NVA specs

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_D_S_J_R_
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Re: NVA specs

Unread post by _D_S_J_R_ »

Just to show how careful you need to be in interpreting specs.

A certain small active speaker was launched ten or eleven years ago and the claim was made for the bass amp having 250W into the bass unit rated at 4 ohms. Maths was given on their forum for theoretical power output relative to rail voltages and loading but these things were never given for third party review despite reservations by some of the PFM doubters. A few years on, an owner tested his pair the conventional way and found the actual steady-state power was less than half the figure given at 4 ohms, sagging to 72W at 8 ohms continuous and the main driver was only 4 ohms at DC, being 6 ohms in the midband and 8 ohms near the upper limit before crossover.

So, the 250W 'instantaneous' power might be approached on a rim-shot or something similar had the driver been a true 4 ohm unit, but in reality it and the amps were nothing like it - and never needed to be... The 'sagging' power supply was actually a good thing for the reliability of the speaker as a whole and 72W could be very high volume, but hopefully you get my points above as to the futility of basic specs on paper as they can be spun to partly deceive...
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kimangelis
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Re: NVA specs

Unread post by kimangelis »

I'm not totally convinced that specs. per se don't play a part in an objective assessment of an electronic product. Yes Richard, I agree that using ones ears is the only true path to enlightenment. But some people (rightly or wrongly) initially judge a product on specifications of a given current through a particular resistence via a particular path.

To analogize, the only way to judge a car, like a Spider or a Celica, is to get into it and drive. But initially an evaluation is dependent upon figures such as mpg, 0-60, gearing ratios and the like (objective), with more subjective analyses of the effects of wheel size, tyre ratios, fuel injection (and carburation), engine type (VVT etc.)

No I wouldn't buy a car based on numbers and opinions. However it would rule out certain models and specs. Ditto hi-fi I feel. There's nothing wrong with supplying true measurements of NVA products which will reflect an objective analysis, to guide (persuade?) same toward a more subjective analysis based on (earlier) objective figures?

Your return-if-not happy guarantee is exemplarary, but I think that not supplying objective measurements if requested, is an error.
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Re: NVA specs

Unread post by Daniel Quinn »

Your wrong. Largely because manufactures specs ain't comparable, despite the illusion that they are.

Even ones done by the press don't offer the chance to compare. Can you tell the difference between a tt that spins at 33.38 and that spins at 33.31

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Dr Bunsen Honeydew
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Re: NVA specs

Unread post by Dr Bunsen Honeydew »

You don't drive a hi-fi system, silly comparison. Even the car makers have been proved to make it up and tell lies, well hi-fi is 10 times worse.

Test equipment and what it tells me are useful sometimes to me but not to any of you unless you design, build, or repair product.

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kimangelis
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Re: NVA specs

Unread post by kimangelis »

It's not a silly comparison at all. By analogizing car driving I was comparing experience. Listening and driving are both subjective experiences. When driving or listening you are (objectively) blind. The fact that car companies or hi-fi companies tell lies is shameful but in the context of this arguement, irrelevant.

Richard, you are in the world of present hi-fi, unique. NVA products reflect this and good grief, I should know. However I was arguing that a great many people make initial selectictive decisions based on what they read and not what they perceive or hear. From there they move on (or sometimes not) to listening.
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Re: NVA specs

Unread post by Dr Bunsen Honeydew »

I thought that was the point of the thread, so you are stating the obvious. AND cars and hi-fi are a totally different experiences, needing totally different choice decisions. Choice car decisions with even the bent specs work, you can relate differences with the driving experience, YOU CAN'T DO THAT WITH HI-FI, the comparisons fall apart, the specs don't relate to any reality.

I seriously couldn't give a feck if people want specs, you should know me by now, they don't get what they want if it is delusional, they get told the truth - exactly what this thread is about.

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Re: NVA specs

Unread post by Rectified »

Daniel Quinn wrote: Sun Mar 04, 2018 2:11 pm It takes some balls to sell without specs most equipment is sold via the specs , despite they being meaningless drivel.
Aye & takes a donk to buy just on specs

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Lindsayt
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Re: NVA specs

Unread post by Lindsayt »

DSJR, the thing with the 250 bass amp power spec you mentioned is that the acolytes of this brand would go on internet hi-fi forums and go on about the 250 watt spec and give that as an indication of the "very high" quality of the tiny active speakers in question. And sneer at people with 80 watt (continuous into 8 ohm amplifiers) amplifiers in passive systems for having a lower quality amplification as well as not having enough power to recreate the full dynamics of the music.

It was like "These speakers are amazing value because you get 325 watts per channel for £1200".

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Re: NVA specs

Unread post by Geoff.R.G »

Specifications have their uses, one wouldn't use a transistor rated at 1A in a circuit that was going to carry 4A continuously nor would the use of 0.5 cross section wire be used in a 16A circuit. However, just because an amplifier is rated at 150W doesn't mean that it will deliver that power into a real world load ("real" load being something very different). I have driven speakers rated at 35W* with a 150W amplifier at realistic levels without destroying them, it is a case of listening for the first signs of distress and pulling the output back. Specifications, unless they are fully understood and derived by a consistent method, are pretty meaning less. Leave them for the designer/s who will, one hopes, know what they are doing.

*if you used that much power in a domestic setting you would have the neighbours round pretty quickly though your chances of hearing the door bell would be small.

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Re: NVA specs

Unread post by montechristo358 »

probably as good a place to ask as any. I've not found anything that states what class amplification design NVA amps use?

I await a response saying who cares its how they sound, and I'd agree. But I'm curious none the less
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