See also the OMD Documentary:
Sunday, July 20, 2025
Update to Pleiades 3 DC90 RIAA electron tube battery powered moving magnet cartridge preamplifier for vinyl records
At your risk.
Va is 1.3V, Vb is 48V.
One channel has been built so far with Wago connectors.
It works and sounds very nice.
Signal path:
Africa - Toto - Sony CD Walkman line out - Lipshitz inverse RIAA network - Pleiades 3 DC90 - Sennheiser HD580
It consists for an input transformer, 1 DC90 with grid at space potential (only a capacitor is connected to control grid), 1 DC90 with 10MOhm grid leak bias, 1 DC90 with 1MOhm grid leak bias, and the output transformer. Signal transformers are Sowter ones on octal bases.
As there is no chassis it picks up RF and FM radio can be heard!.
So there is some hiss which should almost be gone when it is built on a Hammond diecast aluminum enclosure.
A rough preliminary frequency response test with anti RIAA (inverse RIAA Lipshitz) network gave -5dB at 20Hz and 20KHz.
Wednesday, July 9, 2025
How Frank Sinatra managed to record in 30th street church studio
Sound engineer Frank Laico narates his discussion with producer Don Costa:
There should be OR not AND on the All Rights Reserved notice of sound carriers
For example, below the second sentence is possible correct as the logic operator OR covers all cases. Is the 3rd version the correct?
For example in a room are musicians and somebody asks: "Please come forward those who play flute and piano" 2 musicians only come. If the proposal is: "Please come forward those who play piano or flute", 7 musicians come. Those 2 who play both, those who play the piano only, those who play the flute only.
I was very lucky to learn this by my teacher of Mathematics Babis Pantazatos. He would thoroughly explain the Aristotelian Symbolic Logic, logic, operators, truthy tables, set theory. On few books such as the book of BBC producer Alec Nisbet on microphones the OR operator is used.
All rights of the producer and of the owner of the work reproduced reserved. Unauthorised copying, hiring, lending, public performance and broadcasting of this recording prohibited.
All rights of the producer and of the owner of the work reproduced reserved. Unauthorised copying, hiring, lending, public performance or broadcasting of this recording prohibited.
All rights of the producer or of the owner of the work reproduced reserved. Unauthorised copying, hiring, lending, public performance and broadcasting of this recording prohibited.
Updates on the Pleiades 3 DC90 battery powered electron tube RIAA MM or MC vinyl disc reading cartridge preamplifier
At your risk. Take all safety precautions. There may be smoke or fire in case of short circuit until a suitable fuse is used in series with a battery.
Va is 1.3V. A 100mA safety fuse is now used.
Vb is 48V.
1st stage operates with grid at space potential, ie with just a coupling capacitor connected to control grid. 2nd and 3rd stages would not turn on in this way due to the initial transient voltage at turn on from the previous stages. S0 a 10Mohm resistor was connected between grid and ground.
It works and the preamplifier sounds very nice. It is directly feeding the Sennheiser HD580 headphones through the output transformer at a low volume.
It makes sense to use an input transformer even for MM cartridges and and additional input transformer for MC cartridges. So thing to having one transformer inside a ribbon microphone, and then the input transformer of the preamplifier.
Promising results.
There is hiss from the second stage, due possibly from bad electron tube contacts or RF pickup.
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