Cube Nenuphar speakers

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steve s
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#16 Re: Cube Nenuphar speakers

Post by steve s »

iansr wrote: Wed Dec 19, 2018 1:06 pm The wisdom I’ve received over the years leads me to conclude that passive electrical crossovers are a bad thing
Just like to add that on my experience this statement is not true. I have loads of hi end single drivers and diy multiways speakers/ drivers... its all about good drivers that are well implemented.. in my view of course
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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Nick
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#17 Re: Cube Nenuphar speakers

Post by Nick »

Fits into the general observation that amps will often have increased distortion at low impedances.
Can be the result of more or less feedback. Amps that have a inherently low output impedance may work well into reactive loads without large amounts of feedback. If you imagine the amp consists of a voltage source with a series resistance, and the load as the second half of a potential divider made with the series resistance. The feedback will be taken from the centre of those two resistors, so if the lower resistor is half'd (say from 8R to 4R) then the amount of feedback will be 6dB less just because of the change in load.

One of the hidden reasons why a amp will get upset driving a short circuit, you have removed the feedback and the amp will try and run open loop with the expected huge increase in gain that will give.

Driving a reactive load is far harder than just a resistive load because of the phase difference between I and V.

Understanding amp stability is a big subject I am still learning.

Current limiting i also a lot more complex than it may first appear. Generally its not current limiting that you try and achieve, but safe operating area limiting. For example the mosfets I use in the p6 amps are rated at 100A continuous, 275A pulse, but a max dissipation of 735W, so with 70v rails and the output at 0v, max current is only 10A. Into a restive load you would never have output current with 0v on the output, peak output of (say) 65v into a 1R load would be 65A, with only 6v across the device (70-65) thats a dissipation of 325W so all looks good. But the key is resistive load. Once I and V are not linked via ohms law, the load could draw 10A with the output at 0v so things get more fun.

The best way I know of breaking a amp is connecting the two channel outputs together. Couple one input to 0v, and a full scale sine wave on the other input, The output thats trying to stay at 0v, will put its output devices under worst case conditions with max current and max voltage at the same time.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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Ray P
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#18 Re: Cube Nenuphar speakers

Post by Ray P »

Anyway, it looks as though HiFi Collective are going to have the Cube range;

https://www.hificollective.co.uk/drive- ... ivers.html
Sorry, I couldn't resist!
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Nick
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#19 Re: Cube Nenuphar speakers

Post by Nick »

Ray P wrote: Thu Dec 20, 2018 10:11 pm Anyway, it looks as though HiFi Collective are going to have the Cube range;

https://www.hificollective.co.uk/drive- ... ivers.html
Yep, I have mentioned to Nick L that there may be a couple here wanting a listen some time.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
iansr
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#20 Re: Cube Nenuphar speakers

Post by iansr »

For those interested, these speakers are going to be on demo for the next couple of weeks at Wilkinson’s Audio in Bacup. I’m going for a listen next week.
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