John Curl's Blowtorch preamplifier part II

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diyAudio Member RIP
Joined 2005
Even the D'Agostino amps failed it. But for whatever people say about JA, he does at least try and give electronics a hard time, and if it blows up he tells people.
I wasn't going to mention any names, but yes, I was thinking of that one in particular, the copper Venturi yada yada ones. A beautiful case, although some complained that it looked like a bathroom scale.
 
Brad,
I'll let that unnamed person who can do the electronics on my speaker figure out if the heatsink is large enough to handle the amplifier power! I sure hope so, but like I said I can always increase the height of the fins if more dissipation is necessary. I took the actual dimensions for the sink off an American extrusion companies website. The vertical fins should help cool them a bit better than a horizontal placement.
 
Christophe,
I would have to go back to the Stereophile magazine and look up what that test was exactly. I'm not sure that it isn't so governmental designed test though. Bcarso would know the particulars of that test. I do know it is some test that maximally stresses the output devices and I'm not so sure it is really a realistic test under normal music signal usage. Kind of like talking your cars engine to redline and holding it there to see if it get hots after a prolonged amount of time, like anyone really does that.
 
It's part of the FTC test for power.
"The FTC establishes fair advertisement practices for home audio power ratings. This is described in the FTC document 63FR37233, 16 CFR, Chapter 1, Part 432.
It defines how the amplifier should be tested for power and signal distortion.

The FTC requires that the amplifier be pre-conditioned at one-eighth of rated total power output (for a multiple-output system, all channels are on) for one hour using a sine wave at a frequency of 1,000 Hz
."
 
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Besides reducing 1/3 power preconditioning to 1/8th...... I like the part which --- "exempt advertising from.... " really took the teeth/meat out of it to become worthless and meaningless power rating.

The new FTC power rating should now be forgotten.

As a designer or company, I would still do the 1/3 power test for safety and reliability and then also give full specs/ratings of average power, impedance and distortion etc to be credible.


THx-RNMarsh
 
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SE,
I thought you saw my speaker design idea already? I'm going to do another grill as an option for those who don't like the wire form, the same shape with a normal grill cloth. About 10% of the people who have seen this don't like seeing the speakers themselves. I also removed four of the screws around the tweeter, I can't get rid of the four in the center but did the outer four.

Those look freaky and rather intimidating. The demeanor would be a strong deterrent to have them anywhere visible, or even in my house.
 
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