What makes a system sound 'fast?'

All systems are bandwidth limited. I don't think that Naim are exceptionally challenged in this area.

Anyway I'm still not sure I could spot 'fast' or 'slow'. Obviously I have a full range system, but it simply seemt to play the notes in the right order, sometimes even more than one at once.

Paul

 

hmmm cds cut off at 20 khz, power amps at anything from, 25 khz to 250 khz, speakers, 20-30 khz.

I think they mean active band limiting as in a capacitor on the input to the power amp.

is there any point in having power amps going to 100+khz when cds and speakers don't ??

 

Paul,

Do you feel that an amplifiers ability, to attain it bandwidth limits with great ability, would not be benifical?
And try HEXFETS these are rather good
AS for this flabby and not right bass v's Tight and lean, you guys can have either, I'm happy with both thanks

 

Fair point - but my power amp is rated at DC-4MHz and it's the cleanest amp I've ever heard! The important thing may be that that then allows <1degree phase shift at 20kHz. 800V/us slew rate may help as well.

 

Well now, at 20 kHz, one full cycle is 50 us (u=micro). From 0V to maxV will be one quarter cycle or 12.5 us. So your power amp needs to be able to go from 0V to whatever the maximum is for the current output level in 12.5 us. This is the fastest rise time you can get out of a CD player (almost).

A 100 Watt amp would need about 28 V into 8 ohms. Even a crap 100 Watt amp can muster 28 V in 12.5 us.

 

very true, Chris, there is more to it than slew rate.

I know, why don't we ask naim how they do it? how they make something pratty? see how they reply (and if they really know)

 

But does Naim gear really play a tune better than others?

Or are we somehow led to believe it does after 30 years of marketing hype and tune Nazi dems at hifi shows. After all, Naim does sound so different to my ears that I reckon it would be difficult to do a blind test and not pick out the Naim gear.

But then, knowing it's Naim, and the 30 years of spiel that has become synonimous with that name, do we subconciously focus on the "tune"?

 

tha'ts something that has struck me, does knowing the general 'house sound' of kit lead you to project subconciously onto new kit, that it sounds like an MF, or if naim, it sound pratty?

hmmm...scratches chin...

 

Well, youre getting there.

Its 1/sqrt2 x 28voltsrms so its

0 to 40V peak in 12.5uS

You will also notice thet the maximum slope [eg at sine =45]
is steeper than the triangle wave that you are approximating, since the sine hovers nearer the peaks for some time.

So lets say its 6V per uS. Still not much right.

but.....

If my output stages 'does' 30kHz cutoff [or as Chris mentions, is acceptably slew-rate challenged], then what happens when I feed higher then 30kHz into the inputs [say background kak from my unfiltered Densen B400 CDP, or a phono stage clipping on clicks/pops] and the output cannot follow the input?

 

You're quite right Graham. It was getting late, too much wine, etc. :shame:

And yes the start of the sine wave is steeper than the sawtooth I was implying. I wonder how close the output of a CD player actually gets to a sine wave at 20 kHz

 

If your sources are generating maximum level outputs at 20-30kHz then you have much greater problems than slew rate limiting.

Paul

 

Quite right Paul, it was a theoretical discussion. It wasn't much help in explaining why some amps sound faster than others. Or some speakers for that matter. If it's not down to transient response then what does that leave? Phase response for one. I guess variations in the frequency response might contribute too. As might distortion of one form or another. My money's on phase

 

I'm intrigued as to what this MW radio transmitter that Graham N is using is. I'm a bit cynical about something claiming such unnecessary performance in such specific areas.

Paul

 

How many more years of your spiel to go? Just curious.

 

Paul - it's an LC Audio Patriot V100 (unfortunately no longer in production). The record of my initial orgasms over it are here. I would normally agree with you about such over-specification, but it seems to work. Avoiding the phase dispersion inherent in low-pass filters may have something to do with it - although I would have thought that anything out of the CDP would be dominant. As for the number, I suspect they just worked hard at zero-feedback, high-bandwidth stuff and 4MHz was just where they ended up. The spec on their latest stuff has dropped to 1MHz.

Only downsides at present are intermittent atmospherics-type hash from the right-hand channel - probably some capacitor on the way out, but it's been hanging in there for at least 6 months now - and low-level hum from the transformers (high enough to notice when late night smooooth stuff playing, but frequently masked by e.g. computer fan hum from the other end of the room).

(And I think you guys - TB/LCD - are being just beastly - jumping on me like that for a simple bit of willy-waving )

 

As many as I feel like James. But of course, unlike Naim, you are welcome to disagree with me without anyone banning you from a forum

 

Well, it's difficult to disagree with you because your system/tastes/opinions seem to be a continuously-moving target. For how long did you keep your longest-lasting hi-fi component? Have you ever owned any Naim components, and if so, what was/were it/they & how long did it/they last in your system? And what did you think was wrong with it?

And what about stands? The Mana/Finite whatsit. Days, weeks or months? Surely not years. And why did you sell them?

You remind me a bit of 'Dark Lord' who has owned very many turntables & stands, and who seems to get his from swapping gear about.

 

Interesting.... Looks like LC audio's claims on bandwidth are surprisingly wide.

Certainly looking at the Zappulse, they claim -3dB at 140kHz. However, the switching only occurs at 470kHz. That means that the switching noise on the output isn't more than 10dB down, assuming a second-order output filter.

 

I usually find by adding NO2 to the output stage of the B/C, the increase in speed is most noticable