It was a bit tongue in cheek really and just to make some laugh.
I know the dcs dacs aren’t cheap but at the same time it could also be much cheaper than a naim streamer and pre amp. All depends on which model or models you are looking at doesn’t it.
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Whilst I agree with the first part, I think a 552 plus Dave may cost more than DCS Rossini Apex and no pre…
I was thinking more along the lines of the older preamps which are affordable to some extent
Bartok with apex is not much more expensive than 332 with 333. I suspect which one is preferred would be very much down to what style of presentation you prefer. For me that would probably be the Naim but I have not done a direct comparison and only heard the original bartok at home.
As i have always said we all need to try different things and see how it goes.
The Bartok has certainly changed a lot since it’s launched, new software on the ring dac, the same as the rossini now plus Apex like the rest.
Is this so? I wonder if you have any examples. It strikes me as slightly odd since one would normally be more concerned about noise at a pre input than with a power amp. The only sub 10k power amp input I know of were the B&O IcePower amps which were ~8k, so not really very low.I’d love to hear of people getting away with lower impedances, though. Aside from Phono, I thought pre-amp inputs had moved away from 47k and were generally down at 10k now (which, FWIW, still doesn’t strike me as low enough).
Not sure how to answer that as it’s basic electronics…
This might help the dynamics of load matching from the sink perspective.
And impedance bridging which is used in designing interfaces between sources and preamps, preamps to poweramps etc
Where the impedance varies with frequency of course depending on the interface characteristics between the the two devices…
Hence the value of matching between source and sink… or in ideal world or a transmission line where the impedance is constant across a frequency range… in the real world it isn’t , just like a loudspeaker impedance… what is quoted is a nominal or average impedance across the audio band.
And yes any electronic stage, especially an active stage will add its own distortion and noise… hence the importance of design to manage all these considerations.
And yes where one is doing approximate matching, which is how it’s done in hifi, you want to have the input impedance of the preamp as high as you can with respect the source output impedance…without incurring other issues such as as RFI, environmental noise etc. as per the description of impedance bridging.
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Which I think is what happens when feeding many, maybe most, power amps direct…
Though poweramps such as Naim poweramps tend to have lower input impedances than their NAC inputs.
However that in itself I suggest is not so crucial compared to the matched impedance bridging across the audio band between source output and sink input… remember the impedance is for a given frequency… and in the world of hifi small changes here can give noticeable differences in sound quality perception. It is this aspect that can result in a performance that is ideal for some and objectionable for others…
It would be interesting to see how pre and power amp input impedances vary over the audio band - unlike speakers I’ve never seen plots or data.
But similar order of magnitude, far greater than Dave’s output impedance (I don’t know about others like DCS)
Yes it will typically be a lot smoother than a loudspeaker with multiple drivers and crossovers… which I suggest is one reason why impedance bridging tends to work… albeit taste determines the optimum matching response between differing products.
That wasn’t really the question I asked. You said that pre-amp input impedances were higher by a factor of 3 than power amp input impedances. I don’t know that to be the case, and even in the Naim range I think we’re looking at 10k for the pre amps and about 18k (or 22k, depending on how you look at it). I was wondering if you had any examples with your 3:1 ratio. Thanks for the electronics lesson, though it might be worth noting that output to input ratios tend to be about 1:200, though some are even more adventurous. I was surprised to see a Meridian Pre with 47R on its outputs and Bruno Putzeys is even more daring (and confident of his cable?) with 22R, giving a ratio knocking on 1:500 into 10k! Incidentally, Thevenin would be an easier visualisation than Norton here.
What I was really hoping for was some examples of the input resistances on power amps creeping downward to around the 2k2 level or lower, since that’s what most op amps can drive. And I’m now wondering if you have any examples of what you’re calling “approximate matching”, which I don’t think I’ve seen on domestic kit.
Oh I see, yes looked at Naim’s specs online for a few models.
So an example NAIT 50 preamp input 47kOhm, the NAP200 is 18kohm for example. Hopefully that makes sense… but I don’t have any graphs of impedance vs frequency.
Simon
They are as near as dammit perfectly resistive in the audio band. The impedance will rise at the bottom end with the DC blocking capacitor and may fall at the top (circa 70k) if there’s a band limiting RC filter included on the input. In general, and especially so if going into an op amp, the impedance is defined by the resistor to ground.
I didn’t realise they were still doing 47k inputs and thought they had normalised on 10k some time ago. I can imagine anything that has to interface with legacy kit would stay at 47k but that’s a pretty outdated input impedance on most fronts - save phonos where the MM needs it for a flat response.
Heard Vitus RI-101 mk 2 yesterday. Amazing. Getting for home demo at the weekend
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Really awful?
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lol, that was genuinely the thought that entered my mind when I read that as well. But there is a chance it could sound really good as well…
But to be fair the input of the Pass Lab X30.8 has a input nominal impedance pretty similar to a Naim NAC, so will likely look like in some ways like a preamp to many Naim and non Naim sources as it appears to have a preamp stage built in.