6550
6550 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $70.00 per tube.
Construction
The 6550 is a beam pentode power amplifier tube primarily designed for audio service, as described in the Tung-Sol datasheet. It has a heater rated at 6.3 volts and 1.5 amperes.
Ratings
The tube has a plate dissipation rating of 42 watts. Maximum plate voltage is 660 volts DC. In pentode connection, maximum grid 2 voltage is 440 volts DC; in triode and ultra-linear connection, maximum grid 2 voltage is 500 volts DC. Maximum grid 1 voltage ranges from -300 to 0 volts DC. Maximum continuous grid 2 dissipation is 6.0 watts, with a maximum of 10.0 watts for intermittent music or speech peaks. Maximum cathode current is 190 mA DC. Maximum grid 1 circuit resistance is 50 kohms with fixed bias and 250 kohms with self bias. Maximum bulb temperature is 250 °C. Maximum heater-cathode voltage with heater negative with respect to cathode is 300 volts total DC and peak; with heater positive with respect to cathode, it is 100 volts DC and 200 volts total DC and peak.
Capacitances
The 6550 has a grid 1 to plate capacitance of 0.8 pf, an input capacitance of 15 pf, and an output capacitance of 10 pf.
Applications
The tube is rated for push-pull amplifier designs up to 100 watts output.
| Measure | Per tube |
|---|---|
| Median | $70.00 |
| Typical range (25th–75th) | $50.00 – $107.55 |
| Most sales (10th–90th) | $35.00 – $209.27 |
| Extremes incl. outliers | $4.02 – $803.59 |
| Completed sales | 363 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Tung-Sol | $81.75 | $63.00 – $150.00 | 105 |
| GE | $76.10 | $64.60 – $86.50 | 61 |
| RCA | $90.00 | $67.50 – $115.95 | 38 |
| Svetlana | $54.62 | $38.74 – $68.40 | 24 |
| Sovtek | $52.04 | $38.96 – $65.90 | 21 |
| Genalex/Gold Lion | $98.88 | $50.00 – $284.99 | 21 |
| Electro-Harmonix | $56.12 | $48.75 – $68.33 | 20 |
| Sylvania | $75.00 | $60.00 – $107.50 | 9 |
| Shuguang | $41.49 | $39.10 – $370.00 | 5 |
| JJ | $17.50 | $16.25 – $61.45 | 4 |
| Philips | $107.55 | $101.52 – $114.03 | 3 |
| GEC | $456.91 | $181.50 – $456.91 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $95.53 | 107 |
| used | $65.12 | 150 |
| current | $63.00 | 61 |
Per-tube prices from completed sales, 2025-11-30 to 2026-10-18. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 6550, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Tung-Sol | 6550 | PDF (411 KB) |
| RCA (HB3) | 6550 | PDF (132 KB) |
Documents held here and used to write this page.
- - TUNG-SOL -