Ricci

Looks good to me LSC. Better to use too much glue than not enough. 

You may be the first to have one running

Parameters, notes and pics of this woofer have been posted. Looks like another good 21" pro unit so far. This is one of the smoothest modeling 21's in bandpass and horn enclosures and it directly competes against the B&C units so it will be interesting to see how it compares. Suspension was extra crazy stiff on the pair of woofers I have. Even after some break in the Fs is almost 10Hz higher than factory spec. Guess I'll have to rerun it after beating on it for a years or so. 

Awesome. Glad you like the sound. That delay setting trick works well to get pretty close fast. 

What city are you in?

It goes back to everything being a compromise. Mms is similar between the 2 which is what matters ultimately and the coil size is nearly the same as well. Copper wire of course weighs more for the same volume of material. The min impedance is 5x higher on this driver so some different choices in the wire gauge and number of turns are required to result in the higher impedance. The inductance on this driver looks good too even with the big coil. This driver doesn't have quite the same normalized motor force but its still over 300. The 2ohm version of the Ipal has a lower motor force too probably due to changes in the coil material and winding length needed. 

You may have heard...You may not. Eminence is upping their game and coming out with pro woofers that compete directly with the competition. I was able to get some early samples of their 21. So far what I've seen from this woofer is very encouraging. Specs, notes and impedance curve from one of the sample units are posted. Much more info will be coming. 

https://data-bass.com/#/drivers/5cc9adeb9b899d0004e43084

Measured parameters, notes and impedance curve for this cost effective Italian 21" woofer are now posted. 

Good post SME.

Rather than linearizing the suspension stiffness small air volumes may tend towards making the overall compliance worse in certain cases. The air inside an enclosure is a little harder to compress than expand. It gets worse as the enclosure volume gets smaller and the cone displacement gets higher. IOW higher compression and expansion and a larger differential. This asymmetry causes additional even order distortion. It may be enough to wipe out any gain in symmetry over the free air suspension stiffness. In some cases it may worsen it.

In smaller sealed cabs the BL and current induced distortion often seems to be the much bigger issue and would appear to outweigh any possible improvements in restoring force symmetry. Larger air volumes provide greater low end efficiency and with less power applied for the same output the distortion usually lowers substantially. In an IB vs very small sealed scenario like mentioned this would be most apparent. The lowering of distortion in larger air volumes would also partly be the reduction in air spring asymmetry. In general high Q alignments exhibit worse deep bass distortion than low Q ones.

Your last paragraph is spot on. Klippel is very useful but it has limitations.

As far as this STW-350 driver goes it'll be tested in a sealed cab of about 3cu ft (85L). It may be a bit less after driver displacement. I'm most curious to see what its distortion profile looks like and how well the massive diameter coil prevents thermal compression.

15 hours ago, EndersShadow said:

Looks good!  I was gonna say something about viewing in mobile..... but you guys already know that, so instead just gonna say

 

”Good Job, Carry On...”

Thanks,

Also I forgot to mention that all drivers now have measured complex inductance specs added that will allow much more accurate modeling when used with software that has the capability to use it, such as Horn-Response.

I've done some testing and the complex inductance specs can be used with the factory driver parameters even though they were measured from a driver with slightly different specs. Even if they aren't exact the sims will be much closer using them. Or just use the full set of measured specs posted here.

I forgot you got the Ipals. Sweet. 152's should be quite good in these.

Good deal. Those should work a lot better no doubt. Did you get more 152's or did you snag em out of the Skhorn to try these out?

Svs is based on the same platform but is a different frame, cone, surround , etc...

The ground plane tests on this one should be popular. 

5 hours ago, dsl1 said:

 

@Ricci - driver bolting was actually quite easy on this one. My impact driver fit nicely under the brace and the handles aren't in the way of the bolts.

I did not try putting the driver in with the handles already attached, but you should be able to do it. 

Hell yeah man. Like a glove. Did you use threaded inserts?

13 minutes ago, chrapladm said:

Wow snug fit.

Hey that's how I like it.

Driver notes and measured impedance and parameters for this 15" are now uploaded.

Sealed cabinet testing is imminent in the next few weeks. 

We still have some things to clean-up and improve such as viewing the site on mobile browsers, but we felt like we were close enough to make the switch. 

A few of the things that have changed or been upgraded. 

The format of the articles, drivers and system tests has changed. The measurements and images can now be embedded into the article rather than being on separate pages. This gives the reviews a better look and flow. The left hand side has a navigation link to jump to the measurement graphs. We may also be adding a tool to hide the paragraphs in the future.

We will be doing a better job of posting pictures and hopefully videos going forward. 

Up to 4 systems can be compared at once now via the system compare tool which will be at the top left of the page. As seen in Kyle's post above.

We have added maximum burst output in addition to the distortion limited bursts. Many of the systems tested have an additional 3 to 10dB more output capability beyond the distortion limits in the deep bass. When using a system your ear doesn't alert you that suddenly a distortion threshold from CEA-2010 type testing is being exceeded causing you to limit the volume or turn it down. That's not how it happens. This chart shows the actual maximum output recorded by the system. 

The distortion limited burst and maximum output burst tables are sortable and filterable by a number of factors. System type, whether it is active or passive, system size class, manufacturer, etc..

The maximum long term output sweep graph now goes down to 5Hz for all systems. These sweeps actually start at 2Hz but 5Hz was chosen as the lowest frequency that allowed the most powerful subs to get up out of the background noise floor. The less capable systems output will fall off of the graph at the lower limit of 70dB. 

All articles, driver tests and system tests have been gone through and reworded where needed and all of the text has been cleaned up. There was a lot of text coding errors, misspelling and punctuation errors in the old notes. I was aware of it but since we were totally retooling everything anyway for the new site it wasn't worth the effort. This has now been cleaned up drastically. I'm sure there are more errors in the new site, with the huge amount of typing involved but it will be much easier to fix those as we go. 

There are a few miscellaneous old driver tests or system tests that I decided to add from the archives. 

There are at least 7 new drivers that are going to be added in the next 2 weeks. I just have to finish and upload the notes. The Peerless STW-350 was added today. 

The testing methods and evaluation article explains how the tests are done and a basic idea of how to interpret the measurement types. This was called "Know How" on the old site. I've completely gone through and cleaned up/clarified the article and expanded it. I've also done the same with the Bass Myths article. 

As Kyle mentioned this has been a tremendous endeavor that we are excited about finally nearing the finish line on. Hopefully I can get back to testing subs this year!

I use REW its cost effective and the user interface is better than most.

6 minutes ago, jay michael said:

• Forums  I have a minidsp UMIK-1 mic on the way, been digging into

I have a minidsp UMIK-1 ordered and on its way. Been researching how to use software and the mic to align my full range tops to my newly built pair of Othorn's.  Ill be loading them into our studio space tomorrow and will start working to get them dialed in with my tops.   I'm using RCF 4pro4001's

https://www.prodance.cz/data/attachments/RCF 4PRO 4001-A datasheet.pdf

I usually cross them over at 80hz and will likely start with those settings.  Can someone help me or suggest a reasonable starting point that I can use as a delay for my tops?  I have the recommended crossover settings and eq recommendations that Josh provided and from the phase response plot posted at diy audio there is mention of 13.9ms. Not sure if that is referring to what I am looking for or not.   I have also seen it mentioned that the horn length is 3.8m long.  If I convert the 3.8m horn length considering the speed of sound I get 11.08 msec.   From what I have read and researched I completely understand this is more complicated and likely requires measuring equipment to get just right... Just wondering a good place to start to get me close while I wait the arrival of my mic.  Cheers and thanks   

 

 

It depends quite a bit on factors such as the crossover frequency and slope. The alignment type and response of the main speakers. The room, or listening environment and the speaker orientations and placement. You really do need measurement capability. It's a deep rabbit hole...

On ‎5‎/‎2‎/‎2019 at 9:56 AM, dsl1 said:

Tried some white duratex. Kind of cool.

Two boxes are done. Driver fits! May put one more coat of duratex on. The white doesn't cover as well.

I like that. I've never seen the white Duratex in person. I wonder how badly scratches and scuffs will show up?

Drivers fit! Yes! Solidworks said they would but you never know. How bad was screwing them in?

19 hours ago, Kvalsvoll said:

If you have questions about my designs, you can ask in the Room2-thread, I may even answer.

As for this specific construction pictured above here, that is not something I sell or build, this is a diy based on technical input provided by me.

Cool...I didn't translate and read the thread. I did have a brief look at your website. It appears you are selling subwoofers or will be soon? I don't care if your stuff is discussed. By all means do so, but I don't think the Skram thread is the best place for their discussion. It appears that member Alexel may have questions.

Kvalsvoll is a member here...Discussing his products for sale is kinda off topic for this thread. What he has going are not "technically" horns but that's just semantics that doesn't really matter in the scheme of things. The tuned resonators being employed are the most interesting aspect of them to me, because they aren't employed very often,  but they do increase the size and complexity of the system. Not sure I would call them compact relative to the driver compliment in the cabinets, but I would like to see things like measured impedance, voltage sensitivity, distortion, compression and group delay on one of his designs.

Looks like a reverse taper TL variant. Not technically a horn. Cab seems a little small in the pics for 14Hz but it might be. 

20 hours ago, dsl1 said:

Lol, that is close. Did you have to cut anything to make it fit?

The back mount ended up working nicely. 

Nah. It fit like a glove. The backmount in the hatch looks great. I wish I would've thought of that before you cut my hatches. Was it enough to fully recess the knobs?

3 hours ago, Jesal said:

Port and horn divider/braces are all 12mm.

I don't use T-Nuts on any of my subs, just screwed in.

If it strips rotate the driver and screw to a new area.

Works for me, I never had to rotate it yet.

Same for me. I'd prefer screwing directly into the wood. I change drivers often and do the exact same thing. If the screw holes strip I'll either go to a larger diameter screw if there is room in the driver frame, or simply rotate the driver and make new holes. This is one advantage of ply over MDF. Screwing directly into MDF is risky.

BTW good work on the cabs. That's a lot of pocket screws!

There are differences. Its a lot to go into from my phone and Ive posted about it in the Skhorn thread and other places. I'm not familiar with the linked subs or if there are measurements but its a vented sub that is smaller with what looks like less vent area and its a direct radiator. 

7 hours ago, Revolt Sound said:

Ok so it was an air leak that is causing the noise problem. It was coming from one of the un used t-nuts for the different drivers we will be testing. 

That's good news. Should be an easy fix.