Still astounding. Both in terms of the solution and the sheer bloody mindedness of the people creating this to do something so difficult to create things that don't live long enough to even be directly detected 🙂
I do like clockwork cars. I have even driven a car where I wrote some of the code for the ECU. However when you are late for work checking the weather forecase to see which jets would be optimal for the commute does get boring*
* I know most are not that anal about carb tuning 🙂
Jim Williams gave an ISSCC talk on tuning dual SU carbs on his Jag by carefully cutting the viscosity of the damping fluid as the car aged.
SU's did require a whole extra set of skills. Very clever when they worked! I have always wanted a 3" SU as used in the early spitfires as an ornament.
EDIT: P.S. I am of the Bob Pease school of running cars a very long time.
EDIT: P.S. I am of the Bob Pease school of running cars a very long time.
My Gremlin used a Weber, I once forgot a plug when I replaced it and covered the engine with leaking gas. Lucked out on that one.
Scott, was your Weber carb a 28-36 DCD dual throat carb? These carbs were easy to adjust compared to SU's.
JN
3 different twists. Two pairs for the woofer and one for the midrange. The dual shields are actually a coax with an impedance of X ohms. Size limit due to conduit issues.
Now for your bonus question, what impedances am I aiming for in the loudspeaker system?
(Hint given the same voltage which is louder a 16 or 8 ohm compression driver horn combo?)
3 different twists. Two pairs for the woofer and one for the midrange. The dual shields are actually a coax with an impedance of X ohms. Size limit due to conduit issues.
Now for your bonus question, what impedances am I aiming for in the loudspeaker system?
(Hint given the same voltage which is louder a 16 or 8 ohm compression driver horn combo?)
Why two pairs for the woofer? Is it one circuit, or two?
I hate size limits due to conduits, don't you?
The midrange would be better off with the two pair, you'd just have to suck up the losses in the bass.
And why two coaxial shields? The only time we need that is when we have to double bond renishaw 1 micron resolution absolute encoders down in the tunnel, but that technique only works if you have one, we typically run 6 at a time.. One unit's ground noise current flowing in the external braid shield doesn't couple to the internal wires as long as the bundle's been rounded with chase fibers...but once a second run is installed in the tray, that concept no longer works..
I see two answer possibilities here. First, one arrived at using correct engineering skills and understandings...
Then, what you choose to do...😱
badaboom...low hanging fruit, I had ta take it....😀
Used to have that pesky power equation inked onto my hand...but I eventually had to wash...darn it..
John
Woofer is two units with the same signal. The midrange suffers little air absorption loss and is of very limited range. The "HF" comes in at 1,100 Hz. Woofer quits around 600.
With 16 ohms you have half the current but twice the voice coil windings! So the same level. (I'll help you through those pesky physics things...)
With 16 ohms you have half the current but twice the voice coil windings! So the same level. (I'll help you through those pesky physics things...)
Back in about 1972 my wife was teaching first year high-school German. She said in German 'Princess Summer-Fall-Winter-Spring' and the class just looked at her. So she repeated in English 'Princess Summer-Fall-Winter-Spring' still nothing. So she said 'Howdy Doody' but none of the kids ever saw the show.
So you build in the smiley face eq layer by drivers..I usually use the eq to do that.
I guess one could assume that twice the windings is the same mass, and that the 8 ohm version has a gap twice the width of the coil requirements, and that a vendor would use the same gap for two different thickness coil packs.
In my work, I could never make such blatant non-engineered choices. I would require specific gap field strength, specific coil masses...and, I would never assume that doubling the number of turns produces double the vc inductance. It quadruples. Who is your vendor?
Hey, thanks, that would take a load off my grandkids....
John
I'm not surprised that you don't remember. You are not a car guy. '-) I ADDED the Weber carb to my SAAB Sonnett sports car back in 1968, replacing the single throat Solex. Big improvement. More power, better mileage.
JBL & ferrofluid! Expecting loudspeaker drivers to be within 2 ish dB is reasonable. 1% flat out rolling on the floor laughing. 5% humor. 10% doable but requires a bit of extra effort.
As to inductance it does go up but then there are shorting rings to reduce it, all of which matters little when the air loss limits you to 8,000 cycles per second HF response. (300-600 watt power handling!)
As to smiley face HF eq can exceed +20 dB, midrange -10 dB and woofies flat.
So, change about 12 things, then claim that halving the power to the driver gives the exact same response..
As I said, ask JBL what vc impedance can we expect over unity? Hey, if 16 needs half the power, then 32 needs 1/4, then 64 needs 1/8th...
All they gotta do is figure out how to give neo magnets permeability over 1...
I love it when you speak hi-fidelity...
When I used to do gigs, smiley was best for listener fatigue prevention..
John
ES,
Your not seeing any of the problems of the past Ferro Fluid of viscosity rise with age and heating that was locking up so many tweeters in the past? One of the reasons I've stayed away from that solution and also just the cost of having to use 8cc of fluid to fill the gap in my long gap magnet structure, not a cheap endeavor.
Your not seeing any of the problems of the past Ferro Fluid of viscosity rise with age and heating that was locking up so many tweeters in the past? One of the reasons I've stayed away from that solution and also just the cost of having to use 8cc of fluid to fill the gap in my long gap magnet structure, not a cheap endeavor.
JN
Have done this with the 16 ohm vs 8 Ohm for years. Yet to see a difference where I use them. Of course there are exceptions. But would have expected you to catch on to the scale of my systems.
Kindy,
Have used ferrofluid for decades. In my applications don't see the lockup as do low powered users.
ES
Have done this with the 16 ohm vs 8 Ohm for years. Yet to see a difference where I use them. Of course there are exceptions. But would have expected you to catch on to the scale of my systems.
Kindy,
Have used ferrofluid for decades. In my applications don't see the lockup as do low powered users.
ES
(In that case, may I recommend taking the long way home in your VW Bug with extended wheel-base, instead of a short cut)
IIRC it was at the same voltage. So you are implying here that a 16 Ohm speaker has twice the efficiency as the same driver in it's 8 Ohm variety. If you were correct, I would want 16000 Ohm drivers.
Last edited:
As to ferrofluid, it is good for bad tweeters only. Mechanical friction in speakers is highly non-linear and should be avoided as much as possible. In other words, keep that mechanical Q as high as you can, and use Qes and enclosure parameters to get to the target system Q.
- Status
- Not open for further replies.