Supersonic Conquest radio's PR80 and PR80C

[Mike Watterson]

A regular transformer without the taps can sound the same with a suitable feedback circuit. Those are still available new or NOS. It's a niche fad.

It's fantasy that this exact transformer is needed to "recreate" the sound.

That's great to hear.  Might you have some examples of these regular transformers?  Fad or not....  collectors are going to collect..   Im just here looking for information.

No, they will not be convinced. They are chasing a dream.

Altai / Eagle

LT44 AKA P631M, blue tape, is a driver transformer for push-pull 20:1 ratio.

LT700, red tape, is a push-pull output transformer

The two coils on the primary side consist of 420 turns each. Therefore, there are 840 turns in total with a centre tapping. The total inductance is 550 mH, and DC resistance 63 Ohms.

On the secondary side, the coil consists of 45 turns. The inductance is 2.25 mH, and the DC resistance is 0.38 Ohms

You can design for 3 Ohms or 8 Ohms speaker and silicon (NPN or PNP) or germanium transistors, or even FETs.

Using feedback from the secondary (at the speaker) allows you to simulate the taps. Having a driver stage for the feedback using an LT44/P631M allows easier simulation of the original.

Note this is about 300 mW max.

https://pattern.usefulcomponents.com/listing/1143368797

Loads of companies sell these parts as well as miniature mic transformers by Altai/Eagle, which can be used between an electric guitar pickup and a regular 10K to 100K line input for "colouration".

With push-pull the DC currents cancel, so you can use any centre tapped transformer without an airgap. A mains transformer with two primaries for 110-117 and 220-240 and a 6 to 12V secondary (depending on speaker) can make a 1 W amp to 100W amp depending on pair of valves (ECC82 even at 24V, Russian rod Pentodes, EF80, triode of ECH81 (=ECH83), not just 6V6, EL84 etc). There are also transistors that can work off 100V to 200V HT. A Shaver transformer is a "safe" isolated supply for 130V or 260V nominal up to 20W. Those are current limited, so make the amp soft limit at 5 to 10W.


Obviously for transistors off low voltage you can use two small 5W or 10W transformers back-to-back on the primary and connect transistor collectors to a centre tapped secondary. The 2nd secondary connects to the speaker. Or one transformer with two suitable secondaries. Lots of scope to experiment with feedback signals that have gone through the transformer.

The taps on the original are simply for negative feedback to give a cleaner sound with less distortion (colouration) from the transformer. There has been much nonsense written on the Deacy (Deaky) amp, some in the Wikipedia page. There is nothing clever or magic or special about the original, except in the minds of some people.

It's pointless replicating the the original transformer.