Crossover Component Recommendations

[SmellyCroc]

Hi,

I'm diving into the world of DIY speakers and would appreciate some guidance regarding crossover components.
I've worked with electronic components in the past (industrial level) and am comfortable with the how and why, but audio seems a minefield of snake oil and profligacy, and I find myself a bit lost! I did swing by another diy forum but, despite some helpful folks, it felt quite cliquey and I'm not convinced I would have received the objective advice I'm after.

So, what manufacturers and specs should I be looking at if I want decent price/quality/performance? I'm in the UK, so local supply preferred, but it's not the end of the world if I must ship.

It's a long-term project (getting drivers is priority and currently have the woofers and mids) and the design is open source: SB Aacoustics Sasandu TX (The CX schematic is attached)


Thank you,.

SC

 

[Grotti]

Hi,

I'm diving into the world of DIY speakers and would appreciate some guidance regarding crossover components.
I've worked with electronic components in the past (industrial level) and am comfortable with the how and why, but audio seems a minefield of snake oil and profligacy, and I find myself a bit lost! I did swing by another diy forum but, despite some helpful folks, it felt quite cliquey and I'm not convinced I would have received the objective advice I'm after.

So, what manufacturers and specs should I be looking at if I want decent price/quality/performance? I'm in the UK, so local supply preferred, but it's not the end of the world if I must ship.

It's a long-term project (getting drivers is priority and currently have the woofers and mids) and the design is open source: SB Aacoustics Sasandu TX (The CX schematic is attached)


Thank you,.

SC

Welcome at ASR.

Before others chime in to go into detail: i could not find any reliable measurements of this particular speaker. Without measurements it is not certain that it can be equalized properly to your room or needs. Have you had the opportunity to listen to the speakers yet? I know someone who burned about 5000 € for a diy kit, which did sound horrible to him and which no modification could rescue.

Regarding the crossover parts: use air coils wherever possible and don't fall for fancy "high end" capacitors...i used Solen caps (400V) in nearly everything i have build and i never noticed a difference for the better when i tried something snake oilish (silver oil caps etc).

All the best for your project and if you don't mind: share the results (and measurements?) with us...

 

[levimax]

Hello, can't help much with UK supply but in the US these are some of the better places to source components https://www.parts-express.com/, https://www.mouser.com/, https://www.digikey.com/.

As mentioned you are getting into an area filled with snake oil when it comes to crossover parts especially the capacitors. Looking at the schematic you have some high value high voltage capacitors called out which are going to be expensive especially if you go with film capacitors. There is a strong objective argument that you can use bi-directional electrolytic capacitors instead of film and save a lot of money with no audible impact but you will not hear that from the "everything matters" subjectivist crowd. Not sure your budget or priorities but if an experiment and cost matters I would use electrolytic for the high value caps high voltage caps and film for low value low voltage caps. If this project is more a "master piece" I would use standard quality film caps from a good manufacturer. No matter what avoid the expensive "audiophile" film caps as there is no objective evidence they perform better and some evidence that they are actually worse.

One other thing I would consider since this is a DIY project in 2023 would be to use active crossover with a multi-channel amp. It will be cheaper (especially if you use film caps) with the potential for higher performance. You would have to put the schematic into a CAD program to figure out the curves as a starting point but with active and a free program like REW and a microphone you can fine tune things and most likely exceed the performance of the passive crossover. Of course there is a learning curve.

Have fun!

 

[tinnitus]

I prefer digital XOs

 

[DVDdoug]

The "specs" are fairly straightforward. You don't need exotic "audiophile" components.

Capacitors are rated for capacitance (usually uF) and voltage. The voltage is the maximum, so it's OK to use 400V capacitors, etc.

Inductors have an inductance rating (usually mH) and a current rating. Again, the current is the maximum allowed.

Resistors have a resistance and power maximum rating. Resistors should normally be "derated" so you should use a resistor with at least twice the power that you really need. (There is a voltage rating but it will be more than 1000V so you don't have to worry about it... You'll never have 1000V and at 1000V you'll exceed the wattage rating and burn it up.)

All parts also have a tolerance. (A 5% capacitor is within 5% of it's rated capacitance).

Film capacitors might be better than non-polarized electrolytics. Do NOT use regular-everyday polarized electrolytic capacitors. Non-polarized electrolytics are a "specialty item" and I've only seen them used in crossovers. (Only electrolytic and tantalum capacitors are polarized so it's not an issue with other types.)

You should know (or you can research) Ohm's Law which is the relationship between voltage between, resistance (or impedance) and current. and related formulas.

And you should know the power formulas so you can calculate the voltage & current requirements, and power requirements for any resistors.

 

[Ken Tajalli]

Amplifier valve kits, HIFI pre-amplifiers, speaker kits, AMP Parts, upgrade components | Hifi Collective

Hificollective One stop for hifi kits, components hi-fi diyers Build you own valve amps from scratch, dabble in speaker design, a component tweaker or a true beginner.

www.hificollective.co.uk

Edit: I forgot, there is also wilmslow audio! they go back 40 years +

Speaker Repair, Speaker Kits, Loudspeaker Repair, Kits and Drive Units, Subwoofer Amplifier Kit

Wilmslow Audio provide speaker repair services, speaker kits, a range of subwoofer amplifier kit products and loudspeaker kits, loudspeaker drive units and loudspeaker repair services.

wilmslowaudio.co.uk

I glanced at your circuit, 300uF caps?? what are they, DC blockers?
Anyways, the above link is your one-stop shop, not cheap, but they do have quality stuff.

 

[solderdude]

The 300uF are part of a series filter designed to compensate for the impedance hump of the used transducers so the filter works more accurately as if the speaker does not have a resonance frequency.

 

[Ken Tajalli]

The 300uF are part of a series filter designed to compensate for the impedance hump of the used transducers so the filter works more accurately as if the speaker does not have a resonance frequency.

If you say so.
I bet if you replace them with a piece of wire, no-one can tell in a blind test.
Something smells off, if you need 900uF capacitance in a crossover circuit, but you know better.
Just a guess.

 

[voodooless]

If you say so.

That is what it should do in theory..

I bet if you replace them with a piece of wire, no-one can tell in a blind test.
Something smells off, if you need 900uF capacitance in a crossover circuit, but you know better.
Just a guess.

Yes, it it curious. The crossover is at 400 Hz. Why would you need to linearize the impedance peak of the midrange fs? That’s way lower down.

 

[solderdude]

Willing to bet it could be measurable and audible as leaving them out or shorting them will change the entire filter.

 

[solderdude]

That is what it should do in theory..

Yes, it it curious. The crossover is at 400 Hz. Why would you need to linearize the impedance peak of the midrange fs? That’s way lower down.

900uF and 10mH = 53Hz
fs of the connected speaker is 29Hz but that could alter depending on the enclosure.
Maybe the goal is to provide a better load for the connected amp.

 

[voodooless]

900uF and 10mH = 53Hz
fs of the connected speaker is 29Hz but that could alter depending on the enclosure.
Maybe the goal is to provide a better load for the connected amp.

A small closed box would raise the impedance peak. Stil, 53 Hz is a long way off from 400 Hz.

 

[solderdude]

When the goal is to ensure a nice near Ohmic load to the high pass then that would be a good reason to use such a series filter in parallel of a speaker when the Q of the woofer is high.
I would expect the designer measured the crap out of it before using expensive parts that do not have any influence.

 

[voodooless]

When the goal is to ensure a nice near Ohmic load to the amp then that would be a good reason to use such a series filter in parallel of a speaker.

Wouldn’t the highpass will already take care of that?

 

[solderdude]

The designer made similar compensation circuits for all the drivers.
It would be daft to include them when it would not matter nor do anything beneficial.
Arguably the filter for the 2 woofers would benefit most (and prevent an impedance hump)

 

[voodooless]

It would be daft to include them when it would not matter nor do anything beneficial.

Well, yes! But since when stopped that anyone from doing it anyway?

It should be easy to simulate what these things do. Given the cost of these large caps, that’s definitely worth doing.

 

[Ken Tajalli]

900uF and 10mH = 53Hz
fs of the connected speaker is 29Hz but that could alter depending on the enclosure.
Maybe the goal is to provide a better load for the connected amp.

Controlling a 50Hz possible glitch on a midrange driver, at 1/8th of the crossover frequency, is going to be audible.
Oh well.
@voodooless
Non-pol caps are cheap anyways, about a few pounds each.
It is those large plastic caps that are expensive.

 

[voodooless]

@voodooless
Non-pol caps are cheap anyways, about a few pounds each.
It is those large plastic caps that are expensive.

I would not recommend those for these values indeed. Stil, bipolar caps aren’t exactly super cheap with those voltages.

 

[Wolf]

To the OP, since you are in Europe, basic polypropylene capacitors are the best angle.
I suggest Audyn Q4, Jantzen CrossCap, or ClarityCap PX. Try to stay away from cored inductors if possible, but in the woofer lowpass or much larger values, the steel laminate types can be more cost effective. Using nonpolar electrolytic capacitors in ultra large values and/or shunt to ground circuits seem to be their best use, however, I would avoid them in series with drivers if possible due to the higher insertion losses due to their higher ESR.

Normally large LCR filters across woofers like that are for 2 reasons:
- to reduce a resonance in the impedance
- to reduce a peak in the frequency response

The case listed here is presented to a 4 ohm load, and is likely to suppress the frequency of resonance of the woofers in the box as it increases from free-air spec. In cases where the magnitude of this impedance resonance is really large, and if using a low DCR coil in the lowpass, this will make a bump appear in the woofers frequency response passband. The notch reduces the magnitude of the in box resonance, and the bump flattens out.

This is not the only way to do this, but it is the most effective. It just happens to use large parts values. Just because values are large does not make them unnecessary. I have used 600uF, 10mH, and 50 ohms in circuits before.

 

[SmellyCroc]

Hello, can't help much with UK supply but in the US these are some of the better places to source components https://www.parts-express.com/, https://www.mouser.com/, https://www.digikey.com/.

As mentioned you are getting into an area filled with snake oil when it comes to crossover parts especially the capacitors. Looking at the schematic you have some high value high voltage capacitors called out which are going to be expensive especially if you go with film capacitors. There is a strong objective argument that you can use bi-directional electrolytic capacitors instead of film and save a lot of money with no audible impact but you will not hear that from the "everything matters" subjectivist crowd. Not sure your budget or priorities but if an experiment and cost matters I would use electrolytic for the high value caps high voltage caps and film for low value low voltage caps. If this project is more a "master piece" I would use standard quality film caps from a good manufacturer. No matter what avoid the expensive "audiophile" film caps as there is no objective evidence they perform better and some evidence that they are actually worse.

One other thing I would consider since this is a DIY project in 2023 would be to use active crossover with a multi-channel amp. It will be cheaper (especially if you use film caps) with the potential for higher performance. You would have to put the schematic into a CAD program to figure out the curves as a starting point but with active and a free program like REW and a microphone you can fine tune things and most likely exceed the performance of the passive crossover. Of course there is a learning curve.

Have fun!

Hi, thanks for the reply.

Digital XO sounded interesting, so I've downloaded VituixCAD and am going through the process of learning that.
Im in no rush and its good to learn new skills!

Thank you