# 7 channel Seas Idunn Set



## hddummy (Mar 9, 2007)

Hello Shack. It has been quite some time since I have visited. I have been staying busy and working on the theater as time permits. If you have been following my theater build thread (see signature), you will know that I'm building a top notch, mid-budget theater in my basement. I am custom building the entire room myself....including the speakers. I always thought I wanted to do kit speakers and I was sold on the Idunn kit when I heard them at Axpona last year. They represented the perfect mix of performance and budget for me. I decided to use it for my entire 7 channel system. I called up Madisound to discuss what I was trying to do and they let me in on a little secret. The Idunn kit is great, but it gets better. Although they don't list it on their website, they have developed an MTM version of the kit in addition to the standard MT. I decided to go for it and buy three MTM kits for my front mains and four MT kits for my surrounds.

I built the boxes out of 3/4 MDF and painted them with eggshelf black latex paint. All of my speakers are hiding behind GOM fabric or my AT screen. I wasn't too concerned with having a perfect finish...just basic black that won't reflect light. The mains have absorbing foam and some acoustistuff inside. The surrounds just have acoustistuff. The mains are 44L with a 3" double flared port. The surrounds are 10L sealed.

I was shocked the first time i fired these babies up. The clarity so puts my old speakers to shame. As a matter of fact, I couldn't even use my old computer and stereo to drive these because of a terrible distortion in the left tweeter. This is distortion that doesn't even come through on my old speakers, but rings loud on these. Yeah...my old tweeters might be blown, but who cares. I dug out my old CD player and undboxed on of my Emotiva UPA-2 amps. Now that is a nice combo. Bass on the surrounds is a bit weak, but that was expected. My surrounds will be in/on-wall, so that will reinforce the bass some. The mains have a nice full range sound with a mid-range clarity that is just fantastic. Piano on these things just blows me away.

I will be running REW on them tomorrow, so I should have some response plots shortly. In the mean time, here are the pictures from my build. ENJOY!!! I know I am.

Cutting out LCR parts.









LCR parts completed









LCR dry fit









LCR in clamps









LCR in paint









My old stereo and my new stereo!!!









Surround parts completed









Surround Xovers









Surround in dry fit









Surround in clamps









Surround in paint









Surrounds completed


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## fusseli (May 1, 2007)

Very nice work! I love the look of the routing for the port flares. Lucky for you you can hide them behind your screen and don't have to worry about finishing! Are those single driver surrounds?


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## hjones4841 (Jan 21, 2009)

I agree, nice work! Wish I had the talent and patience to build my own. However, my construction projects definately have to be hidden


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## Ted White (May 4, 2009)

Fantastic job! Curious how you crafted that tapered port hole? Very nice


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## hddummy (Mar 9, 2007)

Thanks!



fusseli said:


> Are those single driver surrounds?


Each surround has a woofer and tweeter.

If you go to my construction thread, you can see pictures of my rough columns in the wall. The surrounds will be located inside of those columns after they are finished out with hardwood.



Ted White said:


> Fantastic job! Curious how you crafted that tapered port hole? Very nice


As you can see in the first two pictures, there are two layers of MDF at the port locations. I started by routing a 1/4" deep recess for my port tube to seat. I then used a 1 1/4" round-over router bit to cut the flares right into the MDF and flush with the inside of the port tubes. I used 3/16 thick, 3" ID cardboard tubes for the ports. I did two layers of primer and sanding with 200 grit to get the smooth.


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## hddummy (Mar 9, 2007)

Here are the REW sweeps for the LCR and surrounds. The red curve is for LCR and the yellow curve is for surrounds. It is funny...the shape of the two curves looks identical, but the bass is so noticably more full on the LCR. It looks like the bass region may be a few dB higer on the plot, but it sounds more than that. Also, it looks like there is a level mismatch in the surrounds. You can see at 600 where it xover to the tweeter, the level drops about 5 dB. I wonder what that is all about.


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## ALMFamily (Oct 19, 2011)

Great work Matt! :T


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## Cyberfloatie (Jun 1, 2011)

Fantastic work! Love the Suurounds... I think something like those would work well in my space if I ever get that far.


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## newtsy (Nov 15, 2011)

Congratulations Matt these look wonderful.

I built a set of Idunns a while back and think they are a great speaker.

I'm keen to build a set of these MTMs myself now.

PM sent!


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## Ile (Nov 23, 2010)

hddummy said:


> Also, it looks like there is a level mismatch in the surrounds. You can see at 600 where it xover to the tweeter, the level drops about 5 dB. I wonder what that is all about.


Idunn is crossed at 2200Hz so it's not that.

U18RNX/P woofer should have 3-4db drop at 600-1000Hz in idunn box.










Measure to higher to see what happens after 1000Hz.

Maybe your rears bit wider front baffle (?) have some effect to this?


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## Mark Holmes (Oct 12, 2006)

I really like the 1 1/4" in roundover on your port. No chuffing allowed. :bigsmile:


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## hddummy (Mar 9, 2007)

Ile said:


> Idunn is crossed at 2200Hz so it's not that.
> 
> U18RNX/P woofer should have 3-4db drop at 600-1000Hz in idunn box.
> 
> ...


You're right...i see the drop in the plot you posted. It just appeared more pronounced in my plot because of the vertical scale I was using. I'm not going to worry about it until I get the speakers installed in the wall and calibrated with Auddessy XT32. I'm pretty sure the audio calibration will have no problem reducing the signal between 100 and 600 Hz to make the overall response flat across that range.


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## Owen Bartley (Oct 18, 2006)

Matt, the Idunn looks like a very nice speaker, especially the MTM. You're obviously very happy with them, and I was wondering if you (or anyone else with experience) would be able to compare them to the NatalieP MTM or Modula MTM speakers. I doubt there are many people who have heard both, but I thought I'd ask.

Is there official pricing for the MTM kit, or is it something that they deal with on an individual basis? Is there a sealed version?

In any case, very nice work on these. The integrated roundover looks fantastic (even if they are going to be hidden away) and I like that you were able to match the set all around. Your theatre is going to sound amazing!


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## DrDyna (Jul 21, 2011)

Beautiful.


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## hddummy (Mar 9, 2007)

Owen Bartley said:


> Matt, the Idunn looks like a very nice speaker, especially the MTM. You're obviously very happy with them, and I was wondering if you (or anyone else with experience) would be able to compare them to the NatalieP MTM or Modula MTM speakers. I doubt there are many people who have heard both, but I thought I'd ask.
> 
> Is there official pricing for the MTM kit, or is it something that they deal with on an individual basis? Is there a sealed version?
> 
> In any case, very nice work on these. The integrated roundover looks fantastic (even if they are going to be hidden away) and I like that you were able to match the set all around. Your theatre is going to sound amazing!


I have not heard those other DIY kits. I don't think madisound advertises the MTM kit...just call them up. I'm sure you can build it as sealed too. I think a 20L sealed box would do the trick. Thanks for the comments!

Love the cartoon!!


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## sameoldme (Oct 4, 2012)

WOW!! nice work, so, very subjective question but how's the sound?


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## hddummy (Mar 9, 2007)

subjective indeed. I'm also a firm believer that he who chose the speakers, paid the bills and performed the labor could never give you a remotely objective answer. This is exactly why I invited two of my good friends over to do some listening tests and comparisons.










One of them brought over a pair of Zaph ZA5.2 (foreground) and a pair of Swan Diva 2.1. We listened to a lot of material and our ears were burned out by the end. My towers had the best bass, obviously. The Seas definitely had the clearest and most natural mid range, tower or bookshelf. This was also the first time I had listened to my tower and bookshelves side by side. The voicing is nearly identical as it should be. We also all agreed that the Swans over emphasized the high end. We think the tweeter sounded fantastic and possibly the best of this bunch, but it needed to be toned down a smidge. The Zaphs were just not that comparable. They gave a great effort, but the small woofers and cheaper tweeter just couldn't compete. This one should probably be used for computer or surround speakers....at least not the ZA5.2. Maybe the ZA5.3 would do better with a ported enclosure. All in all, we all agreed that my towers were the best because they performed excellently across the entire spectrum.

Please pardon the mess...it's a construction zone


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## sameoldme (Oct 4, 2012)

hddummy said:


> subjective indeed. I'm also a firm believer that he who chose the speakers, paid the bills and performed the labor could never give you a remotely objective answer. This is exactly why I invited two of my good friends over to do some listening tests and comparisons.
> 
> 
> 
> ...


Hey, I hope my house becomes a mess like that soon!! I'm hoping to start planning my HT system very soon 
Let me read the post from the very beginning to see your parts list. 
About the subjective/objective I agree that one is biased when emotions kick in :heehee: (psychoacoustics also play a good role here) but I do remember advice from an old school high end audio store owner back in the 80's, he said: "Calibrate your ears with the best and then compare the rest" he played a few jazz tracks through a McIntosh amp and B&W towers, needless to say the sound was spectacular and since then everything else I've heard is not up to par... HOWEVER I still have to hear them again and probably by now they would sound different than what I remember, so subjective and subjective... It's all in the ears of the listener in my book... But the test you made is awesome! :clap: I wish I had friends here that were audio junkies like me... I make my own stuff, never again will buy prefab but would love to test my own compared to brand name hardware...:T


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## Owen Bartley (Oct 18, 2006)

Thanks Matt, I'll look into these a little more before deciding anything. That's a good listening test you set up... as far as I'm concerned, if you can listen to a few different speakers in the same room, with the same program material over a relatively close period, you have a valid comparison. Good to know yours came out favourably.

Another quick question on the surrounds... were the dimensions provided by Madisound, or did you build them to fit your wall cavities? Just wondering if they were designed specifically to be placed in/on wall and have that accounted for in the XO as well.


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## hddummy (Mar 9, 2007)

I built the boxes to fit my wall cavities. The XO for the standard MT is designed Seas. If I recall, the XO is quite basic and there is no BSC in there. Also, i built mine sealed instead of ported, so the bass will naturally roll off sooner. I expect that being in the wall will give them a slight bass boost to compensate though.


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## DrDyna (Jul 21, 2011)

2.2mH, I'd guess they've calculated their cabinet width of 9" and added BSC. Ports or no ports won't really affect BSC too much, oversizing L1 (as most people do to implement BSC) changes the profile of the woofer at it's upper end rather than lower.

Did you run it past Madisound that you were planning to use a wider baffle or sink them into the wall?


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## hddummy (Mar 9, 2007)

nope


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## Owen Bartley (Oct 18, 2006)

hddummy said:


> nope


LOL, can't fault his honesty! I'm sure in the end there won't be a huge difference, especially for surrounds. I mean just by using the same drivers and XOs, you're probably up to about 90% (just a guess?) similarity. I certainly don't listen critically enough to pick up any differences that small, and I doubt there are many people who would,


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## DrDyna (Jul 21, 2011)

Owen Bartley said:


> LOL, can't fault his honesty! I'm sure in the end there won't be a huge difference, especially for surrounds. I mean just by using the same drivers and XOs, you're probably up to about 90% (just a guess?) similarity. I certainly don't listen critically enough to pick up any differences that small, and I doubt there are many people who would,


Yeah, it probably won't be too much difference, my guess is the mids might be scooped a little, but it's probably not too bad. If it ends up being noticeable, the best way to fix it would probably be to back off of L1 a little bit, maybe to 1.6 or 1.8 mh, but that's just a guess, it'd have to be measured.


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## hddummy (Mar 9, 2007)

We'll see what Audyssey XT32 will do with it if there are any hiccups


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## HeartFixr (Dec 8, 2012)

Your Idunn MTM build is ported but the Idun MT is not. What was your thinking on this? Not a criticism but an observation. I am thinking about the Idunn ported speaker for rear surrounds.


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## hddummy (Mar 9, 2007)

The MTM is used for the mains and will require signifcantly more bass capability. The MT is used for the surrounds, which experience significantly less bass frequency material. Additionally, since my MTs will be mounted inside of the wall, so to speak, I was looking for as small a cabinet size as I could get away with.


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## HeartFixr (Dec 8, 2012)

What are the cabinet measurements on the MT Idunn as you have built them?


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## hddummy (Mar 9, 2007)

5.375 X 11.25 X 18 Outside Dimensions with 3/4 MDF


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## GaryM (Jan 18, 2013)

hddummy . . . 

I just found this thread, and am very interested in those Idunn MTMs. I have an e into Madisound, but no reply yet.

Did Madisound provide the enclosure plans and crossovers with the kit? Or at least the crossover schematic? Could you post the schematic?

Thanks!

PS: You've had them for a few months now. Like 'em?


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## hddummy (Mar 9, 2007)

I purchased pre-assembled XOs from them, so i don't have the schematic. They didn't provide an enclosure design, so i modeled mine after the MT design from Seas. I kept the driver spacing and baffle width, but changed the the overall size and port to be appropriate for two woofers. I really like them and I think they will be fantastic speakers when i put them into full service. I had them out for about two months, but they are currently mothballed while i finish my theater room.


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## GaryM (Jan 18, 2013)

I received a response from Madisound. They sent the xover schematic, along with LEAP plots. The plots show a fairly steep roll-off on the tweeter starting about 7KHz. About 7 db down at 15KHz. That is consistent with SEAS plot for that tweeter, but for some reason it does not appear in the Idunn MT plot.

I'm not quite sure to interpret that schematic. The drawing shows only 1 woofer, though the caption reads, "x 2." I'm assuming they're connected in series. Would attach the drawings, but guess you can't do that here (only links to photos on photobucket, etc.).


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## hddummy (Mar 9, 2007)

Actually, they are wired in parallel. This is a 4 ohm kit, which is what you get with two 8 ohm woofers in parallel.


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## GaryM (Jan 18, 2013)

hddummy ---

Yes. Madisound cleared that up in a later email.

I've decided to go with ER18RNX's and the 27TDFNC/GW tweeter. Thanks for your help!


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