2. EA13 Frequently Asked Questions

Q: Why are the left‑right swing angles of the EA13 VU meter inconsistent?

A: Minor angular deviation between the left and right channels is normal and perfect alignment cannot be achieved. Deviations of approximately ±1° come from manufacturing tolerances of the VU meter and sampling‑circuit errors. Please contact our engineers if you notice obvious discrepancies.

Q: How do I fix severe background noise from the EA13 PO output?

A: The EA13 is a tube amplifier and inherently produces background noise. Many circuit‑level optimizations have been applied. Nevertheless, avoid using highly‑sensitive small‑sized earphones; large‑size headphones are recommended for listening.

During playback, keep wireless‑emitting devices such as Wi‑Fi routers and mobile phones away from the EA13. Vacuum tubes are susceptible to such interference, which will worsen background noise.

Q: Why does the EA13 become hot during operation?

A: The EA13 adopts an optimized vacuum‑tube layout for a compact and attractive chassis, which slightly compromises heat‑dissipation performance. To achieve better sound performance, the vacuum‑tube circuit uses DC power supply, which generates more heat than an AC‑powered design. Please operate the unit in a well‑ventilated or air‑conditioned environment. Take care around hot surfaces.

Q: There is no pop noise on first power‑on, but pop noise occurs on consecutive power cycles. What causes this?

A: At initial cold startup, the EA13 produces no pop noise. When you power‑on again while the unit is still hot, pop‑noise transients will be amplified by subsequent stages. Allow a 1‑2‑minute interval between power‑off and power‑on for hot restarts.

Q: Why is there a slight odor when using the EA13?

A: Varnish is used during transformer impregnation; residual substances evaporate during unit burn‑in. Extended factory burn‑in has already removed most of the odor. The fumes are non‑toxic and comply with RoHS standards. For new‑unit use, play the EA13 in a well‑ventilated area for some time to dissipate residual odors.

Vacuum Tube Appearance Notes

1. Black or mirror‑like marks on the inner walls and top of vacuum tubes come from getter coatings; discoloration over usage time is normal.

2. Partial incomplete printing on tube housings may occur due to production‑era and storage conditions.

Neither of the above two conditions affects product quality or vacuum‑tube service life.