Is there any reason why first order ACTIVE crossovers aren't used?Besides the slow rolloff that is. In my system (4-way) this isn't a problem for the sub to bass crossover.
The advantage is that they can be very simple, just using some buffers to ensure controllable input and output impedance.
Greetings, Svokke
The advantage is that they can be very simple, just using some buffers to ensure controllable input and output impedance.
Greetings, Svokke
From what ive read,1st order filters sound no better than 4th order LR.
http://www.woodartistry.com/linkwitzlab/x-sb80-3wy.htm
http://www.geocities.com/kreskovs/
http://www.woodartistry.com/linkwitzlab/x-sb80-3wy.htm
http://www.geocities.com/kreskovs/
Yes, there's no reason why you can't use 1st order active crossovers, the main benefit of which is sensitivity matching. The reason they're not so common is that 1st order filters are relatively simple in passive form, so why bother with complex active.
Also, 1st order fans tend to be purists & aren't keen on using op-amps.
Also, 1st order fans tend to be purists & aren't keen on using op-amps.
David Gatti said:
I always find that funny, little do they realise (or do but dont like to admit it) that their precious music has been sent thru hundreds of them prior to reaching our ears.
Anyway yeah there is no reason really to use 1st order especially in a bass application. You really want really steep filters on the sub to ensure that no nasties get thru from the break up subs usually suffer at around 300-500hz. Also if your going to the trouble of using active anyway, 4th order electrical filters are not much more complicated then a 1st order.
You also dont have to worry about phase issues so much at low frequencies because the wavelengths are so long.
If your speakers are suited to 1st order, you can do an acive XO very elegantly by implementing the filter in the amp -- either at the input or in between 2 stages....
In a hi-pass you just shrink the value of a coupling cap to an appropriate value, for a low pass you need to add a series R, alnong with a cap shunted to ground.
No op-amps, no extra stages.
dave
In a hi-pass you just shrink the value of a coupling cap to an appropriate value, for a low pass you need to add a series R, alnong with a cap shunted to ground.
No op-amps, no extra stages.
dave
Hi there.........Originally posted by David Gatti
Also, 1st order fans tend to be purists & aren't keen on using op-amps. Come on... that statement is a load of absolute flannel...
Not to discourage Ist order users...too much has been mentioned that 1st order isn't for hi-fi....By far, floor standing cabinets with aligned drive units can hull out way more level than silly isobarik designs...the octet cabinet design is the only solution that solves lower midrange colouration from the LF units... a real sounder despite the amount of carpentry involved. Reason for oblique angles is to dispel the cabinet radiation nodes from upper order bass /lower midrange range from the LF driver units. Particle board cabinets are notorious for mid range resonants despite bracing.. Minimum wood thickness shown is 30mm, and one set of braces is shown st at 20cms apart. The midrange and upper units is in a sep cabinet.
Using reflex loading in base is great for uniform low end response and it will bang ones guts out.
The nub....I am willing to use op amps for active crossovers but everyone says that that my trumpet sound is better direct from tube amp with 1st order xover....so why complicate matters ? The other point is that tube amps don't burn up LS systems as SS amp do. I'm a fan where tube amps sound better with 1st order xovers.
richj
richj
Also, 1st order fans tend to be purists & aren't keen on using op-amps. Come on... that statement is a load of absolute flannel...
Not to discourage Ist order users...too much has been mentioned that 1st order isn't for hi-fi....By far, floor standing cabinets with aligned drive units can hull out way more level than silly isobarik designs...the octet cabinet design is the only solution that solves lower midrange colouration from the LF units... a real sounder despite the amount of carpentry involved. Reason for oblique angles is to dispel the cabinet radiation nodes from upper order bass /lower midrange range from the LF driver units. Particle board cabinets are notorious for mid range resonants despite bracing.. Minimum wood thickness shown is 30mm, and one set of braces is shown st at 20cms apart. The midrange and upper units is in a sep cabinet.
Using reflex loading in base is great for uniform low end response and it will bang ones guts out.
The nub....I am willing to use op amps for active crossovers but everyone says that that my trumpet sound is better direct from tube amp with 1st order xover....so why complicate matters ? The other point is that tube amps don't burn up LS systems as SS amp do. I'm a fan where tube amps sound better with 1st order xovers.
richj
richj
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audiobomber said:
All true, but if you can fix the problem in the 1st place instead of bandaging it....
BTW, a BSC filter only attempts to fix the on-axis baffle step FR level problems -- and unless your box is designed to have a very smooth baffle-step roll-off will never be able to do that. I'd much rather just build a speaker that has no baffle step to compensate for.
I'm with rich. I like using tube amps and as little XO as possible. Still faster slopes would be nice sometimes -- still working on a higher order XO i can put in my system and not have it insert a veil. (too many projects -- not enuff time)
dave
planet10 said:
Other than speaker placement against a wall, how would you achieve that? Put a crossover at the step?
Amen to that! Speaking of which, I've always wondered... The PLLXO design I saw on the net had no provision for level control, and suggested a pot for matching. Wouldn't a pot change the hinge point?
I like tubes, but they're not the only answer.
audiobomber said:
http://www.t-linespeakers.org/tech/bafflestep/intro-bds.html
My preferred method is driver on the back, most often as a bipole, but the 0.5 method works too (and gives an opportunity to use another amp if going active)
You do have to concern yourself with changes in the input impedance of the amp (where i usually put the pot), but usually that R has limited effect unless quite low.
dave
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