Thoughts on RS-150 TL designs?

[patrickm]

I've been intrigued with the Copper Project since I saw the latest catalog, and i've done a couple pairs of the Cyburgs Needles in the past and was pretty impressed with their performance, so i've been wondering if there might be a Copper-like design that makes sense with a couple extra RS150-4's I have sitting around. these will not be for high-volume use, and will probably end up in a living room as a stereo pair w/o a sub, so i was looking to maximize low frequency extension even if it costs me a few db of sensitivity.

I have the old TL mathcad sheets from when I first built the tweaked B3N needles a while back, and it seems like a bit of an improvement over just using a large ported tower, but I was looking for some feedback from Paul K and a few of the more experienced TL designers to see if they think it's worth doing with that driver, or if there are some possible optimizations I'm overlooking. Here's a first cut at what I've been considering:

TM with RS-150 and some tweeter I have around, possibly the Vifa BC25SC06's -- which work pretty well with the shielded RS150-8, and a crossover somewhere around the 2.6-2.9k range.

TL parameters:
line length ~ 68in
ratio 15:1 (Sclosed=.2 Sd, Sopen=3Sd) (interior dim's ~ 6"x7")
Vb~ .85 ft^3
tuning ~ 37hz (2" x 5.25" port)
driver is roughly at the midpoint of the line.

the modeled response, not factoring BSC (since the older sheets don't) is below. any thoughts or constructive criticism appreciated. (the RS-150 specs i used were from the PE PDF datasheet)

thanks

[Paul K.]

What you've done looks pretty good, actually, assuming you want that gradual droop in the response curve for some reason, like to match up with your room's "gain" at lower frequencies. If I were doing this, I'd raise the system tuning frequency (shorten the line, for instance) and make the response be flat down to the knee in the curve, and if I then wanted a lower F3, I'd simply increase the volume in the line (assuming a bigger box would be acceptable).
Paul

[patrickm]

thanks paul -- appreciate the feedback. i'll run a few more numbers and see what tradeoffs seem to be the best compromise. i think a bit deeper box, and maybe a couple inches taller would still work.

for anyone else that's interested, i modeled a few crossovers. no measurements yet, since i haven't built the enclosure, but hopefully next weekend.

three different versions. i'm more partial to the first, with the 2.5k xover point and the lower part count, but i'm not sure how well the tweeter will handle it. the second version has a higher xover point 3.1k, but phase matches up a lot better through the crossover region. this turned out to be a bit trickier than i thought because of where the breakup node for the RS150 is and the 4/5khz peak/dip combo on the vifa tweeter.

one dips to 3.9 ohms and the other at 4.0, but are otherwise 4-ohm friendly.

[patrickm]

finally got these finished this weekend. they turned out very well. i think they're a good floorstanding budget option- i think they come in around $150 for the pair, plus cabinets. except for the 1/2" MDF divider, i built these out of 3/4" pine, but stain hasn't been decided yet. the pine worked fine, and i added a brace or two made from 3/4" dowel through the divider just to be safe. the bottom has about 1.5" filled with sand, and the tweeter compartment is separated to keep the TL geometry as intact as possible.

the bass is substantially deeper than the vented MT i built this winter with the RS-150S-8, using the same tweeter.

i built the 3k crossover version first and went with the better phase tracking, though i did up the first inductor to .95 mH to up the baffle step, and that lowered the final crossover point a tad. i'll post some better photos and a complete parts list in the gallery forum soon.

thanks especially to paul k for looking over the initial design, and marty's copper project for inspiration.

here are a few lousy photos from a cell phone:

[fastbike1]

Come on, now that the build is done, we need a little more. How about cab details? Which crossover do you decide on? Thanks.

[patrickm]

Come on, now that the build is done, we need a little more. How about cab details? Which crossover do you decide on? Thanks.

easy now... i said i picked the 3k crossover, and changed the inductor to .95 mH. the cabinet is 7.5"w x 9"d x 40" h, though as i mentioned, the tweeter is separate and the bottom has a sand compartment. the interior is about 35.5" for the main chamber. port is 2"x4.25", or thereabouts. there's about 8-10oz of stuffing in each, getting progressively lighter towards the open end, for about a 1 lb/ft3 density.

[joeybutts]

Hey Patrick, hopefully you see this, if not I'll pm.

I ordered the list of crossover parts in the other thread.....

QUOTE:

1.0 mH coil
.25 mH coil
.20 mH coil
8ohm 10W resistor
25ohm 10W resistor (4)
1.5uF poly
4.7uF poly
6.8uF poly
10uF poly

But I don't see a crossover schematic that uses these parts (unless I am totally missing it.). Thanks for any clarification! Cabinets are just about ready for the baffle to go on, just need the crossover and the finish! EXCITEDDDDDDDDDDDDDDDD

[patrickm]

if you have the 4-ohm RS150-4, check the top post in this thread.

if you have the 8-ohm, the crossover in is this thread on the RS150s-8 version, originally the M/T bookshelf in my signature. http://techtalk.parts-express.com/sh...6-Bookshelf-MT