Erin's Audio Corner (my new review YouTube channel/website)

ErinH

ErinH

Audioholic Chief
Mods: I don't *think* this violates any rules but if it does and needs to be removed, please let me know how I can still share this info since I think many here will be interested in it.


Many of you know that I used to do speaker/driver testing for a number of years for DIYMA before moving on to creating my own site (medleysmusings). If you have no idea what that is, it’s a site I used to post objective data to and share with the community. It was focused on providing frequency response (on and off-axis) as well as THD and a few other things along with analysis for various speaker drive units. I took the last couple years off due to personal reasons. But I'm gearing back up to do something big, at least for me. I’ve been itching to change things up and move my review format to YouTube and also expand out of raw driver testing and instead provide a wider range of information. So, that's what I'm doing.


The core of my efforts will focus on product reviews and tutorials (i.e., how to use a DSP, how to tune, what to listen for, etc) along with some other miscellaneous things. I will continue to provide objective data when I can/where it makes sense and I plan to do that as a supplement to the YouTube format; providing the data via a new website. I have a long list of ideas that I’ve collected over years. I think I have a few ideas for my reviews you all will really dig.


I have created a Facebook Group page for those who want to follow it. This page will be a way for me to update everyone on progress I make toward completing reviews. If I get a new piece of hardware to test I’ll share it. Links will be posted to reviews. That sort of stuff. It’ll be an extension of my YouTube review page because, frankly, it’s easier to support conversation here than it is on YouTube. Here’s the link: https://www.facebook.com/groups/607627396679113/


To be entirely transparent, I hope to be ad-driven at some point and also do some affiliate marketing (i.e., Amazon, Parts-Express, etc) so I can use some of the advertising revenue toward purchasing new test equipment and products to test/review. I don’t see me ever actually making money; breaking even would be nice. I’ve already sunk nearly a grand in to what I need to get going. In order to get to the point where I can monetize videos through YouTube, however, I’ll need to hit 1k subscribers, and some crazy number of hours viewed per month. So, I ask you all, if you are interested in any of the stuff I’ve done and the past or you just want to support what I’m doing, go ahead to my YouTube page and click the subscribe button. I don’t have anything out there at this moment in the way of reviews but I’m already working on some really, really cool stuff. And if you are interested in the items I review in the future, feel free to click any links I provide to my affiliate advertisers so I can get a small percentage of the purchase fee (hey, you were gonna buy it anyway). All that helps me keep this thing rolling and keep me from going in debt in the process.


Here’s a link to my YouTube page:




And that’s it… I just ask you to bear with me. I’m not a video editor so I don’t expect to knock this stuff out of the park my first few attempts. But over time, with your feedback, I will hopefully improve the final product and provide an entertaining and educational set of videos. :)


Thanks,


Erin
 
ErinH

ErinH

Audioholic Chief
I've managed to port over a decent bit of my old tests to the new site now.

I also posted this video that hopefully will give you guys an idea of who I am and my passion for doing what I'm doing with the site.
 
ErinH

ErinH

Audioholic Chief
I have also been in talks with Klippel. I am awaiting a quote from them on the measurement gear I'd like to use. Hopefully I can swing it ... that would be pretty epic to be using their stuff again. :)
 
ErinH

ErinH

Audioholic Chief
Well, I got a quote from them this morning. As expected, however, it’s not cheap. Regardless, I’m moving forward and will be sending payment shortly. But I would really appreciate any donations from the community that I can get to help me offset those costs and, namely, to help fund some of the other things I would like to purchase to help me make my testing more efficient and accurate.

If you don’t mind helping out, you can use the link below to contribute to via PayPal (they take 3%, I’m OK with that):

https://www.erinsaudiocorner.com/contribute/

Some of the things I'll be able to provide are:
  • Frequency Response on/off-axis (and from that I can calculate power response, early reflection windows, etc)
  • Harmonic Distortion
  • IMD
  • Max SPL (using the Tone-Burst Module)
  • Thiele-Small Parameters
  • Large signal parameters
  • Linear Xmax using a laser for maximum accuracy
  • Various other items


If you don’t care about the rest of the details then there’s no need to read any further. However, if you’re interested in what your donations would be going toward, keep on reading…

I want to provide as much accurate information as I can about drive units, speakers and whatever miscellaneous ‘tasks’ I take on. IMHO, Klippel products will provide far more depth of knowledge than anything else and that’s why I’ve chosen their product(s). But I also want to keep my hobby/family balance. Testing takes up a good deal of time; but it's not so much the "test" as it is the setup/takedown time: cutting baffles, setting up the measurement rigs, getting the cabling out and running all the wires, fixing the driver/speaker to the test stand, and then writing up the report. In the time it takes to get prepped for a test I can complete another test cycle.

To help with accuracy and efficiency, I also hope to build a dedicated "test" space in my attic. I have about 11x17 feet that I'll need to floor, wall, and insulate to make it a test room. The reasons this is important to me are:
1) Scientifically speaking, the space would be large enough to push the first reflection out another 1 or 2 milliseconds which may not sound like much but is another 200hz or so of accuracy in my measurements. 200hz is a lot when you're expanding that over multiple octaves.
2) It gives me a fully repeatable environment to work within whereas my garage is a state of constant flux with temperature, humidity and ... stuff. Having a dedicated area means that the ambient conditions are within reason throughout the year but also it means that I won't have to spend hours setting up gear and taking it down to complete a couple tests which would help me complete more tests over time.
3) If I were to go this route I could also build an ‘infinite’ baffle to help with drive-unit testing.

Another thing that would help immensely is a small, tabletop, CNC. For raw driver testing I use a large baffle which has a cut-out for inserting smaller baffles. These smaller baffles are the pieces that the raw drivers are attached to. In my previous years of testing I didn't have the ability to surface mount complex drivers or oversized flange drivers. This was a detriment to my results (I always noted when that was the case). Surface mounting is the proper way to test drivers. I do own a router but the time it takes to cut flush-mount surfaces for some drivers … well, it adds up over time. Therefore, I would also like to purchase a small, table-top CNC router so I can cut my baffles to the exact dimensions needed for a driver cut-out. I've got my eye on an item that is just large enough to cut the baffle templates I need.

The third thing is having an automated turntable for polar measurements (on/off-axis frequency response). Now, I can build one from wood … I’ve done it before. But it’s a manual turning system which consists of: measure speaker, go turn speaker, measure speaker, go turn speaker… doing that in 5 to 10 degree increments over 90 to 180 degrees takes time. So, it would be really nice to use one that’s automated and works with the Klippel where I could click the run button and let it measure and rotate automatically. Again, this helps with repeatability and accuracy. But these are not cheap, either. I’ve gotten a couple quotes back > $3k. So, this is probably more of a pipedream at this point.

Obviously I wouldn’t be doing this if I didn’t enjoy it and feel like I’m learning from it as well so I’m not about to cry “woe, is me” here. But presenting data to the masses requires an extra level of accuracy and robustness that throwing together a simple test setup in my spare bedroom and caveating to the nth degree cannot provide; I know this from experience. So anything you can donate to help me with that would really and truly be appreciated.

Thanks again,
- Erin
 
ErinH

ErinH

Audioholic Chief
I won't bump this one again until I get some more updates but for those who would like to help me offset some of my costs on the Klippel and all the other stuff I need to purchase to fund this machine...

One of my car audio buddies also set up this GoFundMe page here which I thought was wicked cool of him to do so if you'd rather support that way than through PayPal here's the link:
https://www.gofundme.com/f/help-hardison-erin-hardison-that-is?utm_source=customer&utm_medium=copy_link-tip&utm_campaign=p_cp+share-sheet


I truly do appreciate any help you're able to provide. I'm doing this stuff whether or not I get the support but if you can help out even a little bit, I really would appreciate it.

Thanks,
Erin
 
ErinH

ErinH

Audioholic Chief
My Klippel order came in last week and I put together an 'unboxing' video to share with everyone. I figure most of us are in isolation these days and could use a 10-15 minute break anyway. :D

 
ErinH

ErinH

Audioholic Chief
Just an update...

I purchased a mic stand over a month ago. After 2 shipping issues, I finally got the 3rd one and it was good to go. I also ordered some speaker stands and planned to use one for speaker testing. But after doing some testing I realized that was a no go. The stand was a bit shaky at above 6 feet. Plus, I wanted something a bit easier for takedown and set up. So I cannibalized my basketball goal (I need a new one anyway). I buried the pole about 2 feet in the ground and rigged up a platform from HDPE and Plywood (to be sealed soon). The platform can also be swapped out to accommodate larger speakers (floorstanders laid on their side to capture vertical response). The pole is very sturdy and can be removed from the ground and placed in my storage area between tests.

The speaker stand is now at 8.5 feet off the ground and 9 feet away from the patio cover. Nearly everything I test will be reflection free to 9 feet. Which puts the first reflection at about 12 ms; or about 80hz. Doubling that means good resolution above 160hz. That’s good. Real good. More than adequate when you consider I will be using a ground-plane measurement for LF response and "stitch" that to the FF measurement closer to the 200-300hz region. As for external noise; I live in the country. So it's mostly quiet aside from some lawnmowers and birds chirping now and again. The software/hardware is smart enough to ignore most noises and multiple sweeps will help keep them from sneaking in to my measurements. IOW, I don't have any concerns here.

I tested hoisting up a 50# bag of sand. That wasn't easy. But was do-able. I'm gonna need a crane, though, if I ever test a floorstander that has significant weight to it. But I'll burn that bridge when I get there. :eek: :D

Here's a few pictures with my 6 foot ladder and myself as a reference.

The last picture is of the mic stand. This sucker is a beast. Can be stood to almost 8 feet tall and the mic can reach higher when the boom is angled.
Here's a link if anyone is wanting to see more info.


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S

shadyJ

Speaker of the House
Very nice! I wish I could get up that high. Will you be installing a turntable to rotate the speakers?
 
KEW

KEW

Audioholic Overlord
You might also consider keeping an eye out for anyone who has access to a CNC. In an earlier job, All you would have to do is send me the data (or a drawing) and I could of run the part after hours on any given day. Unfortunately, that was 20 years ago and I don't have contacts there anymore.
Also, if you have a Woodcraft or similar woodworking store near you, inquire about woodworking clubs (for gentrified woodworkers ;)). These clubs mostly consist of retired folk who like to create/build stuff for a hobby. It is very likely that a couple of these guys would have a 3D ShopBot and are just looking for ways to use it (these are retired guys having fun, not people who would never buy a ShopBot unless it would pay for itself). I realize that Atlanta has a big advantage due to the population, but I think I would have no problem finding a couple of guys around here who would be happy to run a couple for the fun of it given your enthusiasm and would be more than willing to give you access to it on a long-term continuing basis for something like $15/hr.
At least something to consider until you can get the funding to buy your own.
 
KEW

KEW

Audioholic Overlord
Very nice! I wish I could get up that high. Will you be installing a turntable to rotate the speakers?
Good question! He might appreciate knowing how you work yours.
He did have this comment if you missed it! (but that doesn't answer the question of if/what he will do in the meantime).
The third thing is having an automated turntable for polar measurements (on/off-axis frequency response). Now, I can build one from wood … I’ve done it before. But it’s a manual turning system which consists of: measure speaker, go turn speaker, measure speaker, go turn speaker… doing that in 5 to 10 degree increments over 90 to 180 degrees takes time. So, it would be really nice to use one that’s automated and works with the Klippel where I could click the run button and let it measure and rotate automatically. Again, this helps with repeatability and accuracy. But these are not cheap, either. I’ve gotten a couple quotes back > $3k. So, this is probably more of a pipedream at this point.
 
ErinH

ErinH

Audioholic Chief
Very nice! I wish I could get up that high. Will you be installing a turntable to rotate the speakers?
Well, I made a DIY turntable from a lazy susan and a couple scrap pieces of plywood which supports up to 1000 lbs. See GIF below. That's what I had planned to use. Then a friend said "hey, where is your point of reference: the baffle or the center of the speaker?". He said he did the latter. I prefer the former. Meaning: I want to measure with the baffle being the center-point; the radius of my measurement is always relative to the baffle itself. In doing so, that means the baffle has to be at the center of the lazy susan. Which brings up the concern of potential reflection from the lazy susan / platform itself (i.e., if the baffle is at the center of a 16 inch square, there will be 8 inches in front of the baffle that the will impact - to some degree - the measurement data). Now, one way to remedy that is to have different sized lazy susans; where the front portion does not protrude much further than the DUT. But that's kind of a pain. Then there's the aspect of climbing up/down the ladder to rotate the DUT. A major pain. I also reached out to a few companies regarding purchasing an automated turntable (photography purposed ones are great options) and found some options (some are $$$). But still the concern with the physical placement is of concern.

However, the baffle needs to be the point of reference for me. So that brings me to the easy, although a bit more manual solution of what I have done with driver tests: rotate the microphone about the DUT. And this can be done easily with a rope. Tie a loop around the mic stand, tie the other end to a central-fixture on the DUT stand and move the mic stand (that's why I purchased a caster wheel version). Just a glorified string-compass. :D

It's purely up to the tester how they want to define the reference point and if you do the former (the center of the speaker is the POR) then that's fine. I used a piece of the basketaball goal that will be my center point to rotate the mic stand.




IMG_9359.jpg


IMG_9360.jpg
 
ErinH

ErinH

Audioholic Chief
You might also consider keeping an eye out for anyone who has access to a CNC. In an earlier job, All you would have to do is send me the data (or a drawing) and I could of run the part after hours on any given day. Unfortunately, that was 20 years ago and I don't have contacts there anymore.
Also, if you have a Woodcraft or similar woodworking store near you, inquire about woodworking clubs (for gentrified woodworkers ;)). These clubs mostly consist of retired folk who like to create/build stuff for a hobby. It is very likely that a couple of these guys would have a 3D ShopBot and are just looking for ways to use it (these are retired guys having fun, not people who would never buy a ShopBot unless it would pay for itself). I realize that Atlanta has a big advantage due to the population, but I think I would have no problem finding a couple of guys around here who would be happy to run a couple for the fun of it given your enthusiasm and would be more than willing to give you access to it on a long-term continuing basis for something like $15/hr.
At least something to consider until you can get the funding to buy your own.
Hey Kurt. I actually ordered parts for a DIYMPCNC setup. Just haven't had the opportunity to assemble it yet. I do have some friends with CNC machines who have offered to help with some stuff in the meantime, though. :)
 
S

shadyJ

Speaker of the House
Well, I made a DIY turntable from a lazy susan and a couple scrap pieces of plywood which supports up to 1000 lbs. See GIF below. That's what I had planned to use. Then a friend said "hey, where is your point of reference: the baffle or the center of the speaker?". He said he did the latter. I prefer the former. Meaning: I want to measure with the baffle being the center-point; the radius of my measurement is always relative to the baffle itself. In doing so, that means the baffle has to be at the center of the lazy susan. Which brings up the concern of potential reflection from the lazy susan / platform itself (i.e., if the baffle is at the center of a 16 inch square, there will be 8 inches in front of the baffle that the will impact - to some degree - the measurement data). Now, one way to remedy that is to have different sized lazy susans; where the front portion does not protrude much further than the DUT. But that's kind of a pain. Then there's the aspect of climbing up/down the ladder to rotate the DUT. A major pain. I also reached out to a few companies regarding purchasing an automated turntable (photography purposed ones are great options) and found some options (some are $$$). But still the concern with the physical placement is of concern.

However, the baffle needs to be the point of reference for me. So that brings me to the easy, although a bit more manual solution of what I have done with driver tests: rotate the microphone about the DUT. And this can be done easily with a rope. Tie a loop around the mic stand, tie the other end to a central-fixture on the DUT stand and move the mic stand (that's why I purchased a caster wheel version). Just a glorified string-compass. :D

It's purely up to the tester how they want to define the reference point and if you do the former (the center of the speaker is the POR) then that's fine. I used a piece of the basketaball goal that will be my center point to rotate the mic stand.




View attachment 35516

View attachment 35517
If there was some way to affix the mic's boom pole to the speaker stand so that it could swivel around, that would make testing a lot easier for you. If you are actually repositioning the mic stand for every off-axis angle, I can't see how that wouldn't become very tedious and time-consuming. I would try to find a way of spinning the speaker itself, that should make life a lot easier for you in the long run.

And yes, its best to spin the speaker around some point close to the front baffle rather than the middle of the speaker. That is the reference axis. The intended reference axes can change from speaker to speaker, as I am sure you are aware, and the real point of spin that you want to get is the depth of the tweeter from the front baffle.

You are correct for wanting the platform for the speaker not to extend beyond the speaker itself. That is going to be challenging to do if the platform is attached to the turntable. If you look at the testing pics from some of my bookshelf speaker reviews, you might be able to see how I solved this problem- by separating the speaker platform from the turntable platform. Like this image, for example. While my rig works fine, I am no mechanical engineer, and I am sure there are more efficient solutions for these problems than what I could think of.
 
ErinH

ErinH

Audioholic Chief
If there was some way to affix the mic's boom pole to the speaker stand so that it could swivel around, that would make testing a lot easier for you. If you are actually repositioning the mic stand for every off-axis angle, I can't see how that wouldn't become very tedious and time-consuming. I would try to find a way of spinning the speaker itself, that should make life a lot easier for you in the long run.

The microphone does rotate about the speaker. Picture a string compass. The pole is the center point (the baffle of the speaker, really). The mic is the pencil. The string is what keeps the radius. That's what I'm doing. Except using a rope and a microphone pole. Notice that the microphone stand has caster wheels. That's why. That's the same method I've been using since 2011 when I started testing drive units. It's not a problem when all I cared about was 0/15/30/60 but measuring every 10 degrees is going to get old but that's just what it's going to be for the time being. I wish it were automated. But that's just too much money.


You are correct for wanting the platform for the speaker not to extend beyond the speaker itself. That is going to be challenging to do if the platform is attached to the turntable. If you look at the testing pics from some of my bookshelf speaker reviews, you might be able to see how I solved this problem- by separating the speaker platform from the turntable platform. Like this image, for example. While my rig works fine, I am no mechanical engineer, and I am sure there are more efficient solutions for these problems than what I could think of.
That's a good DIY solution. Not too different than what I considered but I just didn't want to have to create a different platform for various size speakers. As you know, no matter what method you go with there's an aspect of it that isn't perfect. There's a concern with height vs stability, manual time to spin the turntable or the microphone stand, or turntable/stand reflection. The fully automated solutions are way too $$$ for me.


Once this whole COVID-19 stuff goes away I can make a trip to the hardware store to get what I need to build a better version of what I have but I needed something to get me going.
 
slipperybidness

slipperybidness

Audioholic Spartan
The neighbors probably think that you have officially flipped your lid! LOL!

Mission Accomplished. :cool:
 
ErinH

ErinH

Audioholic Chief
So, I finally got set up today to at least start taking some test measurements. I started with the ELAC DBR62 since it's what I sent to Amir over at ASR which he tested and posted a couple weeks ago. My results are ... different. Particularly in how Amir's measurements show a lift from about 600 - 1khz while mine shows the lift from about 1-2khz. Now, this was measured with the DUT about 8.5 feet off the ground and the first reflection didn't occur until about 13 ms (see attached). That means the first reflection does not occur until roughly 80hz (that's a good thing; a real good thing). Now, I played around with seeing what happens if I drop that window down to the standard 3ms that so many are forced to use. The trend still stays the same. You'll also notice I have a smoother response up high; no dip in the 16khz region as measured by Amir. I did play with adding foam to my mic stand. No real difference was made.

Point being, outside measurements has kind of been considered the next-best-thing to anechoic (and now NFS) measurements but there's a decent difference in what I measured (with a huge window of time being reflection free). I'm going to do this again tomorrow and if I find the same results I'm planning on contacting Klippel to see what they think.


I don't necessarily think there is anything alarming here; not yet, at least. But I wanted to share.

Note: Measurements were conducted with no ambient noise (no cars, no kids screaming, etc.) Measurements were averaged with 2-4 sweeps to help remedy any external noise, just in case, as advised by Klippel R&D. ;)

IMG_9373.jpg



untitled.png


test1.png
 
ErinH

ErinH

Audioholic Chief
After having shared the above post and spending the day conducting said tests, I am seriously considering overhauling my method for off-axis measurements. Right now I am spinning the mic about the baffle of the DUT as I described earlier. Easy enough. But doing it 10x today for the 0 - 90 degree measurements got old. Fast. I built a turntable a couple weeks ago but decided against it. Now I'm going to play with that idea more tomorrow again. I really wish I could afford some way to automate this stuff with one of the various heavy duty turntables out there but those are a cool $1k even for the most modest options. So for now I'll just deal with the manual method.

I also now need an 8 foot ladder because that 6 foot ladder ain't gonna cut it when trying to lug a speaker up and down it and hoisting even the little bookshelves over my head to reach the 8.5 foot pedestal height. So I'll be shopping those tomorrow; hopefully someone has some on sale. :D
 
S

shadyJ

Speaker of the House
After having shared the above post and spending the day conducting said tests, I am seriously considering overhauling my method for off-axis measurements. Right now I am spinning the mic about the baffle of the DUT as I described earlier. Easy enough. But doing it 10x today for the 0 - 90 degree measurements got old. Fast. I built a turntable a couple weeks ago but decided against it. Now I'm going to play with that idea more tomorrow again. I really wish I could afford some way to automate this stuff with one of the various heavy duty turntables out there but those are a cool $1k even for the most modest options. So for now I'll just deal with the manual method.

I also now need an 8 foot ladder because that 6 foot ladder ain't gonna cut it when trying to lug a speaker up and down it and hoisting even the little bookshelves over my head to reach the 8.5 foot pedestal height. So I'll be shopping those tomorrow; hopefully someone has some on sale. :D
I had a feeling that rotating the mic stand would not be viable. As for the difference in measurements between you and Audio Science Review, one thing you should try is measuring at different distances to see if there is any change. I can see you measured at 1m, but try 0.5m and 2m to look for any changes. There probably won't be much of a change, but it's worth trying. What is the microphone that you are using? Are you certain that it has a flat response? One thing I can see is that the ripples above 5 kHz is probably due to the thing that holds the microphone. To get rid of that, you need to mount the microphone at the end of a boom pole, a pole that gives no opportunities for reflections. I got the same type of reflection ripples that you did until I put the mic in the boom pole that you see in my review pics. It's just an aluminum tube with an XLR cable threaded through and a soft fitting piece at the end for a snug fit on the mic.

I can't really explain the other differences. So that speaker is the same exact unit you sent to Amir? Are you sure you measured with the mic aimed at the tweeter exactly? I could see this difference coming from say a 10 degree difference in vertical angle. Also, is there any platform surface in front of the speaker? Because the major differences between yours and Amir's measurements seem to hang around 1 kHz to 2 kHz, and the wavelength of those frequencies is between 6 to 13 inches, so maybe its has something to do with a reflection from the platform. I am just spit-balling here.
 
ErinH

ErinH

Audioholic Chief
To be clear: Today's test for me was entirely a trial run of sorts. I needed to see how easy it was to move things around, get set up, move the mic a bunch of times to get lined up, etc, etc, etc. This isn't anything I had planned to write a report or do a review on just yet. Nonetheless, I have been running my mouth for a couple months now about providing data with my own setup and some of you guys were kind enough to donate so I wanted to at least show you all I am working on getting set up and figured this data would be a fun way to bounce some data along.

The boom pole is the same method I use for driver testing. I didn't do that today because my main concern was seeing how viable the mic stand rotation would be (as you said, it wasn't... as I would say, I hate myself for thinking otherwise). I did put a 2 inch thick piece of foam around the pole at the end because I was curious if that would change the result above 10khz (Amir has a significant dip @ 16kHz). It changed a little but not enough to write about. Certainly not to the degree where it would account for a deep null like Amir's data shows.

The speaker was flush on the platform so now interference from that.

The mic is the Earthworks M23 and the calibration file (as well as sensitivity calibration) was used.
 

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