Does a smaller or bigger guage of inductor sound better for high pass sections of passive crossovers? Should I spend the extra money on the larger inductors or will this not make a difference?
Thanks guys,
sardonx
Thanks guys,
sardonx
Fair question. The theory behind using the larger gauge wire for inductors in Xovers is to reduce the DC resistance of the inductor or coil. In low-pass sections this has two advantages; the lower resistance allows more power to reach the speaker and not be dissipated in heating the inductor and also the lower resistance will help maintain a lower DC resistance of the whole wiring system from the amp' to the voice coil. This will aid the damping of the bass speaker. Now, neither issue will really apply to the same extent with a hi-pass section so if you have a limited budget it makes sense to invest more in a low DC resistance inductor for the bass speaker. On the other hand some of the coils in low pass section can get pretty big and if you attempt really low DC resistance you ger a very big coil you are asking the signal to travel through a very long piece of wire and most of us are trying to move our signal through short wires.
Like most things a good listening test will help but by then you've wound at least ONE large inductor.
Just re-read your post. It's really about the Hi-pass isn't it? If you read the literature you can get some people specifiying very precise values for the R of hi-pass coils. At one stage KEF wanted a small inductor (0.3 mh) to have 0.55 ohms DC resistance when feeding its T27 through a complicted computer designed network. That would be after using more sophisticated facilities than most of us have. On another track VIFA went through a phase when they used larger coils and smaller caps so as to have a low impedance path across the voice coil of their tweeters and aid damping of the resonance. (The LC time constant was the same for the relevant xover point but they just scaled the inductors up and the caps down to some extent.) This only applies when the coil is the last component before the driver. IE 2nd and 4th order networks.
Like a lot of things on this forum you will probably end up being told to experiment and see what you enjoy. It would be interesting to hear the result of what you come up with. I can't recall seeing much published on this question.
So these comments probably haven't helped at all! Sorry.
Jonathan
Like most things a good listening test will help but by then you've wound at least ONE large inductor.
Just re-read your post. It's really about the Hi-pass isn't it? If you read the literature you can get some people specifiying very precise values for the R of hi-pass coils. At one stage KEF wanted a small inductor (0.3 mh) to have 0.55 ohms DC resistance when feeding its T27 through a complicted computer designed network. That would be after using more sophisticated facilities than most of us have. On another track VIFA went through a phase when they used larger coils and smaller caps so as to have a low impedance path across the voice coil of their tweeters and aid damping of the resonance. (The LC time constant was the same for the relevant xover point but they just scaled the inductors up and the caps down to some extent.) This only applies when the coil is the last component before the driver. IE 2nd and 4th order networks.
Like a lot of things on this forum you will probably end up being told to experiment and see what you enjoy. It would be interesting to hear the result of what you come up with. I can't recall seeing much published on this question.
So these comments probably haven't helped at all! Sorry.
Jonathan
Hey.. thanks anyways! I think i will go for the large coils all around.... I'm trying to go all out for my next project!
Sardonx
Sardonx
I don't bother with large coils and/or solid cores for HP sections. They are necessary with LP sections to keep DCR, and thus insertion losses, low. Those also have to deal with large amounts of current, so a large gauge is required. But in a HP section all the coils are doing is shunting current to ground after it has already passed through at least one capacitor, which means there isn't a lot of current there and small gauge air core coils will do.
sardonx said:
Yes there will be a difference, but it will be small. In the high-pass section, the coils are typically connected to ground. Take the second order filter as an example, with a capacitor in series and an inductor in parallel. The impedance of the inductor decreses toward lower frequencies, and the impedance of the capacitor increases. The net effect of this is a 12 dB/oct slope below cutoff. Now, if the inductor has a series resistance, its impedance will stop to decrease at a certain frequency and the slope will ultimately be only 6 dB/oct.
Also, the resistance can affect the behaviour around the cutoff frequency, and it is hard to tell how much without a simulation.
However, this happens to any coil, the question is only at which frequency. Usually it is not a big problem in the HP section, but any filter design should be simulated with the resistances included, and then it is easy to see the effects of the coil resistance.
So, the bottom line here is; yes it can matter, probably less in the HP section than in the LP section, and a simulation is always good to do.
I know that this is an old thread, but I will put my 2cents in anyway.
I am curious as to how much difference wire size makes in practice (within reasonable limits) and surely it makes a big difference as to what power the speakers are handling. Electrical resistance is proportional to voltage and current (using the simple equation and, for now, ignoring alternating current effects).
My point being that if you are building large and powerful speaker and driving them hard, then you will experience losses, but if you are building some bookshelves and powering them from an ebay T amp (as I am now) then it may not be worth the extra dollars.
Obviously Svante makes a good point about the effect of series resistance on the crossover frequency etc. But i wonder how many people actually measure the R, L and C values (not to mention the drivers REAL values) anyway, all of these have a %error from the face value - sometimes a large one. Lets not even get into the effect that nature of the room that the speaker goes in can have on sound...
I am interested if anyone knows of any actual tests on this matter - i.e. built an accurate crossover and then changed an inductor out for a smaller wire (higher resistance) model. Even better, built 1x 'perfect' XO and 1x cheaper and compared the 2.
Maybe i am off the mark...
I am curious as to how much difference wire size makes in practice (within reasonable limits) and surely it makes a big difference as to what power the speakers are handling. Electrical resistance is proportional to voltage and current (using the simple equation and, for now, ignoring alternating current effects).
My point being that if you are building large and powerful speaker and driving them hard, then you will experience losses, but if you are building some bookshelves and powering them from an ebay T amp (as I am now) then it may not be worth the extra dollars.
Obviously Svante makes a good point about the effect of series resistance on the crossover frequency etc. But i wonder how many people actually measure the R, L and C values (not to mention the drivers REAL values) anyway, all of these have a %error from the face value - sometimes a large one. Lets not even get into the effect that nature of the room that the speaker goes in can have on sound...
I am interested if anyone knows of any actual tests on this matter - i.e. built an accurate crossover and then changed an inductor out for a smaller wire (higher resistance) model. Even better, built 1x 'perfect' XO and 1x cheaper and compared the 2.
Maybe i am off the mark...
12# or 13# would be good. larger ones will be difficult to wind . the larger wire, the smaller resistance= better frequency pass and more exact crossing point
It does very the Q slightly, but should not measurably effect frequency. If you want to see how much, make a model in Spice and make the efforts Dansforth recommends.
I have, but I can't say the speakers were good enough that I could detect any deference. (compared 14 to 18 ga air core) I use the smaller gauges, like 16 or 18 on the tweeters, and spend my money on the LP coils or to add some eq where needed. Others may have their own experiences.
I have, but I can't say the speakers were good enough that I could detect any deference. (compared 14 to 18 ga air core) I use the smaller gauges, like 16 or 18 on the tweeters, and spend my money on the LP coils or to add some eq where needed. Others may have their own experiences.
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