WolfX700 Measurement of DIY Firstwatt F6 Clone

[WolfX-700]

In the AHB2 thread, I said I've been obsessed with making different types of power amplifiers for myself. In this thread I will measure one of the units.

If I didn't get it wrong, Nelson Pass's FirstWatt collection is a public release design and encourages DIY. I think DIY Power Amp based on the design released by this series for myself use will not involve infringement of intellectual property rights.

This is the finished product of DIY:

It is based on the design of FirstWatt F6, and I made some efforts in the selection of components during the production process.

I knew before production that this was not a high-performance unit. From the few Firstwatts I chose to make, I'm just curious about the characteristics of some special circuit architectures.

Let's take a look at it now:

Recently I have also been thinking about some measurement issues. The following Multitone is a result of my thinking: Take a multi-tone measurement with pink noise attenuation and read TD + N. I personally think that the characteristics of music sounds are closer to the distribution of pink noise, and polyphony is closer to the actual situation of music sounds.

Summary: The result of DIY should be to or even exceed the Spec on the Owner's Manual. From a DIY perspective, it should be successful.

 

[pma]

It is a shame what NP is throwing to the builders.

 

[restorer-john]

It is a shame what NP is throwing to the builders.

Serves to make his commercial offerings look better I guess.

 

[Tks]

RIP

 

[JIW]

Recently I have also been thinking about some measurement issues. The following Multitone is a result of my thinking: Take a multi-tone measurement with pink noise attenuation and read TD + N. I personally think that the characteristics of music sounds are closer to the distribution of pink noise, and polyphony is closer to the actual situation of music sounds.

Have a look at the signal with EIA-426B spectrum and 12 dB crest factor used by Dr. Anselm Goertz for Sound & Recording and Fidelity Online.

Test signal is a multi-sine wave with 60 excitation frequencies and a weighting according to EIA-426B was used for an average music signal. The signal has a crest factor of 12 dB. The graph in Figure 15 shows, the spectrum of the excitation signal (green curve), the measured spectrum of the radiated from the speaker signal (red), and the extracted distortion components thereof (blue).

Source: https://www.fidelity-online.de/2015/12/16/neumann-kh-420-messungen/

 

[Ilkless]

Have a look at the signal with EIA-426B spectrum and 12 dB crest factor used by Dr. Anselm Goertz for Sound & Recording and Fidelity Online.

Source: https://www.fidelity-online.de/2015/12/16/neumann-kh-420-messungen/

I finally understand what that graph means.

 

[SoaDMTGguy]

I have a question about the distortion graphs at the top. The peaks at 30 and 50 I assume to be power supply noise. What about the noise from 100 Hz to 1000 Hz? Is that caused by the audio circuit? (I should probably rereview Amir's articles)

If you moved the power supply into a separate chassis connected with an umbilical, would that eliminate the power supply noise?

I appreciate you taking detailed measurements of this unit!

 

[Gsrchrisu1]

So I am guessing it measures like crap. But how does it sound? What do you suggest that sounds better for the 800 dollar approx build price. Built a f6 and a m2, both of which massacre my Class D icepower builds, which is to be expected. But I would wager the Icepower measures alot better.

 

[SoaDMTGguy]

So I am guessing it measures like crap. But how does it sound?

Don't you know the first rule of Audiophile club? Subjectivists never ask how it measures, and Objectivists never ask how it sounds

 

[Walter]

Nelson Pass' amps generally don't measure well, but the ones I've heard sound great when used with the type of equipment they were designed to complement. A couple of decades ago, over a couple of weekends I got a chance to hear a few different high end speakers being powered by amps from Pass Labs, Mark Levinson, and Jeff Rowland in the same well-treated dealer demo room. Obviously, there was no immediate switching and acoustic memory is unreliable, although it was semi-blind in that I was sometimes kept unaware of what was connected until I had voiced my opinion. The best in my opinion was ML monoblocks paired with Revel Salons (not V2), with the ML and Revel Studios 2nd. However, with every single other speaker, I thought the Pass amp sounded best--which really frustrated the dealer since that was the only one of the three he didn't sell new (it was a trade-in). I was not impressed with Rowland amps at all, except to look at. I thought even a much less expensive Classe sounded better. (In the end I decided I was crazy to consider spending that much and bought a very nice system which in its entirety cost less than any of those three amps.)

 

[SoaDMTGguy]

The sound of a system, and of it's electronics, is such a subtle thing. It's easy to brush it off and say "All amps sound the same", because mostly, they do. But then, they also don't. I think you can "lean in" to hearing amp tone, as subjectivists do, but I also think objectivists can "lean out" and *not* hear the difference, and I think both can be right.

My BA-3 has a fun little knob which adjusts the balance of the push-pull stages, changing the ratio of the 2nd and 3rd harmonics, and the overall amount of distortion. It is absolutely audible, and what is "correct" is debatable. It's a fun feature that I'm still adjusting and experimenting with.