1750ORF Hammond Übertrager Orange Rocker 30 OT119SL

Hammond 1750ORF – 35 W output transformer for Orange Rocker 30 and OT119SL

The Hammond 1750ORF is a bobbin-wound push-pull output transformer for the Orange Rocker 30. The detailed component drawing states 6.6 kΩ plate-to-plate with secondary connections for 8 and 16 Ω.

Hammond lists OT119SL as the comparison reference. Because the product page and series list instead state 6.0 kΩ, verify the amplifier version and component marking before an original-style replacement.

Suitable applications

• Orange Rocker 30 amplifiers with a matching output-transformer version
• Replacement applications around reference OT119SL
• Push-pull stages requiring a primary load around 6.6 kΩ
• Total loudspeaker loads of 8 or 16 Ω
• Guitar amplifiers in the 35 W transformer class
• New amplifiers following complete load-line and mechanical verification

Technical data

Product type

Push-pull guitar-amplifier output transformer

Model

Hammond 1750ORF

Documented amplifier application

Orange Rocker 30

Hammond comparison reference

OT119SL

Primary impedance in the detailed component drawing

6.6 kΩ plate-to-plate with centre tap

Conflicting product-page and series-list figure

6.0 kΩ plate-to-plate

Secondary impedances

8 and 16 Ω

Transformer power rating

35 W

Amplifier topology

Push pull

Winding type

Bobbin winding

Documented inductance measurement

Approx. 10.3 H for the black-to-white section at 1 kHz, 1 V and open secondary; no separate complete-primary value is stated

Black-to-white primary DC resistance

Approx. 68.39 Ω

White-to-yellow primary DC resistance

Approx. 72.23 Ω

Total primary DC resistance

Approximately 140.62 Ω

Black-to-red secondary DC resistance

Approx. 0.602 Ω across the complete 16 Ω winding

Documented leakage-inductance measurement

Approx. 18.25 mH for the yellow-to-white section at 1 kHz with the secondary short-circuited

Frequency response

70 Hz to 12 kHz, 0/-1 dB referenced to 1 kHz

Distortion

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

Dielectric test

2,500 V RMS

Temperature range

-40 to +105 °C

Lead length

At least approximately 305 mm or 12 inches

Dimensions

Approx. 63.5 × 68.2 × 77.7 mm

Mounting dimensions

Approx. 50.8 × 42.9 mm

Mounting slots

Approx. 5.16 × 9.53 mm

Hammond shipping weight

Approx. 3.18 kg; no separate net component weight is stated

Lead connections

Yellow

First primary connection to one output-valve plate

White

Primary centre tap to B+

Black on the primary side

Second primary connection to the opposite output-valve plate

Black on the secondary side

Secondary common or loudspeaker ground

Brown

8 Ω loudspeaker connection

Red

16 Ω loudspeaker connection

Important wiring note

The transformer has two black leads on different winding sides; identify them by lead bundle, position and continuity rather than colour alone

Selecting 8 or 16 Ω

Use brown for an 8 Ω total load and red for a 16 Ω total load. Black is the common secondary connection.

Insulate the unused tap separately. The two taps are not intended as independently loaded simultaneous loudspeaker outputs.

Interpreting the primary impedance

The detailed drawing states 6.6 kΩ, while the product page and series list state 6.0 kΩ. A new design should use the value confirmed for the actual delivered component.

A service replacement must also check the original OT119SL, output-stage circuit and amplifier feedback. A difference between 6.0 and 6.6 kΩ is not necessarily an absolute incompatibility but must not be concealed.

Safety notes

Lethal plate and signal voltages are present on the primary. Positively identify both black leads before power is applied and install the transformer with complete touch protection.

Questions about selection and use

Which output transformer suits an Orange Rocker 30 using OT119SL?

Hammond 1750ORF is documented for the Orange Rocker 30 and OT119SL comparison reference and provides 8/16 Ω outputs with a 35 W rating.

Which 35 W push-pull output transformer provides approximately 6.6 kΩ with 8 and 16 Ω outputs?

Hammond 1750ORF states 6.6 kΩ plate-to-plate in its detailed component drawing and provides separate secondary connections for 8 and 16 Ω.

Can the Hammond 1750ORF be configured for 8 or 16 Ω?

Yes, the Hammond 1750ORF has a brown 8 Ω tap and a red 16 Ω tap. Use the connection matching the actual total loudspeaker impedance.

Is the Hammond 1750ORF suitable for a newly designed push-pull amplifier?

Yes, the Hammond 1750ORF can be used in a new amplifier when the primary impedance of the delivered version, 35 W rating, loudspeaker load, output valves and operating points suit the circuit.