My First Sub

[ThomasW]

As I read Ryan's post, that's at only 2 INCHES from the dustcap. That's not quiet, but it's hardly insane.

That's the uncorrected reading from a RS meter. I imagine it's a bit louder than that.

[Mark Seaton]

Ryan,

You might try wiring both subs in series with eachother and drive it with one of the channels. With the amp set to the same gain, you should be able to compare at what point the amp clips in each case, and you can be pretty confident that in the second case has nothing to do with the driver.

While I know many have had great luck with inexpensive pro amps, my experience is that they work very well... so long as you stay well clear of their operating limits, and have a LOT more power than is "needed." I have been disappointed a few times now in using the cheap Crown and QSC models. The seem to clip much sooner than their bigger siblings, especially when driving lower impedances and lower frequencies.

Dave from the chicagoavforum will be bringing his LAB Gruppen fP-6400 amp with on Saturday. While it's quite expensive, it does dish out >2200W/ch into 4 Ohms and can quickly determine if an amp is the limiting factor. 8)

Of course in any system, something has to set the limit. If you keep adding amp power, at some point you will reach the excursion or thermal limits of the drivers. At least in this case you are unlikely to damage the drivers.

[---k---]

I'm turning it down.

Something is still bothering me. It just doesn't feel right. I just ran trough Avia to calibrate the sub. Playing Avia's tones with the receiver at 0 showed that all my speakers were at 85db. So, Avia's tones are 85db while the internal receiver tones are 75db. Oddly though, using Avia to set the sub, it wants the amp all the way up and the receiver level at -4 to get the pink noise the same between the speaker and the sub. LOUD! (Avia is corrected for the RS meter, right? If not, I guess that would be ~3db hot.) Playing Bella Fleck, it sounds hot. The sub level at -8 sounds about right.

I tried one more thing with the that scene in Incredibles. I put the sub amp all the way up. The sub channel was at -10. At a master volume of -12 I got the crackle. So, I turned the sub amp down a little. Same thing, -12. Turned it to about 75% and at -12 it just went away.

Steve, my chair is 9.5 feet from the face of the sub.

[---k---]

I think one of the hardest things to come to grips with, is the sound. With this sub, I just get slam. My old sub boomed. I don't think I realize how loud the sub is, because it sounds so differnt.

That and it is hard for me to beleive that I need to turn it up so far to get Avia to say it is level, when every monkey with an SVS seems to be able to turn their gain noob up only 1/3 of the way.

Those to things just make me think that there is something I'm doing wrong.

Maybe I should corner load this thing and see what happens.

[---k---]

BTW, speaking of amps. I just got a Musicians Friend catalog in the mail today. Did anyone see what they are selling the Crown XLS amps for! the XLS402 is $249 and the XLS602 is $349.

[Mark Seaton]

That and it is hard for me to beleive that I need to turn it up so far to get Avia to say it is level, when every monkey with an SVS seems to be able to turn their gain noob up only 1/3 of the way.

Those to things just make me think that there is something I'm doing wrong.

Don't get caught up worrying about the gain settings. Most of the plate amps in subwoofers have rediculous amounts of gain available, leaving the setting quite low on the dial. It has zero meaning or significance to how the sub performs. It's a shame that there is a perception that this has some relation to how powerful the sub is. The plate amps effectively have a pre-amp in front of the amp, where "zero" or input = output (to amp section) is rather low on the dial. In the case of connecting to pro amps, 100% or "0dB" is this same relative point.

The dial setting might allow you to adjust an amp to reach max power at 0.2V p-p or at 2V p-p. In both cases, the amp will deliver the same max power. This is just a gain/sensitivity setting.

[SteveCallas]

9.5 feet isn't too far away, I'm at ~9 feet. Dropping from 120db to 96db still seems pretty big to me. Maybe because your doors are open and you have bass traps? I dunno. But like I said, I can see why you would still be wanting more at 96db with just the sub plugged in - I've measured ~100db peaks at my seat during the ice scene from Titan AE with just the sub plugged in and didn't go higher because I have to worry about neighbors - if I had my own house, I'd go a fair amount louder. Do you get pressure waves or pulses in the air or your body from your subs? Perhaps a lot of the bass energy is being disappated somehow?

[steve nn]

and a bottoming spider has more of a beating sound (I'm not familiar with how the RL-p15 bottoms).

When I bottomed mine that's what I perceived the sound to be. Not a clack like what I've experienced in the past, but more of a thump. Maybe it has something to do with the enclosure being sealed as apposed to vented? With no eq it took a good deal of volume with the single unit calibrated flat (83dB) with the RS dgtl meter..

That and it is hard for me to beleive that I need to turn it up so far to get Avia to say it is level, when every monkey with an SVS seems to be able to turn their gain noob up only 1/3 of the way.

Monkey! lol...If you were to hookup a couple of their passive units like the CS+, you would also find the gain on the pro would need to be set higher. Marks explanation summed it up well.

Maybe I should corner load this thing and see what happens.

I think that's a very good idea, nothing wrong with testing it out anyway. If required?...put a 2 X 2 sheet of MDF up against the side of the couch to reflect, I don't think you'll need it though.

[cjd]

You know, I almost wonder if you are simply exceeding the ability of the power supply in that amp to deliver current. I get a nifty crackle-ish noise when the caps drain trying to use a chip-amp designed for an 8ohm load on the big 3-ways + heavy bass + 2.8ohm minimum.

It may be able to deliver the watts steady state but not put out when it comes to a high demand hit.

C

[---k---]

Chris, maybe?

Well, I'll get my expectations in line this weekend when I hook up with Mark. Maybe I'm just crazy.

Does anyone have any thoughts and why I didn't see any differance when I put the amp im bridge mode? It behaved exactly the same, so I think I did something wrong, but not quite sure how that is possible. It is pretty hard to screw up moving the switch all the way to the top.

[chasw98]

Chris, maybe?

Well, I'll get my expectations in line this weekend when I hook up with Mark. Maybe I'm just crazy.

Does anyone have any thoughts and why I didn't see any differance when I put the amp im bridge mode? It behaved exactly the same, so I think I did something wrong, but not quite sure how that is possible. It is pretty hard to screw up moving the switch all the way to the top.

The possibility exists that the amplifier is truly defective and needs warranty service.

[Mark Seaton]

Chris, maybe?

Well, I'll get my expectations in line this weekend when I hook up with Mark. Maybe I'm just crazy.

Umm... Ask the guys in the Chicago group, but hanging around with me never "kept expectations in check" for others. If anything I'm guilty of instigating many upgrades. Headroom is addictive. :roll:

Does anyone have any thoughts and why I didn't see any differance when I put the amp im bridge mode? It behaved exactly the same, so I think I did something wrong, but not quite sure how that is possible. It is pretty hard to screw up moving the switch all the way to the top.

Most amps require you to connect the speaker across the red terminals of each channel, not just off channel one. Are we wrong in presuming that's what you did? In bridged mode using a single driver vs. using a single channel on a single driver the clipping point should be quite a bit higher.

[---k---]

Most amps require you to connect the speaker across the red terminals of each channel, not just off channel one. Are we wrong in presuming that's what you did? In bridged mode using a single driver vs. using a single channel on a single driver the clipping point should be quite a bit higher.

Okay, yeah that was my problem. I questioned this last night, because the diagram on the back of the amp makes it appear this way, but isn't exactly clear. I looked at the manual, and it says a couple times to make sure the input is on Channel A, but nothing about the speakers. Last night, I guess I was caught up in a couple of things, and got confused. I swore until 2 minutes ago when I re-read the manual that it said to connect the speakers to Channel A. Maybe I'll have a chance to play with it again tonight.

[SteveCallas]

Wait a minute guys, think this through. He is reaching 120db (possibly higher?) levels of output from a single sealed sub using a 15" driver before he hears this sound. I don't think the main culprit here is the amp

[---k---]

But Steve, it should be impossible for me to bottom the driver. I only have a 450W/ch amp and it takes about 750W to exceed the excursion of the driver. And from what I understand, a driver bottoming is a very loud bang. This isn't that loud. It is a muffled bang. And the models show that I should only be reaching ~114db, so that 120db includes room gain.

I bridged the amp last night and played that scene again. It made the sound at a much lower volume level, don't remember this morning, but at my seat just the one sub was 94db. I'm not sure my testing is scientific enough to conclude it did it sooner than unbridged.

I'm going to corner Mark tomorrow and talk his ear off. and see if I can borrow or something another amp to try out.

[Ilkka]

Stevenn directed me to this forum and boy, this looks like a lot of fun. So hi to all!

-k-, When I read your thread I first thought that maybe it is your BFD which is clipping, but you said you tried it also without it and still heard the noise?

One thing about BFD though. When operating normally, those LEDs show output level. But you should be as interested about the input level too. Many of us (you too) are using some serious cuts (several -10 dB or even more) in the filters and that means that your input may be something like 2 V, but after cuts, output only 1/3rd of it. Of course then your output won't clip as easily as your input. And both are bad.

If you want to see your input level, you have to bypass the filters by pressing the IN/OUT button, so that it will start to blink (maybe 2-3 sec). Now the BFD is in the bypass mode and then of course the output equals with input IE LEDs show input level. Now set your receiver's sub out level, so that the input stage won't clip at any desired level. Yellow is allowed, but don't let the red ones lit. Then apply the filters (press again IN/OUT) and you're ready to go. Now either input nor output will clip at any desired level.

But since you already tried it without the BFD, it's not the case with you. And I understand why someone would think 120 dB at 2" would be awfully loud, but it isn't. I have self measured levels in 120-130 dB range from a single 12" vented sub at 1' distance. If you are only getting less than 100 dB at the LP, it's not too loud for a 15" sealed sub. Your room isn't that big after all. And 120 dB (unweighted) won't cause permanent hearing loss in 1 minute. :P 120 dBA might do it, but you can calculate how much that is without the weighting. Low frequencies aren't nearly as destructive to hearing as mids and highs.

I think that you are just running out of power, you are definitely not bottoming the drivers, you would notice it pretty soon. 450 W per driver isn't a lot, especially with the BFD corrections you have. You have cut everything above ~20 Hz by 5-10 dB, meaning your amp will see a FR where below 20 Hz frequencies are actually boosted by 5-10 dB. And it equals ~3-10 times power.

Get that amp bridged (wired properly between positive terminals) and use only one driver at first. You can try 8 ohm mono load (both drivers) (remember that amp sees only half of it when bridged), but I would suspect that you won't get any more than what you are getting in stereo 4 ohm (2x 450 W).

[Ilkka]

I'm turning it down.

Something is still bothering me. It just doesn't feel right. I just ran trough Avia to calibrate the sub. Playing Avia's tones with the receiver at 0 showed that all my speakers were at 85db. So, Avia's tones are 85db while the internal receiver tones are 75db. Oddly though, using Avia to set the sub, it wants the amp all the way up and the receiver level at -4 to get the pink noise the same between the speaker and the sub. LOUD! (Avia is corrected for the RS meter, right? If not, I guess that would be ~3db hot.) Playing Bella Fleck, it sounds hot. The sub level at -8 sounds about right.

I tried one more thing with the that scene in Incredibles. I put the sub amp all the way up. The sub channel was at -10. At a master volume of -12 I got the crackle. So, I turned the sub amp down a little. Same thing, -12. Turned it to about 75% and at -12 it just went away.

Steve, my chair is 9.5 feet from the face of the sub.

What does your current FR look like?

AVIA's subwoofer tone is between 40 Hz and 80 Hz, so if you have a dip there, it will mess up the calibration.

85 dB is a little bit difficult to calibrate with RS, since you will have to use the 90 dB range, because the meter's internal amp will clip at levels higher than +4 dB. That's why I would calibrate all speakers to 80 dB (use -5 dB MV if you want) and sub to 77 dB (correction for RS). Then you can use the 80 dB range and it is more accurate there too (around the zero).

It shouldn't be too hot for movies. For music many do want to use a little bit lower levels (maybe 75 dB), but that's pretty easy to do with BFD (use different memory presets).

[---k---]

Location, Location, Location!!!

I never thought I would be so glad to get bronchitis! It has allowed me to stay home the last to days, and play with my subs. (I went to work for a couple of hours today, but my boss didn't want me to get him sick right before he is about to head to the St. Thom, so he sent me home. )

Anyway, as the saying goes, location, location, location! I took a lot of measurements over the last two days with RoomEQ. Unfortunately, I didn't save a lot of them. I was doing a lot of take a measurement, move the mic and then re-measure.

I know you not going to read the rest of this, so just see the webpage with the measurements. (lots of graphs).
But, the requisite teaser, average response over 7 locations:

Image not available


Now for a few more details. Minor note, one of our leather recliners is getting repaired, so the sofa is where the two chairs normally are. Anyway, as you all have seen from my previous graphs, with the subs under the speakers, I get nasty nulls at my main seat. If I would move forward or backwards, the nulls would widen and shift. It wasn't pretty. I lacked a lot of downlow rumble, and even after calibrating with Avia, my ears would hurt at what seemed like reasonable volumes. Not good.

So, I tried moving the subs to opposite corners. I figured I would pick up more down low rumble this way, and maybe get rid of the null. Unfortunately, putting a sub in my left corner created the same ugly null as before. The sub in the right corner (which really isn't a full corner, but a weak pony wall) didn't have any down low at all. But, if I played with the relative volume of the two subs, it seemed like I could get a fairly flat response with about 25% more gain in the right sub. Unfortunately, moving forward a foot or back a foot brought back the nulls to some degree. Also, the down low dropped off quite a bit moving to the other end of the sofa.

But, it looked like the right sub by itself was somewhat even around the room, and responded to boost down low. So, I collocated them in the right corner and added a bunch of boost at 20hz. oooooohhhhh yeah. This seems like the perfect solution. WoW was a amazing experience. The sofa felt like it was going to levitate! And, the other end of the sofa was slightly less potent, but not much. And honestly, since my wife sits there, it is probably a good thing. I've been listening to Bella Fleck and not Mickey Hart's Planet Drum, and it sounds very clean still and natural. It doesn't have quite the same punch to it as before, but I think that is because I was hot up high. I might not be a good judge though, especially today with a little head congestion.

I'M VERY HAPPY.

This has also allowed me to turn the amp gain down a hair. I demoed with WoW, and saw the clip light go on, but I didn't hear any crackling. I'll have to do some more testing to see if I've solved my amp clipping problem or not, but I may have given myself enough headroom to not NEED a bigger amp (but if someone wants to buy my current one, I'll consider offers. ).

Maybe next year when I get the upgrade itch, I'll investigate building an LT to add my boost down low, rather than using the BFD. Then, I'll be adding it even lower. hehhehe

[steve nn]

So, I collocated them in the right corner

Hey thats good news Ryan...good for you! 8)

[Bent]

So, I collocated them in the right corner

is that even legal in your State? :rofl: :rofl:

You might not find this as funny as I, and I'm certainly not the worlds best speller, but I think it's

co-located

YMMV.

[SteveCallas]

I'm not seeing any graphs Ryan.

[---k---]

should be there.

[---k---]

I briefly got together with Mark, aka Doc Holiday, last night. It was mainly to copy all the DVD demo discs that are floating around. But, while we waited the 40 minutes to copy, he showed off his recently completed ported RL-p15. http://www.avsforum.com/avs-vb/showthread.php?t=657394

It is not really fair to judge his sub because he hasn't spent much time with room placement, hasn't purchased a BFD yet, and because mine wasn't side by side to compare. But, I figured I would post some general impressions - just keep the previous sentance in mind.

Anyway, we listened to:
Incredible - Plane blowing up
U-571 - Depth Charges
Titan AE
Finding Nemo - Darla Tap
War of World - Lightening strikes and the Aliens coming out of the ground
Blue Man Group Audio DVD - Chap 4 and Chap 6
Bella Fleck - Cosmic Hippo

First impression, wow, it is bigger than I thought it would be. I think he is coming in around 10 cuft. Some of you have been tempting me to build a ported sub to try out :M, but seeing how big Mark's is, has cured me of that - for a while.

I think he has some room issues. I'm not an expert, but it was obvious, something just wasn't right. I'm thinking there is a suck out in the 50 - 60 hz range. Mark plans on running REQW and getting a BFD, but he also has a newborn. Frankly, I'm impressed his wife lets him play at all with a sub these days.

His sub definitely had more low end. There was more rumble and pressure to the room. I haven't heard the Finding Nemo scene on my subs before and was blown away by it. But, overall it was definitely there and noticeable, but not several orders of magnitude more. Unfairly mixing a couple of different experiences, but I tend to remember Mark Seatons dual sealed 15" having more than both Mark's or mine. I think that if I were to get more amp and some type of L/T, either the Behringer DEQ, the QSC DSP-3, or the Bassis and I would be able to achieve most of the low end I need. -Real temptation.

At times, I thought that he might be getting more output out of his single ported than my twin sealed. His room is a little smaller than mine, but it is also still under construction and open to the whole crawlspace at the rear. So, it probably equals out. No real surprise here.

Now, I probably shouldn't talk about how it sounded, because I think it was all the room, but I definitely think my sub has more punch, more impact, and cleaner sound. Blue Man group was kind of disappointing. The depth charges in U-571 also didn't seem to deliver that snappy "bang" I remember them doing on mine from when I watched the movie a few months ago.

So anyway, Mark's sub definitely had some things going for it. I'm anxious to hear it once he gets a BFD (maybe I should sell him mine and get that DEQ.... hummmmm). We talked about getting together again sometime, and maybe I would bring one of mine over for a side-by-side comparo. We're both busy, so not likely to happen any time soon.

It was cool to get hear another sub, and get another reference point to compare. I hope everyone gets to do it. Thanks Mark!

[---k---]

Just FYI to anyone that may be interested, I put my amp up forsale in the Pawn Shop here at HT Guide. I plan on replacing it with the Behringer EP2500 for a little bit more headroom, and adding either the DEQ, a BASSIS, or custom built L/T.

[steve nn]

I plan on replacing it with the Behringer EP2500 for a little bit more headroom, and adding either the DEQ, a BASSIS, or custom built L/T.

I hope this works out for you Ryan. I'm sure there will be a noticeable difference.

[---k---]

Steve,
You make it sound like I'm unhappy. I'm not. Just wanting more more more.

[steve nn]

Steve,You make it sound like I'm unhappy. I'm not. Just wanting more more more.

Well as usual, what I said and what I conveyed, are two different things.:P