First Watt F7 review

I still working on an F7 type amp that has two plateaus of OLG that looks something like this:

View attachment 1233895

Recently, I added a Zobel network to the O/P shown in a simplified circuit here:

View attachment 1233896

My motivation for adding this was that I have noticed that this kind of amp ( F5 / F7 ) has a tendency for some exagerated sibilance ( still there despite the fact that on my latest version there are only very small amounts of feedback 5k - 20k hz region. )

Regarding this sibilance, the zobel network was not particularly effective but it had a wonderfully positive subjective effect on midrange purity, imaging and reproduction of low level detail.

Anyone that has built an F7 / F5 type circuit might like to try adding a zobel across the amp O/P ( as close to the amp O/P as possible. ) and would be interested to hear if you notice the same subjective improvement.

If I succeed in taming the sibilance I am going to very happy with this F7 type amp.

If I do succeed I will post the final circuit here.
I see three corrections: also R7/C6 and C7/R10. I will try the Zobel. Indeed, sibilance I didn't call it (yet), but a slight over excited capability to present the high tones. I was pondering changing the feedback loop a bit with the intent the phase will change, but this is much simpler!
Would the slightest coil in the output help? Transitor outputs have that a lot. Just to force compliance into the Zobel, I could understand. With my 4/8ohm non-inductives my F5 build goes flat to above 5 MegaHerz!!!!!

. . [I don't have that in my F5. I was prepared to butcher the F5 . . .]
 
Long live the F5! How many more iterations can be squeezed out of that topology 🙂

The F5 Twighlight Zone Edition sounds very intriguing. I will take one of each. ha ha

Cambe, the F7 is supposed to have 14dB of gain. Most preamps will work with that just fine. The Iron Pre is a great preamp. Depending on how deep you want to go with it, there is the Iron Pumkin as well which is really neat. More of an investment.

Tube preamps are really nice as well but really only if your amp/speaker combo sounds to sterile and dry for you which I assume it isn't. The Iron Pre and Iron Pumking will do more to preserve the signal.