WIN ISD Pro and multiway design

[MikeCobar]

Thanks, Tony, great info Interesting blog posts, too.

[Stevenn]

Thank you everyone for your replies
As much as I want the best possible sound and most accurate reproduction, I have to compromise somewhere. The speakers are in use every day as they are now part of entertainment system so i cannot have too much downtime, I have a busy new job, two children under 4 and other demands on my time like my other half. I just don't think I have the time to make up components that may not work through my own faulty workmanship.
Thank you Tony for offer of loan of crossovers, might take you up on that.

One qsn - why would ready built Daytona units be inferior to a something home made?
Also prices mentioned don't add up to much savings - $25 x2 for circuit boards, $70 for copper wire plus other components will be pretty much cost of Daytons.....

[wintermute]

Hi Steve, Have a read through this thread Introduction to designing crossovers without measurement and I think you will start to see why doing something yourself should result in something better than buying an off the shelf crossover.

Off the shelf crossovers are usually text book designs that assume they are working into a constant resistance. Speakers do not provide a constant impedance but usually a rising one. See below the attached impedance measurement of my MW144 drivers in their cabinet.

You can see that depending on what the crossover frequency is the resistance is different. a crossover for a particular frequency is dependent on the resistance of the load. so a crossover designed for 4 ohms at 3Khz will be off on my speakers because at 3Khz the impedance has rizen to nearly 6 ohms, additionally it may not attenuate properly due to the constantly rising impedance after that. In my case I simulated to get very close to the desired acoustic response something that a text book design would not have achieved even if I did put in the correct resistance (unless I used a zobel on the drivers which flattens the impedance).

There is also the issue that a text book crossover assumes a completely flat frequency response in the crossover region (and some way either side). In reality the drivers normally have their own rollof and this combines with the electrical rolloff of the crossover to produce the actual acoustic rolloff. This may result in holes or humps in the sound depending on the drivers involved.

Having said all that, I lived with my three ways with off the shelf crossovers, and drivers that didn't match that well for nearly 20 years and was quite happy with them. They still sounded better than most other peoples systems that I heard, It wasn't till I heard something REALLY good that I realized I could do a whole lot better. That was what started me on the quest to make my own from scratch

Tony.

[Stevenn]

Thanks Tony.
Yes this is a good article. Is there one on using a soldering iron?
Another qsn -AllenB says to use manufacturer's driver specs to design crossovers. Wouldn't it be better to use graphs from WinIsd with driver in a cabinet of specific volume?

[wintermute]

I have seen a very good link to a how to solder tutorial but I didn't book mark it Basically I allways clean the leads of the things I am soldering, usually with a bit of 400grit wet and dry, and then wipe off with a cloth soaked in metho.

I did a bit of a google search and found this tutorial which looks pretty good. http://www.elecraft.com/TechNotes/N0...derNotesV6.pdf

Regarding the use of winisd. If you are crossing over in the lower part of the drivers response range then yes using the modeled response for your cabinet is probably best as the manufacturers specs tend to be done with standard baffles and volumes which are not necessarily optimal for the driver, but when looking at higher frequency crossover points (towards the top end of the drivers range) then you definitely want to use the manufacturers specs, or even better your own measurements on your own baffle, as the sim will show this as being totally flat, but the manufacturers spl curves will show that the driver is far from completely flat.

Another aspect which wont be taken into consideration with winisd OR manufacturers specs is baffle step. This can be modeled, but if you have real measurements on the baffle this is best. You can calculate what the baffle step frequency will be with a simple formula. A good explanation of baffle step is here --> Baffle Step Compensation note that Rod presents a line level solution, but it can also be done in the crossover. How much you need is room and placement specific!

I can relate to the issue of time that you mentioned earlier. I have a five year old, she was three when I was getting back into the project. It severely limits the amount of time you have for doing stuff!

I've only designed the crossover for my two way MTM, it was definitely a learning experience! A three way is apparently a lot harder to get right. I'm surprised no one has jumped in and said don't do it yet!! Having been there and done that (and not regretted it) I guess I am a little more on the side of saying if you want to learn then why not jump in.

Anyway do some reading and get a feel for what you are up against and then decide whether you want to spend the cash, or perhaps try something a little easier

Tony.

[Stevenn]

HI
Reference to soldering was tongue in cheek...!
Have located last Jaycar 3 way PCB so they should make life easier.
Where is the best lace to buy inductors etc in Australia? WES Components?
Thanks

[Moondog55]

Speakerbug

[Moondog55]

Steven what drivers have you decided on??
Best advice I was ever given ( and read too ) was to keep the midrange to the widest possible bandwidth and the "telephone" bandwidth 0f 300Hz to 300Hz was going to be my suggested starting point
Buy the best midrange you can afford is also good advice

[wintermute]

sorry I took the soldering comment at face value, you never know the experience level of new members

WES have solen inductors, Speaker Bug linked above by Moondog have jantzen which are very good value for money.

for my prototype I actually got inductors from jaycar (mainly because I could just go and buy them). But they are quite high DCR and I'd go with the janztens next time. The solens are available in larger wire gauges if you need really low DCR.

For caps I can't go past PartsConnexion AXON caps AXON True Cap Metallized Polypropylene Capacitors They are nothing flash, but they are good quality. I bought a range of sizes (since they are so cheap) so that I could experiment. If you keep the weight to below 250g (including packaging) the shipping via post is only around $10.00

Tony.

[Stevenn]

Ok guys you win! I will have a go at my own crossovers.
I love my music and it is a tantalising prospect to think that there may be more to discover in the music that I know well.
Mids are 4 in Peerless 830992. I am guessing moondog means 300Hz - 300 kHz?

Cheers