Harmonics are based on measurements, which are published.
The rest are subjective.
Maybe you are interested in someone else's subjective impression.
Then the actual harmonics don't matter.
Patrick
@gary s
I think he (NP) said predominantly "2nd order negative harmonic"
I was sitting about 12 feet from him when he described it at BA23. He specifically mentioned the distortion characteristics of the F5M. That was one of the questions that he answered.
I think he also mentioned the F5 the same way, but on that one I am not quite sure.
I think he (NP) said predominantly "2nd order negative harmonic"
I was sitting about 12 feet from him when he described it at BA23. He specifically mentioned the distortion characteristics of the F5M. That was one of the questions that he answered.
I think he also mentioned the F5 the same way, but on that one I am not quite sure.
Hey Gary,
What you're asking for is basically a full blown review of the F5m. In my 17 years expeirence following Nelson's writing (starting with the Zen articles) I've never seen anything of the kind. He's produced a tremendous amount of literature, and I believe his gift of putting "pen to paper" is often overlooked. If you pay attention there are small (usually a sentence or less) comments on what he perceives as the "sound" of an amplifier and what he personally prefers. There is quite a bit of material on the "harmonics" and it's phase for the different First Watt designs. As far as "speaker preference", once again, you can get an idea of what he prefers by following his speaker design/build threads and maybe a comment here and there. But when it come to reviews, I don't recall him ever writing a more than a one word description of a bottle of wine...I just don't think he's that fond of writing them.
I would say that there are plentyful of very useful subjective information here about the different amplifiers unique sound signature, in different applications.
But it naturally takes som time before the reports roll in. First they have to be built.
…As with the more than brand spanking new F5m. 🙂
But it naturally takes som time before the reports roll in. First they have to be built.
…As with the more than brand spanking new F5m. 🙂
I have a technical question following Gary s question about the harmonic content.
Since the only ajustements on the F5m is R8 and R9, which ajust the bias and he offset at the same time, how is the harmonic content controlled/defined without something like the trimpot between the jfets of the original F5. Is it with the matching or slight mismatching of the front end jfets? With the output devices choice?
Hubert
Since the only ajustements on the F5m is R8 and R9, which ajust the bias and he offset at the same time, how is the harmonic content controlled/defined without something like the trimpot between the jfets of the original F5. Is it with the matching or slight mismatching of the front end jfets? With the output devices choice?
Hubert
Attachments
It is significant that the F5m uses IRFP140 and 9140 Mosfets rather than the 240 versions of the original F5. It is also of note that the IRFP9140 in the F5m kit are Harris manufacture, as supplied by Pa, rather than the current production Vishay. That will be one sonic signature to try.
There are other N-type and P-type pairings that might be worth trying as well. I may have a go at those, just because. But Pa's signature is to be found in the kit.
There are other N-type and P-type pairings that might be worth trying as well. I may have a go at those, just because. But Pa's signature is to be found in the kit.
He basically sums it up on the first page in the F5m PDF 
"There are a couple performance differences between the F5 and the F5m, one being that I have
allowed some negative phase 2nd harmonic into the sonic signature which has tended to be
popular in FW amplifiers, a little more gain and variations in the output stage bias current
depending on the supply voltage and heat sink size. The larger the heat sink, the higher the
bias current and the lower the distortion."
"There are a couple performance differences between the F5 and the F5m, one being that I have
allowed some negative phase 2nd harmonic into the sonic signature which has tended to be
popular in FW amplifiers, a little more gain and variations in the output stage bias current
depending on the supply voltage and heat sink size. The larger the heat sink, the higher the
bias current and the lower the distortion."
Gary, I am fairly confident that people will get chatty about the sonics once they are comparing the F5 against the F5m. Lets face it, there will be a few addicts here that will have both the F5 and the F5m. Kevin is right in that Pass does not generally review his work. I think tossing something out into the world and gathering other people's uninfluenced sonic impressions is a part of his research.
I am very tempted to make one of these myself. If the JFETs have different IDSS like how Ylab and Zen Mod suspect, just the JFETs and the Harris parts themselves are well worth the purchase...
I have a cutting board, 400va 18vac transformer (and a plitron 20vac 600va transformer 🤔) bridges, a couple of populated cap boards, and a couple of damaged 5U heatsinks all begging for some heat...
I am very tempted to make one of these myself. If the JFETs have different IDSS like how Ylab and Zen Mod suspect, just the JFETs and the Harris parts themselves are well worth the purchase...
I have a cutting board, 400va 18vac transformer (and a plitron 20vac 600va transformer 🤔) bridges, a couple of populated cap boards, and a couple of damaged 5U heatsinks all begging for some heat...
The 5m sounds better. The pace is more relaxed. It's more forgiving as-well. I think the og F5 has maybe a little more bass control.