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active crossovers vs passive crossovers - sound quality?

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Hi All,

Has anyone any experience of using a "professional" active crossover in a hifi setup? E.g. one of the dbx units as per the weblink.

http://dbxpro.com/en-US/products/223s

These are as cheap as chips (£100+) and would help to not only fine tune the right crossover frequencies when building new speakers, but could also be a permanent fixture in between pre-amp and power amps in one's hifi. My concern is that they will destroy the sound quality (in the same way as some would say a graphic equaliser would), vs a well designed passive crossover with good quality capacitors etc.

Any thoughts / experience?

Cheers.

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Super Wammer

I'm pretty sure that the Behringer unit(s), used by Serge of this parish, fall into this category and his system sounded superb to me when he exhibited it at the Wam show. I wouldn't be surprised if he comes along to answer your question - he's very helpful like that.

Hi All,

Has anyone any experience of using a "professional" active crossover in a hifi setup? E.g. one of the dbx units as per the weblink.

http://dbxpro.com/en-US/products/223s

These are as cheap as chips (£100+) and would help to not only fine tune the right crossover frequencies when building new speakers, but could also be a permanent fixture in between pre-amp and power amps in one's hifi. My concern is that they will destroy the sound quality (in the same way as some would say a graphic equaliser would), vs a well designed passive crossover with good quality capacitors etc.

Any thoughts / experience?

Cheers.

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Much better still are the DSP crossovers/eqs from minidsp ... From $105 for the 2x4

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Super Wammer

Yep, if you only need 2-way, the MiniDSP 2x4 board is excellent, so easy to change settings on the fly. MiniDSP do other boards for more inputs/outputs although they are over £100.

You can also get the MiniDSP UMIK USB Microphone, and import directly into the MiniDSP software for easy room correction/integration, and room/speaker measurement with REW.

I use a similar board in my MiniDSP PWR-ICE125 boards in my current active speakers.

Active crossovers have the potential to be better than passive crossovers, but not always, it all depends on the implementation.

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Yes, I use the Behringer DCX2496 in my system. At Scalford this year, i was helping Lawrence (biamp2) with his system which used a pro active crossover, a BSS unit. Mine uses DSP, so can be set up very easily and setups can be put into memory and evaluated against each other. It also offers different types of filters, time alignment and a whole raft of other usefuln stuff. With a non-DSP crossover it's less flexible, but still much better than a passive crossover.

Active well done will always be better than passive well done, but the important bit is the 'well done'.

S

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Here's a couple of most excellent articles on the matter:

I'm quite lucky in that I wound up using a decent 5 channel amp for my stereo set up, meaning I already had all the amps, well matched, in one box :cool:

http://sound.westhost.com/bi-amp.htm

http://sound.westhost.com/bi-amp2.htm

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Here's a couple of most excellent articles on the matter:

I'm quite lucky in that I wound up using a decent 5 channel amp for my stereo set up, meaning I already had all the amps, well matched, in one box :cool:

http://sound.westhost.com/bi-amp.htm

http://sound.westhost.com/bi-amp2.htm

Have you disconnected the Passive Crossovers from your Kef's or are you using other speakers actively?

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Has anyone any experience of using a "professional" active crossover in a hifi setup? E.g. one of the dbx units as per the weblink.

http://dbxpro.com/en-US/products/223s

These are as cheap as chips (£100+) and would help to not only fine tune the right crossover frequencies when building new speakers, but could also be a permanent fixture in between pre-amp and power amps in one's hifi.

The problem with boxes like this is the fixed slope electrical crossovers which when combined with the drivers acoustical slopes and the bumps and slopes from the baffle is almost certain to give you something a long way from ideal. What you want to apply electrically is only the part that when added to the drivers and baffle responses gives you the crossover slopes you intend.

My concern is that they will destroy the sound quality (in the same way as some would say a graphic equaliser would), vs a well designed passive crossover with good quality capacitors etc.

A passive vs active crossover comparison is unusual in the passive crossover having no entries at all in the technical advantage column. They used to be cheaper but these days for an amplifier + speaker system they are likely to be more expensive. Marketing considerations seems to be the only reason I can see for them hanging on in the home audio field. They became obsolete in the pro audio field years ago where sound quality for the money tends to be a more heavily weighted parameter.

If you are looking to start with active crossovers then as others have suggested DSP active crossovers are significantly more flexible than analogue ones and this flexibility can be used to give a higher performing system. The Mini-DSP systems being suggested are easy to use but expensive and proprietary. A PC is an open and often zero cost alternative to get the DSP. Reasonable multichannel sound cards start at about £30 with some at £10 if you just want to get going. Second hand AV receivers are the cheapest way to get the power amplifiers but you need to take care to find suitable examples with most having grossly undersized power supplies and wimpy circuitry that cannot handle the current for a 4 ohm load. The ones to look out for seem to be some of the top of the range ones from 15 years or so ago which don't have HDMI sockets and gizmos that AV enthusiasts require these days and hence do not have much value in the market.

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... A passive vs active crossover comparison is unusual in the passive crossover having no entries at all in the technical advantage column. They used to be cheaper but these days for an amplifier + speaker system they are likely to be more expensive. Marketing considerations seems to be the only reason I can see for them hanging on in the home audio field ...

Very true, but of course marketing considerations are very often the most important considerations of all. Active crossovers require some technical expertise on the part of the end user. They also mean that, at the least, the speaker manufacturers need to provide a passive cross-over for most of their customers and direct access to the drivers themselves for the ones who want to go active. The additional parts cost money and the additional complexity might put at least some customers off (even if you say in great big letters "This feature is here, but you don't have to use it !").

VB

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Have you disconnected the Passive Crossovers from your Kef's or are you using other speakers actively?

This made me laugh. A few years ago before I knew about the audiophile phenomenon I bought some KEF speakers for the kitchen which were advertised as being suitable for active use even though I had no interest at the time. A few months later I needed to learn to use some kit at work, recalled the speakers were suitable for active crossovers and so took the kit home to have a play. I could see no way to disconnect the passive crossover and a phone call to KEF informed me that any attempt to use an active crossover would void the warranty. Like most sane people it had never occurred to me that people would want to use multiple amplifiers with a passive crossover and then label it as an active setup.

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Very true, but of course marketing considerations are very often the most important considerations of all. Active crossovers require some technical expertise on the part of the end user. They also mean that, at the least, the speaker manufacturers need to provide a passive cross-over for most of their customers and direct access to the drivers themselves for the ones who want to go active. The additional parts cost money and the additional complexity might put at least some customers off (even if you say in great big letters "This feature is here, but you don't have to use it !").

Are there examples on the market of speakers with passive crossovers that support active crossovers? Is there any demand for it from audiophiles? Clearly there is sufficient demand to use multiple amplifiers with a passive crossover that pretty much all speaker manufacturers opt to bear the extra cost in order not to lose sales. But there is still a passive crossover to protect the drivers which there wouldn't be with connections for an active crossover.

If an audiophile believed an active setup was better then buying an active speaker would be the obvious thing to do. Ditto for someone believing a passive crossover was better. A speaker with an optional passive or active crossover would probably need an external passive or active crossover adding significant expense and box clutter. Who would be attracted by such an option?

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Modded speakers present this option. With speakers like Analysis Audio and Apogee restores, you can get passive or active crossovers, and decide where you want to put your money, whether in adding amplifiers to active crossovers or to upgrading the passive crossover components to Duelunds. Crossovers are first order and in an external box so changing it with the help of a restorer/modder becomes easy.

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I am tinkering with actives and for those that have gone down that route please can you help me with the following safetly concern?

If you use separate amps for tweeters then should you continue to have a passive high pass filter between the amp and tweeter to make sure that thumps, hum, disconnection pops and other potential nasties don't get through to the (relatively) delicate voice coil from the amp after the active crossover circuit? It could have a relatively steep slope with frequency set below the active's crossover range as it is purely for safety. It seems to me it is just common sense, but then it seems to me that I would read a lot more about its inclusion if it were so; so what have I missed! :dunno:

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I have an all active Open Baffle setup with just capacitors for protection between the treble amp & ribbon tweeters. No damage in +4 years in spite of occasional pops, thumps etc. Crossovers 3100hz @ 300dB slopes, DEQX DSP

Caps_zpsd3tmpyke.jpg

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I have caps on my aurum cantus ribbons that high pass at the recommended crossover point and I set the dsp above that to suit my lug holes. I didn't on the Raal's to my cost at Scalford.

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