There’s a lot of discussion on the forum about passive bi-amping and how Naim never used to recommend it but I was wondering if anyone has actually tried it especially with more demanding speakers? I’m thinking about upgrading to 300dr but also keeping my 250dr and bi-amping my B&W. I understand the distinction between passive and active and that active is generally better but I was wondering of people’s actual experience with passive and not just pure theory.
Been there and done that
It brings things more HIFI but the more boxes in the system lost musicality for me.
Now very happy single amp passive.
Everybody will tell you their own preference.
Taste and try before you buy. 
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Don’t discount trying , It can have benefits with “difficult” speakers .
But at the cost of sourcing cable .
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If you have speakers that have good synergy with Naim amps but simply don’t have the power for them, them passive bi-amping is certainly more cost effective than going to a Naim amp with a lot more power than the one you already have. For example, 2x250 is going to cost a lot less than a 500.
There is one thing that bears mentioning though. Passive bi-amping seems to be done different ways in different places. The way most UK manufacturers do about it was as a stepping stone to some kind of active configuration so the cables supplied make each amp still be a stereo power amp driving stereo treble or stereo bass. But that doesn’t give you much more power because a single amp is still doing most of the work.
I’ve come around to the correctness of the philosophy that Japanese makes employ for bi-amping where each amp gets a twin mono signal, either left or right. And is effectively used like a split monobloc. One channel drives treble, the other bass and the transformer only services half the load. You get significantly more power and also the return ground is for the same channel. I know you can do this with Naim amps if you ask for the right kind of interconnect to be made up.
I guess the question is, do you feel that your speakers need more control that a single amp can deliver? If the amp is not struggling to control the speakers at all, I’m not convinced of the benefit. If it is struggling, I would only do it the dual mono way. Others may disagree (probably will).
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Thanks Feeling_zen, some interesting comments. The speakers are 803d4 and as I mentioned I’m looking to get a 300dr. I’m guessing for dual mono I would need 2x250 or 2x300? Also would that be connected to supercap?
If certainly would not advise biying another amp to passovely bi-amp, but if you’re buying a 300 but not part-exchanging the 250, there s absolutely no harm in trying. You can then decide if any difference is worth the resale value of the 250. Other people’s experiences aren’t of much value unless with the same speakers.
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Naim doesn’t recommend passive bi amping. But trying doesn’t make harm.
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I tried it several years ago with an Olive case setup NAC92, flatcap, X2 NAP90. The power amps were a lowly 30W each but of course with Naim good current reserve. The extra power did help driving the bass handling but I would say overall it did not add that much in terms of musical presentation.
It wasn’t bad though and I had the setup for several years but now I have a Black box setup with a single Power amp and I am very happy with it.
I would not recommend bi-amp with different model power amps even if they are both Naim. Two of the same model is much better and the way to go if you are going to do it.
I remember years ago in the Hifi shop I was working in we tried a Class A valve amp for the tweeter and a Naim power amp fo the bass/mid. The idea was the power (Olive/chrome 250 I think) was needed for the bass but a sweet lower power valve amp would make the upper frequencies sound smooth and lovely. How wrong we were it sounded terrible. It was like listening to a tweeter out of phase with the bass/mid, just awful.
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I was pleasantly surprised when I tried biamping my speakers with two 500s. I expected better control of the bass which is generated by two large (30 cm) drivers working in opposite directions. But there was also improvement in the upper registers which were apparently not impeded by the behaviour of the bass drivers any more. All aspects of the music were just better.
A dealer will have no problem combining the two DIN-XLR cables into one DIN plug for connection to your supercap.
I learned that the better amp needs to go on the treble although the tweeter might use the least power.
However, I do not believe that bi-amping is a way to save money. You need to carefully check whether the bi-amping setup is really better than a single higher level amp. Also, bi-amping only shows its full potential when the low and high frequency branches are equipped the same way. I had to learn this the hard way when I thought I could get away with Superlumina cables on the treble and NACA5 on the bass. That was a costly mistake.
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You wluld indeed need two identical amps with similar sereial numbers. And yes, ot would require a special unusual set of interconnects made to order for the SuperCap to poweramps. So it’s not possible in this case with a 250 and 300.
You can always try the classic Naim way though. No harm and if the speakers are B&W I think that is one scenario where Naim have actually found passive bi-amping beneficial due to their difficult crossover.
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If the speakers are designed for passive biamping, ie when the crossover network for the low/mid/high have their own terminals, usually it will benefit from passive biamping (using identical power amplifiers). I’m started with a single ATC P2 to drive the JBL M9500. Slowly I added 2 more P2s and now each P2 drives a single driver passively. After a while, I tried to go back to driving the speakers with a single P2. It took me 5 seconds to switch back.
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But may well perform better with a single better power amp costing similar to the sum of the multiple… Indeed I would rather expect that to be the case, unlike active multi-amping where the benefite of an amp channel per speaker channel is so much greater.
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More usually that is simply done to allow bi- or tri-wiring rather than passive multi-amping, following the fad for it a while back, though with some speakers it is also to facilitate converting to active multi-amping, simply requiring the internal crossover, often attached to the back of the terminal plate, to be removed and instead connecting the drivers direct to the terminals.
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I tried this with a pair of OC 250s into my Wilson Benesch Vectors a number of years ago.
I then auditioned a 300DR…which I have to this day.
Usual caveats apply of course, but for me, the 300 was significantly better than the bi-amped 250s.
Cheers,
Ian
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That too, but it says clearly in the jbl manual that it’s for passive bi or tri amping.
Well, it kinda defeats the point of having the crossovers in the low power circuits (where they can do less harm).
Interesting. I wonder which if any other manufacturers say that. PMC don’t in the manuals for the two I’ve had (with triple binding posts)
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Indeed if you look at the P1 or P2, it comes with an extra connector for daisy chaining the power amps. That’s what I did.