Hi All,

I'm newly on this forum so be gentle!

Current system is LP12/CDi/AudiolabC+P/SD1's

I went for the the Audiolab to explore Bi-amping techniques but never bought a second P (These are UK versions).

The SD1's were specifically designed for passive bi & Tri amping giving individual access to the separate crossover sections.

I spent a long while demoing recently at a my local (Bucks dealer) store.

Combinations of 282 vs 252/Hi-Line vs S/cap (on 282) and 200 vs 250.

On paper we (that's the good woman and I) decided that 252/SC/250 was obvious choice. But in the end I selected following;

282/SC/200 as my proposed choice. The SC made a really sigDiff over the HiCap. Don't get me wrong the 252 and 250 were both flippin' good but the presentation of the music was different and (we used our own speakers for the demo) seem to balance better as a system.

Okay I am not talking heresy here, there really is a significant difference in the way the two pre-amps (and the PA's) present the sound and not everyone will prefer the 'notionally best' combinations of components. I was just more surprised than I expected to be.

We then tried the same set up but passive bi-amped with an extra 200. Wow!! I didn't believe it. The presentation of the music was the same (a presentation we preffered) but the detail exposed was much greater with more 'air around' the instruments and a vastly better controlled upper bass range.

End result was 282/SC/2X200's ordered. Of course now I can't wait to get this stuff installed!

Lots of people here will jump in & tell you its heresy to bi-amp with Naim.

If YOU like it, thats all that matters. If it makes music enjoyable for you then its good.

282/SCAP/200 X2 will im sure be a stunning combination.

You have done the only comparison that matters.

Yep thanks for that. I am certainly interested by others view and I am happy to hear them. However you are right these are my ears and I have to live with 'em so I always make my own judgements.

The combo was stunning in the demo room.

quote:

Originally posted by bon:
I am certainly interested by others view ...

Not sure why that should be .... now that you have ordered.

Sorry didn't make myself clear. I mean I am interested in others views from a philosophocal viewpoint, from the general interest. What there experiences etc.

Not from the perspective of helping me make up my mind (I can make my own mind up )

It's just interesting to hear other views, otherwise why have a forum?

My starting point was CDX2/ 282/HC/200, and it was already the best sound I had enjoyed since getting into "proper" hifi in the early 80s. In discussing the various upgrade paths available with fellow forumites and 2 different dealers bi-amping was never evn mentioned as far as I recall. Adding a 555PS was the next step and then a Supercap to replace the HC. Each of those moves made a significant improvement. A 252 and 250 were less impressive and I ended up where I am now, whch for me is the ultimate system. I think I am more likely to swap my 300 for a 500 than I am to add a second 300.

Very interesting what you found though bon. There are many routes to heaven, grasshopper!

quote:

Originally posted by bon:
We then tried the same set up but passive bi-amped with an extra 200. Wow!! I didn't believe it.

End result was 282/SC/2X200's ordered. Of course now I can't wait to get this stuff installed!

That says it all, despite the apparently heretical biamping. FWIW, my dealer is also a fan of biamping passively with Naim.

regards

Peter

Bon,

Im suprised at your findings and Im happy for you. I had a 200 for a while and pondered on getting another to passively bi-amp due to my speakers requiring more power. I understood the Naim philosophy was to go the next amp up in the chain instead and followed that path, skipping a step and going to the NAP300.

That was an utter revelation as the NAP300 is dual mono, which I guess is bi-amping. Im now building my system around the NAP300 and I may consider getting another NAP300 in the future: so one powers bass, one powers treble...

Ill have to investigate!

Jon

Consciousmess,

I thought this too and though I haven't verified this (as a 300 was out of my budget) I have a feeling this would work very well.

I am planning when funds allow adding a 3rd 200 and driving all cones with their own power channel. (The good lady agrees completely with this strategy, I am blest indeed!)

Good luck,

bon

quote:

Originally posted by Consciousmess:
...I understood the Naim philosophy was to go the next amp up in the chain instead and followed that path, skipping a step and going to the NAP300.

All sorts of Naim 'traditional philosphies' are being broken these days, like an integrated amp designed to work bi-ampable, the Supernait, which logically must cause a re-think in the philiosophy!

quote:

the NAP300 is dual mono, which I guess is bi-amping.

Dual mono is, effectively, two mono power amps side by side, one each for l & r channel, in one case.

Whereas passive biamping (triamping) gives each frequency of drive unit its own amplifier(s). [Thus for a 2-way speaker biamping - 2 stereo or 4 monoblock amps; for a 3-way speaker triamping - 3 stereo or 6 monoblock amps.] This is passive biamping (triamping) because it feeds into the passive crossover of the speaker.

Going active (only possible with certain speakers, such as Naim's own or Linn Isobariks) utilises an active (powered) crossover between the pre-amp and power amps, splitting the signal into its frequency bands first before it is boosted by the power amps. The speakers' own passive crossovers are eliminated from the equation.

In those speakers where going active is possible, a principle advantage is being able to split the frequencies at the tiny signal stage, rather than the fully powered-up signal (just compare the size of components in a typical high-end passive speaker crossover with those in a SNAXO active crossover). This greatly eliminates distortion.

James

Thanks for the clarification James as I have wondered that!

Jon

Hi James,

Yes good clarification. From a technical point of view I have some 'signal' issues with both Bi(Tri)-amping in both passive and active modes. I'll get to this later.

But beside the concerns I'll raise I will say that I have listened to both types and in theory the Active approach *should* make more sense. As you rightly say smaller signals. The speakers I have were originally designed for Tri-amping and give direct access to the crossover tap points at the terminals. I was fortunate to actually try these bi-amped with a pair of 200's at my dealer and was sufficiently impressed to buy two 200's now and probably another in a few months.

Now to the 'concerns'. The issue here is how an amplifier drives an impedance. Reason is that if an amplifier is looking into a filter (say a passive Low pass) then below the cut-off frequency the amplifier will see the impedance of the Load and the filter will only have a small amount of transmission loss (say 0.01dB) and minimal refelction (i.e. it is 'matched)

However above cut off the impedance of the load will not be seen by the amplifier and there will be significant energy reflected above the cut off frequency. Reason is that for my example a LPF will have a parallel input capacitance and series Inductive elements and at High frequencies the Capacitor is a Short circuit (i.e. all energy reflected with 180 deg phase shift). This means that outside its particular frequency band the amplifier is driving a short. As all the frequency range is still being fed in from the Preamp this means the amplifier is driving a short for about 2/3rds of it's band. The same discussion holds true for the High pass amplifier and the mid-band (Band pass) amp.

For all intents and purposes the reverse isolation of an audio amp will be extremely high (100dB or so) so there will be no obvious change on the input impedance as the frequency range changes.

This is all well and good if the amplifier is capable of driving into such loads but not all are. I haven't heard a single counter argument to these comments except that what I hear isn't the sound of unstable amps!!

A whole similar argument can be made about Active crossovers though here I am guessing that these could be more rigourously made so that they are properly terminated out of band or they are designed as Di or Tri-plexers so that the band reflected is directed down another branch. The active crossovers are also electronic and use active devices and so I would expect them to add some noise (johnson, flicker and Boltzmann) to the signal. This should be low in terms of the overall amplifier system as they come after the Pre-amp.

Okay I am speaking here as a High frequency designer (my background is Microwave Amplifier deesign) but the same principles apply and you can successfully employ the whole transmission/reflection (S-parameter) techniques to these beasties.


Still for now I am going with what my ears are telling me!

quote:

Still for now I am going with what my ears are telling me!

Head of nail hit...