Hi All,
I have a pair of JBL L1 standmount speakers and I'm looking to refresh their crossovers capacitors and change the resistors for better quality ones.
I compared the L1 crossovers to a JBL's L3 floorstanding speakers that use the same tweeters and also crossed at 3Khz (according to it's service manual) and found that for some reason the L3 crossover has "extra" resistor in paralel to the tweeter (15ohm) and different coil value (0.18mH in the L1 and 0.4mH in the L3).
As far as I understand and please correct me if I'm wrong it doesn't make any sense that 3uF+0.18mH cannot provide the same crossover point as 3uF+0.4mH, can someone please help me understand what is the crossover point for 3uF+0.18mH and 3uF+0.4mH ? JBL rate the 035TIA tweeter as 8 ohm and DCR of 3.5-4.2 ohm.
1. what are the actual calculated crossover points of the L1 and L3?
2. What is the purpose and effect of the "extra" 15 ohm resistor in parallel to the tweeter on the L3?
And.....I cannot find any branded 3uF capacitor to replace the original one, only 3.3uF, How using a 3.3uF capacitor instead of 3uF affects the crossover point considering it's 10% "extra" capacitance.
Thanks
I have a pair of JBL L1 standmount speakers and I'm looking to refresh their crossovers capacitors and change the resistors for better quality ones.
I compared the L1 crossovers to a JBL's L3 floorstanding speakers that use the same tweeters and also crossed at 3Khz (according to it's service manual) and found that for some reason the L3 crossover has "extra" resistor in paralel to the tweeter (15ohm) and different coil value (0.18mH in the L1 and 0.4mH in the L3).
As far as I understand and please correct me if I'm wrong it doesn't make any sense that 3uF+0.18mH cannot provide the same crossover point as 3uF+0.4mH, can someone please help me understand what is the crossover point for 3uF+0.18mH and 3uF+0.4mH ? JBL rate the 035TIA tweeter as 8 ohm and DCR of 3.5-4.2 ohm.
1. what are the actual calculated crossover points of the L1 and L3?
2. What is the purpose and effect of the "extra" 15 ohm resistor in parallel to the tweeter on the L3?
And.....I cannot find any branded 3uF capacitor to replace the original one, only 3.3uF, How using a 3.3uF capacitor instead of 3uF affects the crossover point considering it's 10% "extra" capacitance.
Thanks
R2 and R3 form a series/parallel L pad arrangement to attenuate the JBL L3 tweeter rather than just the single resistor R1 in the JBL L1.
To achieve 3.0 uF you can wire two 1.5 uF capacitors in parallel.
All I can say is that NL1 is a symmetrical, 2nd order crossover circuit which is consistent with a 3 kHz crossover point.
The obvious course of action is to stick to the NL1 layout which is designed to match the particular characteristics of the standmount.
Thanks Galu,
Just out of curiasity So if I want to attnuate the tweeter I on my L1 I can use the same value L-PAD resistor (15R) as in the L3 crossover? or is it better just to change the 7.5R ?
As for the 3uF capacitor, I know I can parallel 2 1.5uF capacitors to get 3uF value but I'm trying to avoid that because if I'll decide to use an "exotic" capacitor it will double the cost 🙂
Just out of curiasity So if I want to attnuate the tweeter I on my L1 I can use the same value L-PAD resistor (15R) as in the L3 crossover? or is it better just to change the 7.5R ?
As for the 3uF capacitor, I know I can parallel 2 1.5uF capacitors to get 3uF value but I'm trying to avoid that because if I'll decide to use an "exotic" capacitor it will double the cost 🙂
You could not incorporate the 15 ohm resistor without first moving R1 in NL1 to the same position as R2 in NL3.
However, the effect on the tweeter response would be uncertain, and I recommend sticking to the NL1 configuration, altering the value of R1 if necessary.
As for the 3.0 uF capacitor, I see that this value is available in the form of a quality Audyn 400 V polypropylene capacitor (see link).
https://willys-hifi.com/collections...lene-capacitors-400v-5?variant=36530269487263
Anything more "audiophile" would be unjustified in my book.
However, in the simple NL1 crossover, a variation in capacitor value of up to +/-10% would be permissible. So, if you wish, you can fill your boots with the most exotic 3.3 uF capacitor you can find!
However, the effect on the tweeter response would be uncertain, and I recommend sticking to the NL1 configuration, altering the value of R1 if necessary.
As for the 3.0 uF capacitor, I see that this value is available in the form of a quality Audyn 400 V polypropylene capacitor (see link).
https://willys-hifi.com/collections...lene-capacitors-400v-5?variant=36530269487263
Anything more "audiophile" would be unjustified in my book.
However, in the simple NL1 crossover, a variation in capacitor value of up to +/-10% would be permissible. So, if you wish, you can fill your boots with the most exotic 3.3 uF capacitor you can find!
Thanks again.
I've found that Clarity cap have 3uF capacitor in their CSA series.
BTW what is the purpose of the 0.01uF bypass capacitors?
I've found that Clarity cap have 3uF capacitor in their CSA series.
BTW what is the purpose of the 0.01uF bypass capacitors?
A large value capacitor exhibits inductance at a high enough frequency, an effect known as ESL (Equivalent Series Inductance).
The small value bypass capacitor eliminates the ESL.
Personally. I don't consider ESL to be an audible problem in loudspeaker crossovers, but some audiophiles with ears like bats would disagree!
The small value bypass capacitor eliminates the ESL.
Personally. I don't consider ESL to be an audible problem in loudspeaker crossovers, but some audiophiles with ears like bats would disagree!
My opinion is that there is no need to include the bypass capacitor if you employ a high quality tweeter capacitor.
I'm curious to know if JBL actually physically included a bypass capacitor across the woofer capacitor in your crossover.
If you feel you must include a bypass across the tweeter capacitor, the likes of an Audyn 0.01 uF at £2.50 would be more than "fancy" enough.
I'm curious to know if JBL actually physically included a bypass capacitor across the woofer capacitor in your crossover.
If you feel you must include a bypass across the tweeter capacitor, the likes of an Audyn 0.01 uF at £2.50 would be more than "fancy" enough.
The resistor across the tweeter will also reduce the impedance peak around the tweeter resonance, reducing that lower frequency region. On the other hand, placing the series resistor after the inductor will increase the lower tweeter frequencies by affecting the filter resonance. Finally, the combination of the larger inductor and the parallel resistor will reduce these frequencies.
While your concern about crossover frequencies points toward the potentially lower rolloff, it's not as important as the levels through the passband.
It would benefit you to simulate the pair as it's easy to talk about it but difficult to be specific without tests. Otherwise you could simply try both of them exactly as each of them are shown.
While your concern about crossover frequencies points toward the potentially lower rolloff, it's not as important as the levels through the passband.
It would benefit you to simulate the pair as it's easy to talk about it but difficult to be specific without tests. Otherwise you could simply try both of them exactly as each of them are shown.