How to tune a crossover please?

[frustrated]

Hey guys, can anyone here me understand how to tune or setup an active crossover please? I have some basic questions I would like to ask or if anyone can refer me to an appropriate source for this would be nice, thx.

[billfitzmaurice]

Assuming you have a sub and main system you set the sub low pass between 80 and 100Hz and the mains high pass at the same frequency as the sub low pass.

[frustrated]

Thx. I got a basic understanding from this article here short while ago please a YouTube video on the subject but I still have a few questions if you guys won't mind please:

https://jlaudio.zendesk.com/hc/en-us...bile_site=true

Using the Ashly XR1001 as an example and a 2 way speaker system [sub and 2way full range speaker]

https://i.postimg.cc/fTx7rGgt/Screen...1-21-45-AM.png

Since right side is for bass, that right side's Frequency Response knob would be set at 80 and the left side which is for the Mids/Highs it's Frequency Response knob would also be also set at 80? If yes, when running in 3 way mode, which frequency setting would be used for the Mids speakers please something like 800 so then the 3 knobs would be set at 80, 800 and 1khz?

[Paul O]

The Ashly XR1001 is a 2 channel analog active crossover, so if you are using it for a typical "stereo" PA setup with left and right stacks CH1 of the crossover is for the left and CH2 is for the right.
Each channel of the crossover has 1 input and 2 outputs.. low and high.

For stereo 2-way operation first set the Mode switch to Stereo 2-way, and the Range switches on each channel in the out position so the crossovers can be set in the 40-800hz range.
Start with the Input and Output level controls at the U position, set the Crossover Frequency control to the position marked 1k(that is actually 100hz now), and the Response control to 6.
Do this for both channels.

On the back of the crossover..
The mixer main L and R outputs connect to Ch1 and CH2 inputs respectively
The Low outputs connect to the amplifier powering the subs
The High outputs connect to the amplifier power the mains.

Power everything up and play some music at a comfortable SPL, adjust the relative balance between the subs and mains with the low and high gain controls. In general we like it when the bass level is a little higher then everything else, but try to end up with these controls somewhere close tot he U positions.. +/- 30% for example

Move the Crossover Frequency control up and down just to hear the effect it has, the common sub/main crossover is in the 80-120hz range which is a bit hard to precisely set on an analog crossover like this, but because it's a logarithmic scale it will be in the range between the two tic marks either side if the 1K position.

[frustrated]

Thanks for the detailed help! I am unclear about the 3 way mode, what would be the frequency response positions for all 3 knobs please clarify whether on this or any 3 way crossover?

[Paul O]

In 3 way mode this unit is only capable of mono operation... just so you know.

The settings you use will depend on the speakers connected to each output, 80hz and 800hz could be good numbers but they could also lead to blown drivers.

What speakers are you using in this system?

[Paul O]

And note that in 3 way more there are only 2 crossover frequencies.... low - mid and mid - high.

[frustrated]

I am not referring to any particular system, just trying to understand what I am seeing in the DIY article mentioned earlier.

https://i.postimg.cc/c6G4WBwc/Screen...8-24-59-AM.png

Sorry the screenshots are not uploading directly into my posts.

So that article is showing 3 filters, my question is if I should have 3 separate speakers, one sub, one mid woofer and one horn, which frequency settings would I be using for each of the 3 frequency response knobs on any active crossover please?

[Paul O]

OK I understand your confusion now, the article describes 3 crossover filters which would be used when building a passive crossover. Analog active crossovers do it a little differently, those 3 filters are combined together in such a way that there are only 2 crossover frequencies in a 3-way setup. The upper crossover for the LOW band and the lower crossover for the MID are at the same frequency, and the upper crossover for the Mid and low crossover for the HI are at the same frequency, that is why there are only 2 frequency controls on a unit like the Ashly xr1001.

[billfitzmaurice]

if I should have 3 separate speakers, one sub, one mid woofer and one horn, which frequency settings would I be using for each of the 3 frequency response knobs on any active crossover please?

That depends on the speakers being used. The crossover between subs and mains will almost always be in the 80-100Hz range. The crossover between midbass and high frequency driver could be anywhere between 500Hz and 5kHz.

[frustrated]

OK I understand your confusion now, the article describes 3 crossover filters which would be used when building a passive crossover. .

Oops, my mistake then [sorry], thanks for clearing that up as I had thought it was referring to an active crossover.


I think I got a better handle now. I had thought that each separate speaker would require it's own frequency knob and setting so for example a 5 way setup would have required 5 frequency knobs with each having their own settings but from this screenshot I can see that in 3 way mode there are only 2 frequency knobs with each one sharing the Mids frequencies:

https://i.postimg.cc/JzYjfm8x/Screen...2-17-32-PM.png.

So this tells me guys that both frequency knows should not be set to the same exact setting, that it would depend on each speaker's frequency response requirements, is this correct please?

[Paul O]

I think I got a better handle now. I had thought that each separate speaker would require it's own frequency knob and setting so for example a 5 way setup would have required 5 frequency knobs with each having their own settings

With analog crossovers at least there are always 1 fewer crossover frequencies than speaker bands, so a 2-way speakers system has 1 crossover frequency, a 3-way has 2 crossovers, a 4-way has 3 crossovers, etc.
With a digital crossover it is often possible to set each filter individually allowing for more complex configurations.

Maybe a few definitions relative to audio applications would help.

Filter: An electronic circuit or algorithm(in the digital realm) that affects the frequency response of a signal. Filters come in many flavors, they can boost or cut a range of frequencies like an EQ control, or they can roll off or boost frequencies above or below a certain corner frequency.

Crossover: A pair of roll off filters that when ganged together produce a smooth acoustic "crossover" from one speaker driver to another.

So this tells me guys that both frequency knobs should not be set to the same exact setting, that it would depend on each speaker's frequency response requirements, is this correct please?

No they would not be set at the same frequency obviously, but it depends on more than just the speakers frequency response, driver protection and a bunch of factors that affect optimum sound quality are also a factor. For example most woofers have a published response that ranges from somewhere below 100hz up into the khz range but they are seldom used over such a wide spectrum in a speaker system, their low frequency response will be excursion limited and the cone tends to create a lot of distortion and has a narrowing output pattern at higher frequencies, so crossovers are used to limit their output to perhaps something like 80-1.5khz. Same applies to high frequency drivers, the response might extend down to 500hz or lower but they would have a very low power handling capacity and would be easily damaged if used that way so a crossover is used to limit their output to perhaps 1.5khz and above. There is also a hugh range in what classifies as a "high frequency driver" too, some can operate safely down to 500hz but others can't safely be used below 5khz so as already mentioned, everything depends on the drivers being used.

[billfitzmaurice]

Users of my horn loaded subs routinely set the low pass frequency lower than the high pass frequency of the mains What matters is the summed response of sub and main, with horn loaded subs this is usually the best way to get flat summed response, as they have higher sensitivity with increasing frequency.

I had thought it was referring to an active crossover.

Active and passive crossover do the same thing. What mainly differs is where they are in the signal chain. Active is before the amps, passive is after the amps. Active allows using a separate amp for each frequency pass band, passive uses one amp. Active allows easy manipulation of the filter frequencies and slopes, passive has fixed values.

[frustrated]

Great, making a lot of progress. Reading up on and watching videos of DB and slope settings:

The slope is the rate at which the signal rolls off or attenuates past the crossover's frequency. Slopes are set in 6 dB increments with 12 dB, 24 dB and 48 dB slopes being the most common and used in many amplifiers with variable or set crossovers. Higher end DSP tuning processors such as the TwK™ 88 and TwK™ D8 include 6 dB, 18 dB and 36 dB slopes for more advanced tuning. The higher the decibel, the steeper the slope on the crossover.

I am guessing that one can only choose the slope settings with a digital processor and not an Analog unit?

Also I am having trouble understanding how the slope or roll off translates into the sound you hear, can you guys explain this aspect for me please? Meaning if I should set a digital processor to 12db then try another setting at 48, how would that affect the sound I am hearing or what should be the difference I should pay attention to in what's coming from the speakers?

[billfitzmaurice]

Analog active crossovers have adjustable frequency but not slope. The advantage to higher slopes is better protection for high frequency devices and less pass band overlap of the driver outputs. This site explains how crossovers work very well. It speaks specifically to passives, but again, actives do the same thing, except being located before the amps they don't affect the speaker impedance. http://www.bcae1.com/xoorder.htm