1760H Hammond PP Übertrager Deluxe Reverb 125A1A Fender

Hammond 1760H – Deluxe Reverb output transformer for 125A1A / 022640

The Hammond 1760H is a paper-wound, centre-tapped push-pull output transformer for valve guitar amplifiers. It provides a 6.6 kΩ plate-to-plate load, a 20 W transformer rating and secondary outputs for 4, 8 and 16 Ω. It is suitable for compatible Deluxe and Deluxe Reverb output stages using a pair of 6V6 valves and for correctly designed new builds.

Hammond lists the 1760H for Fender reference numbers 125A1A, 022640 and 041318. These numbers support technical identification but do not provide universal installation approval. The amplifier revision, schematic, mounting pattern, speaker load and negative-feedback circuit must match the specific amplifier.

Suitable applications

• Repair and restoration of compatible Deluxe and Deluxe Reverb amplifiers
• Applications associated by Hammond with Fender references 125A1A, 022640 and 041318
• Push-pull output stages using two 6V6 valves and a nominal 6.6 kΩ plate-to-plate load
• New builds requiring selectable 4, 8 or 16 Ω speaker connections
• Replacement of a Hammond 1750H when additional secondary taps are required

Technical data

Product type

Push-pull output transformer for valve guitar amplifiers

Manufacturer application reference

Deluxe and Deluxe Reverb; Fender reference numbers 125A1A, 022640 and 041318

Primary impedance

6.6 kΩ plate-to-plate, centre-tapped

Secondary impedances

4, 8 and 16 Ω

Transformer power rating

20 W

Winding construction

Paper wound

Frequency response

70 Hz to 15 kHz, 0/-1 dB referenced to 1 kHz

Primary inductance

25.8 H typical at 1 kHz, 1 V with the secondary open

Leakage inductance

12.30 mH typical at 1 kHz, 1 V with the secondary shorted

Primary DC resistance

347.8 Ω between brown and blue, typical

Secondary DC resistance

0.686 Ω black–yellow, 0.803 Ω black–green and 1.157 Ω black–white, typical

Dielectric strength

1,500 V RMS

Temperature range

-40 to +105 °C

Construction

Open-frame chassis mounting

Flying leads

Primary and secondary leads at least 9 in or approximately 229 mm long

Dimensions

Approx. 93.7 × 61.0 × 58.6 mm according to drawing dimensions A × B × C

Mounting

Approx. 79.4 mm mounting centres; mounting-hole diameter approx. 4.75 mm

Shipping weight

Approx. 0.73 kg according to Hammond

Connections

Primary winding

Brown and blue to the two output-valve plates, red centre tap to the high-voltage supply

4 Ω output

Black common and yellow 4 Ω tap

8 Ω output

Black common and green 8 Ω tap

16 Ω output

Black common and white 16 Ω tap

Comparison with the Hammond 1750H

Hammond 1760H

6.6 kΩ plate-to-plate, 20 W, paper wound, with 4, 8 and 16 Ω outputs

Hammond 1750H

6.6 kΩ plate-to-plate, 20 W, paper wound, with an 8 Ω output only

Selection and installation notes

Fender numbers 125A1A, 022640 and 041318 are transformer references documented by Hammond. They do not replace verification of the actual circuit and should not be confused with chassis designations such as AB763.

Connect the speaker to the tap carrying the same nominal impedance. An 8 Ω speaker connected to the 4 Ω tap approximately doubles the reflected primary load to 13.2 kΩ plate-to-plate. A 4 Ω speaker connected to the 8 Ω tap approximately halves it to 3.3 kΩ. A mismatch changes current, output power and distortion behaviour and should not be used without checking the complete output stage.

The 20 W figure is the transformer's rating and is not the same as the amplifier manufacturer's stated output power. Hammond also lists the 1760H for Deluxe Reverb applications whose amplifier output is rated at 22 W.

In amplifiers using global negative feedback, check the selected secondary tap and transformer phase. Reversed primary connections can turn negative feedback into positive feedback. Insulate every unused secondary lead separately.

Lethal voltages may be present on the primary wiring. Installation and testing require suitable expertise, a disconnected mains supply, safely discharged filter capacitors, touch protection and adequate insulation clearances.

Questions about selection and use

Which output transformer suits a two-6V6 Deluxe Reverb output stage associated with references 125A1A or 022640?

Hammond 1760H is the documented multi-tap reference for this application. It provides a 6.6 kΩ plate-to-plate load, a 20 W rating and speaker outputs for 4, 8 and 16 Ω. Check the amplifier revision, mounting and feedback circuit before installation.

Which output transformer provides 4, 8 and 16 ohm speaker taps for a 6.6 kΩ push-pull stage?

Hammond 1760H combines a 6.6 kΩ centre-tapped primary with separate 4, 8 and 16 Ω outputs at a 20 W transformer rating. Connect the speaker between black common and the appropriate yellow, green or white tap.

Can the Hammond 1760H replace the Hammond 1750H?

Yes, the Hammond 1760H can replace the Hammond 1750H in compatible circuits because the primary impedance, transformer rating and paper-wound construction match. The 1760H adds 4 and 16 Ω outputs; mounting, wiring and feedback must still be checked.

Is the Hammond 1760H intended for Fender references 125A1A, 022640 and 041318?

Yes, Hammond explicitly lists the 1760H for Fender references 125A1A, 022640 and 041318. The numbers support part identification, but the exact amplifier version and its mechanical and electrical construction must still be compared.