Resonance Circuits and Resonance Systems

[Belfior]

Well, several things come to mind. First, you probably don't have enough turns to get a reasonable electrical length for your secondary coil, which means that the resonant frequency may be so high that the transistor and other circuit elements can't keep up. This system will work best with a resonant frequency under 1.5 MHz.  Second, your primary is mounted too low. It should not be below the bottom winding of the secondary; it should be maybe 1/4 to 1/2 inch above the bottom winding.
Third, are you quite sure you have the 2n3055 connected properly, with the Base and Emitter leads properly oriented, and a good solid connection to the Case (Collector)?

The first thing I would suggest is to make another secondary coil using #24 or smaller magnet wire and at least 400 turns on a former of the diameter you are using. Second thing is to mount your 4-turn primary just barely above the bottom turns of the secondary, not below it. Third thing is to carefully verify the connections to the transistor. Don't use clipleads or other long wire lengths to connect your components!

If you can find an old big CRT television that someone is discarding, you can get magnet wire from the degaussing coil that is wrapped around the screen end of the picture tube. Also from the yoke coils, but this is more difficult to strip cleanly off the yoke.

I remade the circuit. Got a 220R resistor in series with the pot, so the resistance won't go to 0 ever. I am rewinding the coil with 0,5mm wire and 800 turns. Bought 2 IKEA salad bowls for the top load. Shitload of stuff arrived from China, so I might try to fire this up in a few days after I take inventory. It takes sometimes 2 months for stuff to arrive so I gotta figure out why I ordered some of this shit...

[Magluvin]

I know an engineer who worked in the Norwegian speaker factory SEAS, one of the world leading manufacturer in high quality speaker parts. See www.seas.no for more information.
The efficiency in % is an expression that depends on temperature, pressure, humidity - the mass of the air at a given standarized form.


I have no formula, but the efficiency was once expressed in both SPL and %. I am quite sure you can google the mechanical transfer function between a moving diaphragm/membrane, and the surrounding air. Shorter the distance to the speaker will increase the mechanical efficiency.


The mechanical efficiency of the speaker driver itself is much higher, but still quite low. It depends on loss in suspension, resistance in the voicecoil, flux density through the coil, moving mass.


Vidar

Hey Vidar

I had worked with a couple guys back when I was just getting more into sound quality. They had a shop across the way from mine. They were home speaker developers. They would develop several different sets each year and take them to a trade show, ces in vegas, to promote their products. They were very set in their ways. They believed in point source, strictly just a left an right on stands and no subwoofer needed. Odd thing was their ideal car setups compared to tried and true tested ideals of my time, at the time. They would set the tweeters in the rear deck and mids in the front. They demoed it for me and i didnt 'see' it. No matter what they did with the adjustments or moving the tweeters, I did not experience the stage in their car, but I did with their home speaker models. And they did not give me daps on my kick panel speakers in large enough kick enclosures ported to 60hz, of which did produce a stage you could see and feel out over the hood of the car(88 grand prix). The ported tuning enabled me to crossover high pass at 80hz, but it still played flat just below 60hz, without having to expend a lot of power below 80hz. Then My sub, 15in in 3cuft tuned to 27hz ported was sealed to the frame behind the rear seat with 2 4in ports up into the rear deck. No trunk rattle, as Tk mentioned he detested.  After about a week they wanted to hear my car again with some of their test cd's and they finally caved and liked it a lot.

The big problem in the car is the difference in distance from all the drivers, especially from left to right. Some try to correct it by putting the front stage up on the dash, but the glass causes more issues than a dual 32ch eq can solve. Even time alignment only helps with optimum placement and 'angles' of the drivers. First is to get the fr mid and tweet (kept close together)as far forward as possible to help minimize L and R distance differences, and to work an angle where the right is aimed toward the drivers head and the left to the pass head and work in that zone to get the best you can. On axis is the loudest and more off axis less loud. So this helps balance L and R perceived loudness, then some tilt upward can what I call throw the staging up over the dash. Im an only front speakers and sub kinda guy. Too many speakers screws it all up. In some cases where the install doesnt have the possibility of building good kick panels and the front speakers are lower than Id like, Ill put in some rears with no tweets and just bring up the gain till the front stage comes up but you cant detect the rears.  Been in it seriously for 25years.

Back to the eff. 

Yeah I get that at 1m away the comparison to the input has diminished. So lets say we were to measure it at 1in, or closer if need be, are we still super inefficient? The 1m spec is relative to that distance. I want to get down to the nitty grittty of what is the actual eff of the speaker. The 1m spec, just because it lost so much over the 1m distance is still directly related to the actual ouput of the cone. So I think the 1% is a bit misleading to say as you have as to the actual in vs out of the speaker. If the speaker were actually 99% eff, its not fair to describe it as even 50%eff let alone 1%. What ever a 100% ideal speaker produces at 1m is still a good number for affecting the air at that distance. 100% eff speaker should be able to produce a particular db level at 1m every time. So that 1m number is what Im looking for to be able to see the actual eff of known drivers out there.

In all this as I have explained earlier Id like to translate all this to an electronic circuit that the first aim would be initial eff then adding resonance to increase that efficiency. As i said earlier, if the sub were in an infinite baffle, the actual raw in and out is what it is, just the way it is. When we go vent tuned, we get a boost out vs in. Then when we go dual chamber tuned to the intended low tuning freq and also rings an octave up, those 2 complement each other and increase the gain for each. One of the designs has just an alternate ported chamber within the enclosure. I need to build it to see what goes on there and understand it more.


Ill look more for the answer. Thanks for the info

Mags

[Low-Q]

Mag,


Have in mind that a resonance system is depended on its Q-value. This value is very hign on systems with long lasting sustain. When you load the system, this value drops like a rock.
An ideal system have 180° phase offset between current and voltage. A resistive system has 0° offset.
The system will be between 0° and 180°, and never as much as 180°.


Vidar

[tysb3]

Make A Vortex Cannon!
https://www.youtube.com/watch?v=30yK6Qf4dZA

[Magluvin]

Make A Vortex Cannon!
https://www.youtube.com/watch?v=30yK6Qf4dZA

In the 70s there was a toy gun that had a big funnel with the small end as the spout and a pull back to load lever on the top. Just looked on ebay and they show some but not the exact same. This funnel had like a 2in fr spout and the funnel was a smooth curve arc from the big side to the fr spout. You can feel the air ball hit you just like the vid shows. Neat stuff.

Mags