Fosi Audio Box X5 Phono Preamp Review

[Mudflapper]

I agree. In fact the Box X4 sounds shockingly good as well despite the lower SNR spec on paper. It's exciting that we no longer need to spend $500+ for a great-sounding standalone phono preamp. I liked the X4's sound so much I bought another and used them for my home DJ setup because Pioneer and Denon mixers, at least the ones I've owned, have dull-sounding afterthought phono pres stuffed into them. Now I have a proper Allen & Heath PX5 with great phono pres for mixing, and for hi-fi I use the pre in the Nakamichi TA-4A which sounds gorgeous. I'll probably sell the X4's here or on Reverb when I can find the time.

 

[Laika2]

Recently, my son was given a Technics SL-1500 turntable by a friend. So I set it up for him at his place. I gave him my old Sony HTR 5.1 (STR-DH550 / 80 watts per channel) and a pair of Sony 60 watt bookshelf speakers. My wife found a used AV rack for $10 bucks at our local Goodwill. The HTR didn’t have built-in turntable support, so I dropped $100 on this Fosi X5 turntable preamp via Amazon. I put an old blanket under the speakers on the bottom shelf to dampen any vibrations.

I was astounded at the gorgeous sound emanating from this thrown-together system. Highly recommend the Fosi X5 turntable pre-amp, easy setup & terrific sound.

Perhaps the best bargain in phono preamp, I replaced mine with a Waxwing (for a few extra features I wanted). I've had many phono preamps in the $500 + range the X5 sounded as good as any (if you don't use the Waxwings tone controls).

I kept the 2 X5s in case one of my Waxwings go down. The X5 is amazing for the price and unlike other low cost high performance audio products there are very few that had issues (some early ones had a channel imbalance right out of the box and we're replaced for free if bought on Amazon.

I've moved on but the X5 is the gold standard of price vs performance.

 

[Victorr_]

I didn't read the whole topic. There were questions about input capacitance. Maybe there was an answer. If not, then here it is - 100 pF

 

[Lux Maldini]

I didn't read the whole topic. There were questions about input capacitance. Maybe there was an answer. If not, then here it is - 100 pF

We are very sorry that we didn't clarify this earlier, which may have caused some misunderstanding. In fact, the input capacitance of the BOX X5 is 150 pF.

 

[Victorr_]

We are very sorry that we didn't clarify this earlier, which may have caused some misunderstanding. In fact, the input capacitance of the BOX X5 is 150 pF.

100 pf - I got this value when communicating with the AI. He, as it happens, was mistaken. Thank you for the clarification. This is important.

 

[antcollinet]

100 pf - I got this value when communicating with the AI. He, as it happens, was mistaken. Thank you for the clarification. This is important.

Here is some advice - don't use AI without fact checking the answers. If it can't provide a reference link - don't believe it.

 

[Ropeburn]

Here is some advice - don't use AI without fact checking the answers. If it can't provide a reference link - don't believe it.

More free advice: if you have to fact check, skip AI and go straight for the facts yourself.

 

[Victorr_]

Yes, I know. Colleagues, artificial intelligence is discussed in another topic.

 

[antcollinet]

Yes, I know. Colleagues, artificial intelligence is discussed in another topic.

If you are aware of that thread, then you should know the requirement for following the AI related policy when quoting AI in your posts.

 

[EJ3]

100 pf - I got this value when communicating with the AI. He, as it happens, was mistaken. Thank you for the clarification. This is important.

AI (so far) means "FREQUENTLY WRONG"!

 

[Ropeburn]

AI (so far) means "FREQUENTLY WRONG"!

How about Always Inaccurate

 

[EJ3]

How about Always Inaccurate

Not willing to go that far, as, occasionally, it stumbles in a correct direction, like a child learning to walk.

 

[antcollinet]

Not willing to go that far, as, occasionally, it stumbles in a correct direction, like a child learning to walk.

I find it helpful more often than not. But I tend not to use it just to ask for single factual information.


It is particularly helpfull when you "work with it" in dialog form. Treating it as a "competent colleague" but not expecting it to have all the right answers at first go.

Works very well for diagnosis and fix situations as I (and others) have described in the appropriate thread (which is where these posts should head as hinted at by @Victorr_ ).

 

[Victorr_]

Yes, AI is still a child, using the most accessible (and often the least reliable) sources of information. A few days ago I had a dialogue with him. I suggested that AI compare Parasound Zphono (I have one) and Fosi Audio Box X5 (which I bought and it is still on its way to me).
At first, AI noted that Zphono is undoubtedly better in all respects. In particular: linear power supply, circuit on discrete elements, reliable metal case. And Box X5, in his opinion, is a cheap Chinese product with a flimsy case, switching power supply and poor-quality elements in the circuit.
I drew AI's attention to the errors in his conclusions regarding Zphono (not a discrete circuit), as well as Box X5 (linear power supply, metal case and high-quality elements in the circuit). HE admitted the error and noted that Box X5 is actually not that bad.
Then I gave him a link to Amir's reviews of both devices...
After analyzing the AI, he was extremely verbose. I will not repeat everything he wrote to me. His final conclusion was this: Zphono is a reliable classic from the 70s that does not meet modern requirements . Box X5 is a great example of modern uncompromising quality at very affordable prices..

Separately, I will say about the price of Chinese products.
China is a communist party "monarchy". The Chinese government has set itself the task of capturing markets around the world. The Western world gave them technology for free when it placed all its production there. At the moment, the Chinese government provides quite significant financial support to manufacturers that export goods. Given this support and cheap labor, prices can be 2-3 times lower than they should be.
I think that after they destroy competitors outside China, the prices for their products will not please us at all.

 

[Chasepoes]

I've read several posts on this forum about the influence of the input impedance on the performance of an MC cartridge. Some say it makes a big difference, others tend to say it doesn't matter that much in the grand scheme of things. The rule of thumb being that the input impedance of the phone stage should have a 1:10 ratio to the impedance of the cartridge. The cartridge I'm using in my turntable (DL-301 MK2) has an internal resistance of 33 Ohms. So the input impedance of the pre-amp should be around 330 Ohms. The impedance of the X5 is 100 Ohm (MC mode).

I've looked inside the box and found a 100 Ohm resistor on the input on every channel (and a 47k when in MM mode). Although these are small SMD resistors I could change out the two 100 Ohm resistors for 330 Ohm resistors. But I'm wondering if it is worth the effort and if altering the input impedance of the X5 would have any impact on its performance.


Can anyone share some meaningful insight on this?

 

[Ropeburn]

I've read several posts on this forum about the influence of the input impedance on the performance of an MC cartridge. Some say it makes a big difference, others tend to say it doesn't matter that much in the grand scheme of things. The rule of thumb being that the input impedance of the phone stage should have a 1:10 ratio to the impedance of the cartridge. The cartridge I'm using in my turntable (DL-301 MK2) has an internal resistance of 33 Ohms. So the input impedance of the pre-amp should be around 330 Ohms. The impedance of the X5 is 100 Ohm (MC mode).

I've looked inside the box and found a 100 Ohm resistor on the input on every channel (and a 47k when in MM mode). Although these are small SMD resistors I could change out the two 100 Ohm resistors for 330 Ohm resistors. But I'm wondering if it is worth the effort and if altering the input impedance of the X5 would have any impact on its performance.


Can anyone share some meaningful insight on this?

I don't know about the exact performance difference of input resistors - others will be able to help you with the details.

But generally, if you're going to change the resistors, you could make it switchable while you're at it. If you manage to solder wires to the resistor pads - fiddly but doable. Then put say a three-position miniature switch into the case, and wire three different pairs of resistors with values as desired.

Of course only advisable if you know what you're doing. Can you provide inside pictures? I suspect it's all small enough for making damage easy - but it's an idea.

 

[Chasepoes]

The second image is a close-up of the left top corner. The blue arrows poin to the two groups of 100 and 47K Ohm resistors. Plenty room to make switchable resistors a thing.

 

[Ropeburn]

View attachment 532130View attachment 532133


The second image is a close-up of the left top corner. The blue arrows poin to the two groups of 100 and 47K Ohm resistors. Plenty room to make switchable resistors a thing.

Oh nice, that looks doable. Could use those big thruhole pads at least for one side. If you're good with your hands it shouldn't be too hard.

 

[Chasepoes]

Well I've mounted 2 330Ohm resistors in place of the original 100 Ohms and will see if it makes any difference. Any perceived differences will be purely subjective, because I lack the equipment to measure the results. But if it didn't mess op the sound I at least have the piece of mind that my cartridge is loaded correctly.

 

[shivver]

Guys, after reading this thread I decided to go for X5 and it sounds great to me, but I have an issue with provided power unit, it makes a buzzing sound when not in use and stays hot even though X5 is off. Is it common issue? Any fix or should I return it? Thanks