Noob Tube Question (seriously)

[TheDHndrsn]

I have always been confused by something. Well, many things but this one applies to stereo. I lived through the transition of tube to solid state, albeit young. Now that I have rediscovered my audio soul, I find myself wondering yet again about the same, unanswered question.

When you think of tube amplifiers, power (output) is typically single or double digit wattage. For example, a YouTube video watched a few days ago included a voice over discussing a 40wpc tube amp. That comment struck me two ways. First, that someone would hold 40wpc in such high regard. Second, that I, myself hold a 40wpc tube amp in high regard.

A big solid state amp to me is 200+wpc.

Is output measured differently in tube versus solid state amps? My research to answer this question does not suggest a difference.

Other than the obvious use of transistors, is there something about pushing electrons out of a tube amp that makes 40wpc competitive with (e.g.) 200wpc through a solid state amplifier?

What about speakers? Is it possible to run a pair of 8ohm, 150W RMS speakers with a 40wpc tube amp?

If that is not the case, were tube-era speakers more efficient and less power hungry than today's speakers.

Questions. Questions.

Can anyone help me put this in perspective?

Thanks!
Dave

 

[rogerh113]

I can only provide my experience. I can drive a pair of Klipsch Forte speakers, which are pretty high efficiency speakers, with probably about 35 tube watts on a 50 watt per side amp (some headroom left over and distortion not setting in quite yet). This is in a fairly large room and what I consider comfortable, but not loud, volume. I really enjoy tube amps, because of the sound, and am currently running a SET amp. Can't imagine going back to solid state. You can read about folks enjoying a 6 or 8 watt per side SET, and I just don't know how it is possible, unless it is a very small room, at low volume, with very high efficiency speakers (or on headphones). I have found that if you have sufficient power, the sound is glorious - if you don't then the bass is virtually non-existent, and you are limited to light jazz or quiet quartets. There is a reason why people are always making excuses for very low powered amps, and that is because they need to. I understand, because reasonable powered SET amps are VERY DIFFICULT to put together. Fortunately push-pull amps are easier to get power out of, but on the Klipsch I was running a Primaluna Prologue at 35 watts/side, and it really was inadequate (for my listening room and speakers), the bass was feeble and I think I was pushing it into distortion I was so close to the limits. I am running a 50 watt per side SET now, and it is stunning - just absolutely blows away the Primaluna. Jazz, rock, classical - it is all full bodied and stunning. Do I sound happy - yes!!

I think that if you can get around 50 real tube watts with reasonably efficient speakers, then you can listen to rock, jazz, classical, whatever you want and you will be quite satisfied - with less then you are in a small room with very efficient speakers listening to specific types of music, or severely compromised.

Regards -- Roger

 

[gadget73]

Power is measured in exactly the same way. 20 watts is 20 watts no matter what makes it. You might hear about "tube watts" but thats pretty bogus. You can get tube amps to run closer to their max rated power before they distort in a horrible sounding way, but thats really it. They don't clip as hard or as suddenly as solid state does.

The reason the wattage ratings are down is simply because its too blasted expensive to make extremely high power tube amps. You end up with very large, heavy, and expensive transformers to get it done. There have been some made that hit around the 100 watt per channel mark but its not nearly so common as it is with solid state. Bigger ones also exist, but generally you're out of the consumer market at that point and into stuff that looks more at home in Frankenstein's lab. Just for yucks, here's one that is claimed to make 1kw of output. This is one channel.

http://www.chambonino.com/construct/const9.html

Even if you're not a super technophile, have a gander at some of the numbers tossed about in there. 2.5kv on the plates of those tubes is nothing to snarf at.

Old speakers were usually more efficient. Kind of had to be to make a lot of sound with small power. The wattage rating doesn't matter so much as the efficiency rating, though generally the high efficiency speakers don't tend to be rated for very high wattage.

I'm running 15 watts per channel on speakers in the high 80s for efficiency. Right now its Bozak 401's, the other pair out here are JBL L-40. I can get more than adequate sound levels out of that, but my listening levels tend to be low and I'm not real far from the speakers.

 

[primosounds]

I have always been confused by something. Well, many things but this one applies to stereo. I lived through the transition of tube to solid state, albeit young. Now that I have rediscovered my audio soul, I find myself wondering yet again about the same, unanswered question......Can anyone help me put this in perspective?

Thanks!
Dave

One aspect of reproduced sound that you did not address is that for the most part when you are listening to whatever music you enjoy, the music being reproduced requires only a few watts of power. In most home systems less than 5 watts will achieve a very satisfactory sound level. It is the quality of the first few watts that sets tube amplification above the sand amps. With fewer parts in a simpler circuit, a tube amp can be very linear in the critical mid range audio frequencies. As we get older our tastes are more refined and we can appreciate music that is not pounding through our body like a wave smashing you in the shore break. The somewhat juvenile attraction of "bigger, faster, louder" gets tiresome and is ultimately unfulfilling and unsophisticated.
And don't forget that the warm and soothing glow of the vacuum tubes rekindles our genetic memories of the safety and cheer of the fireplace after a long day of hunting and gathering. Looking at a solid state amp doesn't make me warm and fuzzy inside. How can you not be enchanted by a working McIntosh 240 with all the filaments from its 12 tubes glowing softly with their yellow light. And if you get one of those Audio Research Reference 750 with its 16 kt88 power tubes you could literally plop it in the center of your living room in the middle of winter and make 'Smores with your kids! Cheers, Primo

 

[Destructor]

Also many older SS amps and receivers only fell into the 30 to 75 watt range but they were rated continuous power, many of the cheaper box store receivers today are rated only at peak power. An early 70’s 50 watt SS receiver was quite heavy.

 

[Dswankey]

when you are listening to whatever music you enjoy, the music being reproduced requires only a few watts of power. In most home systems less than 5 watts will achieve a very satisfactory sound level. It is the quality of the first few watts that sets tube amplification above the sand amps. ............... The somewhat juvenile attraction of "bigger, faster, louder" gets tiresome and is ultimately unfulfilling and unsophisticated.

Outstanding, I've had this explained to me on numerous occasions by folks with engineering backgrounds who also enjoy audio. We always have a good chuckle when someone brags about about there 100 wpc + amp or there need for more wpc. The human ear can only stand so much and if I'm not mistake the whole monster wpc thing was more for marketing to appease the "mines bigger" & "bigger, faster, louder" crowd.

 

[N8Nagel]

Outstanding, I've had this explained to me on numerous occasions by folks with engineering backgrounds who also enjoy audio. We always have a good chuckle when someone brags about about there 100 wpc + amp or there need for more wpc. The human ear can only stand so much and if I'm not mistake the whole monster wpc thing was more for marketing to appease the "mines bigger" & "bigger, faster, louder" crowd.

Well, there is *some* justification for more powerful amps... Back in the tube era where 15-30WPC amps were the norm, full-range speakers often either weren't truly full range (mostly rolling off the bass at 40 Hz or even higher), or were really large (think Bozak Concert Grand, Wharfedale W90, various Klipsch models, etc.) The introduction of solid state amplifiers made it possible to have more power in your living room without your amplifier doubling as a hot dog cooker. What this meant was that less efficient speakers could be used, and speakers like the AR3 etc. traded off sensitivity for more bass extension in a smaller package. This was a Good Thing when one person in a house wanted good sound (and most importantly, good bass) but others might not be so accomodating to a living room full of huge walnut cabinets...

Now I agree, even with small, inefficient speakers, loud listening levels, and a healthy allowance for headroom, there is some point where numbers start being for bragging rights only. But I don't consider a 100WPC amp completely silly when paired with SS era acoustic suspension type speakers... maybe a little overkill, but not as ludicrous as it sounds just from the perspective of "well, my Wharfedales sound great on 30 WPC so I don't see the big deal..."

 

[s-petersen]

The only thing extra power is good for is "feeling the bass in your chest" I rarely push the MC75's above the 30 watt level in normal listening.Once in a while I like to crank it.It's like having a powerful car,you don't always use the power,but sometimes...you do.

 

[larryderouin]

Exactly Scott! Why have a F350 DUALLY Diesel when the only thing you are doing is hauling kids, or the occasional load to the dump when a V-6 S-10 will do the same thing. Bragging rights, is all.

 

[Dukiedook]

Exactly Scott! Why have a F350 DUALLY Diesel when the only thing you are doing is hauling kids, or the occasional load to the dump when a V-6 S-10 will do the same thing. Bragging rights, is all.

And when the wife and kids are gone and you want to crank that song to 11 and feel like the Maxell guy.

 

[TheDHndrsn]

... This is one channel. ... Even if you're not a super technophile, have a gander at some of the numbers tossed about in there. 2.5kv on the plates of those tubes is nothing to snarf at.

Oh my Lord ... that amp just blows me away. From the responses here I have learned a few things not appreciated previously. First, that tube systems take so much power. I did not understand this about them. Clearly a driver for the solid state revolution. Second, speaker efficiency is poorer today than in tube days. While this was my working theory on tube amplifier setups, reading comments to this end puts a lot of things in perspective.

To the point of needing less than 30wpc to appreciate music, I am in complete agree with this. As with the Dually or in my case a GT, 99% of the time nothing is smoked. Then there is that 1% to get your day going. That said, it brings up a point about power that I did not see mentioned. Dynamics.

I enjoy dynamic audio whether progressive rock or classical. My experience always has been the more power / headroom the better the sound. Then again, a lot of that has to do with the speaker. Some speakers sound better with a lot of watts while other speakers sound best at low volume, or at least that is my experience. Are tube amplifiers faster and more responsive thus needing less power to deliver the same dynamics in the audio?

Clipping and linear range is also something to sink my teeth into. Had not known about this but it intuitively makes sense. I think I must go build me a tube amp, or a pair of them, and see where it takes me.

Dave