How to choose rossover coils?

[scombridae]

Hello everyone! My name is Ari and I have finally taken steps to build 4344 inspired speakers. I've been roaming the forums and thinking of this project for over 15 years! I don't have room for 4345s and these will probably take up the entire living room. Since 2122H are difficult to source I am using 2123Hs and the 4344MKII charge coupled crossover below.

As I am acquiring parts, I ordered coils from Jantzen via HiFi collective in the UK. My question is how does DCR of a coil affect the crossover? According to the list below L2 is a .6mH with a DCR< 0.5 ohms. When I ordered this exact part the coil wires are 24 AWG gauge which seems very small. Is it better to use a coil with larger wires which will lessen the DCR? How will this change the crossover if at all? How do you guys best match coil specs?

Also how much would I benefit from air coils vs iron cored coils in different parts of the crossover?

Thanks for your help!

[RMC]

Hi Ari,

I have some info for you but i don't have time right now, i'll be back later tonight with the info.

Richard

[scombridae]

Hi Ari,

I have some info for you but i don't have time right now, i'll be back later tonight with the info.

Richard

That would be super and much appreciated!

[RMC]

Most of your questions are related to your 43 series project and as i mentioned earlier the 43 series isn't really my thing. So i'll let others deal with the 43 specifics.

As for the impossible aspect of adjusting a two-way electronic crossover without measuring setup and software i think its an exagerated statement. Its been done for decades in absence of the newer measurement/software gadgets. Btw the Ashly came with a user manual giving some hints. They might also have an application note for this, i haven't checked.

On the other hand you have two of the most practical assessment tools: your own two ears, unless you don't trust them.

Trial/error and personnal preferences are part of the process. inevitable. What is worth a sophisticated setup if you don't think its worth the money spent and/or don't really like how it sounds or is different than expected? Don't forget you build boxes to please yourself first and foremost, not the neighbor or the crowd...

[RMC]

Ari,

I don't have precise answers to all of your questions but the following should help.

Here's some guidelines for crossover coils. Most is from David B. Weems, Designing, building and testing your own speaker system, 4th edition.

Air-core coils are the preferred ones, however if of large value they can get sizeable and add a fair amout of resistance in the circuit. Ferrite-bobbin core coils provide lower resistance for identical inductance value.

In a woofer circuit, coil wire ought to be smaller gauge (larger size) to get lower resistance. But in a tweeter circuit coil wire may be smaller size (higher gauge). So there's also an energy aspect related to power level sent to each driver in a system. As you probably already know there is usually more sent to the LF than to HF devices. Coil wire size may depend on specific application, i.e. need "heavy duty" or not?

Weems' hi-fi speaker building book and projects don't normally target high power pro gear folks, nonetheless his coil wire recommendations are larger than the 24 ga you got on the coils purchased:

For inductances from .1 to .32 mH, use 24 ga wire. For .33 to .51 mH, use 22 ga wire. For .60 to 1.28 mH, use 20 ga wire. For 1.4 to 4.3 mH, use 18 ga wire.

That means for your L2 .6 mH coil, Weems recommends two sizes larger wire. Plus he has a note about this: "Avoid using wire of smaller diameter than that listed for a choke if possible." (p. 175).

I note on your parts list JBL uses Air Core for small values, but switch to Iron Core for 1.0 mH and more. Might be because of the size and/or resistance aspects mentioned above.

While writing this i'm having a quick look at a parts supplier catalog for inductors. Their standard Air Core inductor coils .1 to 2.0 mH use 20 ga wire and are rated 180 Watts; then from 3.0 to 10 mH they use Ferrite Core, rated 250 Watts and have 18 ga wire. Their high power inductors use 15 ga wire, high grade transformer steel laminate cores, these are rated 600 Watts, but are available 5 to 15 mH, unless special order.

I hope the above can be of some help to you.

Richard

[Ian Mackenzie]

Hi Ari,

I have built a number of these particular crossover for various JBL users.

The DCR of the inductor coils can have influence on the Q magnitude or Peak of the resonance of the filter. In the case of the midrange band pass filter this is important and in the UHF filter. This can have a marked effect on the voltage drive in the crossover region.

In all the 4344mk11 crossovers l assembled l have used air core inductors as the ferrite or iron core inductors do not document the current rating accurately before saturation. For a modest cost increase an air core inductor is a more ideal inductor without the effects of hysteresis as the dynamic signal increases.

If you cannot obtain a close Dcr value then add a small value power resistor in series with the inductor with a lower Dcr value to obtain the correct total Dcr.

I recommend you mount the parts on a non ferris material such plywood or acrylic sheet and hot melt glue with zip ties to attach the parts. Keep all inductors well clear of each other by two inches. An example of such construction is shown below l prepared earlier this year.

I used WAGO terminal connectors, adhesive zip tie pads and 7.5 amp pvc insulated flying leads soldered and wire wrapped from the components. All the terminations are also hot melt glued to prevent vibration and fatigue which may impact on reliability. These WAGO terminals have excellent electrical characteristics. This allows flexibility in changing out parts should trim adjustments be required. I prefer stranded flying leads to prevent fatigue of solid wire solder joints in loudspeaker crossover assembly. Each filter had its own star ground connection taken from a 15 amp rated ground spur from the input connection to the amplifier output ground terminal. This approach minimises the influence of ground potential variations from associated filters and IMD distortion.

There are other approaches to construction and this is just one example.

Unfortunately a good crossover implementation is never a cheap exercise.
Good luck with your project.

[scombridae]

Hi Ari,

I have built a number of these particular crossover for various JBL users.

The DCR of the inductor coils can have influence on the Q magnitude or Peak of the resonance of the filter. In the case of the midrange band pass filter this is important and in the UHF filter. This can have a marked effect on the voltage drive in the crossover region.

In all the 4344mk11 crossovers l assembled l have used air core inductors as the ferrite or iron core inductors do not document the current rating accurately before saturation. For a modest cost increase an air core inductor is a more ideal inductor without the effects of hysteresis as the dynamic signal increases.

If you cannot obtain a close Dcr value then add a small value power resistor in series with the inductor with a lower Dcr value to obtain the correct total Dcr.

I recommend you mount the parts on a non ferris material such plywood or acrylic sheet and hot melt glue with zip ties to attach the parts. Keep all inductors well clear of each other by two inches. An example of such construction is shown below l prepared earlier this year.

I used WAGO terminal connectors, adhesive zip tie pads and 7.5 amp pvc insulated flying leads soldered and wire wrapped from the components. All the terminations are also hot melt glued to prevent vibration and fatigue which may impact on reliability. These WAGO terminals have excellent electrical characteristics. This allows flexibility in changing out parts should trim adjustments be required. I prefer stranded flying leads to prevent fatigue of solid wire solder joints in loudspeaker crossover assembly. Each filter had its own star ground connection taken from a 15 amp rated ground spur from the input connection to the amplifier output ground terminal. This approach minimises the influence of ground potential variations from associated filters and IMD distortion.

There are other approaches to construction and this is just one example.

Unfortunately a good crossover implementation is never a cheap exercise.
Good luck with your project.

Hi Ian,

I've been following yours and Richard's posts for over a decade! I feel like you guys are pioneers on the 43xx subject.

These crossovers are absolutely beautiful and quite refined when compared to the past. I mean that in a practical sense, that they have been worked out and thoughtfully improved through your "natural selection" an evolution of parts.

Somehow I feel charge coupling is no longer the way to go, but I am committed now since I have all the solen caps.

Where do you source your coils from?

[Robh3606]

If you don't have access to a good simulation program like LEAP just stay close to the DCR values that JBL published for the crossover. You could go to all air wound coils but the cost and size can be prohibitive for the same DCR values.

I tend to go with minimum values for the woofer inductors to minimize sensitivity loss and for the shunts I will sometimes use a higher gage and use the inductors DCR instead of adding a low value resistor. Smaller part count same network response.

Rob

[Ian Mackenzie]

Hi Ian,

I've been following yours and Richard's posts for over a decade! I feel like you guys are pioneers on the 43xx subject.

These crossovers are absolutely beautiful and quite refined when compared to the past. I mean that in a practical sense, that they have been worked out and thoughtfully improved through your "natural selection" an evolution of parts.

Somehow I feel charge coupling is no longer the way to go, but I am committed now since I have all the solen caps.

Where do you source your coils from?

These coils are made by Jantzen and l source them from a local supplier.

Edit.

One thing to mention is that aspiring 43xx builders don’t always the the originally specified drivers. For example they might have a 2121 mid or a LE85 compression driver. No problem. I can measure these drivers and obtain the impedance and acoustic response and modify the network to accommodate these drivers until the user can obtain the other originally specified drivers.

[scombridae]

These coils are made by Jantzen and l source them from a local supplier.

Edit.

One thing to mention is that aspiring 43xx builders donÂ’t always the the originally specified drivers. For example they might have a 2121 mid or a LE85 compression driver. No problem. I can measure these drivers and obtain the impedance and acoustic response and modify the network to accommodate these drivers until the user can obtain the other originally specified drivers.

Thanks Ian! I am lucky enough to get very close to the 4344 MkII drivers. I have original 2235H, 2123h, 2426H Aquaplas coated by Upland Loudspeaker and the 2405 slot tweeter. I will be bi-amping with an Ashley XR1001. The thing I'm most confused about is the crossover slope for the woofer but I figured I would play around with the "response" knob until it sounded best.,,, the monkey test Thanks to your earlier posts, you have given me the confidence to live a dream!

[RMC]

The usual rhetoric when one doesn't swallow all that is said or his things catch up with him.

Seems something was forgotten, "the 43 series isn't really my thing, i intervene in 43xx related threads occasionaly, not much more."

When newcomer OP posted i waited to see if others would take care of him, nobody showed up. I did and was here before Mackenzie, while he stood on the sidelines. The OP thanked me for helping him and others:"This information is very helpful! Thank you for taking the time and effort to help me and anyone else that has these questions."

Had signalled i would not stick around long, but when i saw the Ashly not being so good anymore i decided to stay a little longer considering the previous comments in post 13:

"Your Ashley crossover will give a competent crossover region with some trial and and error adjustments."

"I recommend you tweak the Ashley crossover for best subjective performance for now," by ear obviously. Both statements not disputed.

The wind changed direction in post 19, with an alleged procedure he raised re the Rane Manual, also shooting an arrow in my direction that "It’s not done by ear. It’s a case of doing it correctly or not at all..." Turns out Rane appeared to have a different view (pic posted), himself too in the above statement.

Instead of explaining his disagreement with manufacturer position he prefers to attack me. When one prefers the latter its a sign the case might be weak.

Having both Ashly and Rane xo i'm certainly interested in what is said about these, inquiring is relevant plus these are not even 43 series gear. That members are provided with different and relevant manufacturer or expert info is an asset in making one's own decisions.

Men who screw up assume, correct and move on, while here its "assume" and leave the thread! Looks like trying to take control of the narrative and of any info given as if he owned this thread, though he waited for someone else to "break the ice" first, now claims to be "those directly involved!

When a player plays fair game there's less reason to jump in or stick around. At this time there's no justification to leave, or to stay for that matter.

Will continue to look at threads, including this one and others, and post as i see fit or the situation requires.

[scombridae]

The usual rhetoric when one doesn't swallow all that is said or his things catch up with him.

Seems something was forgotten, "the 43 series isn't really my thing, i intervene in 43xx related threads occasionaly, not much more."

When newcomer OP posted i waited to see if others would take care of him, nobody showed up. I did and was here before Mackenzie, while he stood on the sidelines. The OP thanked me for helping him and others:"This information is very helpful! Thank you for taking the time and effort to help me and anyone else that has these questions."

Had signalled i would not stick around long, but when i saw the Ashly not being so good anymore i decided to stay a little longer considering the previous comments in post 13:

"Your Ashley crossover will give a competent crossover region with some trial and and error adjustments."

"I recommend you tweak the Ashley crossover for best subjective performance for now," by ear obviously. Both statements not disputed.

The wind changed direction in post 19, with an alleged procedure he raised re the Rane Manual, also shooting an arrow in my direction that "ItÂ’s not done by ear. ItÂ’s a case of doing it correctly or not at all..." Turns out Rane appeared to have a different view (pic posted), himself too in the above statement.

Instead of explaining his disagreement with manufacturer position he prefers to attack me. When one prefers the latter its a sign the case might be weak.

Having both Ashly and Rane xo i'm certainly interested in what is said about these, inquiring is relevant plus these are not even 43 series gear. That members are provided with different and relevant manufacturer or expert info is an asset in making one's own decisions.

Men who screw up assume, correct and move on, while here its "assume" and leave the thread! Looks like trying to take control of the narrative and of any info given as if he owned this thread, though he waited for someone else to "break the ice" first, now claims to be "those directly involved!

When a player plays fair game there's less reason to jump in or stick around. At this time there's no justification to leave, or to stay for that matter.

Will continue to look at threads, including this one and others, and post as i see fit or the situation requires.

Richard and Ian,

Thank you both for your input and sticking your necks out in this jungle forum. Your contributions have helped me tremendously here. This is all excellent stuff!

I'm sure with the correct measurement tools and such, balancing a 4 way speaker in a room with less than ideal acoustics would help a lot. That said, there's something to be said about being able to tune a guitar by ear. I once took a guitar class in junior college and at the first meeting the teacher went around and tuned everyone's guitar in about 15minutes. I think there were 30 people in class, so we are talking 30 seconds to tune the guitar. It was the kind of teacher/student introduction that immediately established great respect for the teacher. It's enjoyable to tune and play a musical instrument. The funny thing is, as soon as one gets close to tuning in key, the sound changes and a retune is needed. What was once "flat or neutral" is slightly different. Making music is like that. And part of the enjoyment in making it is the organic nature of all this process. As much as we all love making and tuning speakers, in the end we all LOVE music.

You are both teachers with different styles. I am a student like many on this forum who are learning. We are all blessed to have this forum with access to experienced teachers as yourselves. 25 years ago I wouldn't have a clue on how to build these speakers and any access to help. We are all fortunate that this forum allows all of us to contribute and learn from each other, so please don't chase each other off. It's doesn't benefit the students. I really appreciate both Richard's and Ian's help on this and you both provide very valuable information!

Back to the subject, I'm guessing there are many a sage speaker enthusiast who can get very close to tuning a 4 way by ear. I am guessing I am not that person for I don't have any experience with the 43XX 4way series. But I am enjoying making the speakers, though it is a beast of a project. I'm assuming it will be very difficult to get all the drivers to sound or blend in a neutral way especially because I've never heard this species before and have no idea what it "should" sound like. Most likely I will play with all the knobs, put on familiar music, adjust, adjust, get closer and then decide months from now I will need to purchase mics and software and see how far off I really am.

I guess what I'm trying to say is whatever lines have been crossed in the past or mud slinged, it is most important to see that both a scientific method and more organic approach are equally valuable and needed. And I'm assuming like most humans you both engage in both methods of speaker tuning and you both use a more scientific approach to finalize the product.

I welcome both of you to continue to contribute on this thread and if you have any other "metaphysical" tips to tuning these monsters to tie me over until I get up the courage to do it more scientifically, it will help me and a large chunk of followers.

Thank YOU Both!

[RMC]

Since Rane crossover manual was mentioned, i happen to own for years two Rane crossovers, along with the Data Sheet (4 pages, including an application note) as well as the 19 page Manual, both provided in Rane's packaging at time of purchase.

There's nothing rocket science or sophisticated seen in this regard, in fact the explanations given are pretty simple and straightforward.

As for matching of the levels the manual details different procedures alluded to on pic.

A number of meanings were attributed to SOA, however in the audio field more often than not it was used to describe Safe Operating Area e.g. in relation to amp output stage.

[Ian Mackenzie]

Hi Richard

I must have had a seniors moment.

Too bad you actually went to the trouble of looking for nothing.

Besides you said the 43xx was not your thing? So why are you in this thread?

I look forward to you publishing a long thread on your own loudspeaker design with references to the way back machine.

Attached is a screen dump of an official JBL 4350 manual referring to the Biamp balance procedure.

As l mentioned earlier the mater of obtaining the correct tonal balance using the Lpads is much more involved in the 4343-4345. One would assert if you in fact owned one of these systems you would not be gum slapping over this. But of course you formally stated the 43XX are not your thing. Your just here to stir up trouble like you always have. So kindly leave this thread to those directly involved.

[scombridae]

Ari,

I don't have precise answers to all of your questions but the following should help.

Here's some guidelines for crossover coils. Most is from David B. Weems, Designing, building and testing your own speaker system, 4th edition.

Air-core coils are the preferred ones, however if of large value they can get sizeable and add a fair amout of resistance in the circuit. Ferrite-bobbin core coils provide lower resistance for identical inductance value.

In a woofer circuit, coil wire ought to be smaller gauge (larger size) to get lower resistance. But in a tweeter circuit coil wire may be smaller size (higher gauge). So there's also an energy aspect related to power level sent to each driver in a system. As you probably already know there is usually more sent to the LF than to HF devices. Coil wire size may depend on specific application, i.e. need "heavy duty" or not?

Weems' hi-fi speaker building book and projects don't normally target high power pro gear folks, nonetheless his coil wire recommendations are larger than the 24 ga you got on the coils purchased:

For inductances from .1 to .32 mH, use 24 ga wire. For .33 to .51 mH, use 22 ga wire. For .60 to 1.28 mH, use 20 ga wire. For 1.4 to 4.3 mH, use 18 ga wire.

That means for your L2 .6 mH coil, Weems recommends two sizes larger wire. Plus he has a note about this: "Avoid using wire of smaller diameter than that listed for a choke if possible." (p. 175).

I note on your parts list JBL uses Air Core for small values, but switch to Iron Core for 1.0 mH and more. Might be because of the size and/or resistance aspects mentioned above.

While writing this i'm having a quick look at a parts supplier catalog for inductors. Their standard Air Core inductor coils .1 to 2.0 mH use 20 ga wire and are rated 180 Watts; then from 3.0 to 10 mH they use Ferrite Core, rated 250 Watts and have 18 ga wire. Their high power inductors use 15 ga wire, high grade transformer steel laminate cores, these are rated 600 Watts, but are available 5 to 15 mH, unless special order.

I hope the above can be of some help to you.

Richard

Richard,

This information is very helpful! Thank you for taking the time and effort to help me and anyone else that has these questions.

I read somewhere that it isn't necessary to use air cored coils if it is a shunt or used in parallel with the driver. Is this correct?

I will review my list and size the coils accordingly.