Hell Yeah, Success!

[SteveCallas]

Dyazdani was kind enough to send me a SounBlaster soundcard that he was no longer using. My previous FR measurements of my sub were done with the WinISD tone generator, an integrated sound card that came stock in my Compaq, manually reading what my RS meter said for each tone, then plugging it into Microsoft Excel. Now with this sound card I was able to start using RoomEQ. Slowly followed all the directions and setup tasks, and finally got to do measurements. At first, I thought something had to be wrong, because I was seeing a big dropoff below ~32hz, and experimenting with higher frequencies, they were much louder. Then it hit me, turn on the sub amp you jackass! I was measuring the response of my mains with the crossover in play......guess I was too engrossed and forgot ops: Ok, turned on the Carvin, here are my results!!

Frequency response at my normal seat on the couch:

To be sure that wasn't a fluke, I repeated the measurement three times and got virtually identical results. To be even extra sure, I put the meter on the floor and did the sweep again - this time I had a big dip at ~40hz and response wasn't as smooth, so this reading is legit. Hell yeah!!! :B No BFD for me thanks :lol:

Frequency response on the other end of my couch, roughly 2' away:

Almost identical, but the upper bass is a tiny bit smoother.

Now I wanted to find out what my real tuning was, as I am in the process of building a second sub as was planning on the port being about 4" longer to lower the tune even more.

Close mic FR:

Looks like a lower tuning won't be necessary, I'm already at ~13.5hz! Perfect!

Now I wanted to see what the difference was with the port blocked, to get a sealed FR with a Q of .565. Sealed response at my seat:

Gradual dropoff at around 28hz, as was to be expected. Have a bump in there below 20hz that was probably caused by the port block not sealing the port 100%, so I took a close mic FR of the sub with the port sealed. Sealed FR close mic:

Just as common logic and WinISD predicted!

All this time I knew I couldn't have possibly have had a dropoff below ~25hz, as that wouldn't make any sense and wouldn't reflect what I have been experiencing for the past nine months. The step in which I calibrate the sound card shows that even this Soundblaster started dropping off below 30hz, so I can only imagine what my old cheapo integrated card was doing. This also confirms that the digital RS meter will output the correct data through the RCA jack, while it won't be showing the correct readings on the meter. I also think my high vaulted ceiling helps out greatly in keeping the overall FR so smooth - since my sub is 7' tall, a typical 8' ceiling that is flat would probably be giving me big peaks and nulls.

I'm pretty happy, finally a true sense of what my sub is actually doing, and I prevented myself from accidentally tuning my next sub too low. I will continue to support large, low tuned ported subs, probably now more than ever :T

Will the RoomEQ and RS meter give me somewhat accurate results if I start trying to measure the response of my mains?

[dyazdani]

Then it hit me, turn on the sub amp you jackass!

:rofl: Glad the soundcard worked out OK...

[bobgpsr]

Very very nice results Steve!

Are you ready for some in-room max SPL tests yet? :naughty:

Bob

[SteveCallas]

Are you ready for some in-room max SPL tests yet?

I thought I was going to do some of those back when I did my "threshold of usefulness" testing with very low frequencies this past winter. I quickly realized that an apartment is NOT the place to do max spl testing :B I did a 20hz sine wave that registered at 96db uncorrected using the reading from the meter, and I think I really stepped past my friendly neighbor boundaries. Max testing will resume when I get a house.

[Joe L.]

Steve,

That frequency response looks a "tiny bit" better than most of the subwoofers you will find at "Circuit-City" or "Best-Buy" :B (most of theirs don't do too well when you get down to the single digit frequencies.)

Wait till you get your second sub on-line.

I've been living with 2 18" Avalanche drivers in dual 12.5 cubic foot sealed enclosures in my theater since December and I'm completely spoiled. I can't even bear to listen to most subs I hear in the mass market stores, and walking by the automotive sub department in them is painful. There is no comparrison to what we have with our DIY subs.

Joe L.

[Joe L.]

I thought I was going to do some of those back when I did my "threshold of usefulness" testing with very low frequencies this past winter. I quickly realized that an apartment is NOT the place to do max spl testing :B I did a 20hz sine wave that registered at 96db uncorrected using the reading from the meter, and I think I really stepped past my friendly neighbor boundaries. Max testing will resume when I get a house.

Steve,
Just do your max SPL testing at 10 Hz. Neighbors won't be able to hear it at all and your frequency response is flat enough that the measurement will still be valid. (besides, you can call the local paper and report the seismic event along with them ;x( ;x( )

Joe L.

[SteveCallas]

Absolutely, and a big thanks goes to you Joe for planting the seed of using a large ported sonosub in my head! I only wish that RoomEQ would let me sweep lower than 10hz so I can see where the true rolloff starts when taking room gain into account.

I definitely can't do the max testing at 10hz, as 10hz played beyond a certain threshold causes my kicthen counter to literally start pounding the floor. My ceiling fan rattles pretty crazy too.

[ssabripo]

dayum!!!!!! :E ;x(

not bad for a boilermaker...not bad at all! :T That's pretty awesome and Flat FR if you ask me...Bee Ef Dee, Schmee Ef Dee! Actually, depending how the subsequent subs affect this FR as you bring them online, you may benefit...but looks damn good to me!

[SteveCallas]

Yeah, I'm now a bit reluctant to add a second sub into the mix......I definitely don't need the extra headroom in this apartment.

Oh, and here is one that extends a little higher to see how the sub blends in with the mains and if my upper bass in on par with the lower bass:

Could use a small boost there at ~108hz, but nothing I'll think twice about.

[Dennis H]

Lookin' good Steve! No BFD required. :T

I'd think seriously about forgetting the second sub. It can't improve your response (might make it worse) and you don't need the headroom in an apartment.

[SteveCallas]

I'd think seriously about forgetting the second sub.

In terms of the apartment, yeah, I think you're right. Overall though, I'll still be completing 2-3 more for when I get a house.

[Joe L.]

I definitely can't do the max testing at 10hz, as 10hz played beyond a certain threshold causes my kicthen counter to literally start pounding the floor. My ceiling fan rattles pretty crazy too.

No problem... Just do it a 3AM, when nobody is awake, and then run out into the street in your PJ's (along with the other neighbors) shouting earthquake!!!

Ever wonder what the natural resonance of your building might be? (hint... do not test at high levels at that frequency)

Question... when you socialize and talk about your "huge subwoofer" and how "size does matter," and "I'll bet you've never seen one this big" to prospective mates :blonde:, how do they react? Awe? Shock? Wonder? or perhaps something else? :E

Good thing I'm already married... :T :T :T

Joe L.

[wkhanna]

OK, so size may matter, but flat is where it's at!

Very nice!

[SteveCallas]

Question... when you socialize and talk about your "huge subwoofer" and how "size does matter," and "I'll bet you've never seen one this big" to prospective mates , how do they react? Awe? Shock? Wonder? or perhaps something else?

Lol, I don't brag about my subwoofer size to girls.....that might lead to disappointment later on :B

Ever wonder what the natural resonance of your building might be? (hint... do not test at high levels at that frequency)

I dunno, but when that kitchen counter starts pounding the floor with 10hz sine waves, as if the shockwaves running through the floor are temporarily lifting it and then it is slamming back down, it is very unnerving. Thinking back to when I was at Jon's and he was playing the Master and Commander cannon blasts at loud levels, and you could literally feel the floor flex with each shot - not rattle or vibrate, but flex - it really kinda puts you in awe of how much energy simply moving air rapidly can create.

[roadrash]

Steve, since only one of those water heaters is all you need to
get your bass fix I'd be happy totake one of the other 18's off your hands
PLEASE!!!!!!! ;x(

[steve nn]

No BFD for me thanks

No way man!..don't change a thing Steve. Talk about FR response out of the shoot!.. or maybe I should say tube. Very nice and good for you that you finally confirmed your thoughts. :E :T

[chasw98]

I want one of your now extra 18's.

[bobgpsr]

I want one of your now extra 18's.

And I'll take the other one, plus your stored sonotube. Worth a trip to St. Louie ;lx

Just think of all the extra space that will give you when Chuck and I solve your extra stuff problems. :B

[Dennis H]

You guys are dreaming. To paraphrase Charleton Heston, you can pry Steve's spare 18s out of his cold dead hands.

[HMenke]

Stellar results, Steve! Wow, you truly could not ask for better! 8)

It'd be interesting to see a close-miked curve at the port and see if you get a peak at 13.5 Hz to match your driver dip.

I think RoomEQ Wizard and the RS meter are fine for measuring the mains, but I haven't learned how to apply 1/12th or 1/6th octave smoothing. Without smoothing the FR of the mains looks like the output of a seismograph.

Also, what are the dimensions of your room?

Henry

[---k---]

Ever wonder what the natural resonance of your building might be? (hint... do not test at high levels at that frequency)

Going from memory here, but a good approximation would be:

T=0.3h^.75

h= height of building

[SteveCallas]

You guys are dreaming. To paraphrase Charleton Heston, you can pry Steve's spare 18s out of his cold dead hands.

Yep, that about sums it up The Brotherhood is strong, but uhhh, not that strong.

It'd be interesting to see a close-miked curve at the port and see if you get a peak at 13.5 Hz to match your driver dip.

I took one, and there was indeed a peak right around 13.5hz, but it wasn't significantly higher than the rest of the response, meaning that the meter was still picking up most of the output from the driver, even all the way at the top of the sub. I didn't save it because it really didn't really show me much.

I think RoomEQ Wizard and the RS meter are fine for measuring the mains, but I haven't learned how to apply 1/12th or 1/6th octave smoothing. Without smoothing the FR of the mains looks like the output of a seismograph.

Why is that? Is it something wrong with the program or are you trying to say that a speaker's response in room will be far from flat?

Also, what are the dimensions of your room?

Ehhh, tough to say, it's definitely not a rectangle. The living room and kitchen are combined, the ceilings are vaulted, and there are several non parallel walls. It's a fairly large space, just under 350 square feet, and the ceilings are 12' at the highest point down the middle.

[HMenke]

I think RoomEQ Wizard and the RS meter are fine for measuring the mains, but I haven't learned how to apply 1/12th or 1/6th octave smoothing. Without smoothing the FR of the mains looks like the output of a seismograph.

Why is that? Is it something wrong with the program or are you trying to say that a speaker's response in room will be far from flat?

The actual in-room response is absolutely filled with reflections. To more accurately measure a speaker's true response, you have to place it in the middle of a tall, wide, fairly dead room with the mic fairly close. To see what I'm talking about, just go ahead and sweep your system up to 20kHz and have a look. :E

Ehhh, tough to say, it's definitely not a rectangle. The living room and kitchen are combined, the ceilings are vaulted, and there are several non parallel walls. It's a fairly large space, just under 350 square feet, and the ceilings are 12' at the highest point down the middle.

That sounds like an ideal sub environment. You'll have to keep that in mind when you build/buy a house!

[SteveCallas]

I tried starting a thread a while back that would allow everyone to pool their knowledge so we could try to come up with an ideal, scalable listening/theater room, but it never took off. DIYers go to great lengths to make audio equipment that rivals or bests the top commercial offerings, yet aside from some acoustical treatments, you don't read much on designing and building a great listening room from scratch. I realize most won't have that opportunity, but it would still be nice to solve the problem - oh well. Here it was:

http://www.avsforum.com/avs-vb/showthread.php?t=632169&highlight=scalable+ideal+listeing+room

Next time I drag the computer into my living room, I will try measuring the speakers, as well as doing a lot of other experimenting. If I end up with a receiver that has autoEQ, I'll be very interested to see before and after shots to see what is has really done.

[Paul H]

Thanks for the link Steve - very timely as I'm moving in a month or so and will be building out a home theater. :T

Paul

[Scott Simonian]

So you aren't going to be needing those drivers now are ya?

[Mark Seaton]

Hey Steve,

Welcome to the world of measurements. Bigger, open rooms most certainly afford some wonderful benefits with good placement. For as cheap as a BFD is, I'm surprised you wouldn't be even more interested to have one now so you could make some adjustments to the response curve and do some real experiments as to what you hear. I think you might be surprised. The real issue is that a BFD ain't worth squat without the ability to take measuremnets.

While things do look very good, this measurement/response has me wondering if there is a mix up in some correction factors:

Just as common logic and WinISD predicted!

Does that really look at all like the predictions? There should certainly not be a peaked response in the 20-30Hz range on any simulation I've looked at for a sealed implementation of the Avalanche 18. The only thing that might explain this is a rather low height base-plate resulting in mass loading of the driver from the front confinement. A near field (couple inches from the cone) measurement of the Avalanche 18 should show a notable HF roll off/shelf above 50-60Hz and a fairly constant downward slope below 30Hz in the sealed config. I'm wondering if there are correction factors being used that shouldn't be. Other than that, great work. That sub is obviously a monster. Power to big boxes. 8)

[chasw98]

Hey Mark:
I offered to lend Steve my BFD a couple of months ago. He declined. The offer is still open! Just a way of repaying him for his time and effort in helping me with my sub.

[SteveCallas]

Why put my sub signal through an extra A/D and D/A process if I don't have to? The shorter and simpler the signal path, the better. Jon and I have a blind listening test with a group of people coming up on May 20 with processors, and after that is done, we can also test with my port plug and various high pass filters using an HK 635. If Ryan shows up, I'll be interested to hear his opinion on a sealed RLp15 vs a ported Avalanche 18.

As for the increased low end with the close mic sealed measurement, all I can guess is it occured because the sub was in a corner, and the mic placement was on the base plate roughly 6" from the driver and 24" from the middle of the corner. My base plate is 36" in diameter.

Power to big boxes 8)

Big tubes :T

[---k---]

Steve, are you asking me to put my sub in the trunk of my car and bring it with??? It just might fit you know. :B

[SteveCallas]

No You're subs have been done for a few months now, I'd imagine you have a pretty good idea of what they are capable of. Just want to see if the extra extension will be dramatic enough to be easily noticable.

[JonW]

Steve, are you asking me to put my sub in the trunk of my car and bring it with??? It just might fit you know. :B

Ryan,

Feel free to bring your sub to my place, when we all meet up in a few weeks. But, you know... only if you want to leave whimpering and crying after your sub is humiliated by mine and Steve's. :P


-Jon

[---k---]

Jon, it looks like I won't be able to make it, but I would like to hook up some other time.
As far as my sub being humiliated by yours, I'm picturing a stack of four of mine taking up about the same amount of space as one of yours. Do you think your's could humiliate four of mine.

[JonW]

Oh no- you can't make it? That's too bad. But yes, we should hook up some other time.

We'd have to run the simulations. And I don't have an intuitive feel for these things. But I would think that 4 of your subs could outdo 1 of mine. Mine has but a wee single driver. And you would have more options for placement throughout the room. 4 of them? ;x(

[SteveCallas]

Yeah, he just wimped out today :x If the other professor from Purdue shows up we'll still have four though, and possibly the Sunfire - I'll give them a call and shoot you an email Jon.

I'm picturing a stack of four of mine taking up about the same amount of space as one of yours. Do you think your's could humiliate four of mine

Same space at about 3x the cost, fair is fair. I like to compare on a per driver basis.

[HMenke]

Tastes Great! .... Less Filling! :B

[steve nn]

Since you have a empty seat! I guess I could throw my sub in the trunk and haul it over? :?:

[Exocer]

Wow, I am definitely excited about this gathering...Wish I could be there to experience it!

[SteveCallas]

Since you have a empty seat! I guess I could throw my sub in the trunk and haul it over?

Wow, I am definitely excited about this gathering...Wish I could be there to experience it!

Damn, me and Jon were just discussing inviting one more person, preferably someone from the boards so they can engage in the conversation that is sure to follow no matter what the outcome. Could either of you guys really make the trip to Lafayette, Indiana, on May 20? It will likely be an all day event.

[chasw98]

Steve................
What kind of car do you own that will that dual SS in? Wish I could be there.

[steve nn]

Could either of you guys really make the trip to Lafayette, Indiana, on May 20?

I would love to Steve, but we already have to much on the platter for this year. Tell you what though..I have five weeks a year and would gladly plan one of them around a gathering next year? I would need the date by the end of November or so though for slotting the VK time. I know I would really enjoy it and would cherish the time with my old HT/DIY subwoofer buds. Thank you for the offer. 8)

What kind of car do you own that will that dual SS in?

Uhhhhh... it's a little car with a big trunk! :rollhead:

[chasw98]

I have five weeks a year and would gladly plan one of them around a gathering next year? I would need the date by the end of November or so though for slotting the VK time. I know I would really enjoy it and would cherish the time with my old HT/DIY subwoofer buds. Thank you for the offer. 8)

You know, I get 3 weeks a year. You might want to give enough lead time that some of us on line basshead brothers could possibly get together. I keep reading about this Chicago DIY G2G and have never seen or heard of it anywhere else. Why, with enough notice, Illka might show up!

[steve nn]

Why, with enough notice, Illka might show up!

Now that would be a trip as would meeting the rest of you. Maybe Steve will have his house by next year and we can all come over and trash it. :T

[chasw98]

Hey for housewarming presents we could all bring large heavy duty banana plugs for his 4 tubes!

[SteveCallas]

I would need the date by the end of November or so though for slotting the VK time

You might want to give enough lead time that some of us on line basshead brothers could possibly get together

Interesting. I'm sure we can set a date with a years notice. As for Ilkka, I'm still waiting for him to join the club and build his own subwoofer.