1750Y Hammond PP Übertrager AC15 Vox 6,2k 8 Ohm 15W EL84

Hammond 1750Y – 15 W output transformer for Vox AC15 Vintage

The Hammond 1750Y is a bobbin-wound push-pull output transformer for compatible Vox AC15 output stages. It provides a 6.2 kΩ plate-to-plate primary, a fixed 8 Ω loudspeaker output and a 15 W transformer rating.

Hammond documents the 1750Y for the AC15 Vintage and lists P-TVO15 as the comparison reference. A typical application uses two EL84 or 6BQ5 output valves.

Suitable applications

• Vox AC15 Vintage amplifiers with a matching transformer and chassis version
• Replacement applications around comparison reference P-TVO15
• Push-pull output stages using two EL84 or 6BQ5 valves in total
• New amplifiers requiring approximately 6.2 kΩ and an 8 Ω total load
• Guitar amplifiers in the 15 W transformer class
• Service projects requiring long flying leads

Technical data

Product type

Push-pull guitar-amplifier output transformer

Model

Hammond 1750Y

Documented amplifier application

Vox AC15 Vintage

Hammond comparison reference

P-TVO15

Primary impedance

6.2 kΩ plate-to-plate with centre tap

Secondary impedance

8 Ω

Transformer power rating

15 W

Amplifier topology

Push pull

Typical output-valve complement

Two EL84 or 6BQ5 valves in total at a suitable operating point

Winding type

Bobbin winding

Primary inductance

Approx. 14.6 H at 1 kHz, 1 V and open secondary

Secondary inductance

Approx. 31.04 mH at 1 kHz, 1 V and open primary

Primary DC resistance

Approx. 289 Ω between white and red

Secondary DC resistance

Approx. 0.480 Ω between black and green

Primary leakage inductance

Approx. 14.04 mH at 1 kHz, 1 V and short-circuited secondary

Frequency response

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

Distortion

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

Dielectric test

2,000 V RMS

Temperature range

-40 to +105 °C

Lead length

At least approximately 457 mm or 18 inches

Dimensions

Approx. 63.5 × 84.5 × 77.7 mm

Mounting dimensions

Approx. 47.6 × 60.4 mm according to the manufacturer drawing

Mounting slots

Approx. 4.7 × 9.4 mm

Hammond shipping weight

Approx. 1.81 kg

Manufacturing note

Made in Canada according to the current component drawing

Lead connections

White

First primary connection to one output-valve plate

Brown

Primary centre tap to B+

Red

Second primary connection to the opposite output-valve plate

Black

Secondary common or loudspeaker ground

Green

8 Ω loudspeaker connection

Phase

Follow the circuit of the exact AC15 version where global feedback is used

Fixed 8 Ω design

The nominal 6.2 kΩ plate-to-plate load is obtained with a total loudspeaker impedance of 8 Ω. The 1750Y has no additional secondary taps.

A 16 Ω load would ideally reflect approximately 12.4 kΩ, while a 4 Ω load would reflect approximately 3.1 kΩ. Use such mismatches only where the altered load deliberately suits the output stage.

Difference from AC30 output transformers

The Hammond 1750Y is a 15 W model for a two-EL84 output stage. Hammond 1750T and 1750V transformers are 30 W models for four-EL84 AC30 circuits and are not equivalent merely because they serve the same amplifier brand.

Safety notes

Lethal plate and signal voltages are present on the primary. Install the open transformer with complete touch protection and fully discharge the amplifier before service work.

Questions about selection and use

Which output transformer suits a Vox AC15 Vintage using P-TVO15?

Hammond 1750Y is documented for the Vox AC15 Vintage and comparison reference P-TVO15 and provides 6.2 kΩ plate-to-plate, a fixed 8 Ω output and a 15 W rating.

Which 15 W push-pull output transformer suits two EL84 valves requiring 6.2 kΩ and 8 Ω?

Hammond 1750Y is a suitable starting point for a correctly designed two-EL84 output stage requiring approximately 6.2 kΩ plate-to-plate and an 8 Ω total load.

Can the Hammond 1750Y be used in a newly designed EL84 push-pull amplifier?

Yes, the Hammond 1750Y can be used in a new amplifier when the 6.2 kΩ load, 8 Ω output, 15 W rating, plate and screen voltages and quiescent currents suit the EL84 circuit.

Is the Hammond 1750Y suitable for AC15 versions using a fixed 8 Ω output?

Yes, the Hammond 1750Y is suitable for a compatible AC15 version using a fixed 8 Ω output when the P-TVO15 assignment, mounting, lead routing and feedback phase correspond to the particular amplifier.