starting new MTM 2 x Exodus Anarchy + Scan Discovery Tweeter

[_henry_]

hi all,

im starting new project. The goals are :

1. Compact Size = David suggest 0.75ft3 and Kevin (the anarchy designer) suggest 1ft3 (0.5ft3 per woofer)
2. Reasonable output
3. Excellent Bass
4. Simple XO, as another woofer eliminate the bsc on this, and similar impedance midwoof and tweeter.

The proposed design was from hometheatershack forum member David Yohn.

The drivers are
1. Exodus Anarchy midwoofer
DIYCable.com : Intro » Home » Exodus Anarchy »

2. Scan Speak Discovery Tweeter (formerly Peerless HDS)
Scan Discovery, D2608/9130

David's xo designed is 12db series. the original design was with Dayton DC28F, since the Scan Discov Tweet have 93db, we need to attenuate approx 5-6db.

after running the sim it seems 30L prob good compromise between deep bass and midrange.

please suggest me anything, as this one could be fun!


cheers
henry

[gornir]

The tweeter you have chosen is great, you won’t be disappointed with its sound and performance

The Exodus Anarchy on the other hand is more of a woofer than a mid-woofer. It has a cone break-up around 3.6kHz and it shows up in the distortion measurements as 3rd order harmonics between 1.2-1.5kHz.

You need to cross-over this woofer low with steep filters no higher than 1.5kHz, preferably lower. Even though the ScanSpeak tweeter works down to 1.5kHz the “comfort zone” for both drivers at this low cross-over point is somewhat limited in my personal opinion.

My guess is that with the chosen woofer, you want to be able to play these at high spl levels and then you might run into distortion limitations. It all depends on how sensitive you are to odd-order distortion.

To know for sure if it would work, you need to do some distortion measurements at low, medium and high level for both drivers and look at the critical 1-3kHz area.

Zaph has done some measurements on the Exodus Anarchy:

Zaph|Audio

Originally Posted by _henry_

4. Simple XO, as another woofer eliminate the bsc on this, and similar impedance midwoof and tweeter.

Do you intend to build a 2.5-way? If not, two drivers in parallel in a two-way doesn’t eliminate the need for BSC correction.

It’s an interesting build and I will follow your thread closely.

Regards

/Göran

[_henry_]

actually i am concern for the anarchy breakups on 3k, kevin recommends 1.5-2.2khz cutoff for them, although he used LR4.

i do have markaudio alpair10 fullrange and alpair10bass ready for midrange duty just in case need help. but im confident these will perform well.

cheers
henry

[454Casull]

Originally Posted by gornir

The tweeter you have chosen is great, you won’t be disappointed with its sound and performance

The Exodus Anarchy on the other hand is more of a woofer than a mid-woofer. It has a cone break-up around 3.6kHz and it shows up in the distortion measurements as 3rd order harmonics between 1.2-1.5kHz.

You need to cross-over this woofer low with steep filters no higher than 1.5kHz, preferably lower. Even though the ScanSpeak tweeter works down to 1.5kHz the “comfort zone” for both drivers at this low cross-over point is somewhat limited in my personal opinion.

My guess is that with the chosen woofer, you want to be able to play these at high spl levels and then you might run into distortion limitations. It all depends on how sensitive you are to odd-order distortion.

To know for sure if it would work, you need to do some distortion measurements at low, medium and high level for both drivers and look at the critical 1-3kHz area.

Zaph has done some measurements on the Exodus Anarchy:

Zaph|Audio



Do you intend to build a 2.5-way? If not, two drivers in parallel in a two-way doesn’t eliminate the need for BSC correction.

It’s an interesting build and I will follow your thread closely.

Regards

/Göran

Even though there is a peak in the sub-multiple HD, the distortion performance of this driver is still excellent. Double them with the MTM and you are cutting all distortion by at least 3-6 dB.

[gornir]

Originally Posted by 454Casull

Even though there is a peak in the sub-multiple HD, the distortion performance of this driver is still excellent. Double them with the MTM and you are cutting all distortion by at least 3-6 dB.

I would say it’s hard to know how this woofer driver would work in the proposed design without some extensive measurements and listening tests.

I haven’t personally listened or measured this specific driver myself, but when I see the measurements from the manufacturer and from Zaph Audio, I’m a bit concerned that this driver isn’t suitable for mid-range duties even though it has impressive woofer capabilities.

But again, it depends on how sensitive you are on distortion. I myself am a bit allergic to odd-order distortion.

Regards

/Göran

[Doug76]

As was pointed out by gornir, the MTM arrangement does not eliminate the need for BSC.
Just wanted that made clear.

[RockLeeEV]

Originally Posted by gornir

But again, it depends on how sensitive you are on distortion. I myself am a bit allergic to odd-order distortion.

I haven’t personally listened or measured this specific driver myself, but when I see the measurements from the manufacturer and from Zaph Audio, I’m a bit concerned that this driver isn’t suitable for mid-range duties even though it has impressive woofer capabilities.

Assuming of course, that's what you're actually allergic to.... and the graphs aren't just biasing your experiences with other factors at play...

IMO It's a very typical metal midwoofer and I don't expect the 3HD to be audible at 1.5khz. Based on the CSD there's nothing lingering/questionable at 1.5khz so it comes down to "I can hear -40db 3rd HD" :



You do want to get that 4khz cone breakup out of the way though.

...Not high enough sensitivity to be used as a dedicated midrange but really it's no different from countless other 6.5" metal cone midwoofers. The first breakup is at 4khz. With a 1.5khz 4th order crossover (which is a good idea anyways for a flush mount tweeter 2-way with a 6 inch mid for smooth power response IMO...)

Personally I like the idea of an Exodus Anarchy MTM mated to a robust tweeter. The Dayton RS28F(or RS28A) would be my recommendation to the OP BTW as a great match to the Anarchy. The Seas DXT is another one you might wanna consider.

1. Compact Size = David suggest 0.75ft3 and Kevin (the anarchy designer) suggest 1ft3 (0.5ft3 per woofer)

3. Excellent Bass

Do you know what kind of bass transfer function do you want? Do you want lean tight bass? Punchier? Will you be rolling in a subwoofer? Sims are good but only if you've got an idea what you're looking for out of the full project. The box you ultimately go with is going to have a big effect on your perception of bass. It might be best to share the sim with us so we can help you work your way through a sim that suits your tastes.

2. Reasonable output

The anarchy midwoofers are pretty deadly if you feed them power. An MTM should have reasonable sensitivity but I'd still be looking at a nice amp capable of a nice 300w into 4 ohms to drive it.

4. Simple XO, as another woofer eliminate the bsc on this, and similar impedance midwoof and tweeter.

This is a no go. When you go with a metal coned driver, you're probably looking at an aggressive crossover to really get the breakup correctly notched. The results CAN be great (and from my experience better than with non metal cones in terms of absolute resolution though I'm always open to outliers).

Likewise with an MTM. An MTM will give you a 6db boost in sensitivity throughout the range after halving the impedance. You still need to low pass them in a way that compensates for the box / baffle step. No getting around it.

If you do a 2.5 way with a series inductor on one woofer.. you'll be back to added complexity as it is.

Simple crossovers are nice but you should never expect them. If you get it at the end of the day be happy but otherwise be prepared for anything.

[_henry_]

thanks rock.

i do have minidsp and simple measurement equipment (behringer mic + e-mu 0404). so i will get a chance to measured them after its done.

i like fast punchy bass, with modest low end, hence the 30L vol. the original designer modeled it for me. i will get back to you for the sims in few days.

i have existing enclosure, with approx 23L gross volume, need to modify the front baffle though.

please give me some idea for the baffle mods.

cheers
henry

[_henry_]

here's the photos of the cabinets. it was for Alpair10 ML-TL with external dim 47” H x 7.5” W x 6.75” D

[_henry_]

the smaller holes were intended for alpair5, hence the sealed enclosure.