on Sale - $55/pr (drivers & XO)

[fastbike1]

Re: on Sale - $55/pr (drivers & XO)

I'm not trying to belabor this but you seem really frustrated. The quoted port length is what Chris used to get the tuning he wanted. If you want to consider that ideal, ok. However, you seem to be missing the point that the one inch variance doesn't affect the actual box response that much. I think you should be much more concerned about port velocity.

For Ericj, That's normal. PVC pipe is sized by nominal diameter, same as wood (i.e. nominal dimensions).
It behooves a guy to head to his home improvement store and measure the actual ID of the various choices so that he/you can model more accurately.

Also don't forget to go through the electrical section as well. PVC conduit is available in sizes that you don't find in the piping area (e.g. 2.5", 3.5", etc). The extra 1/2 inch gives you a lot more tuning flexibility.

This I understand perfectly. I've built numerous subwoofer boxes before and played with WinISD till I was blue in the face, but I was more referring to what is recommended as the ideal port length for this specific application; the NTN cabinets. I don't want to tune them too low or too high, and I believe the 39hz tune was the ideal, but when I run those numbers I come up with a 8.46" port, while the recommended port size on page 2 that Chris came up with was 7.09 for that same frequency. I'm just trying to figure out which one to use.

[Chris Roemer]

Re: on Sale - $55/pr (drivers & XO)

A year ago, when I first designed the NanoNeos, I used my (then) new WT3 to run T/S parms on a pair of ND20 tweeters, and my ND105-4 woofers. I only had a sample of 2 drivers in each case.

You hear "tolerance" numbers bandied about quite a bit. Supposedly, morre expensive drivers (Scan, Seas, morel) have tighter tolerances (open for debate, I'm sure). +/-10% seems to be in the ballpark.

Last year, my sample of 2 woofers (luckily, or unluckily) BOTH fell on the end of the window leading me to shoot for a slightly larger box with lower tuning. THIS year I tested 8 woofers. While I DID have one woofer that fell midway between my 2 samples from last year, MOST had slightly higher Fs values than last year. Looking at the new T/S parms made me feel as though a slightly smaller box w/slightly higher tuning couldn't hurt.

Sooner or later I'm going to change my box drawing to reflect the 0.28 cf box (the one that can fit all 12 panels on one 24"x 48" sheet of stock. The ntns are exactly twice the size, or 0.56 cf. To keep the same tuning on a box that's twice the size, you CAN use a PAIR of 1.5"d ports the same length as those on the NNs, OR you can use a single port (the same length) with twice the area, which (for all practical purposes) is a 2"d port. A 7" long vent works pretty good for either design.

On my 1st 0.30 cf NN box, (but looking at my revised T/S parms from this year) the tuning (which almost looked like a EBS alignment) could have used a slight "lift" to keep it from hollowing out. A SLIGHTLY smaller box can help out here, so can a slightly higher tuning (shorter vent), SO can a slightly higher DCR on the woofers series coil. You can see all these things reflected in my posts and in any upcoming "revisions" (which are really updates to better reflect what I've advising people all along).

Chris

[XtremeRevolution]

Re: on Sale - $55/pr (drivers & XO)

Chris,

Thanks for that update.

The truth is that I had already cut these to 7-1/8" and I had the other length of pipe from the kit which I could have cut longer if need be. Looks like I don't have to do any more work on the ports.

[XtremeRevolution]

Re: on Sale - $55/pr (drivers & XO)

I'm not trying to belabor this but you seem really frustrated. The quoted port length is what Chris used to get the tuning he wanted. If you want to consider that ideal, ok. However, you seem to be missing the point that the one inch variance doesn't affect the actual box response that much. I think you should be much more concerned about port velocity.

My concern for port velocity is what led me to buy the huge flared ports instead of using PVC.

[ericJ]

Re: on Sale - $55/pr (drivers & XO)

I got the same deal at HD (did you buy yours based on my recommendation or was it just a coincidence?). I'm guessing the difference in diameter isn't critical, especially for the fidelity of these little speakers.

As for the port length, Chris calls for a total port length of 8" in the original plans, which for a wall thickness of 3/4" makes it a 7.25" long tube. A 1/4" here or there won't make a difference, really, so whoever is using a 7" tube should be fine.

Based on your recommendation, thanks!

Now I need to find a good way to mount this port. I don't have a plunge router to make a rebate in the rear of the baffle, like many do. I have used scrap MDF with a hole the size of the OD of the port. Slip the port in and glue. Then I glue that all to the rear of the baffle. I then cut out the id of the tube and used the flush trim and roundover. I'm concerned that method with this speaker may take up even more volume. Maybe not.......

[Drew_V]

Re: on Sale - $55/pr (drivers & XO)

Based on your recommendation, thanks!

Now I need to find a good way to mount this port. I don't have a plunge router to make a rebate in the rear of the baffle, like many do. I have used scrap MDF with a hole the size of the OD of the port. Slip the port in and glue. Then I glue that all to the rear of the baffle. I then cut out the id of the tube and used the flush trim and roundover. I'm concerned that method with this speaker may take up even more volume. Maybe not.......

Considering that the designer is looking to REDUCE the recommended cabinet volume slightly, I wouldn't worry about the small scrap piece that you glued around the PVC tube for strength. That should be just fine.

Another option (which I am going to do) is just to glue the internal cabinet brace to the PVC tube as well using epoxy. It should be more than strong enough.

[Herman Trivilino]

My ntn xover

Here's a shot of the xovers and drivers for my ntn's. This is just an audition to make sure everything is working ok, and it gives me a chance to break in the drivers. I just left them on one day out in the garage, while I was away at work.

These are the ntn's Chris described back in Post #18, with one change. He recommended replacing the 6 ohm resistor in the Zobel with a 20 ohm, so that's what I did. I've done a bit of lay-out work on the baffles, but oitherwise plan to start on the cabinets next week.

[XtremeRevolution]

Re: on Sale - $55/pr (drivers & XO)

Progress is slow but steady.

[ericJ]

Re: on Sale - $55/pr (drivers & XO)

Looking good Herman T. Those ports are gargantuan!
So, it's down firing, right?

[XtremeRevolution]

Re: on Sale - $55/pr (drivers & XO)

Looking good Herman T. Those ports are gargantuan!
So, it's down firing, right?

That's right, down firing. The actual length of the port assembly is 8.125", but the 2" ID length of the port itself is only 7.125". and yeah, they are very large ports. Should basically eliminate port noise.

[cwad8505]

Re: on Sale - $55/pr (drivers & XO)

This thread has become HUGE ... and rightfully so!! I purchased the parts for the nn's a few weeks back but have now decided to do the ntn's. I realize the info is in here somewhere, but could someone (Chris maybe?) tell me what post has the lastest and greatest parts list for the ntn's? I realize the schematic is in Chris's profile, but was hoping to speed the process slightly.. any help here would be appreciated! Thank you - Chris W..

[Herman Trivilino]

Re: on Sale - $55/pr (drivers & XO)

This thread has become HUGE ... and rightfully so!! I purchased the parts for the nn's a few weeks back but have now decided to do the ntn's. I realize the info is in here somewhere, but could someone (Chris maybe?) tell me what post has the lastest and greatest parts list for the ntn's? I realize the schematic is in Chris's profile, but was hoping to speed the process slightly.. any help here would be appreciated! Thank you - Chris W..

There may be a parts list back there in one of those messages, but you'd have to check it against the schematic anyway to make sure it's right. My ntn's make use of the older version of the xover (different from the one in Chris's profile) so my parts list wouldn't do you any good.

By the way, IIRC, I checked the price of the woofer the other day and noticed it's no longer on sale.

[cwad8505]

Re: on Sale - $55/pr (drivers & XO)

There may be a parts list back there in one of those messages, but you'd have to check it against the schematic anyway to make sure it's right. My ntn's make use of the older version of the xover (different from the one in Chris's profile) so my parts list wouldn't do you any good.

By the way, IIRC, I checked the price of the woofer the other day and noticed it's no longer on sale.

I think I just found it.. and I realize the driver is no longer on sale.. which really stinks!!! Think I might just leave the parts that I have in the box and wait for them to go back on sale or see if someone wants to sell their extras (hint hint to those viewing :D ) Thanks for the quick response Herman! Chris

[Drew_V]

Re: on Sale - $55/pr (drivers & XO)

I think I just found it.. and I realize the driver is no longer on sale.. which really stinks!!! Think I might just leave the parts that I have in the box and wait for them to go back on sale or see if someone wants to sell their extras (hint hint to those viewing :D ) Thanks for the quick response Herman! Chris

I wonder if it would be worthwhile for someone to look into this driver as a substitute:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=297-434

I have absolutely no clue about whether it would work or not, I just saw that the HiVi was only a couple dollars more than the Neos and had good ratings.

[Chris Roemer]

Re: on Sale - $55/pr (drivers & XO)

I think I just found it.. and I realize the driver is no longer on sale.. which really stinks!!! Think I might just leave the parts that I have in the box and wait for them to go back on sale or see if someone wants to sell their extras (hint hint to those viewing :D ) Thanks for the quick response Herman! Chris

Actually, I was under the impression that Herman had some spare parts (at least some coils?) that he measured/modified in his lab, and therefore has more of a "one-off" crossover.

2 of each required (4 woofs of course)
HP:
027-425 5.6uF pp cap
255-026 0.25mH #20 coil
015-4 4 ohm 5w resistor (10w OK)
015-2 2 ohm 5w resistor (10w OK)
275-030 ND20FA-6 tweeter

LP:
266-554 2.0mH "I-core" inductor
027-324 2.2uF npe cap (poly fine if you'd prefer)
016-20 20 ohm 10w resistor (10w required here)
027-336 6.8uF npe cap
290-212 ND105-4 woofer

+ ports, boxes (be sure to use 3/4" material), lining, terminals, wire, . . .

Chris