Expensive Crossover Parts – Do They Matter?

[captain paranoia]

would tolerance matter less with more resistors in series

Depends on the manufacturing spread.

If the values are random, then the errors will average, but it's quite likely that, in a reel of resistors, adjacent components have the same error, whilst each is still in tolerance. So no averaging of errors.

 

[DonH56]

Polar or not, electrolytics dry out and change value in time. They also have larger tolerances (+/-20%) compared to good film caps. That all that myself can complain about them.

Ceramics, only high K devices behaving as you describe. There are no NP0 ceramics available in the value ranges for crossovers (at least not without a big cost hit) ceramics are out of discussion indeed.

Agree on electrolytics, though 5% and 10% are available (at higher cost, natch). I have also seen more problems with pinholing in electrolytics although that may simply be a function of the dielectric drying out as well. They also tend to have higher tempcos and much higher sensitivity to temperature (reliability/MTBF plummets as they get hotter).

We have had similar issues with low-K RF ceramic caps in RF and wideband decoupling applications but capacitors are not my area of expertise and last time I looked at those was years ago. IIRC the low-K caps also had a greater self-noise (not sure why on that, notes at work and I am home at last -- may have just been the particular ones I measured). Haven't used them for coupling caps in audio. Like you I figured it was a non-issue for crossovers due to the large values needed.

Poor-quality and counterfeit components are getting to be a growing problem.

@Mashcky : Digikey has a number of high-power 3.5-ohm resistors but they are expensive: https://www.digikey.com/products/en...036&quantity=&ColumnSort=0&page=1&pageSize=25 I'd look at some decent non-inductive or wirewound 5 W resistors in higher values an parallel them as others have suggested.

Parts Express has quite a selection: https://www.parts-express.com/searc...P_Searchable","1")]&Ntt=resistors*&PortalID=1

HTH - Don

 

[Cbdb2]

The only reason was cost and a busier crossover board. I thought about two 7 ohm resistors but that doubled the cost. I ultimately found some that were close enough to 3.5 ohm (3.6) and was comfortable enough that it would not make a difference in sound.

As an aside – would tolerance matter less with more resistors in series? My understanding is that tolerance is just margin of error, so the more resistors you have, the closer you get to their expected value even if each individual tolerance is high.

You can always tweak those resistor values by adding a small resistor. As in a 126 ohm ( just needs to be close ) in parralel with that 3.6 gives you 3.5 ohms, and 1/2 watt resistor will do it.

Otherwise all good advice, the only other thing I would add is to stay away from iron core inductors, if size and cost arent a problem.

 

[SIY]

A highly relevant and short discussion of the impact of crossover component quality and its impact on speaker audio quality by an experienced speaker design engineer is here

There's a mix of correct stuff and absolute nonsense. Take this with many grains of salt- remember, he IS selling something.

 

[redboat77]

There's a mix of correct stuff and absolute nonsense. Take this with many grains of salt- remember, he IS selling something.

Please educate us further. Which parts are correct and which are absolute nonsense?

 

[SIY]

Please educate us further. Which parts are correct and which are absolute nonsense?

Ask yourself with each assertion, "How do you know that? Does data support this? What are the assumptions? Have they been validated?" Then you can start sorting it out for yourself.

 

[ctrl]

There is a lot to read about resistors and capacitors here:

Capacitor upgrade in crossover - Is it audible?
Part 2
Part 3

Differences between sand-cast and low-inductance resistors


Danny always refers to "smear" when looking at the coils, now this is not a term that is technically in use

The most important thing with core coils, as Danny also mentions, is the saturation limit. Once this is reached, the tonal effect is clearly audible.

If you stay well below the saturation limit of the core coil when listening to music, you will not suffer any disadvantages from using core coils, since the distortion produced is usually well below the distortion of the drivers.
Anyone listening at "normal" volume should not be able to drive a reasonably sized core coil into saturation.

I have described this in more detail and with examples of core coil measurements here.

Within the different types of core coils there are still clear differences in quality - this is also mentioned in the video. So it really depends on the individual case.

But as @amirm's distortion measurements of inexpensive speakers show us again and again, the distortions generated by the core coils tend not to play a major role - otherwise there would be no inexpensive speakers with low harmonic distortions.

What Danny doesn't directly address is the big advantage of using core coils - the significantly lower DC resistance (at a comparable price of core coil and air core coil), which leads to a noticeably higher sound pressure in the low frequency range (the area in which core coils are normally used).

If after replacing a core coil with an air core coil, a difference is perceived at normal listening volume, the difference in DC resistance is likely to be the cause - the air core coil reduces the sound pressure in the low frequency range somewhat (if the resistance of the air core coil is higher).

 

[Killingbeans]

I've never wanted to double like a post so much before in my life

 

[abdo123]

From my little understanding of electrical engineering. Not at all. Unless the cheap equivalent is so poor that it would make the filters inaccurate.

The important part of the signal is before (or at) amplification. As any noise, distortion or any shenanigans would be amplified immensely and they would be audible (to an extent).

but after amplification it doesn’t matter that much.

 

[Speedskater]

Please educate us further. Which parts are correct and which are absolute nonsense?

Is there a transcript of the 30 minute video?
It's not fun correcting video errors, without a text of the program.

 

[Cbdb2]

A highly relevant and short discussion of the impact of crossover component quality and its impact on speaker audio quality by an experienced speaker design engineer is here

You mean an experienced shill. I would take very little of that as truth.

 

[redboat77]

You mean an experienced shill. I would take very little of that as truth.

Deleted. But at least the post generated some illuminating responses.

 

[phoenixdogfan]

The Vishays are also available as non-inductive (NS). If the resistor is being used as a shunt rather than series, the inductance is unlikely to cause a significant issue.

More generally, a LOT of "premium" crossover parts will actually have inferior performance. Capacitors and inductors from boutiques claiming "hand wound" will not be as tight and consistent as mass produced parts from mainstream suppliers. As well, a competent crossover design will take into account the DCR of inductors and ESR of caps, so if you swap them for components having lower DCR or ESR, you will degrade the performance.

Capacitors especially seem to draw the mystics like turds draw flies.

Kinda like how FPGAs are claimed to be superior over commercially produced DAC chips, but aren't.

 

[randing]

This is a helpful thread. Passive crossovers are still more of an art than a science at my current level of understanding, been trying to make sense of how much difference going up or down tenths of a microHenry (due to inductor cost/availability) will make on a tweeter. Thank you for the notes, @SIY.