OK, OK. I've got a 72/hi-cap/140 and a CD3. The new 5 series stuff is out and the 112 pre and 170 amp are right around the corner. And, of course, the 500, but that *cough* is not gonna be happening at my place anytime soon
The issue is, if I upgrade to the new stuff, say the 112 or 170 or whatever replaces the 82 and 250 (!), WHICH ORDER do I do it in? I suspect this will be an issue for many forum contributors and lurkers.
Consider:
The new stuff is reputed to be wider bandwidth, and the "old" stuff was bandwidth limited to prevent the "old" amps from oscillating. If this is so, then would I be "wrong" to replace my 72 with a higher bandwidth 112 - thus feeding a wider bandwidth signal to my 140??? Or is this not an issue???
Assuming there are no compatibility issues, like bandwidth problems, then WHICH do I replace first? And, would the 112 and 170 be a significant enough upgrade to be worth doing? I am loath, with the product line changing, to upgrade to more "old" style equipment. I could be convinced if the 82 or 250 were bargain priced.
And I AM keeping my eyes open for a 2nd hand CDX or CDS1, so I will save you the trouble of telling me to replace the CD3 first
Oh, and the info above about bandwidth limiting and such is based on my limited understanding of things that I have gleaned from the Forum. If any is simply, well, WRONG, then please tell me so 
- GregB
Who thinks smiles do a forum make
Posted on: 14 August 2000 by Mike Hanson
I don't believe the 112/150 is enough better than the 72/140 to make it worth the upgrade cost. I'll go with Bob on this one: CDX first, then 82. After that, you may want to consider a better power-amp (if you want more volume from your system) or an XPS for your CDX (to really make it sing). Catch you later!
-=> Mike Hanson <=-
Smilies do not a forum make.
[This message was edited by Mike Hanson on MONDAY 14 August 2000 at 17:32.]
[This message was edited by Mike Hanson on MONDAY 14 August 2000 at 17:32.]
Posted on: 14 August 2000 by Steven Phee
Actually, I posted a similar reply once in the old forum. But anyway, here's a concise explaination again.
Firstly, technically-speaking the term bandwidth limited is not the correct term to use here. Bandwidth limiting is what we use for RF signals in gsm communications. What we really mean here is high-frequency limiting, and the signal is a called a low-pass signal.
It's all about internal stability. To put it simply, any amplifier would be better if the internet bandwidth was as wide as possible. The pulse response would be close to ideal. However, as an amp is a low pass system, it would exhibit low-pass characteristics, one of them being a greater phase difference as freq increases. There would come a frequency where the phase difference reaches 180deg. Now, feed this signal into the global negative feedback loop, and you'd end up with perfect conditions for oscillations.
So, either we tailor the frequency response of the amp (by means of the dominant-pole capacitor in the VA stage), or we simply filter out the high freq content in signals that would approach the freq region that causes oscillations. It seems to me Naim opted for the latter, and that's what that "suitable filter" on their preamps are for.
As to the original question posted in this thread, well, I'm sure Naim would test their new products for compatibility with their existing stuff.
cheers!
Steven
