The speaker project (dialup warning)

TRADERXFAN · « **Reply #21 on:** 21 Sep 2009, 02:01 am »

Great stuff here Josh! Keep it coming... Can't wait to see how it turns out.

I feel you on the pain of the finishing. What do you plan to do, paint?
I always do at least 2 coats of the glazing putty. And don't forget to cover the roundover with it. I made that mistake...

-Tony

JoshK · « **Reply #22 on:** 21 Sep 2009, 07:18 pm »

I am planning to veneer the bass bins and paint the MT. Maybe I'll veneer the sides of the MT, maybe not, we'll see.

face · « **Reply #23 on:** 22 Sep 2009, 01:28 am »

Looking good so far.

JoshK · « **Reply #24 on:** 22 Sep 2009, 01:51 pm »

thanks. I am attempting to make this thread sort of a "build thread" just in case it inspires anyone else. However, I am not organized enough to make it a true document of my build process.

I have to thank for forum members for pointing out the single tube glazing putty. It definitely works a lot better than the two part stuff for small imperfections.

Hebrew Hammer · « **Reply #25 on:** 22 Sep 2009, 03:43 pm »

looking good bud.. I tend to use duraglass which is more autobody stuff for filling holes and dips.. IMO, going the autobody way seem to last longer as the products are made to handle extreme temperature and environment issues.

have you veneered before? it's not hard at all... I did the Elise set with wood glue, non backed veneer, an old t shirt and a clothes iron...

JoshK · « **Reply #26 on:** 22 Sep 2009, 04:07 pm »

I've done some veneering, but not on a completed project (well except for one disaster, I like to call a learning experience). I used the iron-on method and it works really well. I am definitely doing the same this time. I just need to do a little bondo'ing of a couple of of hte corners as they weren't perfect in a couple areas. After that I'll veneer.

Bob in St. Louis · « **Reply #27 on:** 22 Sep 2009, 05:03 pm »

Quote from: JoshK on 22 Sep 2009, 04:07 pm

I just need to do a little bondo'ing of a couple of of hte corners as they weren't perfect in a couple areas.

Grab yourself a tube of Bondo "Glazing and Spot Putty" instead of the body filler.
I've used both, and for smaller fills, the Spot Putty is MUCH easier. The stuff I got isn't a two part, so there's no mixing. Also, the working time is much longer. Another advantage, is the Spot Filler sands "equalier" to MDF than the diamond hard body filler.

Bob

p.s. Sorry to make up words, but it sounded so right at the time.

JoshK · « **Reply #28 on:** 22 Sep 2009, 05:45 pm »

Thanks Bob. As I mention, I was recently made aware of the 1 part stuff and it is definitely a lot better to work with for fine details. In the case I was referring to though I actually have to build up a seam a little, as my joint wasn't perfect. On most all seams I left a little overhang and used a flush trim bit to true it up, but I did goof on at least one partial seam.

If it were just a little bit larger of a mistake I'd rabbit it out and epoxy in another piece on that seam, but I don't think its worth that much effort, I'll just smooth it over with bondo.

Bob in St. Louis · « **Reply #29 on:** 22 Sep 2009, 05:59 pm »

Quote from: JoshK on 22 Sep 2009, 05:45 pm

I'll just smooth it over with bondo.

Famous last words.

Been there, done that Brother. (sorry, that's a private joke between me, myself, and I)
What you've got going for you is that the final "coat" will be veneer as opposed to paint. I've had a hard time keeping the seams of laminated MDF layers from "popping through". Even after multiple coats of fiberglass resin.

But the veneer will hide all but the nastiest of mistakes, you'll be fine.

Great thread, thanks for the pictures. Carry on soldier!
Bob

TRADERXFAN · « **Reply #30 on:** 22 Sep 2009, 06:14 pm »

I had pretty good success using minwax wood filler on any true seams/ gaps and sand.

Then to make that texture smooth as glass, use the single tube stuff over that and sand with 320 400 grit... and then shellac and re-sand.

-Tony

JoshK · « **Reply #31 on:** 22 Sep 2009, 06:17 pm »

Quote from: TRADERXFAN on 22 Sep 2009, 06:14 pm

I had pretty good success using minwax wood filler on any true seams/ gaps.

Then to make that texture smooth as glass, use the single tube stuff over that and sand with 320 400 grit... and then shellac and re-sand.

-Tony

Good idea. I didn't think about the wood filler. That would be too obvious.

JoshK · « **Reply #32 on:** 16 Oct 2009, 01:28 pm »

Wood filler is your friend. Or its my friend.

No pictures to show but I got the sides, top and bottom glued on the Blitzen (MT top). I cut the veneer and laid down my first piece on the Donner (bass bin) **. Its basically all finishing work now.

For the Blitzen, I decided on U baffles. I'll be stuffing them to yield a cardiod response in the lower end. This will hopefully transition the power response slowly and smoothly between the narrow CD response of the waveguide down to the omnipolar response of the Donner.

I've been taking my dear sweet time with these speakers. I am in no hurry as I have a pair of speakers set up already for listening to music. I think this is key, as I am enjoying this build process even more than some of the eletronic projects I've done. I'm learning a lot along the way.

I've had my share of mishaps and snaffoos, but if you are patient, generally they are easy to rectify. I think woodworking is about confidence, patience and measuring numerous times.

** I picked up the Bosch Colt variable speed palm router off a suggestion on another forum. I had a 10% off coupon for the orange box and they had the router matching the best price I could find online, so I jumped. Its a sweet little toy. Works very nicely to trim the veneer flush. Regular routers work fine but aren't as easy to handle and watch what you are doing.

JoshK · « **Reply #33 on:** 27 Oct 2009, 01:07 pm »

Well all this talk of horns got me a little excited (horny?). I had always intended to experiment with my upcoming speaker project, having made it modular on purpose.

I ordered a pair of Eighteen Sounds ND1460As yesterday and I am still waiting on a shipping quote for a pair of DDS SW 1.4-90 LF. Ordering from Assistance Audio takes some patience. Jack is nice in his emails but responses are slow and hard to come by.

The idea is to try out how my this waveguide/CD combo mates up with my bins in a 2 way design. Its true that response falls off pretty quick beyond say 14k, but then the bins start dropping off below 50hz too. I firmly believe loss at one extreme isn't as noticeable if it is mated with loss at the other in balance. I think this is a lot to do with folks like single drivers.

Crossover can be in the 500-600hz range, if one can take these measurements seriously. What is not to like about having no crossover in the critical hearing region?

There is a thread about these waveguides, where I learned of them. They don't look all that different from the profile Paul used in the Octagon project, but they are only 24", not 30".
http://www.diyaudio.com/forums/multi-way/149085-testing-big-waveguide.html

By the way, I ordered my ND1460As through Paul. He doesn't really advertise it but he is an 18Sounds dealer and he is a lot more diligent than many dealers. I prefer to support my fellow audiophile..

JDUBS · « **Reply #34 on:** 28 Oct 2009, 12:48 am »

Josh, very interesting thread on the DDS SW 1.4-90 LF! Will be curious to hear what you think of them vs. your Geddes waveguides.

I need to ask Earl about the foam plugs. I didn't know he sold them by themselves. I should look into getting them for my Unitys (if they'll fit).

-Jim

JoshK · « **Reply #35 on:** 28 Oct 2009, 03:15 pm »

I still want to hear your Unities. Your welcome to come hear my setup when it gets rolling.

You have a DEQX as well, so I think we have many things in common in our systems.

nullspace · « **Reply #36 on:** 29 Oct 2009, 03:37 pm »

Josh,

I think the measurements you linked to had some EQ applied. PaulW has unsmoothed measurements of your driver on his horn here: Large midrange for OB??? Scott G ?, which incidentally look quite a bit like the 18sound published curves. The 18sound published impedence curve also looks very much like what PaulW has posted. Hulkss posted unsmoothed/uneq'd responses for the DDS horn, but they are with a Radian driver: Testing The BIG Waveguide.

In any case, I don't see how that driver on that horn will sound anything less than amazing. You've said that you're going to start with an active crossover, but from what I've seen the 18sound driver should be very amenable to a passive crossover. Outside of the break-up @15kHz, I don't see anything squirrely at all.

Regards,
John

JoshK · « **Reply #37 on:** 29 Oct 2009, 04:59 pm »

Hi Jon,

Thanks for your comments. I am pretty excited about playing with these. I think, in terms of my own learning curve, that this is quite possibly an easier nut to crack for starters then the three way will be. This, hopefully will let me start running a bit sooner.

The graphs do look quite good, great even. Assistance Audio came back and said the two waveguides they thought they had in stock aren't in stock, so they have to order them from DDS. So a minor setback in terms of time but that is ok, I am going to probably take some time to finish the bins.

I like the idea of trying out passive crossovers, but active will likely be easier to pull off at first. But I do think it will be quite possible to do passive, it just means accepting the sensitivity of the bins (~95db/w) minus any baffle step compensation. However, the world of amp solutions open up a bit. Still I like the DEQX as a DAC/preamp, so why not use its capabilities?

The one thing about Paul's measurements that I didn't quite understand is the corner at which SPL starts to fall seems a bit high for such a large waveguide. Since it is a mound, one can probably work with it to extend the lower cutoff for home use of these drivers.

I'd like to cross directly to the TD15Xs for this setup. They have a mild surround resonance @500hz but otherwise extend well up to 1khz. I think this should make a nice duo.

Hebrew Hammer · « **Reply #38 on:** 29 Oct 2009, 05:22 pm »

less talky more pics

nullspace · « **Reply #39 on:** 29 Oct 2009, 05:24 pm »

I don't have any experience with 1.4" or 2" drivers, but it looks to me that at some point it doesn't matter how big the waveguide is -- as you approach the driver's resonance the freq. response is going to roll-off. Also, Paul said he used a short gate in order to cut out room reflections; I'd like to know how short is 'short' before making any strong statements. To me, it looks pretty short, 3ms or so, but I could very well be wrong.

I wouldn't give 'the mound' a second thought. I think you generally see something similar in every axisymmetric horn/waveguide, and you get rid of it with a notch filter or finagling with the crossover -- I've seen it handled both ways.

Regards,
John