Axiom Home Page Forums General Discussion Technical Questions Crossover design

Does anyone know how critical it is to maintain the exact components in a crossover design?

I ask because I am about to build some speakers and will likely sustitute higher tolerance parts than were spec'd in the original design. ie. inductors with lower resistance. Resistors with lower inductance etc. than designer spec'd parts.

I have an email into the designer as well but thought I would ask the void for input.

Hi Serenity,

Unless you have a technical electronics or engineering degree and the electronic gear to plug in different component values and graph the changes in frequency response and crossover slopes, it's impossible to estimate what effects the substitution of different components will have in a particular crossover design.

I recall watching Ian test different values of crossover components in tweaking the design of an Axiom speaker, and subtle changes in the component values gave the speaker an entirely different midrange response when the speaker was measured and then tested in double-blind listening tests.

The speaker might have been the early M80ti, whose midrange response I was highly critical of (edgy and sibilant on female vocals and brass instruments) and wanted him to change, which he did.

Good luck (and you'll need it) on the home-built speaker design.

Alan

Thanks!

I'm not going to stray from the prescribed values, just go from 5% to 1 or 2% parts and larger AWG size on the inductors. After some poking around I see that parts costs escalate quickly, so I'm not going crazy with Mundorf Maximizer Ultimate Sunshine....

Solen Fast Caps (PB, SB in tweeter CCT), Erse Inductors 16awg, Mills Resistors in parallel to double power handling and further tighten tolerances. Pretty much defacto parts express stuff for mid to higher range builds. High value for $ stuff. Won't be cheap, but wont be silly either. Or is it..... Total estimated cost for 3 towers $529 before shipping. Yikes!

The benefits of tighter component tolerances increase with filter order. A third order filter would benefit greatly but a first order won't.

My advice is to build the kit. Once you've done that, then you can experiment. Try to get the ideal parts list from the designer. The ideal parts list comes from calculated values. The first thing to do is wind your own inductors. These are the most non-ideal component. Then switch to non electrolytic caps.

Alan is right in that a crossover is complex business. I know because I've been involved in the design of passive and active filters - not for loudspeakers. The passive crossover for a loudspeaker incolves a lot of mental masturbation particularly for second and higher orders. Controlling the voice coil via passive means when it's impedance changes as a function of temperature, altitude and input power is darned near impossible.

Hence why active crossovers are the only way to go and that's where the LFR needs to go next.

My understanding with active is you need to handle each transducer seperately, including amplification. Too expensive for a 3 channel setup with 3 way towers. I am building external crossover boxes so the driver leads are available for further adventures. Options.

Separate amps indeed but it looks like you are all set for that .

External crossovers also eliminate any concern from magnetic coupling from the drivers including modulation from enclosure vibrations.

I really butchered the spelling on my second last post. Phones and larger fingers don't work well together.

Over $500 for crossover parts?

You can get an excellent digital crossover for far less than that. You'll need some amps though $$.

Where do you get the digital X-over from?

Interestingly enough my Onk has two separate outputs per channel for the front. One of the outputs is for bass and mid-range and the other is for the tweeter. You can configure your own X-over in the setup. I've never tried it but have always wondered how well it works.

MiniDSP, Behringer DCX2496, I'm not sure if BBE still makes one or not. The MiniDSP is supposed to be a really good unit.

Mini dsp 10x10 and 10 amp channels plus cables. I'll take $529.

You can use software like X-Over pro which is rudimentary compared to LMS plus many others that will graphically show what the changes would be . In the end is comes down to measuring with a good microphone out in the middle of your yard on a quiet day using software like REW to get a desecent frequency response. Then you go inside whre your room screws with everything you ever knew about sound then back to the software change some components on the crossover, back outside when the right conditions are met run tests, rinse and repeat. OR just build the crossover as it was designed and enjoy. Both ways are perfectly acceptable.

Designer votes "better" is no harm, but not audibly better likely. I asked him to specify components for me as I'm not doing the crossover as part of my order. Pressing my luck! But he is very nice.

He likes the Mills resistor choice. Decent! They are cheap comparatively speaking vs caps....

I think i read somewhere, (loudspeaker cook book components within 10%) Never wrong to go with better quality capacitors or wire wound vs iron core inductors. In the end no way to know if it makes a diff or not unless you build both but i went with quality parts most of which came from Solen.ca There seems to be no limit on what you can spend on crossover parts except when the money runs out.

I also used Parts Conexxion they have good quality parts .

Hey hey!

Solen has been solid for me so far. Excellent service. I have ordered my woofers, mids and tweets through their online store. The midrange units had production run issues and they have been on backorder since August last year.... I didnt know this before ordering. They called me saying my order couldnt be completed but once they found out I was already 4 sheets of MDF deep they called around and sourced me some from another source (a competitor I think) at no extra cost. Tops!

yup they are great, bought an amp for a sub and it started acting weird wouldnt work unless i put pressure on the polarity switch. Sent it back, on my dime but they sent a new one on their dime cant ask for much more given where i live. I bought Axon caps from parts conexxion and few other things they are aces as well imho.

Check them out , just for fun some of the prices are insane .

I checked them out. Hilarious. I like how the higher end capacitors start to resemble some steampunk coaster shaped artifacts you'd go searching for in a video game like Bioshock. Awesome. Beeswax has power!!!!!

After speaking to the designer a little more I get where Alan and Mojo are coming from a little better. He has a preference for certain parts over others, but said as long as the values are maintained that's the biggest part.... at first. Then when I pressed my luck he started to share some alchemy that leads to the whole 1+1=3 we all strive for. Sure, more expensive parts may be a 4, but I'd rather pay for combining two 1s to get closer. It turns out using certain combinations of parts yields better performance -for like a buck more. Kinda like tweaking your Honda. Not gonna make it a racecar, but for a few bucks more why not.

I fully understand how DIY speaker building becomes a hobby unto itself. So many variables and rabbit holes to chase through. And the $ goes as far as you wanna take it!

Heres hopin they sound good to you in the end. I have a tin ear, i know what i like when i hear it but fine tuning a speaker not something i have the patience for. Like everything in audio, there are diminishing returns as more money is spent. Keep us posted with some pics along the way.