PP3/250 PX4 Sound Sales Parmeko Amplifier 1934 Working!

You are looking at a very rare 1934 designed and made Push-Pull Triode output Valve amplifier. Condition is as seen in the pictures. What you see is what you will get...

The original design was published as a High Quality amplifier for the "WM" Wireless Magazine Radiogram.

It uses 2x MAZDA AC/HL triodes which feed a Ferranti AF5C intervalve transformer which drives 2x MAZDA PP3/250 Triodes into a Ferranti OPM6 (C) output transformer into two sets of speaker terminals.

The power supply consists of a Sound Sales type CW 2.5 Heavilly shrouded, excessively large mains transformer. A MAZDA UU3 rectifier is used in combination with two large Parmeko chokes and various electrolytic capacitors exactly to the original specification. This particular amplifier benefits from the original constructor installing an extra element of care for his valves, in as much that a MAZDA DLS1 thermal delay switch in incorperated into the HT circuit to delay the apllication of HT to the output valves until they have reached full heater temperature. This can be seen in operation in one of the pictures.

Only the very highest of quality original components were used and the amp has survived because of this in near totally original condition.

I have tested all of the valves on an AVO VCM and they all have good emmission (85% or above) without any electrode shorts etc.

Test results for the two PP3/250's are as follows: Va=300 Vg=-37 (1) Ia=42 mA gm=4.9   (2) Ia=40mA gm=4.8 both valves have perfect filaments.

The Amplifier has been connected to the mains via a variac and brought up to full mains voltage carefully over a few hours (delay switch shorted out to reform the electrolytics) and it does actually work. In fact it sounds excellent with plenty of volume and a strong bass response with little background hum.

It comes complete with original paperwork as pictured.

This amp may benefit from having all of the capacitors restored, but I will leave that up to the next owner.

No Guarantees are implied or given as this amplifier is now 77 years old, so it is SOLD AS SEEN.

The amplifier will be EXTREMELY well packed, with all valves packed up individually for shipping. Collection in person is also possible, in which case you can hear it working when you collect it.

Don't miss this opportunity to own a rare example of English early Amplifier design.

Item will be posted within 7 days of closing bid.

P & P within the UK is estimated at £30 - £40 (a small charge for packing materials will be included as this MUST be packed excessively well)

International buyers - ask for price first PLEASE (we estimate this to be in the region of £150 - £180 as a guide, but until packed and weighed we will not know exactly)

Payment by PayPal only or cash on collection within 7 days of auction end, other wise the item will be re-listed and Ebay non payment reported.