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Post by Boomzilla on Aug 14, 2021 8:40:21 GMT -5
On the verge of testing an amplifier whose specs claim 1,200 WPC output at 2 ohms. But I don't have any 2-ohm speakers to test it with. Options:
1. Build a parallel resistor network to waste the extra power as heat (involves some HIGH wattage resistors...)
2. Put two other pairs of 8-ohm speakers in parallel with this original set (consider this the "omnidirectional" option)
3. Buy or borrow some extremely low-impedance speakers with high power ratings
Of the three, number two seems the most feasible. (1/total impedance = 1/impedance A + 1/impedance B + 1/impedance C) will give me a total parallel resistance of 2 ohms (with all speakers nominally 6 ohms each). Of course, this is a VERY crude calculation since speakers have impedance, not straight resistance. But it should be roughly approximate. But if I go this route, each speaker will need to be seriously robust in terms of power handling.
Since cheap speakers are not typically capable of high power, then probably better to go with the resistors instead? An L-pad would also work, but I know of none capable of 1,200 watts.
The other option is to just leave the spec unchallenged & move on without testing it.
Boom
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Post by mgbpuff on Aug 14, 2021 9:45:25 GMT -5
If you are going to do such things professionally, then you need a serious resistor grid. Otherwise I vote for the last option. Any loudspeaker route will either destroy loudspeakers or drive everyone out of your building or both and even then probably not come close to the maximum watts.
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DYohn
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Post by DYohn on Aug 14, 2021 10:14:40 GMT -5
What, so now you are testing ratings? How are you measuring power output? Comply with CTA-2006 standard as a starting place if you want to be in the business of "verifying" amplifier ratings. Don't be like some other idiots on the Internet who think they are experts because they bought an expensive audio analyzer, know what you are doing before you make a fool of yourself.
Sorry, CTA-2006 is for automotive gear which is where my head has been for a while. For home electronics it's AES. Research their standards as there are several that apply in this case.
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Post by monkumonku on Aug 14, 2021 10:32:03 GMT -5
On the verge of testing an amplifier whose specs claim 1,200 WPC output at 2 ohms. But I don't have any 2-ohm speakers to test it with. Options: 1. Build a parallel resistor network to waste the extra power as heat (involves some HIGH wattage resistors...) 2. Put two other pairs of 8-ohm speakers in parallel with this original set (consider this the "omnidirectional" option) 3. Buy or borrow some extremely low-impedance speakers with high power ratings Of the three, number two seems the most feasible. (1/total impedance = 1/impedance A + 1/impedance B + 1/impedance C) will give me a total parallel resistance of 2 ohms (with all speakers nominally 6 ohms each). Of course, this is a VERY crude calculation since speakers have impedance, not straight resistance. But it should be roughly approximate. But if I go this route, each speaker will need to be seriously robust in terms of power handling. Since cheap speakers are not typically capable of high power, then probably better to go with the resistors instead? An L-pad would also work, but I know of none capable of 1,200 watts. The other option is to just leave the spec unchallenged & move on without testing it. Boom As I recall, Mrs. Boom is very safety-oriented. I can't believe she would knowingly let you venture into measurement territory like this that might lead to your house burning down.  . And for what... does anyone really care if this amp can put out 1,200 watts into 2 ohms? Let Amir deal with academic stuff like that. |
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Post by AudioHTIT on Aug 14, 2021 10:59:25 GMT -5
I agree with the general sentiment, leave confirming specs to those with the proper test equipment, and methodology. Focus on reporting your impressions of the product, form factor, parts quality, appearance, and sound quality. There are things you could measure easily, like idle power consumption, or heat, but I’m one of the few interested in such things, and it would probably seem out of place to have odd measurement in the middle of an otherwise subjective review.
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Post by vcautokid on Aug 14, 2021 11:24:45 GMT -5
Power is something but not the only thing. So many factors govern our listening and reproducing our music. Meanwhile I am putting together another killer play list for my car.
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Post by ttocs on Aug 14, 2021 11:28:36 GMT -5
If the goal is to simply test the max power output, and not sound quality at that max output, then what about borrowing a wall of 412 guitar speaker cabs a' la Eddie Van Halen? Wire them for minimum impedance and use enough of them for the power to be measured. This one is 4Ω and can handle 320 watts. Just invite some of the neighbor kids to practice in your garage.  |
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Post by AudioHTIT on Aug 14, 2021 12:22:53 GMT -5
The question remains, even if you did have a speaker that could handle 1200W of power, how would you measure it? Instantaneous voltage across the terminals? How will you do that? Is the hold function on all but the best meters fast enough? That’s measuring peak power anyway. Oscilloscope? Would you run noise or steady tones through, even a high power speaker would probably balk at that. You’re back to load banks
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DYohn
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Post by DYohn on Aug 14, 2021 12:38:42 GMT -5
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Post by Boomzilla on Aug 14, 2021 12:57:01 GMT -5
Good points, all, gentlemen. Thanks for the course correction. No, I don't want to verify specs now that I consider it. In fact, not a single purchaser of this amplifier will ever run 1,200 watts into two ohms. You do that with "pro" amps for live stadium sound, maybe, but not with luxury home amps. It's well and good to know that the amp is stable at low impedance loads, and that it will handily drive any speaker that the buyer might choose. And that's enough mention needed in that area. If I had a Beverage electrostatic, I could test the amp for reactive loads, but I don't. If I had an Apogee speaker, I could test the amp into near dead shorts, but I don't. So that is that.
What the reader will want to know instead is "how does the amplifier sound in a home environment." And even that is going to be more speaker dependent than amplifier dependent. The best I can do is to use speakers that I'm VERY familiar with and then assess what differences this particular amplifier causes in them. Will the details of "how this amplifier affects this speaker" generalize enough to be useful to readers with different speakers? Maybe and maybe not...
What I can do is note:
How much wattage the amplifier consumes at idle (significant to those who want to minimize power consumption)
What temperature the heat sinks run at idle and under load (speaks to how much ventilation will be prudent)
Whether the internal electronic components appear to be of a quality commensurate with the item's price (may affect durability)
How long the warranty period lasts (speaks to the manufacturer's confidence in the product, or lack thereof)
If the amp had a fan (this one doesn't), I'd want to note the background decibel level of the cooling fan
And a summary of the perceived value of the amp vs. its cost.
Boom
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Post by DavidR on Aug 14, 2021 13:11:08 GMT -5
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Post by AudioHTIT on Aug 14, 2021 13:17:54 GMT -5
That sounds like a good tack ⛵️
I had a pair of Threshold 4000’s vertically bi-amped into Beverage Model 3’s for many years, they supposedly dropped down to a half an ohm somewhere in the high end, but the Thresholds never thought much about it, though they did run hot.
When I see the title of this thread I think of Bart Simpson prank calling Moe’s bar, I can’t think of a variation for “low impedance”, but my favorite was Moe yelling out “I need Amanda Hugginkiss”!
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Post by Boomzilla on Aug 14, 2021 16:22:10 GMT -5
...I had a pair of Threshold 4000’s vertically bi-amped into Beverage Model 3’s for many years, they supposedly dropped down to a half an ohm somewhere in the high end... Most electrostatics do. ...the Thresholds never thought much about it, though they did run hot. Most amps do... But it definitely sounds like the Thresholds WERE the right tool for that particular job. |
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Post by AudioHTIT on Aug 14, 2021 22:29:53 GMT -5
...the Thresholds never thought much about it, though they did run hot. Most amps do... But it definitely sounds like the Thresholds WERE the right tool for that particular job. 200 WPC Class A, 36 output devices per channel, talk about low output impedance. |
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. And for what... does anyone really care if this amp can put out 1,200 watts into 2 ohms? Let Amir deal with academic stuff like that. 
