Passive bi-amping with a mix of amps ?

Wish I could afford 3 Naps, Enjoy, if you get a minute, a nice read! Nap 250DR

https://www.naimaudio.com/site...20NAP%20250%20DR.pdf

rjstaines posted:

My thanks to all for your thoughts & experience and to Allante93 especially for planting the seed of bi-amping in my head earlier in the week!

Those wondering about active 802 Diamonds - B&W don't offer you a way inside unless you're willing to take a drill and jigsaw to the rear cabinet of a £12,500 speaker pair (and they're 12 months new!)... and that was never an option I considered. The other consideration is the availability of a matched crossover (which B&W don't do)... and the £cost thereof if they did.

So, no... it has to be passive bi-amping with 802's.

Now, for those who advocate the more powerful amp on the bass driver... no, no.. forget that !!  The place you need the added control and transient power that the 500 delivers over the 300, is right at your mid / high range drivers, so the 300 would connect to the lower pair of terminals & the 500 to the upper ones.

And to Tobyjug for his suggestion of vertical vs horizontal bi-amping (see post a few above), the thought is intriguing... but would you try it on a fairly new 500 and likewise 802's if you were a pensioner struggling to keep food on the table and heat the humble abode ?  (you'll note I have my priorities firmly placed... hifi, food, heating bills... in that order)   If you do give it a whirl and still have working amplifiers and speaker drivers afterwards, will you report back to us on how it sounds?  Thanks.

Roger  

 

Sounds like good reasons Roger  ;-)  DIY joinery on a 802 can't be the way to go !  More like butchery ;-)

I suppose I was thinking in terms of just plonking a Snaxo (+ eg HC) in front of your 2 amps, and leaving it at that.  But there's still those 2 boxes and then there are extra cabling considerations. 

Whether this "simple" active approach really works properly, I don't know either.  The speakers internal crossover(s) will of course remain, but in theory (if you set the Snaxo crossover at the same frequency as the "first" crossover in the 802, ie the one "between" the binding post pairs), then there should be no signal actually being filtered by that internal crossover.  Whilst the amps should have an easier job, as they're working on a limited frequency range.  I think.  But a dealer or Naim tech dept could surely advise better......

Either way, passive is obviously going to be cheaper, and that seems to rest on whether the +1 gain difference is a show stopper or not.  The suggestion is that it may well be, but if there's a way you can do the experiment without any financial commitment, I still think its worth trying - so you can hear for yourself.

Interesting thread anyhow.

Posted by KARLOSTT:

"Whether this "simple" active approach really works properly, I don't know either.  The speakers internal crossover(s) will of course remain, but in theory (if you set the Snaxo crossover at the same frequency as the "first" crossover in the 802, ie the one "between" the binding post pairs), then there should be no signal actually being filtered by that internal crossover.  Whilst the amps should have an easier job, as they're working on a limited frequency range.  I think.  But a dealer or Naim tech dept could surely advise better......"

Karlostt, the picture of the XO, which I posted is the Internal XO. With the Briks there were two Models. Isobarik's DMS & PMS. 

"The Linn Isobarik, nicknamed "Bariks" or "Briks", is a loudspeaker designed and manufactured by Linn. The Isobarik is known for both its reproduction of low bass frequencies and being very demanding on amplifiers.

Launched in 1973, the Isobarik DMS, Linn's maiden and flagship loudspeaker was based on and named for the isobaric loading principal in the 1950s. The speaker exists also as the Isobarik PMS – destined for the professional market. Although discontinued in 1992, it remains popular among audiophiles."

Mine is the latter, In Active Mode it is rendered useless, and replaced with another Black Box, an external XO,  the Snaxo 362.

With the Domestic Monitoring System (DMS), butchering was required. However, with PMS Briks, just disconnect Speaker Cable from XO, and connect directly to Drivers, located FIRMLY In place within the Briks! 

Hence, no back presure caused by internal XO. Note, even the most expensive Speakers on Market, that encompass an internal XO will produce Phase Distortion!

I call it back presure, PV=NRT, that's right a direct relationship between pressure and tempeture! HEAT!!!

Anyhow, enjoy your gear!

The Armchair QB!!!!

Allante, I think you're saying Roger needs to keep it passive  ;-)  Fair enough, as this delves too deep into the dark recesses of speaker boxes, and their design, for me to comment with any real assurance....

RJ, the suggestion (at least from my part) was to use the highest powered amp on low end WHEN you have similar quality amps! please read carefully!

if similar quality amps are used, and one is more powerful, then put it on the woofers...

but this is a tricky thing, since almost no manufacturer produces the same power amplifier with 2 versions of power... or Naim certainly does not. i just made an example of 2 generations of the same level, 182 and 200, and thinking the 200 has extra power, should be used on lows...

so, to be coherent and hear the speaker as close to manufacturer's goals, i think one should use the exact model for all drivers, no matter if active or passive. and if the sum is near or greater than the next step amp, then skip multi amping and use one better amp instead.

multiamping makes sense only in active config - if speaker allows it, or in passive if the amount of the amps used is lower then the next level of power amp's price.

while in Naim ladder usually the next step power amp is around twice the price of the one below it (250 - 2 x 200, 300 - 2 x 250 a.s.o.), results that, for the passive method, no real life gain is to be considered... that one has 2 Naim power amps in the house and wants to experiment - that's an entirely different matter.

but if 500 has 30dB gain (300 having 29 as all other Naim amps) i would certainly do not use the passive biamping! hifi and hiend means as low as possible correction through the audio chain. if one has such massive priced amps like 500 and 300 and "trumps" the frequency response of a - probably - similar priced speaker, then the whole hifi point is rather shaking!

on the other hand, the environment where the speaker plays can have more than 1dB gain or attenuation on certain frequencies... so... the experiment will beat the theory!

200% agree, I bet they sound great @ 18K a pair in passive mode with a 552 and 500 to boot, not to mention SL Speaker Cable!

Ok!!!!  We are on the same track!!!

Active Xovers with passive speakers sounds like a recipe for disaster. Even setting the SNAXO correctly won't cause the Xover in the speakers to do nothing (as has been suggested). A passive Xover is an electrical device powered by the signal feeding it. The signal will still pass through the filter and may still get split to accomodate drive unit rolloff.

You're now needlessly putting the signal through 2 Xovers instead of one.

Roger, these are thoughts rather than practical experience.... If it were me, I'd be getting the 552 and 500 DRed rather than adding a 300, and getting the SL din to xlr if you don't already have it. It's always been my understanding that passive biamps need to be exactly the same for optimum results. The sound signature of the 300 and 500 are quite different, as well as the gain, so it doesn't bode well. Added to that, you'll have the dilemma of which amp to use on the treble and which on the bass, which is something you could do without, I'm sure. So I'd say that as you can't afford another 500, forget it. You know it makes sense. 

Hungryhalibut posted:

Roger, these are thoughts rather than practical experience.... If it were me, I'd be getting the 552 and 500 DRed rather than adding a 300, and getting the SL din to xlr if you don't already have it. It's always been my understanding that passive biamps need to be exactly the same for optimum results. The sound signature of the 300 and 500 are quite different, as well as the gain, so it doesn't bode well. Added to that, you'll have the dilemma of which amp to use on the treble and which on the bass, which is something you could do without, I'm sure. So I'd say that as you can't afford another 500, forget it. You know it makes sense. 

I hate to say it, but I agree!

I thought the 802's could be used in Active mode as well as passive mode!

Overtures 800/600, DBL's, NBL's, SBL's, Briks, ....

 HH, can you add to list?  if the list is correct!

Maybe Focal is working on a home version Active Speaker System this very moment!

Feeling_zen and HH are correct, if you ask me! passive crossovers if not removed will still filter signal... and will still present the main passive filter's achille's heel: the power loss (caused by the resitive ladder used for equalize the sensitivity of the drivers)... and better use passive with same power amps. if not, better use just one, the best you can afford!

Allante93 posted:

Hungryhalibut posted:

Roger, these are thoughts rather than practical experience.... If it were me, I'd be getting the 552 and 500 DRed rather than adding a 300, and getting the SL din to xlr if you don't already have it. It's always been my understanding that passive biamps need to be exactly the same for optimum results. The sound signature of the 300 and 500 are quite different, as well as the gain, so it doesn't bode well. Added to that, you'll have the dilemma of which amp to use on the treble and which on the bass, which is something you could do without, I'm sure. So I'd say that as you can't afford another 500, forget it. You know it makes sense. 

I hate to say it, but I agree!

I thought the 802's could be used in Active mode as well as passive mode!

Overtures 800/600, DBL's, NBL's, SBL's, Briks, ....

 HH, can you add to list?  if the list is correct!

Maybe Focal is working on a home version Active Speaker System this very moment!

 

 

Any 90's era Linn loudspeaker.

For new stuff, the PMC SE range has Active as an option for most of them. Pretty darn pricey though and they are probably going to need 500s to get moving. And there are other Active ranges out there if you care to search.

Plus, if you are not concerned with re-sale value, I have known at least one instance where a customer had the Xover removed from a passive pair of speakers they would not part with and resoldered the drive units directly to the binding posts and went active that way. You need to be very sure though.

Hungryhalibut posted:

Roger, these are thoughts rather than practical experience.... If it were me, I'd be getting the 552 and 500 DRed rather than adding a 300, and getting the SL din to xlr if you don't already have it. It's always been my understanding that passive biamps need to be exactly the same for optimum results. The sound signature of the 300 and 500 are quite different, as well as the gain, so it doesn't bode well. Added to that, you'll have the dilemma of which amp to use on the treble and which on the bass, which is something you could do without, I'm sure. So I'd say that as you can't afford another 500, forget it. You know it makes sense. 

Funny you should say that HH, I was lying awake last night wondering if I should do almost what you're suggesting... 552 DR + S/L din to XLR.  I wasn't thinking of DR'ing the 500 though, mainly because I haven't heard what the cost will be.

Great minds think alike..... I'm sure I read somewhere that DRing the 500 would be about £4,000. It sounds a lot, but assuming that the difference is at least as great as that between the 250.2 and the 250DR, I'd say it's well worth it in the context of your setup. As you're no doubt already thinking, you could do the 552DR now, along with the SL xlr, and then do the 500 later if you fancied it. Given that scenario, and on further reflection, I'd definitely give the 300 idea a miss. 

All things considered, the alternative suggestions for upgrades (ie those other than bi-amping, eg DR'ing) sound a safer bet, especially if the 300 is not just "lying around".....  :-)

catalinmetal posted:

Feeling_zen and HH are correct, if you ask me! passive crossovers if not removed will still filter signal... and will still present the main passive filter's achille's heel: the power loss (caused by the resitive ladder used for equalize the sensitivity of the drivers)... and better use passive with same power amps. if not, better use just one, the best you can afford!

 

Combining active and passive bi-amping will not subject the speaker's filter components  to the same energy input as single-amping, as the energy to the tweeter's side of the speaker crossover will contain very little bass rather than the full bass energy, and vice versa for the woofer side. However the response of the speakers a little each side of the crossover point will definitely be affected, probably quite audibly:

If both crossovers gave 100% cutoff of the frequencies above/below respectively the crossover frequency, then there would be nothing in the signal from the power amp for the speaker crossover to interact with, however that is not the case, and crossovers always have a roll-off slope, typically somewhere between 6 and 24 dBper octave.  This means that the signal through the amp would contain some signal above/below the crossover frequency for woofer/tweeter path respectively  which will then be reduced further by the speaker's filt components.

So if the speaker's roll-off is 12 dB per octave, that is the normal to which the whole speaker has been designed, giving as near flat a response overall and minimising unwanted peaks or troughs. But if the signal to it from the amp was also cut off by 12 dB per octave, it would result in an overall 24 dB per octave crossover slope, which will change the character of the sound. The steeper the speaker's crossover roll-off and the gentler the active roll-off the less it might be evident - and the more the speaker's crossover is required to work.

Definitely doesn't sound a desirable thing to do.

I've just got back from my dealer who's lent me a used NAP300 (& another S/L of course).  Discussion with him, and also his confirmation with the guys at Naim, suggests the way to go would be to bi-amp with two NAP300 DRs.  It's his contention that the DR'd version of the 300 approaches the non-DR 500, albeit the sonic signature of the two amps is very different (as earlier posts have pointed out and even cautioned against).

His 300DR dem model will be available in a couple of days, so I shall start with the 500/300 option then borrow the dem 300DR and slot it in in place of the 500, giving me a good feel for how two 300's will perform.

I'm remembering a conversation with one of the very helpful Naim chaps who frequently answers technical questions on this forum, who said to me that the 500 was an exciting amp, whereas the 300 was more of a homely amp... using the analogy of a mistress vs a wife.   Since I cannot recall what a mistress feels like, the analogy has lefty me wondering for the last couple of years... perhaps I'm about to discover this

I look forward to being able to share my experiences !!

Roger 

One other thing my dealer shared with me is that the design of the B&W crossover is such that it makes good use of bi-amping, which explains why the B&W manual emphasises the advantage.  Interesting to know.

Passive biamping is a really dumb idea 

you end up with all the cost and hassle of multiple amps multiple cables. But you keep the grotty crossovers in place so you don't get anything like the improvement you would get from proper active. 

All the downsides and none of the upside. 

jon honeyball posted:

Passive biamping is a really dumb idea 

you end up with all the cost and hassle of multiple amps multiple cables. But you keep the grotty crossovers in place so you don't get anything like the improvement you would get from proper active. 

All the downsides and none of the upside. 

Agree. Ime totally dismantles the music.

G

GraemeH posted:

jon honeyball posted:

Passive biamping is a really dumb idea 

you end up with all the cost and hassle of multiple amps multiple cables. But you keep the grotty crossovers in place so you don't get anything like the improvement you would get from proper active. 

All the downsides and none of the upside. 

Agree. Ime totally dismantles the music.

G

"The benefits of an Active Sysrem are obvious, so what are the drawbacks?

Cost is the obvious first one. Given that other considerations such as better amplifiers, sources, etc could improve your system more, this tends to be an end step and therefore at the more expensive end with higher level power amplifiers. One really good power amplifier will sound better than two poorer ones!

Second is the expertise at the manufacturer. To do active properly a company has to be controlling both loudspeakers and amplifiers at a high performance level. There are very few manufacturers that are successful in both markets. 

Currently I think that only Linn and Naim promote active technology in the domestic hifi market, although it is common in pa/concert rigs. It will be interesting to watch developments as to whether the Focal/Naim merger leads to more or less active systems?

This very specialised expertise means that in practice few people will ever own an active system, even thought the rewards are great.

It’s just a shame that the pockets have to be as deep!"

{Naim's upgrade path towards an Active Systems, Allows it's PS's to accommodate multiple amps i.e. of it's  outputs, until one is ready for a full blown Active System}

That's Life!  

I think the advantages of greater control of the speaker cones and filtering at low level give rather, more benefit than just suggested, and at some cost point might beat a better amp - though the active XO does need to be set up by the speaker manufacturer to get it completely right.

ATC And PMC are other key players here - so maybe some serious listening to be done, for those lucky enough to have access to suitable dealers.

Yes.. Try one amp with black to treble and red to bass on one speaker and the other amp with red to treble and black to bass on the other speaker ( with jumpers in place ) that way the transformers has not such a difficult load to deal with ( only if all 4 channels are equal ).

Thought I'd post what the B&W manual says (after all, if they don't know what's good for their speakers nobody else will... will they?)...

Bi-wiring separates the signal paths to each section of the speaker and can improve both stereo imaging and detail resolution. It also enables the use of different types of cable for each frequency band.

Bi-amplification goes a stage further and involves the use of two independent power amplifier channels for each speaker. This is not the same as a fully “active” drive as the speaker's internal passive crossover is still used. If bi-amplification is employed, ensure that each amplifier channel has the same gain, otherwise the speaker’s tonal balance will be distorted.

Bear in mind that, even though midrange and, even more so, tweeter drivers can (and only need to) handle less continuous power than bass drivers, the amplifier feeding them needs to have an adequate voltage swing in order to supply the short-term high-frequency peaks in music without distortion. A high voltage capability implies high power, so it is not particularly desirable to have a lower powered amplifier feeding the midrange and tweeter than is used for bass drivers.

I'm guessing that Jon  "Passive biamping is a really dumb idea "  (a few posts above)  isn't a member of B&W's strategic direction think tank       I can see your reasoning Jon, but isn't it a bit like the scepticism we saw a few years (decades?) ago about what effect interconnects had on the music ?  The next couple of days will either convince me or not!  and if you live anywhere near Chester, Jon, you're welcome to come and listen for yourself   

So yes ... It is recommended to NOT use passive bi- amping with a mix of amps " so what was the point of your post ?

TOBYJUG posted:

Yes.. Try one amp with black to treble and red to bass on one speaker and the other amp with red to treble and black to bass on the other speaker ( with jumpers in place ) that way the transformers has not such a difficult load to deal with ( only if all 4 channels are equal ).

I'm going to pass with your suggestion right now, Tobyjug.  but as I said earlier, please do get back here and let us know about how it was when you gave it a try 

PS - just checking the "accidental damage" section of my house insurance to see if speaker wiring mishaps are covered... don't think they are (it's not 'accidental').