Hammond 1640SEA 30W Single-Ended Tube Output Transformer, 1250 Ohm
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Create Free Business AccountKey Features
- 30 W single ended, Class-A tube output transformer
- 1250 ohm primary rated for 200 mA max DC bias
- Suited to parallel output tubes (300B, 2A3, 6550, 6CA7 and more)
- 4-8-16 ohm secondary with 40% Ultra-Linear screen tap
- 14 Henry primary inductance; 2000 VRMS hipot
- Shielded case with four slot chassis Type "X" mounting
The 1640SEA is a 30 watt single ended output transformer with a 1250 ohm primary and a 200 mA DC bias rating. Its suggested tube list is built around parallel operation, parallel 2A3, 6A3, 6B4G, 300B, 572B or 811A triodes, or parallel 6550 or 6CA7 pentodes, so it suits builders doubling up output tubes in a single ended design.
The 1627-1642 Series is "over designed" for high fidelity, single ended, Class-A tube output circuits. Each transformer is enclosed (shielded) and uses high quality (M6) grain oriented silicon steel laminations, with a gapped core to reduce core saturation in Class-A amplifier circuits. Insulated flexible leads are 8" minimum, and the case uses four slot, chassis Type "X" mounting with 0.20 x 0.38 in (5 x 10 mm) slots.
The secondary is tapped at 4, 8 and 16 ohms and a 40% screen tap allows Ultra-Linear operation if desired. Listed primary inductance is 14 Henrys. The drawing shows typical values of 28 ohm primary DCR, 3.2 Hy primary inductance and 19.95 k primary impedance at 1 kHz, with secondary DCR of 414, 520 and 728 milliohms. Frequency response is at least 20 Hz to 20 kHz at full rated power (+/- 1 dB max.); hipot test 2000 VRMS; temperature range -40 to 105C.
Overall dimensions are A 3.75 in (95 mm), B 4.94 in (125 mm), C 4.56 in (116 mm), D 3.00 in (76 mm) and E 3.81 in (97 mm). Weight is 11 lbs (4.99 kg). Made in Canada. RED to B+, BLUE to the plate, BLUE/YELLOW to the screen. RoHS and REACH compliant, UPC 623980008332.
Ideal For
- Parallel single ended 300B amplifiers
- Parallel 6550 / 6CA7 single ended amplifiers
- Ultra-Linear Class-A output stages
Wiring
| Leads | Insulated flexible leads, 8" min. |
| RED Lead | Connects to B+ |
| BLUE Lead | Connects to the tube plate |
| Secondary Leads | BLK - COM, GRN - 4 ohm, YEL - 8 ohm, WHT - 16 ohm |
| BLUE/YELLOW Lead | Connects to screen (optional use), 40% screen tap |
Mounting
| Mounting Type | Four slot, chassis Type "X" mounting |
| Mounting Slot (G) | 0.20 in (5 mm) x 0.38 in (10 mm) |
Overview
| Series | 1627-1642 Series, Tube Output (25 - 75 Watts) Single Ended - HI-FI |
| Circuit Type | Single ended, Class-A tube output (triode, tetrode or pentode tubes) |
| Product Type | Tube output transformer, single ended |
| Country Of Origin | Made in Canada |
| Short Description | AUDIO TX 1.25K OHM 30 WATT |
Dimensions
| Weight | 11 lbs. |
| Overall Dimension A | 3.75 in (95 mm) |
| Overall Dimension B | 4.94 in (125 mm) |
| Overall Dimension C | 4.56 in (116 mm) |
| Overall Dimension D | 3.00 in (76 mm) |
| Overall Dimension E | 3.81 in (97 mm) |
Electrical
| Test Note | Typical results, subject to normal manufacturing and electrical tolerances; graphs at 20 dBu input level |
| Hipot Test | 2000 VRMS |
| Audio Power | 30 Watts |
| Primary Impedance | 1250 ohms |
| Primary Inductance | 14 Henrys |
| Dielectric Strength | 2000Vrms |
| Secondary Impedance | 4-8-16 ohms |
| Primary Max. DC Bias | 200 ma. |
| Primary DCR (Blue – Red) | 28 Ω |
| Frequency Response (Series) | At least 20 Hz to 20 kHz at full rated power (+/- 1 dB max., ref. 1 kHz) |
| Frequency Response (Drawing) | Typ. 1.0 dB from 20Hz to 20KHz (see graphs) |
| Typical Output Power (Drawing) | 30 Watts |
| Secondary DCR Black – Green (4 Ohm) | 414 mΩ |
| Ultra-Linear 40% Primary (Screen) Tap | Yes |
| Secondary DCR Black – White (16 Ohm) | 728 mΩ |
| Secondary DCR Black – Yellow (8 Ohm) | 520 mΩ |
| Impedance, Black – Green (@ 1.0 KHz, 1.0 V OC) | 143 Ω |
| Impedance, Black – White (@ 1.0 KHz, 1.0 V OC) | 475 Ω |
| Impedance, Black – Yellow (@ 1.0 KHz, 1.0 V OC) | 264 Ω |
| Inductance, Black – Green (@ 1.0 KHz, 1.0 V OC) | 25.0 mH |
| Inductance, Black – White (@ 1.0 KHz, 1.0 V OC) | 82.2 mH |
| Inductance, Black – Yellow (@ 1.0 KHz, 1.0 V OC) | 46.0 mH |
| Impedance, Primary Blue – Red (@ 1.0 KHz, 1.0 V OC) | 19.95 kΩ |
| Inductance, Primary Blue – Red (@ 1.0 KHz, 1.0 V OC) | 3.2 Hy |
Identifiers
| UPC | 623980008332 |
| UNSPSC | 39121301 |
Suggested Tubes
| Triodes | Parallel - 2A3, 6A3, 6B4G, 300B, 572B, 811A |
| Pentodes | Parallel - 6550, 6CA7 |
Packaging & Shipping
| Shipping Weight | 11 lbs (4.99 kg) |
Construction & Finish
| Core | Gapped to reduce core saturation in Class-A tube amplifier circuits |
| Enclosure | Enclosed (shielded) |
| Laminations | High quality (M6) grain oriented silicon steel |
Environmental & Protection
| Temperature Range | -40 To 105C |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
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Frequently Asked Questions
Which tubes are suggested for the 1640SEA?▾
Parallel 2A3, 6A3, 6B4G, 300B, 572B or 811A triodes, and parallel 6550 or 6CA7 pentodes.
What is the DC bias rating of the 1640SEA?▾
200 mA maximum.
Does the 1640SEA have an Ultra-Linear tap?▾
Yes, a 40% primary screen tap on the BLUE/YELLOW lead.
What does the 1640SEA weigh?▾
11 lbs (4.99 kg).
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