Ski Bum

If it's only harsh/fatiguing when you crank it, could be amp clipping. A bass boost will eat up amp headroom pretty quickly. Could also be that your amp is not clipping, but actually driving your speakers to painfully loud levels. Fortes can do that. Be careful with your hearing. REW may help get a better handle on your system's response and help with fine tuning (which includes placement, tuning via room gain, which fortes are quite sensitive to).

My present go to ss amp is a trusty ATI AT602. It provides pretty much textbook performance for a modern ss class ab amp, great specs, solid into low impedance loads, input sensitivity/gain controls (an essential feature when using high sensitivity speakers IMO), and 12v trigger. It's my "keep me honest" amp when not messing with tubes. It just amplifies, adds nothing, get's out of the way of the music.

Regarding the potential harshness, it could very well be from the loss of bass/boundary gain directly resulting from being perched up on stands. Don't be afraid to use the tone controls or eq to fix this if you haven't already. Nice work on the stands!

If anything, Chris, there seems to be a lot of overlap with the First Watt amps and the single ended tube amps. First Watt amps actually don't tout textbook perfect performance, nor are they devoid of deliberate voicing. And they don't bring much power. They appeal to the same audience as SET amps do. Some of the old First Watt threads involved lots of comparisons to tubes, and rightly so. First Watt amps seem more of an ode to engineering elegance and simplicity (along with the compromises and limitations that accompany such an approach). First Watt are aimed squarely at the curious and exploratory DIY audience. It would make sense to my crazy point of view that the tubes forum and possible ss forum were both sub-forums within the technical forum. The onus would then be on all participants to be as objective about their subjectivity as possible, giving any newbs or technically naive readers practically useful information for their audio journey. It seems that Maynard and Sloth are doing just that over in the tube forum.

Given we now have this thread regarding certain aspects of tube distortion (e.g., harmonics), I thought the entire Nelson Pass article may be of some interest to readers since the article is written in a "plain English" style and a person does not need to be an electrical engineer to understand...] Thanks for bringing this up, as I've been curious about this. I'm not quite sure I fully agree with the interpretation of the I'M distortion as merely a "complex noise floor." It's the combination of 2nd and 3rd harmonics that is responsible for the synthesized bass, which is more tonal coloration than noise. Of course, as pointed out, most of the I'M products are dissonant, so my guess is that the truth lies somewhere in the middle. Another thought, if that spray of I'M distortion is transient, only occurring during the highest peaks in the recording, what are the implications? At lower output levels, which is where we spend most of our time, where distortion may not exceed 2 percent or so, does this I'M mediated noise floor even get a chance to build up? Transient distortion is largely unrecognizable, provided the amp recovers from the clipping without further issue.

Ugh, I seem to be experiencing the buggy update reboot loop. FFS, microsoft. Should I start messing around in the registry? I'm frankly more comfortable with the deadly voltages in tube amps than getting down and dirty in the guts of a computer.

If you think about it, the two approaches are doing quite different things. In the case of a tube pre, you're adding whatever the tube circuit's harmonic output to everything, the quiet passages, the crescendos, everything. With a tube amp coupled to a speaker the process is more dynamic (clean at low output, more harmonically embellished with higher output).

Why do SETs sound so good? My wild guess: a mish-mash of various things. -harmonic coloration, being discussed in the distortion thread; given the relative power levels that Maynard pointed out, I'm not sure how much of a factor this is, but it seems reasonable, and is based on the real behavior of stuff, not tube pixie dust conjecture -output impedance mediated distortion which includes linear deviations dictated by the load, as well as the back-emf "Carver effect" which we've discussed and some of us have actually measured -the whole feedback thing (yes, directly related to the first two, and also related to the whole circuit complexity aspect). Play with global feedback on these little tube jobs and tell me it doesn't have ramifications for imaging. Too much may help the amp be linear, but the coinciding presentation also becomes, well, two dimentional/flat/boring/artificial sounding. Those are my stabs at the answer. Of course I could just be mesmerized by the shiny mercury.

Regarding ss power, too much is just enough, as you never want it to clip, ever. Technically speaking, that "decent" sound as you describe it, attained from unclipped ss power, is more accurate. But this thread is not about accuracy, it's about the glories of a little distortion. Flea watt single ended, you do get some "benefit" from their (mis)behavior, at least up to the point you don't. Gross clipping still sounds pretty gross. Klipsch sensitivity allows even single digit power to suffice, which typically has us tube guys landing in a real audio happy spot: 75-85db average levels, with just enough headroom (or faux headroom as it may be). That happens to coincide with human hearing's most sensitive range, which is advantageous for peering deep into the mix, yet never brutalizes your ears with truly high spl, hence marathon listening sans fatigue. Another point from the article, relevant to your last question, is that these benefits are realized specifically with tube amps connected to transducers. A tube pre-amp, buffer, or line stage may or may not add any harmonic coloration, it all depends on the design goals. It's pretty easy to pull of a squeaky clean tube line stage which would add nothing, or one that would embellish with some low order harmonics to add some meat to the bones. I've tried this approach, paired w/ ss amps, and just don't find it as tubetastic as the amp/speaker approach.

Note in the excerpt how the edge harmonics affect transients. The tube amp may have subjectively superior transient response as a direct result of the amp's behavior. A more well sorted amp may produce the source material more accurately, but the subjective results may be less stimulating. You're hearing it, although you may not recognize it as distortion per se. (I've had Decware amps like yours on the bench, and saw copious amounts of 2nd through 5th harmonic even at low levels.)

I think it matters in proportion to how far down the watt scale you go. I doubt I clipped my old Scott too much, it was a 20 watt amp. Drop down to a 300b at 7 watts or so, and the chance of clipping goes up, and even more when you drop into the 2a3 and even smaller sweep tubes. 45s? I think I would clip a one watt amp pretty easily. I wouldn't be at all surprised if a Khorn playing below 95db contributes less distortion than many of these single ended amps.

Derrick, some excerpts from an old but valid paper about the harmonic distortion as it relates to tube amp coloration: The second and third harmonics are the most important from the viewpoint of the electronic distortion graphs in the previous section. Musically the second is an octave above the fundamental and is almost inaudible; yet it adds body to the sound, making it fuller. The third is termed quint or musical twelfth. It produces a sound many musicians refer to as "blanketed." Instead of making the tone fuller, a strong third actually gives the sound a metallic quality that gets annoying in character as its amplitude increases. A strong second with a strong third tends to open the "covered" effect. Adding the fourth and fifth to this changes the sound to an "open horn" like character. The higher harmonics, above the seventh, give the tone "edge" or "bite." Provided the edge is balanced to the basic musical tone, it tends to reinforce the fundamental, giving the sound a sharp attack quality. Many of the edge harmonics are musically unrelated pitches such as the seventh, ninth, and eleventh. Therefore, too much edge can produce a raspy dissonant quality. Since the ear seems very sensitive to the edge harmonics, controlling their amplitude is of paramount importance. The previously mentioned study of the trumpet tone [6] shows that the edge effect is directly related to the loudness of the tone. Playing the same trumpet note loud or soft makes little difference in the amplitude of the fundamental and the lower harmonics. However, harmonics above the sixth increase and decrease in amplitude in almost direct proportion to the loudness. This edge balance is a critically important loudness signal for the human ear. RELATIONSHIP OF FACTORS AND FINDINGS The basic cause of the difference in tube and transistor sound is the weighting of harmonic distortion components in the amplifier's overload region. Transistor amplifiers exhibit a strong component of third harmonic distortion when driven into overload. This harmonic produces a "covered" sound, giving a recording a restricted quality. Alternatively a tube amplifier when overloaded generates a whole spectrum of harmonics. Particularly strong are the second, third, fourth, and fifth overtones, which give a full-bodies "brassy" quality to the sound. The further any amplifier is driven into saturation, the greater the amplitude of the higher harmonics like the seventh, eighth, ninth, etc. These add edge to the sound which the ear translates to loudness information. Overloading an operational amplifier produces such steeply rising edge harmonics that they become objectionable within a 5-dB range. Transistors extend this overload range to about 10 dB and tubes widen it to 20 dB or more. Using this basic analysis, the psychoacoustic characteristics stated in the beginning of this paper can be related to the electrical harmonic properties of each type of amplifier. Vacuum-tube amplifiers differ from transistor and operational amplifiers because they can be operated in the overload region without adding objectionable distortion. The combination of the slow rising edge and the open harmonic structure of the overload characteristics form an almost ideal sound- recording compressor. Within the 15-20 dB "safe" overload range, the electrical output of the tube amplifier increases by only 2-4 dB, acting like a limiter. However, since the edge is increasing within this range, the subjective loudness remains uncompressed to the ear. This effect causes tube-amplified signals to have a high apparent level which is not indicated on a volume indicator (VU meter). Tubes sound louder and have a better signal-to-noise ratio because of this extra subjective head room that transistor amplifiers do not have. Tubes get punch from their naturally brassy overload characteristics. Since the loud signals can be recorded at higher levels, the softer signals are also louder, so they are not lost in tape hiss and they effectively give the tube sound greater clarity. The feeling of more bass response is directly related to the strong second and third harmonic components which reinforce the "natural" bass with "synthetic" bass [5]. In the context of a limited dynamic range system like the phonograph, recordings made with vacuum-tube preamplifiers will have more apparent level and a greater signal to system noise ratio than recordings made with transistors or operational amplifiers.

It's not falling on deaf ears, J. On paper, those appear to be ideal for extra revealing, high sensitivity speakers, and it's nice to get some feedback from an actual user whose tried just about everything with speakers we can relate to. I would have one if I had two thousand bucks burning a hole in my pocket.

I would posit that for many of us, a little tube distortion is the whole point. This will invariably irritate some, using a tube amp as a processor/tone control. Que sera sera. Seriously, think of the expense involved in tube amps that perform well per prevailing engineering orthodoxy. It would inevitably be a large, pp type, employing many parts, many tubes, and with enough complexity to meet the design goals. It would be expensive, even on the DIY side, just due to parts count, not to mention the degree of expertise/time/education required as a prerequisite for all that. And you end up with something akin to, say, an Audio Research amp, that is audibly indistinguishable from any old mainstream solid state amp. That seems like a lot of effort just to end up where you started. Regarding the higher harmonics, keep in mind that as the tube amps clip the third through about the seventh harmonic play a role in the tonal coloration/compression effects that these devices exhibit. A monotonic harmonic pattern (characteristic of SE types) slips by the ear as it's perceived as added loudness and edge. Of course gross clipping that excites higher harmonics than that sounds awful.

Decware still ship in those hard sided pelican briefcase thingies? That's a nice touch to ensure they are UPS-proof.

I'm familiar with their SE84 amps, like them a lot. Two watts will only get you so far, but that may be just enough enough with Klipsch heritage. The ones I have seem to punch above their weight, but I don't listen that loud (75-85 db avg). They'll do reasonably loud, but are simply incapable of painfully loud, so your hearing is safe. They do pull off the kooky depth-of-field and presence thing characteristic of SE amps, reportedly more so than any other amps in their lineup. Erik2a3 has a Mini Torii (single ended amp of about 4 watts using 6v6 family of tubes) that his wife bought him which he has positively raved about. He's extremely knowledgeable on the tube front, so if he likes it, it's probably pretty good. If I recall correctly, the MT is one of his overall favorite amps for 'Scalas and Heresy.

Let's find out. Survey up in General forum. SSS, but so far it's 1:1.

Just curious about this as it was raised in another thread. Please vote!

It seems that relaxing the posting standards in the first place led to all this. Once folks were allowed to let their nutty freak flags fly it gave license to continue and expand their behavior, and voila, tribal factions stake out their ground, argue pointlessly, and inevitably someone gets their feelings hurt and takes a big old crap in the punchbowl to spoil the entire party. Does that about sum up the long, ridiculous story?

Why did all the forum changes go down in the first place? I think this all could have been handled by giving a few folks some enforced "time out" for their lack of self control and respect for the community, ban them if absolutely necessary, and otherwise leave things alone. Now it's just chaos of post count padding silliness.

I thought the OP was using Cornscalas or something more Klipschy. ?? Maynard, you made a post long, long ago about your whole process when designing an amp for someone, which I wanted to link to but am too lazy to go through all your posts to locate. Do you have it handy by any chance? I think it would help the OP get a proper grip on exploring the tube sound, the right way.

Change, as in audible differences, would be more pronounced with at tube output stage than a tube pre or line stage. A lot of the tube sound is due to higher output impedance and transformer coupling of tube amps. There seem to have been more than a couple good options in our own Garage Sale forum recently, from classics rebuilt by known technicians, to some single ended jobs. And per your original post, you want "cheap.' To me, that means something that presents little financial risk. edit: too late for this one, but an example: https://community.klipsch.com/index.php?/topic/157480-ampsandsound-big-ben-with-nos-tubes-800/

Your room is on the small side, your speakers are on the sensitive side. Keep in mind the relationship of power to subjective loudness, and the difference between what your Marantz can do and what an external amp can do. Unless you're quadrupling available power, the differences won't amount to a hill of beans, and that's assuming you actually need the extra power in the first place, which has not been determined. Rather than an amp, you would be better served putting that money towards a sub, and implementing bass management which will lighten the load on the Marantz.

The Quicksilver Horn amps are purposefully low gain. So is that new fancy Benchmark amp for that matter. Those eye popping, DAC like specs don't just result from fancy circuitry (although their achievements are nothing to scoff at), as simply having lower gain helps those numbers considerably. Whether you go with tubes or a state of the art amp like the Benchmark, sensible gain staging of the system is a key ingredient in the "dead quiet" recipe.

Nice expose Mike, much more thorough than my own tests. I hooked a single ended amp with output impedance ~3 ohms, no source, volume cranked, to one of my fortes. I recall reading 1.4 mv (power supply hum) when the room was silent, then blasting music through the other forte on a big ss amp to unhealthy spls and seeing 2-3 mv. At more sane levels, ones more in line with what the small amps could actually deliver, I was getting only marginally more voltage than the power supply hum, never cracking 2 mv. It's really happening, but it's buried way, way down there.