New FAQ - How to design without measurement gear

[Paul Carmody]

Listen up: this is answer to all the neophyte designers who ask, "I want to design a speaker. What measurement gear will I need to buy?" NONE! Don't buy any. Learn to design a speaker first! Measurement is a whole other can of worms; do not mess with it until you really understand speaker design.

So here's the best step-by-step tutorial I can do of how to use mfr specs (or 3rd party measurements) to "simulate" measurements one can use in the crossover design software of their choice. Best of all, this whole process is FREE. Save your dough for drivers and MDF.

http://sites.google.com/site/undefinition/simulated-measurements

[Brewski]

Re: New FAQ - How to design without measurement gear

Nice write up on the FRD and ZMA file prep Paul. One thing you may want to add is how to invert the baffle step after its been applied in case someone only wants partial or no BSC in their speaker design.

Take it easy
Jay

[robwest]

Re: New FAQ - How to design without measurement gear

Have bookmarked for a good study in the AM. Thanks!

[Wolf]

Re: New FAQ - How to design without measurement gear

Good primer! At least they can create their own files from that. It's also decent enough and not too nitty gritty to where they lose interest.

Well said!
Wolf

[howard]

Re: New FAQ - How to design without measurement gear

Paul,
Wonderful job! I can almost follow it. I appreciate your efforts so much that I am going to name the first speaker that I design the "Carmody". This also lessens my fear of people from Chicago tremendously. Thank you.
Howard

[cuggie]

Re: New FAQ - How to design without measurement gear

I may learn how to do this yet!!!I have just read this one time and already things make a little more sense to me. This one is in "My Really Must Read and Study" list. Your talent for writing so I can begin to understand, and want to learn more is a gift.
Thank You "Muchly"
cuggie

[[email protected]]

Re: New FAQ - How to design without measurement gear

very nice paul. thankyou.

[Paul Carmody]

Re: New FAQ - How to design without measurement gear

Nice write up on the FRD and ZMA file prep Paul. One thing you may want to add is how to invert the baffle step after its been applied in case someone only wants partial or no BSC in their speaker design.

Ah! but that's where the whole "learning process" happens when one experiments with the baffle diffraction simulator.

[diy speaker guy]

Re: New FAQ - How to design without measurement gear

This is another excellently written tutorial, but having seen your other beginner's faq's that's not surprising. I have a couple of small notes regarding steps 3 and 5, since in a small percentage of cases you could end up with an unsuccessful design, but otherwise, this looks like a very valuable resource for beginners.

Step 3 - I would not agree that WinISD should be included in any list of easiest, fastest, most accurate box simulators, as it fails on all 3 counts. In the case of tall boxes (MLTL) or long ports, WinISD comes up far short and can be incredibly inaccurate. A simulator capable of predicting box and port resonances like Hornresp or MJK's Mathcad worksheets (preferred for this job) are far more accurate - and Hornresp is far faster and easier than WinISD too. Using such an advanced program as these makes Step 4 redundant, as it's already been done as part of Step 3.

Step 5 - In the cases where box and/or port resonances cause problems beyond the scope of WinISD, Response Modeller is no better equipped to deal with them. In these cases, the only way to bypass this issue is to create .frd and .zma from the program used in Step 3 and import them into Response Modeller, and then continue with Step 6.

These nitpicks will only affect a small percentage of cases but could result in a great deal of disappointment and no option to fix the situation besides starting again.

I'm not sure if a link would be appropriate, but I would suggest to beginner's that Wolf's 2 crossover blogs would be a natural next "must read" for the beginner who isn't aware of them, since it takes up where this resource leaves off.

Overall, good job.

[whatatrip]

Re: New FAQ - How to design without measurement gear

Very nice Paul. It is very concise and to the point. I didn't check too closely but I did notice the following:

That’s it. I now have 4 files:


DaytonRS150_simmed_minphase.frd


DaytonRS150_simmed_minphase.frd


DaytonRS28a_simmed_minphase.frd


DaytonRS28a_minphase.frd


Shouldn't a couple of those frd extensions be zma extensions?


If a similar FAQ dealing with measuring drivers is a possibility, that would also be great. It seems to me the next logic step is to do your own measuring. Since measuring equipment is relatively inexpensive, anyone who enjoys DIY would surely enjoy seeing the results of "theory" and modeling. It could start with measuring the woofer and using software to build an enclosure, then measuring drivers inside the enclosure and preparing files for crossover software and finally measuring the drivers and xover as a system. There is so much to understand and steps that need to be taken that it is easy to miss something.

[danklugherz]

Re: New FAQ - How to design without measurement gear

Very cool Paul, I'll be using this tutorial next time so I can maybe design my own.
Thank You.:D
Dan

[Wolf]

Re: New FAQ - How to design without measurement gear

Shouldn't a couple of those frd extensions be zma extensions?

Yes- you are correct.
Later,
Wolf

[Jeff B.]

Re: New FAQ - How to design without measurement gear

Nice Job, Paul

[Pete00t]

Re: New FAQ - How to design without measurement gear

Wish this was around 10 months ago. You have definitely made it easier for people to get adjusted to the hobby. Kudos to you Paul.

[mzisserson]

Re: New FAQ - How to design without measurement gear

Way to go Paul!

Before I measured, and I still measure very little, I would set myself up with an L-pad on the tweeter with cap over the series resistor to fine tune voicing. Small changes in these components can make a big sonic difference, and it is easy for a beginner to play with and see the changes in PCD.

I would also use mids that needed a comp series resistor in a 3-way and found it easy to fine tine the mids with small adjustments. The just have to watch the impedance with that one.