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The dumbest thing I've ever seen in amp construction....
The dumbest thing I've ever seen in amp construction....
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Old 13th June 2019, 06:32 PM   #101
davada is offline davada  Canada
diyAudio Member
Join Date: Jul 2004
Location: Fort St John, BC Canada
The insulated laminates are to reduce power lose in the form of heat in the transformer core. The insulation prevents eddy current circulating between laminations. It doesn't matter if the outer edges of the lamination are shorted. This would not increase the power lose much because eddy current are local short path circular currents. Not conduction.
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Old 13th June 2019, 07:48 PM   #102
Gnobuddy is offline Gnobuddy  Canada
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Join Date: Mar 2016
Originally Posted by mountainman bob View Post
...could it be that setup works as a front ‘wing’ of sorts to keep the nose down at higher speeds?
I'm no aerodynamics engineer either, but aerodynamic lift / downforce is proportional to the square of the velocity, so in general there is very little lift or downforce from automotive aerodynamic aids until speeds get far above legal limits on public roads.

Sadly, you can still manage to get enormous aerodynamic drag, simply by having a frontal cross-sectional area the size of a barn door. Which is more or less what the Jaguar i-Barn does.

To put some numbers to it, I read somewhere that the Jaguar i-Blob is limited to a top speed of 124 mph. Using the aerodynamic lift equation (f=1/2 rho Cl S v^2), a very efficient spoiler with an area of half a square meter and a lift coefficient of unity (1.0) would generate about 95 kg of downforce, the weight of a fat man.

That sounds good until you compare it with the ludicrous 2760kg curb weight of the i-Lump. (Not far shy of 6000 lbs if you prefer imperial units. Or just about the weight of TWO Volkswagen Beetles if you prefer a historical comparison.)

This means, at 124 mph, the downforce from our hypothetical very efficient nose spoiler is a paltry 3.5% of the weight of the i-Lard. At legal speeds (i.e. about half of 124 mph), downforce drops four-fold, so less than 1% of the i-Fatty's gross weight.

Incidentally, the i-Blubber reportedly has a frontal area of cross section of about 2.4 square metres - about five times the area of my hypothetical spoiler. Drag coefficient is a claimed 0.29. Put those numbers together, and aerodynamic drag at 124 mph would be about 132 kg.

At 124 mph, it would require about ninety-six horsepower to fight that much drag force.

(And we are not counting additional drag from the enormous tyres as they thunder over the overburdened asphalt.)

For reference, the Volkswagen XL1 - an experimental project vehicle which put drag coefficient above design fads - managed a drag coefficient of 0.19, and achieved greater than 300 miles per gallon. Many of today's production cars have drag coefficients in the range of 0.22 - 0.24. Not stellar, but still considerably better than the i-Piggys 0.29.

I would love to hear actual hard numbers from the aerodynamics engineers at Jaguar who measured and wind-tunnel tested the i-Juggernaut, but I'm sure they would prefer to maintain their silence and keep their jobs.

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Old Yesterday, 12:03 PM   #103
Scott Novak is offline Scott Novak  United States
diyAudio Member
Join Date: Feb 2009
Location: Minneapolis, MN 55404
What seems to have been overlooked is that an important reason for welding ONE corner of a transformer is for safety. If a transformer winding shorts to the core it doesn't matter which lamination it shorts to. With a welded corner EVERY lamination will be shorted to ground, reducing the electrocution hazard. Only one corner being welded is not going to affect the transformer that much.

I've worked for two transformer companies making laminated transformers and a power supply company making their own high frequency magnetics.

A top quality transformer will be vacuum varnished for improved reliability and reduced noise output. The varnish will usually cover any nicks in the wire's insulation.

The next step down is varnish dipped transformers. The varnish doesn't penetrate as well. I tend to think, why bother.

Cheap transformers are welded together instead of being bolted together. They are often not even varnished at all, making them less reliable and much noisier

Guitar amplifiers as a rule suck. Using only a woofer is inane. To make up for the lack of treble response from the woofer the signal must be equalized and additional output voltage used at higher frequencies. The causes the amplifier to clip prematurely from high frequency content while the average volume level is still low. Adding a midrange and tweeter allows full output of the amplifier before clipping occurs.

Back in the 70's I played guitar through an Altec Lansing 1208 Bass horn cabinet with a 511B mid/hi horn with an 808-8B mid/hi frequency compression driver. I used my own vacuum tube preamplifier with a squalid state power amplifier. The squalid state power amplifier was a mistake, but I was still young and stupid then. Overall I still had a tone that I much preferred over they typical guitar amp setup. The efficiency of my speaker cabinet was so great that I was never able to play at full volume with only a 100 W amplifier.

Scott Novak
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