Modifying Crossovers

@jaytor, understood, thanks.

@carlsbad2, nice looking XO you put together, congratulations. Are those Path resistors you have there and did you compare with any others? There is also what appears to be maybe a Mundorf resistor mounted on a heatsink. If so I think it is a Vishay device and adopted by Mundorf. I found the same thing under the brand Powertron and is cheaper. I find it clean, very dynamic and open and use it always with it's heatsink to avoid thermal compression. Also are those 2 caps next to the low frequency inductor Duelund bypass caps?

Regarding your choice of Duelund in cotton for internal wiring may I suggest you consider solid OCC copper in PTFE insulation instead. It's more expensive but in keeping with the other components you have in the XO. I normally remove any push on connectors and solder, vastly and consistently better. Solid core wire needs to be anchored close to the terminal to prevent fatigue. Do not twist + and - just keep about 1" spacing between. To take it up a level avoid using the speaker terminals as a connection. I do this on my speakers' and amplifier terminals. I bring the wires from XO outside the box and terminate with pure copper FUREZ spades. I use identical spades on the speaker cables also terminated with FUREZ spades and place them back to back into the terminals that now merely act as a clamp. Ideally removing those huge lumps of dubious quality binding posts, finding that a non-metallic way of clamping is better still.

Next step would be to have the XOs outside the box.

There seems to be a lot of advice from people who have little to zero experience with XOs and even display resentment that somebody should have the temerity to suggest they could improve on what the OEM did.

The idea that if better parts were needed then the designer would have used them, is the result of not properly thinking things through and finding comfort in the dubious knowledge that their speaker is the best it can be. Really? There is very little that can't be improved with knowledge and some cash!

Caps are, for some strange reason, thought by most to be where the performance difference occurs so I will mention them in my example, but truth is all the components will have a sound and contribute to the end result.

OK, lets take a manufacturer who intends to produce 500 pairs of a certain speaker, and lets take the series cap for the tweeter. A cap in this position that will do the job can be found for $1 or less and will provide an acceptable frequency response.  The owner of a pair of these hypothetical speakers could replace cheapo cap with a $20 cap of identical value, which will provide the same identical frequency response as the cheap cap, and hear a nice improvement. So for $40 he could enjoy an upgrade on both speakers about equal to a $200 interconnect. (I'm generalising here)  

So why you ask, doesn't the manufacturer do this? Think about the cost!

By just looking at the tweeter caps and nothing else he would have to outlay $20 x 1000 = $20000

Everything matters in audio and in a XO which is widely accepted as the heart of a speaker it matters lots. For those that ask: how can a cap or whatever improve the sound, the answer is, it can't. What we are trying to do here is do the least damage to the signal.

@carlsbad2, with regard to the Duelund bypass caps, I'm curious to know if you listened to your system before installing the bypass and what change you heard after, also which ones did you chose?

@jaytor, very nice set up you have there and I notice in the photo you provided of your XO that you too appear to use Duelund bypass caps. As there are a variety of Duelunds caps I'm asking because I wish to buy once and cry once 🙂

@carlsbad2, Hey Jerry, thanks for the generous offer. I have a lot of experience designing and modifying XOs. Have been doing this for what seems like forever and have a speaker design of mine about to go into production. The person who asked me to design him a small bookshelf speaker was a customer of mine and now has a retail outlet. He has the prototype but seems to have a problem finding someone to build a good quality veneered box.

After designing the XO I spent some considerable time choosing components and it was then that I settled on the Powertron resistor. Reverting back to Mills, paralleled Kiwame, Mundorf and some others was a big disappointment. I did not have a chance to try Duelund nor Path resistors as it was at this time that I was preparing to leave South Africa to move overseas.

I have found some rather expensive speakers that look expensive and fitted with beautifully machined spikes to give the impression of great care and engineering chops, but have cheaped out on the XO components which are hidden from view. Push-on connectors are used on the internal wiring to speed up assembly and other sound limiting short cuts are taken. All this cost saving is doing the resultant sound no favours.

Something mostly overlooked either from ignorance or deliberate acceptance is the orientation of the inductors. If two coils are close to each other there will be coupling, this is how transformers work, where they talk to each other causing congestion and smear. Keeping them far apart helps but of course will require a larger platform causing even more problems. Another reason that the coils are not optimally aligned is because one of them needs to be mounted, not lying flat, but upright on the rounded part which makes mounting it more difficult and time consuming.

If they are mounted correctly then they can be placed close to each other with virtually zero coupling. This happens when they are positioned as two links of a chain would lie.

Then there is the internal wiring, nasty sand cast resistors and the almost exclusive use of PCBs. Yes, there is much that can be improved. We are not talking about redesigning the XO circuit but improving what is there by replacing components with same value but better parts.

When I work on optimising the XO I endeavor to remove any terminals using brass. Those great looking chunky speaker terminals are bad news. Usually the brass, IACS about 27%, is first plated with nickel, IACS about 24%, which polishes to a high finish, and then gold plated. The polished nickel allows for a very fine looking and attractive finish. So, many dissimilar metals playing havoc with your precious audio signal. The push-ons are also brass!

@simonmoon,  good post.

As you describe, results of sensible XO mods I've done have always improved the  sound, ranging from a clear and easily heard upgrade to the astonishing.