Why are electronic crossovers active only?

[NBPK402]

I would like to only run 1 mono amp for a 3 way DIY speaker. The only way I can find is to use a typical passive crossover. Now if you could do it with an electronic crossover you could calibrate with REW, and make your crossover easier (and make on the fly changes), but every where I look requires multiple amps.

Why couldn't you have a speaker level in (from a mono amp), and have speaker wire outputs to the individual drivers?

The only othercway I see to do it would be a analog crossover and use Dirac in front of a mono amp.

 

[Wayne A. Pflughaupt]

Why couldn't you have a speaker level in (from a mono amp), and have speaker wire outputs to the individual drivers?

Well – that’s exactly what a passive crossover is!

Regards,
Wayne

 

[NBPK402]

Well – that’s exactly what a passive crossover is!

Regards,
Wayne

But I want it to have it have adjustable crossover settings that I can set on the fly...basically my Xilica with speaker wire inputs and speaker wire outs instead of XLR ins and outs. The passive crossovers I have seen just have inductors, caps and resistors, and every time you swap out a driver you need to change parts in the crossover instead of just opening up a software program and changing the perimeters.

 

[NBPK402]

Would making a simple passive crossover and then use my Dirac or one channel of my Xilica (1 input and 1 output...just use as a dsp), work ok?

 

[Wayne A. Pflughaupt]

No, because an electronic crossover cannot handle the high-level input signal from an amplifier. Typically, a line-level signal (what the crossover uses) is a comparatively low-level signal, just a few volts max. It's not easy to make a conversion, and perhaps someone more knowlegable can weigh in, but a 4-volt signal to the crossover from the pre-amp is not more than one or two watts - if that. The crossover can't handle a 50+ watt signal from an amplifier. It would blow the its input stage. And, it would possibly blow the amplifier as well. The amplifier is looking for something like a 4-8 ohm impedance load. The input circuit for the crossover does not have that.

You already have the Xilica. Your only option if you want to pursue this, is to go ahead and get the appropriate amplifier(s) to do what you need. The good news is that active speakers are extremely efficient. I don't remember the exact figures, but I read once that an active 3-way speaker can get the same or more SPL output with something like 25 watts per driver (i.e., 75 watts total for the system ) as a comparable passive speaker powered by 200 watts or more. The good news being, low powered amplifiers don't cost a lot.

If price seems to be a concern, a good high-quality option would be some vintage Adcom amplifiers. You can pick up their GFA-535 stereo amps for $150 on ebay. A cheaper option would be the 4-channel version of that amp, the 2535, plus one of the stereo models.

Regards,
Wayne

 

[NBPK402]

No, because an electronic crossover cannot handle the high-level input signal from an amplifier. Typically, a line-level signal (what the crossover uses) is a comparatively low-level signal, just a few volts max. It's not easy to make a conversion, and perhaps someone more knowlegable can weigh in, but a 4-volt signal to the crossover from the pre-amp is not more than one or two watts - if that. The crossover can't handle a 50+ watt signal from an amplifier. It would blow the its input stage. And, it would possibly blow the amplifier as well. The amplifier is looking for something like a 4-8 ohm impedance load. The input circuit for the crossover does not have that.

You already have the Xilica. Your only option if you want to pursue this, is to go ahead and get the appropriate amplifier(s) to do what you need. The good news is that active speakers are extremely efficient. I don't remember the exact figures, but I read once that an active 3-way speaker can get the same or more SPL output with something like 25 watts per driver (i.e., 75 watts total for the system ) as a comparable passive speaker powered by 200 watts or more. The good news being, low powered amplifiers don't cost a lot.

If price seems to be a concern, a good high-quality option would be some vintage Adcom amplifiers. You can pick up their GFA-535 stereo amps for $150 on ebay. A cheaper option would be the 4-channel version of that amp, the 2535, plus one of the stereo models.

Regards,
Wayne

I have enough Icepower amps...I was just thinking if I could use 1 amp...it would cut the electricity cost of running the amps all day by 2/3. The other option I thought of was to just make a simple crossover for 500hz, and 80hz, and then use input 1 and output 1 o n the xilica as a dsp only which would then be able to feed a mono amp and then go to the crossover. One other reason was that I could upgrade to a Purfi ot Gan amp and only need a pair of mono amps. Would this work..or would I lose audio quality vs tri-amping?

 

[Wayne A. Pflughaupt]

Kinda hard to follow that, but if you're talking about sending a speaker-level signal from the amp to the Xilica's input - see statement in my previous post about speaker-level signal to the processor input.

If the 500-80 Hz crossover is passive, that defeats the primary reason for using the Xilica, unless you only need its EQ capabilities.

Regards,
Wayne

 

[NBPK402]

Kinda hard to follow that, but if you're talking about sending a speaker-level signal from the amp to the Xilica's input - see statement in my previous post about speaker-level signal to the processor input.

If the 500-80 Hz crossover is passive, that defeats the primary reason for using the Xilica, unless you only need its EQ capabilities.

Regards,
Wayne

No in the latest comment I made I was saying I would still use the Xilica to feed the amp...just not use it for a crossover. Just use input 1 to output 1 as a dsp only. I would make a simple 3 way crossover for the speakers and run the output from my amp to the simple crossover.

I think for the time being I will just use the xilica as I have been as a crossover. I now need to try the setup as a 2 way with 2 subs or as a 3 way with the subs being integrated as the sub being the bass. The subs will still sit in the same position...with the horn on top. I am being told it would be best to run the horn subs as dedicated subs.

The dilemma is if I use the subs as seperate subs...it will not help the bottom end with my Athena stereo preamp, as it has no sub capability. The whole reason for getting the subs was to take the load off of the celestion woofers from working so hard down to 20hz.

 

[ddude003]

I would say if your horns go down to 400Hz without breaking a sweat and your subs go up to 450 or 500Hz without breaking a sweat, you might try running them as a two way... Dial in a crossover in the space where they overlap and get the timing and phase right... Isn't that what your xillca is for? No harm in trying... As long as what @Wayne A. Pflughaupt points out about source > dac > xillca > amps > speakers is gain staged correctly...

 

[NBPK402]

I would say if your horns go down to 400Hz without breaking a sweat and your subs go up to 450 or 500Hz without breaking a sweat, you might try running them as a two way... Dial in a crossover in the space where they overlap and get the timing and phase right... Isn't that what your xillca is for? No harm in trying... As long as what @Wayne A. Pflughaupt points out about source > dac > xillca > amps > speakers is gain staged correctly...

I will run REW again when I get the subs in. As farmas the gain, the amps have no level control on the Icepower modules. I mada a big goof and did not save the setting in the Xilica, and when I ran REW again, I could not get the same results. The reason I think the Cel3stions are being pushed too hard is I see the Xilica clipping indicators lighting up on bass. Originally I was down 20db @20Hz with the kappa 15c woofers and the cel3stions according to Celestion were 10db higher without any room gain vs the kappa with room gain and running 2 vs celestion spec of 1. I am thinking I am running too many settings and the Xilica is clipping...not the icepower amps.

 

[deercreekaudio]

Here is an example which combines active crossovers and equalization with Dirac Live. In this we show the miniDSP Flex Eight in an active three-way speaker system that includes stereo subwoofers.

Diagram 1. Active three-way stereo system with subwoofers


We will create a four-way crossover beginning with the tweeter and then progressing through mid-range, woofer and subwoofer. The diagram below shows how to setup the routing matrix in Device Console, with the left and right tweeters on outputs 1 and 2, mid-ranges on outputs 3 and 4, woofers on outputs 5 and 6, and subwoofers on outputs 7 and 8.

Diagram 2. Crossover speaker selection and parameters are modified in the areas highlighted in red


For convenience, we will link the crossovers for the tweeters, mid-ranges and woofers as pairs. In the following diagram we link the crossover on output 1 to output 2 so the tweeters match each other. The linking function is found in the menu section of each crossover configuration page.

Diagram 3. Output channel linking function

The high-pass crossover for the tweeter in our example is a 5 kHz Butterworth 24 dB/oct filter.

Diagram 4. Crossover configuration showing cut-off frequency, filter shape and slope

The next step is to add the band pass filter for the mid-range. First we add a 5 kHz Butterworth 24 dB/oct low-pass crossover. This is a classic symmetrical mid-range to tweeter crossover example.

Diagram 5. Symmetrical mid-range to tweeter crossover

To complete the mid-range band pass filter we add a 500 Hz high-pass crossover. We now have a 500 Hz to 5 kHz Butterworth 24 dB/oct band pass filter.

Diagram 6. Mid-range band pass filter

Next we add a 50 Hz to 500 Hz band pass filter for the woofer. The reason the woofer has a high-pass crossover is because in this example the system also includes a subwoofer.

Diagram 7. Woofer band pass filter

Finally, we add a 50 Hz low-pass crossover for the subwoofer. You can now observe that the frequency duties of each driver have been somewhat equally distributed. We have chosen these crossover points because they are compatible with the operating ranges of each of the selected drivers.

Diagram 8. Completed active speaker four-way crossover

Check out the video on this topic: Crossover Basics using miniDSP Device Console

 

[Tim Hector]

If this was said already, I apologize. Essentially, an electronic crossover is in front of the amplifier, making the amplifier play only the chosen frequency range. Without the electrolytic crossover, the amp would play full range... A passive crossover is a filter network that blocks high or low frequencies after the amp. You could run both, example: you run an electronic 2 way, it may have 1 amp playing below 200 hz and a 2nd amp playing above 200, you then passively block frequencies below 3000 hz to the tweeter, you now have a 3 way crossover crossed at 200 & 3000. This may seem overly elementary for some, but I wanted to explain it simply for everyone

 

[AudiocRaver]

If I understand the OP correctly,

NBPK402: A variable-frequency passive speaker crossover would use variable capacitors and inductors, which are completely impractical at the power levels involved.

 

[NBPK402]

If I understand the OP correctly,

NBPK402: A variable-frequency passive speaker crossover would use variable capacitors and inductors, which are completely impractical at the power levels involved.

I think what I am going to try is a simple crossover and then use my Minidsp to fine tune it...that way I can get away with using a single mono block amp for each channel.

 

[LCRLive]

The whole point of active is so that each amplifier assigned to a frequency band range you feed it only interacts with one impedance load.

And light years better sounding than passive if you ask me. And how most of the audio industry, maybe 95 percent of the industry still uses passive is in my opinion surreal. It's really not that complicated to go active. It's just more times the amount of speaker wire and cables. Depending on how many bands the system is from 2-way (double the cables) or 3-way (triple cables) or more.