Zaph Budget Alu MTM | IDQ15 HT/Music Build Log

[Suprchargd]

Hello all,

Just found this site two days ago. Already logged at least a dozen hours on here just reading away. I've never been impressed with the HT-in-a-box systems I've heard, and I've always been meaning to do my own HT setup.

Unfortunately I'm a college student, so I'm basically broke. I've decided to go with Zaph's BAMTM design to do a 2.1 setup for my basement due to the low cost and the relatively simple design of the box. The only modification I plan is to do a floor standing tower instead of using speaker stands.

My previous audio experience is limited to head unit and speaker installs, and the typical sealed and bass reflex subwoofer boxes. My first "system" consisted of a Panasonic HU and Pioneer 6.5 coaxes in my first car.

I already have an Image Dynamics IDQ15 D2 in my possession, and just ordered a Bash 300w plate amp (on sale today for $99). I plan on building a large bass reflex enclosure for the IDQ, tuned low. Hopefully going with a large box will negate the need to EQ it. Using WinISD I'm thinking of going with somewhere around a 6.5 @ 24Hz design. I have space to corner load the sub, but I was thinking I might make the box longer and shorter and use it as a desk, placed in between the two couches? Still undecided about that.

Anyone have amp advice for the BAMTM's? I saw a post from an earlier thread mentioning the Behringer A500 (http://www.partsexpress.com/pe/showd...number=248-749) from Parts Express, which currently costs $200. Any lower-cost alternatives within the same power range?

Can anyone point me to a thread or link describing how one can make a home-made jasper circle jig?

Also, I've noticed a majority of the time home audio users don't follow the 15-18 sq. in. port area per cubic foot rule as in car audio. Any reason why? How are you not getting port noise? I think acceptable port velocities should be between 50-80 m/s if I remember right, wouldn't the small ports easily exceed this?

[Mazeroth]

Here's a $129 shipped alternative to the A500 Behringer. Granted, it doesn't have as much power and I've never heard one but I have heard good things about it:

http://emotiva.com/bpa1.html

PE sells a Dayton version that's similar for more coin and not as fancy looking:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-812

[Suprchargd]

Hmm your first link takes me to a HT projector, not any amps. The Dayton is considerably less powerful, I don't think that is enough power to really make the speakers show their true potential. I might have to just splurge for the Behringer if I don't find another alternative.

[Mazeroth]

I fixed the link, sorry.

Either amp will give you 75w/channel @ 4 ohms which should be pretty much all the power you would need. However, having reserve power is a good thing so springing for the Behringer is not a bad idea, either. It just depends on your application.

[Suprchargd]

I'm being hopeful, but maybe PE will have an xmas sale and the Behringer might come down a bit in price. We'll see.

Need to call up my friend and see when he can loan me his van so I can go buy a few sheets of MDF.

I'm still trying to decide whether to build the sub box first, or the towers.

[ThomasW]

I'm being hopeful, but maybe PE will have an xmas sale and the Behringer might come down a bit in price.

Highly unlikely Behringer recently increased pricing on these. And given the issues with copper, other metal and fuel costs, if anything prices will continue to go up.

If you check the prosound online stores frequently you can find refurbished units..

[---k---]

I would build the sub first. They are an easier first project.

For an amp, you didn't mention what receiver you were using. If it is any good, I would just stick with that until your budget allows for more. My Pioneer 1015TX ran my big Khanspires just fine, and the impedance dips pretty low. Spend the $200 on more or better speakers than the amp. (Though, the BMTM are likely great, not knocking them) At least for now. If you really want an amp, the Emotive or A500 is the best you're going to get new. Check used at your local shops and pro shops. Shipping will kill you on ebay, etc...

To answer your question about port noise, just use Unibox (prefered) or WinISD and make sure your port speed is reasonable. The lower the frequency the port speed gets up there, the less it really is an issue. On my big sub, the port speed is nothing until less than 20hz, where is skyrockets. But at 18hz, who cares... Flared ends go a long way. Using a router and a big round over bit (3/4" or greater) on a 6" or bigger port works great.

There was a discussion here once of homemade jigs, but it was within another speaker conversation, and I'm not sure where. You're going to have to search deep, unless someone else remembers where.

[69Stingray]

http://www.woodworkingtips.com/etips/etip102000sn.html

[Sefferdog]

Can anyone point me to a thread or link describing how one can make a home-made jasper circle jig?

http://www.htguide.com/forum/showthread.php4?t=27028&page=1&pp=35

Dig through this thread, there are a couple of links to DIY circle jigs. :T

[Suprchargd]

Thanks for the links guys.

For an amp, you didn't mention what receiver you were using. If it is any good, I would just stick with that until your budget allows for more. My Pioneer 1015TX ran my big Khanspires just fine, and the impedance dips pretty low. Spend the $200 on more or better speakers than the amp. (Though, the BMTM are likely great, not knocking them) At least for now. If you really want an amp, the Emotive or A500 is the best you're going to get new. Check used at your local shops and pro shops. Shipping will kill you on ebay, etc...

I'm actually thinking of not going with a receiver. I'm building a HTPC with an Antec NSK2480 ($50 on sale the other day ), I figure I can just use a sound card to handle any equalization duties. Hence why I was looking for an amp to drive the MTM's. Anyone see a problem with that? I didn't read anything yet that says I can't do this, but than 100% of the threads I've seen so far people have had a receiver of some sorts. The HTPC section of the site seems a bit dead.

[Suprchargd]

If I'm going with a down-firing sub, how much space do I need from the sub to the floor? I picked up a set of PE's spike feet (http://www.partsexpress.com/pe/showd...number=240-716) but I don't know if that is enough clearance. Opinions?

[ThomasW]

Hopefully going with a large box will negate the need to EQ it.

EQ is need to tame room induced issues

Using WinISD I'm thinking of going with somewhere around a 6.5 @ 24Hz design

That Fb is way to high for HT, you want 18Hz or so, that way there's less worry about the driver unloading below Fb.

I think acceptable port velocities should be between 50-80 m/s if I remember right, wouldn't the small ports easily exceed this?

We target a much lower Mach number, 20m/s is good target

If I'm going with a down-firing sub, how much space do I need from the sub to the floor?

3" minimum

[---k---]

I'm actually thinking of not going with a receiver. I'm building a HTPC with an Antec NSK2480 ($50 on sale the other day ), I figure I can just use a sound card to handle any equalization duties. Hence why I was looking for an amp to drive the MTM's. Anyone see a problem with that? I didn't read anything yet that says I can't do this, but than 100% of the threads I've seen so far people have had a receiver of some sorts. The HTPC section of the site seems a bit dead.

I'm not sure that a sound card will have enough drive voltage to on the line out to go directly to the amp. That it why you typically need a preamp in front of the amp.

Bikedavid currently has a thread discussing this issue trying to drive a proamp.