Electronic Crossover?

ecc83

Well-known member
Wow! Robby A, rarely have I seen you 'lay into' a poster like that! I shall keep well out of the fray since my knowledge and experience on the subject is practically zilch.

The concept of "bi-amplification" as I recall it grew initially from the shortcomings of early power amplifiers? Certainly back when valves were all you had, a 100W amp was heavy, expensive chunk. The coming of the Silicon transistor eased things a bit but you still needed a pretty massive power traff.

Splitting the spectrum gave the amps an easier time (less IM distrotion) and allowed a ;lower power amp for treble. For the same total amp power you got a greater SPL. The coming of SMPSUs and much cheaper 'watts' means bi amping has maybe lost some of its advantages ?

Bi and tri amping has of course found its true home in studio monitors. The design requirements for PAs are eased considerably when Joe Public can't connect dodgy loads!

Dave.
 

rob aylestone

Well-known member
I have a friend - he used to work for me, at my level and now is a system tech on international touring for big name bands. The PA manufacturers constantly fiddle and tweak and send him new files to 'improve' the sound. He installed one ahead of a show in Germany and was very happy. When the next version arrived, he put it in and realised he had mistakenly put in last time an elderly one, and hadn't noticed. I suspect strongly that large format sound systems are so dependent on the spaces they are in that the concept of 'quality' is considerably different. If you have spent vast sums of money on integrated and coordinated systems, then not putting in what the manufactuers sends you is a bit silly. They have the test gear and systems to prove the improvement. Nobody can argue with that. However, I remain uncertain that these 'improvements' are audible. After all, when your ears hear output from multiple sources, you are always compromised. Quantative measurements can be made from simple systems where everything is controlled. With big systems in big spaces, so much time is spent tweaking to try to give as many seats as possible the same sound. I work mainly in big theatres - opera houses, that kind of thing and I quietly grin watching the sound designers wandering all over, tweaking this, tweaking that and then they go away, leaving it in the hands of the show operators. For certain shows nowadays we do a version for people who have specific needs. We call them relaxed performances. So there will be folk with varying degrees of autism, or hearing or sight issues. My role is to watch as much as I can and keep the shows exactly as the Director wanted, putting a stop to slide and shortcuts. As a result I have seen the same production from almost every place, and the sound fares worse than lighting. So I will instruct the sound op to reduce the subs in certain locations where it would be too much, perhaps reduce the top end crispness in others. I'll remove pyrotechnics and cut strobes - all for one, safe, gentle performance for people who cannot take the usual loud, bright, exciteing and sometimes deliberately shocking stuff.

Often, what I do is not at all what the various designers wanted, but for just one show, this is how it is. Many people report they did not notice the changes.

we started this topic with discussion on if it was worth bi-amping smaller boxes that have passive crossovers. I've done this myself and come to the conclusion, it rarely works unless the speakers are designed to allow this - then it does work. Some manufacturers use their own amps to drive their own speakers which is probably the best integration to ensure what comes out is what was intended to come out.

Does anybody remember those Philips motional feedback speaker systems where the speakers sent back information on what they actually did to the amp, which then modified the output to creater a closer replication of the waveform? That concept didn't last very long.

I'm just an old sceptic at heart. Few 'improvements' really jump out anymore. They tell you they're better and people believe them. On this forum, so many times, we have had people suggest products that really break the rules and work. People who have used a mic in a very unusual way, through need, and discovered it really works. Then we have others who dismiss products based on internet gossip and rumour.
Grump over - sorry.
 

Smithers XKR

Well-known member
I have a friend - he used to work for me, at my level and now is a system tech on international touring for big name bands. The PA manufacturers constantly fiddle and tweak and send him new files to 'improve' the sound. He installed one ahead of a show in Germany and was very happy. When the next version arrived, he put it in and realised he had mistakenly put in last time an elderly one, and hadn't noticed. I suspect strongly that large format sound systems are so dependent on the spaces they are in that the concept of 'quality' is considerably different. If you have spent vast sums of money on integrated and coordinated systems, then not putting in what the manufactuers sends you is a bit silly. They have the test gear and systems to prove the improvement. Nobody can argue with that. However, I remain uncertain that these 'improvements' are audible. After all, when your ears hear output from multiple sources, you are always compromised. Quantative measurements can be made from simple systems where everything is controlled. With big systems in big spaces, so much time is spent tweaking to try to give as many seats as possible the same sound. I work mainly in big theatres - opera houses, that kind of thing and I quietly grin watching the sound designers wandering all over, tweaking this, tweaking that and then they go away, leaving it in the hands of the show operators. For certain shows nowadays we do a version for people who have specific needs. We call them relaxed performances. So there will be folk with varying degrees of autism, or hearing or sight issues. My role is to watch as much as I can and keep the shows exactly as the Director wanted, putting a stop to slide and shortcuts. As a result I have seen the same production from almost every place, and the sound fares worse than lighting. So I will instruct the sound op to reduce the subs in certain locations where it would be too much, perhaps reduce the top end crispness in others. I'll remove pyrotechnics and cut strobes - all for one, safe, gentle performance for people who cannot take the usual loud, bright, exciteing and sometimes deliberately shocking stuff.

Often, what I do is not at all what the various designers wanted, but for just one show, this is how it is. Many people report they did not notice the changes.

we started this topic with discussion on if it was worth bi-amping smaller boxes that have passive crossovers. I've done this myself and come to the conclusion, it rarely works unless the speakers are designed to allow this - then it does work. Some manufacturers use their own amps to drive their own speakers which is probably the best integration to ensure what comes out is what was intended to come out.

Does anybody remember those Philips motional feedback speaker systems where the speakers sent back information on what they actually did to the amp, which then modified the output to creater a closer replication of the waveform? That concept didn't last very long.

I'm just an old sceptic at heart. Few 'improvements' really jump out anymore. They tell you they're better and people believe them. On this forum, so many times, we have had people suggest products that really break the rules and work. People who have used a mic in a very unusual way, through need, and discovered it really works. Then we have others who dismiss products based on internet gossip and rumour.
Grump over - sorry.
Rob, sorry if this sounds like a stupid and inane question... but.

I inherited a nice DOD stereo rackmount active crossover from the break up of a band as part of the share out of gear 27 years ago...I did not want the useless inefficient wardrobe size bass bins of the time πŸ˜… I screwed it into my rack but cant think of any practical use it could have in a home studio application, so it is nice but seems redundant.
Any ideas for use? I suppose I could get sub woofer to link to my studio wall monitors but then I would need the omnidirectional sub powered and with crossover outputs for the top monitor speakers and probably get evicted by the neighbours πŸ˜…
Thanks Rob πŸ˜‰πŸ‘
 

Smithers XKR

Well-known member
I have a friend - he used to work for me, at my level and now is a system tech on international touring for big name bands. The PA manufacturers constantly fiddle and tweak and send him new files to 'improve' the sound. He installed one ahead of a show in Germany and was very happy. When the next version arrived, he put it in and realised he had mistakenly put in last time an elderly one, and hadn't noticed. I suspect strongly that large format sound systems are so dependent on the spaces they are in that the concept of 'quality' is considerably different. If you have spent vast sums of money on integrated and coordinated systems, then not putting in what the manufactuers sends you is a bit silly. They have the test gear and systems to prove the improvement. Nobody can argue with that. However, I remain uncertain that these 'improvements' are audible. After all, when your ears hear output from multiple sources, you are always compromised. Quantative measurements can be made from simple systems where everything is controlled. With big systems in big spaces, so much time is spent tweaking to try to give as many seats as possible the same sound. I work mainly in big theatres - opera houses, that kind of thing and I quietly grin watching the sound designers wandering all over, tweaking this, tweaking that and then they go away, leaving it in the hands of the show operators. For certain shows nowadays we do a version for people who have specific needs. We call them relaxed performances. So there will be folk with varying degrees of autism, or hearing or sight issues. My role is to watch as much as I can and keep the shows exactly as the Director wanted, putting a stop to slide and shortcuts. As a result I have seen the same production from almost every place, and the sound fares worse than lighting. So I will instruct the sound op to reduce the subs in certain locations where it would be too much, perhaps reduce the top end crispness in others. I'll remove pyrotechnics and cut strobes - all for one, safe, gentle performance for people who cannot take the usual loud, bright, exciteing and sometimes deliberately shocking stuff.

Often, what I do is not at all what the various designers wanted, but for just one show, this is how it is. Many people report they did not notice the changes.

we started this topic with discussion on if it was worth bi-amping smaller boxes that have passive crossovers. I've done this myself and come to the conclusion, it rarely works unless the speakers are designed to allow this - then it does work. Some manufacturers use their own amps to drive their own speakers which is probably the best integration to ensure what comes out is what was intended to come out.

Does anybody remember those Philips motional feedback speaker systems where the speakers sent back information on what they actually did to the amp, which then modified the output to creater a closer replication of the waveform? That concept didn't last very long.

I'm just an old sceptic at heart. Few 'improvements' really jump out anymore. They tell you they're better and people believe them. On this forum, so many times, we have had people suggest products that really break the rules and work. People who have used a mic in a very unusual way, through need, and discovered it really works. Then we have others who dismiss products based on internet gossip and rumour.
Grump over - sorry.
Coming back to the active v passive debate, I would just like to add.... and this is MVHO....
I am not a live engineer, just a musician.
From my limited experience I think full range cabs can work ok in a small venue with a passive x-over but... they need bass bins with an active upwards of 200Hz. The passive is ok for the higher frequencies to split between a 12 and an 8 and a bullit but for the lower range I think you really need a dedicated active and the right speakers.

Just MVHO πŸ˜‰πŸ‘
 

LazerBeakShiek

200M Subscribers
I screwed it into my rack but cant think of any practical use it could have in a home studio application, so it is nice but seems redundant.
Any ideas for use? I suppose I could get sub woofer to link to my studio wall monitors but then I would need the omnidirectional sub powered and with cr
In a jam, need a subwoofer. Get a 12volt wall adapter . Bring your car stereo subwoofer inside. Hook it up. Use the 12 volt adapter to power the box. Works amazing if you got a 8-12" enclosure in your trunk.. Mine is on quick disconnects.
 

LazerBeakShiek

200M Subscribers
we started this topic with discussion on if it was worth bi-amping smaller boxes that have passive crossovers. I've done this myself and come to the conclusion, it rarely works unless the speakers are designed to allow this - then it does work. Some manufacturers use their own amps to drive their own speakers which is probably the best integration to ensure what comes out is what was intended to come out.

Bi amplification was/is awesome. You no longer used a subtractive tone control to adjust treble and bass. It was done through speaker balancing. The 10's ( and horn ) to the Hi's, and 15's to the lows. The signal never subtracted to drone up the bass this way. It works every time on my ADA bass stack with 10's and 15..
.

Cross-overs are great to split it up. The subwoofer always reproduces the basses better. So you cut the lows from the stereo monitors and X over in the subs. The monitors could handle the bass somewhat, its just the subwoofers are better at it.
 

Smithers XKR

Well-known member
In a jam, need a subwoofer. Get a 12volt wall adapter . Bring your car stereo subwoofer inside. Hook it up. Use the 12 volt adapter to power the box. Works amazing if you got a 8-12" enclosure in your trunk.. Mine is on quick disconnects.
Thanks, I think I will look for a dedicated subwoofer. You can get a 12 inch omnidirection one now that weighs about 7 pounds now and pushes out more power than the two 15 inch wardrobes weighing 100 pounds each I had to carry up staircases to do gigs in small clubs 30 years ago πŸ˜…πŸ˜…πŸ˜‰πŸ˜‰πŸ₯°πŸ₯°πŸ‘πŸ‘πŸ‘
 

Smithers XKR

Well-known member
Bi amplification was/is awesome. You no longer used a subtractive tone control to adjust treble and bass. It was done through speaker balancing. The 10's ( and horn ) to the Hi's, and 15's to the lows. The signal never subtracted to drone up the bass this way. It works every time on my ADA bass stack with 10's and 15..
.

Cross-overs are great to split it up. The subwoofer always reproduces the basses better. So you cut the lows from the stereo monitors and X over in the subs. The monitors could handle the bass somewhat, its just the subwoofers are better at it.
Totally agree, active splits it better for the low eq
 

Smithers XKR

Well-known member
Bi amplification was/is awesome. You no longer used a subtractive tone control to adjust treble and bass. It was done through speaker balancing. The 10's ( and horn ) to the Hi's, and 15's to the lows. The signal never subtracted to drone up the bass this way. It works every time on my ADA bass stack with 10's and 15..
.

Cross-overs are great to split it up. The subwoofer always reproduces the basses better. So you cut the lows from the stereo monitors and X over in the subs. The monitors could handle the bass somewhat, its just the subwoofers are better at it.
My point being that how you amplify the frequencies below 200 Hz are the most important. Get that right and all else is easier to do IMVHO. You can run the mid and high range very well above 300hZ with a good efficient digital power amp of 300W or so. IMHO. πŸ‘
 

ecc83

Well-known member
Coming back to the active v passive debate, I would just like to add.... and this is MVHO....
I am not a live engineer, just a musician.
From my limited experience I think full range cabs can work ok in a small venue with a passive x-over but... they need bass bins with an active upwards of 200Hz. The passive is ok for the higher frequencies to split between a 12 and an 8 and a bullit but for the lower range I think you really need a dedicated active and the right speakers.

Just MVHO πŸ˜‰πŸ‘
Your instincts do you credit friend. Bass, especially below about 80 Hz, needs shedloads of power which is why bi-amping was so useful. You can also get away with fairly low grade class D power amps for bass and reserve lower powered 'linear' amplifiers for the more critical mid and HF spectrum. Many active monitors go that route.

Dave.
 

Smithers XKR

Well-known member
I have a friend - he used to work for me, at my level and now is a system tech on international touring for big name bands. The PA manufacturers constantly fiddle and tweak and send him new files to 'improve' the sound. He installed one ahead of a show in Germany and was very happy. When the next version arrived, he put it in and realised he had mistakenly put in last time an elderly one, and hadn't noticed. I suspect strongly that large format sound systems are so dependent on the spaces they are in that the concept of 'quality' is considerably different. If you have spent vast sums of money on integrated and coordinated systems, then not putting in what the manufactuers sends you is a bit silly. They have the test gear and systems to prove the improvement. Nobody can argue with that. However, I remain uncertain that these 'improvements' are audible. After all, when your ears hear output from multiple sources, you are always compromised. Quantative measurements can be made from simple systems where everything is controlled. With big systems in big spaces, so much time is spent tweaking to try to give as many seats as possible the same sound. I work mainly in big theatres - opera houses, that kind of thing and I quietly grin watching the sound designers wandering all over, tweaking this, tweaking that and then they go away, leaving it in the hands of the show operators. For certain shows nowadays we do a version for people who have specific needs. We call them relaxed performances. So there will be folk with varying degrees of autism, or hearing or sight issues. My role is to watch as much as I can and keep the shows exactly as the Director wanted, putting a stop to slide and shortcuts. As a result I have seen the same production from almost every place, and the sound fares worse than lighting. So I will instruct the sound op to reduce the subs in certain locations where it would be too much, perhaps reduce the top end crispness in others. I'll remove pyrotechnics and cut strobes - all for one, safe, gentle performance for people who cannot take the usual loud, bright, exciteing and sometimes deliberately shocking stuff.

Often, what I do is not at all what the various designers wanted, but for just one show, this is how it is. Many people report they did not notice the changes.

we started this topic with discussion on if it was worth bi-amping smaller boxes that have passive crossovers. I've done this myself and come to the conclusion, it rarely works unless the speakers are designed to allow this - then it does work. Some manufacturers use their own amps to drive their own speakers which is probably the best integration to ensure what comes out is what was intended to come out.

Does anybody remember those Philips motional feedback speaker systems where the speakers sent back information on what they actually did to the amp, which then modified the output to creater a closer replication of the waveform? That concept didn't last very long.

I'm just an old sceptic at heart. Few 'improvements' really jump out anymore. They tell you they're better and people believe them. On this forum, so many times, we have had people suggest products that really break the rules and work. People who have used a mic in a very unusual way, through need, and discovered it really works. Then we have others who dismiss products based on internet gossip and rumour.
Grump over - sorry.
I think bi amping can be done, but you would have to go inside the full range cab and disconect the passive x over and rewire so not really much point, better to get dedicated speaker units and horns, bullets etc ?
 

Smithers XKR

Well-known member
Your instincts do you credit friend. Bass, especially below about 80 Hz, needs shedloads of power which is why bi-amping was so useful. You can also get away with fairly low grade class D power amps for bass and reserve lower powered 'linear' amplifiers for the more critical mid and HF spectrum. Many active monitors go that route.

Dave.
Thanks Dave, I think that amplifying the lower frequencies is the hardest part and a science in itself. As you are an engineer I am sure you can agree, thanks mate πŸ₯°πŸ˜‰πŸ‘πŸ‘
 

Smithers XKR

Well-known member
Your instincts do you credit friend. Bass, especially below about 80 Hz, needs shedloads of power which is why bi-amping was so useful. You can also get away with fairly low grade class D power amps for bass and reserve lower powered 'linear' amplifiers for the more critical mid and HF spectrum. Many active monitors go that route.

Dave.
There were a lot of "full range cabs" doing the rounds in the 80's and 90's when I was starting out. But they were not full range, they had the convenience of integrating the lower mid and higher ranges with the convenience of a simple passive capacitor based system ... but they needed a bass bin addition with an active crossover for the frequencies under 200hZ.
 

Smithers XKR

Well-known member
Your instincts do you credit friend. Bass, especially below about 80 Hz, needs shedloads of power which is why bi-amping was so useful. You can also get away with fairly low grade class D power amps for bass and reserve lower powered 'linear' amplifiers for the more critical mid and HF spectrum. Many active monitors go that route.

Dave.
In the early 90s Dave we were running a 700W system for the small venues.
I reiterate what I said earlier... the Peavey amp was one of the first digital and it was very efficient. We could run it at full tilt and there was no harmonic distortion so it was as efficient and as powerful as the previous 1k analog Amcron we previously used to run the bins and the 400w Carver we ran the top cabs.
We ran the bins setting the split eq at around 200hz using the DOD active crossover.. a great machine, the Peavey 15 bins provided a very good FR up to that level as they were an open front loaded system. The top full range cabs were 15 + 8 + bullet. The 15s in the top cabs were great for all of the low to high mid freq and the bullets were crystal clear for the time... awsome.. and the passive worked really well in those cabs. It was a great system for up to 100 seaters back in the day.
πŸ˜‰πŸ₯°πŸ‘
 

bouldersoundguy

Well-known member
Bi amplification was/is awesome. You no longer used a subtractive tone control to adjust treble and bass. It was done through speaker balancing. The 10's ( and horn ) to the Hi's, and 15's to the lows. The signal never subtracted to drone up the bass this way. It works every time on my ADA bass stack with 10's and 15..
Well, that's not something you'd want to do with a high fidelity reproduction system. When properly designed, the two speakers will have equal output at the crossover frequency, and they'll be in phase at that frequency. Filters with opposite frequency response slopes (as in a crossover) will also tend to have opposite phase response slopes. If you change the gain of one of the bandpass sections, you change the effective crossover frequency, and then the two speakers will no longer be in phase. That can cause a hole in your frequency response.
 

LazerBeakShiek

200M Subscribers
Well, that's not something you'd want to do with a high fidelity reproduction system. When properly designed, the two speakers will have equal output at the crossover frequency, and they'll be in phase at that frequency. Filters with opposite frequency response slopes (as in a crossover) will also tend to have opposite phase response slopes.
[perhaps
If you change the gain of one of the bandpass sections, you change the effective crossover frequency,
Whoa there. Hmmm. I disagree. The amplifier crossover selects what point the signal splits , going to the hi side or low side. The amplitude of those cabinets is not the same as crossover point.
and then the two speakers will no longer be in phase. That can cause a hole in your frequency response.
Biamplification works best with power section giving 60/40 ratio Low side/ Hi side. You want a little more power for the 15s. Balances the loudness better from each cabinet.
 

ecc83

Well-known member
"If you change the gain of one of the bandpass sections, you change the effective crossover frequency, "

Yes, the frequency of a filter is defined as that where the response has dropped by 3dB ref the flat portion. Increase the gain and the turnover f is no longer 3dB down at that point and will have moved to another frequency.

I am not nearly in the same league as you guys here but even I know that. "Filters 101". I can draw you a diagram if you like...DOH!

Dave.
 

bouldersoundguy

Well-known member
Well, the turnover frequency doesn't change with gain, but the crossover point is the frequency where gain is equal in the two bands, which is not necessarily the filter turnover frequency. Yes, a diagram is helpful, even a crude on like the one below. If the crossover is well designed with phase alignment at frequency a, it will almost certainly not be phase aligned at frequency b. And it doesn't take very much because the phase of the two filters is sloping in opposite directions. All that said, most people probably won't notice much of an effect outside of a critical listening environment. This kind of detail won't matter with a guitar stack or in a noisy bar.

Crossover frequency changes with gain.png
 

drtechno

Member
I believe I already know the answer to this, but I thought I'd get a sanity check.

If I am stuck working with a venue's wound system that only has 2 "2-way" speakers (Peavey PV 112 speakers), is there any point in using an electronic crossover to help divide up the high frequencies and low frequencies? The specs for these speakers says: "Heavy duty crossover network for driver protection and EQ."

So I'm guessing the speaker already does the job. I just thought I remember something form the mists of my memory that sound could be improved with an electronic crossover? I don't really see how since the tweeter and woofer are both in the same speaker. Hence my question.

Thanks!
A electronic crossover is good for adding a sub or converting the main into a bi-amp system but that's about it. Now there is crossovers that do other functions, like a DBX driverack that can calibrate equalization with a calibration mic. There is little to gain converting a main into a biamp system. I can see it being more applicable to monitors since passive crossovers have a lot of phase shifts that can cause monitoring issues that wouldn't be there if it was biamped.
 
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