Sylph Audio FB100 Stereo Amplifier Kit Review

[DMill]

It measures amazing. Is it just another landfill product though? Should that be a consideration?

 

[RandomEar]

If the capacitors have greatly different impedance curves, is it implied that one might be closer to the theoretical ideal than the other?

I guess so, but I'm not familiar with crossover design. Some types definitely offer "sharper" curves with steeper gradients around the self resonant freq.

Can you provide some examples of these different impedance curves? It would be interesting to see them, especially if they include distortion response curves.

I think only a speaker manufacturer will have measured distortion curves with the required resolution. I can only link to common examples for capacitor impedance curves:

[Source]

This article by Murata also gives some more examples, although the graphs are a bit uglier.

Whatever was actually tested by KEF, they noted that in their whitepaper that "the component values and filter responses are identical". The graph in question showed the difference in THD between the measurements for the devices that were being compared. The THD levels for both devices were quite low, so it would seem that the "components" were generally behaving quite linearly in both. However, there was a measurable difference in THD, which can probably be assumed to have been repeatable. It would seem that was all that KEF were attempting to highlight, without presenting full details as might be expected of a NACA engineering report.

I don't doubt that different types of capacitors or those with different basic specs will perform different in a crossover. The KEF paper is very low on actual data, though. My main point is that a "high end audiophile capacitor" won't perform better than a "standard industrial cap (same type, same specs)". If manufacturers start arguing that their amp or whatever else now sounds better because they switched from electrolytic cap A to electrolytic cap B and the only difference between them is the color of the case and maybe the rated service life, that's just bullsh*t marketing.

 

[amirm]

It measures amazing. Is it just another landfill product though? Should that be a consideration?

Why? The IC used in these amps is made for high volume consumer use (soundbars, smart speakers, etc.). Its protection circuit is extremely robust. I suspect its reliability is far better than any typical class AB amp. The failure mode likely will be the power supply you pair it with. I would go with their recommendation of a name brand company like Meanwell.

 

[amirm]

Primarily, long term reliability?

Why would what they write on their website impact how reliable it is? And at this sort of cost, what is your liability anyway? I have two, let me repeat, 2 Mark Levinson amps at $25,000 each which have gone faulty. Harman doesn't support them because they are discontinued. I am supposed to ship them to some outfit in Dallas to service at heaven knows what cost. They weigh 120 pounds each so you can imagine just the shipping cost to get them there and back. Likely I will fix them myself one day but with zero information available on them online, and a ton of surface mount parts, it is not going to be easy.

When you buy a power amplifier, it failing is just part of owning one. It is just a matter of probability.

 

[Power Pop 23]

Why would what they write on their website impact how reliable it is? And at this sort of cost, what is your liability anyway? I have two, let me repeat, 2 Mark Levinson amps at $25,000 each which have gone faulty. Harman doesn't support them because they are discontinued. I am supposed to ship them to some outfit in Dallas to service at heaven knows what cost. They weigh 120 pounds each so you can imagine just the shipping cost to get them there and back. Likely I will fix them myself one day but with zero information available on them online, and a ton of surface mount parts, it is not going to be easy.

When you buy a power amplifier, it failing is just part of owning one. It is just a matter of probability.

Ouch, ouch, ouch


Perhaps create a thread entitled Heavy Gear Seeks Round Trip Ride Between Seattle and Dallas

I can imagine a sub-forum of similar threads looking for a ride to the last remaining service center.


Or, consider creating a thread chronicling your journey to restore them to health.

May it take you less time than it took for Odysseus to get home.


Lastly, after measuring the rebuilds for ASR, consider your heirs and selling them....


Blessed be amplifiers that are powerful, lightweight and affordable.

 

[PristineSound]

Why would what they write on their website impact how reliable it is? And at this sort of cost, what is your liability anyway? I have two, let me repeat, 2 Mark Levinson amps at $25,000 each which have gone faulty. Harman doesn't support them because they are discontinued. I am supposed to ship them to some outfit in Dallas to service at heaven knows what cost. They weigh 120 pounds each so you can imagine just the shipping cost to get them there and back. Likely I will fix them myself one day but with zero information available on them online, and a ton of surface mount parts, it is not going to be easy.

When you buy a power amplifier, it failing is just part of owning one. It is just a matter of probability.

Coming from the Benchmark AHB2 teardown thread, I probably repeated the words "pre-sales and post-sales support" like 5 times. I feel like for expensive equipment, it is super important that the manufacturer has a history of servicing their products for a prolong period of time. Some of the well-known manufacturers who does that are Bryston, McIntosh and as far as I am aware Benchmark.

It is super disappointing the Harman sold a $25k amp that (a) cannot last decades (b) no long-term service and repair available.

For cheap and disposable amps like this Sylph Audio, sure, who cares aside from filling up the landfills but $25k for one channel, that hurts.

 

[Chrispy]

Coming from the Benchmark AHB2 teardown thread, I probably repeated the words "pre-sales and post-sales support" like 5 times. I feel like for expensive equipment, it is super important that the manufacturer has a history of servicing their products for a prolong period of time. Some of the well-known manufacturers who does that are Bryston, McIntosh and as far as I am aware Benchmark.

It is super disappointing the Harman sold a $25k amp that (a) cannot last decades (b) no long-term service and repair available.

For cheap and disposable amps like this Sylph Audio, sure, who cares aside from filling up the landfills but $25k for one channel, that hurts.

Sometimes just that following a "brand" alone isn't enough without support. Levinson has never been well known for longevity/support from what I can tell. Just a lot of marketing.

 

[witwald]

I can only link to common examples for capacitor impedance curves: ... [Source] ... This article by Murata also gives some more examples, although the graphs are a bit uglier.

Thanks for providing those examples. I hadn't seen such impedance curves before, and those for the larger capacitors were quite instructive.

I don't doubt that different types of capacitors or those with different basic specs will perform different in a crossover.

From the examples that you provided, I'd be hoping that the capacitors chosen for a passive crossover were going to behave closely like "ideal" capacitors in the audio frequency range, and probably out to an octave or two beyond that. Having siad that, even a non-ideal capacitor impedance curve would likely produce quite usable crossover filter responses in the typical crossover operating range in the 20 Hz to 20 kHz audio spectrum.

My main point is that a "high end audiophile capacitor" won't perform better than a "standard industrial cap (same type, same specs)".

That is a valid point, all other things being equal. However, although it omitted some specifics, the KEF whitepaper did provide information that some crossover circuit components can cause THD distortion to occur in the output of a crossover filter. Of course, the distortion levels peaked at about 0.32%, so that is hardly an overwhelming amount of distortion. Nonetheless, observing that this can occur then allows the designer(s) of loudspeaker systems to mitigate against the occurrence of this distortion by a suitable choice of passive components. I think that that was what KEF were trying to get across, nothing more and nothing less.

 

[DMill]

It is super disappointing the Harman sold a $25k amp that (a) cannot last decades (b) no long-term service and repair available.

I was also shocked to hear Amir’s comment to me that his Levinson amps did not have some sort of support for repairs. That is really disappointing. My comments around this amp were that it feels like a landfill product. I have no doubt Amir’s measurements and appraisal of this amp are correct. And TY btw. Only to say if something does go wrong, and it happens in all electronics, it’s a brick. I’m not even sure it’s worth the cost to repair even if you could find parts for it, which is unlikely. Overall, my only problem with some low cost performant devices like this one is this mentality of it being completely disposable. And maybe we think about that on this site when evaluating them? Amir’s experience with Levinson is not enough for me to dismiss a number of brands that are building and supporting their customers for many many years.

 

[PristineSound]

I was also shocked to hear Amir’s comment to me that his Levinson amps did not have some sort of support for repairs. That is really disappointing. My comments around this amp were that it feels like a landfill product. I have no doubt Amir’s measurements and appraisal of this amp are correct. And TY btw. Only to say if something does go wrong, and it happens in all electronics, it’s a brick. I’m not even sure it’s worth the cost to repair even if you could find parts for it, which is unlikely. Overall, my only problem with some low cost performant devices like this one is this mentality of it being completely disposable. And maybe we think about that on this site when evaluating them? Amir’s experience with Levinson is not enough for me to dismiss a number of brands that are building and supporting their customers for many many years.

I couldn't agree more about buying cheap amps like this. It's he disposable mentality that bothers me. But I do think there is a use case for this because of the price range. Even if it becomes a paperweight at least it's $175 paper weight, better than a 100 lbs, $25k kettlebell. Harman ought to be ashamed of itself.

 

[broe]

I have a single ended tube preamp which I really like.
As a tube preamp it depends on a highish input impedance of the power amplifier.

In all the reviews of power amplifiers at audiosciencereview and the specs sheets this important parameter is missing.
Can someone help? Amir?

(No, please no comments that I should buy another preamp)

 

[pma]

In all the reviews of power amplifiers at audiosciencereview and the specs sheets this important parameter is missing.

Input impedance measurement and output impedance measurement should have been a basic part of the amplifier test protocol. Sylph Audio is NOT declaring input impedance at their official page:

[FB100 Stereo] Class-D Amplifier Kit – sylphaudio.com

sylphaudio.com

This is, to me, a mistake. Yu can try to contact @SylphAudio member directly here at ASR.

 

[jareinertson]

Why would what they write on their website impact how reliable it is? And at this sort of cost, what is your liability anyway? I have two, let me repeat, 2 Mark Levinson amps at $25,000 each which have gone faulty. Harman doesn't support them because they are discontinued. I am supposed to ship them to some outfit in Dallas to service at heaven knows what cost. They weigh 120 pounds each so you can imagine just the shipping cost to get them there and back. Likely I will fix them myself one day but with zero information available on them online, and a ton of surface mount parts, it is not going to be easy.

When you buy a power amplifier, it failing is just part of owning one. It is just a matter of probability.

@amirm Best of luck with your ML repairs. ML29 here still chugging along after cap refresh in 2025. Good Levinson service support here in The Netherlands from the distributor, however it’s a bit further than Dallas…

 

[SylphAudio]

I have a single ended tube preamp which I really like.
As a tube preamp it depends on a highish input impedance of the power amplifier.

In all the reviews of power amplifiers at audiosciencereview and the specs sheets this important parameter is missing.
Can someone help? Amir?

(No, please no comments that I should buy another preamp)

The FB100’s non-inverting op-amp provides a naturally high input impedance, but the actual differential impedance is set to 20kΩ by a resistor to ground. If you need a different impedance for your setup, we can easily swap that resistor out for you.

The FB100 requires a differential (balanced) input. Because of this, it might not be directly compatible with your setup without using an unbalanced-to-balanced converter.

 

[broe]

The FB100’s non-inverting op-amp provides a naturally high input impedance, but the actual differential impedance is set to 20kΩ by a resistor to ground. If you need a different impedance for your setup, we can easily swap that resistor out for you.

The FB100 requires a differential (balanced) input. Because of this, it might not be directly compatible with your setup without using an unbalanced-to-balanced converter.

Many thanks for the fast and comprehensive Answer. I am sorry not to be able to use your amplifier!