I have built a pair of standmount speakers and got the components for the passive crossovers the other day. The crossover sounds great, but the notch filter I had planned is way too aggressive. However I found coincidently, that the treble control on my Yamaha amp which I was using to test them worked perfectly for taming the treble peak.
How do I build a shelf filter for the tweeter? It is a B&G Neo8 which has a flat impedance of 3.6Ohms.
When I set the amps treble control to -2dB it sounds great. I took a measurement of the amps output and have attached it below. How can I duplicate this in the crossover?
From the Rod Elliot site there is a baffle step compensation circuit but it is for line level. I guess I need a resistor and a cap in parallel with the tweeter but I’ve no idea how to determine the values.
Top measurement is no treble control adjustment and bottom is the treble control at -3dB, but I have decided its better at -2dB.
Thanks for your help peeps!
How do I build a shelf filter for the tweeter? It is a B&G Neo8 which has a flat impedance of 3.6Ohms.
When I set the amps treble control to -2dB it sounds great. I took a measurement of the amps output and have attached it below. How can I duplicate this in the crossover?
From the Rod Elliot site there is a baffle step compensation circuit but it is for line level. I guess I need a resistor and a cap in parallel with the tweeter but I’ve no idea how to determine the values.
Top measurement is no treble control adjustment and bottom is the treble control at -3dB, but I have decided its better at -2dB.
An externally hosted image should be here but it was not working when we last tested it.
Thanks for your help peeps!
It would do nearly the same but not quite. I think the slope being at (looks like) 3KHz helps fix a slight suck out around the crossover point as it brings the rest down closer to its level which is nice. I don't have the right value resistors to do an L-Pad right now so I might as well do the shelf if someone knows how to work it out for the impedance I have here?
What I want must be the same as passive baffle step compensation but at a higher frequency. Isn't thins a normal kind of circuit?
What I want must be the same as passive baffle step compensation but at a higher frequency. Isn't thins a normal kind of circuit?
Sure is - usually consisting of an inductor and parallel resistor. See http://www.quarter-wave.com/General/BSC_Calculator.xls for one way to caluclate the values, there are others.
Hi,
I found a formula for doing a passive baffle step correction but it is for doing -6dB and you set the -3dB point. How can I change this for getting only -2dB as the final attenuation of the shelf?
I see most of these suggest using an inductor. Is it not possible to use just a resistor and a cap in parallel across the signal line like rod Elliot does for his active baffle step circuit? I don't like inductors
Thanks guys!
I found a formula for doing a passive baffle step correction but it is for doing -6dB and you set the -3dB point. How can I change this for getting only -2dB as the final attenuation of the shelf?
I see most of these suggest using an inductor. Is it not possible to use just a resistor and a cap in parallel across the signal line like rod Elliot does for his active baffle step circuit? I don't like inductors
Thanks guys!
You could, using a standard Lpad layout except instead of the resistor across the tweeter terminals use a resistor and capacitor in series.
I don't know of an easy to use calculator for it, though. Probably the easiest thing to do would be model it in Speaker Workshop or other XO program and play with the values until you get what you want.
I don't know of an easy to use calculator for it, though. Probably the easiest thing to do would be model it in Speaker Workshop or other XO program and play with the values until you get what you want.
Thanks. Why do you suggest the one with an inductor? I have always felt inductors do far worse things to the sound than a cap in parallel.
Maybe this is a silly question but I'm silly... will the load presented to the rest of the crossover still be 3.6Ohms with this just before the tweeter?
By the way, The Edge is a great program. I have not needed to use it much but I know my friend does and it has been a lot of help here!
Maybe this is a silly question but I'm silly... will the load presented to the rest of the crossover still be 3.6Ohms with this just before the tweeter?
By the way, The Edge is a great program. I have not needed to use it much but I know my friend does and it has been a lot of help here!
Tenson said:
Well, the lower circuit is active, ie it needs to be inserted before the power amplifier. A passive circuit with a parallel capacitor would require a series resistor, and this would steal at least half of the power. No such circuit is suggested by The Edge.
The loading issue is not resolved in The Edge. It simply assumes that the load is R1, which is an approximation. Also, if the compensation is inserted after the crossover, the impedance seen by the crossover will be larger for lower frequencies.
Really, if BSC is to be performed thoroughly, the simple calculator in The Edge is too simple. It should be integrated with the crossover and loudspeaker design, and simulated as a whole.
Maybe a very dumb answer, but what's the problem if things sound great with adjusting the tone control of the amp to -2dB ? Why on earth are people afraid of using tone control or eqaulizers while passive correction circuits at speaker level most of the the times are doing much worse ? They introduce the same phase distortion as tone controls do but are more prone to distortion than line level correction filter (wich a tone control is actualy)
Thats not a silly answer, I would agree... however, I'm making them for a friend who won't be running them on the same amp. I think he does have tone controls but I can't be sure they will be the same. I'd rather stick in a filter and know they will work well on any amp.
I have ordered bits to do an L-Pad and a shelf filter. I will try both because if the L-Pad works just as well, it is probably better to avoid an inductor.
I have ordered bits to do an L-Pad and a shelf filter. I will try both because if the L-Pad works just as well, it is probably better to avoid an inductor.
Color me confused, what is your specific objection to an inductor as you have cited this as a reason repeatedly for taking a certain approach as opposed to several good suggestions offered?
Unless you are just adding a tweeter to a full range driver it seems like at least one inductor to roll off the woofer would be pretty indispensable..
In an application like this an air core inductor could be employed, eliminating core saturation, hysteresis and other non-linearities. Properly designed the network would be nearly lossless in-band and exhibit as good, perhaps significantly better linearity than one relying on a less than absolutely stellar cap, and it would be pretty simple, possibly as simple as a parallel RL network in series with the tweeter.. Best to design this into the overall x-over implementation to avoid surprises.
You might want to take another look at some of the other aspects of your tweeter x-over design before you proceed, something you said about the behavior in the x-over region is raising a flag in my brain.. LOL
Edit, fix typo, add comment
Unless you are just adding a tweeter to a full range driver it seems like at least one inductor to roll off the woofer would be pretty indispensable..
In an application like this an air core inductor could be employed, eliminating core saturation, hysteresis and other non-linearities. Properly designed the network would be nearly lossless in-band and exhibit as good, perhaps significantly better linearity than one relying on a less than absolutely stellar cap, and it would be pretty simple, possibly as simple as a parallel RL network in series with the tweeter.. Best to design this into the overall x-over implementation to avoid surprises.
You might want to take another look at some of the other aspects of your tweeter x-over design before you proceed, something you said about the behavior in the x-over region is raising a flag in my brain.. LOL
Edit, fix typo, add comment
With regards to inductors not being very nice components have a quick read of this - http://sound.westhost.com/lr-passive.htm#4.3
I have a notch filter which was intended to fix the treble peak but it is too strong. Even so, it has a 0.08mH inductor and when placed in the path with the tweeter I can hear compression. And not nice compression, its like a compressor set so it pumps slightly. I have a hunch this might be because of the thinner gauge wire (0.71mm). The one for the woofer is 1mm wire. Compression is also not so obvious in the bass region. As you say, it is pretty indispensable anyway.
There is a slight dip at the crossover point, probably from the tolerance of the components used. Its only about 1.5dB but if the shelf is used rather than an L-pad it fixes that. I'm not sure how audible that will be though so I will try the L-Pad as well, as it is a more simple solution.
I have to say the situation has improved now the crossover has had some run in time and I have placed the speakers in my normal listening room. I also do not toe the speakers in at all, so I listen more off-axis which helps I have found. Still I think the tweeter could use the L-pad at least.
I'm probably a bit fussy with the crossover as I have been running active for a few years now. Going back to passive isn't that nice
I have a notch filter which was intended to fix the treble peak but it is too strong. Even so, it has a 0.08mH inductor and when placed in the path with the tweeter I can hear compression. And not nice compression, its like a compressor set so it pumps slightly. I have a hunch this might be because of the thinner gauge wire (0.71mm). The one for the woofer is 1mm wire. Compression is also not so obvious in the bass region. As you say, it is pretty indispensable anyway.
There is a slight dip at the crossover point, probably from the tolerance of the components used. Its only about 1.5dB but if the shelf is used rather than an L-pad it fixes that. I'm not sure how audible that will be though so I will try the L-Pad as well, as it is a more simple solution.
I have to say the situation has improved now the crossover has had some run in time and I have placed the speakers in my normal listening room. I also do not toe the speakers in at all, so I listen more off-axis which helps I have found. Still I think the tweeter could use the L-pad at least.
I'm probably a bit fussy with the crossover as I have been running active for a few years now. Going back to passive isn't that nice
Rod has a lot of good information on his site, but the bit on inductors seems a bit over the top. The effects he frets over will be very, very small at normal home listening levels.
Your application would be an inductor in a tweeter circuit - quite low signal levels. I think you'd have a hard time hearing any negatives of an inductor. If you are really worried about it use a 14 gauge inductor.
I suspect that your "too aggressive notch filter" may have some effect other than inductive "compression" - and may not be operating as you think. Your break in experience may also be accommodation - you're getting used to the way they sound.
I also prefer active crossovers, but in this case I think a simple baffle step type circuit and Lpad will suffice.
Your application would be an inductor in a tweeter circuit - quite low signal levels. I think you'd have a hard time hearing any negatives of an inductor. If you are really worried about it use a 14 gauge inductor.
I suspect that your "too aggressive notch filter" may have some effect other than inductive "compression" - and may not be operating as you think. Your break in experience may also be accommodation - you're getting used to the way they sound.
I also prefer active crossovers, but in this case I think a simple baffle step type circuit and Lpad will suffice.
I don't think its just accommodation, I can still hear things I don't like about the passive, but the hard high frequencies have got a fair bit better. The main thing I notice about the passive is that when the volume is pumped up and the mix gets complicated, they seem to loose the thread some what. My previous actives just cut straight to the bone of a mix, even at stupid levels.
I haven't found it that bad going back to passive for a while though. I think if I were to use higher gauge inductors and better caps like good paper in oil's, the things I don’t like could be improved. Oh well, I know for next time!
I haven't found it that bad going back to passive for a while though. I think if I were to use higher gauge inductors and better caps like good paper in oil's, the things I don’t like could be improved. Oh well, I know for next time!
Hi Tenson,
I'm with Bob on this one, and Elliot's assertion that capacitors are so much better than inductors in regards to parasitic parameters just is not borne out in practice unless you spend huge amounts of money on them.
The typical non-polar electroytic has both significant amounts of ESL and ESR, and his assertion that ESL is largely due to lead inductance is rubbish.. That may be true of certain non-inductive construction in film caps, but most reasonably priced electrolytics have significant inductance due to their construction. (Not to mention other losses like DA/DF for which in any decent air core inductor there is usually no analog.)
When you come down to it you might as well say all electrodynamic drivers are rubbish as well due to the vc dcr, lumped capacitance not to mention the inherent inductance in the vc (without some of which the vc could not do its job
)
Also in terms of controlling Q of the x-over it is usually the case that pure reactances exhibit large spikes and resonances right at the inflection point - this is usually controlled by deliberately adding some series R to reduce Q to reasonable levels..
Your point about the active x-over vs passive is probably dead on, and I hope eventually to tri-amp my Onken based system and build line level active/passive x-overs to accomplish this.
I've no doubt allowing the amplifier to control the driver directly should have big sonic benefits..
I'm with Bob on this one, and Elliot's assertion that capacitors are so much better than inductors in regards to parasitic parameters just is not borne out in practice unless you spend huge amounts of money on them.
The typical non-polar electroytic has both significant amounts of ESL and ESR, and his assertion that ESL is largely due to lead inductance is rubbish..
That may be true of certain non-inductive construction in film caps, but most reasonably priced electrolytics have significant inductance due to their construction. (Not to mention other losses like DA/DF for which in any decent air core inductor there is usually no analog.)When you come down to it you might as well say all electrodynamic drivers are rubbish as well due to the vc dcr, lumped capacitance not to mention the inherent inductance in the vc (without some of which the vc could not do its job
) Also in terms of controlling Q of the x-over it is usually the case that pure reactances exhibit large spikes and resonances right at the inflection point - this is usually controlled by deliberately adding some series R to reduce Q to reasonable levels..
Your point about the active x-over vs passive is probably dead on, and I hope eventually to tri-amp my Onken based system and build line level active/passive x-overs to accomplish this.
I've no doubt allowing the amplifier to control the driver directly should have big sonic benefits..
Hi guys,
I tried a 1.5dB L-pad but it didn't help very much. The tweeter obviously went quieter and it helped a bit but the slightly top heavy balance was still there.
I tired a 2dB shelf filter with a 0.08mH inductor I already had and it works perfectly I think it does loose a tiny bit of detail compared to using the treble control on the amp nut at least now it can be used with good amps that don't have tone controls!
Thanks very much for your help.
If I had the chance I would use the Hi-Vi RT8-II tweeter as it doesn't have the bumpy frequency response and from my experience with the Neo8 it doesn't go anything like as low as it claims. 1.5KHz was as low as I could cross it.
Here are some pictures of them.
I tried a 1.5dB L-pad but it didn't help very much. The tweeter obviously went quieter and it helped a bit but the slightly top heavy balance was still there.
I tired a 2dB shelf filter with a 0.08mH inductor I already had and it works perfectly
I think it does loose a tiny bit of detail compared to using the treble control on the amp nut at least now it can be used with good amps that don't have tone controls!Thanks very much for your help.
If I had the chance I would use the Hi-Vi RT8-II tweeter as it doesn't have the bumpy frequency response and from my experience with the Neo8 it doesn't go anything like as low as it claims. 1.5KHz was as low as I could cross it.
Here are some pictures of them.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Now I know what crossover I'm using I have stuck the sides on and am waiting for them to dry. When that is done I will stick them on the end of my better amp and have a decent listen. I hope securing the side panels will bring a large improvement. I’ll let ya know.
My main complaint about them is that they get a bit messy compared to what I'm used to (PMC AML1 active monitors, about £4K of nice!) when things get loud and complex. However, considering what I'm comparing them too I think that’s fair enough.
My main complaint about them is that they get a bit messy compared to what I'm used to (PMC AML1 active monitors, about £4K of nice!) when things get loud and complex. However, considering what I'm comparing them too I think that’s fair enough.
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