I've got the DIY bug - few questions

[mjon99]

I've been considering doing a DIY sub for a few weeks now. First I was thinking of just getting a kit, now I'm thinking of doing everything myself. Now I'm considering DIY loudspeakers too, but I have a few questions regarding both.

1. If a sub or speaker calls for 1ft^3 (for ease of understanding) do the dimensions matter? Could it be 12x12x12, 18x16x6, or 24x12x6? Or should these dimensions be as close as possible to a cube?

2. If builing an MTM speaker and let's say each driver calls for .25ft^3 if used separatley does this mean the enclosure should be .75ft^3? Or is there a formula of some sort for this?

3. Let's say the speaker from #2 above has all 3 drivers at 50w RMS/ 75w max, what would the speaker be rated at in terms of watts? 150? Or, again, is there some sort of formula for this?

I appreciate any input you might have for me.

Mike

[kexodusc]

I've been considering doing a DIY sub for a few weeks now. First I was thinking of just getting a kit, now I'm thinking of doing everything myself. Now I'm considering DIY loudspeakers too, but I have a few questions regarding both.

1. If a sub or speaker calls for 1ft^3 (for ease of understanding) do the dimensions matter? Could it be 12x12x12, 18x16x6, or 24x12x6? Or should these dimensions be as close as possible to a cube?

2. If builing an MTM speaker and let's say each driver calls for .25ft^3 if used separatley does this mean the enclosure should be .75ft^3? Or is there a formula of some sort for this?

3. Let's say the speaker from #2 above has all 3 drivers at 50w RMS/ 75w max, what would the speaker be rated at in terms of watts? 150? Or, again, is there some sort of formula for this?

I appreciate any input you might have for me.

Mike

Good questions...

1)The cubic sub generally leads to a Q value of the Butterworth recommended 0.7, great for flat frequency response. However, you may wish to alter the dimensions to accomodate your choice of woofer, tastes, needs etc...

2) You should really pay attention to the cabinets volume from the points of view of compliance, and tuning. Usually the manufacturers provide suitable ranges. Make sure the cabinets volume is large enough (or likewise small enough) to compelement the woofers. There isn't really a best "volume" per say...crossover, choice of port size, and whether or not the cabinet is ported or sealed impact this as well.

3) I think, theoretically each driver can handle 50 watts, and adding is fine, but it depends on how the power is distributed to each driver by the crossover. If, for example, the crossover sends more power to the tweeters than the woofers, well, you don't want to be drawing 150 watts total, but with 100 of that going to the tweeter alone. You've really got to know some sensitivities, efficiencies, etc to make this determination.

I'd recommend building an existing proven design, especially loudspeakers, where the crossover is really the heart and soul of a speaker, and requires the most preparation...there's tons out there.
The DIII from speakerbuilder.net is an excellent inexpensive MTM design with instructions provided, or for the more descriminating ear, I'd recommend audioreview.com's own ar.com DIY by Ed Frias...I've recently replaced my $1200 Paradigm Studio 40's with these $300 speakers. You will not be disappointed.

There's lots of great websites and books out there...partsexpress.com and diyaudio.com are good places to start...
Good luck.

[mjon99]

I can't find the ed frias speakers online. i've searched everywhere. could you provide a link.

[kexodusc]

Sure, you're gonna laugh at yourself....
Go to the very top of this page and click "LEARN" in the blue bar.

Then look for the DIY speaker by Ed Frias.

Alternatively, go to madisound.com under "kits" it might be referred to as the EFE DIY as well.

[mjon99]

Got it.
I found it at madisound.

One more question. The ar.com is a tweeter-mid and the D3 (which I have seen before) is an MTM. I would assume there is no advantage of any MTM over any tweeter-mid since you reccommended the ar.com over the D3. Correct? Or is there a noticable difference of one over the other?

[kexodusc]

Without being overly simple, one would expect a $1000 2-way speaker (the TM arrangement you refer to) to outperform a $100 MTM. Number of drivers, size, material, etc in themselves is not indicative of performance.

Typically, an MTM will have a higher efficiency than a TM speaker that uses the same drivers. This means less power to go loud. But if the drivers are different, there really isn't much to compare. There are some great advantages at the low end (bass) with the MTM.
Some feel the soundstaging on MTM's isn't as good as a TM, I'm not sure I agree with that, but I read it alot.

2 ways are typically much simpler to design well. The crossover is easier, there's less pieces to worry about, less compromises to be made, and less that can go wrong. K.I.S.S. Especially when relatively new to the hobby.

Having heard both I can share a bit with you. The D3 is a great project. Tons of tight, thumping bass for a speaker this size, and it's fairly cheap at under $150 or so to build. An excellent 1st project IMO. Very fun to listen too. But, these will require fairly good amplification capable of driving 4 ohm loads. An acquaintance of mine who did build the pair I've heard replaced $600 B&W's with the D3's. They are smooth in the treble, and present a fairly decent midrange. Here is an excellent webpage about this project:
http://www.speakerbuilder.net/web_files/Projects/D3/D3W/walk1.html

The ar.com DIY's, on the other hand, are a whole other step up. Though not as heavy in the bass, the bass it does have sounds more real, also goes quite low itself (enough for most music) and everything else is just a whole level up in terms of sound quality. Wide soundstage, excellent imaging, realistic voices. I am simple amazed how good these speakers sound for $300. I did not expect to build 3 pairs to replace my Studio 40's and 20's, but that's what I've ended up doing.

I've also built the PeeCreek (also found on speakerbuilder.net), similar to the ar.com, though a bit less detailed at the top end, with less soundstaging abilities. It's a great alternative to the ar.com DIY because you can buy those beautiful pre-built cabinets from Parts Express, and it's a cheaper than the ar.com ($50 or so). It's also alot more refined than the D3, but again doesn't have the low end. I'd put it in between the other two...the pre-fab cabinets are nice and save time.

IMO you get what you pay for here, all are great speakers. Once you start down the DIY path you'll get hooked pretty quickly though. There's tons of people who've built these. Ed Frias frequents the DIY forum here quite a bit and answers alot of questions if you include "ar.com DIY" or "EFE" in the title. You can also e-mail him personally and he's usually quite happy to assist. And there's always a few people undertaking the project here, with dozens of members happy to assist.

Same on the Parts Express forum with the PeeCreek or D3.

My advise is to decide on your budget (or how long you are willing to wait to save up) and then choose which looks best for your needs.

If you're really on a budget, the BR-1 kit at Parts Express can be had for $150 (cabinets pre-made and included) sounds very similar to the D3 in terms of quality (just less bass), and will have no problem competing against $400-$500 commercial speakers. There's a few people here who've built these as well...I've only heard 1 pair, but I was impressed. Not as fun as making your own cabinets IMO, though.

Let us know what you decide.

[mjon99]

Kex,
Thanks for the detailed response. I know I've chatted with you about a DIY sub too. Now I just have to find the time and $$$.

[kexodusc]

The time is killer for me...I started my first pair of ar.com's in August I think, didn't get them done until December!!! Then in 5 weeks I built 2 more pairs and stands to go with them...It's a very relaxing, fun, and rewarding hobby though. Much needed for someone like myself who spends most of his time doing financial work in an office.

The best part is, the DIY community online is the best I've run into yet...Totally helpful and eager to keep the DIY trend growing.

[mjon99]

i know what you mean. i too am in the financial field (accounting). as surprising as it may be i don't exactly jump out of bed in the morning anxious to get to the office so i can stare at a screen for 8 hours a day.

[Aric M L]

I too am a bit curious about DIY and my question is. When constructing a speaker or sub cabinet, obviously you'd want the fits to be as tight as possible. Is there a recommended tool for the job of getting that exact fit? Also is some sort of regular caulk good for the seams or is there some other substance I should know about?

[kexodusc]

Well, I'd recommend 3 tools as a minimum...Obviously a table saw for cutting up MDF to size. You'll definitely need a plunge router to do the driver cutouts right, maka your own jig or buy the casper jig.
Normal fixed-base router won't cut it, especially for countersinking.
And since I'm lazy, I love a good palm sander and belt sander too...
Additionally, drills, dado blades, and body-fill all come in handy too, but you could probably do without.

I'm told alot of Home Depot's or Lowe's etc, will actually cut MDF to specs for you for a fee (sometimes not). This leaves just the gluing and veneering to you.

For seal I use rabbet joints and good wood glue, then go around all cracks on the outside with bodyfill (bondo), and silicone on the interior. I'm a bit anal when it comes to the cabinets though.

Iron on veneer is easy to use for a beginner, but I'd recommend non-backed veneers and contact cement for best results (and it's cheaper)...

Depending which speakers you build, lots of kits include the options for cabinets. The Ar.com DIY's, for example can be bought from madisound.com with cabinets and crossovers pre-made by madisound...there's some good subs that can be purchased with pre cut cabinets as well.
.