DIY Sound Group 88 Special Build Thread and Guide - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 28 Old 02-26-2015, 09:06 AM - Thread Starter
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DIY Sound Group 88 Special Build Thread and Guide

I am new to DIY speaker building, but not new to DIY projects in general (i.e. home improvement projects). This thread shows my first build of 2 88 Specials for a LR setup (phantom center) from DIY Sound Group.

Both of them were expertly packed and shipped by Erich! For all those "on the fence”: the ordering, shipping process, and quality of components (i.e. flat pack, etc.) is extremely well done and professional!

While searching through the forums I was able to get answers to all of the questions I had while building, but continually struggled with "which bookmark had the answer" or "which page of this thread talked about XYZ." It seemed like this problem would get even worse when I started a subwoofer, surround speakers, or a third 88 special for a dedicated center in a few months.

I saw other posts where builders (especially new builders like myself) were struggling with the same issues.

So I decided to try creating a "Build Guide" that had step-by-step instructions as well as alternate choices for the build steps. I nicknamed it the "FUD Buster" since I also wanted to remove the "Fear, Uncertainty, and Doubt" that occurs for a builder considering their first project.

The guide is complete through the crossover assembly, but doesn't have details on sound deadening, putting the front baffle on, attaching the speakers, final finishing the outside of the box, etc. I have done most of those steps but haven't added them to the guide. I also just setup both in their final spots, so I can't do a detailed review, but first impressions are very good!

Hopefully this guide is helpful to others! Thank you to Jeff for designing the speakers and Erich from DIY Sound Group for the flat packs, website, etc.! Also thank you for all those who actively answer questions in the forums!

Here are thumbnails for two of the pages to give an idea of how the guide is setup without having to download the full version.




The link below is to the full 25 page guide and is an approximately 5 MB lower resolution PDF version of the guide (ebook resolution). The full version is closer to 7.5MB, but I think the smaller file is high enough resolution to be useful.

https://www.dropbox.com/s/2me8s4oeek...-2-22.pdf?dl=0

Note: The link is on Dropbox which does have per-day download limits. If for some reason it isn’t available just wait a day and hopefully it can be downloaded the next day.
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post #2 of 28 Old 02-26-2015, 09:51 AM
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I don't have the means to verify if your write-up is correct, but if it is, you did a heck of a job! Welcome to AVS, you'll fit right in.
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post #3 of 28 Old 02-26-2015, 12:01 PM
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^ +1
just ordered an "88" to try as a center
definitely be checking it all out . . .


thanks

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
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post #4 of 28 Old 02-26-2015, 12:38 PM
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I just built 3 of these about a month or so ago and love them. I am happy to see more people building them. Everything looks great in this write up
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post #5 of 28 Old 02-26-2015, 12:42 PM
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^ could you describe type and how much foam lining?

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
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post #6 of 28 Old 02-26-2015, 12:42 PM - Thread Starter
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@asarose247 I don't have the section on placement of the crossover in the guide yet, but building the crossover as two-sided drill-through makes it smaller and then it is much easier to put the crossover on the left (or right) side of the box and in the upper part of the cabinet by the waveguide. On the first speaker I did all the solder connections on the same side as the components and then put the board behind the woofer on the back of the box. It definitely works, but after putting foam in to stop sound reflections it seemed less than ideal to put the crossover right behind the woofer (lots of builds have it behind the woofer, I have no idea if there is an actual measurable difference in sound quality). I built my second speaker with a two sided crossover and it finished so much nicer that I am considering going back to the first and redoing the board just to match.

Of course no one will know but me! <--- is this the "sickness" everyone talks about
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post #7 of 28 Old 02-26-2015, 12:48 PM
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^"sickness"
I know not of which you speak, Sir
in the last 18 months or so I've built 6 subs, all for me!
I'm doing an 88 to try as a center, could turn into LCR build
thanks for the heads up on the xo build

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
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post #8 of 28 Old 02-26-2015, 01:07 PM - Thread Starter
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@asarose247 I used the mattress topper from Target (or Walmart, or whatever big chain is nearby). It just has to be open-cell foam. I have seen others use Denim Insulation, but I couldn't find it locally.

Here is the first speaker with the larger crossover.


Here is the second speaker with the smaller crossover.


In the second picture you can see I added foam on the vertical cross braces (the 3 smaller pieces). I verified with Erich that it probably wasn't necessary.

Also you can see in the second image on the left side in the bottom part of the box that I didn't put any foam where the ports go. Others have put foam there, but it would need to be thin... either user thinner foam or shave off the wavy part of the foam so that there is clearance when you put the ports in. Oh, and be very careful if you try and dry fit the ports (I didn't dry fit them), they are very hard to get out!
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post #9 of 28 Old 02-26-2015, 01:14 PM
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all right, all right, all right


exactly what the doctor ordered
I've got a fever for building . .


and thanks

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
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post #10 of 28 Old 02-26-2015, 01:19 PM
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addendum


Alex, I take "foam topper" for $2000
Answer: " It looks like 2 inches!"


Contestant (me);What is the thickness of the foam topper in that 88 special?
Did I get it?

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
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post #11 of 28 Old 02-26-2015, 04:42 PM
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This is an awesome guide! You put a lot of work into it, that's for sure. You even provide drilling templates for the crossover boards...outstanding work. This is sticky-worthy here and especially on the DIYSG forums. Two big thumbs up!
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post #12 of 28 Old 02-26-2015, 05:30 PM - Thread Starter
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@asarose247 I'll give you $500 for getting close... It's 1 1/2, but it doesn't have to be exact. And from pics of denim insulation that is usually thicker, the one I saw with carpet pad was thinner.

@michaelddd Thank you I appreciate it!!!
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post #13 of 28 Old 02-26-2015, 06:15 PM
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@bitmap42




This is the kind of organized thinking that will make and allow this hobby to grow
people will understand better, be less intimidated and become bigger possibility thinkers


thanks

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
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post #14 of 28 Old 03-08-2015, 11:39 AM - Thread Starter
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I haven't written anymore in the guide, but I did get the first speaker finished with the grill. This is actually metal from a fireplace surround that I bent into shape by hand. The diameter of the curve is around 3 inches (the top of a pint of paint to be exact).



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post #15 of 28 Old 03-08-2015, 11:42 AM - Thread Starter
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I should have included this also. This shows the neodymium magnets that are put into the front. The magnets grab the metal in the grille, but I added two additional magnets to the top of the grille itself (shown in previous post, they are epoxied into the grille) just for extra holding strength on the top.

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post #16 of 28 Old 07-11-2015, 06:24 PM - Thread Starter
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Just finished my Infinity Subwoofer (see my signature for that build thread).

Here is a picture of the 88 Specials and Subwoofer in my family room.



The 88 Specials with the subwoofer are amazing!

And one more thanks to Erich for DIYSoundGroup and Jeff for designing the 88 Specials!
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post #17 of 28 Old 07-12-2015, 02:55 AM
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Thanks for taking the time to make this guide. I am sure that it will help many people. I have just one question. Why do you have them upside down?
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post #18 of 28 Old 07-12-2015, 06:03 AM - Thread Starter
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Quote:
Originally Posted by Tip24/96 View Post
Thanks for taking the time to make this guide. I am sure that it will help many people. I have just one question. Why do you have them upside down?
I wanted the shelves high enough that I could put the subwoofer under them and I wanted the shelves to put the speakers centered vertically next to the TV. When the 88s are on the shelf with the waveguide on top the waveguide ends up being above ear level. Flipping them with the waveguide on the bottom puts the waveguide at the correct height.

End result: The sound is noticeably better in this configuration!
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post #19 of 28 Old 02-13-2016, 07:41 PM
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Bit this is an excellent and informative thread thank you. I just picked up 1/2" tk stuff (egg crate shape) from Walmart to pad out my Volt 8 LX's. What is your opinion? Is that too thin? Getting the feeling i should return and look for thicker material but have no idea if that even matters...

Last edited by ddigler; 02-13-2016 at 07:47 PM.
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post #20 of 28 Old 02-14-2016, 01:41 PM - Thread Starter
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Quote:
Originally Posted by ddigler View Post
Bit this is an excellent and informative thread thank you. I just picked up 1/2" tk stuff (egg crate shape) from Walmart to pad out my Volt 8 LX's. What is your opinion? Is that too thin? Getting the feeling i should return and look for thicker material but have no idea if that even matters...
I saw the pictures in your build thread for the Volts, what you have looks good. It doesn't need to be too thick, just enough to knock down the reflections.
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post #21 of 28 Old 11-03-2016, 11:01 AM
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@bitmap42 @Cam Man @Erich H

How tight are the braces suppose to be in the dado of the 88 Special? Mine have been sitting in the garage for 14 months and I"m just starting the build and can't get the braces all the way flush. Too tight. Just curious is this normal to be this tight or did my wood swell? Thx
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post #22 of 28 Old 11-03-2016, 11:10 AM
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14 months in a garage is a pretty long time before assembly and it would depend on humidity and temperature fluctuations. That would be the case for any wood that's already been cut. The brace should sit in the dado and barely move.

Just get a piece of sandpaper and sand down the ends of the brace that go .25" into the dado and you'll be fine. It's no probably tapping them in with a mallet either.

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post #23 of 28 Old 11-03-2016, 11:30 AM
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Quote:
Originally Posted by Erich H View Post
14 months in a garage is a pretty long time before assembly and it would depend on humidity and temperature fluctuations. That would be the case for any wood that's already been cut. The brace should sit in the dado and barely move.

Just get a piece of sandpaper and sand down the ends of the brace that go .25" into the dado and you'll be fine. It's no probably tapping them in with a mallet either.
Tapping isn't what I was doing. I hammered them pretty good and still not flush. I definitely don't like dado's.
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post #24 of 28 Old 11-03-2016, 11:40 AM
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Originally Posted by redliner140 View Post
Tapping isn't what I was doing. I hammered them pretty good and still not flush. I definitely don't like dado's.
Erich is 100% correct. Wood will absorb moisture. dado's are your best friend. Again ....do some healthy sanding and even if you oversand a bit, simply apply a good amount of glue and all should be just fine.
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post #25 of 28 Old 11-03-2016, 12:54 PM
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What are they not flush with? Do you mean you tapped them into the dados and they aren't flush with the side panels?

Also, what type of adhesive are you using?

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post #26 of 28 Old 11-03-2016, 01:02 PM
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Originally Posted by Erich H View Post
What are they not flush with? Do you mean you tapped them into the dados and they aren't flush with the side panels?

Also, what type of adhesive are you using?
Correct, not flush with the back. No side panels yet, just the braces. PL Premium. I ended up clamping the braces down to hold them. Don't know how well it's going to hold because the glue was sitting for a while before I clamped them.
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post #27 of 28 Old 11-03-2016, 01:14 PM
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PL adhesive is very thick and if you put too much in the dado it can't squish out like wood glue does. That could cause the braces to not push all the way into the dado. If the glue was sitting in the dado for a while before you clamped them, then it might have gotten even thicker and made it a bit harder to clamp all the way down. Sanding should fix any issues though.

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post #28 of 28 Old 11-10-2016, 10:11 AM
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Quote:
Originally Posted by redliner140 View Post
@bitmap42 @Cam Man @Erich H

How tight are the braces suppose to be in the dado of the 88 Special? Mine have been sitting in the garage for 14 months and I"m just starting the build and can't get the braces all the way flush. Too tight. Just curious is this normal to be this tight or did my wood swell? Thx
Sorry, been away for ages. I had zero problem with fit, but I assembled immediately.
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