A speaker secret possibly used on Amazon Alexa too

At your risk. A very helpful tip on building or making loudspeakers is that the box be much larger than the drive unit, or vice versa that the drive unit be much smallermuch than the box. This can give excellent no boomy and deep bass if the drive unit has a low reasonant frequency. For a closed box this reasonant frequency needs to be much lower than needed since when when the drive unit is mounted in the box the frequency will be raised by acoustic suspension. Anyway a 4.5in Fostex FE127E gives amazing bass on a bigger Pioneer box (see previous posts). And this Christmass present from my brother and his wife to our parents is an Alaxa, Amazon. Inside it is a tiny speaker. But the bass is surprisingly deep for Alexa's size. Do they also EQ?

Listening tests on a 1m by 1m 2 ply linoleum baffle.

At your risk. Baffle speaker is hung from ceiling from 2 poits using Picture Hanging Systems. A Grundig paper oval 5in by 10in, 5 ohms speaker is assymetrically mounted. It looks rather ugly. 2 ply linoleum glued by PVA is still soft, compliant. But this is peshaps why it absorbs vibration well. Sound is very clear, real and lively. It has this truthful quality of Hf heard near a record player stulys, although listening tests are done with CD. Speaker gives excess of mid and treble. So an inductor of say 0.7H is connected in series. A resistor (starting as a variable resistor) in parallel to inductor may be needed. Bass is nice. It could have been better as there seems to be a mid bass reasonance, (due to drive unit?). Would bass be more deep if more ply linoleum was used, but it would be very heavy. Perhaps using a say 50cm by 50cm would be more appropreate as on the Zeis Ikon baffle cabiet speaker. Barbara Streisand sounded very nice with speaker driven by the Pleiades single transistor 2N3053 power amplifier. Test is mono, actually only one cD channel is used. Since around New Year it had been desided to have only the Great Celestion Ditton 150 speakers in the small Pleiades control room. All other speaker tests are done on the much greater size living room. Still the Rola Celestion Ditton 150 speakers (in stereo) driven by 2 Pleiades 2N3053 power amplifiers in pure class A are prefared and this is the refference Pleiades reproducing setup. Aknowledgment to Mr. Yiannis for those beautiful souding speakers with so deep bass, fluid mid and extended balanced high frequency content. The amplifiers have small output transformers (see previous posts, after all power of amps is much less than 1 Watt. With the big Sowtewr SK05s output transformers although they are exxcellent and more efficient, bass on this particular setup may be much.

Brushing teeth with sea water

At your risk. This is not a medical advice. Just personal experience. Using now for a few years very good quality toothbrush Curaprox and Jordan. Firstly Curaprox is used, then Jordan which seems to be more helpful for inbetween teeth gaps. Using no toothpaste. Brushing after everymeal. Teeth are in quite good condition. When sea water was replaced by tap or filtered water, it was a disaster. Sea water seems to kill harmful microrganisms. This is possiblyt done by salt dyhydrating microbe cell membranes by ormosis. After brushing teeth, both toothbruses are rinsed in plenty of sea water. At your risk.

Happy New Year

Ευτυχισμενο Νεο Ετος

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.