Sunflower HT/Music LCR Build

[WernerM]

Re: Sunflower HT/Music LCR Build

CROSSOVERS COMPLETED:

Stuffed boards and soldered 'em up. CC crossover installed, hope to get to the mains this week. Now comes the really hard part, resisting just throwing them together without the finishing/staining part done :eek: :D !!!

Very nice work. Keep it coming!!! Patience...Patience...PATIENCE!!!! LOL...:D

[donradick]

Re: Sunflower HT/Music LCR Build

Nice work! I, too, have these in my "dream" folder. The price is right, the size is right, but darn it,
my living room is not quite big enough.
Good work on the crossovers. I love those "euro style" terminal blocks.

[rvsixer]

Re: Sunflower HT/Music LCR Build

PORT LENGTH?

Need some help with port length for the main woofer box. Paul C has one of the tunings at 23Hz with an 8" port length. However, when I run the numbers, I come up with 10.4" (using Paul's measured RS225-8 parameters) .

Physical box volume: 41.2L
Driver/Vent volume: ~3L
Calculation box volume: 38.2L
Port: Precision Port 2" (adjustable from 4"-11")

I get 23Hz tuning at 10.4" port length. This differs quite a bit from 8", but 10.4" is close to the alignment in Curt C's article on small vented box alignments ( http://speakerdesignworks.com/Sealed_v_Vented.html ).

This recent post/links may shed some light as to why the specified vent length is quite a bit shorter than calculated:

http://techtalk.parts-express.com/showthread.php?232992-Bass-reflex-bass-bins-your-advice-re-acoustic-lining-please&p=1848027#post1848027

http://www.troelsgravesen.dk/vent_tuning.htm

In short, to qoute from the lower link:
"From this vent-tuning study is can be seen that calculating the vent dimensions is tricky business. From practical experience I have learned to multiply the vent length by 0.6-0,7 to get the targeted Fb. Quite some deviation from all the nice math..."

[rvsixer]

Re: Sunflower HT/Music LCR Build

DETAILS, DETAILS, DETAILS...
Bracing, wiring, lining, filling/sanding, stain selection/experimentation, final glue up :D .

Bracing:
After trying out three braces running from side to side, the mains woofer cabinets were still a bit too "thumpy" sounding during the knuckle test. So I hit google, and decided tieing all three axes together (and slightly stressing each outside surface) was the way I would go. Knock test sounds great now!

Crossover mounting, wiring:
Changing the bracing design of course messed up my intended crossover mounting location at the bottom of each mains cabinet :(. So after much experimentation, finally came up with a location that allowed getting the crossover in and out, as well as the addition/removal of lining later for tuning. Ran as much wiring as is possible before final assembly, labeling everything as I went.

Lining:
Paul C's recommendation of Walmart "wave" bed topper foam. I kept adding lining until a low spoken voice into the driver opening stopped "echoing", and just started to become "dead" sounding. Will adjust as necessary later.

Filling/sanding:
Upon Lou C recommendation here at PE, used Timbermate filler. Applies and sands great, will see how well it takes stain.

Stain selection/experimentation:
(EDIT: See revised staining picture posted further down in thread for correct stain sample photo) As mentioned before in the thread, I had preliminarily decided on CN preconditioner and General Finishes Java Gel Stain. I am a newbie stainer working with a blotchy wood, but this combination of products proved out to be great! Still deciding on the FLAT vs SATIN topcoat, see attached pic what do you think?

Final glue up:
I used PL Construction Adhesive to attach the mains baffles to the woofer boxes, per Bill F recommendation for its superior gap filling properties. On the Sunflowers, as I have constructed the cabinets, this was a largely "blind" operation. I had to use something that I had confidence in would fill any and all gaps.

[WernerM]

Re: Sunflower HT/Music LCR Build

I'd go with the satin as to me it makes the grain pop a little more. Looking very nice BTW. Can't wait to read your "final impressions" review! :D

[DIYNut42]

Re: Sunflower HT/Music LCR Build

Looking great as usual! I like that you're taking the time to put your own personal touches into it. Like the extra bracing. I doubt that amount of bracing will take up enough volume to change the tuning by that much.

As far as lining the woofer enclosure, you might want to take a page from the statements build and put some insulation on the back panel for experimentations sake. Especially since the statements use the same 8" woofer as the sunflowers do. If it seems overstuffed you can always remove it.

Did you ever decide if you're going to try to make a grill using grill cloth for the back of the MGM section?

[rvsixer]

Re: Sunflower HT/Music LCR Build

I'd go with the satin as to me it makes the grain pop a little more. Looking very nice BTW. Can't wait to read your "final impressions" review! :D

Thanks for the compliment! By mistake I clearcoated the two stain coat sample, not the three stain coat sample. The three coats of stain looks and "pops" much better, as soon as the flat and satin clearcoat is dry I will repost the pic.

[rvsixer]

Re: Sunflower HT/Music LCR Build

Looking great as usual! I like that you're taking the time to put your own personal touches into it. Like the extra bracing. I doubt that amount of bracing will take up enough volume to change the tuning by that much.

As far as lining the woofer enclosure, you might want to take a page from the statements build and put some insulation on the back panel for experimentations sake. Especially since the statements use the same 8" woofer as the sunflowers do. If it seems overstuffed you can always remove it.

Did you ever decide if you're going to try to make a grill using grill cloth for the back of the MGM section?

Thanks Ryan!

The cabinet is already about 2-3 liters larger than the original design, so even with the extra bracing I am still on the + side. Thanks for the bit on the statements insulation. The center channel will be stuffed with fiberglass, I can certainly try some in the mains as well.

Werner was the wrap around grill guy . I myself don't like grills at all, I like my speakers as naked as possible :D. In fact if my small multipurpose room could handle it I would have 18" H-frame OB bass, but that's were the Sunflowers stepped in. Dipole mid's, but bass in a much narrower package that better fits my space (and the reason I am bracing to the hilt and tuning the lining to avoid coloration as best as possible). It's all about tradeoffs...

[rvsixer]

Re: Sunflower HT/Music LCR Build

Okay here is the correct stain sample (three coats gel stain, three coats of flat & satin topcoat). As you can see compared to the two coat photo previously posted, the third coat really helps even the color out and makes things "pop". Unanimous vote from myself, my wife, and coworkers is the flat topcoat is better overall. The satin definitely "pops" more, but shows imperfections more readily and the flow out seems less even/uniform.

[WernerM]

Re: Sunflower HT/Music LCR Build

Okay here is the correct stain sample (three coats gel stain, three coats of flat & satin topcoat). As you can see compared to the two coat photo previously posted, the third coat really helps even the color out and makes things "pop". Unanimous vote from myself, my wife, and coworkers is the flat topcoat is better overall. The satin definitely "pops" more, but shows imperfections more readily and the flow out seems less even/uniform.

Now with the corrected sample, I would agree with the flat, the satin is almost to "shiny" to me.

[scottq]

Re: Sunflower HT/Music LCR Build

Looking great! Thanks for keeping us up to date

[fastbike1]

Re: Sunflower HT/Music LCR Build

Sorry, but I think you've got something going on in your finish. Birch has no real grain and not much figure and should be essentially smooth. You shouldn't have the striations / linear marks that are shown in the photo.

[rvsixer]

Re: Sunflower HT/Music LCR Build

Sorry, but I think you've got something going on in your finish. Birch has no real grain and not much figure and should be essentially smooth. You shouldn't have the striations / linear marks that are shown in the photo.

And I was all ready to start staining tonight!

The picture was intentionally taken to maximize reflection, to show the glare difference flat vs. satin finish. If viewed without reflection, the surface appears no rougher than the 150 grit pre-stain sanding treatment, and is very uniform looking. Also, I can readily see grain direction/patterns in the bare birch I used?

Please elaborate, thanks. I don't need the last step (finishing) to turn into disaster :eek: !

[WernerM]

Re: Sunflower HT/Music LCR Build

I think what Fastbike is talking about is the etched (scratched) look of grain in the picture you last posted. What technique did you use to apply the stain?

[rvsixer]

Re: Sunflower HT/Music LCR Build

I tried several methods to apply the stain, I had the best luck with plain old socks. Gel stain is weird stuff, imagine (literally) wiping on chocolate pudding.

While pre-conditioning the cabinets last night, I determined what is showing in the pics is the wood surface. Even though I sanded with the called out for 150 grit, the surface has the etched/scratched look, which is then coming through in the pics (and its over exaggerated in them).

The surface is now actually rougher now due to the grain raising after the pre-conditioner. I am wondering if I should just knock everything down to 220 grit, and then apply a light coat of pre-conditioner to replace what I remove during the process?