Would speakers be better doing away with crossovers and letting the amp deal with frequencies?

[rjbell]

Sorry if i'm sounding niave here i only have a basic grasp of speaker design. I've been reading up on diy speakers and crossovers, and something occured to me. Most modern amps have 4 channels, so why do manufacturers not have the amp split the frequencys for the tweeters and woofers then have each channnel run each driver seperately and do away with the crossovers? Or even the music source having four channels of information not just left and right.

 

[record_spot]

Or just get actives.

 

[iQ Speakers]

Not a good idea every single speaker design has different frequency requirements. It would require the amp to be software driven with all the inherent problems with that. DIY speakers though are are a very good idea.

 

[lindsayt]

If you have a woofer and a tweeter you still need a crossover. With active systems you've moved the location of the crossover from after the power amplification to before the power amplification.

For some speaker systems active produces better overall sound than passive.

For others passive produces better overall sound than active.

And most modern hi-fi amplifiers only have 2 channels. It's only the audio-visual oriented amplifers that tend to have more than 2 channels.

Single driver speakers like Lowthers or some panel speakers do not require a crossover anywhere in the system.

 

[andyjm]

Speakers have "crossovers" - low pass and high pass filters to split the incoming signal to the woofer and tweeter. High quality filters that can cope with the power levels found in speakers are expensive and difficult to build, so most manufacturers opt for very simple designs that look like they started off life as part of a washing machine (have a look at one on the web, they look like Dr Frankenstein designed them). These filters make life difficult for the amp, as they can introduce all sorts of kinks and bumps into the impedance curve - the load that the amp "sees" at different frequencies.

A far, far better solution is to split the signal prior to amplication and have one amp per speaker driver. The high and low pass filters before the amps only have to work at line level, and it is much easier to build high quality electronic filters with components you can solder to a circuit board as opposed to components you have to bolt together in a speaker enclosure.

An even better solution is to use DSP - digital signal processing. Instead of using electronics for the filters before the amps, highly sophisticated filters can be implemented in software - not just crossing over between the two speaker drivers, but correcting for speaker cabinet resonances, speaker driver non linearity, and phase mismatch between the drivers.

Put all the bits (DSP processor, dacs, power amps) in the same box as the speaker and you have a digital active speaker. Make the DSP system programmable with a link, and you could customise the performance of the speaker to the room it was being used in.

Sound like science fiction? This is how pro audio systems are now, in recording studios and in particular, large venue flying arrays that are tuned and "steered" using these techniques.

Some consumer hifi manufacturers do use these techniques, the Sonos play 1 is a good recent example, and at the high end of consumer hifi Boothroyd Stuart and Meridian have set the pace. A good primer is a white paper written by Caleb Crome who was responsible for the Squeezebox Boom. Google it and it is well worth a read.

An interesting question is if the pro market has pretty much converted to active, and if Logitech could fit a wireless card, an Ethernet system, a DSP processor, 4 speakers, 6 dacs and 6 power amps (2 were used for headphones) into a squeezebox boom for less than £200, then why is the consumer hifi market still messing around with passive speakers?

A good question indeed.

 

[record_spot]

An interesting question is if the pro market has pretty much converted to active, and if Logitech could fit a wireless card, an Ethernet system, a DSP processor, 4 speakers, 6 dacs and 6 power amps (2 were used for headphones) into a squeezebox boom for less than £200, then why is the consumer hifi market still messing around with passive speakers?

A good question indeed.

Indeed. The domestic audio market is partially responsible IMO but active designs that might pass muster in a home setting are relatively few. I made the jump recently but was aware of actives back in 2007. It's a move the domestic market needs though and the sooner the better.

 

[matt49]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

 

[andyjm]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

I agree, there can be many reasons for choosing a particular type of system.

I would question your PMC comment however, I had understood that PMC's passive range was primarily consumer, and their active range primarily pro.

 

[record_spot]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

Sure, I was in that camp too. And my Tannoys, my Missions beforehand and all the rest were excellent. But get the right actives, in the room and the result is revelatory. And I'm about as far away from your typical "night and day" type as you'll get.

 

[matt49]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

I agree, there can be many reasons for choosing a particular type of system.

I would question your PMC comment however, I had understood that PMC's passive range was primarily consumer, and their active range primarily pro.

PMC's pro range comprises a number of passive designs. Once you get up to the MB2 and BB5 models, I reckon they're almost all sold to studios.

Anyway, right now I'm very happily listening to some wonderful baroque choral music through my semi-active (or semi-passive, if you prefer) Martin Logans. *drinks*

 

[Andrewjvt]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

Can you please go into details regards the good reasons

Regards

 

[Al ears]

Or just get actives.

Or something with a full-range transducer.

 

[matt49]

Let's not forget that some speaker manufacturers manage to sell passive speakers to the pro market (e.g. Harbeth, PMC).

And as lindsayt points out, some of us, while recognising that active may be better than passive in many circumstances, still persist with passive speakers for good reasons.

Can you please go into details regards the good reasons

Regards

AFAIK practically all active speakers use class A/B or class D amps. Now you might want to use a different type of amp (e.g. valve or class A) which for reasons of heat emission can't easily be built into a speaker.

Likewise some designs of speaker don't lend themselves to having power amps built in . (Obviously I'm aware that active speakers don't have to have their amps built in, though they generally do.) E.g. panels, thin-wall designs, exotic curved designs.

If the power amps are not built in and have to be on display in their own casework, active can be more expensive than passive. (Again, obviously I'm aware that actives with built-in power amps will normally be cheaper.)

I'm sure there are other reasons that don't occur to me just now.

 

[Pedro2]

Sorry if i'm sounding niave here i only have a basic grasp of speaker design. I've been reading up on diy speakers and crossovers, and something occured to me. Most modern amps have 4 channels, so why do manufacturers not have the amp split the frequencys for the tweeters and woofers then have each channnel run each driver seperately and do away with the crossovers? Or even the music source having four channels of information not just left and right.

Although I'm no expert, I think that this is the road that Linn are taking with their 'Exakt' systems. Crossover boards sit inside the amp or even within the speaker stands. They also try to maintain the digital signal from their streamers until the end of the sound chain. WHSV reviewed here - http://www.whathifi.com/linn/akurate-exactakudorik/review and awarded 5 stars.

Not cheap, mind (tested at £17500!

)

I currently own a passive system but would love to hear a Linn DS feeding the new active ATC SCM40a. I'm sure the results would be stunning!

 

[davedotco]

The pricing of active hi-fi speakers are quite absurd, beyond any sense of reality.

Genelec make a 5 inch two way that is,

fully active,

has a digital input,

dsp to equalise both the speaker and in room response,

includes a calibrated microphone, computer interface and required software.

A full equalised system that goes as loud as you need, without noticeable compression and produces enough bass extension for many users without a sub, just add a source or digital preamp.

Cost, just about £1200, all in.

 

[John Duncan]

Genelec make a 5 inch two way

Which ones? I haven't been that impressed with the smaller (5" iirc, forget model) ones I had in the house recently but dsp and calibration might be a selling point for me.

 

[davedotco]

Genelec make a 5 inch two way

Which ones? I haven't been that impressed with the smaller (5" iirc, forget model) ones I had in the house recently but dsp and calibration might be a selling point for me.

The baby versions, the 4 inch 8320 and 5 inch 8330 , are relatively new and can be bought in a package with all the calibration hardware and software included.

http://www.genelec.com/studio-monitors/sam-studio-monitors/8330a-sam-studio-monitor

The bigger models can also use the "SAM" system, but you have to buy the calibration kit separately,

On a cautionary note, I have found the modern small Genelecs to be excellent, particularly the 030 and 040 models, the latter I consider exeptional value. However they are speakers and your mileage may, and perhaps does vary.

In anycase, this was not so much a blanket recomendation of the product, many hi-fi enthusiasts will not get on with them, more an observation as to what you can get for your money if you go down this route.

 

[Native_bon]

This is the very same reasons am going active. Too many problems of matching and balancing act with passive systems. I suppose you can get really good sound with passive system, but gets expensive very quickly.

Made my mind up for a Linn DS and active speakers few weeks ago.Right now passive makes no sense to me.

 

[rjbell]

This is really interesting stuff. I didn't realise i was talking about active crossovers. Reading further this sounds like a great project a bit further down the line. I've been reading about minidsp it looks lots of fun. I think i will build a pair of full range speakers for my first project. I know some people love them ad others do not. I've never heared any so it will be new to me.