HRSASA build a valve amplifier competition

Started by VK5ZFZ, Aug 20, 2023, 05:59 PM

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HRSASA Valve amplifier competition 2023

The aim of this competition is to foster community interest in the 100th. Anniversary of broadcasting in South Australia, home construction of valve HI-FI amplifiers, and awareness of the Historical Radio Society of Australia South Australian branch and its activities.

 The competition is open to any South Australian resident, who has constructed his own amplifier, or one made by a relative who is or was a South Australian resident.
There are a number of different categories each of which will have a number of rounds to find both the Judging panel and the listener awards.  The judging panel awards will be based on technical as well as sonic character to find the winners, the listener awards purely based on their preference of sonics.

Preprinted score cards will be made available to all registered listeners/voters and the judging panel.

Depending on the number of entries there may be more than one round for each category eventually ending up with the top 3 amplifiers for placement as first second and third place in each category and grand overall winners.
The HRSASA reserved the right to publish all findings and entrant's circuit diagrams over the 12 months following the competition. 

Each entry will be by way of the prescribed entry form, those of the public and HRSA members who would like to join the listener audience and judging panel will be required to make an online booking for audience seats on testing days.

Adelaide radio station involvement both commercial and non-commercial to promote and be involved with the activities will be most welcome.

The judging panel will arrange for 5 x 2-minute test grabs of music as a standard reference, the same set of speakers and program source will used for every amplifier under test. The nominal speaker impedance will be 8 ohms. The program source will be +8dbm balanced line 600 ohms. Adapters and attenuators will be provided to accommodate 500mv p-p input and unbalanced amplifiers.

Judged panel prizes will be awarded for each category winner for first, second, and third place (18 awards). With a Judges award to the best overall amplifier (one award), and Judges best technical achievement (one award).  The listener award will be for first place in each category (6 awards), and best overall amplifier (one award)
Cost of entry is free to all HRSASA and VK5 club members and the public.

1)   Single Ended
2)   less than 17 watts push pull
3)   OTL amplifier
4)   Hybrid amplifier
5)   More than 17 watts Push pull
6)   Open section any amplifier (including solid state)

1)   All entries may be either mono or stereo, those with an internal preamp with equalization will need to be tested in the flat EQ position.
2)   All amplifiers must be entirely valve designs (solid state rectifiers permitted) there will be two additional categories hybrid and fully solid state (Open) to accommodate other designs.
3)   All entries must be the applicants own work or that of a relative i.e., Grandfather or Fathers construction and must be a SA resident.
4)   Modified or commercially built equipment is not permitted.
5)   Each submitted amplifier should include a schematic diagram (hand drawn is OK) and a paragraph about any "Clever or novel" aspects to its design or construction.
6)   Credit will be given to other information supplied such as photo's taken during construction, test results, notes on what worked or failed during the process.
7)   An amplifier can only be submitted in one category, entries by judging panel members may be judged but no prizes awarded.

Prizes donated by ROLA Australia
Best overall amplifier based on sonics    one pair of ROLA OPT-50 ultralinear push pull output transformers valued at $800

Best technical achievement based on construction and circuit design
one pair of ROLA OPT-15 ultralinear push pull output transformers valued at $400

Listener award best overall amplifier based on sonics
one pair of ROLA OPT-10SE single ended output transformers valued at $140

All other awards a certificate of achievement


Looks like a very interesting competition Graham!  Thanks for you input!
John  (VK5RJ)
AHARS President