'Singularity' Build Log

[technodanvan]

Well I can't just let Steve have all the fun! I built an Amp Camp Amp a while back along with the B1 preamp. Given the gain on the B1 I can get usable volume out of several sets of small TM bookshelf speakers, but I wanted something with a bit more oomph in the bass department. It's kind of hard to get that out of < 10 watts coupled with small small speakers, so I figured I'd try out a somewhat high-efficiency speaker in a big box and see what I can get. Lo and behold, Curt already did that several years ago using the Dayton Audio PS220-8.

https://www.parts-express.com/Dayton-Audio-PS220-8-8-Point-Source-Full-Range-Neo-Driver-295-346



http://speakerdesignworks.com/Singularity_1.html



The total cost of the project isn't terribly expensive thanks to the reasonable price of the driver compared to competing offerings from Tang Band. It also gave me a great excuse to order some more wood from the local lumberyard; shipping is the same regardless of quantity, so I stocked up on more wood than I (currently) have projects. This one should go together pretty quickly overall, though I suspect painting the finished project will prove to be problematic since it'll need to be rattle cans.







I have the boxes gluing up right now and need to get some bags of salt to perform the next steps...

[JonMarsh]

Fast progress! keep it up, Danny!

:T

[technodanvan]

Minor progress continues. Ports installed (4" ID PVC x ~3") with Goop and backs have been adhered to the sides.





Debating whether I want to paint the cabinets before adhering the baffles or after. I see benefits and potential downsides to both methodologies. No rush on that decision though, I've got several more steps (and a vacation) before my hand is forced.

This is the first time I just left the braces all rough cut instead of sanding them smooth and rounding them over. Perhaps coincidentally, I've also been getting more splinters on this project. Maybe on the next project I'll take the extra time to clean things up...

Cabinets are big, bigger than my mains. Maybe should have thought about that since I don't have a permanent place for the ACA/B1 combo. Ah well, I'm sure I can cram them into my office if nothing else. Really looking forward to trying some classic rock on these.

[JonMarsh]

Just a few miscellaneous thoughts of no particular importance after having my morning coffee and reviewing the driver specs and the original design page... (you know the old saying about opinions...)

• This, from the description of the Dayton full range driver, drew a chuckle...: Solid bass performance, thanks to usefully high excursion capability (4.8 mm Xmax)
• from the Kippel data, I would describe the "linear" portion of the Xmax as +/- 2.5mm, based on criteria I use these days. But depending on the usage case, that may not be any problem.
• Considering the posted 2pi response from Dayton, and the higher frequency irregularities, I expected to see a bit more in the contour network than a basic RC impedance zobel and baffle step comp. OTOH, Kurt's published response seems to have taken care of the broad outlines, perhaps due to the series R interacting with the driver impedance in the upper range.
• I'm an "old school" transmission line designer (back in the 70's!) and did a 10" three way back then that was genuinely flat to a skosh below 30Hz; I haven't been all that fond of some of the MLTL concepts, because for me, a big stuffed box with a short port is not a true transmission line system... but the proof is in the pudding! But Kurt doesn't provide any in room or NF measurements... leaving the whole thing open to speculation.
• Can you do more complete impedance measurements and near field driver and port output checks, to low frequencies? That would be interesting...

[JonMarsh]

One more note, because of Hoffman's Iron law, the cabinet volume for this design is close to that of the bass cabinet of the Isiris! And about what I anticipate for an Isiris Mini... of course, this only needs a few watts, something like the Pass Class A design I bought in kit form ages ago and haven't had time to build!

And let's not forget the baffle step compensation- when you factor that in, and don't build this into a wall, then the real world sensitivity is more like 86-87 dB. Which is not at all shabby... but should be factored in to expectations.

[technodanvan]

I can certainly run an impedance sweep once assembled, and can try my hand at nearfield measurements as well...

Caught that line about the xmax as well, certainly raised an eyebrow. I suspect your little Pass kit is the same (or at least very similar) to that which I'm working with.

[Mikerodrig27]

JonMarsh, which Firstwatt clone are do you have waiting for you? I built the F6 and am thrilled with it.

[technodanvan]

Following Steve's lead, I decided to skin these with 1/8" hardboard prior to painting. I think I'm also going to attach the baffles before painting...unsure I'll do a 'separation strip', though it would look good with a dark wood. Something I'll continue to think about as I wrap up the hardboard.

[technodanvan]

Well I'm back from vacation and back at it. Wrapped up the skinning today by doing the top of each speaker - I think I'll pass on doing the bottom since I won't be painting that anyway.



Decided to try out one combination I thought of for a separation strip between the baffle and cabinet. Padauk is pretty striking, but I think it may look good since there is a bit of orange on the driver's phase plug. That said, I decided to put together a mock up sample to stain and see how it'll look once finished.



The other half of that is trying out the paint I initially selected. Yes, I think I'll be painting the cabinets dark green, with a 'natural' ply finish for the baffles and a (tentative) separation strip of padauk. I figure a fullrange speaker is kind of a goofy project for me to do, so why not mix up the paint job a bit too?





Speaking of the baffles, I hadn't made them yet. I've got the first one gluing up now.



Question for Steve Manning (or anyone else really): For the separation strip, I was considering taking an 1/8" rabbet about 1/4" deep out of both the cabinet and the baffle, for a total of 1/4" the padauk would slide into. Is this a better method than just taking a 1/4" out of either the baffle or the cabinet? Am I just creating more work for myself? If it makes any difference, the plan is to adhere the baffle after the rabbet(s) is(are) made, tape up the baffle (and gap as best I can) and paint the cabinets. Once painting is complete, tape up the cabinets along the edge of the gap, glue in the padauk, then sand it down to level with the baffle and finish with tung oil (or similar).

[Steve Manning]

Hey Danny ..... for what it's worth, I took the whole 1/4" out of the cabinets then glued in the trim. Did a rough flush trim and then glued on the baffles.

[technodanvan]

Thanks Steve, that's really helpful. I may take the same approach.

[Efalegalo]

Danny/Steve,

Quick question: when adding 1/8" hardboard skin, is the baffle width increased by 1/4" from the original design, or the internal width reduced by 1/4" (to maintain the same baffle width as originally designed)?

[technodanvan]

In the case of the Ardents Steve is working on, he kept the width of the cabinet the same and narrowed the interior while making the cabinet a tad deeper to compensate (aka, the right way). In my case, I elected to widen the baffle; I didn't want to mess with any of the parameters of the MLTL and I figured an extra 1/8" to each side would have minimal impact on a speaker that already has a small sweet spot due to the nature of the driver.

[technodanvan]

Well, it's been far too hot to really do any work this week so progress has stalled. I did sand down and coat my test piece with tung oil, which darkened the hardwood nicely. It's hard to take a picture of, but I think it'll look pretty good between the baltic birch and the paint I selected! I'm going to move forward with the padauk.

[Steve Manning]

Looking good Danny. I love the look of padauk, I just wish it stayed more on the red side rather than turn brown over time.

Come on Danny, it's a "dry" heat out there. Not as warm here, mid 90's but we're required to wear a heavy wet blanket along with it. Next shop will be having ac is all I have to say!

[technodanvan]

Come on Danny, it's a "dry" heat out there. Not as warm here, mid 90's but we're required to wear a heavy wet blanket along with it. Next shop will be having ac is all I have to say!

I might try to get out tomorrow morning for a bit, but I tend to sweat all over stuff if I'm not careful. I'd work in the afternoon (so hot sweat just evaporates) but then I have direct sunlight on tools and such which makes them a bit uncomfortable to use!

[JonMarsh]

Danny is uncomfortably close to the places that are setting records for how early in the morning it's hitting 100 degrees...

Maybe a tent would help, for some shade? I can't imagine using tools outdoors in those conditions. I'm a glutton for SOME kinds of punishment, but that would be beyond the pale...

[technodanvan]

Made some progress this morning before the sun had a chance to melt my work. Cleaned up excess glue and trimmed down the baffles to size. They're ready for driver cutouts now. Made a rabbet for the trim pieces in both cabinets; what a mess that was, HDF just gets everywhere. Discovered when I eyeballed the depth I took out a little too much, so a new sheet (panel?) of padauk is on the way from Rockler to compensate.

List of things to do before painting (this is for me!):

Cabinets:
1. Cut hole for terminals, drill out screw holes
2. Clean and round over port hole
3. Sand down that one trouble spot that won't go away
4. Cut and glue in trim.
5. 'trim' trim.
6. sand all edges - consider light roundover
7. completely clean interior of cabs with compressed air.
8. line cabinets with that foam that has hung around way too long and apply sealant
9. install excess wire in the cabs (extend through terminal cutout)
10. fill mid/lower cabs with stuffing as per guidance from Curt

Baffles:
1. Sand down front and back as necessary
2. Mark and drill out hole for Jasper jig in both baffles and a test piece (or two)
3. Create cutouts in test piece. Adjust as necessary
4. Create cutouts in baffles
5. Carve out rear of the cutouts for breathing room
6. Drill out mounting holes for drivers. Consider use of inserts.
7. Glue baffles to cabs

Final steps:
1. cover driver cutouts (and maybe port and terminal holes if #4 is a thing)
2. trim baffles if necessary
3. round over vertical edges of the baffle
4. again consider a light round over for the rest of the edges
5. sand/fill/sand/fill/sand/fill
6. take a nap.

[Steve Manning]

Yep, that hdf is just as messy as mdf when it comes to routering.

I should have the last of your finish this morning. The place I ordered it from last week discovered they didn't have any base lacquer on hand for tinting. I found out about that when only two out of three of the gallons I ordered showed up.

Of course that fits right in with the remainder of the week when my refrigerator died. New one is supposed to be delivered this morning .... I've been living out of coolers since last Thursday. Always something to get in the way of what I need to be doing like speaker work!

[JonMarsh]

Who says our pandemic luck has turned? Or, as the old saying goes, life is what happens while you're busy trying to make other plans!

[technodanvan]

.... I've been living out of coolers since last Thursday. Always something to get in the way of what I need to be doing like speaker work!

Oh man, I've been there before. Not fun.

[technodanvan]

Ordered a tool today to help with my sanding issue. Problem is I'm concerned I'd incidentally sand down other areas when doing this by hand and I need some level of precision. While this belt sander presents it's own issues with sanding (I mean, it's a belt sander) I like my chances better with it. Here's hoping I use it more than once because it wasn't cheap.



Also ordered one of these because every iteration of this device I've seen previously has been a cheap POS and I've needed something like it several times previously. Things like large furniture don't fit well under a drill press...

[Steve Manning]

Ordered a tool today to help with my sanding issue. Problem is I'm concerned I'd incidentally sand down other areas when doing this by hand and I need some level of precision. While this belt sander presents it's own issues with sanding (I mean, it's a belt sander) I like my chances better with it. Here's hoping I use it more than once because it wasn't cheap.

[ATTACH=CONFIG]31341[/ATTACH]

Also ordered one of these because every iteration of this device I've seen previously has been a cheap POS and I've needed something like it several times previously. Things like large furniture don't fit well under a drill press...

[ATTACH=CONFIG]31342[/ATTACH]

Nice, I've had my eye on that drill guide for a while now. Interesting looking sander, I've not seen that before.

[technodanvan]

Nice, I've had my eye on that drill guide for a while now. Interesting looking sander, I've not seen that before.

Yeah, I've been watching it a while too. I feel like there should be a device in the $75-$100 range that would provide some level of durability and consistency, but this is the first one I've seen that looks like it'll last. It'll probably be one of the few purchases from Woodpeckers that I'll actually use so the price is easier to swallow.

Based on the images associated with the sander I think it might be intended for bodywork on cars. I see sandpaper available from at least 60-400 grit, so I think it'll work for my intended purpose.

[Scareurpasenger]

The Rockler one looks promising as well. https://www.rockler.com/rockler-portable-drill-guide

[technodanvan]

The Rockler one looks promising as well. https://www.rockler.com/rockler-portable-drill-guide

That looks a lot more versatile, though I don't see myself drilling angled holes anytime soon. I do really like the addition of the handle though, I wonder if it's reversible for those of us that are left handed.

[Mr.Ed]

That looks a lot more versatile, though I don't see myself drilling angled holes anytime soon. I do really like the addition of the handle though, I wonder if it's reversible for those of us that are left handed.

You mean for those of us that are ‘correct’ handed.

[CADman_ks]

...

Based on the images associated with the sander I think it might be intended for bodywork on cars. I see sandpaper available from at least 60-400 grit, so I think it'll work for my intended purpose.

I don't know that it's the "intended" use, but we use them a lot at work, where we work with metal. While they work for what they do, and there's probably not a good substitute, they probably have two disadvantages:

1) We are using them with coarser sandpaper, because of the metal stuff. But, they can blow thru some material quickly, and they leave gouge marks very easily, because you're sanding a narrow strip
2) They are HARD on sandpaper, and it doesn't last long on there. Again, that could be because we are using them on metal, and they might last longer on wood

All-in-all, as a purpose built tool, they are excellent. Obviously, they don't work like belt sanders though, and don't work well for say, leveling a table top.

[technodanvan]

Thanks CADman, that is helpful. I think I may order some higher grit sandpaper to hopefully avoid said gouge marks. I see this model does have a speed adjustment on it (which is good, since the examples I see appear to run at a fairly high RPM) so I'm hoping a low setting coupled with a high grit belt will result in what I want.

[CADman_ks]

Thanks CADman, that is helpful. I think I may order some higher grit sandpaper to hopefully avoid said gouge marks. I see this model does have a speed adjustment on it (which is good, since the examples I see appear to run at a fairly high RPM) so I'm hoping a low setting coupled with a high grit belt will result in what I want.

One thing that I didn't mention about the ones that we use at work, was that they air driven, and because of that, they do not have speed control. Actually, I think that having speed control on something like this would help quite a bit.

Getting some higher grits is not a bad thing either.

GOOD LUCK!!

[technodanvan]

Hope you all had a wonderful 4th. Mine was spent trying to keep my dog calm for the most part...we are not a huge fan of celebrations others put on. I did, however, have a long weekend to work on this project so I took advantage by spending 1-2 hours each morning before stopping when I ran out of sweat.

Terminal cutouts and rounding over the port...


Baffles more or less ready...(see below)


Dusty day...


Trim in place...


Marking holes for inserts...


The observant among you may have noticed the driver is not going to be flush mounted. In a world of compromises I decided this would not be hugely important. The problem I encountered was the noted through hole diameter vs the flush mount diameter (7 3/16" vs. 8 3/4"). I didn't notice it until it was too late, but basically this requires a rabbet bit exceeding 3/4" - which I do not have, nor do I see a set available that goes that far (my sets give me all sizes in 1/16th of an inch up to 3/4). I considered expanding the size of the through hole by using a 1/16th rabbet followed by a flush bit (and technically I'm still considering it) but it was getting late in the day (10 AM) and I was hot and tired. Today I didn't feel any more strongly about it either. We'll see, considering the effort expended on the rest of the project it might be worth going that extra mile. Maybe.

For anyone else considering the Singularities I would recommend either making your OD first using a circle guide OR just making the through hole 7 1/4" (if you have a big enough rabbet) - there would be plenty of meat left over for the screw holes anyway.

[technodanvan]

This was also my first opportunity using a large custom chamfer bit someone at PE had made. It wasn't really necessary since the baffles weren't attached yet, but it was the biggest chamfer I had and I figured I might as well use it.

Turns out about anything would have worked because the PS220-8 has ample room to breathe already.





Oh, that little sander worked perfectly, and has been handy for things like sanding down the interior of holes and removing that final piece of wood left when cutting circles. I don't think I'll ever use anything but the lowest setting though, even that removes material remarkably quickly. True to form I suppose.

Anyway, the next steps are installing inserts (on the way from Amazon) and finishing up the trim. I'm almost to a point where no more sawdust is necessary and I'm looking forward to it. Of course, my next project is already sitting in boxes on a shelf so that won't last long.

[JonMarsh]

Ordered a tool today to help with my sanding issue. Problem is I'm concerned I'd incidentally sand down other areas when doing this by hand and I need some level of precision. While this belt sander presents it's own issues with sanding (I mean, it's a belt sander) I like my chances better with it. Here's hoping I use it more than once because it wasn't cheap.

[ATTACH=CONFIG]31341[/ATTACH]

Also ordered one of these because every iteration of this device I've seen previously has been a cheap POS and I've needed something like it several times previously. Things like large furniture don't fit well under a drill press...

[ATTACH=CONFIG]31342[/ATTACH]

That. drill guide looks quite a bit better than some of the others I've bought- saved for future reference.

[CADman_ks]

...

The observant among you may have noticed the driver is not going to be flush mounted. In a world of compromises I decided this would not be hugely important. The problem I encountered was the noted through hole diameter vs the flush mount diameter (7 3/16" vs. 8 3/4"). I didn't notice it until it was too late, but basically this requires a rabbet bit exceeding 3/4" - which I do not have, nor do I see a set available that goes that far (my sets give me all sizes in 1/16th of an inch up to 3/4). I considered expanding the size of the through hole by using a 1/16th rabbet followed by a flush bit (and technically I'm still considering it) but it was getting late in the day (10 AM) and I was hot and tired. Today I didn't feel any more strongly about it either. We'll see, considering the effort expended on the rest of the project it might be worth going that extra mile. Maybe.

...

I noticed that you replied to the woodworking advice thread that you had the same set of bits (or similar) to the ones that I have that have the different bearings for different rebates. If I did the math correct, you're only .031 off of where you need to be at the .75 rebate. What if you just put the bolt in there (or get another sacrificial one), and used that as your pilot? My dad used to have a set of bits that didn't have bearings, while not the greatest, they do work if you're moving pretty quickly. That would at least allow you to recess the drivers, if you're so inclined...

[technodanvan]

You know I thought about that too, or even just running the bearings without a spacer. It might give me just enough to get there...something i will probably try after I'm done installing the trim.

That. drill guide looks quite a bit better than some of the others I've bought- saved for future reference.

Keep in mind you could get a drill press for about the same price (I think my Porter Cable was about that much) so if you no longer have space constraints it may be a better purchase in the long run unless you're making furniture or something. I was also thinking about using it for threaded inserts though - slap a ratchet on the top instead of a drill and you've got a way to make sure they stay straight while not wearing out your wrists. It'd only work on level surfaces of course, but I think it could be done.

[CADman_ks]

You know I thought about that too, or even just running the bearings without a spacer. It might give me just enough to get there...something i will probably try after I'm done installing the trim.

...

Yeah, you are SO close, it would be a shame to not rebate them, especially when you "almost" have the right tool.

[Steve Manning]

You know I thought about that too, or even just running the bearings without a spacer. It might give me just enough to get there...something i will probably try after I'm done installing the trim.



Keep in mind you could get a drill press for about the same price (I think my Porter Cable was about that much) so if you no longer have space constraints it may be a better purchase in the long run unless you're making furniture or something. I was also thinking about using it for threaded inserts though - slap a ratchet on the top instead of a drill and you've got a way to make sure they stay straight while not wearing out your wrists. It'd only work on level surfaces of course, but I think it could be done.

You could also make a template out of mdf, attach with doudle sided tape and use a flush trim bit to do the rebate. I've had to do that on a few occassions, it works rather well.

[technodanvan]

Alright alright, I guess there are several options available to a person who isn't a lazy shmuck. I'll get it sorted.

[Mikerodrig27]

I shoot a couple of pin nails through the template through the baffle to make certain it won't move. 18 gauge or 23 gauge. I had a template slip once, never again.

[technodanvan]

Good call Mike. This is why posting a build log is worthwhile - for you and everyone else to keep me from making mistakes!

[technodanvan]

You could also make a template out of mdf, attach with doudle sided tape and use a flush trim bit to do the rebate. I've had to do that on a few occassions, it works rather well.

Hey Steve, what sort of double sided tape do you use? One of those kinds that is easy to pull off or something a bit more secure? I'm a bit worried about scraping it off the baffle if it's the latter.

Edit: I'm a bit afraid to use the pin nail method since this baffle isn't going to be veneered or something to cover the hole.

[CADman_ks]

I shoot a couple of pin nails through the template through the baffle to make certain it won't move. 18 gauge or 23 gauge. I had a template slip once, never again.

That's a GREAT idea! I have a side hustle building corn hole boards, and I use a router with a flush trim to cut the 6" hole. I recently had one move on me while routing, and luckily, I was able to salvage the piece, but the hole was quite in the correct spot, but close enough.

That is frustrating when templates move!!

[Steve Manning]

Hey Steve, what sort of double sided tape do you use? One of those kinds that is easy to pull off or something a bit more secure? I'm a bit worried about scraping it off the baffle if it's the latter.

Edit: I'm a bit afraid to use the pin nail method since this baffle isn't going to be veneered or something to cover the hole.

Hey Danny ...... I've actually been getting away doubled sided tape because of the mess left behind. I've been using CA glue and painters tape for the CNC and it works rather well. Check out this video, https://www.youtube.com/watch?v=wern6Cj8sgI

[technodanvan]

That's really interesting Steve, I never would have thought of it! I had considered using some double-sided tape that is designed to come back off but it sounds a little scary to risk the baffles that way.

I have, however, thought of just cutting the template to be the same width as the baffle and simply clamping it together...

[Steve Manning]

That's really interesting Steve, I never would have thought of it! I had considered using some double-sided tape that is designed to come back off but it sounds a little scary to risk the baffles that way.

I have, however, thought of just cutting the template to be the same width as the baffle and simply clamping it together...

I would not have thought it would work either, but it does. I'm applying a lot more force with my CNC than you would by hand as well. If you make the template larger enough you could also add some clamps as well. Here is another video of them using to machine metal. https://www.youtube.com/watch?v=r6DCvtcU8_M