Listening to Guilty - Barabara streisand, Barry Gibb CD on the Pleiades 2n3053 single transistor per channel power amplifier in class A with no feedback

At your risk. Today Eleni from the excellent Record shop Record House handed me the anticipated CD. The amplifier is in more detail described on older posts. The output transformers are the hand made ones wound on small Siemens ferrite E inverted E cores with air gap added. Frequency respone which number of turns described on previous posts is flat 40hz to 40KHz with no negative feedback of cource. The sound quality is amazing. Breathtaking, promising. deep but not boomy bass, smooth mid and amazing extended treble whith no harshness, with sweetness and cymbals appearing to be real ones inside the room. Barbara and Barry in breath taking peformance. Signal path, cD - Sony CD Walkan line out - Pleiades 2N3053 2 channels - Celestion Ditton 150 at 2 m in a small bedroo with 3 differenct size panel low frequency absorbers. The big panel is behing the speakers away from the wall, its upper side only touching it and its lower side touching the wooden floor. panel in landscape orientation. Panels made of drawing frames with canvas with betumin roofing felt panel fed at the back side of them. Linoleum must be more suitable for enviromntal and cleaner air of room condition.

Increqsing the gain of the Pleiades 2 K117 microphone preamplifier

At your risk.It is a 2 JFET microphone preamplifier, mic feeding the input transformer and 2nd JFet feeding the output transformer which feeds for example the Sennheiser Hd580 headphones. Vb has been changed to a 9 Volt battery. Load resistor of first stage has been changed to 100Kohm, and of 2nd stage to 22Kohm. Now gain is very high and the 2nd stage clips. There is again FM radio reception, floating wire picking up RF etc. Maby a potentiometer should be connected between the 2 stages to attenuate what the 2nd JFET gets from the 1st. Also to check if the whole thing does not oscillate.

Shure SM7 internal switchable filters

By looking at the datasheet of the SM7 it makes sense that when the single 240mH inductor is connected, there is low cut. And when the other filter of 11mH in series with 220nF is connected the high frequency response is flat. When no filter is connected the capsule, similaer to SM57, or SM58 manifests its presence peak that the inventor Ernie Seeler did not like. Would an SM58 sound very similar to SM7 if similar band arrenuate filter is used, and similar high pass filter is used?. Attention should be made to the fact that the impedance of the SM7 is 150 ohms whereas of the SM58 is 300ohms or perhaps more. Also one must take into account that rea; inductors have series resistance which is a good thing for example making the slope of the hi pass gentler, and the Q of the resonant filter lower increasing the bandwidth of the band reject filter and arranging the maximum reduction of the peak to be such that a flat frequency responce is obtained. Would it be possible to use variable series resistors for that purpose? The SM7 seems to be a very good microphone if Michael Jackson, Whitney Houston were cutting vocals in the studio with it.

There are mistakes on the constant k, T, PI filters which are now corrected on the previous posts

At your risk. Please also note that these filters have by definition the useful property that ZL times ZC equals R times R for any frequency. (the impedance of an inductance L is 2 times PI time L, the impedance of a capacitance C is 1 over (2 times Pi times C). It would be interesting to use as image impedance the output impedance of a Shure SM58, eg R+320 ohms and calculate suitable imductors, capacitors for various high pass cut of frequencies, or even a band reject filter of say 5Khz to convert the peak to flat as is done of the SM7 microphone?

An amazing book on perfecting eyesight without glasses

At your risk. It is fascinating , The Bates method for BETTER EYESIGHT WITHOUT GLASSES - W. H. Bates, MD A very inteligent doctor. shakes older theories like Einstein did. In fact the most recent Pleiades filter of 155mH was assembled without using a magnifying glass. Winding was done months ago using a magnifying glass. Diameter of wire is 0.08mm. Number of turnes 261. Siemens Epcos toroid assembled inside Neutrik modules to create a nice looking XLR female to male inline filter. It sounds nice at 24in from mic, mic above head towards nose.

An attempt to remove excess mid high frequency content from SM58

At your risk. Trying to figure out how the beautiful vocal sound of Lady Lady - Morroder may be made. Mic distance used on this experiment is 24in, 30 degrees towards nose above head. A Pleiades inline low cut filter of 155mH was connected to mic. Then to reduce mids a filter like the one inside SM7 was made with 11mH, 220uF in serries and the total connected again across source. In fact mic initialy was not connected, the line out of Sony CD walkman was connected having an output impedance of 300Ohms on a vocal recording that was not good, too mid heavy. Then the Pleiades 2n3053 power amp was driving the Celestion Ditton 150 speaker. The filter worked and by using a capacitor box 100nF was found to sound more proffesional than 220nF on this particular male vocal case. If wa calculates the resonance frequency by equating the inductor reactance to capacitor reactance ie wL=1/wC, where w(omega) is angular frequency or velocity of the rotating vector that produces a sinewave on its projection to the sin axis of a trigonometric circle, w=2 times PI=3.14 times frequency. A trigonomatric circle is defined a circle with radius 1. For C=220nf we get rougghly 3.5KHz, for C=100nF we get roughly 5KHz which seems consistent with the inherent peak of SM58 that i wish to reduce in hope that the higher frequencies would shine even better. A resistor in series might be needed too to adjust the notch filter bandwidth. Initial listening tests with SM58 at very low volume are promising. Low volume with just 2 JFets driving the HD580 headphones (Pleiades 2 K117) pre amplifier directly driven from mic trough a Canford inline input transformer. All filters connected just after mic, before the input transformer.

Equations for constant k high pass filters

At your risk. They are given on previous post with title: Shure SM58 connected to Pleiades (175mH:175mH) or EMI RS106A part 2 An important term is image impedance, see references on previous post. According to the book:Elements of Sound Recording - Frayne, Wolfe the T network should be 2C capacitor on left side, inductor L to ground, capacitor 2C on the right side. Network Pi should be on left side inductor L/2 to ground, Capacitor C on top sending music signal to the right inductor L/2 whose bottom side is connected to ground.