Hi Sean and welcome to the forum!
The usual question to ask back is "What is wrong with the present crossover?".
There's already a plastic film capacitor which can't go wrong - you could put a high voltage polypropylene cap in there and struggle to hear a difference.
The bass inductor is iron or ferrite cored. A replacement air cored inductor would be physically much larger and its larger DC resistance might alter the sound balance for the worse.
Personally, I would leave well enough alone, but you may receive many contradictory suggestions from the community!
The usual question to ask back is "What is wrong with the present crossover?".
There's already a plastic film capacitor which can't go wrong - you could put a high voltage polypropylene cap in there and struggle to hear a difference.
The bass inductor is iron or ferrite cored. A replacement air cored inductor would be physically much larger and its larger DC resistance might alter the sound balance for the worse.
Personally, I would leave well enough alone, but you may receive many contradictory suggestions from the community!
Thanks for the response, @Galu! I appreciate it. Great question. There is nothing wrong with the crossover. 
I'm a bit of a tweaker and have always wondered about the quality of the crossover in these speakers. They are a 1st-order crossover. They were very well regarded in their heyday about 15 years ago and they were more of a mid-tier Dynaudio line and so I imagine that maybe parts quality was one of the areas they cut some corners to meet a price point. I'm still learning and so my experience level in identifying parts quality is pretty novice.
I had a hunch the inductor, if upgraded, would likely be too large, as you said. I wasn't sure if that plastic film cap would be something you guys would flag as cheap or not. How about those resistors, any way to tell their quality and if they are even worth changing?
I'm a bit of a tweaker and have always wondered about the quality of the crossover in these speakers. They are a 1st-order crossover. They were very well regarded in their heyday about 15 years ago and they were more of a mid-tier Dynaudio line and so I imagine that maybe parts quality was one of the areas they cut some corners to meet a price point. I'm still learning and so my experience level in identifying parts quality is pretty novice. I had a hunch the inductor, if upgraded, would likely be too large, as you said. I wasn't sure if that plastic film cap would be something you guys would flag as cheap or not. How about those resistors, any way to tell their quality and if they are even worth changing?
The first stage: Measure both inductivity and DC resistance of the ferrite core inductor. Replace it with an air core inductor with the same inductivity and DC resistance. Leave everything else as-is.
The second stage (if you are willing to spend some time and money, maybe unnecessary): Try different 4.7 microF capacitor (MKP, etc.). Replace ceramic wire-wound resistor with the same value metal-oxide resistors.
The second stage (if you are willing to spend some time and money, maybe unnecessary): Try different 4.7 microF capacitor (MKP, etc.). Replace ceramic wire-wound resistor with the same value metal-oxide resistors.
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Normally, crossover tweaking involves the design of the circuit, or even just changing values slightly if you have a reason to do that. Often improvements can be made, sometimes it is hard work, often measurements are the better way to ensure you are moving in the right direction.
Resistors, if I feel inclined to tweak for effects I think the best value can be where DC is present, in an amp. Small value crossover resistors don't do much for me.
Resistors, if I feel inclined to tweak for effects I think the best value can be where DC is present, in an amp. Small value crossover resistors don't do much for me.
Resistors and inductors and voicecoils are all made of copper wire. So it's questionable if much improvement is possible there.
In theory, the big bass coil with the ferrite former could be replaced with an aircoil. It ought to sound a bit more linear. Upgrading capacitors is a possibility, but better ones tend to be way bigger. TBH, no-one has ever found the smoking gun in measurement that says expensive capacitors actually do anything.
That would presuppose you measure the coil value with a good multimeter with an inductance scale,
Dynaudio have a fine reputation for midbass drivers with a carefully contoured mechanical response. Their tweeters are designed to work well with simple filters.
But the fact is, that small speakers don't go loud without distortion. This is because a small driver moves much further with loud bass, so gets non-linear. Heating effects always favour higher rated components, but really ought to be negligible in home HiFi. A speaker like this is fine for small rooms, in a big room you need bigger stuff. Even a three way.
I have to agree with Galu. Leave them as they are, especially for resale value.
In theory, the big bass coil with the ferrite former could be replaced with an aircoil. It ought to sound a bit more linear. Upgrading capacitors is a possibility, but better ones tend to be way bigger. TBH, no-one has ever found the smoking gun in measurement that says expensive capacitors actually do anything.
That would presuppose you measure the coil value with a good multimeter with an inductance scale,
Dynaudio have a fine reputation for midbass drivers with a carefully contoured mechanical response. Their tweeters are designed to work well with simple filters.
But the fact is, that small speakers don't go loud without distortion. This is because a small driver moves much further with loud bass, so gets non-linear. Heating effects always favour higher rated components, but really ought to be negligible in home HiFi. A speaker like this is fine for small rooms, in a big room you need bigger stuff. Even a three way.
I have to agree with Galu. Leave them as they are, especially for resale value.
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If the ferrite has a u of 1000 which is average I believe you need at least 30 times as many turns and the wire will need to be at least 5 times as thick for the same inductance, resistance. Is that right? Thats a large coil, 1000 times? as much copper. The different size will effect the inductance some how and the length of wire. Lots of variables so wondering if someone has some real data.
Dynaudio will certainly have worked to a budget - crossovers represent one area in which manufacturing costs can be saved.
However, the components will have been chosen to match the characteristics of the drivers and upgrading would require a complete crossover redesign - fun for some, but perhaps not for the uninitiated!
I didn't see anything wrong in what Dynaudio did there:
You could do something vaguely different in this admirable little 5" Troels Gravesen design: Peerless HDS PPB 830860
But really, what do you expect from a 7L box?
You ain't gonna shake the room like my 12" Celestion Ditton 44's:
Actually, I never run them. I don't want to get evicted from my bijou seaside apartment.
That ferrite core inductor look like about 1 mH, or so. The air core inductor with the same inductivity and DC resitance is bigger, but not as much as you describe.
I have done the right experiment with ferrites:
If you take an aircore and put some ferrite in the middle, the inductance increases about 4 fold.
It's not even that bad. Because inductance increases as the square of the number of turns, you don't even need hugely thicker wire to get an air-core as good on resistance as a ferrite.
AFAIK, the only demonstrably non-linear crossover component is ferrite coil. But since most loudspeakers use ferrite magnets too, and hence are glorified ferrite coils, maybe it's not a biggie!
If you take an aircore and put some ferrite in the middle, the inductance increases about 4 fold.
It's not even that bad. Because inductance increases as the square of the number of turns, you don't even need hugely thicker wire to get an air-core as good on resistance as a ferrite.
AFAIK, the only demonstrably non-linear crossover component is ferrite coil. But since most loudspeakers use ferrite magnets too, and hence are glorified ferrite coils, maybe it's not a biggie!
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Hi,
there is absolutely no point in modifying any of the components for a "better" quality ones. This design is 1st order electrical only on midbass, a 2nd order electrical on tweeter though. Asymmetrical type of a filter is not an everyday sight in Dynaudio product but it works well and does the job it was designed for.
I suggest you find a cheap 2 way loudspeaker without a proper crossover network (single cap on tweeter only) and practice skills there. Practically any kind of a budget mini/midi hifi stereo system deploys such speakers.
I am glad so many people are agreeing here. Leave well alone!
To reiterate, Dynaudio (and licencees Morel) take a fairly unique approach to loudspeakers.
Their typical midbasses incorporate a huge 3" dustcap on a 5" cone. This is almost a two-way in itself. Good up to about 3kHz IMO.
They also design tweeters with huge excursion capability. Most regular tweeters would self-destruct at much lower levels on simple crossovers.
What is good about small speakers like this is they very much imitate the human head in size:
This means they do human voices very well. Apparently we have evolved to hear voices for 500,000 years. Musical instruments go back a mere 5,000 years, so we have way to evolve.
Of course you can forget about deep bass. For that you need bigger cabinets and drivers:
YouTube
If Alan Shaw of Harbeth knows what he is talking about, he doesn't worry about using expensive aircoils or MKP capacitors.
He uses cheaper ferrites coils and MKT capacitors:
He does this for a living. And for fun, no doubt.
To reiterate, Dynaudio (and licencees Morel) take a fairly unique approach to loudspeakers.
Their typical midbasses incorporate a huge 3" dustcap on a 5" cone. This is almost a two-way in itself. Good up to about 3kHz IMO.
They also design tweeters with huge excursion capability. Most regular tweeters would self-destruct at much lower levels on simple crossovers.
What is good about small speakers like this is they very much imitate the human head in size:
This means they do human voices very well. Apparently we have evolved to hear voices for 500,000 years. Musical instruments go back a mere 5,000 years, so we have way to evolve.
Of course you can forget about deep bass. For that you need bigger cabinets and drivers:
YouTube
If Alan Shaw of Harbeth knows what he is talking about, he doesn't worry about using expensive aircoils or MKP capacitors.
He uses cheaper ferrites coils and MKT capacitors:
He does this for a living. And for fun, no doubt.
I appreciate all the feedback here, thank you! Such great insight. I think I'm going to heed the general consensus here and leave it alone. I was more or less wanting you experts to have a gander at the crossover and see if there was potentially anything appalling and suggestions on what to do. Doesn't sound like it and it sounds like you have to be very careful and somewhat skilled to mess with a crossover. I'll leave it be. I do appreciate the responses.
@system7 While I wouldn't claim these Audience 42's are in line with the Harbeth's, they do possess an excellent midrange and it's some of what these classics are known for. Construction is also excellent with full 3/4" MDF on all six sides, something you don't see in $850 bookshelves today. The successor to these were the Xcite series and now the Evoke, the Evoke 10, it's direct successor, is now $1500. I digress. They're a classic and was checking to see if there was a way to make them even better. Oh, and one thing I did do though is I applied some sound damping adhesive butyl/bitumin to the crossover board and the binding post plastic cup its tethered to, and small a bit of blu tack to the film cap.
@system7 While I wouldn't claim these Audience 42's are in line with the Harbeth's, they do possess an excellent midrange and it's some of what these classics are known for. Construction is also excellent with full 3/4" MDF on all six sides, something you don't see in $850 bookshelves today. The successor to these were the Xcite series and now the Evoke, the Evoke 10, it's direct successor, is now $1500. I digress. They're a classic and was checking to see if there was a way to make them even better. Oh, and one thing I did do though is I applied some sound damping adhesive butyl/bitumin to the crossover board and the binding post plastic cup its tethered to, and small a bit of blu tack to the film cap.
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In general it's better to use mediocore parts in a well studied and detailed crossover than high end parts in a wild guess. That is what Harbeth does, use cheaper parts, but push them to their quality limits in a very well designed design.
I did rebuild crossovers for a dynaudio speaker (passive BM5A MKI's) in the past, and they were also using cheap MKT and ferrit coils and cement resistors. I replaced the crossover totally with an own design (as the thing was broken due to overpowering the speaker) with jantzen aircoils and Jantzen crossocaps and cement resistors (so no expensive audiophool stuff, just basic good parts), and it sounded a lot better. Only one side was broken, so we could compare with the original (the other side wich was still good). Off course i also did the other side. If i remember it right, the tweeter was a second order, the woofer a first order filter.
But this is a few years ago, while i was starting building crossovers and i was still a very noob on that. With the knowledge i have now, i'll probally do it different. But even a starting amateur could better them. But we did measure the tweeter and woofer seperate (tweeter with an 1uf cap to protect it) and started with that measurements as base with no cost restriction but "keep it reasonable"... Those BM5A's are still in use in an artist studio as studio monitor, next to some new Barefoots he has bought recently.
So if you want to change them, you need to measure the raw drivers in the box and totally redesign the crossover from start. Just swapping parts for "better ones" will probally make it worse as they don't fit the original plan.
I did rebuild crossovers for a dynaudio speaker (passive BM5A MKI's) in the past, and they were also using cheap MKT and ferrit coils and cement resistors. I replaced the crossover totally with an own design (as the thing was broken due to overpowering the speaker) with jantzen aircoils and Jantzen crossocaps and cement resistors (so no expensive audiophool stuff, just basic good parts), and it sounded a lot better. Only one side was broken, so we could compare with the original (the other side wich was still good). Off course i also did the other side. If i remember it right, the tweeter was a second order, the woofer a first order filter.
But this is a few years ago, while i was starting building crossovers and i was still a very noob on that. With the knowledge i have now, i'll probally do it different. But even a starting amateur could better them. But we did measure the tweeter and woofer seperate (tweeter with an 1uf cap to protect it) and started with that measurements as base with no cost restriction but "keep it reasonable"... Those BM5A's are still in use in an artist studio as studio monitor, next to some new Barefoots he has bought recently.
So if you want to change them, you need to measure the raw drivers in the box and totally redesign the crossover from start. Just swapping parts for "better ones" will probally make it worse as they don't fit the original plan.
You know how much is it worth when a diyer does a modification of a commercial loudspeaker in the eyes of a future buyer? Just a little below zero!
Not always, but very often the case, except maybe when the drivers used are very sought after. But does that matter for the OP. I know a lot of people who mod speakers to keep them, because they love them. And if not, they don't take the effort to mod them.
In the head of Allan Shaw
Are the bas reflex port the diaphragm and the lungs hided in the standfloor ???
Alan Shaw eventually understood monney must go the magazins not the filters , we are sure human beings didn't evoluate about their deep nature. Or maybe MKP's are too big for micro shelves speakers ?... Or MKTs being more resisttive at higher frequencies ?
... or maybe consitent enough in the capacitance values needing no sorting out so more afordable than NPE while not aging (best of two world).. and ferit less expensive than copper for the inductors ? ... Maybe he is just a good CEO and know what is a penny !
3000 B.C.... So there were no music instruments before Sumer... Maybe because the first musical instruments shop didn't exist yet ...
One thing we can be sure about, Aberth speakers sound fine
Are the bas reflex port the diaphragm and the lungs hided in the standfloor ???
Alan Shaw eventually understood monney must go the magazins not the filters , we are sure human beings didn't evoluate about their deep nature
. Or maybe MKP's are too big for micro shelves speakers ?... Or MKTs being more resisttive at higher frequencies ?... or maybe consitent enough in the capacitance values needing no sorting out so more afordable than NPE while not aging (best of two world).. and ferit less expensive than copper for the inductors ? ... Maybe he is just a good CEO and know what is a penny !3000 B.C.... So there were no music instruments before Sumer
... Maybe because the first musical instruments shop didn't exist yet ...One thing we can be sure about, Aberth speakers sound fine
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