Questions From a Speaker Measuring Noob.

[DIYNut42]

Hey guys. I'm putting together all the things I need for a decent measurement set-up, but I have a few questions regarding a few of the components. I would also appreciate any suggestions as to other items that might come in handy.

First off, here is what I have so far:

Dell Inspiron E1505 with Windows Vista Home Premium. An older laptop, but after a recent RAM upgrade, this thing is still going strong!

Laptop's internal sound management is via SigmaTel High Definition Audio. Only output is the normal 3.5mm (1/8") headphone jack.

Dayton EMM-6 Mic (currently uncalibrated, but I found the cal file on PE's site for mine)

Blue Icicle

Dayton 25' Mic Cable (on the way from PE as we speak)

So far I've downloaded both HOLM and REW. Another forum member suggested that REW would be easier to implement for a measuring noob.

The only amp I have at the moment to power the speakers is an old Fisher 5 channel receiver. This is the receiver I have set aside to do some testing. It's a little older (mid 90's model), but it puts out clean sound at 100wpc. Plus it has manually adjustable EQ level knobs across most of the band. Not sure if that would come in handy for measurement though. For now can I just use one of the L or R channels for a signal? I have a nice Belkin 3.5mm to RCA cable for stereo output from my laptop, and the receiver has more than one 2 channel stereo mode. I also have a pretty solid kit for a 68wpc x 2 LM3886TF chip amp, but I haven't had time to build it just yet.

As far as my questions go, these are ones I searched for but couldn't find answers to:

At what point in setting up everything do I use my mic calibration file, how do I calibrate it, and what is used to calibrate it? I know some have the better Cross Spectrum calibrated EMM-6. For now, the current Dayton cal file will suit my needs, but does Cross Spectrum offer services to calibrate a mic if you send it to them?

When measuring I will have 3 different volume levels to consider. My laptops volume, the amps volume, and the gain on my Blue Icicle. What is the norm setting for all these during measurement? I know there are ways to adjust the dB level in the measurement software, but is there a general rule of thumb for the hardware?

Lets say in a two way speaker, I've noticed that some will send a signal to the woofer, then the tweeter and measure them separately. Others will send a signal to the woofer and tweeter at the same time wired in parallel. Is there a general rule of thumb for these different ways of measuring? Or is it just preference of the user coming in to play?

That's all I have for now. Any advice or feedback is appreciated. Hoping to learn more as time goes. I have all kinds of drivers sitting around now, and plenty of XO components. So this winter I plan on having some measuring fun in seeing what all kinds of crazy stuff I can come up with. :D

Thanks!


Ryan

[rpb]

Re: Questions From a Speaker Measuring Noob.

It's easier than you make it sound. Any old amp will probably do fine. Measure drivers in any order, or combination you want. What you don't know now, you will figure out pretty easily. Even when you do something a little wrong, you will have fun. I suggest using HOLM.

http://techtalk.parts-express.com/showthread.php?229930-A-HOLM-starter-guide&highlight=HolmImpulse

[DIYNut42]

Re: Questions From a Speaker Measuring Noob.

It's easier than you make it sound. Any old amp will probably do fine. Measure drivers in any order, or combination you want. What you don't know now, you will figure out pretty easily. Even when you do something a little wrong, you will have fun. I suggest using HOLM.

http://techtalk.parts-express.com/sh...ht=HolmImpulse

Thanks for the mind easing words. After playing with HOLM and REW's options, it looks fairly self explanatory. I'm sure little questions will pop up along the way. What about the calibration of my mic? I've searched the forums, but don't see any tips or instructions for a "how-to".

[lhwidget]

Re: Questions From a Speaker Measuring Noob.

I know this isn't one of your questions, but it is something you should think about; Does your test amp have a digital processor built in? I started with an old Sony 5.1 amp and it took me a year to realize that the brick wall stop in frequency response at 22000 Hz was affecting my tweeter measurements. If you can't find a pure analog signal path in your amp, the inability to measure the tweeter's high frequency response will cost you accuracy in the tweeter's phase measurement. This can be serious enough to cause problems in XO designs at 3500 Hz and higher, not so bad at 2000 Hz and below.

Herb at Cross Spectrum will need your mic, he will measure its actual frequency response, send the mic and custom cal file back to you. This file is used by the software to take the mic's frequency response out of the measurements.

The software will usually guide you in setting the sound card's volume (usually about 90%). The Amp should be set to a volume low enough to avoid distortion in itself and the driver being tested. Start at a low amp volume setting. If your measurements look bad, increase the amp's volume until you are above the "noise floor" of the equipment. Usually, 1/4 to 1/2 volume on the amp. Hopefully Bill Fitzmaurice will chime in on the Blue Icicle, he uses one. It should probably be set around 90% also.

When designing XOs, measure each driver by itself. Most start with the tweeter, on axis, then measure the mid/woofer from the same mic position. Typical measurements are taken at 1 meter, with gating times of 500 to 200 ms. Use a gate time short enough to stop the measurement before the first reflection arrives. You can usually see this as a second smaller impulse showing up after the initial impulse in the measuring software's impulse response window. Take the phase and freq response files into Jeff's PCD spreadsheet and go to work on the XO.

Use Holm for individual driver measurements for XO design, Rew for looking at a finished speaker system's response in-room.

[DIYNut42]

Re: Questions From a Speaker Measuring Noob.

Thanks. I think that amp has a digital processor, but it can be shut off via some of the settings. I guess I will find out by trial and error eventually. I plan on putting together that chip amp soon, so that will be a way around that problem all together hopefully.

When you are talking about "the software" using the calibration file, are you talking about HOLM and REW?

I think I get what you're saying about gated measurements. If I'm measuring in a room, a gated measurement will help to avoid reflections like floor bounce or other reflections caused by the rooms characteristics? As long as the weather is nice I'm going to try the majority of my measuring outside.

[rpb]

Re: Questions From a Speaker Measuring Noob.

Outdoor measurements are a little better, and a fun way to meet neighbors. On a nice day, it can be hard to see the monitor screen though. For 2-ways, indoor measurements
are easily sufficient. Three-ways can also be done indoors, but you have to work a little harder interpreting what you measure. If you have ceilings over 8 feet high, then you might do all
your measurements indoors if furniture, and family permit it. If you want to make a calibration file for a mic for
use with HOLM, it is pretty easy. I think I covered that in the guide. You need a reference, or some way of knowing how much correction is needed. A lot depends on how you plan
to use the measurements. I would suggest trying HOLM using what you have, and simply learn as you go. In 2 weeks, you will be answering these types of questions on the forum.
My mic is not calibrated, and my PC didn't need any adjustment when I checked
it with the loop-back test.

[jhollander]

Re: Questions From a Speaker Measuring Noob.

I used a Dell and the Blue Icicle and could not get it to work. You need separate mic inputs and speaker/ headphone outputs. I can’t recall if the Icicle has phantom power for the mic. I ended up using the cheap M-audio fast track external usb sound card/ box.

Your calibration file gets loaded into the measurement software. If you have the calibration file then it’s calibrated once the file is loaded. IMO extra calibration of you mic is not going to improve your results.

+1 on the shaping circuit problems of some amplifiers. Depending on the software you can use a voltage probe to test the amplifier. I’ve not tried it, I learned by error.

The beny of the m-audio fast track is I can see when I’m clipping the mic. Typical I’ll mark all the volume/ gain setting and use those.

There are multiple measuring methods depending if you want to derive the z coordinates. Search on off-sets in tech talk. I don’t have my links avail but can send you some later.

Dats is a valuable tool if you are going to spend money

[DIYNut42]

Re: Questions From a Speaker Measuring Noob.

Thanks for the input guys. I haven't tried out the blue icicle with my dell yet, so I guess I will see what happens. When Im on it later I will see if it has a USB option in the advanced settings. I already have DATS, and I could have swore I saw a USB device option for recording when I was adjusting the advanced settings for DATS. I may invest in a Fast Track later on either way.

[DIYNut42]

Re: Questions From a Speaker Measuring Noob.

Also, rpb, I haven't read all of your thread yet, but it's already been a help in answering some of my questions so far. Thanks for taking the time to put that together.

As far as the Z offsets, I've heard others say that when you measure using HOLM, all the Z offsets are kind of baked into the response when measuring in-box. Is that true? I will do some forum searches and see what else I can find.

*UPDATE - I just plugged the Blue Icicle in. Took about 10 seconds to instal drivers, and it recognizes it fine.

[blackbox]

Re: Questions From a Speaker Measuring Noob.

I haven't yet read through this whole thread. But this is my advice for anyone wanting to learn to measure drivers and learn to build x-overs. First download ARTA. Then go to https://sites.google.com/site/froste...ta-information and follow the advice there on how to use it..ARTA is really really easy to learn. I've used SW, SE and have played with HOLM and I think ARTA is by far the better software for anyone just starting out.
Now that you have your measurements go to http://www.rjbaudio.com/Audiofiles/SWtutorial.html and learn how to import those measurements into the easy to learn Speakerworkshop cross-over design section. You will be making x-overs in no time.
In fact the best advice I can give ANYONE to understand how cross-overs are made is to go to this SW tutorial ( there are frd and zma files listed on Roman's site) and learn to use it. I was lost for YEARS until I did this one simple little thing....learn to use the SW x-over section!!!!!!!!!! trust me on this.

[DIYNut42]

Re: Questions From a Speaker Measuring Noob.

I haven't gotten around to downloading ARTA yet, but that's in my plans as well. Greywarden told me to download the "big three" of measuring lol. I've been learning how to use PCD lately, bit I've never tried speakerworkshop. Ill have to give it a try.

[blackbox]

Re: Questions From a Speaker Measuring Noob.

I haven't gotten around to downloading ARTA yet, but that's in my plans as well. Greywarden told me to download the "big three" of measuring lol. I've been learning how to use PCD lately, bit I've never tried speakerworkshop. Ill have to give it a try.

Don't bother trying to learn to use Speakerworkshop to measure speakers/drivers...it is a real pain in the arse and ARTA is much better..Just use it to help you design x-overs...that part is really easy when you get the hang of it.

[blackbox]

Re: Questions From a Speaker Measuring Noob.

I haven't gotten around to downloading ARTA yet, but that's in my plans as well. Greywarden told me to download the "big three" of measuring lol. I've been learning how to use PCD lately, bit I've never tried speakerworkshop. Ill have to give it a try.

When you learn to use the “optimizer” in SW you will never want to use anything else. Forget those other x-over design helpers and start out the right way...Speakerworkshop ;)

[rpb]

Re: Questions From a Speaker Measuring Noob.

I could never make Arta work at all, but I use old computers. That could be part of the reason. As for x-overs, I do mine by trial and error. I enjoy playing with PCD on other peoples speaker projects, but I'm shakey on some of the details of getting everything setup before making the filters. Ryanbouma is a good person to ask those type of questions.

[rpb]

Re: Questions From a Speaker Measuring Noob.

Hey guys. I'm putting together all the things I need for a decent measurement set-up, but I have a few questions regarding a few of the components. I would also appreciate any suggestions as to other items that might come in handy.

First off, here is what I have so far:

Dell Inspiron E1505 with Windows Vista Home Premium. An older laptop, but after a recent RAM upgrade, this thing is still going strong!

Laptop's internal sound management is via SigmaTel High Definition Audio. Only output is the normal 3.5mm (1/8") headphone jack.

Dayton EMM-6 Mic (currently uncalibrated, but I found the cal file on PE's site for mine)

Blue Icicle

Dayton 25' Mic Cable (on the way from PE as we speak)

So far I've downloaded both HOLM and REW. Another forum member suggested that REW would be easier to implement for a measuring noob.

The only amp I have at the moment to power the speakers is an old Fisher 5 channel receiver. This is the receiver I have set aside to do some testing. It's a little older (mid 90's model), but it puts out clean sound at 100wpc. Plus it has manually adjustable EQ level knobs across most of the band. Not sure if that would come in handy for measurement though. For now can I just use one of the L or R channels for a signal? I have a nice Belkin 3.5mm to RCA cable for stereo output from my laptop, and the receiver has more than one 2 channel stereo mode. I also have a pretty solid kit for a 68wpc x 2 LM3886TF chip amp, but I haven't had time to build it just yet.

As far as my questions go, these are ones I searched for but couldn't find answers to:

At what point in setting up everything do I use my mic calibration file, how do I calibrate it, and what is used to calibrate it? I know some have the better Cross Spectrum calibrated EMM-6. For now, the current Dayton cal file will suit my needs, but does Cross Spectrum offer services to calibrate a mic if you send it to them?

When measuring I will have 3 different volume levels to consider. My laptops volume, the amps volume, and the gain on my Blue Icicle. What is the norm setting for all these during measurement? I know there are ways to adjust the dB level in the measurement software, but is there a general rule of thumb for the hardware?

Lets say in a two way speaker, I've noticed that some will send a signal to the woofer, then the tweeter and measure them separately. Others will send a signal to the woofer and tweeter at the same time wired in parallel. Is there a general rule of thumb for these different ways of measuring? Or is it just preference of the user coming in to play?

That's all I have for now. Any advice or feedback is appreciated. Hoping to learn more as time goes. I have all kinds of drivers sitting around now, and plenty of XO components. So this winter I plan on having some measuring fun in seeing what all kinds of crazy stuff I can come up with. :D

Thanks!


Ryan

A bit of trial and error is involved to optimize the gain settings. It should work reguardless, but you may get a better signal to noise ratio with some tweaking. That really only comes into play if you are trying to do distortion measurements.