Thanks. I've got this result.
C1 = 5.3E-5 farads (so I need a cap value of 5.3?)
L1 = 0.0033970276008493 henries
Excuse my ignorance but with the butterworth diagram that means no bi wiring?
5.3e-5=53e-6= 56uF.
You can bi-wire, not that it will make a difference anything like a well tuned crossover. The diagram just shows the high and low pass tapped on to the usual single feed.
For tuning pick off the driver impedance from the published or measured curves at the crossover frequency. Buy some slightly undersized caps for the main unit and a few smaller values to parallel on if needed. Same for the inductor, only series to increase value. You can rerun calculations at different turnover points to get a smarter idea about what values to buy..
You can bi-wire, not that it will make a difference anything like a well tuned crossover. The diagram just shows the high and low pass tapped on to the usual single feed.
For tuning pick off the driver impedance from the published or measured curves at the crossover frequency. Buy some slightly undersized caps for the main unit and a few smaller values to parallel on if needed. Same for the inductor, only series to increase value. You can rerun calculations at different turnover points to get a smarter idea about what values to buy..
Thanks for the sensible advice.
Yes, thats the figure I got on the Erse site, I thought I'd made a mistake. I'm assuming the ohm inputs are the overall driver rating and not the ohm level at point of crossover?
so that value is going to be expensive if i choose a decent cap..
Passive line level XO and active start to look really attractive when parts for speaker level XO cost more than the drivers
TLS.org | Passive Line-Level Crossover
chris, I'm looking at the link .. for me anything like this is..well, its a bit like the swedish chef making a pastilla
could you explain it in very simple terms?
btw I was thinking to either go for pulse x's (true film and foil 50uf caps are crazy prices)or try a big fat industrial oil type capacitor. both are inexpensive and it might be interesting to see which is preferable with the alpair. cd I bypass with a nice low value cap if needed?
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chris, I'm looking at the link .. for me anything like this is..well, its a bit like the swedish chef making a pastilla
could you explain it in very simple terms?
btw I was thinking to either go for pulse x's (true film and foil 50uf caps are crazy prices)or try a big fat industrial oil type capacitor. both are inexpensive and it might be interesting to see which is preferable with the alpair. cd I bypass with a nice low value cap if needed?
well if you're anything like me, even an explanation in simple enough terms that I fool myself that I understand it will soon evaporate from my memory
this type of filter uses the amplifiers' input impedance as one of the formula's operands, any changes in amps might require new parts values
however, there is a calculator included - you enter the amp's input impedance and desired XO frequency, and it does the rest
http://homepage.mac.com/planet10/TLS/downloads/PLLXO_Calculator.xls.zip
FWIW, the calculated parts are small enough that they can easily be installed at the amp's input jacks - I did exactly that about 10 years ago during some mods to a pair of Decware Zen C amps for a simple 2 way active system - one was filtered LP and the other HP
This particular model had 2 pairs of RCAs and a toggle switch for adjusting the bias of driver tube by adding cathode load resistors. It was easy to re-purpose these parts to allow for bypass of the input filters to run full range.
Worked like a charm, and without getting silly exotic, the cost of parts for the 2 amps was under $50.
respectfully - certainly valid to test for optimal C value, but I don't believe the difference wouldn't be audible between cheap ELs and decent film types when used at speaker level
Bill, its worth trying the PLLXO, for sure.
I'm using a 1st order PLLXO (which is silly simple to build) for a CHR70 in a sealed enclosure with Eminence 15As in an OB (ala MJK) and am very satisfied. I've also played with a 2nd order based on those same formulas. Even with reversed polarity on one of the outputs with the 2nd order, so far still I prefer the 1st order. You can cobble up a test with a solderless test board and a few really cheap components.
Of course, going this way is only feasible if you have two amps...
I've been using cheap components so far but have some "higher quality" ones on the way and have built a A/B test rig to see if the sound quality difference is actually significant.
I'm using a 1st order PLLXO (which is silly simple to build) for a CHR70 in a sealed enclosure with Eminence 15As in an OB (ala MJK) and am very satisfied. I've also played with a 2nd order based on those same formulas. Even with reversed polarity on one of the outputs with the 2nd order, so far still I prefer the 1st order. You can cobble up a test with a solderless test board and a few really cheap components.
Of course, going this way is only feasible if you have two amps...
I've been using cheap components so far but have some "higher quality" ones on the way and have built a A/B test rig to see if the sound quality difference is actually significant.
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