Ricci

Ricci, is your listening room closed with a door or open to the rest of the house? 

I ask because in my previous room I had that bump at 6-8hz and a fairly sharp roll off below 5hz when the door was open. 

Closed door resulted in no 6-8hz bump and less drop below 5hz... 

Open to a hallway, with a tee into another short hall way and an open staircase with no door at the top. I had a rough sketch floating around at some point.

Started reading some of the DSP section of the K20's manual, didn't take long for my eyes to cross.    When you engage the peak limiter, do you notice any latency? 

I don't use limiters. My default preset of settings for the K20's is called "Wide Open". I have used them a bit before during a club type sound reinforcement setting with cabs that couldn't quite handle the full brunt and did not notice any issues. Actually I've never noticed any latency issues. I have on some much cheaper DSP solutions in a mic'd up live sound or recording type of setting. That's the type of setting where latency actually matters.

Cool graphs Bosso. Yep I've got about 12-15dB of gain by 10Hz. 6-8Hz is the sweet zone. Tons of gain there. I find that bump interesting as it has shown up in numerous room measurements I've seen from different rooms. I already had all the displacement I needed previously and the flatness of the natural room response below 40Hz is awesome. My problems have always been related to the hand off region between the subs and mains and the kick drum area. Believe it or not I ran out of headroom in that area quicker than I'd like. I was having to cut the middle bandwidth of the XXX's by a lot to flatten the response which put a lot of power into them in the 60-100Hz range with music. 43Hz peak is the placement of the seating position. Not willing to do anything there.

I mostly agree with Dave here.  While higher motor strength and higher Qts is a big benefit, all else the same, for the cost it just doesn't make sense to me.  Only if I was highly constrained by both size and available power would I look its direction.  Most likely, adding an additional amp and additional cheaper drivers (with smaller mounting depth so I can fit them all in the box) to distribute the power across would be a much more productive use of my money and would have the added benefit of demanding less excursion (less suspension related distortion) for the same output.

 The bolded part just about covers it exactly. I don't care about cost much...Size and placement is very much constrained. Not sure how a 240v home run and 2 of the most powerful amps one can buy is a power constraint though. I have no desire to add even more amps for power or wire up something like 16 15's's or 32 12's and have cabs that weigh 500lbs in my house.

Clearly this isn't a type of driver for every app or everyone. Thankfully we have a large selection of choices to fit everyone's personal preference.

Will the ports be blocked off on the inside or outside? If they're blocked on the outside, does the area inside the port get added to the cab volume?

Outside. Yes it gets added and was taken into account during the design.

I'll see what I can do next time I pull the rig out.

Only listened for a bit so far. Sounds basically the same as before. Perhaps a little better through the crossover but I haven't pushed it at all yet.

Josh, what will you use to EQ your subs if anything?  If you get a chance on your next measurement session will you show the close mic next to the LP response?  That is some wacky looking room gain below 10Hz.

DSP is built into the amplifiers. Advanced stuff can do custom Bi-quads, limiters, etc...Detailed literature if you are more interested is at PS website.

Signal chain is PS3 source, Onkyo 886P preamp, K20 amps currently.

I did a very rough EQ last night. 4 filters. They need optimized better. I just wanted to listen to the bass system after working on it for 2 months straight and most of this weekend, so I called it good and watched Avengers Age of Ultron RB'd and Kon Tiki last night.

Here is about what the room gain profile translates to compared to ground plane. I've tested about 10 powered systems in room versus ground plane and the average gain in output at 20Hz is roughly 3 to 4dB to the LP. This should be close. Tons of gain below 15Hz.

There's a bunch of ways to skin the cat. Lets be honest here 8 of the HT15's or 18's like we heard at Brandons place are overkill already, unless you are well past any sane playback level. I've been interested in pushing the limits of what you can get from a certain amount of volume with cost be damned for a long time. Most of my designs including my horns are along that train of thought.

I always liked the xxx's simply because they could be beat on with a severe amount of boost and you really didn't have to worry about the excursion. The amp almost always gave out first. Every other driver I tried wasn't quite there. Then the new Sundown parts came out, but that was well after I had the x's. Probably would have went with something based on their team or Nightshade platforms if they'd have been out at the time. Anyway there's nothing budget or perhaps practical about the bass systems I use. I never recommend them to others.

The room gain is certainly there but the amount is a bit deceiving. There is a large amount of gain below 15Hz and also at the 43Hz peak. Up top it is actually a bit of a net loss. Still there is a ton under 20.

Something funky happened to the SPL numbers for this driver in the systems list.  They're all blank. 

That's very odd. The data was missing. Not sure how that happened. It's been uploaded. Should be there now.

Shoot...It is exactly what I've been looking for. Different strokes for different folks. I've slowly gravitated towards low q drivers and sealed systems over the years. The problem is most of the drivers don't have enough displacement. This one does. With enough motor you achieve slightly better than 12dB octave rolloff. Less steep, not more. If you compare this with other drivers in the same box you can see this effect below 30Hz. Drivers with lower motor strength per unit of cone area have a hump in the response and a sharper than 12dB octave roll off over some parts of the bandwidth. Drivers like this are slightly shallower slope in final roll off. The F3 ends up much higher but that is irrelevant. I prefer that. That is the effect of much better efficiency and ends up being much higher headroom, efficiency, sensitivity, etc. Less power demanded from the amp and better headroom with complex signals. The 24 is very cool no doubt but not enough motor for me. Needs a big boy motor. BHS is a step in the right direction. Boxes are too big for me to run it as I would want to. I'm running a pair of these RF's in a box about the size of Dgage's single 24 and the system qtc is extremely low, near IB. I don't see how mounting depth is prohibitive either. Yeah it's REALLY deep but it will still go in a box 19" deep without issue. Mounting depth needs 16". I don't see many people building 18" drivers into boxes that are less depth than that.

I'm working on getting the system back up and running today and here is the raw at the seat response with no smoothing and no signal shaping. The LPF is in line. This is a much better starting point than the XXX's, which exhibit the typical inductance and high qtc hump which exacerbates my room issues.

There aren't enough speakers in that room.  Not even close.

 

JSS

I don't know, he may be able to reach Ref level with what he has.

Comments and discussion go here...Just put the measurement and driver notes up.

I have my new 18" and 21" vented cabs in which will be used for testing the occasional driver. Thanks to Nathan Funk for building those. The design details are as follows.

Both are void free 18mm BB ply. Both have a deep 3.5" recess from the baffle to the front of the cab so a steel grille will clear even the tallest surround, longest throw drivers. The baffles are double thickness. Bracing is simple but is a large cross brace connecting the sides, top, back and bottom of the enclosures. The vents are 3 large slot ports on each. The plan being to be able to run the cabs with any combination of vents open or with all blocked as a large sealed. These cabs are pretty large in order to work well with as wide a range of drivers as possible. Those having moderate to low motor force will matchup a bit better for the most part and those having higher motor strength will end up a bit peaky at the vent tune. Another reason to make the internal volume a bit bigger was to get as large of a vent area as practical while getting the tunings into the range wanted. the plan was one port open being a typical low HT tune of near 16Hz, 2 ports open being a more usual versatile tuning of around 23Hz and with all ports open something closer to what a pro audio or car audio cab would have at around 30Hz. I couldn't quite get the full spread of tunes I wanted but as we all know it's about the compromises. It will be interesting to see what the tunings actually come in at. I suspect a little lower than calculated.

 I'm not going to test every driver in these cabs. It would simply take WAY too long. The sealed cabs will still be the default test boxes as that is the simplest most effective way to compare driver for driver. These will be used with the occasional driver that does very well and will provide a comparison to the sealed data and how the vent, bigger cab and or different tunings affect its performance. Then educated guesses can be made about how these things would affect other drivers.

18" enclosure is 35.5"D x 30"H x 22.5"W

The vents are each about 34.5" long (Depending on the loading of the internal opening)

The cross section of each vent is 170.5mm W x 125.5mm H (213.83cm area each)

All vents open 233L Net (29Hz tune) (641.5cm of vent)

2 vents open 251L Net (22.7Hz tune) (427.66cm of vent)

1 vent open 269L Net (15.5Hz tune) (213.83cm of vent)

All vents blocked 287L Net

21" enclosure is 36" D x 30"H x 24.5"W

The vents are each about 34.5" long (Depending on the loading of the internal opening)

The cross section of each vent is 187.5mm W x 130mm H (243.5cm area each roughly)

All vents open 255L Net (29.6Hz tune) (730.5cm of vent)

2 vents open 274L Net (23Hz tune) (487cm of vent)

1 vent open 293L Net (16Hz tune) (243.5cm of vent)

All vents blocked 312L Net

Looking forward to seeing how the NS18 handles your torture tests! Problem is the flange is a bit bigger than the open tool 18" baskets, so you might have to do a new baffle.

I can already tell it is an extremely low distortion driver. Impedance curve alone says that. It does have quite a bit of excursion too. Still solid by modern standards. I am a bit worried about the single layer, short coil during the high power tests. I really don't want to damage it. It's such a nice looking driver.

I hope you realize what you've done.  Inviting Scott to your house is like inviting Gary Busey after a 3 day cocaine and whisky binge and I've spent the last 15 years modeling my behavior after a mixture of Rick James and pre-rehab Robert Downey Jr.

I've also got a Dayton UM18-22 for grabs. Brand new, the box has never even been opened.

$240 shipped.

The only gigs the BMS's did was as part of a bass guitar rig. Not much of a challenge for them. They did sound excellent though.

They have the usual marks on the motors and frames from mounting them and moving them around.

... internationally?

Negative captain. These weigh about 115 lbs each in their factory packaging. It costs between $100-$150 just to ship each of these within the states.

Nice looking room LaHatte.

Updated for sale list...All equipment is used and may have a few cosmetic blemishes but is otherwise in correct functional shape.

2 XXX 18's left. $550ea shipped or $500 each local pickup. I will drive to meet.

Chane SBE-118 and a Chane VBE-118. Both are passive cabs with a single 18. One sealed the other vented and tuned to the 17Hz range. Local pickup only. $185 each. I will drive to meet.

BMS 18n862 18's. 1 pair. Low distortion with excellent all around performance. $450 each shipped. Local pickup fine too.

Gjallarhorn pair. The originals. Loaded with LMS Ultras. $1150 each or $2300 for both. You will need to setup freight shipping, schedule pickup and pay all shipping costs. It won't be cheap. Local pickup greatly preferred. I may be willing to deliver if within reasonable driving distance and travel and gas expenses are paid.

I do listen to a lot of music in the garage while working. fairly subdued volume levels though. A couple Dayton 15's would probably get it done really.

I actually do have an attic storage space above the garage that would work for an IB. Hmmmm.

Nah not selling all that. Just reached a point where I realized Id like to get some space back.

Still 2 18" XXX's left. Somebody grab these!

Right now my garage is a train wreck with multiple projects going on and crap everywhere.  I was looking around in it yesterday and realized I REALLY need to liquidate more stuff.

This is what is currently sitting in my garage.

6 XXX 18's

7 TD15M Apollo's

2 BMS 18n862

1 LMS 5400

1 Alpine SWR-1522

4 21Ipal

1 Aura NS18

A couple other random drivers

That is just what is mine.

There's also

1 SI 24

2 SI HST-18's

2 other 21's to be tested for a Mfg

1 Other 18 to be tested for a Mfg

There are drivers, subs and boxes everywhere.

^^^ Never thought I'd be going to buy that movie...

Werd...

Just added up the driver specs for a few new drivers I have on hand.

Aura NS18

Alpine SWR-1522D

SI HST-18d2 rev 2