Next Project: floorstanders = Zaph Audio ZDT 3.5 build

[oneplustwo]

Now that I've finished my SR71's, I'm ready for the next project. Actually, I wasn't planning on doing an upgrade so quickly, but I can't figure out a way to set them up in my room with the kids and the tv stand so I'm thinking this is a good excuse to do a set of floorstanders.

Don't want to spend a ton of $$ but I was thinking the zaph ZRT or the ZDT3.5. ZRT has crossovers built and is a simpler build. ZDT is cheaper and 3.5 way which is cool. Thoughts?

[numberoneoppa]

What's your budget? I'm pretty happy with the North Seas as a 2-way tower, but I'm also very tempted to build a something like the Khanspires, which are a bit more expensive, but probably a bit more awesome. The Zaph ZA5 kits are also kinda tempting.

So many awesome speakers, so little time!

[oneplustwo]

What's your budget? I'm pretty happy with the North Seas as a 2-way tower, but I'm also very tempted to build a something like the Khanspires, which are a bit more expensive, but probably a bit more awesome. The Zaph ZA5 kits are also kinda tempting.

So many awesome speakers, so little time!

I feel the same way! Too bad speakers are so big or I would be tempted to build a bunch more just to compare for myself.

As for budget, I was thinking between $500 - $1000 for a pair, drivers and crossover components only. The ZRT is on the high end, the ZDT on the low end. I'm tempted to go ZRT with the quality of the drivers, simplicity of build, and thinking that I would be happy with them for a long long time. However, the ZDT's seem to perform very well also and may have some benefits being a 3.5 way system. I will say that my room isn't that big (I'll be about 2-2.5m away from the speakers) so I'm not sure that's enough distance for the 3.5 way to work well. The ZA5 MMTMM setup seems like an option as well, but it appears that I would be able to get more lower freq bass response from the larger drivers of the ZDT and ZRT designs. (I would like to avoid getting a sub as most of my serious listening is music.)

*sigh* another option of course is to just figure out a way to use my SR71's in a kid proof manner but where's the fun in that! Plus, I kinda already have plans for them in my office downstairs.

[numberoneoppa]

Though choice. The ZRT is expensive, though, which means you might not want to build anything else for a while. For me, building is half the fun, so I'd rather build a few 3-400 dollar kits than one 1000 dollar kit.

The ZRT is probably one of the best sounding 2-way speakers out there. However, I question its ability to play low notes loudly with only 1 7" woofer (the ZRT 2.5 is another $tory).

[oneplustwo]

That's a good point... my only issue is what to do with all these speakers. Do you give them away? Put them in different rooms? Storage? Sell them?

[numberoneoppa]

Put them in different rooms or sell them at cost to friends. Depends on how much cash you have to throw around. I'm a college student so I'm trying to get friends to commission me to build speakers for them at cost, just to improve my experience and get the fun of building them.

Tough decision, isn't it?

[evilskillit]

I'm getting ready to hit a point where I'm going to have more speakers than I have stereos. I'm going to offer them to friends for cost if anybody wants em, and try putting em in craigslist or trying consignment shops if the local high-fi place still does consignment.

As for your next design if your whole reason for not using the SR-71 is because you can't keep the kids off of em do you really want to build something nicer and more expensive? You might consider the Tritrix, if the kids destroy any individual driver its going to cost under $20 to replace, heck you could buy two extra tweeters and two extra woofers for under $80. Heh. Otherwise if you want something bigger and better you might also look at the Zaph Waveguide TMM which I'm currently working on, or John's new Modula MK2 TMM. That thing should be incredible.

Another thing to consider would be a design which uses the Dayton RS28F or RS28A tweeter as those have a built in mesh grid which keeps little fingers out of the tweeter, so no chance for damage. The Natalie P can be built with those tweeters, as can the Dayton RS-TMWWs and probably several other designs I'm forgetting. Then Dayton Reference woofers pair up well with those and are pretty hard for little kids to damage short of tearing the surround or denting the cone. Even if they do manage, replacing those drivers aren't terribly expensive.

The Zaph ZDT3.5 meets most of the requirements that I've mentioned except it uses a tweeter with an exposed dome that has to be press fitted, so if probing little fingers find it you'll have to go in from the back to push it out and replace it, also I think availability is an issue, not sure. Either way good luck with picking your next design and congrats on your finished SR-71.

[oneplustwo]

Thanks evilskillit. I may wait a bit and finish my amp up first and think about some super beefy speaker stands for the SR71's. The ZDT3.5 may be in my future though as it is relatively inexpensive and accomplishes a lot of what I would want. At least until the kids are older.

[cjd]

FWIW I had a pretty badly damaged RS270 (still hve it, in fact) and it added some extra bobbles to frequency response and impedance once I sorta straightened it out, but overall it was amazingly little change. I still replaced it, but...

Then again, as a kid I knew not to push on tweeters, and exactly how to push on woofers without damaging them... my dad didn't like grills on his speakers, see...

[oneplustwo]

Good to know cjd. I think I'll be ok with them in my office. The more I think about it, the less I think speaker stands are going to be safe enough actually. I still want to put some more thought into it, but ZDT3.5's may be in my future.

[evilskillit]

The Waveguide TMMs I'm building have a pretty large empty cavity in the bottom. I keep thinking of filling part of it with sand or something to give them a lower center of gravity, keep them less tippy and more coupled to the floor. Then again the whole reason I'm using birch instead of MDF is I'm tired of the weight, so that would be sort of counter intuitive.

[oneplustwo]

I was considering how to make whatever I end up with more stable as well. Sand seems kinda messy. I thought about getting some scrap pieces of steel (maybe stainless) from the local metal works shop and bolting it to the bottom somewhere. That way, I can remove them and move the pieces individually vs. carrying one heavy unit.

Just one more detail to think about! Maybe I'll try to match the SR71 style with a mix of ply and mahogany. Or maybe different species but the same construction. Hmm...

[oneplustwo]

Here's yet another option for your consideration. As you probably know by now, safety is really my number 1 priority with the kiddies running around. As such, I'm thinking that keeping the speakers closer to the TV is probably better first in order to reduce the overall size of the layout and therefore reduce the risk of someone running into the speaker and second, to reduce the chance of them running or playing hide and seek between the speaker and the TV itself. So perhaps the ZA5.3c MTM center channel system would be best (built as towers.) This would also be close to half the price of the ZDT 3.5 system although some of that might be spent on a sub woofer later on if I feel the bass reach of the ZA5 kit is lacking. Speaking of which... that leads me to another question.

What's the best way to configure a plate amp for a basic stereo system? My understanding is that I could go from my power amp to the plate amp to the speakers and the plate amp would effectively "remove" the lower frequencies depending on where you set the crossover knob and reproduce those frequencies itself. My question is, does the power/signal to the speakers get degraded in any way due to the intercept from the plate amp? I know there are receivers with dedicate bass signals and built in crossovers, but my system will be a DIY DAC to a DIY pre-amp to a DIY power amp. 2 channel only and no bells and whistles.

If integrating a sub with what I have planned is going to be too awkward, I'd probably just go ahead and build the ZDT 3.5's. That might be the better direction in the end anyway all things considered. Like how I just talked my way in a circle?

Sorry if this is a noob question but I thought it worth asking given what seems to me at least to be a unique set of circumstances.

[evilskillit]

You don't want to use the high pass pass through feature of the plate amp as it doesn't work very well and sounds nasty. Your best bet is either running your mains full range and dialing the sub in by ear where they roll off. Or since you're a big DIY guy you could roll your own DIY active crossover to highpass your mains. Shouldn't be too difficult or cost too much, but thats up to you. That is my recommendation. Well built DIY subs are a beautiful thing, especially for watching movies. I wouldn't pass on one unless finances are a problem, or you just don't like bass.

The other option would be buy or build an amp or preamp with an active crossover built in, or buy an active crossover. Units from Behringer or Reckhorn can be had for well under $200.

Another nice feature of high passing your mains is, especially with smaller mains, that they can play much louder without distortion. My Microbes sounded great before, but after highpassing at 75-80hz with a sub they really started sounding a lot more full and energetic.

[oneplustwo]

Ok, I've talked myself into the ZDT's. Thanks for letting me think through it and providing your thoughts. Looks like the enclosure has 2 boxes with the crossover in the bottom. How do I get the wires from the crossover into the two boxes? Ok to just drill holes or do they need to be further sealed with caulk or something?

[numberoneoppa]

nevermind~

[evilskillit]

Ok, I've talked myself into the ZDT's. Thanks for letting me think through it and providing your thoughts. Looks like the enclosure has 2 boxes with the crossover in the bottom. How do I get the wires from the crossover into the two boxes? Ok to just drill holes or do they need to be further sealed with caulk or something?

Yeah just drill a hole, but yeah just to make sure you don't end up with an odd whistle or something you'd want to fill the hole with some sort of caulk of silicon after you run the wires. Make sure to keep the cabinets open and give that junk a day or three to offgas as the fumes can tear up your speakers and crossover components.

[oneplustwo]

Is there a document out there that speaks to best practice crossover building? The SR71 crossover came pre built so this will be my first one. I saw some recommendations on inductor relative placement but didn't know if there were other things to consider or tips/tricks that would be helpful for a first time builder. Maybe even some pictures of "gold standard" crossovers?

[evilskillit]

There is a thread going on right now on the partsexpress techtalk forum about building crossover boards. Honestly from what I know the best way to do it is just give the leads from one component to the next a twist, solder em and clip off any excess. Its a better connection than terminal strips and its less likely to introduce any extra inductance into the path than any other options. Its simpler and cheaper than PCB or bread board so you save a few pennies and are less likely to make silly mistakes, it creates the shortest distance between two components.

There are some other things to know, like don't put inductors close to each other and if you do orient them differently. I'm sure plenty of other people can chime in with more useful info. This is my advice, unless the crossovers are visibly displayed looks don't count for anything, just keep it simple and sweet, and try not to make mistakes that deviate from the design or put components in the wrong places.

[oneplustwo]

Ok... got my kit from parts express and am ready to plan details of the build. i was thinking about basically replicating my SR71 build except my wife would like the front to be black. I was thinking about just sanding, priming, and painting. Any suggestions about what paint? I was thinking flat black but I'm having trouble visualizing how that would look in this application. I'm looking for something fairly simple but clean looking.

[bbcmp1979]

I did a semigloss on my Natalie P build. Not too reflective at all.

[oneplustwo]

looks good! what was your process?

[bbcmp1979]

pretty simple actually, sand, primer, sand, primer, sand, and 3 coats of paint. I haven't sand the top coat of paint yet. I don't plan to actually.

[oneplustwo]

Is there such a thing as a textured paint that has a granular surface? Not like the hammered finishes you sometimes see in the auto stores and hardware stores. More like almost a sandpapery kind of finish. The only example I can think of is this kitchenaid mixer I once saw that had this sort of rough, grippy texture. Does that make sense?

[numberoneoppa]

Is there such a thing as a textured paint that has a granular surface? Not like the hammered finishes you sometimes see in the auto stores and hardware stores. More like almost a sandpapery kind of finish. The only example I can think of is this kitchenaid mixer I once saw that had this sort of rough, grippy texture. Does that make sense?

It exists, there are many kinds of textured paint. It's usually used on imperfect surfaces like fiberglass cabins of boats and aircrafts. You might also look into pickup truck bed paint.

[evilskillit]

Like how granular. Theres always faux marble finish.

Btw, I used flat black spray paint with a semi-gloss poly clear coat on my Microbes, they look pretty nondescript, which is what I was going for. Ignore the imperfections in the finish, I was impatient and lacked tools and didn't sand nearly enough.

Also earlier you asked about building crossovers and I thew my hat in for info. Here is how I built mine.

[HeatMiser]

I've found it's possible to get a wide range of textured finishes from common Rustoleum "hammered finish" rattle cans if you want to experiment with something inexpensive and readily available. More/lighter coats with the can held a greater distance from the work approaches the kind of finish I think you're looking for, with heavier coats creating noticeable "blobs" for the hammered look.

You'll need some kind of protective clear coat with this stuff; I suggest something that brushes or rolls on as I've found spraying over this type of "powder" finish (at least with the spray clearcoat I tried) tends to trap air in the textured paint for an unattractive milky result.

I'm sure there are many ways to skin this particular cat but it might be worth trying out on some scrap for the price of a couple cans you can grab at any Home Depot. :T

[oneplustwo]

Pickup truck bed paint might be good! Anyone try this for speakers? http://www.rustoleum.com/CBGProduct.asp?pid=367

[BobEllis]

Everything old is new again! A couple of years ago, it seemed that almost everyone not veneering went with truck bed liner.

I've found textured finishes tend to collect dust after a couple years that can be a pain to clean. Your home may have less dust kicked up.

[oneplustwo]

Hmm... a three year old and two infants = lots of dust and other yucky stuff. But it would only be the front panel and top that would be "truck bed linered." The rest is birch ply that I'm considering danish oiling or staining. So that helps a little. I see your point though. Maybe a flat black would be the better way to go. I'm lazy though and like the simplicity of the truck bed liner. Might be worth a try just for my own personal edification.

[dmalphur]

The rustoleum "textured" paint gives impressive results; you can vary the texture by how many coats you apply.

I would start by sealing the edges of the MDF with sanding sealer, applying a flat black base coat, then the textured paint to taste. A misted coat (from approx. 16" away) of clear over the textured finish makes it easier to wipe down when it gets dusty. You can vary the glossiness of the final product by how thick you put the clear on, just be careful, too much or holding the can too close and you will leave shiny spots.

-David

[evilskillit]

I was trying to make my whole cabinets out of birch ply, but the front baffles got ruined due to router bit / junk plywood. I decided to go ahead and just make my front baffles out of MDF so as not to end up having to make a 3rd pair. So I'm going to be going with the birch ply cabinets with oil and rustoleum textured black for the baffles. We're building 2 Zaph designs and finishing them in a similar style. We could exchange boxes if we cared to, heh. Except I'm gluing my front baffle on. Anyways good luck. Post pics, it'll be funny to see how similar they end up to my WG TMM build.

[oneplustwo]

Will do. I made some cuts this weekend. Will glue up the perimeter pieces next and cut the holes for the baffles. I haven't decided on the removeable baffle thing yet. I like the cleaner look of gluing it in. And it seems simpler to me as well. Plus, I don't expect I'll be repurposing the cabinet. It's not like I build THAT many speakers like Zaph does.

[evilskillit]

Yeah, I did want a removable panel in case I needed to fix stuff after the fact. Especially so I could mess with stuffing if need be. But I don't like screws sticking out of the front baffle so I went with a removable back. Which to me makes a lot more sense, as long as you don't want to repurpose a cabinet with different drivers in the future.

Here is a gallery link to my build, which is apparently the same cabinet. I'm no expert woodwork, anybody can probably do better, but you can at least see how mine came together if you want.

My Waveguide TMM Build

Things worth noting. Installing the damping was the most annoying part of all. Drill the holes in the divider panels to run your wires ahead of time before assembly, its easier.

[oneplustwo]

Looking good! Do you find it better to build from side to side? I did my SR71's from the outside in so to speak. But they were much smaller and only required a couple braces. Also, how are you attaching the rear? The same as you would have attached a removeable front baffle?

One thing I'll probably do for sure this time around is install the foam damping earlier on. Maybe even before gluing anything together. Trying to stuff contact cemented foam through the woofer hole was not much fun last time around.

[evilskillit]

Hah, yeah if you look at my BR1-S kit you can see I had to shove the foam though the woofer hole. I was using hot glue too. I got a few burns for my trouble.

I'm putting gasket tape all around the back to make for a good air tight seal with no rattles. Then I'm just going to countersink some wood screws. I put that frame rail around the back so wood screws should sink into it and hold just fine. I was going to use t-nuts and machine screws but it'll be more expensive, more work and I'll have to fiddle with shoving them inbetween my already installed insulation. That seems like too much work.

As for how I build? I haven't thought of a bunch of different ways to do it. I generally start at one corner, and go in one direction from there till most of its done. Then I start putting other sides on. In the case of these guys I glued the bottom to the side, then worked my way up till the top was on. Then slap on the other side, then fronts and backs. I guess you might want to do it differently if you were having different baffles overlap.

[oneplustwo]

Tweeter hole?

Hey folks,

Zaph recommends a 1 7/16" forstner bit to make the tweeter hole but I know some of you have done it with a 1 3/8" spade or other bit. I have a 1 3/8" forstner bit and will probably use that with some careful sanding to make it work. Any additional tips or watchouts? I'll get some pics up of my progress. Basically, it's the sides, insides, and top so far. I'm going to try to get the front and rear baffles done this weekend and get the crossovers built as well.

EDIT: not exciting pics



Also, here's the baffle of the ZA5.3 center channel I'm building for a friend.

[oneplustwo]

Well, I got the ply sides treated with some pre-stain and danish oil. Looks pretty nice I think. Unfortunately, during one of my recesses for the MDF front panel, I screwed up and made a good size divot where there shouldn't be one. Is there a good way to repair it? I was thinking either drywall spackle or bondo.

[evilskillit]

Bondo works great.

Pics look good, nice damping. I couldn't afford/justify the foam so I used insluation instead.

[numberoneoppa]

Bondo works great, much better than spackle in my experience!

[oneplustwo]

Bondo works great.

Pics look good, nice damping. I couldn't afford/justify the foam so I used insluation instead.

Thanks. I actually bought the foam from madisound. It's not as fancy but is much cheaper than the stuff from parts express.

Guess I need to make a trip to the auto parts store for some bondo. Grr...

[evilskillit]

They sell it at Home Depot and Walmart too. The only thing that sucks is you have to buy at least a quart or two, which you'll never use, and its not cheap, like $8 or $16 or something. But compared to wood puddy or sheetrock compound it's well worth it. The whole thing will probably rot to dust before that bondo patch fails.

[oneplustwo]

Ok... couple new questions for your enjoyment:

1. I was thinking about using the textured rustoleum to cover up some of the tearout on the ply wood at the top where it meets the MDF piece. Basically, I'd just tape off the plywood about 0.5" below the interface and shoot it with the stuff. Question is, should I do that with the front and rear baffles as well? I was originally going to spray them before gluing them down. That seems like the better way to go.

2. I have a class A stereo amp that will feed these when listening to music. I also have a 5.1 AV receiver that I would use for movies. Is it ok to wire the outputs of both receivers to the speakers at the same time? (Obviously, I wouldn't turn one on while the other is on.)

3. I'm also considering a sealed sub for HT use. Any recos on a DIY design? I was about to pull the trigger on an IB but didn't consider the WAF until the end. I'm not a big bass head but would like accurate bass. Might wait until the ZDT's are done and I can get a first hand look at how it handles the bass in movies. But it's always fun to research.

[ThomasW]

Bondo or a similar product is available in 1 pint containers at most auto supply stores

Is it ok to wire the outputs of both receivers to the speakers at the same time?

Absolutely NOT, you need a special buffered switch to do this otherwise, .... BOOM!! 8O

[oneplustwo]

Thanks Thomas. Would a DPDT switch work? As long as I got one sized right, it seems like that could be an easy solution. Otherwise, I guess it wouldn't kill me to plug and unplug the speakers every so often.