Old engineer new to HT DIY needs help spitballing on-wall project.

[Thoth]

OK, so here’s the deal: I am a semi-retired engineer who loves DIY home improvement and tinkering with new things. I’m also a fairly competent woodworker, and all those things have collided recently in a project requested by the wife (hereafter referred to as “CEO”). It is a fairly ambitious floor-to-ceiling fireplace surround / built-in entertainment unit that will incorporate the TV and the main HT speakers. Here is a (very quick) cartoon of the wall showing the gross parameters I am working with (I hope that I'm inserting this right):

UPDATE 9/12/2014: After lots of great feedback from ---k--- and cjd, I've tentatively decided to build versions of the Khanspire and Khancenter designs into the fireplace unit as shown below. These guys have been great and the designs look fantastic ;x( I'm really looking forward to this project and have already started a new build thread for the center: http://www.htguide.com/forum/showthr...rround-Phase-I.



Note that I tend to work in metric, so I apologize in advance if that is a problem. Also note that the total depth of the finished unit from the wall will be limited to 30cm max (but we do have 2x8 walls so I could theoretically recess another 20cm if somebody has a diabolical idea). All speakers will be built into the unit – not resting on shelves – and can occupy any portion of the space allotted. The center can go in either above or below, and I will shift the TV space accordingly. The subs are already built and installed, awaiting the rest of the cabinetry around and above. Building the subs is what really got me interested in DIY speakers to begin with; I decided to gut a pair of Pinnacle PS-225 12” units that I picked up cheap a while back. Designing the new boxes taught me a lot of basic principles, and I am proud to say that they are definitely an improvement over the factory originals. But of course subs are easy, and when I started researching the rest of the system I realized I was way over my head.

I would love to just tinker with various designs and arrangements until I get it right, learning and having fun along the way, but alas the time I have been given by the CEO to complete this project is finite; whatever I do needs to be pretty darn good the first time because I am going to have to live with it for the foreseeable future! I also know that the general pros and cons regarding HT speaker placement (center above or below screen, etc.) have been discussed at length, so I don’t want to waste anyone’s time with a rehash. Just want to ask folks with lots of experience what they would choose in this particular situation.

I know that there are literally hundreds of MTM (or various combinations of M and T) designs out there that would probably work fine for the L/R, but I assume that most would benefit from modifications for baffle step correction to make them suitable for what is (essentially) an on-wall installation like mine, and I am not ready to tackle the crossover redesign without a LOT of help! Besides, I like the idea of doing something unique – as long as it has the tentative blessing of people who (unlike me) actually know what they are doing. I also don’t want to just do a “kit” – anybody can follow directions and screw parts together – I want to earn it.

I must say that I love what I read about the Ansonica design by CJD (who appears to be a giant in the field) and more specifically the Anarchy drivers used in that build. I understand that the Ansonica is intended as a floor speaker and would probably not be optimal when squared up, raised to my required height, and built into an on-wall configuration. Would there be some reliable variation that would get them better aligned at seated ear level? Maybe invert the entire design and make the enclosures straight? What about the aforementioned baffle step correction? Some other design using the Anarchy? Am I just saying stupid stuff here?

Looks like I’m probably limited to 4-5” drivers and horizontal arrangement for the center. I have read the many discussions on “slim” center channel design - particularly regarding off-axis performance and lobing – and realize that I must compromise. Our habits do not involve extreme off-axis listeners as a rule, so I’m really more interested in having something that helps where it can and doesn’t do any harm. I also know that there is a large contingent in support of not using a center at all, but I think I want one if for no other reason than to claim that real estate in the name of audio! I found the Cynosure design at PE and was about to order the parts when I decided to slow down and get some advice. The fireplace puts the TV so high on the wall that I’m assuming the bottom placement would be best – it is essentially right on seated ear level.

Whew! If you read this far, thanks! I’m sure that I will need to provide more specifics before anyone can give useful feedback, but the post was getting too long already and I didn’t want to include a lot of extraneous info. Any and all questions, advice, help, or comments are GREATLY appreciated.

[cjd]

There are a handful of other in wall designs out there, but im bad at keeping track.

Can you bump the TV up or down to gain 5-10cm? Down would be best sonically... No mantle causing reflections at bad frequencies.

The in-khan or my HT mains would do well here, and the khancenter or arbourio could match well center-wise but both need a bit more space. Note different tweeters, but they match sonically reasonably well.

I only have a surround variant of the Ansonica that would do well in wall at this point. I'll be working on a new 3 way soon, but hadn't planned in wall. It leaves you short on the center too, unless you can wiggle a bit more space.

Somewhere after (or before?) that I'll be working up a slightly more budget line for HT use that will likely include a center that could work with your current dimensions.

Finally, where are you located? If we can get measurements you could go completely custom. That's how the Khan series came to be.

Be very wary mixing designs from different designers and drivers. Sonic mismatch issues, and I don't recommend it.

I'm in the middle of "movers show up at 8 tomorrow" packing so may have more thoughts later.

C

[Thoth]

Thanks for the feedback! I’m (obviously) very new to this stuff so I have never had the chance to listen to any of your designs, but everything I read tells me that I really want to. Very impressive work. After my original post I realized that some focus and clarification are called for. Maybe this will help:

I guess the questions really boil down to “what would you gurus build into this space if it was yours?” Budget is somewhat flexible – I’d like to say $1,000 for the LCR components?? Of course the subs are already built (but could be changed based on expert advice) and the cabinetry will be part of the overall fireplace surround regardless.

It’s not really clear from the drawing, but the built-in will be about 30cm deep, so from an audio perspective I guess it is really an on-wall design. Don’t know how much that differs from in-wall, but just though I should point it out. It also allows front and/or side porting if called for.

I can definitely move the TV down. That is actually my preference since viewing would be more comfortable, but I was (perhaps incorrectly) assuming that the center would be better if aligned at seated ear level. The mantle shouldn’t be an issue either way since the face of the center could be built out flush with the front of it. We have near-total configuration latitude here as long as we stay within the general areas shown on the drawing.

Roger on not mixing designs – my further reading made that very clear. I want the LCR to blend as much as practical.

My inexperience and caution were steering me toward safe adaptations of proven designs, but I love the idea of something completely custom! Of course I would need LOTS of guidance, but I’m pretty handy with all things technical (Georgia Tech would be very disappointed in me otherwise – Go Jackets!) and have been around many blocks many times, so just point me in the right direction. As for measurements, I assume that you mean acoustical rather than physical. Are there any practical DIY options for me? My location is central Texas (west of Austin).

When we talk custom, I should also point out that the HT “room” is just part of an open-plan living-dining-kitchen-gaming area that is fairly large (~800 square feet) and L-shaped with an irregular ceiling profile, so that may be quite a challenge. I can work up a floor plan to post if it would help. I had actually been toying with adding some Polk in-ceiling DVC speakers in some spots to help with hearing the TV when folks are outside the “sweet spot”, and would love to hear thoughts on that. We do listen to music, but this will be 90+% home theater oriented.

Thanks again to for your interest and advice, and thanks in advance to anyone else who wants to chime in. I have to say that my expectations for this project were originally pretty modest, but now I am getting excited. If I can provide a quasi-interesting challenge, do something fun and original, and learn cool stuff in the process, it would be a blast!

Good luck with your move. My F-250 diesel pickup is available this week if you want to borrow it, but you have to pick it up (and return it eventually) here in Texas...

[Thoth]

Here's a floorplan to show what we are actually working with:

[5th element]

Zaph has his ZA5 designs that would probably work.

http://www.zaphaudio.com/ZA5/

Close to the bottom there are some in wall designs.

[Thoth]

Thanks Matt. The link was very helpful, and once again I learned a lot. Whenever you start something new it's always shocking to realize how much you don't know! Seems like the main takeaway from Zaph is that in-wall is always preferable to on wall. To quote directly, the in-wall "will have far better results than a "reduced baffle step" design in a rectangular enclosure placed up against the wall."

Well, damn :banghead:. I've already sold the spouse on having these really cool DIY speakers built into the new fireplace surround. She is really committed to the square columns, so I don't see any practical way to get a true in-wall infinite baffle configuration. Since some sort of compromise is inevitable here, which is the lesser of the evils - modifying the in-wall or the box design for on-wall use? I'm definitely up for at least semi-custom mods, especially with guidance from forum members like y'all.

BTW, love 5th Element and the Ruby Rhod handle. But the wife and I always come back to the "dangerous gun / nice hat" scene. Take it! I don't NEEEEEED it!!

[---k---]

Just remember, most people hear are perfectionists+ .

I agree that In-Wall is better than On-Wall. Measurements and my own listening confirm this. But that doesn't mean On-wall is always bad. I think a lot of casual listeners like my wife wouldn't notice the difference. So, evaluate how critical you're going to be and decide from there.

I think CJD's suggestion are great if you're going for the over the top theater. CJD's personal in-wall HT speakers are great. They match with his quad 15" IB sub well. (Just trying to put the level of crazy in perspective ) There are a couple of guys who use the Khanspire's on-wall. I've never heard anything bad from them about it, but they could just be being polite or not know the difference. If you're inclined to go that way, talk to Joey Butts. He's over at PE a lot. The In-Khan's will probably work really well in a partial in-wall / on-wall mounting. Same with the Khancenter.

If you just want something that will make you very happy, impress your friends, but not the best on the net; then maybe you don't need something so large. The Zaph in-wall kits would probably would quite well. My brother has the Ochocincos that I built for him in a room similar size and it can be pretty impressive. I'm guessing the Zaph kit has similar output capabilities. So, I wouldn't hesitate to recommend the Zaph kit from a loudness perspective. Having a pair of good subs will really help.

[Thoth]

Everything you said is spot on, Ryan, especially the last part about impressing my buddies while still being very happy with the quality. My wife and I are certainly not audio perfectionists like those typically found here, but we generally strive for the best quality we can reasonably have. Who better to ask for advice than the experts and perfectionists? Also, I am an engineer which automatically makes me say "there is always a right answer, damn it!" Anyway, I really appreciate your practical approach to my question.

I had previously read your write-up of the Khanspires, but this time I finally saw FAQ #9 talking specifically about on-wall suitability and CJD's crossover mod :duh:. So unless someone just screams "NO! Don't do it!" I think that's what I want to try. Talk about impressing the friends! Anyway, couple of additional questions that refer back to the sketch in my original post:

1. Since they would be installed above the sub rather than sitting on the floor, would there be a problem "inverting" them - putting the MTM section near the bottom and the the woofer enclosure volume at the top?

2. My gut tells me that I want to use the sealed design. Any benefit (or drawback) to that in this on-wall situation, other than the obvious size differences?

3. This means that I would probably want to also build the Khancenter, but it's size would necessitate moving the TV as low as possible, and placing the speaker above it - about 2 meters from the floor! Thoughts? If I go that way, should I plan to angle it down toward the seating area?

4. My current receiver is a Pioneer VSX-43. The specs say minimum 6 ohm guaranteed load, and I'm assuming there is no practical mod to the speaker design that would raise the impedance? Oh darn, guess that means a new receiver !

Thanks again! I am really looking forward to this project, and will continue to pick brains and post updates along the way!

Don

[---k---]

You're an Engineer. 8O Shocking! (Sarcasm. Lots of Engineers here.)

Crackyflipside built them and placed them on-wall. His thread was here: http://www.htguide.com/forum/showthr...re-build&pp=35 I don't remember hearing from him afterwards and looking at the thread here it seems to have died with them sounding great but measurement issues. IIRC he had a bigger thread on AVS (I don't hang out there anymore). Might have more info at avs. Maybe some foam on the sides walls will help reduce the bounce back?

1. Probably. I'm not sure how much of the bass response takes into account floor bounce that will increase the bass levels. Maybe if your ceiling is the floor? But then this messes up the tweeter height. Ideally, you want the tweeter height to be on level with your ears. There is some roll off above and below the tweeter. I'm sure CJD can give you some tolerances you want to be within.

Maybe you should consider building stadium seating to raise your sofa up and add a few rows for all those buddies you're trying to impress. Then you could add some bass shakers to the floor.

2. Yeah with good subs (I don't know of the Pinnicle brand you have) that you intend to always use, then I don't see a reason to go ported. Just my philosophy. If you're a music lover, some claim benefits to using a full range speaker and no subs. But, I think a well designed, well integrated subs would win in most cases. ... but with your subs being placed basically the same position as the speakers, maybe the room position argument goes out the window. Don't know. I just don't see what you'd gain with ported and subs vs. sealed and subs.

3. See my previous answer about the tweeter height. You're already screwing with ideal set-up, so sure why not place it above. Just want the face flush with the screen. I'll have to post a picture sometime with my latest center channel mod.

4. Nope. No change can magically make the speakers 8-ohm. You're probably okay with it. I don't know. People do it. Jamming at rock concert volumes with the Blue Man Group DVD to all 5 channels at the same time might get challenging. But most programming? Who knows. The internet is full of reports it working. I can only remember a few people saying they sent their gear into protection mode. But, they could be too embarrassed to post.
I would't get a new receiver. For whatever reason, there are very very few 8 ohm DIY designs. The drivers available to us just don't work well in 8 ohm designs.

I would add on a separate amp to your current. I run an Onkyo receiver with an Outlaw amp. Check out the Emotiva gear. Lots of positive reviews and good value. https://emotiva.com/ The XPA series would probably work out nicely.

[---k---]

Here's Joey's thread incase you didnt' find it:

http://www.htguide.com/forum/showthread.php?37330-Khanspire-s-Build-Thread

He has a couple more on PE with the surrounds and his new house build out. Probably worth checking out.

[Thoth]

Thanks Ryan. The photos and other info in the Joey's thread are going to be incredibly helpful. Anything else I should know before I wade in? Is the BOM on your site current? What about CJD's on-wall XO mods - anything new there? As soon as I actually get going I will start a new thread to document my screwups er... progress!

Love the stadium seating idea, but right now I have not just approval but downright enthusiasm from the wife - better not push my luck!

I'll take your advice and give the receiver a try. At least if I brick it I'll have to get a new one! Like the amp idea, but the VSX-43 doesn't have preamp outputs. Now I know why it was on clearance...

Yeah, I shoulda figured we had a bunch of engineers here. Everyone has probably seen this Dilbert clip, but thought I would post it again anyway just in case.

Don

[---k---]

I was joking about the stadium seating, but do give some thought to how you can get your ear level closer to the tweeter height of the mains.

We haven't changed anything. It has been so long, I can't say if all the parts numbers are the same. I'm sure the prices are way up. 8O
Just make sure you read through the three threads a couple times. There is so much in those threads that I've forgotten. It's been like 7 years since I built mine! 8O
It is also well worth the time to read and re-read the NatP and ModulaMT threads to get an understanding of how John builds things and lays out his crossovers. They were my reference.
I would suggest building the center channel first to get experience and then move to building the mains.

CJD can probably give the best input on changes for on-wall. I'm not sure if putting foam on the back wall on either side of the speakers would help.

I'm shocked that your receiver doesn't have pre-outs. but not really. That sucks.

[cjd]

I'm always slightly worried about potential disappointment when people wander from the path, but there it is. You would probably be OK flipping the Khanspire. Then again, I thought the Overkill project would be OK like that, and turns out it wasn't. If Ryan were a helpful sporting soul, he'd figure out how to mount a Khanspire on the wall in his garage and give it a measure. :P (I'm too busy unpacking to work on speakers! Too busy even to set up a bit more of a stereo so I can listen...) My gut says it will emphasize the slight midrange push built in (which helps make speech easy to understand at lower volume levels)

I've pushed 110dB in my old HT and am fairly sure the amplifier running out of juice is part of the problem, and with more clean power (I'm eyeing more Emotiva gear! XPA-3 and XPA-5 perhaps) that might almost be listenable for the few seconds it's not painful. As it is, it gets a bit harsh. And that's on the WMTW (tweeter was below the mid in my setup) and crossed to the subs at 60Hz. I suspect they would be more than adequate, with the only challenge being no center (unless you use an acoustically transparent screen like I do) with the same tweeter.

C

[Thoth]

Thanks again guys. I did re-read through all the old threads much more carefully, and realized that the answers to many of my dumb questions were in there all along. ops: Sorry...

Good advice about building the center first for practice - may try to order parts for that today! Assuming Ryan is not going to be able to do the garage testing per CJD's request (c'mon... it would be way more fun than silly stuff like sleeping or going to work!), I'm thinking about doing the mains like Phish, with the drivers centered. Turns out to be a pretty good compromise in my situation between ear alignment and center of screen for the tweeters. Thoughts? Did he do a build thread somewhere I could check out? I did a quick search but could only find the one mention of them in the original Khanspire thread.

The Emotiva gear does look sweet, but probably going to try and get through with my poor old Pio until I recover from building the speakers. If I understand y'all correctly, I will probably be OK as long as I go easy on it, right?

Thanks again for your help, guys. I'm really itchin' to start making sawdust!

Don

PS: Thanks for the disclaimer CJD, but please don't be concerned at all about potential disappointment on my part. Beside the fact that I would probably be thrilled and astounded by things that you would find disappointing, I am in this as much for the fun, learning experience, and overall WOW factor as anything else. Sonic perfection is a very cool and worthwhile goal, but certainly not necessary here. After learning from this experience I may want to try again, but that'll just mean more fun!

[---k---]

If CJD would show up with all his measurement gear, we might be able to make something happen. But, I don't see any time in the near future. Maybe after we see a center channel built and constructed we'll be inspired.

When you plan out the center, remember there is some options in the depth and width. IIRC I built it deeper than really needed.

Also, when planning out all your trim around the speakers, I'm thinking you'll want as few protrusions as possible to limit all the reflections. There probably is a photo of my center channel under my TV. I thought it sounded real good like that. I thought the stand was open enough. But, speech was sometimes difficult to understand - especially British TV which I'm not as used to and the accents made it difficult. My center now has plywood on all sides to make it like an inwall. It looks like crap, but improved the speech slightly, which was just enough. I'm preferring it. Too many reflections before from the cavity.