Watts, are watts, are watts? ('Tube watts' and 'solid state watts')

Hi everyone

I've seen this mentioned several times already, on these Forums and other places. What's all the talk of 'tube watts' and 'solid state watts' about? Shouldn't a watt 'mean' the same thing whether one's talking about a valve amp, a solid state amp or a pedal-powered amp?

Could anyone explain this to me in simple terms? Thanks!

 

Tube amps generally clip more gracefully than solid-state amps.

 

Not really ... I mean, my 55 watt Ampeg B-25B bass head (all tube) I use in my Rush tribute band blows away the newer Ampeg B-15R (all tube as well) that is rated at 60/100 watts (switchable). Granted the cab I use with the B-25B is a 2x15" so I'm moving more air than the 1x15" of the B-15R, but the type of tube, its capacitance, etc., all color the sound and affect things. I generally find with tube stuff you don't need to crank to get the same volume.

 

THAT's what I'm asking about. Why is that? Compression?

 

See http://www.tabcrawler.com/articles.php?action=readarticle&articleid=66

As MMM said, it's largely to do with clipping/distortion.

 

Heh - Nelson Pass designs transistor amps... He regularly contributes to DIY mags with amp construction articles and writes clearly enough for non-engineer types like me to pretty much get what he sez...

 

My mind's a bit rusty (was lifting concrete all day )...wasn't Nelson Pass the designer of Threshold's amps, or am I thinking of another company?

 

Thanks, StyxCollector. The article pretty much cleared things up for me (thanks everyone else, too!).

So if I got it right, it basically has to do with the 'listenability' of the distortion from one and the other- meaning tube clipping is more 'pleasant' (or less unpleasant), allowing one to turn things up further before fatigue and unpleasantness set in?

 

Yes Rudy, That is Nelson. I've had Threshold's since the 70's.

 

That's the guy...

 

Cool. I don't remember what the amps sounded like, but when I was regularly cruising the high-end shops on Woodward, they were the coolest looking amps. Always wanted one but never had the $$$ to pull it off.

 

Heck - build yerself a Zen....

 

Yeah, I know what you mean. I had recently graduated form college and somehow fallen into a good but low paying job in pro audio. Audio was my life at that point in time, so I guess I had fairly warped priorities. I think my first Threshold was a 400A.

 

Nakamichi used Nelson Pass's "Stasis" topology as the foundation for their PA series amplifiers made in the late 80's and early 90's. I own a couple of them and they sound pretty good. Stasis topology reduces "negative feedback".

Evan

 

I also have a Pioneer SX-6 60 Watt receiver from the early 80's that used Nelson's 'synchro bias' which offered many benefits of class A circuitry without the usual high idle current. IIRC, he licensed this technology and a lot of Japaneese companies used it. I think Nakamichi was among the first to do so.

I guess history will put him up there with some of the great amp designers of the 20th century.

 

Steve, are you saying that speakers with a lower sensitivity are of an inherently inferior design compared to speakers having a high sensitivity?

 

Nelson has designed some powerful amps - gotta drive those watt hungry acoustic suspension speakers... http://www.passlabs.com/products.htm

 

For the Pass DIY approach: http://www.passdiy.com/

 

Hey, THAT's cool!

 

I'll bet it runs hot!

 

Runs as hot as my class-A zero negative feedback BEZ T3B 300B SET amp! But what a sweet sounding first watt it has (with only seven more for headroom). My 98.5dB Klipsch Cornwalls don't mind cranking out 100dBs worth of distortion-free pipe organ music in my listening room...guess that first good watt is all that matters, eh?

 

jt1stcav,

Lakeland eh? I've been through your area. I've been doing a call center in Ocala this year, and I've been there 8 times. I love horse country!

 

Well then, you'd like Lakeland...

Here's a pic of my back yard facing a horse pasture...it's really nice!