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Fosi Audio was founded with a simple goal: Build products that sound great and make people want to listen to music every day. We design, manufacture, and market many Hi-Fi audio products. We pursue your perfect music journey. Enjoy Hi-Fi music with Fosi Audio audio products!
5725W Vacuum Tube Phono Preamp/Headphone Amp
Product Parameters:
- Input Interface: MM turntable input, 3.5mm AUX input, 12V DC input
- Output Interface: RCA output, 3.5mm headphone output
- Output: Active(powered) speakers, Amplifier, Headphones
- Applicable headphone types: 16 Ω - 300 Ω
- Output Voltage Level: 1kHz and 650mV
- SNR: ≥ 70dB
- THD: ≤0.1%
- Frequency Response: Standard RIAA
- Product Adapter Input Voltage Range: AC 110V - 240V
Experience greater control over sound quality with the independent gain rotation design for treble and bass. This feature adds more playability and fun to your music, offering more ways to enjoy and explore.
The 3.5mm headphone output interface is compatible with standard headphones, providing dedicated functionality for headphone users. Additionally, the gain interface is specifically reserved for audiophile DIY. This preamp is designed to restore sound with greater clarity.
Equipped with 5725w vacuum tubes, this preamp offers a smoother listening experience, replicating the natural sound and retaining classic acoustic tones in audio equipment. The result is beautiful Hi-Fi sound quality. Furthermore, the 5725 tubes can be substituted for 6K4/6J1/6J4/6AK5/66*In vacuum tubes to cater to the specific needs of audiophiles.
The record preamp is compatible with moving-magnet (MM) cartridges and features precise RIAA equalization for accurate audio reproduction. Its exceptional sonic performance ensures consistent quality, while low noise enhances the overall listening experience.
This compact preamp features stereo RCA inputs and outputs, enabling you to easily connect your turntable to the preamp using the RCA inputs and ground.
The preamp's power supply is equipped with short-circuit protection and overload protection features. It is designed to effectively reduce the impact of AC input for enhanced safety and stability.
Bigstuff
2025-08-05 14:33:37
I needed a preamp because I couldn't do what I wanted with my existing setup. I had Fluance RT-85 turntable > Onkyo TX-SV575 (25 years old) > Rockville 21-band graphic EQ via Tape 2 monitor > Wharfdale Diamond 7.2 bookshelf speakers (also 25 years old). This setup sounded great, but I also want to have the music play in other rooms in perfect synchronization. I use the Wiim streaming device for this. The issue is that with that is that the sounds lagged a noticeable few milliseconds in the other rooms. The Wiim synch feature didn't work because the source setup didn't have the signal come from the Wiim. I need to change the order of the signal chain so that the turntable signal passed through the Wiim then to the receiver. And that's why I needed a pre-amp. After a night of researching solid state and tube preamps, I decided on the Fosi Box X4. I ordered it after 3am and it arrived before 6pm that same day (nice job, Amazon!). Set up was easy. The only odd thing was that the grounding post on the X4 is spring-loaded mechanism that seems intended for bare wire or a pin rather than the spade connector that is common on turntables. So I fed one prong of th fork into the opening and that works fine. The chain is now turntable > preamp > EQ > Wiim > receiver. This works but the sound seemed a little off. especially on older records. If I spent more time adjusting the EQ, I could probably get the sound to where I want it, but I'm lazy. Then it hit me, the sound out of the preamp to the receiver should be very good, so I set the EQ to direct mode which bypasses the adjustments of the EQ. I had to up the gain on the preamp after this since the EQ was boosting the level. Voila! That did it. Everyone is right that the X4 presents a wide and immersive soundstage. All the different pieces of percussion, acoustic and electric bass, piano, guitars, and vocals are all smooth and clear. I may keep this as the regular set up bypassing the EQ, and just using the EQ on tape and CD. This is my first tube set up, so I don't think I'll be making and tube changes for now. Definitely a great product, great performance, at a great price. I recommend it.
Matt Yates
2025-07-22 10:21:29
If you want a phono preamp and love the sound and visual appeal of tube's, the Fosi seems to be great for it's price. I combined this with my Fluance turntable, Yamaha amplifier, and Klipsch speakers and ive been very happy.
Steve K
2025-07-13 11:17:35
The phono preamp sounds surprisingly great with every cartridge I throw at it. Plenty of detail, punch, warmth but not dull at all, with a nice quiet background, too. The tone controls are legitimately useful, with logically-chosen frequencies for a change. The X4 is worth the price for the phono preamp alone, imo. But the headphone output sounds boxy. It's tinny, lacking low end AND high end. It might come in handy if you need a basic monitoring function but that's about it. One other thing I don't like; the cheesy lights that make the tubes glow unnaturally. Totally unnecessary. They could have taken the money they spent trying to make this preamp more appealing to gamers and spent it on better circuitry for the headphone out.Overall I'd give the Box X4 2.5 overall stars because of the headphone output and fake lights. However, the phono preamp itself sounds SO GOOD that I have to up it to 4 stars. This preamp easily outperforms the phono preamps in my Denon receiver, my Denon mixer, and my Pioneer 250MKII mixer. If you buy it for that and not for the headphone amp I think you'll be pleasantly surprised if not shocked!
R Sack
2025-07-09 17:20:44
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JOSÉ L.
2025-06-15 14:52:42
Gostei muito do produto, pois ampliou bastante a qualidade no som do meu vinil.
Dan Serray
2025-04-24 15:24:24
Well, discovered this product searching out a way to hook my old turntable to my Onkyo receiver that didnt have phono hook up. These popped up and i thought id give this one a try....well, these work excellent.I liked this one because it had separate volume and tone controls.....all good..Thanks guys
Javier Vázquez Castillo
2025-03-24 13:50:38
El amplificador lo adquirà para poder utilizarlo con mi tornamesa Onkyo CP-1050, al cual al principio la quise conectar con un AVR Yamaha y simplemente no se escuchaba nada !!!!, lo que era de esperarse ya que la salida de la tornamesa no estaba amplificada; sin embargo, tenÃa la esperanza de que funcionara. De ahà estuve revisando por varios dÃas que tipo de pre-amplificador deberÃa utilizar para conservar la calidad del sonido. Varios audiófilos recomendaron el Fosi, como un pre-amplificador de entrada si se desea escuchar buen audio (eso fue determinante para excluir al Pyle y al Behringer que son per-amplificadores muy económicos con respecto al Fosi). En ese sentido decidà adquirirlo, y no me decepcionó, el sonido suena muy claro y nÃtido (y eso que para pruebas lo he conectado de forma rápida a un minicomponente yahama de serie baja y a unos audÃfonos). Ademas, tiene control de encendido, control de altos y bajos. He escuchado diversos géneros de música y en todos suena bastante bien. Además, tiene un tipo Jack para tierra el cual funciona bastante bien eliminando todo el ruido no deseado, haciendo que la música suene limpia. Espero probarlo con mi AVR Yamaha y seguramente sonará igual de bien. Por otra parte debes considerar cables RCA a RCA que irán del pre-amplificador al receptor, no los trae. Yo adquirà unos de la ma marca KabelDirekt.
Arfpix
2025-02-24 15:55:37
Produit conforme aux attentes.
Curtis Newton
2025-01-27 13:04:48
Nachdem mein guter Onkyo-Receiver mit Phono-Anschluss das Zeitliche gesegnet hat, habe ich meinen 80er Jahre Technics-Plattenspieler lange an einem Vorverstärker für 20 DM aus den 90er Jahren am Denon AV-Receiver betrieben. Der Sound war o.k., kam natürlich nicht an den Onkyo ran. Nach einer Kabelverlängerung vom Vorverstärker zum Denon hatte ich, trotz angeschlossenem Massekabels, ständig Brummen, wenn keine Musik abgespielt wurde.Das Brummen ist nun mit dem Fosi verschwunden und der Ton wurde deutlich aufgewertet.Er erzeugt einen wunderbar warmen Klang, den ich mit verschiedenen Musikrichtungen getestet habe. Ich bin mega begeistert, denn ich habe eine Verbesserung erwartet und die wurde noch übertroffen. Für den Preis definiv eine Empfehlung wert.
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