Pass "DeLite" Amp from BAF

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#85
I had some 300w bulbs for a never built enlightened Zen, and cold they seem to measure about 4 ohms,.. I remember the bulbs at the show being big, but marked 150w So maybe Nelson can "enlighten" us. I realize that the bulb's resistance changes a little when it gets hot, but it isn't going up that much...I don't think..
hmm

Mark

/Anyway , I suspect it is 150w bulbs..
 
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#86
Well, I've posted this before but it may be of interest now 😉
 

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#88
I did not try any "dynamic" testing but I think your right :bulb: It would be interesting to see at least some pulse testing types of response. Maybe I'll get off my butt this weekend and try something:smash:
Hey as long as I have your attention, what do you think I should try? I haven't really thought about it much. Hmmm
Start with an amp or so (Idle current) and hit it with a step up to 2A? A step down to 0A. See what the rise time/fall time looks like? We could calculate Thermal Capacitance or whatever :bulb:
 
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#89
tryonziess said:
The ceramic bases are extremely common. Hundreds of old apartment buildings here
have these bulbs hanging from the ceiling on all of the hallways.
Click to expand...
Thanks, Tad. I really like those bases a lot better than the ones available here.
Since I'm lacking the resources to come over to the US to vandalize old apartments
- could someone please name a supplier for NEW ones that are NOT attached to old ceilings? 😀
 
#93
flg said:
I did not try any "dynamic" testing but I think your right :bulb: It would be interesting to see at least some pulse testing types of response. Maybe I'll get off my butt this weekend and try something:smash:
Hey as long as I have your attention, what do you think I should try? I haven't really thought about it much. Hmmm
Start with an amp or so (Idle current) and hit it with a step up to 2A? A step down to 0A. See what the rise time/fall time looks like? We could calculate Thermal Capacitance or whatever :bulb:
Click to expand...

That's a good start. I would expect second harmonics to be way up there if there is much modulation. My grandmother only had two outlets in her whole basement so I used to buy 300 Watters so I could see, they got HOT!.

Maybe there's a way to work a panel light into the input to compensate. 😀
 
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#94
Variac said:
I had some 300w bulbs for a never built enlightened Zen, and cold they seem to measure about 4 ohms,.. I remember the bulbs at the show being big, but marked 150w So maybe Nelson can "enlighten" us. I realize that the bulb's resistance changes a little when it gets hot, but it isn't going up that much...I don't think..
hmm

Mark

/Anyway , I suspect it is 150w bulbs..
Click to expand...

A 300W bulb should be 48 ohms when hot, assuming 120V RMS line.
 
#95
Well, we aren't running the bulbs at full output, or close to full output, so they won't be as hot as Scott's Grannies basement and I guess not the 48 ohms that 120v might give.

So Nelson's amp has two 150 w bulbs I believe - one for each channel. right? (its a stereo amp) And he calls the bulb out as 20 ohms.

So I guess my 300w bulbs have less resistance, so it looks like I'll have two 300's per channel in series. Appears that more wattage is more linear. I'll then have a "300W SED" amp which has specs like a "300B SET" amp. Hope they still glow enough though..
 
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#98
As my experimenting showed also 😉 For the 300W: 25V/1.1A = 22.7 ohms
There definatly seems to be some non-linear functions at work with the heating etc.
I'm going to try to experiment with some bulbs and the heating elements and their response to rapid changes to applied voltage/current this weekend if possible. I don't have any ability to do THD at the moment but some curves/scope pics in the audio bandwidth rather than several seconds might uncover something interesting 😕
 
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