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Wayne Parham's Pi 4 Build Thread - Page 2

post #31 of 126
4/3/10 at 6:05pm
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post

I got my DE250's in the mail yesterday. Was kind of surprised to not see some sort of screen like the D220i's have?
And had a "doh" moment when I realized they are bolt on, so I can't swap them onto my JBL econowaves to have a quick listen.

Wish I could start my pi4 build, but I'm still trying to bust out my bathroom remodel. Sanding the tape/mud today. Hope to start 2nd coat tomorrow.

Eddie,
What do you mean by missing screen on the DE250?

Mine have a black screen over the 1" exit of the compression driver.
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post #32 of 126
4/4/10 at 12:39am
re: "more progress"

look'n good.

do you plan to stuff some fiberglass in there before sealing them up?
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post #33 of 126
4/4/10 at 8:03am
I also came across that post on the rope caulk and one thought that came to mind is whether there is a chance that the caulk might dry out over time and fall off the horn. I wonder if anyone has any long term experience with that method. I guess another approach might be something like a couple of layers of Dynamat extreme. The caulk is obviously a more economical approach.
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post #34 of 126
4/4/10 at 10:32am
good point bigmouth, i recall that now as well. not sure if dynamat would have the same effect. maybe just wrapping the rope caulk with duct tape would keep it from drying out over time and that is a simple, cheap, and reversable solution.
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post #35 of 126
4/4/10 at 12:20pm
Duct tape, insert sound of smacking forehead.

I was thinking of that fiberglass drywall tape but duct is much better. Maybe the black Gorilla brand duct tape. Nice and pretty. Matches the horn.
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post #36 of 126
4/4/10 at 2:13pm
Quote:
Originally Posted by nichol1997 View Post

Eddie,
What do you mean by missing screen on the DE250?

Mine have a black screen over the 1" exit of the compression driver.

Hmm, the ones I bought on eBay as "new" condition don't have this.


LL
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post #37 of 126
4/4/10 at 2:15pm
Quote:
Originally Posted by LTD02 View Post

good point bigmouth, i recall that now as well. not sure if dynamat would have the same effect. maybe just wrapping the rope caulk with duct tape would keep it from drying out over time and that is a simple, cheap, and reversable solution.

Plumbers putty isn't designed to dry out.
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post #38 of 126
4/4/10 at 8:35pm
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

re: "more progress"

look'n good.

do you plan to stuff some fiberglass in there before sealing them up?

My intention was to use polyfill from the fabric store after I install the back cover of the enclosure. I am pretty sure I will be able to get to the corners even through the window bracing.

Quote:
Originally Posted by CZ Eddie View Post

Hmm, the ones I bought on eBay as "new" condition don't have this.


I am pretty sure that mine have the screen on them. I can check tomorrow and let you know. I bought them new from Parts Express.
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post #39 of 126
4/4/10 at 8:41pm
Thread Starter 
Quote:
Originally Posted by BIGmouthinDC View Post

I also came across that post on the rope caulk and one thought that came to mind is whether there is a chance that the caulk might dry out over time and fall off the horn. I wonder if anyone has any long term experience with that method. I guess another approach might be something like a couple of layers of Dynamat extreme. The caulk is obviously a more economical approach.

I have seen Dynamat peel away from its installed location (interior car door panels). Therefore, I would be hesitant to use it.

One idea that I was thinking about was to install the rope caulk and then wrap yarn around it to permanently hold it in place.
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post #40 of 126
4/5/10 at 4:31am
fwiw, i'd still suggest something like duct tape, as that will help contain the moisture and keep the rope caulk pliable. yarn might actually wick the moisture out, decreasing the dry out time.
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post #41 of 126
4/5/10 at 1:10pm
I have some dynamat on my HVAC ductwork and it is not going anywhere without a fight.

Yarn is similar to my original fiberglass mesh tape idea which could be pressed into the surface a bit.
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post #42 of 126
4/5/10 at 6:33pm
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post

Hmm, the ones I bought on eBay as "new" condition don't have this.

Eddie,
My compression drivers have a screen on them:






More progress tonight, I glued the back panel on one of them. I wish I owned more clamps and I could have glued both of them.




I need to order my crossover parts and my veneer for the sides, tops, and bottoms. I am in between bloodwood, red oak, walnut, or zebrawood. For the front and rear of the enclosure, I was going to paint black.
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post #43 of 126
4/5/10 at 11:35pm
i'd prefer matt black, so they won't reflect screen light, but that is just me.

an interesting finish that came up recently was prefinished faux zebrawood:
http://www.avsforum.com/avs-vb/showthread.php?t=1235133
not sure if that is what you are looking for though.

high gloss zebrawood as used in the jbl arrays is nice:
http://avforum.no/forum/attachments/...y-1400-002.jpg
lot's of work required with that path, but they do look nice.

somebody made some ob-7's a while back with a really nice tiger stripe satin veneer. i can't find the link. this is the best that i have and doesn't do the finish justice.
http://www.gr-research.com/index.asp...ROD&ProdID=136
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post #44 of 126
4/12/10 at 7:10pm
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

i'd prefer matt black, so they won't reflect screen light, but that is just me.

an interesting finish that came up recently was prefinished faux zebrawood:
http://www.avsforum.com/avs-vb/showthread.php?t=1235133
not sure if that is what you are looking for though.

high gloss zebrawood as used in the jbl arrays is nice:
http://avforum.no/forum/attachments/...y-1400-002.jpg
lot's of work required with that path, but they do look nice.

somebody made some ob-7's a while back with a really nice tiger stripe satin veneer. i can't find the link. this is the best that i have and doesn't do the finish justice.
http://www.gr-research.com/index.asp...ROD&ProdID=136

Thanks for the links, definitely some nice looking speakers there.

Just an update, I ordered my crossover parts after determining what I needed. A time consuming process with all the various brands and values to choose from. I ended up going with Mills resistors, Jantzen 15-AWG inductors, and Jantzen Z-Caps. All of the components shipped from Parts Express and should be here tomorrow. I was a little surprised when I saw the shipping weight of 86 pounds!! Yikes, these components must be huge.


I am debating on which wood glue to use for paper-backed veneer. I was planning on doing the iron-on method since I have done it in the past with great success. Does anybody have first hand experience using the Heat Lock Veneer Glue ( http://betterbond.com/heatlock/heatlock-FAQ.htm ) versus regular Titebond Wood Glue ( http://www.titebond.com/IntroPageTB.....asp?prodcat=1 )?
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post #45 of 126
4/12/10 at 7:30pm
Quote:
Originally Posted by nichol1997 View Post

Eddie,
My compression drivers have a screen on them:

Thanks for letting me know!
I still have the pi4's and another subwoofer project on the backburner for now. I've really got to get my bathroom remodel finished. It's ready for the 3rd coat of mud now!
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post #46 of 126
4/12/10 at 7:31pm
Quote:
Originally Posted by nichol1997 View Post

. I was a little surprised when I saw the shipping weight of 86 pounds!! Yikes, these components must be huge.

Holy crap!
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post #47 of 126
4/12/10 at 9:01pm
Quote:
Originally Posted by nichol1997 View Post

I was a little surprised when I saw the shipping weight of 86 pounds!!

Wow, I've looked at the picture of Pi4 crossover and find it hard to believe it would weigh 43 lbs. Even if everything was made with lead.



What does the R3 weigh as it is mounted off board and not part of the picture?
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post #48 of 126
4/13/10 at 6:32pm
Thread Starter 
Quote:
Originally Posted by BIGmouthinDC View Post

Wow, I've looked at the picture of Pi4 crossover and find it hard to believe it would weigh 43 lbs. Even if everything was made with lead.

What does the R3 weigh as it is mounted off board and not part of the picture?

The crossover parts came today and the shipping label said it only weighed 8 pounds... that is more like it. Just a typo on the invoice.

I also picked up some 10 ounce polyfill batting that they sell by the yard at Joann's Fabric store.
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post #49 of 126
4/19/10 at 8:03pm
Thread Starter 
Been busy with the crossovers. It took about 5 hours to decide where to put everything and solder/ hot glue the components.







For those following along, it is imperative to place the inductors in a certain orientation and distance to try and minimize their effect on each other. I used the following link as my guidance:
http://www.troelsgravesen.dk/coils.htm



A quick check to see if everything was hooked up correctly:


And installation into the enclosure:
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post #50 of 126
4/20/10 at 10:17am
great progress.
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post #51 of 126
5/19/10 at 7:53pm
Did you not like the results, or are you just too busy listening to them?
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post #52 of 126
5/20/10 at 8:02pm
Thread Starter 
I have been busy listening to them for the past few weeks. I made the mistake of putting the drivers in the enclosure before completely finishing the exterior of them. So as of today, they are still raw mdf.

Just a note for anyone who is going to build them. When using the 3 studs on the compression driver for mounting, the horn has to be trimmed before the bolts will fit onto the studs. It was a very easy process with a razor blade.

3 studs:



Trimmed horn:












I have only tried them with the shorter ports (yellow curve on my 1st post of this thread) so they are not tuned very low. I am looking forward to trying them with the longer ports, just need to find the time to swap them. I have not measured them to see if the simulations match the design.

As for listening impressions (have only demoed them with music and with a Crown CE4000 for amplification) :
- they are very efficient and dynamic
- they can play extremely loud while staying composed (will fill a large theater without any problems)
- the midbass is punchy when turned up
- they have a very in-your-face sound to them (I am guessing this is due to the horn)
- they are extremely directional on the vertical axis (definitely need to be aimed towards the listener)
- the image of the soundstage is excellent (constant directivity plays a big role here)
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post #53 of 126
5/20/10 at 10:22pm
Good job! They will look so much better after you veneer them.

Any downsides?
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post #54 of 126
5/21/10 at 7:46am
Quote:
Originally Posted by nichol1997 View Post

As for listening impressions (have only demoed them with music and with a Crown CE4000 for amplification) :
- they are very efficient and dynamic

That's a bad combo. The CE4000 isn't the best full range amp with it's high amounts of hiss, but at least you're able to let those speakers rip with a power amp instead of a reciever.
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post #55 of 126
5/21/10 at 9:01am
I also had the opportunity to hear Nicks early results. We also had the opportunity to swap out my Audax L/R and a pair of Nick's L/R for some A/B comparisons.

The first thing you notice is the upper end "sssst" is missing compared to a 1 inch silk dome Audax tweeter. The Pi's are probably a more accurate representation of the sound as intended. Certainly won't fatigue the listener.

The second thing is that although Nick modified the box volume and porting, the bottom was less emphasized than his existing MTM L/R. I forgot what design they were but it is one of the published designs floating around. The Pi's definitely need to be mated to subs.

Overall my impression was these things like to be driven hard and with my size basement may be the ticket.
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post #56 of 126
5/22/10 at 8:07pm
Yes, I've noticed something similar with my econowave. At least if I'm understanding "ssst" right?
These are not "delicate" tweeters at all. I'm not sure how to describe it? Like when the drummer is lightly tapping on the cymbols, you might hear a less audible "ssst" sound when compared with soft domes? It could be my room though. I haven't been happy with the accoustics in this room since I moved into this house.
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post #57 of 126
5/23/10 at 6:54pm
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post

Good job! They will look so much better after you veneer them.

Any downsides?

One downside is the fact that they are so efficient that I can hear faulty recordings. Any type of flaw is easily audible.

Quote:
Originally Posted by Looneybomber View Post

That's a bad combo. The CE4000 isn't the best full range amp with it's high amounts of hiss, but at least you're able to let those speakers rip with a power amp instead of a reciever.

I have not noticed any excessive hiss. I take it that the CE4000 are known to hiss?

I will have to try a different amp to see if I can hear it or not.
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post #58 of 126
5/23/10 at 6:57pm
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post

Yes, I've noticed something similar with my econowave. At least if I'm understanding "ssst" right?
These are not "delicate" tweeters at all. I'm not sure how to describe it? Like when the drummer is lightly tapping on the cymbols, you might hear a less audible "ssst" sound when compared with soft domes? It could be my room though. I haven't been happy with the accoustics in this room since I moved into this house.

Which version of the Econowave did you build?

I think what BigMouth is referring to is high frequency roll-off of the horn/compression driver in the Pi4.
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post #59 of 126
5/23/10 at 7:59pm
Yes, high frequency roll-off but the fact is I can't hear anything over 14Khz.

http://www.freemosquitoringtones.org/
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post #60 of 126
5/23/10 at 9:14pm
Quote:
Originally Posted by nichol1997 View Post

Which version of the Econowave did you build?

I think what BigMouth is referring to is high frequency roll-off of the horn/compression driver in the Pi4.

Mine are about a year old? I built the basic, original econowave that isn't spec'd to anything in particular. Mated them up to JBL 2226H, which will go into my 4PI when I get around to ordering the crossover components & horn.

I could hear up to 15khz, but nothing past that. And just barely, at that. Or maybe that's just where my econo's fall off a cliff. I dunno which.
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