1st impressions Solo ULD trial

gbr2004uk wrote: By the way, I've been reading up more stuff around the web, this business of tube amps producing even harmonics, and solid states producing odd harmonics, the former sounding better to most people, the latter, the reverse.

Marcus Graham Scroggie, B.Sc., F.I.E.E., (1901–1989) was a British technical author active in the fields of radio and electronics.

I wish I could call on him to explain to you and many many others what utter bullsh*t you've been reading.

Probably written by a non-technical marketing man and regurgitated like vomit all over the web.

Spot on. As I turned the page I saw Graham has put it much better than I could have.

Now, we can look at the above harmonic distortion in another way. We can imagine a straight diagonal line which represents linearity ( y = x ) but one end - the spring end - causes the line to curve. Because we only have one curve it must be of the form y = x², and that is a quadratic function and so is second order.

If we make it push pull then we will have curves at both ends. This makes it a polynomial of the form y = x³, and that is third order.

But if we unbalance the push pull we have both second and third orders and possibly 4th order, and we could if we wanted, emphasize the second and 4th orders.

One such circuit is the quasi-complimentary output stage used in several early transistor amplifiers due to the lack of good PNP power transistors of that time.

Now, it can also be argued that the VAS (voltage amplifier stage) contributes to the third order, and that will be true where class A-A techniques are used because class A-A is a form of push pull.

And, unless you have a very low powered SET (single ended tube) driving an output transformer (try making it high power...), then you will need two valves working in push pull, and therefore there will be a curve at each end of the line, which makes it third order.

But then it could be argued that the VAS uses single ended valves which have only one curve making second order harmonics, and so you have a combination of second and third with a valve amp.

And also, the early transistor amplifiers by the above argument have a combination of second and third.

It is only when we bring on the fully complimentary transistor amplifier, supposedly done that way to cancel distortion, that we can't have any (or enough to warrant it) second order harmonics, because we have double ended curves everywhere.

But what if the distortion from a transistor amplifier was so low it could not be heard?

The valve amplifier would then obviously differ because it is producing distortion.

But if that distortion was also low enough as not to be detected by ear, what then could be the difference?

I have been telling you that answer for a number of years.

This is one of many occasions where I know Graham knows a lot more than me and that's why my music sounds great through his gear. I'd say let your ears decide and then step put of this thread.