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Old 13th August 2007, 01:16 AM   #1
gychang is offline gychang  United States
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Default 8" Pioneer, build, the Chang variant

Dave and Scott have been a tremendous inspiration for a novice like me to build these fantastic projects.

My constant pestering around here have actually resulted in the Chang spawn. Specifically designed with the Pioneer B20FU20-51FW, and of course with my name on it, I had to build it...

Lots of work to do yet, will be putting finishing touch on the brace, put on edge veneering, finishing with poyurethane without stain, and also will be reinforcing the driver frame with the epoxy.

I finally figured out how to upload pics from photobucket. Can I get by using the heavy carpet on the top/bottom of the main cabinet?, I have polyfil but is in the pillow and not layered, and find it ackward to use on the top...

Any help on the sound damping will be appreciated.

gychang

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Old 13th August 2007, 01:24 AM   #2
gychang is offline gychang  United States
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one more.

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latest as of sunday PM.

gychang
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Old 13th August 2007, 01:45 AM   #3
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That looks SOOOO GREAT! And its not even that tall at around 63 inches. I may have to build it too! But let me ask a question: can i build it half height with only the opening at the bottom? I am not sure how these double horns work but wonder if building only half of the design would result in a well designed speaker... or does it have to have both horns top and bottom to sound best?

What will you be using for a tweetah? I always liked the cheap piezo with the B20 but i'm sure there are many other different flavors that will work well.

Godzilla
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Old 13th August 2007, 02:14 AM   #4
gychang is offline gychang  United States
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Quote:
Originally posted by Godzilla
That looks SOOOO GREAT! .. or does it have to have both horns top and bottom to sound best?

What will you be using for a tweetah? I always liked the cheap piezo with the B20 but i'm sure there are many other different flavors that will work well.

Godzilla
Godzilla: I am anticipating a great sound from the classic 8" Pioneer. Scott have designed double horn and not sure what effect it will have just with one horn.

I have been told by a reliable source, a tweeter from partsexpress

http://www.partsexpress.com/pe/pshow...TOKEN=83033797

will work well with 4uf capacitor on + side of the tweeter, that will result in crossing at 5KHz. when used with the Pioneer. No other crossover needed.

Is this correct?, I plan to try it later if I need more sparkle...

gychang
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Old 13th August 2007, 02:51 AM   #5
OzMikeH is offline OzMikeH  Australia
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Default Re: 8" Pioneer, build, the Chang variant

Quote:
Originally posted by gychang

Any help on the sound damping will be appreciated.

gychang
staple gun helps stick the polyfill in place. set it gentle so they only go halfway in.
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Old 13th August 2007, 03:09 AM   #6
gychang is offline gychang  United States
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Default Re: Re: 8" Pioneer, build, the Chang variant

Quote:
Originally posted by OzMikeH


staple gun helps stick the polyfill in place. set it gentle so they only go halfway in.

thanks, will try it.

gychang
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Old 13th August 2007, 05:07 AM   #7
OzMikeH is offline OzMikeH  Australia
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I just noticed your back panel is 276 wide. Any particular reason you went this way instead of 240mm?

Are your sides 310 wide?
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Old 13th August 2007, 08:45 AM   #8
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I would assume he used a full width back-panel with the side panels attached to the front face. Going to a width of 310mm with internal 276 would of course result in a completely different cabinet design. Lovely work BTW Greg.

Jeff, yes, there's no reason why a version of this couldn't be done with a single flared vent rather than the doubled ones. The back-chamber would remain constant, it'd just need the vent retuning / sizing to work. I'll look into it when I get chance if you like. Greg is building to the v1.0 design. The v1.1 plans have a concave front designed for them by Ron, which loads the driver front & rear & provides an optimal wavefront -see attached render by Marce, (Marc, who only lives about 50 miles from where I'm based), who's planning on building a pair soon.
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Old 13th August 2007, 09:39 AM   #9
OzMikeH is offline OzMikeH  Australia
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I was talking about the sides being 310, I should have said deep not wide.

I'm building a pair too, I'll start in about 2 weeks. The curved front put the WAF through the roof so they beat the Bruce.
I'll make it with chopped corners - no voids. I will need a leg or something at the back to stand it up which will be a good place to conceal the wiring and connector. I might even lean them back a bit. I want to join the top, diagonals, back and bottom all with 22.5 degree cuts so the wood matches up nicely at the 45 degree intersections.

I need to figure out how to make the horn flare for the backmounted tweeter. It's looking like an unpleasant couple of days with the rasp and sandpaper at this stage.

I hope Greg doesn't mind me freeloading in his thread, this is his build after all.

It will be interesting to see where the Chang fits in the Frugal family tree. Calhoun's mutant half-brother the heart of a Pioneer and super powers from the gamma rays leaking out from under Ron's hat, able to leap tall wallets in a single bound... Man, I need more sleep.
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Old 13th August 2007, 11:44 AM   #10
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The Spawn range is going to come in for a bit of reorganising over the next month or so. These boxes are the direction the BVRs are now going in, though the legacy types will probably continue for those who like the aesthetics. I'll work on it when I get time. I need to get the dimensions over to Dave & Ron later today actually for the smaller two boxes.
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Old 13th August 2007, 11:50 AM   #11
gychang is offline gychang  United States
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Quote:
Originally posted by OzMikeH
I was talking about the sides being 310, I should have said deep not wide.

I'm building a pair too, I'll start in about 2 weeks. The curved front put the WAF through the roof so they beat the Bruce.

It will be interesting to see where the Chang fits in the Frugal family tree. Calhoun's mutant half-brother the heart of a Pioneer and super powers from the gamma rays leaking out from under Ron's hat, able to leap tall wallets in a single bound... Man, I need more sleep.
I followed the dimensions put up by Scott and Dave on the original Chang plan, I used the sides at 310mm deep. Ron's idea of curve appeal is indeed an additional twist.

I am hopeful the Chang makes it into the family tree. Simplicity of the build is very attractive to start with.

gychang
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Old 13th August 2007, 11:57 AM   #12
ronc is offline ronc  United States
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Pioneer and super powers from the gamma rays leaking out from under Ron's hat


Gee, i hope not!

All the effect is simply a focused array with a single driver at a given BW.

ron
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Old 13th August 2007, 12:24 PM   #13
OzMikeH is offline OzMikeH  Australia
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Quote:
Originally posted by gychang

I am hopeful the Chang makes it into the family tree. Simplicity of the build is very attractive to start with.

gychang
A weary attempt at humour Ron, You have to admint it does more than it appears to at first glance.

I was all psyched up for complicated cuts in the Bruce, then this comes along with such a simple, smart design. Fortunately it's very flexible so I can still make life hard for myself.
Someone used the work synergistic for one of the earlier variants - this is even more so with the mouth integration.
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Old 13th August 2007, 01:28 PM   #14
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Default Stuffing Matereial

Not sure if you will be able to find it, but, there is a new type off stuffing I ran into. It is rolled furnace filter. Generally used in industrial or building maintenance. The roll found is about 1" thick. This stuffing looks like it would breath better than acoustistuff, or foam, and would layer more evenly than polyfill. Not sure where to start looking for it, but would try the hardware store first. It may be expensive, but so far, minor testing, it works well. The material reminds me of a cross between the fiberglass blankets and sponge-ish cotton.

Beautifull box by the way
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Old 13th August 2007, 01:36 PM   #15
gychang is offline gychang  United States
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Default Re: Stuffing Matereial

Quote:
Originally posted by zayne742
It is rolled furnace filter. Generally used in industrial or building maintenance. The roll found is about 1" thick.

brand name by any chance?

gychang
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Old 13th August 2007, 01:42 PM   #16
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Will find out, but in the meantime.

http://www.filtersusa.com/results.cfm?categoryid=22

http://www.unclejoes.com/furnace_filters_cut_to_fit.htm

It is just plain cut to fit filter. The style given to me has a tacky blue side to it, hepa for hospital use. But, it seems to work great. What is nice, not only is it consistent, but you can cut panels the same size to match cabinets, and if making a MLTL, easily weighed to attain the correct lbs. per sq. in.
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Old 13th August 2007, 03:06 PM   #17
gychang is offline gychang  United States
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Quote:
Originally posted by zayne742
Will find out, but in the meantime.

http://www.filtersusa.com/results.cfm?categoryid=22

http://www.unclejoes.com/furnace_filters_cut_to_fit.htm

It is just plain cut to fit filter. The style given to me has a tacky blue side to it, hepa for hospital use. But, it seems to work great. What is nice, not only is it consistent, but you can cut panels the same size to match cabinets, and if making a MLTL, easily weighed to attain the correct lbs. per sq. in.

great, thanks.

gychang
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Old 13th August 2007, 03:33 PM   #18
Jim G is offline Jim G  Canada
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Default chang

Would the hemp 8 be a candidate for the chang?
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Old 13th August 2007, 04:36 PM   #19
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I doubt it'd go straight in, but there's no reason why one couldn't be designed for it. I'm snowed under with work at present, but I'll do my best to look into it in the near future.
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Old 14th August 2007, 07:42 PM   #20
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Hi Gychang!

I am curious how you feel about the sound of the B20 in this new cabinet. As for the tweeter, the one you reference is probably fine. I may need to buy a pair to test with my current setup so we can compare notes on the overall sound of these cheap but cheerful projects. I like the B20 running full out with the piezo on top, but cutting a little deeper down into the B20s response may not be such a bad idea. This may be the best way to take classic components and bring them up to modern standards. The cabinet can be key and the way it enhances the sound will need description in loving detail when you get a chance.

Thanks,
Godzilla

PS, I do feel you will want a tweeter with the B20.
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Old 14th August 2007, 08:58 PM   #21
gychang is offline gychang  United States
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Quote:
Originally posted by Godzilla
Hi Gychang!

I am curious how you feel about the sound of the B20 in this new cabinet. The cabinet can be key and the way it enhances the sound will need description in loving detail when you get a chance.

Thanks,
Godzilla

I can't wait to hear them, but since I plan to do this one right, I will have to put on a proper finish followed by mounting the driver etc. At earliest probably in 2 wks due to my regular full time job. (at times like this I wish I was unemployed...)


I have been told by a reliable source, a tweeter from partsexpress
http://www.partsexpress.com/pe/psho...FTOKEN=83033797
will work well with 4uf capacitor on + side of the tweeter, that will result in crossing at 5KHz. when used with the Pioneer. No other crossover needed.

Is it right that crossover is not needed?

thanks,

gychang
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Old 14th August 2007, 09:18 PM   #22
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>>> 4uf capacitor on + side of the tweeter, that will result in crossing at 5KHz. when used with the Pioneer. No other crossover needed.

>>> Is it right that crossover is not needed?

This is the technique used by most every fullranger (builders/hobbyists whatever you want to call us) out there. We let the main driver run all out without crossover. All you are doing is adding a helper tweeter. I do the same thing with the B20 and the piezo tweeter but I use a different value cap (and resistor). The tweeter you reference does not require the resistor. So a single capacitor (of desired value) would basically roll into the response of the B20 at a mild 6db per octave. You are essentially blending the two drivers together rather than choosing a crossover point and building a crossover for both drivers to meet at that point.

I think you should try a few other capacitors with different values to make sure 4uf is ideal. It may be perfect or it may require a bit of tweaking.

How are you thinking of mounting the tweeter? Front? Back?

Godzilla
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Old 14th August 2007, 09:21 PM   #23
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Also, a little trick is to wire the tweeter in reverse of the woofer, puts it out of phase and gives a smoother response when running with a full range driver. You may want to also check out:

http://www.partsexpress.com/pe/showd...number=275-070

Very smooth response. Currently using this in my BIB's using the Pioneer 4.5" fullrange, same as your other BIB's. I love this set, great for music, theater, you name it.
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Old 14th August 2007, 09:27 PM   #24
RKH is offline RKH  United States
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Quote:
Originally posted by zayne742


Very smooth response. Currently using this in my BIB's using the Pioneer 4.5" fullrange, same as your other BIB's. I love this set, great for music, theater, you name it.
Sorry if off topic ... please move if required.

I've looked at the 4.5" Pioneer fullrange a couple of times. What BIB cabinet dimensions did you use? The specs are similar to the FE103 if I recall correctly.

Cheers,
Ryan
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Old 14th August 2007, 09:40 PM   #25
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This was dervived from GM's formula.
Fs 70
Vas 0.31
Qts 0.35
Line Length 96.175
Folded Height 48.088
Vb 1.669
Sm 59.977
Depth 9.210
Width 6.512
zdriver 20.870
a-b-c 4.605

Pretty much the size mine are, Gychang's were:
"El Cheapo speaker BIB demension: (Scottmoose)
Try a 120in line length, driver at 24in down from the sealed end, 70in^2 terminus area. Inside demensions: 7x10, height:60, speaker placement: 24 from top to middle of the speaker, inside slanting baffle ends 5 from the floor and 5 from front and 5 from back."

Mine sound great, not sure if there is much benefit from the taller, with a bigger terminus.
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