Usefulness of In-Room LF Measurements vs. No Measurements (ref FH)

[Ray21]

Originally Posted by xrk971

We are all big boys and understand the applicability of a measurement to a particular room. That should not stop us from sharing what our measurement looks like in *our* room....

More data is always better than no data.

I think you're absolutely right and I certainly agree with you.

I didn't intend to completely dismiss the usefulness of sharing measurements, just as long as the knowledge of room effects are known to those interpreting the information the data is certainly very useful. But this is DIY, so it should be a "no duh..."

[Bob Brines]

OK. I'll play. The room is 25'x13'x8'. One long wall, with the speakers centered, and the floor are cast concrete. The left short wall, the back wall and the ceiling are drywall. The right short wall is glass with a heavy cotton curtain over the windows. The left rear corner is open into a 6'x10' landing for a stair will. The floor is covered with carpeting and there is a fair amount of soft furniture scattered about. The speakers are 3' from the wall, 7.5' apart and the chair 7.5' from the speakers. The bass speakers are Dayton RSS315HF-4's in 2ft^3 sealed boxes that are 24" tall. the treble speakers are Alpair 7.3's in folded TL's sitting on top of the bass speakers. The microphone is centered on my head and 2" above my head.

Have fun.

Bob

[freddi]

that's real pretty Bob

[IRONHAND54]

It always amazes me that someone has to have a graph or a chart to take a man at his word about a given subject. Now if one of the speaker designers on this site, with as many years in sum, tells me his/her design will give me x-number Hz-KHz give or take a little either way given room acoustics, then I'm inclined to take them at their word. I'll let my ears be the judge or ask about a way to tune it to my my way of listening. All of the long term speaker designers on here have given selflessly to all who ask!! If you want to have measurements, then build the speaker, get out the mic and the appropriate sound measurement program, and measure until your heart is content. Me, I'm inclined to be thankful of those years of wisdom and dedication, and if they tell me that if you measured the same speaker in ten thousand different rooms that no two results would be the same, then again I believe they might be on to something!!

Just my two cents worth, and we all know the story about opinions!!!

Thanks, Mac

[xrk971]

Originally Posted by IRONHAND54

It always amazes me that someone has to have a graph or a chart to take a man at his word about a given subject. Now if one of the speaker designers on this site, with as many years in sum, tells me his/her design will give me x-number Hz-KHz give or take a little either way given room acoustics, then I'm inclined to take them at their word. I'll let my ears be the judge or ask about a way to tune it to my my way of listening. All of the long term speaker designers on here have given selflessly to all who ask!! If you want to have measurements, then build the speaker, get out the mic and the appropriate sound measurement program, and measure until your heart is content. Me, I'm inclined to be thankful of those years of wisdom and dedication, and if they tell me that if you measured the same speaker in ten thousand different rooms that no two results would be the same, then again I believe they might be on to something!!

Just my two cents worth, and we all know the story about opinions!!!

Thanks, Mac

It's not an issue of trust or whether or not I believe someone's sim. I design and model speakers too (check out all my builds in the FC thread and other threads), and I also make measurements and even provide sound clips if anyone is interested. Measurements don't always agree with sims, and some speakers cannot be sim'd properly unless you go with a 3d finite element approach. Again, it's not just the room effects (below 200Hz), we are interested in intrinsic speaker response above that which is independent of the room.

[freddi]

hope you're not referring to me on the "man at his word" thing (?) - just complimenting Bob on a pretty set of data (had a cat feeding break) - which man? which speakers? which claims? - it does not hurt to have data although I've published some pretty embarrassing stuff ;^)

[xrk971]

Originally Posted by Bob Brines

OK. I'll play. The room is 25'x13'x8'. One long wall, with the speakers centered, and the floor are cast concrete. The left short wall, the back wall and the ceiling are drywall. The right short wall is glass with a heavy cotton curtain over the windows. The left rear corner is open into a 6'x10' landing for a stair will. The floor is covered with carpeting and there is a fair amount of soft furniture scattered about. The speakers are 3' from the wall, 7.5' apart and the chair 7.5' from the speakers. The bass speakers are Dayton RSS315HF-4's in 2ft^3 sealed boxes that are 24" tall. the treble speakers are Alpair 7.3's in folded TL's sitting on top of the bass speakers. The microphone is centered on my head and 2" above my head.

Have fun.

Bob

Thanks for playing along. You have nice measurements frequency wise and HD wise. But the one thing you have is a lot of acoustic 'after taste' due to the impulse response ringing - corresponding to the two cone breakup peaks above 10kHz that the A7.3 is known for. I think percussive sounds will have a shimmer and voices will have a sibillant quality. As I recall, this driver behaves better 15 deg off axis where these peaks go down. However, this acoustic aftertaste may actually be pleasing sounding to some - I believe this acoustic aftertaste makes soft impulses more audible. What this means is that it gives an apparent enhanced audibility of soft sharp sounds that otherwise is not there in the original recording. Some folks may call this "enhanced detail", or it might be the same as DDR to some? This seems to be more common in aluminum diaphragms.

If we look at the comparison between the A7.3 and the TC9FD's impulse response as previously seen here:
http://www.diyaudio.com/forums/full-...ml#post4184730

Here is the A7.3 IR from pnix's measurements, it looks very similar to your IR:


Here is the IR from your measurement:


Here is the TC9FD's IR:


Now listen to what an impulse response sounds like from each driver, which one persists longer and is more audible?

A7.3 IR wav file:
http://www.diyaudio.com/forums/attac...-15-30-deg.zip

TC9FD IR wav file:
http://www.diyaudio.com/forums/attac...-15-30-deg.zip

[IRONHAND54]

My remarks were concerning this entire thread, and not one individual, or one post. I have read virtually every forum in this site, as I'm a disabled military retiree and veteran, with an over abundance of time on my hands. I have seen virtually every design, by a countless number of contributors, courtesy of their time and hard earned money, who have given those with less means a way to have an audio system to write home about. That was where my heart was when I posted. So, now maybe you can see where I was coming from.

Thanks for all you guys do to make this forum something special!!

Mac

[freddi]

hey Mac - I owe you an apology for my snippy tone - Best, Freddy

[xrk971]

Originally Posted by IRONHAND54

My remarks were concerning this entire thread, and not one individual, or one post. I have read virtually every forum in this site, as I'm a disabled military retiree and veteran, with an over abundance of time on my hands. I have seen virtually every design, by a countless number of contributors, courtesy of their time and hard earned money, who have given those with less means a way to have an audio system to write home about. That was where my heart was when I posted. So, now maybe you can see where I was coming from.

Thanks for all you guys do to make this forum something special!!

Mac

Ironhands,

We here in the US all owe you our most sincere respect and gratitude for the service you have given to the nation. Glad you can join us in this forum and in this hobby - welcome aboard! If you have lots of time, get some FC boards, a hot melt glue gun and xacto, a mic and REW software and you are set to go.

Regards,
X