RS-150S / Vifa BC25SC06 Bookshelf MT

[patrickm]

this was a project for a friend. shielded 8 ohm RS150 plus vifa fabric neo tweeter. Total cost came in around $130 for the pair, plus wood. cabinets are 3/4" pine all around. there's egg crate on the sides and a wad of dacron stuffing. dimensions are 7.5" w x 11.5" h x 10.25"d, vented to about 48hz. they were intended to be used with a 12" RSS HF sub.

These can also be built in the TL cabinet used for the RS150-4 MT in my signature, a full writeup of Ed's build can be found in this thread. personally, i think the 8-ohm design came out smoother than the 4-ohm.

[bigbardmusiq]

I bet they sound good, what kinda finish you gonna put on them?

[patrickm]

they were made as a gift, so the finish will be whatever my friend decides. they are pretty nice. the TL version is even better.

[gowa]

Nice job!

[AudioSQ]

I'm interested in building this design for my brother. He wants a good MT for around 140 bucks using a 6"ish. Can you tell me more about your listening impressions and the cross over build? Pardon my ignorance but what exactly does "the TL version" mean and why is it better? Thanks! Looks good!

Bruce

[patrickm]

hey - thanks for the compliments. The crossover isn't too hard to build, especially if you think of it as a bunch of sub-assemblies. part of what my friend wanted was to learn about how speakers work, so i drew the crossover up as a set of elements. for the big inductor on the woofer, i used a P-core, for the others, i used 18ga or 20ga air core. the resistors were all daytons. the capacitors can be either the dayton poly's, though the one on the woofer lowpass can be electrolytic to save you a few bucks. The port is the PE 1.5" flared one that's only a few bucks.

The TL version is the transmission line floorstander. I used the RS-150-4 (unshielded, 4 ohm) version for that because i had it around. The bass is much deeper, and the only real extra expense is the larger cabinet. the crossover is a little different with the -4 than the -8 ohm version, but the tweeter is the same. i will put up a post for that by itself with all the crossover details when i get them off the other computer. if he's not going to use a sub and can run a nominal 4-ohm speaker on his amp, i'd definitely go that route. they're about 36" tall, though i added a couple extra inches to fill with sand as a ballast at the bottom. here are a few photos of them when i was building and when i had them set up for testing:

both have a relaxed sound to them, probably similar to LouC's C-killas (which use the dayton ND28FA tweeter but are a very similar overall design to the bookshelf version). The bass for the TL's is surprising. you could probably squeeze out a little more low end from the bookshelf with a slightly larger cabinet, but there's always a tradeoff...

[J.Lee]

I like the use of pine. Do you have a reason why?

" Godzilla" over at DIY is stuck on the stuff - claim's it gives a 'warmer' tone than MDF or Baltic Birch.

Let us know what your friend decides for a finish. I've done furniture with pine in the past and always ended up with a reddish tint I didn't like.

Nice design.

[patrickm]

I like the use of pine. Do you have a reason why?

" Godzilla" over at DIY is stuck on the stuff - claim's it gives a 'warmer' tone than MDF or Baltic Birch.

Let us know what your friend decides for a finish. I've done furniture with pine in the past and always ended up with a reddish tint I didn't like.

Nice design.

thanks, man. main reason in both cases here was aesthetic. it probably does give a warmer tone because it's not as acoustically dead as denser materials. it's not as expensive as a lot of hardwoods, and as far as looks go, it's also not too hard to get panels with some interesting grain that don't need planing and that match up color-wise over time, and i was also building furniture in addition to speakers (bookshelves, entertainment center, dvd shelves, speaker stands, cabinet). finding big panels (or making them with a biscuit jointer) would be really expensive or time consuming, and i wouldn't want to try and veneer all that stuff.

i do usually go with some extra bracing... in the TL, there are actually one or two braces that run through the center divider because the sides seemed to vibrate too much. i just drilled a slanted hole through it, and used urethane glue on both sides and the middle. the TL's will probably get a very light colored, almost yellowish stain, so the tint is an advantage there.

[fastbike1]

I would also be interested in seeing the XO and cab details for the TL if you get the time. Definitely nice work.

[J.Lee]

Thanks Patrick -

I like your Audio cabinet as well.

Can you tell me where you got your pine at and what sizes it's available in?

[patrickm]

Can you tell me where you got your pine at and what sizes it's available in?

i actually got most of that at home depot, in the shelving aisle as pre-sanded, clear-laminate wood shelving. i have noticed recently that they've been shifting from true 3/4" (.75") thick panels to .656, which while only about 10% thinner, don't seem nearly as solid. and just check the edges, at the closest store to me they have it on a wire rack bottom, and some get chewed up. the smaller shelves usually lay flat, so you can tell which ones are warped. they also have 48x11.5" MDF shelving there too for people that can't move full sheets around.

they sell a number of really useful sizes for speaker building, from 36" x 11.5" (nominal, sometimes they're 11.75 or 11.25 in different stores), 48"x11.5", up to 48"x23" and 72" x 24". it's a little more expensive than the regular pine lumber, but they're planed and finished to a sharp edge, so it saves a lot of work. they're hard to find on the website, but search ".656" to find the larger panels. looks like the 3'x1' and 4'x1' shelves are still .75".
http://www.homedepot.com/webapp/wcs/...atalogId=10053

they also sell some lightweight "generic hardwood" edge-glued panels. These seem much less dense than the pine but are stiffer. i haven't made any speakers out of them, but color-wise, they're better for darker stains, and I have used one for a tv shelf to match some darker stuff we have in the house.

[patrickm]

I would also be interested in seeing the XO and cab details for the TL if you get the time. Definitely nice work.

no problem. i'll get it posted this weekend, probably in its own thread. i think there's preliminary crossover and cabinet dimensions on the techtalk board from a month or two ago. (edit: here's the thread)
http://techtalk.parts-express.com/sh...d.php?t=217244

i have the preliminary parts list from pricing it out in my PE cart.
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

i think the L-pad is an 8-ohm and a 12.5-ohm, and the notch filter on the woofer had a 40-ohm, but it's actually cheaper to buy all 25-ohm's and use parallel and series to get 12.5 and 50, respectively. using 30, 40, and 50 ohms in the notch filter makes a minor difference, but nothing that was really apparent to me in listening tests.

it uses the RS150-4 (unshielded) and the same Vifa BC25SC06 tweeter as the bookshelf. with those crossover parts and the $3.50 rectangular 5-way binding post terminal plate, it totals $149 in parts with an air-core on the big inductor and $160 with p-core (which saves about a dB in woofer output).

[J.Lee]

Thanks Patrick -

We've got a Home Depot near.

[johnnyrichards]

See, my dad always said "I don't need anything fancy for my carcass, pine is fine"... So these could be a neat little "coffin" speaker

They look nice, Patrick. Good work.

[joeybutts]

no problem. i'll get it posted this weekend, probably in its own thread. i think there's preliminary crossover and cabinet dimensions on the techtalk board from a month or two ago. (edit: here's the thread)
http://techtalk.parts-express.com/sh...d.php?t=217244

i have the preliminary parts list from pricing it out in my PE cart.
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

i think the L-pad is an 8-ohm and a 12.5-ohm, and the notch filter on the woofer had a 40-ohm, but it's actually cheaper to buy all 25-ohm's and use parallel and series to get 12.5 and 50, respectively. using 30, 40, and 50 ohms in the notch filter makes a minor difference, but nothing that was really apparent to me in listening tests.

it uses the RS150-4 (unshielded) and the same Vifa BC25SC06 tweeter as the bookshelf. with those crossover parts and the $3.50 rectangular 5-way binding post terminal plate, it totals $149 in parts with an air-core on the big inductor and $160 with p-core (which saves about a dB in woofer output).

Patrick, (or anyone with the knowledge), is the 8 ohm RS150 a direct drop in replacement with this crossover? I couldn't tell after reading through the three threads related to this design. Thanks!!

[patrickm]

Patrick, (or anyone with the knowledge), is the 8 ohm RS150 a direct drop in replacement with this crossover? I couldn't tell after reading through the three threads related to this design. Thanks!!

Hey Joey - i have not tried it myself, but from everything I've seen from others' testing, it should be extremely close. I plan to eventually swap the prototype into my TL's in my living room that I used the RS150-4 for because this one just sounds better - possibly the best crossover i've done, and see if i can't do some tweaking on the -4 to make it sound as good. The TL cabinets were close enough that it should basically be a drop-in.

[joeybutts]

Well, if it is that close, I'll just go for it since these are only going in the garage anyway. I think Ed used an 8 ohm in his too....

[joeybutts]

Well, if it is that close, I'll just go for it since these are only going in the garage anyway. I think Ed used an 8 ohm in his too....

Also, I noticed Ed's have the tweeter offset and yours are centered. Any difference there?

And I hope my last three questions, , what are the dimensions of the cabinet? I saw the post that said 7.5Wx9Dx40H and that the internal chamber is about 35.5". So WITHOUT the tweeter compartment, just the TL part, it has 37" of height with 3/4" material all around? And how long is the divider?

And how did you seal the port to the divider in the TL? just caulk/pl adhesive/epoxy?

[bungelow_ed]

I don't know how I missed this thread when it started....must have been the good weather. Yes, I used a RS150S-8.

[patrickm]

Also, I noticed Ed's have the tweeter offset and yours are centered. Any difference there?

mine probably have a slightly worse diffraction signature than his, but symmetry was a requirement for me to get them into the living room.

And I hope my last three questions, , what are the dimensions of the cabinet? I saw the post that said 7.5Wx9Dx40H and that the internal chamber is about 35.5". So WITHOUT the tweeter compartment, just the TL part, it has 37" of height with 3/4" material all around? And how long is the divider?

yes, 37" tall exterior with 3/4 material for just the woofer/TL section. i believe the rest of the panels were actually 0.656" instead of true 3/4" because of the stock i had on hand. Instead of adding 1.5" for your stock, add 1 5/16" for mine.

interior dimensions would be 6 3/16" W x 7 11/16" D. with 3/4", these would end up as exterior dimensions:

7 11/16" W * 9 3/16" D

And how did you seal the port to the divider in the TL? just caulk/pl adhesive/epoxy?

i didn't. check the link here:
TL photos from 4-ohm version

and there's a photo towards the bottom. when you're looking at the baffle, you're looking at the divider edge-on. i don't have a measurement written down, but you want it to be about equidistant from the three sides of the cabinet (paul k's useful suggestion was to shade this a little towards the shorter end, so that as air would move through it from small to large end, would be a generally increasing cross sectional area, even if it really wasn't linear right around the driver. mine was glued already at that point, but maybe 1/4" offset would be enough)

on my nano neo mini-towers and on this one, i put some braces through the divider from side to side. spade bit through at an angle that keeps the dowel brace horizontal, then epoxy or urethane adhesive where it goes through the divider.