NatP Journey Begins

[mischmat]

Ply is in and it starts. Quick question on port. I'm going to do slot but need to double check if I have to add volume to the cab to compensate for the slot port or if I can stick with the original 1cu/ft design.

Calculated port to equal out the 2" x 9" round port suggested in the build for a tuning of 34Hz is 28.27 cu/in.
Slot port calculation is 7.5" x .75" x 5" netting a volume of 28.125 cu/in.

[JonMarsh]

If the volume of your slot port is comparable to the volume of the conventional port, then no worries. Keep in mind, though, that the "standard" Natalie in 1 cu ft is the 'easy to build, not fully optimized" version, as regards bass response, and many users have built larger tower versions, main difference being enclosure volume, that have done well in open class competition at DIY meets. By "doing well", I mean winning in at least one case...

Use the search function for more info- I'm working this Sunday, and don't have time to go through the posts myself.

Good luck with your build, keep us posted, and come back here with any other questions.

[Ray_D]

Ply is in and it starts. Quick question on port. I'm going to do slot but need to double check if I have to add volume to the cab to compensate for the slot port or if I can stick with the original 1cu/ft design.

Calculated port to equal out the 2" x 9" round port suggested in the build for a tuning of 34Hz is 28.27 cu/in.
Slot port calculation is 7.5" x .75" x 5" netting a volume of 28.125 cu/in.

I assume you are dealing in liters, not cubic inches. One cubic foot is about 28 liters. Fractional liters do not matter. Usually, the slot port would be almost the same length as a circular port. The areas should, to first order, be the same. If you are going to build a floor stander, larger would be better. Do you have Unibox? http://audio.claub.net/software/kougaard/ubdwnld.html

[mischmat]

These won't be the floor standers. I had a set of Dynamic 4T's that lost the WAF factor so I'm going to do a bookshelf.

I'm glad you said something about length of port. I was going to go the width of the cabinet for the slot port but now I just realized it's not just volume of the port but the length is what tunes the frequency. So take into account the extra thickness of the ply, I'd have to think the loss of volume in the cab is minimal and shouldn't affect tuning too much. Maybe raise it a touch. Either way it'll be pair'd with a HSU research VTF3-MK2 sub, should cross over well ~50hz

[fbov]

I've built both low-tune ported and sealed NatPs, using both shielded and unshielded drivers. You likely have shielded, assuming you're re-purposing the 4Ts' drivers.

The only trick to slot ports is the presence of nearby walls where it opens inside the box. I did a rear bottom port, and added 1/2 port width to my effective length for the contribution of the back wall. The port width was less than internal width, so I didn't do a side correction. That said, port length is not a strong driver of tune; you're not likely to hear a 3/8" correction on a 7.5" x .75" x 5" port.

And with a sub, I'll question if you want to port them. My Unibox modeling shows an F3 of 72Hz for sealed, while I can't break 47Hz in a ported 28L box. Make that a 56L box and a 35Hz tune makes sense.

My towers are 65L, tuned to 32Hz. They came in second to these (but sounded way better).

Have fun,
Frank

[mischmat]

I've built both low-tune ported and sealed NatPs, using both shielded and unshielded drivers. You likely have shielded, assuming you're re-purposing the 4Ts' drivers.

The only trick to slot ports is the presence of nearby walls where it opens inside the box. I did a rear bottom port, and added 1/2 port width to my effective length for the contribution of the back wall. The port width was less than internal width, so I didn't do a side correction. That said, port length is not a strong driver of tune; you're not likely to hear a 3/8" correction on a 7.5" x .75" x 5" port.

And with a sub, I'll question if you want to port them. My Unibox modeling shows an F3 of 72Hz for sealed, while I can't break 47Hz in a ported 28L box. Make that a 56L box and a 35Hz tune makes sense.

My towers are 65L, tuned to 32Hz. They came in second to these (but sounded way better).

Have fun,
Frank

Maybe I'm reading the original post wrong. I took it as the 28l cab tuned at 34Hz. As for having them ported I would like to port them for the extra extension. My sub is used as an end table so I do run it a bit lower and rely on fronts for some extension.

Would I be better off recalculating the port to original lengths then or will I get the same tuning using the 7.5" x .75" x 5" port.

[JonMarsh]

Maybe I'm reading the original post wrong. I took it as the 28l cab tuned at 34Hz. As for having them ported I would like to port them for the extra extension. My sub is used as an end table so I do run it a bit lower and rely on fronts for some extension.

Would I be better off recalculating the port to original lengths then or will I get the same tuning using the 7.5" x .75" x 5" port.

You can tune lower, but it's like an EBS alignment. If you have them positioned out in a room, so that you get the right boundary lift, (think Cardas recommended placement) then you can get closer to flat. IF you're going to use them with a sub, there's not much point, but tuning them low running full range helps prevent the woofers from unloading with low frequency material. In your case, using it with a sub, it's pretty much all immaterial, depending on where you want to put your crossover point. If below 100 Hz, optimize the porting so that you get best response blending. If it's at about 100Hz, then it's a moot point ported versus sealed.

[mischmat]

Plugged some numbers into winisd, and came up with this.

28L tuned to 45Hz
Slot Port 1" x 7.75" x 7"

Gives me an F3 of 46Hz, which falls nicely into my sub. How's this look, with the port on the front side, or maybe top?

[speedle]

Is there any particular reason for not using a conventional tube port?

[mischmat]

Is there any particular reason for not using a conventional tube port?

Putting the IY in DIY

[JonMarsh]

Plugged some numbers into winisd, and came up with this.

28L tuned to 45Hz
Slot Port 1" x 7.75" x 7"

Gives me an F3 of 46Hz, which falls nicely into my sub. How's this look, with the port on the front side, or maybe top?

I think you've got the right idea... but why not put the port on the back, if they're stand mounted? If you think you do need them near a rear wall, the port isn't going to be your only problem, considering the baffle step compensation in the crossover...

[mischmat]

I think you've got the right idea... but why not put the port on the back, if they're stand mounted? If you think you do need them near a rear wall, the port isn't going to be your only problem, considering the baffle step compensation in the crossover...

They'll probably be closer to the walls, at least in this particular point in time. I decided on putting the port on the front, which brought the size up slightly and finished up creating the boards for the baffles. I have a new respect for the guys doing the large translam builds. I plan on keeping these ones for a while, and placement will most likely change so I didn't want to mess with the XO. I figure I could EQ it out with my amp. It has a 7 band parametric.

Just hope my top didn't get ruined. It rained and I forgot to bring it in. I have in clamps again till it's dry to prevent warping but we'll see.

[mischmat]

On my way.

[JonMarsh]

Cross fingers regarding the top... :uhoh:

[mischmat]

Cross fingers regarding the top... :uhoh:

All good. Was a bit of overhang that was taken down to flush.

[TEK]

Nice!
Are you going to keep the sides as they are, or translam them as well?
BTW, what finish are you planning? I came over this a different place, and have to say that this translam finish looks pritty slick (if you are going dark)

[5th element]

Looking good

[mischmat]

Nice!
Are you going to keep the sides as they are, or translam them as well?
BTW, what finish are you planning? I came over this a different place, and have to say that this translam finish looks pritty slick (if you are going dark)

The plan was to leave the sides to break-up the look. I like the idea of the straight lines looking at it front to back if you notice the side grain on the ply is horizontal. I'm stuck on a finish that'll match my house. My flooring, and trim are fir so they are on the darker side but not with the chocolate colouring as above but more orange. I think I have a pic from my dynamic 4t build that you can see. But dang those line array's look beaut. You wouldn't happen to know what stain and how those were finished do you?

Actually looking at the forum, on page 2 the right side example is more of a colour that'll match the house. Google translate isn't all the forgiving though to find out the colour

[mischmat]

Flooring and trim pic Post 13

Here's an example of the wood in my home.

Example on right is the colour I'm after that looks to match very well.

[TEK]

Hi

You can find more information about the speakers in the above picture here:

http://www.diyaudio.com/forums/full-range/242171-making-two-towers-25-driver-full-range-line-array.html

I assume you will be able to find exact information about his finish in that thread.

You should note that these now are covered in fiberglass and painted black because the translam broke up - likely due to usage of metal roods that did not flex as the wood flexed - but that's a different topic and not so much about the finish.

When it comes to the example you referred to.
He have used "3 Stjerners skyggegrå gulvolje og lakket over med Gjøco blank lakk".
That means that he has used a norwegian flooroil (kalled 3-stjernes) in shadowgrey color. Over that he has added a oilbased clear coat from another supplier called Gjøco.

So basically floor oil in wanted color with clear coat on top.

I will guess this is the exact clear coat he was using: http://www.gjoco.no/nb-NO/Produkter/...ljebasert.aspx
And the floor oil should be avilable here, but the site seems to be down right now: http://trestjerner.no/
(both links are in norway - so I'm not sure if they give you any valuable info)

[mischmat]

Hi

You can find more information about the speakers in the above picture here:

http://www.diyaudio.com/forums/full-range/242171-making-two-towers-25-driver-full-range-line-array.html

I assume you will be able to find exact information about his finish in that thread.

You should note that these now are covered in fiberglass and painted black because the translam broke up - likely due to usage of metal roods that did not flex as the wood flexed - but that's a different topic and not so much about the finish.

When it comes to the example you referred to.
He have used "3 Stjerners skyggegrå gulvolje og lakket over med Gjøco blank lakk".
That means that he has used a norwegian flooroil (kalled 3-stjernes) in shadowgrey color. Over that he has added a oilbased clear coat from another supplier called Gjøco.

So basically floor oil in wanted color with clear coat on top.

I will guess this is the exact clear coat he was using: http://www.gjoco.no/nb-NO/Produkter/...ljebasert.aspx
And the floor oil should be avilable here, but the site seems to be down right now: http://trestjerner.no/
(both links are in norway - so I'm not sure if they give you any valuable info)

From what I can find on the site, I believe the right test he did was the 2040 Cinnamon colour, and he ended up using a dark Chestnut? as his final finish before things went south and the boxes cracked. I'll have to get some samplers and give it a go but if my monitor colours are correct and the pictures on google images are accurate I think a Cinnamon stain might just be the ticket for me.

[TEK]

Good luck, looking forward to see how it turns out!

[mischmat]

Question on how true to form the specifications for the size on the Dayton Drivers are? Finances are tight and I have a pair of Seas 27tdfc, and a Pair of Scanspeak HDS tweeters. I was thinking of using them to at least get things moving (ie. sizing for cutouts), and it looks like they are within 1mm of the Dayton drivers diameter and similarly in depth. I may just toss them in the cabinets to get these things fired up at the very least then order the RS28s when things settle down.

Any words of wisdom?

[JonMarsh]

My experience has been that the driver dimensioning from vendors like them (Dayton, Seas, Scanspeak) is quite accurate, so if it looks good on paper, you should be able to implement in practice.

[mischmat]

My experience has been that the driver dimensioning from vendors like them (Dayton, Seas, Scanspeak) is quite accurate, so if it looks good on paper, you should be able to implement in practice.

Thanks Jon. At least I can move forwards with them.

I'm kinda curious too how the sound will differ with the different tweeters. Wish I had measurement stuff, and new how to model it correctly.

[mischmat]

Progress

[mischmat]

More progress

[fbov]

One thing to consider when assembling your crossovers; they have to fit through the RS180 hole. That would have been a problem for my builds!
Frank

[mischmat]

One thing to consider when assembling your crossovers; they have to fit through the RS180 hole. That would have been a problem for my builds!
Frank

Yep, that's a concern. I still need to an inductor for the X/O, but my time is spent these days applying shellac. I'm trying my hand at French polishing so it'll be some time before I'm fully ready to test these babies out.

[TEK]

Would love to see some pictures from the process as well as the result...

[mischmat]

Here's the first installment of polishing. This is after the 4th application of shellac. Each applications consists of 9-10 passes with a drying time long enough that it is no longer tacky to the touch.

[TEK]

That's looking really great!

[mischmat]

1 Cabinet polishing complete. Just need to put in the terminals and dig some wood out of the tweeter hole so the tweeter fits in (bit shallow router couldn't go deep enough).

[BobEllis]

Nice job!

[TEK]

Very nice looking - looking forward to see how they are with all the drivers in :-)

[mischmat]

Quick question on L2. How close does the DCR need to be? I'm assuming the mH should be as close as possible, but unsure how the resistance affects the whole network.

[JonMarsh]

DCR of L2 affects the overall insertion loss (attenuation) and damping factor- up to about 0.25 ohms is OK (that's typical for an AWG14 air core inductor, but lower is better. The "ultimate" part would be something like the 500W Erse SuperQ inductors; but for that you'd have to buy a 1.5 mH and unwind it to 1.2 mH (presuming you have some kind of LCR meter). This DCR is a bit more critical for the NatP becuase it's a 4 ohm net speaker, so the DCR has double the impact it would for an 8 ohm design.

[mischmat]

I'd go that route if I could. Problem is I don't have an LCR meter to verify the mH, doubt a regular volt meter could measure. Off to google I go

[JonMarsh]

Amazon lists a number of budget LCR meters if you think that is something you'd like to add to your tool box.

[mischmat]

Amazon lists a number of budget LCR meters if you think that is something you'd like to add to your tool box.

If I played more with electronics I'd think about it but this is my 2nd DIY project in 4 years so I might as well just buy what I need at this point in time. What's your opinion on Janzten conductors, more specifically Jantzen 5004 1.2mH 15 AWG P-Core Inductor 255-102 at 0.140 ohm resistance it looks good to me. Better DCR than the Solen one I was looking at 0.240.

[mischmat]

About to pull the trigger on the P-Core for L2 from Janzten. Anybody have any concerns on using it in L2?

Upon further investigating, Ears has a 1.2mH SuperQ ESQ55-14-1200.

Just trying to keep costs down the equivalent solen would cost me close to $70 delivered.

[mischmat]

Journey Complete

All done.

[Mr.Ed]

Very Nice! And the sound?

[wkhanna]

yes! V nice!

[mischmat]

Very Nice! And the sound?

Haven't had much play time on them since I'm still waiting on some stands, but I'm extremely surprised on the bass output of these little guys. Never though I'd be shaking stuff on the walls.

They have a different sound than I'm used to though. I would have to describe it as neutral, in the sense that the highs aren't overly bright, and the bass isn't over powering. Everything is just there. You can pick out the details of instruments quite well. My go to test is Live - Lightning Crashes. There's a part in the chorus where the drummer goes from one cymbal to another that is very hard to hear, but with a keen ear and a good set of speakers you can hear it move from one speaker to the other. These reproduce it without issues.

Verdict? I'd build another set in a heart beat. Good job designing these Jon.