ATC 40A WITH NAC 72

Demo of a nac.72 ?

Long out of production I'm afraid

You still need a HiCap or similar to power the 72.

However there is another problem: you'll need long cables to connect from the HiCap to the speakers, and Naim pre-amps aren't designed to drive long cables (about 3-4m maximum including the 1.2m SNAIC from the HiCap to the 72).

If you still want to go ahead, there are some ways to do this by adding resistance in the cables or using a line-driver amp.

I own a72/hcdr so no problem here.read here latly about combining 40a with 272 wanted to understad how its dono.

You just need two appropriately wired din to XLR leads. 

+1 to what huge said

Hungryhalibut posted:

You just need two appropriately wired din to XLR leads. 

HH that won't give anything to power the 72, and is only OK if the wires to the speakers are short (otherwise without resistors or a line driver, the 72 could go unstable).

Leni has a Hicap DR, so the wires run from that. It’s no different to running 40As from a 272, which works happily. 

OK, sorry missed that, there was someone else who was trying to do the same thing having sold their HiCap.

However, if the cables need to be more than about 2.5m from the HiCap to the speakers then you still need the line driver or resistors in the signal lines, not just straight cables.

Incidentally the 272's output structure is completely different to the NAC72 - the 272 is almost unconditionally stable and has a very low output impedance; the 72 certainly isn't and doesn't.

Huge posted:

OK, sorry missed that, there was someone else who was trying to do the same thing having sold their HiCap.

However, if the cables need to be more than about 2.5m from the HiCap to the speakers then you still need the line driver or resistors in the signal lines, not just straight cables.

Incidentally the 272's output structure is completely different to the NAC72 - the 272 is almost unconditionally stable and has a very low output impedance; the 72 certainly isn't and doesn't.

It would good if the FAQ section has a piece on which pre amps require line drivers those that do not 

I have a pair of ATC 40a's coming in on home trial next week. I have a 272/555 dr and I also have a 52/Supercap.

Huge wrote:

" However, if the cables need to be more than about 2.5m from the HiCap to the speakers then you still need the line driver or resistors in the signal lines, not just straight cables.

Incidentally the 272's output structure is completely different to the NAC72 - the 272 is almost unconditionally stable and has a very low output impedance; the 72 certainly isn't and doesn't. "

Does this also apply to the 52/SC ? I only need about a 6 foot pair from the Supercap to the Active 40's. I'm having a company called Redco in the USA make me up a 6 foot pair of Mogami 2549 RCA to XLR and another 6 foot pair of DIn 4 to XLR's to use with the ATC's.

So as long as I'm below 2.5 meters on the interconnects I shouldn't have to worry about using the line driver ( I'm not sure what a 'line driver' is ) or resistors in the cables ? 

I'm going to try both the 272/555 dr and 52/SC with the ATC' 40a's. First I'll hook up just the 272/555 dr to the speakers and then I'll use the 272/555 dr a source via it's line out to the 52/SC. If I like that better I may sell the 272 and get a NDX2 to use with the 555 dr ( I've just started to use Roon and love it).  

I don't have enough technical knowledge or experience of the later preamps, such as the NAC82, NAC52 and the black boxes, so I can't comment on these with longer cables (but I still wouldn't risk it myself!).

The NAC72 an earlier preamps are not designed to drive significantly capacitative loads and a number of problems may result from trying to do so.  These include: high transient distortion levels, high distortion levels at high frequencies and ultrasonic instability or oscillation, leading to blown tweeters and/or blown power amps.

The 272 uses a different type of preamp and is better with longer cables, but even here there are still limits as to how far you can go, it's just further than the older preamps.

The resistor in the preamp end of the cable limits the damaging effect of the cable capacitance at high frequency, but you need to get the right value of resistor (100Ω is often used but for very long cables or high capacitance cable types it may need to be higher) too high a resistor value will reduce HF performance.

A line driver is simply an amplifier (often unity gain, but sometimes designed to drive multi-drop 600Ω P.A. system lines) that is designed to drive long cables (i.e. it's designed for capacitative loads).

Magic Bus posted:

...

Does this also apply to the 52/SC ? I only need about a 6 foot pair from the Supercap to the Active 40's. I'm having a company called Redco in the USA make me up a 6 foot pair of Mogami 2549 RCA to XLR and another 6 foot pair of DIn 4 to XLR's to use with the ATC's.

... 

For single ended mono use, 2497 will give a better result than 2549.

Thanks Huge. Any reason why the Mogami 2497 would be better than the 2549 ? Is it a better electrical match or you just prefer the sound ? I see a few people using the 2549 such as Halloween Man with his Chord Hugo TT using it's RCA outputs to ATC 40 actives. I think there are a few others also using 2549.

It has better signal properties due to the dielectric and the cable configuration.

I've tried both from the 272 to the 300DR and considerably prefer the 2497
https://forums.naimaudio.com/to...onnects-272-to-300dr

The dielectric material for both 2497 and 2549 appears to be the same, foamed polyethylene. 2549 has two conductors and shield so better noise cancelling for unbalanced to balanced connections when wired as such.

I've never listened to 2497 so can't comment on sound quality. Looks to be a good choice for single ended coax type interconnect.

2497 uses a thick foamed polyethylene using a dual concentric construction that reduces the current flowing between different strands within the conductors.

2549 uses a much thinner solid crosslinked polyethylene, but has two conductors which gives common mode noise cancellation when used in a true balanced configuration.  In a mixed configuration (or pseudobalanced configuration) it doesn't cancel common mode noise (however the screen does take the externally induced currents away from the 0V conductor, which, according to my mathematical models, gives a slightly better noise performance than a fully unbalanced configuration).

I have an interconnect made of mogami 2965. Is that any good?

Sounds much better than the audioquest I had before.

I am aware of that topology, but from my models (and some limited measurement) I get about 5-20dB of common mode rejection at RF, and about 1-2db in the audio band (all dependant on the source and load).  The downside is that 2497 is a better cable than 2549 in the audio band.

You can chose between better AF performance or better RF performance - your choice.  I tested both in my system and I know which worked better for me.

You’ll need a hicap to power the 72, but no need to route the signal from the 72 to the speakers through the hicap. Conenct the ATC40’s directly to the 72.

As you’re only considering demoing the ATC40, there’s no need to consider type of cable at the moment, presumably your dealer will supply something suitable for the demo.

Personally I found Mogami to be a bit hit and miss. In some circumstances the mid boost unbalanced the sound.

For unbalanced to balanced (Hugo TT RCA out to SCM40A XRL in) I would still choose 2549 as I like the sound (accurate and no perceived brightness that I hear with silver plated copper) and, from a technical point of view, the benefit of pretty decent noise rejection outweighs any minuscule, more likely than not inaudible, loss in the audio band that all cables suffer from to some extent.

Halloween Man posted:

For unbalanced to balanced (Hugo TT RCA out to SCM40A XRL in) I would still choose 2549 as I like the sound and, from a technical point of view, the benefit of pretty decent noise rejection outweighs any minuscule, more likely than not inaudible, loss in the audio band that all cables suffer to some extent.

I've tried both...

Compared to 2549, 2497 gives much better resolution, better differentiation of instrumental timbres, clearer (more readable) vocals and a more even handed presentation of all frequencies.

Unless you have severe problems with RF emissions in your area, the better RF rejection of 2549 is likely to be of comparatively little benefit compared to the better audio characteristics of 2497 (I have an RF environment where my system shows considerable benefit from substantial RF rejection precautions, but I still find 2497 to be much superior to 2549).

fatcat posted:

 

...

Personally I found Mogami to be a bit hit and miss. In some circumstances the mid boost unbalanced the sound.

Was that 2549?  'Cause some of the other Mogami cables have quite different audio characteristics.

Well, you've compared them both and I haven't. I'm surprised there is such a large audible difference.

I actually changed to 2549 from Chord Shawline after hearing noise from a closeby mains cable was being picked up. 2549 cured the problem and music became even more listenable. I also changed to a shielded mains cable (Chord C-Power)

Huge posted:

fatcat posted:

 

...

Personally I found Mogami to be a bit hit and miss. In some circumstances the mid boost unbalanced the sound.

Was that 2549?  'Cause some of the other Mogami cables have quite different audio characteristics.

Yes it was. I think you where recommending it at the time.

I’ll give the 2497 a try in the near future, it’s so inexpensive, it’s no brainer.

I like the 2549 between some front ends and pre, but not from pre to power.

Ardbeg10y posted:

I have an interconnect made of mogami 2965. Is that any good?

Sounds much better than the audioquest I had before.

I think so, I'd make the same choice for standard RCA - RCA interconnect. High quality OFC copper conductors, copper shield, foamed pe insulation, 75Ω, and even lower capacitance than 2497.

You can buy these off the shelf so no need to get a cable custom made (2965 is just a doubled up 2964) - search for Mogami Pure Patch RCA to RCA.