" in your sound, you really don't need 200 watts. (This is why most lap players are quite happy with a small amp - none of them play with any real bassy sounds on the low strings.) On the other hand, you don't see bass players en masse miking 25-watt bass amps. That's because it's simply not enough power for their requirements. Many lead players might consider a Vox AC-30 as "too loud", but you'll find very few pedal steelers content with less than 100 watts.

High power isn't about volume or loudness, it's about tone. Shocked

Lynn Oliver · From: Redmond, Washington USA * R.I.P.

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