My Nat P build, questions on bass bins and finishing.

[BigJim_inFLA]

I'm building a pair of Nat P's for myself and they are coming along pretty well. I do have a few questions, however.

1. I plan to use these with bass bins and a sub, can I leave them sealed or should I still port them?

2. I searched for bass bins and found alot of talk but few who actually finished them. Has anyone beside speedle paired these with bass bins? If so how do you like them? I'm planning to use the RSS315-HF but I'm not sure if I should use one per side or two. Also how much volume would a sealed box need for either of these configurations?

3. I've veneered these with cherry, it looks very nice, but I've never worked with cherry before and I've heard it takes stain very unevenly. Has anyone used cherry with good results and if so how did you finish it? I like the look of it now and would just like to bring out the grain a bit and perhaps get it slightly darker. Any suggestions?

Thanks for the help and for all the great info I've found here.






Jim

[wkhanna]

First of all, those look absolutely beautiful, Jim!
I really like the way you designed your internal braces.

As far as porting, IIRC, advise was given by our moderators that porting is advisable if you don’t have base bins or a sub to get a little more LF extension.

Concerning the finish on the cherry, it has been a while since I have done any, but with a quality wood like that, my personal preference would be tongue oil. I like a minimal approach to inherently sensuous woods like cherry.

[orbifold]

Jim, have you ever played with shellac? If you have any left over cherry you can attach to some mdf or whatever, experiment with some shellac thinned 3 or 4 to one with denatured alcohol (3or4 is the alcohol.) Then stain. This is the best way I've found to reduce blotch. I used it on some maple shelves and also on pine trim in the same room. The pine was even and that's not possible any other way that I know of. The stuff dries almost instantly and sands beautifully. I'd use it for a final finish, but it's not durable in that role. You won't get as much color from a given stain, but it sounds like you might be going light anyway? There's also the orange variety of shellac that will make things a bit darker. You can use polyurethane over this if the poly is good quality and you tack rag carefully. I would spray some kind of other finish. I like a thing called pre-catalyzed lacquer. It can be hard to find and you have to use lacquer thinner, but it wears like kid's furniture ought to.
There are oils that bring out grain very well, and you use a completely different top coat. Maybe someone else can give speak on that. I haven't used them.

[Martyn]

Cherry can go blotchy with a stain. If you don't want to go much darker than they are now, just give them a wipe with mineral spirits to see what they'll look like when oiled. Remember that they'll darken with time anyway.

Tung oil is easy to apply and leaves a pleasant "soft" finish. Danish oil is almost as easy but will build to a sheen more quickly, if that it what you want.

[bob barkto]

Cherry will darken considerably on exposure to air and uv light.
Leave them un-finished for a week and you'll see the color come back.
Oils, oil based varnish and some lacquers will do a fine job of accentuating and preserving the color.

Avoid nitrocellulose and acrylic lacquers and also most water based varnish/poly as these finishes tend to have a bleaching effect on wood.

Tung oil is fantastic on natural cherry btw and is easy to apply and very durable. You can produce anything from a dull sheen to high gloss just by wiping and rubbing.

Linseed oil tends to darken a bit as does Watco/Danish oil (they contain mostly linseed oil). But both can look very nice with the soft shine linseed produces.

Experiment!!

3. I've veneered these with cherry, it looks very nice, but I've never worked with cherry before and I've heard it takes stain very unevenly. Has anyone used cherry with good results and if so how did you finish it? I like the look of it now and would just like to bring out the grain a bit and perhaps get it slightly darker. Any suggestions?

Thanks for the help and for all the great info I've found here.

Jim

[WinstonSmith]

I suggest boiled linseed oil, followed by shellac when dry then Original Waterlox.

looks like this:

[speedle]

Jim

First off, your nat cabs look truly fine, very nice curves on the front there. My hat is off to anybody who makes great looking boxes. :T

I used the recommended cab size of 1 cubic foot, but left them sealed. They roll off very smoothly in the 100 to 60 Hz range, and I've found it very easy to integrate with my sealed bass bins. Mine are powered by the 300 watt bash amps from PE, and after a little fiddling with level and crossover freq., I found a pretty good medium and am very happy. You just have to pay attention to what listening axis/height you'll need as you are designing the bottom half of your setup.

As to cherry, I actually plan to re-veneer my Nats in cherry because I don't like the way the luan over MDF turned out. I have always liked a medium cherry tone, and plan to just tung oil the veneer after a good sanding.

BTW, if you wanna see blotchy, try staining birch plywood!

[Brian Bunge]

Jim,

I really like the boiled linseed oil on cherry. I mix it 1/1 with naphtha to help it dry more quickly. I can do 4 coats in a day and then apply the first of several coats of wipe-on poly the next day.

For staining cherry, I've used Minwax's water-based prestain and then used Behlen Solarlux dyes. I really like the medium red mahogany on cherry and maple.

[BigJim_inFLA]

Thanks to all for your ideas. I have quite a bit of left over cherry so I think I'll be trying most of your suggestions out to see which I like the best. I did make a wonderful discovery today! In searching for some of the suggested products that I couldn't find at Lowe's or HD, I found that I live only 10 mins from a Woodcraft! :B They have everything a woodworker could want from power tools, to finishes, to exotic woods...I wanted to just run in and pick up a few things but ended up wandering around for almost an hour just looking at everything. The salesman I spoke to also suggested some finishes, all ones already mentioned here. I be sure and let you know which turns out best.

Jim

[wkhanna]

In searching for some of the suggested products that I couldn't find at Lowe's or HD, I found that I live only 10 mins from a Woodcraft!
Jim

Holy crap!!! I just did a search and found one 15 minutes from my place; I never knew anything about this store till just now! Thanks Jim!

[Brian Bunge]

Jim,

Yep, I know exactly where the WoodCraft is you're talking about (On 436 in Casselberry, I believe not too far from I-4). Pisses me off completely that that is the closest store to me now that I'm down in Palm Bay.

[BigJim_inFLA]

Yep, I know exactly where the WoodCraft is you're talking about (On 436 in Casselberry, I believe not too far from I-4). Pisses me off completely that that is the closest store to me now that I'm down in Palm Bay.

Yes that's the one. If you ever get up this way to shop stop by.

Now for the hard questions, at least for me. I'm trying to determine the correct volume for my bass bins. I'm going to use the RSS315-HF. I read Speaker Building 201 and used the formula to determine the volume that would give me a Qtc of 0.707 and I came out with a volume 1.73 cu. ft. So my questions are:

Is a Qtc of 0.707 what I should be using?

Does this volume sound right for this driver?

If I wanted to use two of them per side would I just double the volume?

Also how important is placement of the driver(s) on the baffle for bass bins? Should the driver be centered on the baffle top to bottom, or should it be closer to the top of the baffle to minimize reflections from the floor?

[Brian Bunge]

If that's the Qtc you want, then yes, that's the right volume to shoot for. Honestly, I prefer a lower Q design. I prefer to design for somewhere in the .6-.65 range. The problem with this is you are looking at roughly 2.5ft^3 (.65) to 3.5ft^3 (.6) for those values. If you are planning on using these below 100Hz then I'd suggest looking at the HO series. The want a much smaller enclosure for the same Qtc. For a pair of HO's in a single enclosure you can use 2.6ft^3 for a Qtc around .6 or so.

BTW, what are you using for a separate sub if these are strictly bass bins?

[speedle]

Good start! I generally concur with Brian, especially about low Qtc. I modelled the heck out of mine before I really got settled on what I wanted to do. Since my ears were "trained" on slightly boomy acoustic suspension bass (as opposed to boomy, badly ported bass!), I went for a bit higher q , but I've really come to appreciate the tightness that a lower q will get you. Are these strictly for music? What general shape are you looking at? Remember to think about the listening axis and where you're going to be sitting, etc. My bins are roughly 3 cu. ft. and stand about 32" tall without spikes.

One more thought, on floor reflections. It's good to keep in mind, especially if you go with only one driver, that lower to the floor is generally better, but I've found it more difficult to "blend" sonically with the top cabs. But, some of that will depend on where you cross over to the Nats, and how high off the floor they end up being. Lots of factors to balance, that's for sure.

[BigJim_inFLA]

I only chose 0.707 because the book lists it as a good compromise between bass response and transient response. I'm farily new to this so wasn't sure what to shoot for. As far as size goes I'm not sure that I can't go down to 0.65 with the HF. I have a tall sofa and I'm pretty tall as well, keeping the tweeter near ear height and placing the Nat p's on top of the bass bins I can still build them about 35" tall. An enclosure 14.5 x 22 x 35 outside dimension would still give me about 4.6 cu.ft. after accounting for wall thickness, bracing, and the drivers. A Qtc of 0.65 gives me a Vb of 2.31 cu. ft. for one driver. If I'm doing the math correctly that still might work.

For a sub I have a RLp-15 in a sonotube with an EP2500 for power. That was my first DIY build and since then it has become somewhat of an addiction. This is my 5th set of DIY speakers, but all have been proven designs from the forum, I haven't tried to design anything yet.

[dlneubec]

Jim,

I really like the boiled linseed oil on cherry. I mix it 1/1 with naphtha to help it dry more quickly. I can do 4 coats in a day and then apply the first of several coats of wipe-on poly the next day.

I agree with this for cherry. I did my NaO Mini's below with this finish and they have a combination of cheery and maple on them.

Image not available

[BigJim_inFLA]

Thanks speedle. Let me give as much info as I can:

Seated ear height 50"

Speakers will be 11' apart
11' from listening position
3' from back wall
3' from side walls

Room is 16' x 28' with vaulted ceilings (8'-15').

Use will be 60% music 40% HT.

Other speakers currently in use:
Modula MT surrounds
RS 3 way WMTW center channel
Current mains that will be replaced (and for sale) Klipsch Chorus II which have mid and tweet horns and 15" woofer with 15" PR
RLp-15 sonotube sub

I believe I saw on another thread suggesting to cross to the bass bins in the 150Hz to 250Hz range so that was what I was shooting for.

What general shape?? I guess standard rectangle, similar proportions to the Nat P's that will be on top of them, only bigger.

If there is anything else that would help just let me know. Thanks.

[BigJim_inFLA]

I agree with this for cherry. I did my NaO Mini's below with this finish and they have a combination of cheery and maple on them.

Very nice!! I like the cherry on those very much and I have already tried a test panel with that technique. It was pretty easy and got good results. My girlfriend does get a vote though and she wants something a bit more red. Maybe I can talk her out of it. :B

[speedle]

Ah, the famous SAF.

Boy, your ears are up high off the ground! Maybe I just slouch too much...

With a 50" listening height, you'll have much less "downward" aiming to do than I did, maybe even exactly none, given your listening distance. That really is to your benefit, you won't end up with any compromises in the radiation pattern, and it gives the wavefronts a little more time to integrate better.

By general shape, I was thinking of my own case, where I wanted to keep roughly the same proportions as the Natalie P's, while making sure the whole thing looked "grounded" and wasn't too tall. In the end, I could have gone for a bit more depth with less height, because width was generally maxx'ed out (get it?) at 16". I know, bad pun. :Z

And I love that cherry too!

Are you going to actively cross the high pass to the Nats, or just let the sealed box roll off on its own? For HT, you probably would want to get the lows outta there asap, but there are varying opinions on that I'm sure.

[BigJim_inFLA]

SAF is not too much of a factor, really. She doesn't live with me, but when I ask her opinion it makes her feel better. :B

Boy, your ears are up high off the ground! Maybe I just slouch too much...

With a 50" listening height, you'll have much less "downward" aiming to do than I did, maybe even exactly none, given your listening distance. That really is to your benefit, you won't end up with any compromises in the radiation pattern, and it gives the wavefronts a little more time to integrate better.

I guess being freakishly tall finally pays off!

Are you going to actively cross the high pass to the Nats, or just let the sealed box roll off on its own? For HT, you probably would want to get the lows outta there asap, but there are varying opinions on that I'm sure.

I'll be actively crossing with a Behringer CX2310.

Jim

[BigJim_inFLA]

I got my crossovers finished this weekend! Could have done more but I finally got my first HDTV and have been mesmerized by DiscoveryHD. I really can't stop watching it.

[digital desire]

Looks nice!
I don't think I have seen mirror image crossovers before!
(If I have, I did not notice...)

[wkhanna]

V nice work, Jim!

[BigJim_inFLA]

Here they are! Thanks to all the good suggestions for finishing. I ended up using 3 coats of boiled linseed oil thinned 50/50 with naphtha, 3 coats of button shellac with just a bit of transtint bordueax dye in the shellac, finished off with 2 coats of original Waterlox. I think they look better in person than in the picture, I guess I have to statr working on my photography skills.



Jim

[digital desire]

Wow, I *really* like that finish!
Nice Job!

[wkhanna]

Marvelous, Simply Marvelous!!!!
Of course, it is your opinion that matters the most, but I think you should feel pretty good!

Coincidently, I just bought a bottle of TransTint Bordaeux, myself today at Woodcraft!
I’ll be using it on the solid poplar baffles and Baltic Birch cabinets I made for my new ‘Twins’, the Nat P’s.

[BigJim_inFLA]

Thanks guys.

Coincidently, I just bought a bottle of TransTint Bordaeux, myself today at Woodcraft!

Gotta love Woodcraft! Go easy with that Transtint dye. I only used 3mL of it to tint just under 1 quart of shellac and the difference was quite noticeable. If you plan to use it mixed per the label as a dye I woud imagine the results would be much more dramatic. Can't wait to see how yours turn out.

Jim

[wkhanna]

I tried some techniques today.

Top section on inner Baltic Birch baffle is 3 coats of tung oil.
Section below is 1 coat of tung oil, the tint over top of it, with 2 coats of tung oil on that.
Bottom section is 1 coat of tint on the bare birch, with two coats of tung oil afterward.

[Ecir38]

big jim and wkhanna, getting it right and taking the time to do so is going to pay off a ton, looks great!!!

[BigJim_inFLA]

THEY ARE DONE!! And they sound great! Of course I still need to build the bass bins, but for now they can live next to my TV.

[---k---]

Looks great. Very impressive finish. I bet they do look even better in person.

Oldly though to me, your NatPs look visually smaller than most I see posted. I guess that is a good thing.

[JonMarsh]

Looks great. Very impressive finish. I bet they do look even better in person.

Oldly though to me, your NatPs look visually smaller than most I see posted. I guess that is a good thing.

Well, that's a "BIG" CC speaker (the RS WTMW Dawaro and others have built), and a pretty good size LCD. I use a smaller CC as the base in my bedroom for my Westinghouse- Modula MTM's look bigger then, though. It looks like he's used the same cabinet size as the original PE cabs, whereas many folks up the size to get more bottom end.

Very nice looking results! :T

And a nice job on your crossovers, too. I'm thinking about making some PCB designs for this network.

~Jon

[Finleyville]

Jim,

They look great! I am finishing some custom baffles for some PE enclosures, and I hope that they turn out as good as your work. Enjoy!

[wkhanna]

Of course I still need to build the bass bins..........

It never ends, does it!

Honestly, I think if you told anyone you built those, they would not believe you. They are just too good looking!

[BigJim_inFLA]

Thanks everyone. I'm very happy with the results, looks and especially the sound! Thanks to Jon for the kind words and for designing a great speaker, and to everyone else who helped me along the way.

It never ends, does it!

No it doesn't. Let's see, bass bins, finish the TMWW's for my dad, my Modula MT's are still bare MDF, and I'd like to try my hand at designing a 2 way, and then there is the Isiris...

I just started a part time job just to support my audio habit.

Jim

[speedle]

But damn! Those are sweet looking boxes, let me tell you ;x(


I knew there was a reason I ordered new veneer for mine, and there it is!

[BigJim_inFLA]

Thank you! I just hope I can get the same finish on a MUCH bigger box. I started my bass bins today...34.5" x 22" x 15.5". I'm not sure how I'm going to veneer these. For the Nat's I used a single sheet of veneer wrapped around the front and both side, but as big as these are I can't cut a single piece that long and still have the grain run in the correct direction. Is it a simple matter to butt two pieces together or will it be noticeable? I can get 8' x 4' cherry that has the grain running in the 4' direction, but it is 20 mil instead of 10 mil. Will 20 mil paperbacked wrap around a 3/4" roundover just as nicely as the 10 mil? I'll have pics soon!!

Jim

[BigJim_inFLA]

One bass bin is almost complete! I should have it completed except for the veneer this weekend. Since this is my first attempt at something that wasn't already designed by someone else I'm gonna get one together and see how it sounds before I start the next. If I have to I can scrap the box and try something else. Oh by the way, this thing is BIG! 8O

Jim

[wkhanna]

NO moss growing on the bottoms of your shoes, Jim.
You Go, buddy!

[speedle]

Just how "big" would big be? And what's going inside?

[BobEllis]

Big? I'd bet Kingpin would call them "cute". Looking good so far.

[BigJim_inFLA]

Just how "big" would big be? And what's going inside?

It is 34.5" x 22.5" x 15.5". It is currently lined with fiberglass and will probably also get some polyfill depending on how they sound when assembled. I'll be using 2 RSS315-HF 12" drivers. I'm going out to route the baffle right now, should be together by this evening!

Big? I'd bet Kingpin would call them "cute". Looking good so far.

True that, but some of us aren't quite as crazy as he is. :B

[RPiatt]

Wow...

Those cabinets are beautiful. Stunning even. :E

Excellent work...

[BigJim_inFLA]

Ok, one is done! I'll be spending the rest of the evening trying to get it set up, never used an active crossover before.

So what is the best way to move a speaker that weighs over a hundred pounds with really sharp spikes on the bottom?

[ThomasW]

So what is the best way to move a speaker that weighs over a hundred pounds with really sharp spikes on the bottom?

Remove the spikes, reposition the speaker. Once repositioned, rock the box backwards and insert the front spikes, then lean it forward and insert the rear spikes.

2"X4"s work great for leveraging a speaker with spikes up or down.