Signal path of previous Pleiades 2N3053 in stereo post

Signal Path:The Alan Parsons Project The Definitive Collection CD - Sony CD Walkman D-EJ758CK 300 Ohms line out - 2 monoblock Pleiades 2N3053 - 2 (hand made) KEF CS-5 constructor series speakers with tweeter minus terminal connected to minus of speaker terminal - 1.7m x 3.2m listening room with all 3 doors open, back of speakers facing the double door, total area of lab about 100 meters squared, loudspeakers separated by 1m, on top of different cushioned chairs with springs, listener distance 1.4m. Power consumption must be just a total of 20mA at 24V. Sound quality: Hard to stop listening, If I could change your mind track sounds into cliping and too loud, much else like velvet, deep, easy, HF extended with creamy midrange and deep sound stage, sometimes too loud after a few hours I got tired, volume control should be reduced. Left, right spakers now corrected. Listening to Alan Parsons Sound Check 2 CD, more lifelike than commercial recordings. It is somehow hard to detect distortion with this amp even if it might be clipping, as the non linearity knee seems very gentle, so distortion of low order as it is just a single stage amp with almost no feedback, just a bit local from C to B. Still do not know at such level of sound quality if i prefare mono to stereo. Mono is better if one listens to the difuse sound field in other rooms. This 1920's topology implemented with a small transistor may be miraculous. Commercial recordings may sound too good to be natural. On the other hand for example the pipe organ on the AP CD sounds like being in an English church with the great long reverberation surrounding us. Pedal bass D does not sound creating intermodulation with upper parts of harmony. The train can burst you into laughter especially the squiking brakes.

The 1st listening test of the Pleiades 2N3053 single transistor power amplifier in stereo

At your risk. The design of such a system had been aided by listening in mono for many years until it souded almost perfect. How about now in stereo? Pleiades 2N3053 schematic description for each channel: 24V from 2 lead acid 1.2Ah batteries in series, + terminal to fuse holder with a 100mA fuse to one wire of primary of Sowter SK05s output transformer, other primary wire to the Collector of the 2N3053 transistor, either RCA/GE or Motorola, Emitter connected to battery -ve and signal ground, class A bias resistor 100Kohm to 200Kohm from Collector to Base using a series combination of fixed 100KOhm and 100KOhm variable resistor, music signal feeding the Base through a 10KOhm variable resistor (rheostat ie using only center and another terminal of a 10KOhm potentiometer), music electromagnetic signal output to all its pristine glory from the 8 Ohm secondary of this fabulous Sowter output transformer. This 1920's topology implemented with a small transistor may be miraculous. Commercial recordings may sound too good to be natural. On the other hand for example the pipe organ on the Alan Parsons Sound Check 2 CD sounds like being in an English church with the great long reverberation surrounding us. Pedal bass D does not sound creating intermodulation with upper parts of harmony. The train can burst you into laughter especially the squiking brakes.

Increasing the power of Pleiades 2N3053 amplifier

At you risk. Increased Vb from 12V to 24V, quiescent current with 200KOhms bias resistor from collector to base is about 10mA. Amazing sound while power is still much less than 1 Watt. On 1st May a second amp (the other channel for stereo) was built on 47cmx31cm plywood base board below an orange 40cm x 30cm linoleum Tarkett Etrusco sheet, connections with Wago connectors, pin wirewrap strips for transistor base, potentiometers, RCA connectors etc, connected with wirewrap, ie no soldering iron used troughout!. Fuse in series with battery is 100mA. Amazing sound with KEF CS5 or Celestion Ditton 150 speaker, both channels not tried yet. Naim Nait 2 amplifier tried on one speaker too for comparison, much louder but less bass depth or extenssion, bass sounded extended only when Nait was on stereo driving a pair of speakers. The 2N3053 almost no feedback design sounds easy with delicate, easy , extended treble, airy, quicy midrange and deep bass since the output transformer was included. Photographer Vangelis is interested in building one from the Pleiades 2N3053 schematic drawn to him. Vangelis kindly donated a pair of F&K Design speaker bases. Thank you God listening on yesterday's prayer.

Doubling the loudness of the Pleiades 2N3053 single transistor minimum negative feedback audio power amplifier

Audio transformers are amazing sounding fantastic creatures. Collector to base single biasing resistor changed from 100KOhms to 200KOhms. Sound is much more open, bigger, deep with more detail, louder. Collector current is just 5mA, am I dreaming? It makes sense since supply voltage is 12V, therefore Vb:Ic=12V:5mA=2.4KOhms, the output transformer is 2.5KOhm to 8 Ohms so impedance is matched, hence no energy reflected back from the speaker to the transistor. Signal path: Time - Alan Parsons Project - Sony CD Walkman 300ohms line out - Pleiades 2N3053 with Sowter SK05s - KEF CS5 constructor series (tweeter connected in phase since the day before yesterday!)

On making quick changes on experimental circuits

At your risk. Without using a soldering iron or screw driver for barrier strips or springs or aligator clip cables, the Wago instant snap barrier strips can be used. For example in connecting the Sowter output transformer SK05s to the Pleiades 2N3053 single transistor power amplifier and the speaker, (2.5Kohm to 8 Ohm impedance trnsformation ratio).

Pleiades single 2N3053 class A audio power amplifier with Sowter SK05s output transformer

At your risk. Feel so happy. Rediscovering the merits of larger speakers. Thank you Vicky for pointing out how good single transistor amplifiers sound. When including the output transformer the bass is huge, deep, jaw dropping even at 1/10 of a watt output. Schematic similar to Pleiades 2N3055. Bias with a 95K from collector to base. Signal path: Time - Alan Parsons Project - Sony CD Walkman line out - Pleiades 2N3053 with SK05s output transformer - Marantz Imperial 5G or KEF CS5 or Philips FWB-C155D/00. Operating conditions: Vb=12V , Ic= just 12mA. Smooth dreamy sound.

On opening vintage 80's radios, keyboards without breaking the plastic screw bearings

At your risk. Screw may well be rusty. If high torque is applied on screwdriver the plastic nest will break. But not if the screwdriver tip is heated up at the right temperature so that the plastic becomes soft and no high screwdriver torque is needed. (insprired by a technique Albert is using if needed on some piano screws). This technique successfully used on completely dismantling the SONY Sports CFS-950 yellow, 606152.