A Power Buffer:

The F4 amplifier is being released, with the first few units being distributed to special customers, and general availability in April. Like everything else from FW it is a unique amplifier.

It has no feedback and no voltage gain, only current gain. This design is sometimes called an “impedance converting amplifier”, but more commonly referred to as a buffer – in this case, a power buffer. Check out the owner’s manual posted here on the site, and for you DIYers this manual also carries the service manual with schematics and board layouts.

Somebody posted the question on www.diyaudio.com about the relative sound of the various amplifiers, and got the following answer from Jon Ver Halen at Lowther America. Since it answered the question better than I could, I reproduce it here:

“I am curious, since you are the only two who have listened to all the First Watt amps with Lowthers, as to which amp you personally like best?”

“Aha! Down to the meat of it all. There is no right answer, and it is part dependent on your taste, part on your music, and your source.”

“The F1 is super clean and dynamic. If your source is lean, your music will be lean. If your source is rich, your music will be rich. It is the real truth machine, with nothing taken out and nothing added. Ruthlessly revealing.”

“The F2 adds some 2nd harmonic to this. On lean source material this sounds better than the F1. It is putting a little color in your music, and on dry material it is a pleasant addition. Some like that additional color, some do not. Your choice.”

“The F3 sounds has a very light touch of sweetness. Sounds more like a great tube amp than any solid state amp I have heard, except that it has the same basic tonal characteristics from highs to lows - something most tube
amps dream about.”

“The F4 sounds like a cross between the F1 and the F3. Cleaner than the F2, a touch of sweetness, but the truth is still front and center. I have not heard this amp in my system (yet), so my thoughts about this may change. It is a very exciting product.”

“Nelson, with his greater experience, may be better able to describe all of these amps. But as to which is best? That is like saying vanilla is better than strawberry - it is a matter of what you enjoy. All of these bring something different to the table.”

I would only add that the current-source nature of the F1 and F2 narrows their appeal more than Jon’s comments might lead you to think. They are particularly apt if you have sensitive full range drivers in a sealed box.

Jon did get to listen to the F4’s on the Alerion loudspeakers at my place, and you can see my comments on the Alerions at www.lowther-america.com, and yes, he will get the first two off the line.

For the complete story - download the owner's manual below.

Download F4 Owner's Manual / Service Manual here: f4 om.pdf (3.5Mb)