Sonic qualities of SET output tubes?

kdude66 > All the Linear tube audio gear is greatly influenced by David Berning and has his blessings Offcourse.

Blindjim > ROTFLMAO 8-)….. THANKS. VERY COOL, Where is LTA home base?


Inna > Please listen to Ypsilon; Gryphon Diablo and the 300.

Blindjim > thanks. I went and read the Fremer article after much trouble to do so. Liked what was said about the really expensive amp he had some primary input tube or bias issues. There are a couple really valid concerns for me with the mentioned amps herein.

Barring it’s a bit off topic, First, is money. Second is value in the secondary market. Yes. These are reputedly ‘destination’ ish items. But I’ve been around long enough to know I need to be around a lot longer, and very few presupposed ‘keeper’ anythings seldom become exactly that.

Lastly, its getting to hear any of them in any suitable setup without contracting guides, bearers and a Shaman to get there.


Atmosphere > Once you settle on a particular power tube type, then you sort out which brand of that tube to get. The choice of power tube type is heavily dependent on which speaker you get!! …or want.

A good system should **never** sound loud!

the speaker simply has to have the efficiency such that you don’t exceed about 20% of full power of the amp you have in mind.

Blindjim > Much respect and immense gratitude for the knowledge. Truly.

However…. Perhaps it was the choice of words used. Not sure. Maybe this is theoretical only.

Employing the philosophy that an amp should not or perhaps never, exceed 20% of its rated output to adequately propel the speakers SPL to satisfying levels gives me great pause.

In a perfect world? This means your 60wpc monos are actually 12wpc monos if applied correctly??

Superficially, it should give many audiophiles great pause now, or going forward an entire resetteling of standard system building notions and themes in tact presently, and from years back. Well, from the ‘90s anyhow are suddenly unceremoniously banished forthwith.

Under your inference, we should now consider the new shiny expensive 100wpc amp is only a thoughtfully applied 20wpc amp is gonna be a real tuff pill to swallow. It’ll break a lot of hearts. Not to mention wallets as folks begin scrambling for new larger amps, or easier to run speakers. Or both.

Still more pointedly, the overwhelming majority of loudspeaker makers should be shivering in fear of such a notice for amenable amp & speaker combos has abruptly evaporated until they redesign things so their 83 to 92db units get with Jenny Craig and reduce their dudgeon dwelling impedance curves to slimmer sleaker heights, whiole at the same time increasing sensitivities into triple digits.

20% of rated power. Whoa! That’s a pretty strong edict. But OK. I’m probably missing something important.

Lastly, that good sounding rig ought never sound loud really jiggles my jelly. “…. Hath sounds to soothe the savage beast”.

Now there is a decided dissimilarity between a speaker playing loudly and a speaker ‘shouting’.if that was the actual meaning in your remarks on what a rig should never sound like.

Occasionally, them thar “soothing” sounds are loud ones. Albeit here, everything is subjectively accounted. Although in room SPLs averaging more than 90db simply must be considered loud as an example. Practically speaking much less very likely.

I’ve gotta have a stereo that provides soft, normaland loud sound, or yields a substantial degree of variance in SPLs.

I want more than a quarter inch of spin on the volume knob to go from low to OMG!

IMHO, my home audio rig is NOT doubling as a PA system or a back up for the local sports stadiums. Yeah. I doubt they’re using enormous amounts of watts there either. Just horns.

300Bs = 2 wpc and then stop!! Wow.

What am I missing?

Looks like I need to revisit Google for the graph on watts and DBs and SPLs.

I’m not going to sleep well tonight. Maybe ever again.


wolf_garcia > rolling tubes …. …. I've noticed differences between rectifiers…234B, GZ34, and a 5Y3S…. and output tubes including KT88, KT77, KT150, 6550, and parts of an old toaster

blindjim > hahaha…. lovely. 2 slicer or 4.
Its great to have amps like that one. I always get the ones that cost so much to roll with it becomes a scary prospect to do so. One can only give so much blood each week darn it.

On distortion in recordings
A fella who told me he was a studio musician back in the 60s said ‘at times’ a more than good bit of the music was mixed for playback on automotive dashboard speakers. Plain old car speakers sitting in as monitors. Why? Because that’s where 90% of the music was going to be played.

The first thing I did in my old Chevy was to throw in a pair of Jensen 6x9s, and a Craig Power play FM & 8 track 20wpc deck. Smoking loud rig.

The more often I recall this conversation the more I think there was more to it than why much of the pop and rock and RB songs were so poorly recorded well into the early ‘90s, and beyond.

I’d guess it was lable concentric, and or artist predominate. Better lables and more popular artists recordings I’ve heard even today, sound better than those of the ‘rest of the herd” even off the same lable. Some labels don’t have as great a disparity across their artists, but the big guys do seem to get the better engineers and studios… until they buy their own houses.

Many acoustic recordings going back a long ways still sound pretty good. Electric powered instruments have had a tuff row to hoe for decades.

Thank God for mobile devices and PC desktop rigs. That’s where its more about content than fidelity. Play the bad stuff there.

Apple is still missing the boat in lieu of the onslaught of HD and lossless music and the resurgence of new or even other formats apart from Apple’s proprietary formats… and they will continue to do so until their base quits buying compressed tunes thru their IOS devices. In essence, “… its going to be a long, long time”. As Sir Elton once sang

Thankfully too, jazz and jazz vocalists always seemed to be done pretty well, then and now.

Pink Floyd sounds bad?

Unabashed blatant Heresy!

@blindjim 

The trying not exceed 20% of an amp's power was specifically mentioned by Ralph for SET tube amps due to their nature in how they distort. As I understand his point, I went back to read it carefully, one must be particularly careful with speaker matching with this type of amp by avoiding higher order harmonics.  

His statement does not include SS, Class D, OTL and other type amps.  Ralph, could you please confirm.

What am I missing?

Grannyring got it in one- well done!

Apparently that this applies specifically to SETs and not to other kinds of amps. For example, despite being zero feedback (like SETs), our amps make a fraction of the distortion at full output (about 0.5% if set up correctly) so you have a much greater *percentage of usable output power*.

I like to use that idea of ’percentage of usable output power’ as its a number that can vary widely from amp to amp. Generally speaking, tubes have greater usable output power than solid state amps seem to have but SETs are the exception.

This is all about distortion, which all amps make so the ’percentage of usable output power’ has to do with the **kinds** of distortion that are particularly objectionable to the human ear. These are the higher ordered harmonics (5th and above, particularly the 7th), IM distortion, and in the case of class D, inharmonic distortion (caused by intermodulations with the scanning frequency; similar to aliasing in digital audio).

Because the ear converts all forms of distortion into tonality (including aliasing), the distortions above all manifest as some form of brightness and hardness. By contrast the lower ordered harmonics are perceived as ’warmth’ and ’bloom’.

Its quite worthy of note that these objectionable distortions always occur in very small amounts as opposed to the lower ordered harmonics- the issue is that the ear is far less sensitive to the lower orders. In this regard I propose a ’weighting’ scheme so that trace amounts of higher ordered harmonics can be seen for what they really are- which is to say: audible!

In SETs, the first onset of higher ordered harmonics is heard as ’dynamics’ by the ear as musical energy often occurs on transients where greater power is required (in a way fundamentally different from solid state, which tends to make the the higher ordered harmonics all the time). What happens is the higher ordered harmonics (to which very importantly the ear uses to calculate sound pressure) are thus only showing up initially on the leading edges of transients and no where else, so then it is perceived as ’dynamics’. The problem is, once you are aware of this fact its easier to hear that what is really happening is the amp is making distortion. So the simple act of reading this paragraph may have ruined it for some people. To avoid this you simply need more power or more efficiency. More power in an SET means it won’t sound as good and therein lies the dilemma!

Of course all forms of distortion are to be avoided, but avoiding the the objectionable forms is far more important overall for a pleasant listening experience. This, in a nutshell, is why tubes are still around nearly 60 years after being declared ’obsolete’.

One thing that has really become evident in the last 15 years or so is that if the loudspeaker is a higher impedance that avoiding the more objectionable distortions is easier to do **regardless** of the amplifier technology. I think speaker manufacturers are slowly figuring this out as there are more 16 ohms speakers now than there were 15 years ago. Put another way, if you are tying to make a lower powered tube amp sound like music, a four ohm load is absolute anathema!

Its my opinion and also my experience that four ohms has no place in high end audio (IOW if high quality audio production is in fact the goal). The cables are more critical and all amps sound harsher and less detailed on four ohms as opposed to eight or sixteen all other things being equal. Its not only audible, you can see it in the specs of any amplifier made.

This is such a great thread and I now better understand, technical reasons,  why I have been so frustrated in the past with some wonderful SET amps. The music was wonderful at lower volumes, and they did drive my speakers to go very " loud " I was initially impressed, only to find the sound not to my overall liking longer term.

It was this whole issue of sounding "loud" when a system should not sound loud when turned up. Rather, the performance should simply swell and grow with greater impact etc....

My mistake was not the particular SET amp, but pairing the amp with a 4-8 ohm speakers with sensitivities ranging from 89-93db.  My 8-20 watt SET amps, while playing these speakers loud, always fell a little short of greatness. Greatness at low, moderate, and higher volume levels.