Trying to guess thge secret of Rudy Van Gelder while he was creating those classic jazz records, the room canceling mic

At your risk. The CD Blue Train - John Coltrain by the label Blue Note was bought from Monastiraki in Athens. It was played on the Pleiades refference playback system with the 1 transistor per channel 2N3053 power amplifier. Sennheiser hD580 Headphones were also used. It sounded very dry which is a good thing as you cannot hear the recording room and therefore the instruments appear to be played in your listening playback room. Drums sounded to the right side. The impression was that a single mic was used for drums and that this single channel was paned a bit to the right by the mixing desk. The drums were bright and there was no low end emphasis at all. Anyway the impression was that each instrument had its microphone. On headphones it can be felt that when a solo is coming the corresponding channel is faded in. This creates a stereophonic effect for say drums as now there is drums leaking to another mic panned say a bit to the left. But how is this recording so dry? Could it be that Rudy Van gelder u8sed the trick of Lou Burroughs (Electrovoice, descibed in the book Microphones) of the noise canceling microphone? Noise means something you do not want to hear, in this case the room. Could it be that there was a microphone, (omnidirectional?) deliberately connected out of phase in order to cancel the room sound. It could even be a mic used for another instument. It does not matter if it is out of phase the double bass for example would be captured correctly as it is close to its mic. The drums would be captured correctly as they are close to the in phase mic. But this mic would capture ambience. So the out of phase double bass mic. But since one of the mics is out of phase the ambience would cancel when mics are added. Its frequency response would depend on the separation of the 2 mics. Since wavelength increases with lowering of frequency if the mics are quite apart only low frequency ambience is decreased which agrees with the fact that the drums sound so dry at low frequency and the low end is at low volume. Anyway this is a guess. Promissing result was yesteday at Pleiades lab when a 2 female XLR to one male XLR cable made long ago was tried with 2 Electrovoice 635a omni moving coil mics. This cabnle allows them to be connected in parallel, but one female XLR is deliberately connected out of phase. The output side of said cable was connected to Sony TC-D5 Pro in mono mode, monitoring through Sennheiser HD580 geadphones. It was stricking how ouside noise and the room was canceled when the second mic was connected but singing just to one of them. Then one of the mics was fairly close to the Pleyel model 9 piano. If just one mic was used the room gave a horrible sound and some notes where so exagerated by apparently modes of the room (reflection of oposite walls), but when the second further mic (the out of phase one) was conneted, these peaks stoped occuring, and the piano sounded much more pro and like a piano.

Creating loudspeakers with enclosures made of linoleum

At your risk. Please take all safety precausions. 3 Ply glued together 9ike plywood) with PVA glue would give 7.5mm thickness. 45 angles could be cut with an Olfa 45 degree cutter to create a good looking enclosure. A circular hole can be made with an Olfa circular cutter. It may be time comsuming to make. But theoreticaly it can be made on a beach. Linoleum has good vibration absorption qualities. This is easy to verify if one hits it outdoors by hand and compare the sound to the ringing of wood. Even by eye it can be see how quickly the flexing vibration is damped. The plylinoleum could be used for making a baffle speaker. If the one drive unit sounds agreesive it can be tamed with someting like 1mH inductor in series. If treble is lacking then a variable resistor can be connected in parallel with said inductor until the loudspeaker sounds similar to reference headpho0nes such as sennheiser HD580.

A very low noise battery powered electron tube microphone booster preamplifier with no capacitors

At your risk. please take all safety precausions. It should be possible with just 1 direct filament double triode DCC90 (3A5) and just 2 signal transformers, like a langenvin circuit. The electron tubes can be operated with grids at space potential which should be even more low noise. So mic connected to input transformer primary, secondary connected to each control grid. Anodes connected to output transformer primary, center tap connected to Vb or (phantom power 48V which may be too much...). Secondary of output transformer is mic out, center tap could be used to get the phantom power voltage. 2 AAA etc 1.2V batteries in series with fuse and switch to supply firect filament cathodes. This circuit has not been built yet so the negative of va (filament supply) possibly connected to negative of Vb and to chassis. XLR pin 1 connected to its nearby chassis terminal too. If phantom power is not used vb can be made from a few 4LR44 connected in series each pair making roughly one AA battery 9see previous posts). The circuit may even barely operate withy 12v, better with 24V, 36V may start being too much as grids are at space potential and there would be field penetration to grids from the positive anode. This kind of circuit has alreadyt being tried a long time ago with an ECC82 (12AU7) both heater and anodes (plates) supplied with 12V through a protective fuse. It worked but it was very sensitive to light as photons apparently created photoemmision and changed the potential of the grids?. If memery is correct gain would increase with brighter light! The DCC90 would consume much less enery per unit time.

An amazing book featuring EMI Columbia Athens

By Stelios Giannakopoulos who was one of the main sound engineers at EMI Columbia Athens studios. It is his biography but there are so many desxcriptions, references and photos. Stelios even get all the way to london CRL. EMI Central Research Laboratories where Alan Blumlein had been inventing to find more unpublished material, photos, contracts etc. The book is currently only in Hellenic language. There are descriptios of the 3 studios. The title is: O Hxoplasths Stelios Giannakopoulos - Stelios Giannakopoulos, Nikos Pathniwths

Decca EsS/4 speaker mod with Decca ribbon horn loaded tweeter

At your risk. Unfortunately or fortunately the front panel had been driled with many holes where many other fullrange speaker had been mounted in the past, and the back cover removed. It was decided to repare the 10in Celestion woofer and Yiannis did a peferct job with a very complient surround. the bass is so deep it is breathtaking. An inductor of 1.7mh is now connected in series with it and a 1uf to 2.2uF capacitor in series with the large Decca ribbon horn loaded tweeter giver by Mark in London near 2000 AD. The tweeter is mounted on top of the carefully gomme laq revarnish job done before 2000. The tweeter can be moved towards the back until bass source and high sorces are alligned. This is best? done by ear while listening to Lady Lady Lady - Georgio Moroder or Barry Gibd pads or strings on What kind of Fool song with barbara Streisand. It sounds close to Sennheiser HD580 driven from the Pleiades 2n3053 single ended single transistor no negative feedback power amplifier.

A mod for the Roberts RFM3 radio

At your risk. It is adding a series inductor with speaker in order to remover mid and high frequency heaviness. It may be for example 34mH and then 107 Ohm in parallel with said inductor to bring back the high frequency sparckle. Many choices are possible, it can be found by trial and error with an inductor and a resistance box.

A speaker crossover network with just an inductor L

At your risk. This idea came by reading Elements of Sound Recording - Frayne, Wolfe. There is a crossover network with the C in parallel withh woofer, L in parallel with tweeter and the 2 drive units are in series. So what if we remove the capacitor. It works! Only the tweeter has an inductor in parallel to it. But it is very tricky as one might need a higher L for the woofer and lower L for the tweeter. Maybe using a tapped inductor, ie an autotransformer could solve the problem, not tried yet. Anyway it sounded quite good with a Philips woofer and a japanese paper tweeter. Actualy it was the first time it was realised that the song What kind of Fool - Streisand, Gibb begins with his (Barry) and her (Barbara) breath in sequence. So far in my humble opinion an 1.7mH inductor in series with woofer and 500nf in series with say 20ohms in with tweeter sound closer to Sennheiser HD580m reference headphones. Driving amplifier is Pleiades 2N3053 with just one transistor in class A of cource and no negative feedback.