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Discussion Starter · #102 ·
Well, I've got some IB progress to report. I got my manifold put together and a temporary trapped door for the location I'd like to install the outie IB. I'm going to try installing it on top of a trapped door leading to stairs to get into the basement. The manifold is 3/4" MDF on the outside with the inside lined with 5/8" OSB. It's 24" x 24" x 20" tall and weighs ton with the drivers installed (about 150lbs). I need to get some sleep but here's some pictures, the FR sweep is at the LP with one EQ filter to tame a nasty peak around 45hz:









I rewatched The Dark Knight tonight and was inspired by a thread here to see what I could get during the hospital scene. I quit turning up the volume when I saw the clip lights on the EP2500 flicker, max SPL: 119dB. Sweet
 

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Discussion Starter · #103 ·
Well I've been living with the IB for a couple days now... I'm sold
It just seems to have infinite dynamic capability, no matter how loud I play it it sounds rich and clean. As you've seen from my wall of subs I'm accustomed to plenty of headroom but I never realized before how much the dynamics were being squashed with my old subs, not any more! Playing some of my favorite music tracks is a real eye opener. The SPL level isn't louder but you can really hear/feel the difference in the dynamics.


I spent a couple hours last night tweaking placement and dialing everything in. I decided to run a max output test from 5hz up. I'm sure I have more headroom above 20hz but from 7hz up I'm flat at 110dB! (I know I posted some rather impressive graphs of my 4 eD's but I've since learned those were erroneous, I didn't know what I was doing with REW and had changed the range on the SPL meter after calibrating the SPL which screws everything up...). I don't know how I managed to do it but I lost that measurement, I guess I've been missing too much sleep... I'll have to run it again when I get a chance.


I also played around with THD measurments. Back in March I did some with the eD's and was less than pleased with the results. The IB doesn't disappoint on THD measurments... I started with 10hz and checked in 10hz measurments. Running at 105dB nearly everything I checked was less than 5% THD (70hz was higher THD with less SPL as I have a null there). Below is a snapshot of the 10hz measurment, 105dB fundamental with 3.5% THD


 

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That's cool you're up and running now. I wish there was a member that has an ib closer to tn. I would love to have a listen.
 

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Discussion Starter · #105 ·

Quote:
Originally Posted by brandonnash /forum/post/16931065


That's cool you're up and running now. I wish there was a member that has an ib closer to tn. I would love to have a listen.

Yeah, I felt the same way up here in the middle of nowhere... If anyone happens to be in the area and would like to take a listen let me know (like that'll ever happen
)!
 

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Discussion Starter · #106 ·
I got a chance to do some more "max level" sweeps tonight. I actually quit before the EP2500 started clipping this time (not sure what was different...?). I had my RS SPL meter (digital) set to the 100dB range and REW was telling me I was out of headroom... The first image is the sweeps I ran as I upped the volume (no compression there
), the second is a very nice waterfall of the 117dB sweep:






I'm still REALLY enjoying this thing!!! One of these days I'll have to get the finishing touches done...


I also ordered one of the August HTS member special calibrated ECM8000's. We'll have to see how the measurements compare between the digital RS meter with generic .cal file and the ECM8000 with the mic-specific cal.
 

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Nice thread. Love the pics and details. The youngster is a doll



I just wanted to post your compression graph for you because you mentioned that there's no compression shown.


I also wanted to comment on your mentioning clipping during these sine sweeps. The amp is much more likely to clip with a high dynamic transient than with the steady state sine sweeps.


The black trace is where the gold trace would be if there was no compression. As you can see, there is considerable compression. Since the compression mostly occurs down deep, which isn't typical of a sealed alignment, my guess is that the drivers are running out of throw. It could also be the amp if you have low end boost engaged.


Either way, I wanted to give you a heads up because those high level sine sweeps are brutal and can short a coil or shred a spider without much notice.


The system will perform much better than the sweep indicates during program source anyway, leaving the sine sweeps as not much of an indicator of anything more than when your system will compress when playing high level sine sweeps.





Bosso
 

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Discussion Starter · #108 ·

Quote:
Originally Posted by bossobass /forum/post/16991359


Nice thread. Love the pics and details. The youngster is a doll



I just wanted to post your compression graph for you because you mentioned that there's no compression shown.


I also wanted to comment on your mentioning clipping during these sine sweeps. The amp is much more likely to clip with a high dynamic transient than with the steady state sine sweeps.


The black trace is where the gold trace would be if there was no compression. As you can see, there is considerable compression. Since the compression mostly occurs down deep, which isn't typical of a sealed alignment, my guess is that the drivers are running out of throw. It could also be the amp if you have low end boost engaged.


Either way, I wanted to give you a heads up because those high level sine sweeps are brutal and can short a coil or shred a spider without much notice.


The system will perform much better than the sweep indicates during program source anyway, leaving the sine sweeps as not much of an indicator of anything more than when your system will compress when playing high level sine sweeps.



Bosso

Thanks for the insight Bosso. I guess I didn't even realize the compression was there... When I envision compression I think of the FR graphs from Ilkka's subwoofer tests where it's painfully obvious, especially when the commercial ones are EQ'd. I didn't see anything like that so I was thinking there wasn't any compression
Now that you pointed it out I may have to complete the cutout under the manifold and re-run some sweeps making sure to normalize my steps. I haven't fully cut out the area under the manifold as I wanted to try different alignments before completing the cutout (see pic above). Not sure if that will change things but it certainly could be causing some compression, especially in the VLF range.


As far as the clipping, I think it had more to do with the 5dB of boost I have just under 60hz (at the seat where these were taken that area is a true null but the boost helped a bit at the other two primary seating positions). That said I'm not too terribly concerned about it, I think I've got enough headroom... for now



Also thanks for the kind words about my daughter. I know she's a doll now but I'm scared what will happen in the teenage years... Especially with her younger sister only 14 months behind - just born last Thursday.

 

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Bosso likes to point out the danger of these type of tests plus the fact that it doesn't represent realcontent that'll be encountered and he's right. It is useful to know where you system limitations are though. Looks like you are good on extension to 7hz. I doubt you are going to listen to stuff that loud very often. Knock the ULF's back to the 105-110db level and you are sittin pretty. Can't help you with the 2 daughters...You're on your own there.
 

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Quote:
Originally Posted by lennon_68 /forum/post/16972863



I got a chance to do some more "max level" sweeps tonight. I actually quit before the EP2500 started clipping this time (not sure what was different...?). I had my RS SPL meter (digital) set to the 100dB range and REW was telling me I was out of headroom... The first image is the sweeps I ran as I upped the volume (no compression there
), the second is a very nice waterfall of the 117dB sweep:


My experience with the RS SPL meter requires that your meter's scale must be set to the range being measured. Using the 100 dB range with a 117 dB sweep most likely means the SPL meter's electronics were clipping. The sweeps above 110 dB may be misleading!



Quote:
Originally Posted by lennon_68 /forum/post/16972863



I also ordered one of the August HTS member special calibrated ECM8000's. We'll have to see how the measurements compare between the digital RS meter with generic .cal file and the ECM8000 with the mic-specific cal.



I would love to see the results of that also.
 

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Discussion Starter · #111 ·

Quote:
Originally Posted by Ricci /forum/post/16994393


Bosso likes to point out the danger of these type of tests plus the fact that it doesn't represent realcontent that'll be encountered and he's right. It is useful to know where you system limitations are though. Looks like you are good on extension to 7hz. I doubt you are going to listen to stuff that loud very often. Knock the ULF's back to the 105-110db level and you are sittin pretty.

Yeah, I know Bosso's not down for the subwoofer S&M like you are (I did slap the IB around and call it names during the higher level sweeps, per your instructions). I agree though that it's good to know your system's limits, and it's fun too.


Quote:
Originally Posted by Ricci /forum/post/16994393


Can't help you with the 2 daughters...You're on your own there.

Yeah... actually these two make 3 daughters (4 kids total) we have 6 year old twins too

Quote:
Originally Posted by J_Palmer_Cass /forum/post/16996608


My experience with the RS SPL meter requires that your meter's scale must be set to the range being measured. Using the 100 dB range with a 117 dB sweep most likely means the SPL meter's electronics were clipping. The sweeps above 110 dB may be misleading!

Yeah, I wasn't really sure about that either but recalibrating the SPL level using the 110dB setting (or 120dB setting) didn't sound like much fun... maybe I'll do a trial to see what happens comparing the same level but changing and recalibrating the SPL level again (although there's a bit of error setting the SPL anyways, it'd be interesting to see if there's a big difference).


Quote:
Originally Posted by J_Palmer_Cass /forum/post/16996608


I would love to see the results of that also.

I got the ECM8000 today (haven't even opened it yet, just got home) but don't have a mic preamp to test it out
I had thought I could use the DEQ2496 for that but someone in the other thread just informed me that it doesn't work for that
 

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Discussion Starter · #112 ·
Well, I finally broke down and bought an M-Audio Mobile Pre off flea-Bay. Got it today and redid the max output measurements. The below are in steps of +2dB between traces. At 20hz there is ~2dB of compression between the lowest level and highest level traces (104dB for lowest level, 114dB for highest level which was +12dB from lowest level). Not too shabby at all:




It looks like most of the compression in the earlier graphs was due to the RS SPL meter's range not being set correctly for the measurements...


My next step is going to be to put the DEQ2496 into the system in place of the DSP1124. I'm thinking about trying out the Dynamic EQ but I think that will take some tinkering to get right. My plan was to use the Dynamic EQ to compress the content below 20hz once the level gets over 105dB but looking at the latest traces I'm not sure that it's necessary.


I also have the wood and paint ready to finish the manifold off and replace the temporary trapped door with a permanent one with the complete cutout. I'll be taking a bit more effort to get everything sealed up as well. I'm curious to see how having the full cutout and sealing things up better affects things. The seal is pretty good but there's a board under the trapped door on the recessed floor side that's just loose in there. During loud playback it will vibrate loose. That happened during the sweeps above and the FR got all goofy. I thought I broke something and was inspecting the drivers when I noticed it had blown out, putting it back in place "fixed" the FR.
 

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Quote:
Yeah... actually these two make 3 daughters (4 kids total) we have 6 year old twins too

wow! Congrats on the new addition!!!


Less time for audio
 

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Quote:
I also ordered one of the August HTS member special calibrated ECM8000's. We'll have to see how the measurements compare between the digital RS meter with generic .cal file and the ECM8000 with the mic-specific cal.

You know I have both the Calibrated ECM8000 and the RS digital meter. I never did check the differences.
 

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Discussion Starter · #115 ·

Quote:
Originally Posted by penngray /forum/post/17054873


You know I have both the Calibrated ECM8000 and the RS digital meter. I never did check the differences.

You know I was just thinking about doing it but got lazy... I even had both sitting where I was measuring (to calibrate the SPL). It seems simple enough but then I was thinking how I'd need to switch the sound card setting (input) and load the other .cal file. It seemed like SOOO much work (all of 30 seconds of effort)



I'll have to give this a try some time and see how they compare.


Quote:
Originally Posted by penngray /forum/post/17054868


wow! Congrats on the new addition!!!


Less time for audio

Thanks! Well, actually less time for other hobbies. For now Audio isn't taking a hit, in fact I've taken the 4 weeks paid off from work and have been getting tons of time for audio. Probably too much even... I don't think my wallet can take much more!
 

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Discussion Starter · #117 ·
Well I finally got my IB manifold painted and back in the house. It didn't go so well... Being the cheapskate that I am after I primered and painted it I tried to use some leftover Minwax Polyshades that I had laying around rather than buying a can of Poly. That didn't turn out so good... Dark brown streaks, big runs, and LOTS of bubbles. I had to sand it all off and start over but it turned out alright eventually. It's been out in the garage for the last 3 weeks being painted and waiting for the next coat.


It was all worth it though. It looks great now. I used Rustoleum textured black with Polycrylic on top. One side had some oddities but that's fine, I just put that side toward the wall.

 
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