Ideas for front mains

[Mongrel714]

Hey veryone, Hope you dont think I'm slacking here, been very busy at work, I am looking at a couple of designs on MTM type speaker projects to model my mains after, I think it would be much easier for my first attempt to use a proven design, here is a couple I'm looking at:
http://www.htguide.com/forum/showthread/php4?t=11321
http://www.partsexpress.com/projects...trix/index.cfm
Building a crossover from a diagram would help me to understand there construction much better than from scratch, I would model the enclosure from the projects above as close to original as posible of course working it into my design. I'm gonna stick to a low budget for my first try. let me know what you think

[Mongrel714]

Thanks again thylantyr, you are a wealth of information, I like the drivers on that project, If you were doing this would you go with the 2.5 version crossover?? I'm working with his enclosure calcs for the tower enclosures but not getting them to come out right, but I'm rushing, got to get out the door, taking my Son to a wolf sanctuary today, talk to ya later.

[Mongrel714]

Vas is recomended enclosure size, right??,

[Mongrel714]

thylantyr wrote:

I posted that because it's the same drivers with many different crossover designs, this gives
you some flexibility if you want to experiment to see which ones sound best to you.

Awww... A X-over training exercise, thank you Sensai, I will make the X-over easy to get to on the back so I can experiment with them, thanks.

[JCD]

The drivers used in those designs (as well as the designs themselves) are all very popular and are supposed to offer some great sound. If you go this route, and want to incorporate it into the design you've come up with, just make sure that you section off the area behind the drivers with the proper volume and that the speaker is as wide as the design calls for. That last part is going to be pretty important.

That being said, I'd like you to jump a little further up the food chain for the design -- especially since you've said you're going with a proven design. If I didn't know you already had the wood skills, I might be inclined to say OK with the designs you've referenced, but you've definitely got the wood skills, so I say go for a something you think will be the final product. It's a lot of work to get these things completed, so why double it up? Unless of course you intend to use these "practice" speakers as a second set for your garage or something similar.

Just my opinion.

JCD

[Mongrel714]

JCD wrote:

The drivers used in those designs (as well as the designs themselves) are all very popular and are supposed to offer some great sound. If you go this route, and want to incorporate it into the design you've come up with, just make sure that you section off the area behind the drivers with the proper volume and that the speaker is as wide as the design calls for. That last part is going to be pretty important.

That being said, I'd like you to jump a little further up the food chain for the design -- especially since you've said you're going with a proven design. If I didn't know you already had the wood skills, I might be inclined to say OK with the designs you've referenced, but you've definitely got the wood skills, so I say go for a something you think will be the final product. It's a lot of work to get these things completed, so why double it up? Unless of course you intend to use these "practice" speakers as a second set for your garage or something similar.

Just my opinion.

JCD

Thanks Jacen, I def will stick with my design, I've been working with the numbers on the extended low end version, but Im having trouble getting my design around the box design, and, I may be feeling the effects of a 16 hour work day here, but, the box dimensions do not come out to his recomended sizes, 1.2 cu ft, and 1.7 cu ft, the extended bass versions dimensions would have to be much larger to come out to 1.7 cu ft. making my enclosure way to tall, so plan b would have to use the shape of my box to reach the 1.7 cu ft mark, which would mean having a 5 sided box, (9" baffle mounted on the front corner of enclosure) as long as my volume is right and I stick with a 9" baffle, do you think it will sound decent?? Thanks again!

[JCD]

A few comments/questions:

1. How deep is your cabinent as is? It doesn't look very deep now that I take a good look at it.
2. I wouldn't worry about going with the extended bass version -- you've already got a wicked looking sub to handle that area of the audio spectrum. Stick with the 1.2f^3 version
3. I'm not sure what you're trying to say about the 5 sided speaker -- here is the answer I think you were going for: I'd use the same general shape as you have currently but change the dimensions slightly. Instead of being 16" wide, make it 9". Since I can't tell what the depth is, make it 13.5". In other words. I'd probably build the design you have around a box that is going to be 9"x22"x13.5".
4. Also, I can't tell, but are the sides rounded? Sort of like a tube with a slice taken off the front?

JCD

[Mongrel714]

JCD wrote:

A few comments/questions:

1. How deep is your cabinent as is? It doesn't look very deep now that I take a good look at it.
2. I wouldn't worry about going with the extended bass version -- you've already got a wicked looking sub to handle that area of the audio spectrum. Stick with the 1.2f^3 version
3. I'm not sure what you're trying to say about the 5 sided speaker -- here is the answer I think you were going for: I'd use the same general shape as you have currently but change the dimensions slightly. Instead of being 16" wide, make it 9". Since I can't tell what the depth is, make it 13.5". In other words. I'd probably build the design you have around a box that is going to be 9"x22"x13.5".
4. Also, I can't tell, but are the sides rounded? Sort of like a tube with a slice taken off the front?

JCD

All right, I've got this thing close to where it needs to be, The RS180 drivers call for .88 cu ft ea totaling out to 1.7 cu ft, how critical is it to build the enclosure to that number? the interior enclosure itself would be 9"w x 11"d x 42.25"h, making the exterior enclosure roughly 19"w x 20"d x 66-72"h, which isn't bad, but I would like to get the enclosure down to 60" tall, and some what narrower, check out the drawing let me know your thought, cheers

Oh yeah, I ordered my drivers today!!

[Anthony]

I have nothing to add here except that I love your unique design and enthusiasm!

I have the last parts of my speakers on the way as well. I'm hoping to prototype this weekend (fingers crossed). I'm taking the opposite approach as you -- I picked drivers in a very boring (flat, open) baffle. I figure I'll come up with an aesthetically pleasing design later. Talk to me in a couple of years when I'm still listening to my unpainted boring MDF baffle

Good luck and keep up the posts and pics!

[JCD]

Mongrel714 wrote:

All right, I've got this thing close to where it needs to be, The RS180 drivers call for .88 cu ft ea totaling out to 1.7 cu ft, how critical is it to build the enclosure to that number? the interior enclosure itself would be 9"w x 11"d x 42.25"h, making the exterior enclosure roughly 19"w x 20"d x 66-72"h, which isn't bad, but I would like to get the enclosure down to 60" tall, and some what narrower, check out the drawing let me know your thought, cheers

Oh yeah, I ordered my drivers today!!

You can still go for the 1.2 cu ft box that they recommend for the "standard" configuration. It'll go plenty low enough since you've got your sub and will probably give you better performance in the higher frequencies. That being said, it looks like you're within ~3.2% of the extended bass version, so I think you'd be OK with that. However, I still see an issue with the width of the ultimate cabinet. You're interior volume appears to be fine, but the actual width you're saying is 19". The problem you've got here is the crossover that was developed for speaker is taking into account a 9" wide baffle when they designed their BSC. So, I think you're OK with the volume you're using, but I'm worried about the baffle width and how it is related to the crossover.

And I'm almost as excited as you about you starting this project!
You're much faster and innovative than I am with your designs!
I've been working on my latest projects for ~2 months and I'm still not fully assembled!

JCD

[JCD]

I thought of some other quesitons :
How much bracing did you include in your calculation?
And how big of a port did you assume?
And, finally, how much volume did you calculate for the back of the speaker?

So many questions..

JCD

[Mongrel714]

JCD wrote:

I thought of some other quesitons :
How much bracing did you include in your calculation?
And how big of a port did you assume?
And, finally, how much volume did you calculate for the back of the speaker?

So many questions..

JCD

Wow, thanks guys, I guess I am pretty excited about this, I've done alot of different projects in my life but none of them have gave me the feeling that DIY speakers have, after hearing how my sub turned out and realizing the quality of product you can achieve I'm just blown away, and seeing the look on un-suspecting listners faces when you shake their spleen loose doesent hurt either!, so thank you Anthony and Jacen, your comments mean alot.
First off, my speaker enclosure box size is: 9" wide, 11" deep, and, 42.25" tall, after I add the wood to the outside of that enclosure to give it the shape, it will be, 19" wide, 20" deep, and 66-72" tall. As for bracing, I figured 2 diff sizes, two full braces which would support sides, front, back @ 30.75 cu in, (4-2.5" x 1.5" holes in that one), and two side braces which would be a 2" x .75" piece running side to side @ 9 cu in.
The port will be 6.5" x 3", which comes out to 45.9 cu in of course this depends on final enclosure volume. as for the back of the speakers I could not find any info on that, and in my exausted state these last few days I didnt realize I could figure that on my own, I will do that later tonight, (the heat and humidity here in S.W. Florida is extreme this year and is wearing everyone out whos in it).
I'm going to go with your suggestion and drop it down to 1.2 Cu Ft. which would have a 3" x 8" port, the designer said we could use a 4" port if I was using alot of power, I like that idea, do you think it would be an improvement?
I've attached a design I'm working on for a friend at work for his car, (Shhhhhh! don't tell anybody I posted an car audio pic here!) hope you like it.
I'm also excited about putting together the X-overs, I've always been amazed by electronic parts and what they do, I've also found a DIY project for a clean box I'm going to try out, looks lijke fun!
Looking forward to your responce guys, Later.

[JCD]

I've done alot of different projects in my life but none of them have gave me the feeling that DIY speakers have, after hearing how my sub turned out and realizing the quality of product you can achieve I'm just blown away, and seeing the look on un-suspecting listners faces when you shake their spleen loose doesent hurt either!

That's awesome. I got sucked into this one just like you -- it looked like fun, I had a good time with my first job and I liked the results. Now I'm working on projects 2 and 3 and already thinking about project 4, so prepare yourself! This could be just the beginning.

after I add the wood to the outside of that enclosure to give it the shape, it will be, 19" wide, 20" deep, and 66-72" tall.

Yeah, I think that's going to be a problem. The crossover is (i'm assuming) compensating for the loss in acoustical output below a certain frequency that is based on the width of the baffle. The actual "enclosure" (i.e., the 1.2cu ft) is important for the driver's performance, but the width of the baffle is going to dictate the point at which the acoustical output of the driver starts to fall off.

With a 9" baffle, the bass output will start to roll off at 3013Hz, have a 3 db drop off at 507Hz and end with a 6db at 188Hz.
With a 19" baffle, the 3 points are 1427Hz, 240Hz and 89.21Hz.

I think this is going to be particularly important with a 2.5 situation since it's crossover is dependent (usually?) on this BSC. If I'm not mistaken, the second woofer will start it's output to compensate for the BSC.

I'm going to go with your suggestion and drop it down to 1.2 Cu Ft. which would have a 3" x 8" port, the designer said we could use a 4" port if I was using alot of power, I like that idea, do you think it would be an improvement?

I think you'll get better performance -- I certainly hope so since you're changing! as for the 3" vs. 4" -- I don't know. I wouldn't think so, but MAYBE you'll hear some chuffing at high volumes, but I seriously doubt it. Someone better at this stuff can hopefully chime in on this one.

Some other points -- I'd make sure the tweeter is at your ear level while sitting down. ~39"-41". The drivers should also be as close together as possible.

JCD

[Mongrel714]

Heres the layout top and side view, the outside enclosure angles back from 9" to 19" there is a point coming out above it, but it angles up also as you can see on side view.
Ill follow your advice on speaker placement also, BTW Jacen, have you got any pics of your project posted? I'de like to check them out, G'night

[Mongrel714]

Hey All,
Got my woofers in today, you can really tell a difference in these and the they put in the cheapy enclosures.
Now on to todays question, Im working on my cross over design from Dr K's design 2.5 off of parts express DIY section, Im trying to get the working x- over from the schematic, I hope one of you cross over wizards will check my layout to see if it will work.
Also, there is an inductor on there listed as 16GA STEEL 5.000mH I can't find a STEEL inductor anywhere, and a parts express tech said I could prob use a reg inductor, would this work?? Opps, I missed an inductor on my top diagram, just check the bottom one, lol.

[JCD]

Man, I hope someone drops in and answers your question, because I don't know either. My assuming is a regular inductor would be ok, but I just don't know for sure. Can you provide a link to the site where the schematic is located?

Oh, and I've posted the beginnings of my project here.

JCD

[Anthony]

They probably mean steel core inductor. They are still wire wound, but the center is a metal core instead of air. Because of that they are much smaller. Metal core inductors can saturate, meaning that the core can't take any more magnetic field and the relative inductance changes. Air cores can't saturate, so they hold their nominal value regardless of the power going through them.

One thing not mentioned is the DC resistance that crossover design is expecting. All inductors have an internal resistance, due to the massive length of wire involved in making them. Ideally, you want as low as possible, but sometimes you can use that resistance to your advantage, for instance if you want to "pad" that crossover section down a bit you can use an inductor that has a slightly higher internal resistance.

But since this is your woofer section, I imagine you won't want need any padding. In that case, use the largest gauge you can afford (larger gauge -- smaller number -- less resistance). 18 gauge at a minimum, 15 gauge ideal. However, for 5mH that will be a VERY expensive inductor. $30 http://www.partsexpress.com/pe/pshow...=255-442&DID=7

Here's an iron core of the same value for $32
http://www.partsexpress.com/pe/pshow...Number=255-820
(it's probably designed to avoid the saturation problem, but would still have some distortion issues -- that is less of a problem with the bass section of a speaker)

Much cheaper, but probably has more distortion than the two above:
http://www.partsexpress.com/pe/pshow...Number=255-116

Here's the steel laminate inductor at 5 mH. I hate that they don't mention the DC resistance. http://www.madisound.com/catalog/pro...6205b11a62e699

So, enough information to be dangerous. Air core is the only way to avoid distortion and saturation, however the better ferrous, iron, or steel core inductors are designed to avoid all that as much as possible. The steel core is definitely the best bargain, but I would contact Madisound and make sure the DCR is less than 0.25 Ohms.

I hope this helps. Good luck with your build.
AC

[Mongrel714]

Jacen, your project looks awesome, Bet it sounds as good as it looks, The link for the project and crossover is: http://www.rjbaudio.com/RS180MTM/rs180-rs28-mtm.html
It is the 2.5 version x-over I'm looking at, Hope you can check that out Anthony and let me know what you think!
Now for some pics of my new babies, these speakers sound clearer in this test box than my speakers I'm running now! (Onkyos) running full range at low volume I can hear cymbals and high notes,(listening to Dream Theater, they always have neat little added things in there music) I didnt have a wooden box handy to test the speakers as Parts Express suggested so this works fine, and no scratches.