7591
7591 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $49.20 per tube.
The 7591 is a power output tube contained in a T-9 envelope, as described in the Sylvania datasheet.
Ratings
The 7591 has a heater voltage of 6.3 volts and a heater current of 0.8 amperes. Maximum heater-cathode voltage is 200 volts total DC and peak with the heater negative with respect to the cathode, and 100 volts DC or 200 volts total DC and peak with the heater positive with respect to the cathode. The maximum plate voltage rating is 550 volts, the maximum grid No. 2 voltage rating is 440 volts, the maximum plate dissipation rating is 19 watts, and the maximum grid No. 2 dissipation rating is 3.3 watts. The maximum cathode current rating is 85 mA. Maximum grid No. 1 circuit resistance is 0.3 megohms for fixed bias and 1.0 megohms for self bias. The datasheet states that grid No. 2 dissipation may be permitted to reach 6 watts during periods of maximum input of speech and music signals. The input capacitance is 10 μμf and the output capacitance is 5.0 μμf. The datasheet specifies a mounting position of any.
Applications
In push-pull Class AB1 operation, the 7591 can furnish 43 watts of power output at very low distortion. In ultra-linear operation at 400 volts plate voltage, the 7591 provides 32 watts of power output with a load resistance (plate to plate) of 6600 ohms and a total harmonic distortion of 1.0 percent. In pentode operation at 425 volts plate voltage, the 7591 provides 26 watts of power output with a load resistance (plate to plate) of 6600 ohms and a total harmonic distortion of 2 percent. In triode-connected operation at 300 volts plate voltage, the 7591 has a transconductance of 10.2K μmhos, a plate resistance of approximately 29K ohms, a load resistance of 3K ohms, a power output of 11 watts, and a total harmonic distortion of 13 percent.
Construction
The datasheet states that grid No. 2 connections, pins 4 and 8, should be externally tied together for efficient operation. The datasheet was prepared and released by the Technical Publications Section, Emporium, Pennsylvania, in October 1961.
| Measure | Per tube |
|---|---|
| Median | $49.20 |
| Typical range (25th–75th) | $36.00 – $64.99 |
| Most sales (10th–90th) | $26.57 – $85.80 |
| Extremes incl. outliers | $6.58 – $681.24 |
| Completed sales | 267 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Westinghouse | $56.96 | $46.45 – $74.50 | 52 |
| Sylvania | $50.00 | $44.99 – $61.02 | 44 |
| GE | $47.00 | $40.00 – $61.65 | 39 |
| RCA | $48.02 | $37.50 – $66.00 | 30 |
| JJ | $26.29 | $22.33 – $28.57 | 15 |
| Tung-Sol | $57.09 | $46.25 – $133.42 | 12 |
| Electro-Harmonix | $31.80 | $31.00 – $36.38 | 9 |
| Toshiba | $49.24 | $35.82 – $60.00 | 5 |
| Sovtek | $31.42 | $29.00 – $36.70 | 4 |
| Philips | $45.00 | $40.00 – $49.00 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $56.42 | 64 |
| used | $49.50 | 141 |
| current | $32.55 | 25 |
Per-tube prices from completed sales, 2025-08-01 to 2026-10-17. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 7591, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Sylvania | 7591 | PDF (435 KB) |
| Tung-Sol | 7591 | PDF (95 KB) |
Documents held here and used to write this page.
- engineering data service