Good advices for a newbie (threading tools lathe)

[C-Bag]

ooooooh, to much fun!!! So many things going on here. Playing with the materials of the horns is very interesting. But like I learned when trying to mix one of our albums it's VERY easy to get lost. My old friend of almost 50yrs who we went through the audio stuff together and he taught me how to play guitar, is now a pro live sound audio engineer. He is in another world to me but he can dumb it down enough for me to understand some concepts.

Several of the major ones is just like you have mentioned many times is crossover points and resonance peaks. And then the real gorilla in the room time alignment. This is why all the pros went to active crossovers years ago. Now they have moved on and everything is computer controlled in the amps and networked into the engineers laptop along with the digital mixers.

Through him I bought an old copy of SMAARTLive, the program the pro's use to analyze the rig. Everything from time align to realtime frequency analysis and a ton of other stuff that makes my head swim. I used it to set the eq on my live PA by hooking it through a mobilepre into my laptop and it would show me the peaks that were causing feedback and I used a 31 band eq to tame the peaks/kill the feedback. Worked ok, but it was a little like using a hammer to kill flys.

Then along came a guy who was looking to sell a dbx DriveRack 260. Amazing piece of kit. Crossover, realtime analyzer, compressor, notch filter, parametric eq, 31 band eq, feedback buster, delay and auto eq, all in one rack space and has a plug to jack directly into the laptop where you can configure and daisy chain all these things any way you want, right on the laptop. Their bottom of the pro line unit. Now obsolete with my new line6 m20D digital mixer.

I mention all of this because, bravo! You are going in the right direction with analysis. But I hope you know you are in for even more complication

My current upgrade dream is to make some new speaker cabs using my spare set off ESS drivers in a 2x10" modified line transmission cab with another Hafler amp for biamp and use the 260 and SMAARTLIVE to tune and align the system.

I too am working with gas welding aluminum. There is a guy here who teaches and sells all the stuff. Not easy or cheap, but very satisfying and another thing I want to have time to do. Love the stuff with your motor cycle....or do I see motorcycle frame with a scooter drive? Always thought that made more sense, lower center of gravity and they certainly have enough HP to get me in trouble.

I'm more low tech these days, in love with my ICE recumbent tadpole trike. My dream is to build a aluminum bodied velomobile...maybe even electric assist. But I have more dreams than I have time left

[PJs]

A lot going on here but I'll try to stay on point with the sound stuff as best I can.

First I believe you are right about the crossover being critical and think that going with an active is the best approach to cover all the variables in the horn design.

Coupling: Personally I think the threaded approach gives Better Coupling because of the continuous contact throughout the threaded length (quality 2A/B or 3A/B threads). With a tapered press or slip fit and (a) set screw(s) you will likely create distortions in the material, effecting the resonance of the cone as well as the direct coupling to the driver. I've never used Loctite products with this type of coupling but would probably try them in moderation to insure they don't come loose from vibration. Heat may be another factor, which the AL will help with.

Sound Mapping: The only way to achieve what you are trying to do IMHO. I have the EMC8000 mic and used it extensively to 3D map the coupling of my transducers to the sound table I designed a few years ago. I used spectral analysis software to capture all the data from the 3D grid map I created to measure everything. Because I was measuring within about 2' of the table the EMC8000 worked fine and is a great mic for those distances. However it is relatively directional like a shotgun mic. A room is another story because of the shape, variable densities of it, and above all the reflectivity of all of that. For speakers it's great!

Horns: I don't have much wherewithal around their design and implementation, but it's still Physics. Marv would be much better suited to help on this than me!

The basic principles of sound transmission are: Frequency, Amplitude, Resonance, Harmonics, and speed of transmission based on the density of the medium. In this case a sound transducer that has all of these characteristics already, which will be coupled to a directional amplifier/modifier (horn)...which is why I was so impressed with your other shop made horns which fit Your Space and Tastes of quality!! To me the key is the shape and density of the material you are coupling to the transducer. Aluminum has a sound transmission speed of 3100-6400m/s depending on the type (density), whether its cast, rolled or extruded, etc. If you apply that to the Lambda(wavelength)=Velocity/frequency formula it will give you some "Basic" starting point for your guide and if you are going in the right direction but won't cover the shape...much more complex. The diameters (ID/OD), will effect the sound coupling and frequency response curves and wall thickness can effect harmonics and ringing. The shape of the internal cone will more control the wave propagation and directionality.

Sound has always been fascinating to me and partly why I built my sound table and HAWK delivery system. Whether it be listening, meditative or healing, I have a Strong Sense that Edgar Cayce was right with his point that "Sound will be the medicine of the Future".

Here is a picture of my HAWKs system. Note in the middle of the rack is an HP, 4 channel signal generation that works from DC to 600Khz and the ART SLA-4 amp at the bottom. The other pic is in our clinic (now closed) and shows the Korg attached...one of many delivery systems including 5.1 Surround headset driven optically.



It's now in storage and may donate it to the VA one of these days...when I'm ready to let go of it.

Thanks Stefano for starting this thread, I'm impressed and intrigued...look forward to what you come up with and how you did it!!

C-Bag, honestly I'm not sure how to answer you question of Excite or Dead, sound will permeate the material at some level and travel the path of least resistance...even a port's edges will vibrate as the sound travels through them. Again I'm a relative novice to some of this you guys are talking about...

Till Then, ~~~> ~PJ

[rendoman]

I'm impressed! I'm lucky to have found some audio fans (and pro) so prepared!
for now i wish you a merry xmas!
i got two short question for curiosity:

- some times ago i see a recumbent bike (sport road type), in your opinion it's so fast compared to a normal cycle?

- i see some really nice electronics for medicine use, what kind of diseases can be approached with sound?

[C-Bag]

I think you are talking about recumbent bicycles, so yes we are once again in different camps I used to have an Italian 10sp bicycle that rode a lot. I always felt like it was a torture machine that I want to go as fast as I could so I could get off the damned thing. My hands and wrists always ached and were a sleep and I couldn't sit down for a week. Now I don't care how fast I go, it's all about enjoying the ride, the day, the trail and being outside in one of the most beautiful places on the planet. This is like what I have:

Recumbent Trikes - ICE - Adventure

I bought my wife one too. I would like to build something like this except pedal powered, not gas.

Decopod Tri-Pod - an art deco aluminum bodied scooter from Randy Grubb

Like my idol Howlin' Wolf said in a song, I'm built for comfort, not speed

[PJs]

Happy Holidays to all!!

Stefano: Without getting into a whole dissertation here I believe it needs a whole lot more R&D but we already have ultrasonics for soft tissue regeneration, sonics for gall stones, and a myriad of others actually being used by western style medicines. My system starts with the Mind and works with known frequencies and other systems for various things, but initially developed for myself after a bad motorcycle accident. I had seen a white paper several years earlier (10 year study) on the effects of low frequency for healing bone and soft tissue in joints. Frequencies between 20-40hz actually healed fractures 40% faster than conventional methods! Basically 30 minutes on my table and with the other systems built into it, I didn't hurt for a week! So I took it to the clinical level to help others and to generate further study. Personally I believe Royal Rife was on to something back in the day but like many things was squashed by greed and never fully studied and developed. I'd love to develop a hand held system similar to the ultrasonics used today...just not sure I have enough giddy-up nor Duckets (R&D ain't cheap) to "Get R Done" anymore.

C-Bag...I hear you about the comfort, but think my son and I are going to attempt a Drift Trike this year...maybe 2! The ICE mobiles look way comfortable!! Love the Decopod...too cool to Rule! More my style was his B702 though!! Oh My a Bugatti style with a 702Cu.In. V12...oh my...HO, HO, HO, I could deliver some presents in that! ~PJ

[rendoman]

small update first step of flange, i take the simple way
it would be a pleasure if he did not so much cold , my garage is frozen!

[C-Bag]

small update first step of flange, i take the simple way
it would be a pleasure if he did not so much cold , my garage is frozen!

Good pix. So "simple way" is not threaded onto driver? Bolted?

BTW, my garage is frozen too. I'm waiting for it to warm up so I can ride my trike down to the Post Office. That's my main use of it. Only 5mi. roundtrip, but all hills. 190' height gain and then down to the PO, then the same climb up and down back to my house. Down to 26 minutes roundtrip. Good for my truck( no short trip) and good for my waist and heart.

[PJs]

Thanks for the update pics Stefano. I hear both of you on the cold shop...mine was 45º F yesterday.

Looks like you made a mic holder also for your new EMC8000?

Curios what the depth of the cone will be based on the 1k-20k response on the driver? Is it some exact multiple of the wavelengths (1/f) of that frequency range (.0001 to .00005) to achieve some sort of resonance in the cone? With the exit port being 1.000" it seems you have the opportunity to tune the range a bit with the depth of the cone and of course the shape.

This all has me quite intrigued and really looking forward to how it all works out. Think I'll do some research on horn design!!

Thanks again! ~PJ

[C-Bag]

Curios what the depth of the cone will be based on the 1k-20k response on the driver? Is it some exact multiple of the wavelengths (1/f) of that frequency range (.0001 to .00005) to achieve some sort of resonance in the cone? With the exit port being 1.000" it seems you have the opportunity to tune the range a bit with the depth of the cone and of course the shape.

WOW, who was that masked man!?!?!?



you go Wiz!

[rendoman]

many thanks!

good physical activity is healty for the body! hope that the temperature raise fast ... here we'll have the next 2 months colder

the range 1k-20khz is the "recommended" by rcf, in my opinion this driver sound good from at least 1500\2000hz to 10000hz, no more. under 1,5k and over 10k in my opinion it sounds bad and not so loud. I post a couple of pic of datasheet of the "new type" with neodimium magnet, i had a paper of fq response of my ferrite driver, it has 108db\w\m (1less than neod) and a bit more range up to 10khz. In my opinion it needs courage to claim the driver usable from 1 to 20k ... but the component is intended for pro audio... than...

you're right, there is some "tuning" opportunity. In my big horn i tried to settle both front and rear chamber for working togheter, basically not only the dept but the volume. Horn is an "air trasformer", unfortunately i have to find my old papers where i wrote the formulas, i got weak memory . I remember that a front chamber (not compression) introduce a high pass filter, but in this case it's not our problem
Here we got a pre-tuned solid compression chamber that is the back of the driver, and we don't need to add a filter before the throat. With this kind of horn in my opinion only shape, cut-off and material are importants.
I tried some really ugly horns in plaster and cement, really bad internal surface as you can see, they sound good! I think that the real "tuning" is choosing the right cut-off frequency of the horn during design, not too low or the high freq will be cut, not too high or lowest freq of driver will be cut ...

...in few words, for this horn, we have to choose the cutoff with head (and shape for the right use). imho only bass horns have narrow range of fq (mine big are 150-350hz realistic) horns up to 1khz have less issues