Fosi Audio BT20A ProvsOldchen (Laochen) EL34-B
A detailed side-by-side comparison of the Fosi Audio BT20A Pro and Oldchen (Laochen) EL34-B — two popular amplifiers in the Chinese HiFi space.
Specifications
Spec
Fosi Audio BT20A Pro
Oldchen (Laochen) EL34-B
Class
D
A
Chipset
TI TPA3255
—
Power
2 × 300W @ 4Ω
10W x 2
Inputs
RCA, Bluetooth 5.0
—
Features
Tone Controls with center detent (bypass), Pre-Out
—
Topology
—
Single Ended Triode (SET)
Tubes
—
EL34 x2, 6N9P x2, 5U4G x1
Wiring
—
Point-to-Point (Hardwired)
Remote Control
✗
✗
Tube Stage
✗
✓
Price (estimated)
Price
~$76
~$170
Difference
~$94.00 cheaper (Fosi Audio BT20A Pro)
Things to Know
Fosi Audio BT20A Pro
- ⚠Bluetooth is always active; anyone can pair with it if you don't disconnect.
- ⚠Tone controls can introduce slight phase shift even at center detent.
- ⚠Pre-out level is low compared to industry standards.
Oldchen (Laochen) EL34-B
- ⚠The '5U4G' rectifier is often wired in hybrid mode with silicon diodes, which purists dislike.
- ⚠Transformers run very hot, suggesting they are pushed near their saturation limits.
- ⚠Stock Chinese EL34 tubes can sound harsh compared to budget re-issues like Mullard or JJ.
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