Description
Condition: Grade A — Excellent
This unit presents in mint condition, consistent with being boxed and likely unused or near-unused throughout its life. Please refer to our photographs for a full assessment of cosmetic condition.
The Delta 30’s internal construction reflects Leak’s established engineering philosophy. The amplifier is built around four plug-in printed circuit boards — two preamplifier boards and two power amplifier boards, one of each per channel — which slot into a main motherboard on the chassis. This modular approach was a deliberate design choice, simplifying servicing and allowing individual stages to be inspected or replaced independently. The power transistors and temperature compensation diodes are mounted on a separate heatsink, insulated from the chassis by mica washers, while the transformer and main power supply components are chassis-mounted. The preamplifier boards carry the RIAA equalisation circuitry for the disc inputs, tone control components, filter circuitry, and appropriate amplification for all inputs.
The input complement is thorough for its period. There are two disc inputs — Disc 1 with RIAA equalisation for moving magnet cartridges at 2mV sensitivity, and Disc 2 with selectable sensitivity, both with high/low impedance switching on the rear panel. Tuner inputs are provided via both RCA phono sockets (with a microphone option on Tuner 1) and a DIN socket for tape record and replay. A tape monitor loop allows connection of a tape machine for both recording and playback. Speaker output is via a pair of 2-pin DIN connectors. Front panel controls include bass, treble, balance, and volume, with push buttons for mono (left and right source options), tape monitoring, a high-frequency filter, and speaker selection. A headphone socket is provided on the front panel.
Rated at 15 watts per channel into 8 ohms continuous, the Delta 30’s power output is modest by contemporary standards, though the IHF music power figure of 40 watts into 8 ohms gives a more realistic sense of its dynamic capability. The damping factor of 20 is adequate for the period, and the total harmonic distortion figure of 0.1% at all power levels up to 10 watts is creditable. The amplifier is well suited to speakers of average or above-average sensitivity.
Important Owner’s Notes
Despite its cosmetic condition, prospective buyers should be aware that this amplifier is now over 50 years old and its internal electrolytic capacitors are original. The minimal usage of the unit does not change this: electrolytic capacitors age through time regardless of use, and a precautionary service — including replacement of the main electrolytic capacitors — is recommended before extended use. This is routine maintenance for any amplifier of this age and should not be viewed as a reflection on the unit’s current working condition, which has been confirmed by Andrew. The plug-in board construction makes servicing by a competent technician straightforward. We would be happy to discuss this further prior to purchase.
Technical Specifications
- Type: Stereo Integrated Amplifier
- Power Output: 15W + 15W (8Ω, continuous); 20W + 20W (4Ω)
- Music Power Output (IHF): 40W into 8Ω; 60W into 4Ω
- Total Harmonic Distortion: 0.1% at all power levels up to 10W at 1kHz into 8Ω
- Total Intermodulation Distortion: Less than 0.2% at all levels up to 15W into 8Ω
- Frequency Response: 30Hz – 20kHz (±1dB)
- Signal-to-Noise Ratio: 63dB below 30W into 8Ω (Tuner/Replay inputs)
- Damping Factor: 20 at 1kHz into 8Ω
- Channel Separation: –50dB up to 1kHz; –30dB at 10kHz
- Input Sensitivity — Disc 1 (RIAA): 2mV / 47kΩ
- Input Sensitivity — Disc 2 (RIAA): 10mV or 30mV / 33kΩ or 100kΩ (switchable)
- Input Sensitivity — Tuner 1/Mic: 25mV or 2mV / 47kΩ (switchable)
- Input Sensitivity — Tuner 2: 60mV or 250mV / 50kΩ (switchable)
- Input Sensitivity — Replay: 400mV / 47kΩ
- Tone Control Range: ±16dB at 50Hz and 14kHz
- Filter: 12dB per octave roll-off above 6kHz
- Dimensions (W×H×D): 344 × 119 × 254 mm
- Years of Production: 1972–1974
- Country of Origin: England, UK
Why Buy From Us
With over 40 years of experience in the Hi-Fi industry, we are well placed to assess and test equipment of this type. Every item we list is fully inspected and tested before sale — this unit was checked by Andrew in our workshop.
When you buy from us you can expect:
- Full inspection and testing prior to listing — not simply a visual check
- A 3-month guarantee on every item we sell
- Transparent descriptions with no omissions
- Professional packaging to ensure safe delivery
- After-sales support available by phone or email should you have any questions
The Leak Delta 30 is a rare find in this condition — boxed, and near mint condition from the early 1970s are seldom encountered. It represents an accessible entry point into classic British amplifier design from a name with genuine pedigree, and its modular construction makes it well suited to long-term ownership. A precautionary capacitor service is recommended before extended use given its age, but the unit is presently working correctly and presented in quite remarkable cosmetic condition. This is a single-unit listing, inclusive of the original box. Please feel free to get in touch with any questions prior to purchase.
