Reed Exodus Anarchy 25hz Tapped Horn - Page 17

Is that distortion in dB? If so, it seems to be quite high as a %
I am somewhat new to this and am trying to compare with AT IWTS 8e Subs. How would these results compare with the AT specs that I own:

Frequency Response 20Hz - 100Hz ± 3dB (typical, in room)
Peak Output Single 102dB, Dual 105dB (3000 cu. ft. space)
Dimensions (H x W x D) Woofer Module: 19-13/16” x 10-5/8” x 3”
IN-BOX-8 SUB Enclosure: 81” x 14” x 3-1/2”

I was thinking of replacing the ATs with one of the DIY subs on this forum, but not sure if the specs are the same.

The upper line is output of the signal sweep that was sent to the subwoofer, the lower line is the distortion. You'll notice below the horns bandwidth range that the distortion like rises above the desired output frequency.

OK. So, in the range of 30 Hz to 90 Hz, the response varies by 20 dB? That's a lot, isn't it? Compare results with the AT specs that I posted previously. Trying to make sure that I get this right. Thanks

I thought that the upper line was the SPL measured. If so, that's pretty flat.

The distortion plots (green traces) are simply a measured SPL and Distortion (THD, 2nd and 3rd), all presented in dB, taken as screengrabs directly from HolmImpulse. These measurements were taken outdoors, so they are certainly not anechoic. Our noise floor was over 60 dB ambient, we were only measuring at ~90 dB. All of these measurements were collected with DIY gear, though it is not calibrated exactly, it is accurate and measures flat through the band of interest here.

The Insubnia Anarchy measured quite flat between 25 and 100 Hz. SPL response varied less than 3 dB from the average through this range.

Distortion peaks and dips corresponded to the resonances in the enclosure, as expected. Take these distortion measurements with a grain of salt though. To be blunt, distortion measurements collected outdoors are nearly useless for comparison, other than if the things being compared are all measured at the same time with the same gear. Even then, there will be errors due to variables in the environment. All I was trying to demonstrate with the THD and distortion measurements is that in a horn, once you're ~1/2 octave below the tuning frequency of the horn, the distortion overtakes the fundamental. This is simply the curse of all horns.

By the way - those "specs" you quoted are "in room" numbers, not actually measured in a groundplane environment. As a result, I can't really compare this sub to that because I did not measure things in your room and they did not measure outdoors in a groundplane environment.

An estimate could be arrived at by adding ~25 dB to the 1-watt numbers I posted. +6 dB for the room, and +19 dB for 75 watts of power applied. Based on this, the Anarchy is ~6 dB louder than the sub you referenced, while using 1/3 the power.

It is.

They are.

No, that's wrong. The distortion does, see my previous post.

Yes, it is in dB, but it was measured outdoors with a relatively high background level.

Thanks. That helps.
Clearly the green measured SPL curve is much better than the measured blue. (In fact, the blue looks terrible, but given that your measurements were outdoors it makes sense, and we can disregard it if you think that the testing conditions were far from ideal). I am not knowledgeable about the relationship between distortion and the flat response shown in the green curves between 25-100 Hz. How can one have a flat response and distortion at the same time? Intuitively, it does not make sense to me, but I am no audio engineer either.

I am impressed with the fact that you could achieve a lot more loudness compared to the specs that I posted (BTW, those are the manufacturer's specs, not my measurements) are at 12'. So, a single Anarchy would be the equivalent of the AT sub? Have you tested under more idealized test conditions?
I am wondering why one would even need four of these. One should be sufficient. Also, why would one need a Tuba HT? Appreciated your response.

A Tuba HT will go much lower and louder. Ideal for larger rooms and HT LFE applications.

We've been through this before.

I've measured both. I purchased the plans for one, and I designed the other. It is not really a fair comparison, as they are different tools, designed for different jobs.

A 23.5" internal THT vs the Anarchy TH (the Insubnia design from this thread)

Much louder, yes.

THT is +6 dB at a watt at 25 Hz, and it takes 6X the power, for another 10 db of headroom or so. So with an over-simplified, back of the envelope calculation, at 25 Hz, the Insubnia can reach ~105 dB 1M, the THT can reach ~120 dB 1M. 15 dB is a HUGE increase in SPL. It takes displacement to make bass, and a 15" driver will bring a bit more of that to the table than a 6.5" driver.

Much lower, no.

THT -3 dB measured ~20 Hz, which is within a few Hz of this design (23 Hz).

Boundary loading and room placement effects are real, and may help, but we're bound by physics here. Neither of these designs does much below 20 Hz.

Look at the scales on those plots. I can compress the scale to a similar range and get a similar shaped plot. With an 80 dB range, the 2 dB peaks and dips just go away....I chose to show the data I measured - warts and all.

The sub measures +/- 3 dB in both plots, save for the anomaly due to the measurement location that resulted in the large null at 90 Hz. It was raining, the box was unfinished, so we kept it in the garage because we did not want it to get wet....

One by itself is not that loud, really, it is about the same as a typical home theater in a box type sub. Adding more cabinets helps smooth out the room response, and significantly increases the SPL capability (+6 dB each time you double cabinets and power). Radman12 has set up all 4 in a single room. With this arrangement, he can exceed 120 dB at his listening position.

really like the small foot print of this sub.

i have a 13x23x7 room. would two of these subs be adequate? or do i need to go bigger ala THT?

thanks

Two questions:

How efficient are your mains?

Can you put them in corners?

1 - my mains are klipsch cornwall 98.5db

2 - i can put both in a corner

lilmike,

Do you think that whatever cabinet resonances occur will be reduced by the final version of the cabinet that uses dado channels and rabbited edges to hold it together.

Thanks,

Roy

Having recently "deconstructed" a pair of cabinets where one was dadoed and one was not, the strength was similar. The wood, or the joints in the plywood failed before the PL adhesive in both cases.

Neither cabinet had resonance problems (both had design and construction errors).

I can say this much - the dadoed one was a LOT easier to build. I can assemble a cabinet with dadoed sides in an hour or so, assembling one with non-dadoed sides requires considerably more time due to layout and clamping the pieces into place for assembly.

Those are very efficient mains. These are not terribly efficient subs. A pair of these cabinets in a corner will make ~100 dB at a watt if it is a good corner, and will have 18 dB or so of headroom available. That will barely keep up with one of your Cornwalls, and you have at least a pair of them.

I'd think you'll want a bit more than that.

If your heart is set on using these little subs, I'd strongly suggest two pair as a starting point.

I have a few larger designs on the way. They will do a better job of keeping up, but even something as big as the THT is -6 dB from your mains in 2pi space.

thanks for the input lilmike,

wow, even the THT is not going to be able to keep up with my mains? do i realy need to look at the DTS-10?

i am looking forward to your newer (bigger) designs.

Set your question in the context of matching the output level of the subs to the mains. In that context you can see that similar efficiencies are not necessarily required, but similar output capability is. Build accordingly.

so which sub(s) would you suggest as a better match for my mains, in terms of output capability?

Agreed 100%.

Just trying to illustrate that 100 dB at a watt is serious efficiency, and the little sub at the heart of this thread is -14 dB at that same watt. As power handling is essentially equal (100 RMS for both), further comparison was would have taken us further down that same road.

Certainly, power handling helps, but at 100 watts, you've got 90% of the dBs you're gonna get with a typical consumer-grade driver. Power compression typically sets in by 250 watts, and is present in full effect by the time you put "rated power" into a 500 watt driver.

I've measured it. Many others have too. I'm not the only one that has pointed out that the magic happens in the first 100 watts. 1W to 100 W = 20 dB. Going from 100 to 1000 only gets you 10 dB more.

Well, when fed 100 watts, your mains can do a legit 115 dB each at a meter, groundplane, and you have a pair. Remember - your mains have 15" bass drivers, and you're looking for a sub to augment that, and reproduce what they can't. In a grossly-oversimplified nutshell, you'd want a sub or subs that can add 10 dB to that number.

That's 125 dB. Since we're talking about a sub, let's eliminate anything that can't reproduce 25 Hz at 125 dB/1M groundplane.

Wow, the list just got really short.

This takes us to some pretty elite territory for a single sub. A DTS-10 can't manage that in a groundplane setting, the TH-50 gets close. The TH-221 can do it. I'm sure there are a few others that can as well (JTR Orbit Shifter LF comes to mind).

You can get there via DIY stuff too. Many ways to accomplish this, the easiest is a whole lot of 15s and a whole lot of power. In a groundplane setting, multiple THTs or similar horns could get there, two would be a good start. I have the offset-diver horn for the MFW underway, but that won't get there either, according to the simulations, 115 dB is about all it can do in a 2pi setting, so you'd need more than 2.

Thankfully, you listen indoors, in a room with corners. Boundary loading and room gain will help things considerably. If you can corner load your subs into corners that are actually effective acoustically, you can gain up to 10 dB of "free" output. That helps a lot.

A single THT or similar, in an effective corner will get you close, as will the MFW horn I'm working on. The DTS-10 in a corner will also get close. These cabinets are all large, to say the least. I have a smaller tapped horn design I am working on that will perform in this league (according to the models - again - still pixels at this stage - not plywood yet). It is about 12 cubic feet, with a ~2-square-foot footprint. A pair of these corner loaded will definitely do the trick, and will take up a lot less space in the room than the other options.

How loud do you really listen? If things are cranked wide open and you're shaking stuff off the walls, the subs had better be overdesigned and overbuilt. If you're listening at background levels, maybe not so much.

guys, first off thanks so much for helping me understand the nuances of subwoofers as i am completely new in this area.

a few things, i do have a handful of acoustic panels in the room (OC 703 2"). i should also be putting up bass traps in the corners (OC 703 x2").

i am looking for sub(s) that would supplement my mains (which can dig deep to around 40-50hz if pushed).

i typically listen at moderate level, 80-85db according to radioshack spl. sometimes pushing to 90-95db during movie sessions. not looking for permanent ear damage.

No problem. I just don't want people to think one of these little boxes is gonna hang with a 98 dB 1W set of mains at full tilt. They won't. Not even close. They're pretty good for their size, but I'm bound by the laws of physics, no way around that.

Something like a THT or the larger stuff I am working on will definitely do the job, a pair of something this size might be overkill.

What sort of floor space do you have? How large a footprint can you "park" in or near the corners? Is a taller tower a better fit in the room?

Remember - you've got to move air to make bass. All else being equal, displacement wins, and the MFW 15s that Erich has will move a lot of air for the $$$. They have the same xmax as the Anarchy, but ~5X the cone area.

lilmike, could you give some hints of these larger projects you're working on?

my front wall is taken up by the mains and center, no space there for sub.

i have a small corner on the left wall, about 5-6ft from the front wall where i can place a sub up to 36". otherwise, i have to place the sub on the back corners.

Wow! that is really awesome how u built them. There is only one driver per unit? What are the power/Ohm specs on those if u don't mind me asking.

Guys I have a question . I modeled this TH in hornresp. In my eyes it models better with the TB 1139 than with the Exodus Anarchy and TB cost less. Is there any important reason to use EA woofer? Lilmike ? others?
Chris

lilmike,

i just got 2 drivers from Eric H. right now, i think i have 3 options.

a) one dual opposed sealed
b) 2 single driver sealed boxes
c) your horn design (when they are ready)

would you say all of these options would meet my needs?

thanks

I'll PM ya to keep the thread on track