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Kevin -- Tip: a cheap full load resistor
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Dana K6JQ
I measure ~915W power use (P4400 Kill-A-Watt), whichUnless the resistor coils are bifilar wound to minimize inductance then the measured distortion using such a load on any power amp will show several percent distortion beacuse the load is not resistive. If this is of no concern, yes, a pretty darn good load indeed. -- Best regards, Goran Finnberg The Mastering Room AB Goteborg Sweden E-mail: mastering@... Learn from the mistakes of others, you can never live long enough to make them all yourself. - John Luther (\__/) (='.'=) (")_(") Smurfen:RIP |
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On 8/22/2012 9:00 AM, Goran Finnberg wrote:
Interesting point. I intentionally left out any discussion of reactance since I expect any conventional speaker is far more reactive than the heating element. Once again employing the high-precision (sic) P4400 Kill-A-Watt, the waffle iron shows a power factor of 0.99 - 1.00, which at 60Hz seems to be pretty-much entirely resistive. So, now you've done it, I had to break something resembling a real instrument (LCR meter) and get some objective numbers! At 1.0KHz, my Black and Decker waffle iron shows 15.57 + j0.031 ohms. That's ~ 5uH total inductance, and that includes the line cord - which admittedly introduces some parallel capacitance which could *reduce* the apparent inductance. So I measured at 60Hz, 120Hz and 250Hz and found the same ~5uH inductance, so I don't think we're seeing a significant influence from the line-cord capacitance. At 15KHz, the apparent inductance drops to ~3.5uH, still substantially below resonance. I'm going to go out on a limb and suggest the inductance of the heating elements themselves is less than 5uH once the line cord is eliminated. Do you still think that the reactance of the waffle iron is a significant issue at audio frequencies? 7.8 ohms + 2.5uH each :-) Dana K6JQ |
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All right guy's: On the subject of that Iron & load. I have a high quality load test resistor, a older scope. I don't know the proper way is to hook it to amp. in question due to being new to this hobby of a couple of years now. Maybee if I can figure out one day how to hook it to amp. and scope I will try that test. What I need is a testing book I can buy to figure out how it is done the right way. Thanks to all e-mails I am progressing in LTspice now at least. Thanks,
Best Kevin ________________________________ From: Dana Myers <dana.myers@...> To: LTspice@... Cc: Goran Finnberg <mastering@...> Sent: Wednesday, August 22, 2012 12:38 PM Subject: Re: [LTspice] Kevin -- Tip: a cheap full load resistor ? On 8/22/2012 9:00 AM, Goran Finnberg wrote: Interesting point. I intentionally left out any discussion of reactance since I expect any conventional speaker is far more reactive than the heating element. Once again employing the high-precision (sic) P4400 Kill-A-Watt, the waffle iron shows a power factor of 0.99 - 1.00, which at 60Hz seems to be pretty-much entirely resistive. So, now you've done it, I had to break something resembling a real instrument (LCR meter) and get some objective numbers! At 1.0KHz, my Black and Decker waffle iron shows 15.57 + j0.031 ohms. That's ~ 5uH total inductance, and that includes the line cord - which admittedly introduces some parallel capacitance which could *reduce* the apparent inductance. So I measured at 60Hz, 120Hz and 250Hz and found the same ~5uH inductance, so I don't think we're seeing a significant influence from the line-cord capacitance. At 15KHz, the apparent inductance drops to ~3.5uH, still substantially below resonance. I'm going to go out on a limb and suggest the inductance of the heating elements themselves is less than 5uH once the line cord is eliminated. Do you still think that the reactance of the waffle iron is a significant issue at audio frequencies? 7.8 ohms + 2.5uH each :-) Dana K6JQ [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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On 8/22/2012 11:42 AM, Kevin Byrne wrote:
I don't understand the difficulty with attaching a test load - presumably you replace the speaker with it? BTW, LCR meter applied to Sony SS-5000F speaker showed a *very* reactive load over the audio range, likely largely influenced by the crossover network. At 1KHz, I saw 14.93 + j 7.851 ohms, at 5KHz I saw 11.6 - j4.62 ohms. etc. Cheers. Dana K6JQ |
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rainbowsally
A speaker is also a dynamic mic, so the paper itself will act as a reactance due to its mass and the push back of the air plus any resonance in the cabinet, the room, etc. Sounds reflected will also be "felt" by the voice coil (because it's a transducer) to some extent which could possibly be infinitessimal, but also could possibly be significant, depending....
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These things, since they will lag behind the stimulus (in differing degrees and phases) will seem like complex reactances though resonances may seem to be tank-like even if they are just the resonance of the cone itself (usually heard as a nice damped thump for a woofer). I think these mechanical effects will swamp out most of the true electronic reactances. I'm not set up for testing, but you could try restricting the movement of the cone with your hand and seeing the difference in the readings. The changes in magnitudes and phase could be a clue as to how much of it is actually mechanical. And then make a Spice model of it! :-) Dana Myers wrote: On 8/22/2012 11:42 AM, Kevin Byrne wrote:All right guy's: On the subject of that Iron& load. I have a high quality load test resistor, a older scope. I don't know theI don't understand the difficulty with attaching a test load - presumably you |
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--- In LTspice@..., "aurora_viii" <aurvii@...> wrote:
Hello, Please stop on these threads: ...a cheap full load resistor ...Power Supply Ripple ...audio amp... Every further message and many of the previous posting may be deleted soon due to be off-topic. Best regards, Helmut |
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Can you guys take this amp private? ?You are cluttering up my mail box. ?:-( ? ?Jack
________________________________ From: Helmut <helmutsennewald@...> To: LTspice@... Sent: Sunday, August 26, 2012 7:37 AM Subject: [LTspice] Re: Kevin -- Tip: a cheap full load resistor ? --- In LTspice@..., "aurora_viii" <aurvii@...> wrote: Hello, Please stop on these threads: ...a cheap full load resistor ...Power Supply Ripple ...audio amp... Every further message and many of the previous posting may be deleted soon due to be off-topic. Best regards, Helmut [Non-text portions of this message have been removed] |
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rainbowsally
Received and understood, Helumut.
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But it would be nice to be able to have a place to discuss this kind of stuff. We can get resistors, caps, and transistors, etc. from vendors, which is supported here, and in fact we have libraries full of stuff that includes how to get these things. But no pricing info (which likely changes all the time so it's no biggie). What we don't have is crosses for various components that are easy to look up (from comparisons of power, max voltage, gain where applicable, etc) and what if a toaster or a waffle iron ends up being a very affordable cross for a thousand watt 4 ohm resistor. If we make that a Spice model, would it suddenly be on topic? I'm not trying to make problems, Helmut, it should be obvious that I'm trying to make solutions. Sorry if this topic is aggravating to you in this forum, but if you created a spinoff group and listed it officially on the main page, maybe we could share these interesting plug in compatible, non commercial crosses and save enough money to buy a gazillion 2n4401's (200 bucks can buy a lot of zits) from whatever corporate vendors we have spice libraries for. This is probably the third or fourth appeal to you on this subject of where we might share this kind of info and you have not offered a suggestion or a subforum (like LTSpiceFiles). Can we compromise on this somehow? The folks here are very interesting and helpful but keeping track of LTSpice forum members that want to talk off list is very inconvenient. Helmut wrote:
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rainbowsally
We did, Jack. Want to be included in the discussions? :-)
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If so, tell Helmut. The most recent offlist discussion was about current limiting in the power outputs (eliminates need for fuses in some cases) which could very well apply to non-audio stuff as well. Implementation was one small resistor (current sensing) and one 200 mW bjt (to turn off non-blown circuits) and included a small LTSpice file to demonstrate the effectiveness of this approach. To tell you the truth, I've been a member here like forever and I guess I don't even know that the topic is. I'll post this to the forum in case any others want to be included in what is currently an offlist conversation on this offtopic stuff. PS. I still haven't heard from Kevin. He's either busy having success or... Well, that's probably it. That's when we go silent isn't it. :-) Jack Fanning wrote: Can you guys take this amp private? You are cluttering up my mail box. :-( Jack |
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rainbowsally
It will be unmoderated. Will you be available to be a second owner in case something happens to me so it can be shut down if it gets out of control (trolls, spam, etc.)?
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Helmut wrote: Hello Kevin, |
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For the record Helmut ?I am not a computer geek, electronic geek but I have been getting 100 to 300 E-mails?a day quite a few of the stupid kind. I do not know how to spot spam, hackers or any thing else. I do not reply like you said due to my understanding your words and respect for others. Please accept my apology for just being new, not a smart ass.
Not my style. I did receive a lot of help thou, and have a number of books on order and am a lot further along in my study's of audio equipment. I am a disabled Vet., a certified auto mechanic and know the value of study and asking questions. Best to you and advise as I am a person who listens and takes a beating and changes when I am wrong Kevin [Non-text portions of this message have been removed] |
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rainbowsally
Yeah. Us old hippies need to stick together. :-)
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Absolutely the best of luck to you, Kevin. Email me offlist if there's anything you think I might be able to help with. Kevin Byrne wrote: For the record Helmut I am not a computer geek, electronic geek but I have been getting 100 to 300 E-mails a day quite a few of the stupid kind. I do not know how to spot spam, hackers or any thing else. I do not reply like you said due to my understanding your words and respect for others. Please accept my apology for just being new, not a smart ass. |
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