Ricci

Update: I've got a lot of things coming up...Here is what will be measured first and in what order and what I can talk about currently.

1.) SI HS-24 (15cubes sealed)

2.) Dayton UM18-22 (Sealed)

3.) MTX 9515-44 (New larger 15" sealed test box. I've been needing that for a while so I can start doing more 15's.)

4.) Jeff from JTR is coming in one weekend in May and bringing some of his lineup.

5.) Reaction Audio is sending at least an Echo-18 when they get things rolling with the new amps and all that.

6.) Fi Car Audio 18" SP4 is being sent by a member with some shipping help by others.

7.) I have an Orion HCCA-152 on the way.

8.) 21IPAL's...

There is more that is either in the works, or that I shouldn't talk about just yet. I have designs for vented cabs with variable tuning in 12,15 and 18" sizes that I need to build or contract out. PaleHorn cabs. I'm also reaching out to a few manufacturers who have drivers that I think may be sleepers, or are popular, or represent the cutting edge and am inquiring about samples for performance testing. We'll see how that goes. I expect most to blow it off but perhaps not. The main amplifier will now be a K20-dsp which on paper offers an additional 1.5dB of headroom over the K10, whether any cab will ever make use of that last 1.5dB is questionable but hey it's there.

Yes it would be expensive to repair. Shipping 100lb amps is not cheap. Fans are loud yes. Input sensitivity specs should be listed at AeTechron along with schematics, etc.

That's a great deal...if I remember right they will do 1 ohm as well.

Note the scale on that graph. Not much of a bump. Probably a measurement artifact.

That AETechron 7560 looks like a beast!

Oh they were. NO low frequency roll off on those. They were supposed to be good up to 70kHz or something like that as well. I kind of regret selling the pair I had. But they were 5 rack spaces tall and 100lbs each and really needed a dedicated 20A line to each. Would've been great for mains or an IB system.

I do have a few more loopbacks I can dig up and post I just have to figure out where I put those measurements.

I still use a Presonus Firebox for most. I have 3. They are about -1dB at 8Hz and -2dB at 5Hz. Small, reliable and built like a tank. I have tried to find something else that perhaps measures a little bit flatter even than that but run into problems with headroom in the mic preamps with everything else I try.

The Firebox allows SPL calibrated measurements of right about 140dB using Earthworks M30 or M50 mics before clipping the preamp with the input trim bottomed out and a bit higher than that if I use the ACO rig, but to be honest after doing direct comparisons of the ACO rig versus the EW mics the only differences I could spot worth even mentioning were below 5Hz and they did not amount to much at all. Very close. I usually use an EW because it is a bit quicker and easier to setup due to less cables and one less ac plug. Most of the other interfaces including others from Presonus, M-Audio, Tascam and RME that I've tried just don't accept signals that hot and will clip when the levels reach 120-130dB. For most this wouldn't be an issue but I need the headroom and would have to switch to different mics or add an attenuator to get headroom in the measurement chain. Little bit different priorities for me than most other guys.

I'm still hoping to find something a bit better but I have been lazy lately.

Tons of loopbacks.

Note that on a few of the measurements you will see a sharp drop off or spike up near 20kHz. Those are artifacts due to the limitations of the measurements sampling rate and not part of the devices response.

EQ Devices:

 

M-Audio Mobile Pre

 

Presonus Firebox

 

 

Mixers:

Peavey PV-14

 

Outlaw Audio Model 950 SW Out

 

Onkyo TX-SR806 SW Out

 

 

Amplifiers:

Crown CE4000

I hope to start back up in the next couple weeks if I can get a few sunny days. It is going to be a very busy 2015. First up will be the SI 24 and the Dayton UM18-22.

Of note is that the first UM18 I was sent had a bent and cracked frame. The box did not seem to have any damage that would indicate that this type of heavy damage could have occurred during shipping so it leads me to believe that this defect was in place before it was even boxed up. Dayton responded quickly and shipped out another one which appears to be ok.

After those 2 drivers are tested I am going to do another MTX 9515-44 sealed test with a newer and larger 15" box of about 3ft. This will be a nice comparison to the testing done with it in the tiny 15.5" cube previously. I expect deep bass sensitivity to go way up, burst output in the deep bass to go up and distortion to drop dramatically also. Vented and sealed testing of the AE TD18H+A will be coming. I will be doing a few amplifier comparisons using test signals into various speaker loads also. I have some new cabinets that I will be building and testing with Powersoft's IPAL module and control system. A number of commercial powered subwoofers are already scheduled to be coming through as well but I am going to make an effort to get back to the DIY side of things this year which is more in the spirit of what started this to begin with.

That is a pretty good price on a 9000i. That amp should be close to a pair of XLS 5000's on real world content, even if it may not be quite as capable of being used for welding. I doubt you'd have the circuits required to weld with a pair of XLS 5000's anyway. I don't know the roll off for sure but Crown has seemed to favor a 8Hz DC filter for their lightweight amps in years past. It should be -3dB at 8Hz at dropping rapidly below that point.

The amp part is not finished yet either. Working on getting an M-force module. I may try and get one of the woofers at some point but I think PS kind of missed an opportunity with those. Already own one IPAL module but I don't have it yet either. Things have been really busy this winter and I just haven't had time to get to everything.

Yes it is a similar fold style to the GH2. Actually the PH fold was done first and gave me the idea to try it on the GH. I'm hoping to start on my cabs soon. So far the PH's are vaporware. That will be remedied this summer.

I had to send both of them back after receiving them, then one of them an additional 2 times. They had a defective batch of coils from the vendor. One blew on very little power twice, one was scratchy right of the bat and the other had a very odd issue with seemingly working ok but presenting nearly a dead short to the amp. There was no impedance peak indicating resonance on that one! I just got the second driver that has had constant issues back and it seems to finally be good, so I now have a working pair of TD18-H+ Apollo's like 3 years in. This was all on John's dime BTW. I paid nothing for all of the shipping. He probably lost money on this pair. What a journey.

We use them for our bass guitar rig. At this point I'm scared to do a DB type measurement battery on them because they might let go and I don't know if I can take it again. John will probably commit himself to a mental asylum if I contact him about them again. They do sound great but I wonder about their survivability now.

Just keep in mind that most of what we listen to is very transient in nature and really doesn't amount to anywhere near the average current that you may think. Breakers are rated to trip at a point that approximates an average current draw equal to their rating. They will pass many times their rating for brief periods. An average current draw of even 20A is a ton of power into your subs. If using a 30A 120v breaker, you will have to draw a huge amount of current in one brief peak or a very large amount long term to trip it. Also keep in mind that once breakers trip a few times they will become easier to trip over time. If you have a breaker that trips easily it may be worth replacing with a new one of the same value.

^{Update: I finally got a hold of someone and DaytonAudio and they sent me a UM-18-22 so that will be getting done after the big 24 this spring.}

Well...If you just need power I'd look out for deals on some of the pro sound boards. A QSC PL380 would be great. Those go deep and are rated at 2500w per channel at 4 ohms and 4K at 2 ohms. Class D. Sometimes they come up for sale in the $1200-$1600 range. Crest Pro 9200 is decent too again they go deep. Those come up for sale around $1100-$1400 too. Sometimes you can find a QSC RMX 5050 for around $850 if you look hard. All of those amps are -3dB at about 5Hz or better. I'm just not a fan of the Sanway or other Chinese copycats personally. I would definitely get Dave's vetted and tweaked version if you want the 14000. The others are far too much risk and seem slapped together with whatever parts are on hand for my taste. The bit of extra money for Dave's version is going to be worth it in the long run. IMHO of course. The SpeakerPower amps make big power but the budget is starting to get up there for those. I did verify that the roll off on the 12000 I have on loan is about -3db at 4Hz.

Budget?

Its just the fact its a 21" driver with 20mm xmax in a horn tuned near 25Hz. Takes a lot of juice to get the cone to move that far at the excursion max near 38Hz.

Yep. Dual hatches are a must in order to easily get at all of the bolts for the driver. It just fits through the hatches with a bit to spare. I usually like to leave room for potentially bigger drivers in the future but on this one rated xmax isn't even reached unless you have a LOT of amplifier. The Othorn would already handle a big amp and this takes quite a bit more to push the driver to xmax so this one will likely be thermal buildup limited more than anything. I don't see any drivers handling more than this one thermally and extra xmax beyond what the ipal driver has simply won't be used because you won't be able to get enough amp on it.

I read through some of the 24 discussions over at AVS. Speculation city. I'm going to make sure it is my first outdoor test of 2015.

Close guess. I sort of mentioned what was going on in this cab already. May as well post the fold pics.

The 24 was in the exact box that you apparently just received! I would suggest if you are able to, double up on that front baffle if at all possible. I built that out of wood I had left-over from my corinthian buildout and didn't have enough to double up. There is certainly room to stick some ports. likely in each corner. The internal bracing is:

 

 

We were definitely not trying to absolutely kill the 24 that day, as Austin had plans to take it and his other one to Qatar with him when he left last fall. We were literally just trying to find the limits of the sub, but not attempt to do permanent damage. We certainly could have easily killed it, but excursion limits in a 15 cuft sealed box with standard dubking content proved to be futile. Austin is actually doing a 35cuft or so ported build as we speak, tuned to near 11hz IIRC. One box will be behind his couch and the other under his TV. Should provide for a pretty fun/intense experience. 

Thanks for the pic. Might be difficult to get ports in there but I will see what I can do.

I see now that you guys were just playing it real loud with some music. It takes a crapola of power to bottom most subs with regular old music. The stuff just isn't low enough. So far the 24 seems real rugged mechanically. I think burning the coils might be a bigger issue with too much power on that woofer.

Haha...Yeah it was Mark that told me that. I didn't even know about it. I don't think the amp was near clipping either.

Content and crest factor is everything. You could run the amp up to clipping on the peaks of something like Metallica And Justice for All for hour and the sub will probably be fine. Other content not so much...Guys like Mark have to assume there is a dumbass out there who will turn the system up to the point the amp is clipping full time with a compressed dub or techno channel and just leave it running like that for 6 hours. If it won't survive that or similar he can assume there will be warranty claims from said dumbass.

Are you sure the guys were trying to kill the woofer? I don't advocate doing that type of thing but it sounds like the guys might need a lesson or two if they can't get it done with an 8kw amp!  J/K

On the serious was the driver in a box when this took place and how long was it subjected to the music or whatever?  

BTW Beast I just received the box for that driver from Nick this week. I think it used to be yours? I've got plans to dig into the guts and see if I can cram 3 or 4 6" ports in there too. Might as well while I have the big woof. It won't be 40 cubes but the modeling does seem to indicate some good gains just in 15ft.

Only curious as I have played with the 21 IPAL in many simulations but Ricci what do you think this driver can take as far as compression?e

I'm not sure. The cone does have a reinforcing ring about 1.5" wide around the cone edge which the 21sw152 did not have. That should help strengthen the cone edge where flex would be worst. We will see. If it survives the PH cab testing with a BIG amp strapped to it I suspect the cone is good for pretty much any loading. We will see though. It might grenade at high power too.

John,

You give me too much credit. I like to keep things simple where I can. I could not fit a true throat chamber into the design because it complicates the fold and takes up extra space. I may try the cone correction plate but last time I did that is when I did crack a cone so I'm a bit leery of that. The improvements where there but they weren't game changing. Ultimately I left them out of the Othorn for that reason.

_{Figured I might update the old amp list.}

_{Mackie M1400i Repaired still powering JBL compression drivers
Behringer EP4000's  (Sold) Long gone...
Crown CE4000's (Sold) Long ago
Crest 8002's (Still have 4 of these.) Still a great bass amp. PFC! 66lbs, basic black, no light show.
QSC PL9.0's (Sold)
AETechron 7560's (Sold) Sort of wish I'd have kept these now.
Powersoft K10's (Sennheiser KPA2400's) / Sold...And going to a good home}

_{Behringer Inuke-6000 non dsp}

_{(Bought this to see what $400 could get these days. it does have a good amount of power but the old Crest 8002's are rated at only 4kw yet seem to be quite a bit more powerful on big subs. Tried it on full range duties and did not like how it sounded in the upper midrange and treble. Tried it on full-range bass guitar in place of an 8002 and thought it did ok but the guy playing bass said it sounded weaker and the tone was different. It's his call so that was swapped back out quickly. Then tried it on a stereo pair of GH's and it abruptly died. It was not being pushed hard at the time. Got it replaced under warranty. Moved it to mid-bass duties covering 70-750Hz wired at 8ohms stereo running 4 very efficient 15's and it has been fine ever since. Overall I was a bit disappointed in the amp. It felt very cheap, was ugly, gaudy lights, blew up once, and didn't seem to sound very good except when used below the mid-band. Plus the fans are really loud. The best thing going for these is the DSP. Still a great bargain for the money but I'd look to other amps if the DSP isn't needed. Sorry if I offend anyone with this but that's my impressions of it. I am a bit spoiled in the amp department though.}

_{Dayton PSA-1000/SA-1000}

_{I've reviewed a number of subs using this amp. Offers a pretty good amount of power for the price. Has a nice range of adjustments on board. The built in rumble filter is easily modified or defeatable. I wish they had an XLR input. (I avoid RCA's like the plague, virtually none of my equipment uses them.). Gain is crazy high on these. Can be a bit noisy due to that if care isn't taken with gain structure and grounding. One other thing of note is that it appears that these are allowed to go all of the way into hard clipping rather than employing a clip limiter, which will generate a lot of power but lots of distortion as well. Not really a big deal in the scheme of things just something a bit different from most other comparable amps. Wish list for this one would be a speakon connector on the rack version.}

_{Emotiva XPA-5}

_{Class D, SMPS amps have come a long, long way but they still seem to sound a bit harsh in the upper mids and treble to me. The Powersoft K series is about the best sounding I have heard run full range but I still like older school amp technology for full range or upper bandwidth duties. That is why I bought this a few years back. I really like this amp and think the Emo amps are a pretty good bargain for the most part. No fans to worry about, XLR inputs, very well built weighing near 70lbs and it offers plenty of dynamic reserve for most situations. I wish they would dump the silly consumer audio connections like the IEC detachable power cord and go with powercon and add speakon outputs. I also wish there was an adjustable input sensitivity as well, but still for the $800 I paid it's been a nice amp.}

_{Speakerpower SP-4000 plate}

_{These are the real deal. Brutal amounts of power in a plate amp. More than most single or even dual drivers will be comfortable with over long periods unless some long term limiting of current is invoked. I know in one case a driver, that many people brag about as being able to handle the biggest amps around without issue, was summarily torched and the coil turned into a burnt slinky in short order on one of these. No it was not by me! Very simple layout too. Only thing I wish it had was a more user friendly DSP interface and system.}

_{Speakerpower SP2-12000 see the SP-4000 comments and multiply by 2. This is a very powerful amp no doubt. One of the most powerful on the market. I like that the fans won't turn on until the amp starts to develop some heat which takes a bit. Nice and light weight too. Very efficient. The version I have has the input trims on the front panel thankfully. Having them on the back would have been a bit awkward so I am glad that move was made. Much like the plate version I wish the amp had a more user friendly dsp system. I also wish that there were a few other things such as universal voltage capability and bridge capability (for those times when you really need to let your Danley TH812's loose). Also the amp looks rather pedestrian. I'm not a huge aesthetics guy but this is a $3.5K amplifier. On the amp I have there are grounding wires to the chassis and adhesive that can be seen right through the front grille. This is because there are no air filters?! That seems a bit odd to me because the grille slits on this amp are quite open and it does have fans. I would think that without filters that all manner of dust and debris may easily be pulled into the amp in short order. Maybe they just weren't in place in this loaner amp. Minor gripes aside this thing makes huge power. There is no doubt about that. It seems to handle 2ohms nominal pretty easily so far as well. Also for anyone wondering I measured the response of this amp and it is -3dB down at right about 4Hz. Good enough for the bottom dwelling IB and sealed power users out there me thinks.}

_{I also have a few new amps I'm working with or will be working with soon. I've got a Powersoft K20-DSP or 2 on the way, I should have an M-Force module soon and also an IPAL module.}

_{Lately I've changed my tune about dsp being built into the amp. I used to not care. I'm starting to realize that the more cables and power cords I have to run the more complicated and messy things get. I'm a fan of condensing things into as few electronic units as possible now. With that said I wish someone was making old school torroidal power supply amplifiers with DSP front ends and large channel counts. Does anyone know of any? I would imagine there aren't because at that point you are blending consumer/ "HiFi" with professional traits. I mean you have Lab Gruppen PLM20000Q's and such or Powersoft's new X8 8 channel amp with DSP but these are $10K amps.}

Mine came with a 30A powercon and 10/3 with a 30A 250v twistlock plug. Sure yours wasn't 120v Luke?

Hey John,

I’ve done a lot of thinking on it, but I still have many unanswered questions myself. For one thing observance of polarity at the driver connection and placement of the DPC sensor are both critical. Otherwise system stability issues can result. Polarity must be reversed in the software if needed. This gives a clue. The system tracks the input signal, the output voltage, the output current, back EMF from the driver and the pressure from the front of the driver cone at the baffle. A great many things can be calculated from this information when combined with some user input data such as driver parameters, SD, RE, MMS, etc... Impedance, peak and average power applied, driver excursion behavior, probably impulse response, etc…Can be gathered.  All of this information is gathered and electrical feedback plus the DPC sensors acoustic feedback can be compared back to the input signal in nearly real time. Let’s say that you have a tapped horn with all of the crazy impedance spikes and resonances inherent to that type of design. How could the IPAL feedback possibly work with that type of system and know what the system is supposed to behave like? Let’s say that the input signal for a kick drum comes in and the fundamental is near a resonance in the TH pass band at say 70Hz that would typically ring. The IPAL system can sense that there is significant difference in the buildup of pressure near the driver and ringing after a “perfect” reproduction of the input signal would have stopped and can adjust the driver cone movement to better match the actual signal and dampen the ringing somewhat. This is how I think it would also damp ringing of ports a bit. It isn’t perfect obviously but their measurements do show that it makes significant improvement. I’m still trying to piece together other parts of what is going on that allow it to work with vented and horn systems.

As far as the TSP modeling aspect. I will probably not use this aspect much. It is interesting but not what drew me to the technology. Sure you can modify the driver behavior but like anything else it is still subject to the physical limitations imposed by the amplifier and the driver and cabinet it is working with. Basically you cannot force a $200 18” pro woofer to perform like an IPAL driver. You would come at it from the other direction with a really strong driver and dumb the parameters down a bit to make it have response like a more traditional woofer design and cabinet. You can make the IPAL drivers respond like an Eminence Omega pro in a 7ft vented cab, but you would not want to do the reverse. Basically you wouldn’t want to force a driver to act like it has a more powerful motor, or lower qts than it naturally does.

Compression ratio I am still going back and forth on...Yes it is even more aggressive than the Othorn however the driver could potentially have 3dB greater excursion limited output and higher power handling. All of which pushes things even further. Folded up cones or massive compression could be a real issue. However increasing the throat volume loses a lot of sensitivity and makes the response much rougher. 6 of one half dozen of the other. I've been doing a lot of second guessing. I will have to make a move and go for it in the next couple weeks if I want the cabs done in time for spring.

BTW if you can guess what is going on in the cab I will give you a cookie.