My Cheap Thrills Thread - AVS Forum
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DIY Speakers and Subs > My Cheap Thrills Thread
wormraper's Avatar wormraper 10:33 AM 07-20-2013
Ok guys, after much debating and hemming and hawing I've decided on the cheap thrills for my new L/C/R to replace my polk Monitor 70's and CS2 center. I JUST received the Celestion drivers and xover components from Parts Express and I'll be receiving the "kit" portion of the cheap thrills from Eric in the next 4 days (impatiently pacing back and forth). now the BIG thing for me will be the Crossovers. I'm a newb to speaker building (just done subs in the past) so I've never had to do a crossover. I have all the components listed on the Cheap Thrills page, but I noticed that when I looked up people's SEOS build threads they all had a piece that I noticed wasn't included in the components list (of any build actually). I circled the pieces in the picture below. I'm ASSUMING that it's just something to make connecting the wires a bit easier, but I'm not sure (remember with crossovers I'm a complete child so be gentle )




my buddy and I are each building a trio of them for L/C/R channels and have twin THT's each to back them up on the low end so building boxes with MDF shouldn't be a big thing.

Looneybomber's Avatar Looneybomber 10:55 AM 07-20-2013
You're right, it's for easy connecting. Your other option is to solder directly.
Crossoverreinforcement.jpg
wormraper's Avatar wormraper 10:59 AM 07-20-2013
ahhh, that's what I was wondering. is it something simple that I can pick up at radio shack or home depot? and what is the piece CALLED (I kinda like the look and security of those screw down plugs vs just soldering a crap tone of speaker wire together)
turbosc297's Avatar turbosc297 12:51 PM 07-20-2013
Mrkazador's Avatar Mrkazador 12:55 PM 07-20-2013
wormraper's Avatar wormraper 02:15 PM 07-20-2013
Quote:
Originally Posted by turbosc297 View Post

Those are my boards lol

http://www.parts-express.com/pe/showdetl.cfm?partnumber=090-862

nice n cheap at Parts express. wish I'd have thought of those BEFORE I placed my order with them. ah well.

coming from someone who's built the cheap thrills (and since I don't have access to the crossover schematics yet till I get my supplies from Eric). how many terminal blocks would I need per speaker to make the crossovers? (I've seen it vary on the design)
turbosc297's Avatar turbosc297 02:23 PM 07-20-2013
I built the tempests. But you can figure one for the amp input, and one for the xover output to each driver. (3 per speaker)
wormraper's Avatar wormraper 02:29 PM 07-20-2013
Quote:
Originally Posted by turbosc297 View Post

I built the tempests. But you can figure one for the amp input, and one for the xover output to each driver. (3 per speaker)

sweet. that makes it easy. 9 total for my L/C/R setup then.
mhutchins's Avatar mhutchins 03:00 PM 07-20-2013
Here is another option using a single barrier strip. The schematic is on the DIY Sound Group Forum for this design.



I just got my kits today and I am so excited. I just wish Erich had the flat packs ready so I could start building the boxes and listen to these beasts! My woodwoorking skills are not the best, so i really don't want to start cutting up MDF to try and make boxes. On the other hand, I neeeed my 'Thrills!!!!

biggrin.gif
Mfusick's Avatar Mfusick 03:03 PM 07-20-2013
Ill be curious to hear your opinion
wormraper's Avatar wormraper 03:30 PM 07-20-2013
Quote:
Originally Posted by mhutchins View Post

Here is another option using a single barrier strip. The schematic is on the DIY Sound Group Forum for this design.



I just got my kits today and I am so excited. I just wish Erich had the flat packs ready so I could start building the boxes and listen to these beasts! My woodwoorking skills are not the best, so i really don't want to start cutting up MDF to try and make boxes. On the other hand, I neeeed my 'Thrills!!!!

biggrin.gif

now that's a CLEAN looking crossover board. I like the top design. although my brain is having a hard time connecting things on the back lol. (not spacially oriented by nature). I like the compact look though and a six way terminal block is pretty clean looking.

you mind linking WHERE you find that schematic on the diysoundgroup forum? I couldn't find it.
mhutchins's Avatar mhutchins 03:42 PM 07-20-2013
Thanks,

The boards are roughly 6"x7" and I was going for a more "Pro" look for the finished product, and I wanted to be sure the board would fit between any internal bracing in the flat packs.

For the wiring, I challenged myself to see if I could come up with a layout where no wires crossed, so if I wanted, I could actually make a printed circuit board for the design. I admit, the wiring layout is convoluted...I guess I'm a slave to appearance!
wormraper's Avatar wormraper 03:50 PM 07-20-2013
Quote:
Originally Posted by mhutchins View Post

Thanks,

The boards are roughly 6"x7" and I was going for a more "Pro" look for the finished product, and I wanted to be sure the board would fit between any internal bracing in the flat packs.

For the wiring, I challenged myself to see if I could come up with a layout where no wires crossed, so if I wanted, I could actually make a printed circuit board for the design. I admit, the wiring layout is convoluted...I guess I'm a slave to appearance!

lol, challenging is right. my brain has smoke curls trying to trace all the wires back to their locations biggrin.gif

I'll slog through that thread so hopefully I can come up with a layout that works.
mhutchins's Avatar mhutchins 05:22 PM 07-20-2013
If you click on the word "schematic", it should open up the discussion for the Cheap Thrills design.

Link : http://www.diysoundgroup.com/forum/index.php?topic=221.0
wormraper's Avatar wormraper 05:50 PM 07-20-2013
Quote:
Originally Posted by mhutchins View Post

If you click on the word "schematic", it should open up the discussion for the Cheap Thrills design.

Link : http://www.diysoundgroup.com/forum/index.php?topic=221.0

lol, thanks, I actually found it out when my mouse accidentally brushed across the word "schematic" and I saw it change into the "clickable" icon... kind of a "durrrrrrrrr" moment there
HopefulFred's Avatar HopefulFred 07:18 PM 07-20-2013
I am just finishing mine up - I have two up and running. For reference, here's the image of the XO schematic


I took a slightly different approach and separated the woofer components from the tweeter components. My work is a little sloppy, maybe, but the boards work. Maybe you can make out where I've labeled the inputs/outputs in sharpie. Notice that the amp connections are soldered together at the terminal rings for the binding posts. Here's the front:


Here's the reverse:

Mfusick's Avatar Mfusick 07:07 AM 07-21-2013
Fred I am looking forward to your impressions in your theater build thread biggrin.gif

I've been watching you wink.gif

Nice progress BTW.
wormraper's Avatar wormraper 10:08 PM 07-22-2013
al right. for people who have done flat packs before. I MAY have access to a CNC machine so we were gonna just create our own flat packs basically. for the dados... how deep and wide are they? I'd assume about .75-.77 inches for the width, but how deep do they into the wood ??
wormraper's Avatar wormraper 08:58 AM 07-23-2013
oh and one more idea. I was thinking of using Arauco Plywood from home depot (3/4 inch thick) instead of MDF for weight issues. I know Bill Fitzmaurice uses Arauco in his THT builds as an alternative, but didn't know if it was acceptable in a speaker build for any weird reasons. any thoughts?

OR

I was thinking 1/2 Baltic Birch... I know BB is much stiffer than MDF so I was wondering if I could do 1/2 inch baltic birch (the good stuff from a lumber yard) vs. the 3/4 mdf
Erich H's Avatar Erich H 09:30 AM 07-23-2013
You'll want to use 3/4" material.

If the CNC machine doesn't have a vacuum to suck the panels down on the table, you don't want to cut plywood with dados or rabbet joints. They will be warped if the wood is warped.
wormraper's Avatar wormraper 09:32 AM 07-23-2013
Quote:
Originally Posted by Erich H View Post

You'll want to use 3/4" material.

If the CNC machine doesn't have a vacuum to suck the panels down on the table, you don't want to cut plywood with dados or rabbet joints. They will be warped if the wood is warped.

lol, sorry, the CNC machine with dado's would ONLY have been with MDF. the plywood option would only have been with standard table saws etc and glue no dados. dados in plywood would be fing nuts I assume

ok, no 1/2 inch BB ... well that means Arauco or MDF it is then. since BB is about $50 a 5x5 for 3/4 material. oof
mobeer4don's Avatar mobeer4don 10:35 AM 07-23-2013
Use a dado blade to cut dados in plywood. No big deal. Or you can use a router and straight edge to cut them.
andy497's Avatar andy497 01:09 PM 07-23-2013
Here's my crossover for a Cheap Thrills if this helps anyone. I went for compact with minimum wire runs. Inductor placement might not be optimal, but I think they are far enough apart for little interference. I hope so anyway.



Edit: Just for reference, the above black lamp cord is going to ground at each point. I know it looks like one is touching a positive terminal, but it is indeed snaked over to the negative at the solder point.
wormraper's Avatar wormraper 01:29 PM 07-23-2013
Quote:
Originally Posted by andy497 View Post

Here's my crossover for a Cheap Thrills if this helps anyone. I went for compact with minimum wire runs. Inductor placement might not be optimal, but I think they are far enough apart for little interference. I hope so anyway.


thanks, those up close shots made it so I could see the wiring a bit easier. I'm assuming that those two 6 ohm large resisters were just paired together in place of the 12 ohm resistor from the parts list (I noticed you had an extra resistor once I counted)
HopefulFred's Avatar HopefulFred 02:43 PM 07-23-2013
Careful - the two 6 ohm resisters in parallel make 3 ohms - which is correct. The 12 ohm resister is in the tweeter section parallel with the smaller cap.
wormraper's Avatar wormraper 02:45 PM 07-23-2013
Quote:
Originally Posted by HopefulFred View Post

Careful - the two 6 ohm resisters in parallel make 3 ohms - which is correct. The 12 ohm resister is in the tweeter section parallel with the smaller cap.

durr, you're right, the 12 ohm is already right next to the 1.5uf capacitor. that's what I get for just taking a quick glance. (I blame it on 4 hours of sleep last night)
wormraper's Avatar wormraper 01:50 PM 07-24-2013
thinking of spraying a flat black paint on these things. Can I use a standard latex paint on those or should I use an acrylic paint that's sandable?
HopefulFred's Avatar HopefulFred 02:14 PM 07-24-2013
I don't know about all the details - but I used Rustoleum flat black enamel because I was done fooling with it and wanted something I could pick up at a local store - Lowes had plenty and the label says it's extra durable, which will be handy when positioning my 64 pound speakers. I wouldn't say I regret it, but I won't be using it for speakers that I have to look at. Probably most of the problem was in my prep work, which included only flush trimming with a router, a light sanding and then a coat of sanding sealer. The paint seems okay, but the overall finish is pretty crummy. For future builds, I'll be upgrading to duratex.

This picture gives a pretty good idea of how it came out, despite being poorly focused. I don't have any pictures of the edges that show the places that didn't get enough sanding or sanding sealer and have uneven uptake. There are a number of areas where the finish feels uneven.

JWagstaff's Avatar JWagstaff 02:50 PM 07-24-2013
Quote:
Originally Posted by wormraper View Post

thinking of spraying a flat black paint on these things. Can I use a standard latex paint on those or should I use an acrylic paint that's sandable?

make sure you prime the mdf with a shellac base, like zinsser bin. it will just soak up paint without a primer.
wormraper's Avatar wormraper 02:56 PM 07-24-2013
Quote:
Originally Posted by JWagstaff View Post

make sure you prime the mdf with a shellac base, like zinsser bin. it will just soak up paint without a primer.

shellac based primer? will do. was gonna uze zinsser bullseye, but I'll grab a quart of the shellac primmer
Tags: Polk Audio Monitor70 Series Ii Floorstanding Loudspeaker , Polk Audio Monitor Series Cs2 Center Channel Speaker Single Cherry
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