Hello,
I'm a complete noob to diy. I've been an audiophile for more than two decades. Recently I made a friend who had built a set of the CSS Criton 1tdx speakers. They sounded great. I decided to build a set, but use better parts in the crossover. I am matching the values, just using upgraded resistors such as duelund and copper foil inductors. Which leads me to my dilemma. I can't source the required 3.0mH inductor (outside of a jantzen wire one). I can find a 3.3 mH and a 2.7mH mundorf. I can't seem to find any explanation of the effects of using a slightly higher or slightly lower value inductor. Can anyone explain it in simple terms for me? Can I substitute a sightly different value without destroying the sound? Thanks everyone.
I'm a complete noob to diy. I've been an audiophile for more than two decades. Recently I made a friend who had built a set of the CSS Criton 1tdx speakers. They sounded great. I decided to build a set, but use better parts in the crossover. I am matching the values, just using upgraded resistors such as duelund and copper foil inductors. Which leads me to my dilemma. I can't source the required 3.0mH inductor (outside of a jantzen wire one). I can find a 3.3 mH and a 2.7mH mundorf. I can't seem to find any explanation of the effects of using a slightly higher or slightly lower value inductor. Can anyone explain it in simple terms for me? Can I substitute a sightly different value without destroying the sound? Thanks everyone.
The mundorf is a foil inductor so I'm not sure how to even begin without destroying the inductor. If I don't unwind some of the coil, is there a rule of thumb for what effects are caused by a value change like I am faced with of .3mH higher or lower? That's again for the reply to what I'll sure is a very simple question for you guys.
The different inductor value will slightly change the frequency response of the circuit that it is in. That change might be subtle that you's never notice, or skew things in a good or bad way.
What's the crossover schematic? Can you post it, or at least give us an idea of where the inductor is used.
What's the crossover schematic? Can you post it, or at least give us an idea of where the inductor is used.
To give you a visual, here is a 2.7mH vs 3mH inductor as typically used in a two-way high pass filter, and a low pass filter. The gray line is the 3mH inductor, the 2.7 is the blue line.
You might see 1dB difference at the crossover point. That's just the most basic idea of what happens. An inductor impedes the passage of high frequencies. The larger the value of the inductor, the lower the frequencies that it impedes. So in a high pass filter a 2.7mH inductor with allow slightly more highs thru than a 3mH inductor when connected to the same speaker driver.
You might see 1dB difference at the crossover point. That's just the most basic idea of what happens. An inductor impedes the passage of high frequencies. The larger the value of the inductor, the lower the frequencies that it impedes. So in a high pass filter a 2.7mH inductor with allow slightly more highs thru than a 3mH inductor when connected to the same speaker driver.
Attachments
And perhaps don't be a slave to your intentions. How much "better" will that one part be by being foil rather than wire? Or the other way, how much "worse" will it be if it is not foil? Plenty of excellent sounding speakers have been made using wire inductors instead of foil.
Three or four of the most amazing, life-like systems I've heard in my life were built with wire wound inductors. Didn't hold them back a bit. 😉
You guys are awesome. Thanks for the education. I'm going to try and attach a pic of the crossover and parts list that's been made for my friends set of speakers. They are a simple two way bookshelf. Fwiw they are ported which isn't my favorite. Honestly the mid bass was every so sightly strong. If a different value inductor will lower the mid bass then it might be advantageous. I was actually going to experiment with plugging the port to see how it changes the sound once the speakers are finished.
.3mH 16gauge inductor
3.0 mH 16 gauge inductor
6r ohm 10w resistor
1r8 ohm 12w resistor
6r2 ohm 12w resistor
6.2micro F cap 400vdc
12 micro f cap 250vdc
.3mH 16gauge inductor
3.0 mH 16 gauge inductor
6r ohm 10w resistor
1r8 ohm 12w resistor
6r2 ohm 12w resistor
6.2micro F cap 400vdc
12 micro f cap 250vdc
Attachments
Thanks for the photo. I can't quite make out all the values, but the woofer inductor is a 15 gauge 3mH inductor. It look like the tweeter inductor is a 0.3mH foil? The tweeter cap appears to be 5.6uF. Your list helps. 
Those values seem unusual for a normal two-way woofer/tweeter crossover, but it might have to do with driver impedance and attenuation.
Those values seem unusual for a normal two-way woofer/tweeter crossover, but it might have to do with driver impedance and attenuation.I've sent my buddy a link to this thread. He actually knows and understands this stuff. Hopefully he'll chime in. I'm just trying to use the best parts that are within reason cost wise. The goal is to have two sets of like speakers with some small differences to see if we can hear any difference. I've never done anything like this so I'm really in the dark. The initial set of speakers he built were surprisingly good and not even broken in!
if the speakers are well designed and the crossover is optimised, 3.0 to 3.3mH is unacceptable, as it will change transfer function (+/- 0.5-1dB in sensitive areas (1-2khz) and phase tracking between mid to tweeter (changing the soundstage performance)
if you want to improve, use bigger wire/coil to 14 or 12 AWG but u need to check the DCR differences if the woofer needs resistance for box's Q (sometimes higher DCR needed to get higher Q to give more body to the bass).
if you want to improve, use bigger wire/coil to 14 or 12 AWG but u need to check the DCR differences if the woofer needs resistance for box's Q (sometimes higher DCR needed to get higher Q to give more body to the bass).
And if it is your intent to compare same speakers with different crossover parts. Make sure to accurately MEASURE each part. You might find the foil coil sounds different from the wire ones, but it might be because the foil ones have a different induction. Or maybe a cap that should be 2uf is 2.15uf in one form and 1.95uf in the other.so it is the cap value rather than the material you are hearing.
So I got word back from Chris at parts connexion. He'll unwind the 3.3 foil inductor for me to the desired 3.0. yay problem solved...I think 🥴. Thanks again for y'all's help. I learned a ton already. Hopefully I can get parts ordered and get started!