1760J Hammond PP Übertrager Pro Reverb Vibrolux 125A6A 35W

Hammond 1760J – 40 W output transformer for Vibrolux, Pro and related Fender stages

The Hammond 1760J is a bobbin-wound push-pull output transformer providing 4 kΩ plate-to-plate and secondary taps for 4, 8 and 16 Ω. It carries a 40 W transformer rating.

Hammond lists the 1760J for compatible Vibrolux, Vibrolux Reverb, Pro, Pro Reverb, Bandmaster and Tremolux versions. Documented references include 125A6A, 022848 and 125A7A.

Suitable applications

• Fender Vibrolux and Vibrolux Reverb amplifiers with a matching reference
• Fender Pro and Pro Reverb amplifiers in compatible chassis versions
• Documented Bandmaster and Tremolux circuits
• Push-pull output stages using two 6L6, 6L6GC or 5881 valves
• Total loudspeaker loads of 4, 8 or 16 Ω
• New amplifiers requiring approximately 4 kΩ in the 40 W transformer class

Technical data

Product type

Push-pull guitar-amplifier output transformer

Model

Hammond 1760J

Documented amplifier families

Vibrolux, Vibrolux Reverb, Pro, Pro Reverb, Bandmaster and Tremolux

Documented references

125A6A, 022848 and 125A7A

Primary impedance

4 kΩ plate-to-plate with centre tap

Secondary impedances

4, 8 and 16 Ω

Transformer power rating

40 W

Amplifier topology

Push pull

Typical output-valve complement

Two 6L6, 6L6GC or 5881 valves in total at a suitable operating point

Winding type

Bobbin winding

Primary inductance

Approx. 19.5 H at 1 kHz, 1 V and open secondary

Primary DC resistance

Approx. 185 Ω between brown and blue

Secondary DC resistance at 4 Ω

Approx. 0.356 Ω between black and green

Secondary DC resistance at 8 Ω

Approx. 0.502 Ω between black and yellow

Secondary DC resistance at 16 Ω

Approx. 0.910 Ω between black and white

Primary leakage inductance

Approx. 35.93 mH at 1 kHz, 1 V and short-circuited secondary

Frequency response

70 Hz to 15 kHz, 0/-1.5 dB referenced to 1 kHz

Distortion

Less than 1% at 70 Hz under the documented test conditions

Dielectric test

1,500 V RMS

Temperature range

-40 to +105 °C

Lead length

At least approximately 229 mm or 9 inches

Dimensions

Approx. 101.6 × 71.1 × 66.8 mm maximum

Mounting centres

Approx. 90.4 mm

Mounting-hole diameter

Approx. 4.7 mm

Hammond shipping weight

Approx. 1.81 kg

Lead connections

Brown

First primary connection to one output-valve plate

Red

Primary centre tap to B+

Blue

Second primary connection to the opposite output-valve plate

Black

Secondary common or loudspeaker ground

Green

4 Ω loudspeaker tap

Yellow

8 Ω loudspeaker tap

White

16 Ω loudspeaker tap

Selecting the loudspeaker tap

The selected secondary tap must match the total impedance of all connected loudspeakers. Insulate every unused lead separately.

The 4, 8 and 16 Ω leads are not three independently loadable simultaneous outputs. Calculate the complete impedance of a multiple-speaker system before connection.

Comparison with the Hammond 1750J

The Hammond 1750J has a fixed 4 Ω output with the same nominal 4 kΩ and 40 W ratings. The Hammond 1760J adds 8 and 16 Ω taps.

A service replacement must still match the reference, mounting, lead routing and feedback phase of the exact amplifier version.

Safety notes

Lethal voltage is present on the primary. Install the transformer with complete touch protection on a chassis capable of supporting its mass.

Questions about selection and use

Which output transformer suits a Vibrolux or Pro Reverb using 125A6A, 022848 or 125A7A?

Hammond 1760J is intended for these documented Fender applications and provides 4 kΩ plate-to-plate, 4/8/16 Ω taps, bobbin winding and a 40 W rating.

Which 40 W output transformer suits two 6L6 valves requiring 4 kΩ and several speaker impedances?

Hammond 1760J is a suitable starting point for a correctly designed two-6L6 or 5881 output stage requiring 4 kΩ plate-to-plate and a total load of 4, 8 or 16 Ω.

Can the Hammond 1760J be used in a compatible Bandmaster or Tremolux circuit?

Yes, the Hammond 1760J can be used in a Hammond-documented Bandmaster or Tremolux version when the reference, primary load, mounting and feedback phase correspond.

Is the Hammond 1760J a suitable alternative to the Hammond 1750J?

Yes, the Hammond 1760J can replace the 1750J in a compatible circuit and adds 8 and 16 Ω taps to the fixed 4 Ω output of the 1750J.