Member's recommendations for tube amplification

Jack Elliano developed a technique to reduce distortion he called 'Class A3' (as opposed to class A or class A2). As a result, his SET amps were the exception to the 20-25% rule to which most SETs adhere. Jack had a patent filed on the concept.

Regarding discourse on the threads, I find for the most part that the best approach is to not take things personally regardless of the conversation. I see it as not really being my problem when someone makes personal attacks. Occasionally I'll get trolled; however the site is moderated, but in order to invoke the moderation you have to report the offending post. I find that its really important to not respond to a post that offends you. Occasionally the thread gets taken over by trolls and at that point I stop posting on such a thread- there is no further point.

These tactics work pretty well regardless of what site I post. There is one site, hydrogenaud.io, that is very much all about objective measurement and also has an unusually high troll content; on that site you have to have a pretty thick skin. But the same ideas apply even there.

When you take all the weirdness and such that are part of the internet forum experience personally, that's when it stops being fun. And the fact of the matter is that there isn't a good reason to take anything said here personally! 

I am sort of in agreement with clio09 about the possibility that someone may be satisfied with the result; it all depends on the specifics, such as how easy a load the speaker is, type of music, how loud one listens, how large is the room, and most importantly, what compromises one is willing to make.

Just to be clear I do like to play things louder and always have. I used to play bass in several orchestras and orchestras play loud a lot. If I put on Wagner's Das Riengold (Solti Decca LP) I want the event to come off as if its happening. Its not just head banging (although I do that too).

@grannyring I'll contact clio09 and let him know you meant no harm.

^^ a 1KHz tone really isn't anything like an actual musical signal, which is a bit harder to reproduce, but the sound pressure meter isn't going to care about that.

The speaker is measured in sensitivity, not efficiency, so to correct for that your actual efficiency is more like 94 db. I'm sure your use of the subwoofer is helping a lot!

I often listen at higher levels (95-100db), but the trick is that at those levels the system does not sound loud. My speakers are 98db 1 watt/1 meter and they are 16 ohms at the same time Classic Audio Loudspeakers model T-3). Plus I am usually using amps with 60 watts output and at that power the distortion is quite a bit lower (about 0.5% THD at full power despite no feedback). So the result is less loudness cues generated by the system, which allows for higher volume levels without it sounding loud. Instead it sounds relaxed and effortless.

^^ a 1KHz tone really isn't anything like an actual musical signal, which is a bit harder to reproduce, but the sound pressure meter isn't going to care about that.

The speaker is measured in sensitivity, not efficiency, so to correct for that your actual efficiency is more like 94 db. I'm sure your use of the subwoofer is helping a lot!

I often listen at higher levels (95-100db), but the trick is that at those levels the system does not sound loud. My speakers are 98db 1 watt/1 meter and they are 16 ohms at the same time Classic Audio Loudspeakers model T-3). Plus I am usually using amps with 60 watts output and at that power the distortion is quite a bit lower (about 0.5% THD at full power despite no feedback). So the result is less loudness cues generated by the system, which allows for higher volume levels without it sounding loud. Instead it sounds relaxed and effortless.

For what it's worth, I filter out 70Hz (-3db) and below (-12db @35hz) from the amps and speakers (using a pair of passive filters) and I am letting my ML Depth i subwoofer handle the bottom range; IMO, this has worked wonders in driving the Omega speakers with the Franks with substantially less distortion; I don't detect any distortion, but if there is, I have no objections to it :)

The point is that unless the amp is outright clipping, the ear does not detect the distortion as such- in almost all cases, the ear converts distortion into tonality. But because the ear also uses higher ordered harmonics as a loudness cue, if there are higher ordered harmonics in the signal, the ear will hear that as louder.

In an SET, the higher orders start to show up when the amp gets to about 20-25% of full power. Since music has most of the power in the transient leading edges, if the distortion is only showing up there it will come off as 'dynamic'. Lots of people like that (often though without understanding how its happening) but it certainly isn't natural!

If you really want to hear what an SET does right you need a speaker that is efficient enough that the 20-25% of full power is not exceeded.

The thing about the Coincident amps is that they just don't make enough power. The speaker has an efficiency (we hope; if its a 4 ohm load the situation gets worse) of 94 db. 7-10 watts is simply not enough power, especially if you consider that with an SET, the ideal speaker for a given amp will be so efficient that there is never a demand for more than about 20% of full power.

If you break this rule, the SET will sound a lot more 'dynamic' than it has any business being, due to distortion generated that the ear uses as loudness cues. The thing is, once you know that is the case, its hard to listen to a setup like that and not be aware of the distortion. So reading this may have wrecked it for you.

In short, while the *idea* is attractive, in practice an SET won't work very well with this speaker although it may sound fine at low volumes.

Most SETs employ DHT (Directly Heated Triodes) like the 300b, 845 and 2A3.

DHTs can be used in push-pull as well.

If you want more than about 10 watts, IMO/IME you are far better off with a push-pull amplifier, and in your case with your speakers you will be needing more than that unless you are listening from only a few feet in a small room. If in an average room 60 watts will be a good power rating if your speakers are 94db.

The impedance of the speaker makes a difference too; generally speaking you will get better performance out of any tube amp if the impedance of the speaker is 8 ohms or higher as opposed to 4 ohms.

Balanced operation can be very helpful! If you have monoblocks this will allow you to run shorter speaker cables which will win you greater impact and definition. You can run longer lengths of interconnect cables if they are balanced, and if the preamp supports the balanced line standard (be forewarned- most high end audio preamps do not) the length of the cable and how expensive it is will have little impact on how it sounds. BTW there are balanced line tube preamps that support the balanced standard- we make one example (which also happens to be the descendant of the first balanced line preamp made).

Good Luck with the Quest.