Fosi Audio Box X5 Phono Preamp Review

[SMen]

Your assumption afaik is right!

Yes ... but you can always spend 350 euros or more on an ultrasonic cleaner and those ticks and pops are no longer inevitable.

 

[Toni Mas]

I have found no indication about input impedance value for MM and MC cartridge...

 

[cfwotzka]

I have found no indication about input impedance value for MM and MC cartridge...

MM 47k, MC 100R

 

[Mulder]

Does it have a rumble filter?

 

[Mulder]

It would be very nice to se a review of this here at ASR. https://jdslabs.com/product/atom-phono/

 

[Juhazi]

This is available with some others, or are you asking for Fosi to offer it?

Fosi X5 natually, this thread is about it. I could even pay 5€ extra for it, no switch needed!

I do have a low budget preamp with filter. As well some integrated amps have it.... but now I need a new/second preamp for my living room system. Cables from deck must be 3m long, so external preamp is mandatory. ProJect Phono Box S2 is much more expensive. My cartridges are all MM

 

[JeremyFife]

Thank you for the review.

What a cracking little box: neat, inexpensive and measures really well. I'm enjoying Fosi's simple but effective designs too - who knew I'd like orange so much!

I keep telling myself I'm over vinyl ... and now I'm wondering about an office turntable setup. I need to have a word with myself.

 

[Billy Budapest]

@Fosi Audio
Thank you for this nice product.
Maybe Fosi wants to whip out an ASR discount, because now, many of us need a new phono-stage

I mean, the thing is $100. Do you really need a discount? The margins on this can’t be great so I don’t know how much further Fosi could nudge the price down anyway without losing money.

 

[Michael Fidler]

Very nice work. Credit where credit's due in spite of competition!

I'm guessing from my own experiments with similar results that this is based on an NJM4580 front end.

 

[SMen]

Very nice work. Credit where credit's due in spite of competition!

I'm guessing from my own experiments with similar results that this is based on an NJM4580 front end.

You should get an MM Pro across the Atlantic ... I sing your active loading's praises ...

 

[amirm]

I've been wondering, does the Audio Precision analyzer have a test routine for (phono) preamps like this or is it the standard test routine you're using @amirm ?

I don't know if they ever had scripts for phono stages but they certainly don't have one now. I have developed these tests over time. Fortunately AP still has reverse RIAA equalization which is critical in these tests. I wouldn't be surprised if at some point they delete that functionality.

 

[amirm]

Just confirming as was mentioned, I don't have ranking for MC only phono stages.

 

[peniku8]

I don't know if they ever had scripts for phono stages but they certainly don't have one now. I have developed these tests over time. Fortunately AP still has reverse RIAA equalization which is critical in these tests. I wouldn't be surprised if at some point they delete that functionality.

Interesting! How is the reference level of the generator for these tests adjusted inside the AP? You need a very low-level sweep to test these devices after all. Does it have relais that put resistors in the signal path?

 

[Amperage]

When can I get a unit with built-in rumble filter (highpass)?

View attachment 420531

Zen Phonos have rumble filters, IIRC.


Really interested in this (X5). It looks great.

 

[EERecordist]

This is a review and detailed measurements of the Fosi Audio Box X5 stereo Phono stage. It was sent to me by the company and costs US $109.99.
View attachment 420488
Company manages to bring a touch of class in a category that is universally utilitarian with those rounded corners and orange power button. Flexibility is provided by supporting both Moving Magnet (MM) and Moving Coil cartridges with different gain settings:
View attachment 420489

The gain setting is sandwiched tightly between the input and output RCA jacks. But company has wisely put in a tall knob to allow for relatively easy adjustment.

I forgot to take a picture of the AC transformer that is rated at indicated 16 volts.

Fosi Audio Box X5 Phono Measurements
It was quite a pleasant shock to see complete lack of distortion in our dashboard resulting in superb level of performance:
View attachment 420490

If the mains noise was not there, it would likely do even better. As is, it essentially ties with the best phono stage tested:
View attachment 420491

Moving coil at much higher gain naturally has more noise but still respectable:
View attachment 420492

Also impressive and very important, RIAA equalization is superbly done:
View attachment 420493

What's more there is good bit of headroom into treble region (my standard is > 100 mv @ 1 kHz):
View attachment 420494

Measuring distortion alone, we see that it is vanishingly low, at the level of good DACs and much better than many phono stages:
View attachment 420495

Conclusions
There are a lot of value oriented phono stages. Fosi innovates by bringing best in class performance while packaging the unit in an attractive enclosure while keeping the cost very reasonable. There is nothing more to ask!

I am happy to recommend Fosi Box X5 phono stage.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

A long time ago I built my own phono preamp from an AES article using discrete transistors. So I'm always interested in updated designs. I did an image search for Fosi Audio Box X5 teardown with no success. Very good performance.

 

[AudioSceptic]

Very nice work. Credit where credit's due in spite of competition!

I'm guessing from my own experiments with similar results that this is based on an NJM4580 front end.

The low price of the Fosi tells us that that the components can't be too expensive, just that they've optimised them with SOTA design. It must be tough competing with things like this, even though you do offer more.

 

[AudioSceptic]

Just confirming as was mentioned, I don't have ranking for MC only phono stages.

So the Classic Audio MC should be in your list, regardless?

 

[countbasey]

i have a parasound jc 3 jr i use in my system. They claim "signal-to-noise ratio of up to 94 dB, with a THD less than 0.02%".. wonder how it measures on Amir's bench?

 

[renaudrenaud]

Thank you for the review.

What a cracking little box: neat, inexpensive and measures really well. I'm enjoying Fosi's simple but effective designs too - who knew I'd like orange so much!

I keep telling myself I'm over vinyl ... and now I'm wondering about an office turntable setup. I need to have a word with myself.

It is lot of fun but you have to spend some money in this. A nice turntable, a good cartridge, a phono preamp.

Then comes the cleaning brush. Add a new mat, a protractor, an ultrasound cleaning machine, and the records. Don't forget these little bubble levels and the cartridge weight gauge.

Every 20 minutes you need to move because it is time to listen to B side or another record.

Yes, not comfortable, expansive and the quality is far below what you can have with some inexpensive DAC.

Maybe the same mental process as smoking. It is killing you but you like it.

 

[Mulder]

It is killing you but you like it.

Really? :-(