Anybody out there replacing high-end speaker's passive crossovers with active ones?

I was sitting around thinking to myself while working on my active 3-way design "Self, why is it that virtually no speaker manufacturers offer an active crossed loudspeaker even though it is superior to passive crossovers?". I haven't found an answer to that one, but it did get me thinking about the idea of buying nice pre-built speakers and replacing the passive crossovers with something like a Behringer DCX2496. I personally am going to use a PC with KXProject drivers as my active crossover, but I was wondering if anyone had any experience replacing existing passive crossovers with active ones in pre-built speakers. Specific examples and explaination of the results (and even pictures!) would really be appreciated.
 
Yup.

http://www.diyaudio.com/forums/showthread.php?threadid=18020&highlight=

My reasoning is that on the lower end, going active is too expensive for what the market is willing to pay. On the high end, people are heavily invested in their megabuck amps, interconnects, preamps etc and may be unwilling to give them up (or multiply them by 2x or 3x) for an active design.
 
Hi,
Naim, Linn, ARC and others (in the UK) used to offer after market kits to convert their own passive speakers to active. All of them were expensive without the power amps.
I have just done what you are proposing. BehringerDCX2496 to develop an active xover with eq and various roll offs to find what works then discard this and use the numbers to build a discrete analogue xover to run the stereo system for real. Current thread for xover boards taking orders soon.
By the way this Scotsman is not as wasteful as it seems, the Behringer (2 off) gets used (permanently) to run an active surround system & sub.
 
Re: Anybody out there replacing high-end speaker's passive crossovers with active ones?

m0tion said:
I was wondering if anyone had any experience replacing existing passive crossovers with active ones in pre-built speakers. Specific examples and explaination of the results (and even pictures!) would really be appreciated.

I have a pair of Energy 22 Reference Connoisseur speakers: Floorstanding, vented 2-way, 7" proprietary poly woofer, Winston Burhoe tweeter, 1-1/4" thick cabinets, no parallel interior surfaces, slanted baffle, offset tweeter. I did some tweaks to improve the cabinet, then I replaced the dirt-cheap crossover parts with audiophile-quality parts.

Last summer a friend lent me a Marchand XM1, and I tried frequency modules for 1.5, 2.0 & 2.4kHz, LR4. The 2k XO sounded best of the bunch and I then bought a Marchand XM44-3 with the same slopes. I also bought a pair of 10" subs.

Eventually I started to get very critical of the sound of the system, it seemed to be doing everything right (ie not making any bad sounds) but musically it was boring. I tried the passive XO again, but I wasn't satisfied after hearing the potential of the active system.

Then I read the Loudspeaker Cookbook and realized that my LR4 slopes were giving me 5th and 6th-order acoustic slopes. I decided to mimic the original XO electronically, so I bought 2nd-order woofer & 3rd-order tweeter modules at 1.5kHZ. This was a huge improvement. If you're going to replace a passive with active, I suggest replicating the original slope and hinge point.

Just to finish the story, I lately replaced the original tweeters with the Usher 9950-20, and I'm thrilled with the results. That is a sweet tweeter, and it handles 1.5k, no problem.

Upgrading my old speakers was definitely worthwhile. I highly recommend this as a way to get very expensive sound on a minimal budget. There are some great cabs and drivers in these older designs.
 
Re: Re: Anybody out there replacing high-end speaker's passive crossovers with active ones?

audiobomber said:

I lately replaced the original tweeters with the Usher 9950-20, and I'm thrilled with the results. That is a sweet tweeter, and it handles 1.5k, no problem.

I take the above back. They're distorting badly at 1.5k, third-order Butterworth. I'm now using LR4 at 2k, which doesn't make me happy. I may try BW3 at 2K, but I'll probably have to change the woofer too.
 
chris ma said:
Yeah, Meridian has gone active in the early 80s

Meridian crossovers are beyond the conventional definition of active - they are digital. A DSP splits the input signal into the various frequency bands followed by one DAC and one power amp for each band. In the case of the four-way DSP8000 speakers this leads to eight DACs and eight power amps for stereo.
 
When you take out the passive crossover components, you change the alignment of the whole system. So when changing from passive to active crossovers, you may need to change the volume of the cabinet. This is more true with vented designs than selaed boxes which are unlikely to require any changes.

When I changed from passive to active crossovers on my own (vented) speakers, I had to increase the cabinet volume from 27 litres to 33 litres for best performance.

The bottom line with vented designs is that it may not be as easy as just swapping the crossovers over if you want optimal performance! :att'n:
 
Hi Nuuk,
could you talk us through that change in alignment going active from passive in some more detail?
Is it due to reduced resistance in series with the bass unit? which has a direct effect on Qts. or am I up the wrong tree?

That's pretty much it! It's actually the removal of the series bass inductor that causes the change in alignment.

With sealed enclosures, the effect is to reduce the Qtc producing more of a Bessel roll-off than a Butterworth. This can result in tighter but less bass. If the system Qtc is made bigger (>0.8) then the bass quality can be improved.

With vented enclosures both the port and cabinet will need changing (usually the volume needs to be increased).

So the moral is (and answer to the question posed by the thread) is that it probably won't produce best results by simply swapping the passive crossovers for active ones in the same enclosures.
 
Nuuk said:


That's pretty much it! It's actually the removal of the series bass inductor that causes the change in alignment.

The DCR of the inductor in my vented speakers is 0.15 ohms. Surely that small a value could have little effect on bass alignment? I would think woofer impedances would vary by that much (<5% of woofer DCR)

Subjectively the bass improved a great deal when I replaced passive crossover with active.
 
The DCR of the inductor in my vented speakers is 0.15 ohms. Surely that small a value could have little effect on bass alignment? I would think woofer impedances would vary by that much (<5% of woofer DCR)

As with anything in this business, there is no hard and fast rule. I just wanted to explain that there could be problems if people were unaware of the potential change in alignment. How much of a change in alignment there will be will obviously depend on the value of the components in the passive crossover.

As ever, there is no substitute for actually trying something rather than relying on the theory which should be used only as a starting point!
 
Hi,
Bullock on boxes was a good read and very well explained. In here I found all the answers I needed at the time to design & build my first non kit speakers and how to correct unmatched Qts in the 2 bass drivers. Yes, just add resistor to the low Qts to match it up. The calcs are all in Bullock and again yes I could hear the difference.
Bullock in very much into the maths and his style may not suit everyone but recommended. Pity the floppy with all the calcs, speadsheets etc was not included in the purchase price.