Bland_username42069
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The gain setting that doesn’t cause clipping
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Fosi Audio Box X5 Phono Preamp Review
- Thread starter amirm
- Start date
In this case, the same things that bug @krabapple, bug me, too (and likely, many others).
For those that like those things, I have a few suggestions:
Tariffs: no need to mention them at all (but have this suggestion): Don't like the price, don't buy it.
'horrendous': more or less same advice: Don't like it, don't buy it (no need to tell us why [unless you bought something else because of a certain reason, then 'what & why']).
Swapping out internal components: that is nice that you can: but I try to buy things that do not make me feel a need to do that.
And 'circuit design & unit measurement (sort of rolled in to internal component swap out, also):
If I bought it, it's likely that I did that because I do not want to go through the hassle of redesigning circuits & remeasuring things until I manage to beat the original design.
Feeling a need to do that: would indicate that I made a bad buying decision.
Perhaps there should be a "why I don't like 'this particular unit' and what I feel they should have done thread on each unit.
That way, those of us interested in the unit can read it separately, if we wish to do so.
And the device's main thread would be less cluttered.
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Usually, a manufacturers suggested retail price at the beginning of a review would nice (so we know if we should be even looking at it or not within our budget concerns).
Because: if it is not remotely within our budget, we can be pretty sure that we are not going to buy it. Although reading about it could still be quite interesting.
Pretty much all
Amir provides the measurements, but then some folks don't understand, while still thinking of themselves as 'scientific'. The latter term is just another badge they attach to their stereo as an approval. Thing is, there's a problem with subjective preference. Too much 'critical listening' happens as if it were about approval rather than fun. Stereo, mission impossible.**
I personally think that the SINAD ranking isn't fair in this case. The standard for measuring phono pres isn't well set. Further on, I would say that a 'good enough' should be determined and publicated. See may post #862 for some reasoning.
** Example: load capacitance and resistance; adjust to your liking via equalizer (passive with R/C filter elsewhere is possible)--but there is no liking it seems. External approval needed. And many more of those uncertainties. External approval needed.
I'm OK with arguing for other parameters being measured, if you've got the evidence that they routinely matter (i.e., are audible in typical applications)
But perhaps more interesting/illuminating to ASR consumers would be some discussion of how, and under what circumstances, this Fosi might differ in use (which means either audibly, or in terms of useful features being present/absent), from, say, the two Cambridge phono pres that flank it on the SINAD graph. Simply: why might one want to choose one over the other, aside from price and look?
Just by way of example -- I just checked out the thread for Amir's review of the Cambridge Solo -- another annoying thread full of diversions. The Solo's graphed RIAA tracking (FR) seems obviously inferior to the Fox X5's. (How audibly so, I won't venture to say.) Yet the Solo is ranked higher. Is this due to something audible/feature-wise that is superior?
But perhaps more interesting/illuminating to ASR consumers would be some discussion of how, and under what circumstances, this Fosi might differ in use (which means either audibly, or in terms of useful features being present/absent), from, say, the two Cambridge phono pres that flank it on the SINAD graph. Simply: why might one want to choose one over the other, aside from price and look?
Just by way of example -- I just checked out the thread for Amir's review of the Cambridge Solo -- another annoying thread full of diversions. The Solo's graphed RIAA tracking (FR) seems obviously inferior to the Fox X5's. (How audibly so, I won't venture to say.) Yet the Solo is ranked higher. Is this due to something audible/feature-wise that is superior?
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The information is there. As a supplement, I mentioned elsewhere more generalized results from a script that discusses various applications of the FOSI X5 as an example. I do not want to publish the script because it is subject to a third party’s copyright whom I have not yet been able to reach. You surely don’t expect Amir to get involved in purchase advice. From people with a scientific mindset, I expect a certain amount of independent effort. The latter is missing, though, on a regular basis.
With deviations as low as half a dB, that's clearly irrelevant.
Could it be cherry picked?
I decided for the FOSI X5 after some lighthanded reasoning. The only thing I took away from this thread was the reminder on the opamp.
I think you missed my point.
Which is why I purposely wrote inferior, which they objectively are, while leaving audibility aside.
SINAD difference is extremely measurement-focused but itself is not always 'relevant'. Yet I remain curious about the ranking process here.
You think so--the current noise might be another parameter not yet covered. On audibility in general, I have my own stance. Especially when it comes to phono, people just taste distortions that are much more than a grain of salt. Subjectivity, facing that much of signal shaping, is in order. But not only there is severe, unavoidable degradation of what might be intended to be in the grooves. The physical process of the analg media dictates what goes in there to begin with: not for the better. We all (should) acknowledge that.
So, I miss your point, because there is no objective data that would help out. When customers say, their phono pre XYZ sound so transparent, well, I lough out in silence. It's in their imagination - transparently exposing all the nasty limitations, the wear and tear maybe? 3% harmonics from the record/needle, but only if it is 'sharp, versus 0,001% versus 0,01%, really? But so be it. It actually helps with believing in the replay, right?
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Roland68
Major Contributor
You seem to be misunderstanding something here. There's no device ranking at ASR. You won't find the kind of device ranking you see in some test magazines.
There are SINAD lists where the devices are ordered according to this metric, providing an overview. However, this has nothing to do with an absolute device ranking.Auch wenn SINAD eine der wichtigsten Messgrößen ist, stellt es nur einen Faktor unter vielen dar, der bei der Geräteauswahl relevant ist.
You are solely responsible for evaluating the review and the measurements for yourself, as well as any other information, recommendations, comments, and so on. This will result in your own personal ranking list.
You also criticize the thread for going off-topic in certain areas that don't interest you. That's also a very one-sided view that only concerns you personally. If many other users weren't interested, these posts wouldn't exist.
Many users have a technical background and are also interested in the structure of the system. For me, the device's construction and the components used are definitely key factors in my purchasing decision. I would never buy a device without having seen the inside first.
Discussing such things also belongs in a review thread, as it complements and completes a review.
Funny enough a was deciding between exactly the two Cambridges and this Fosi X5 . I decided Cambridge because the Fosi lacks any rumble filter .
I also a bit indecisive on what cart to use , so I opted for the DUO as it has MM and MC , but after that i discovered that even if both the SOLO and the DUO has constanly engaged rumble filters ( as it should be ) .
The SOLO actually has a better rumble filter 15Hz 12dB octave and 12Hz 6dB octave for the DUO ?? What the hell Cambridge ??
A clear use of limited knowledge from my side
But it works very fine for me and is very quiet indeed and is probably good enough by a wide margin for most people including me . As i have very limited knowledge on RIAA and nothing to compare against , I can only note that it is a low noise amplifier
My original interest was for a classic audio product , but shop was closed at that moment in time for an undisclosed length ( it's since opened for orders )
I also a bit indecisive on what cart to use , so I opted for the DUO as it has MM and MC , but after that i discovered that even if both the SOLO and the DUO has constanly engaged rumble filters ( as it should be ) .
The SOLO actually has a better rumble filter 15Hz 12dB octave and 12Hz 6dB octave for the DUO ?? What the hell Cambridge ??
A clear use of limited knowledge from my side
But it works very fine for me and is very quiet indeed and is probably good enough by a wide margin for most people including me . As i have very limited knowledge on RIAA and nothing to compare against , I can only note that it is a low noise amplifier
My original interest was for a classic audio product , but shop was closed at that moment in time for an undisclosed length ( it's since opened for orders )
As a diy'er one could substitute the X5's 47µF decoupling capacitors (C2, 8, 9 see below) with 1,5µF each to form a shallow, yet steep 18dB/oct filter with -3dB at 20Hz. From my experimentation the major contribution is found around 14Hz, where the filter would attenuate rumble by 6dB. 10Hz is down by 10dB.
I didn't try so far, but might do once I reorganize my stock of Cs. I might because using a Denon DP37-F w/ a servo tonearm, or a Thorens 126 Mk III w/ a well damped AT3600 respectively I find no prob/ after the digital equalizer. But, there ain't no deep bass on vinyl anyway (because of the media's *practical* limitations), so I might go for it.
Link to schematics (no warranties, second source): https://www.diyaudio.com/community/attachments/fosi-phono-box-x5-audio-schematc-jpg.1486700/
To quote myself
SINAD difference is extremely measurement-focused but itself is not always 'relevant'. Yet I remain curious about the ranking process here.
Do you literally not understand what I meant there? SINAD is presented on ASR (and specifically in the Fosi X5 review that Amir wrote) as a rank-ordered bar graph.
So to be even more explicit, I was wondering which component of the formula for generating the SINAD number led the Cambridge Solo to have a 'better' (slightly higher) SINAD number than the Fosi X5.
We all get to have preferences. Now we've both stated ours, and doubtless both are shared by other ASR readers.
"Component of the formula"? It's just two components, THD and noise. Generally, they are not measured separately. And THD is (largely) irrelevant for phono stages. And, as has been known for years, phono stage measurements of a MM stage without a cartridge connected are also basically irrelevant. This is particularly true when you're measuring bargain bin products and cannot trust that the designer did not use a completely inappropriate opamp. In the words of someone else here who has measured this sort of thing extensively, the selection of the input opamp used in this device was "incompetent." In real life, it will never perform as measured. That it is anywhere close to the top of the "rankings" is either due to this incompetence (at best), or purposeful deception.
In the end, there are not enough measurements (generally) to fully characterize the phono products measured, plus they are not performed in a way that matches real life, so the measurements just aren't that useful except for sorting out the real junk that has obvious problems other than SINAD. You're never going to use the measurements conducted here to actually tease out a top performing unit, because 1) they are not nearly thorough enough, and 2) are not conducted under real-world usage conditions. I am not the only one who wishes those charts would go away, because they look an awful lot like "rankings" and probably result in uninformed or underinformed people buying things that don't deserve to be near the top of any "ranking". And who can blame them? The impression given is that it's a good product, when it's merely adequate, at best.
That said, the Cambridge uses an NE5532 input op-amp. I had to waste a bunch of time on a YouTube video to figure that one out, so you're welcome. That's a proper choice, probably did not allow it to "cheat" like this Fosi on the SINAD measurements, and in real life and actual use connected to a real phono cartridge there is every reason to believe it would outperform the Fosi by a good margin. That it was designed by competent British engineers with (presumably) lots of experience with phono stages also suggests it will be better. At the current $200, which to buy is a no-brainer, if you're obsessed with having "top of chart" performance. Or just get a Schiit Mani 2. The Schiit is a far safer choice that costs a few bucks more.
Personally, I would never pay money for this Fosi since it has no rumble filter. That also goes for any other phono stage. Why pay money for something that is probably no better than and offers no more features than (excepting MC compatibility) what Denon/Marantz has put in all of their receivers basically for free for years? I guess if you don't have a receiver to connect it to... Still, I often wonder how many people buy something like this thinking they're getting an improvement when, well, they're not. Denon/Marantz just keeps using that same phono stage with its active RIAA over and over. And it's pretty good. So is the Fosi, but for $35 more you can get something that actually has useful features. There's just no good reason to buy this thing when a Mani 2 exists. Heck, I don't care. Even take a flyer on an $80 Aiyima T3 Pro. It can't be much worse.
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You can do this with C2 and C8. The cutoff frequency of the highpass created by C9 however depends not only on R15 but on the load impedance as well. If this is the typical 10k you need to double C9s value (combined load is 5k then), if it's lower C9 must be even bigger. If you don't know the load impedance better leave C9 as it is.
It's a wiki - means it's community driven, and relies on data and especially the correction thereof by people like YOU, who have better data.
lini
Active Member
It's a wiki - means it's community driven, and relies on data and especially the correction thereof by people like YOU, who have better data.
Well, right you are. So I've just posted a request for correction on the corresponding discussion page.
Greetings from Munich!
Manfred / lini
Hooray! The world just improved by a little bit
lini
Active Member
*lol*
Not my first one, btw - as you can see on the discussion page for the Denon DL-301II.
Greetings from Munich!
Manfred / lini
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