Amp Questions...BAMTM

[Keefe]

I'm building this:

http://www.zaphaudio.com/BAMTM.html

And I need something to power them. After a little research I have determined that an integrated amp would be the best/cheapest option. I found a reasonably cheap NAD integrated amp that does 50Wx2 and right now that seems like my best option.

I'm building the vented enclosure (2ft^3) and it's going in a college dorm room. My question is how much power these speakers can handle. Is 50W too much, too little, or just right? Also if there are any cheaper solution out there, please let me know (the NAD is $300).

My other question is to do with building the enclosure. On Zaph's website it says to stuff the bottom with packed dacron fiber. I have no idea what this is but was looking at the Acousta-Stuf Polyfill at Parts Express. Is this the right stuff?

[Jed]

http://www.htguide.com/forum/showthread.php4?t=26752

The above should answer some questions about amplification.

Dacron or Acousta Stuff is fine.

And welcome to the Forum :T

[---k---]

if you're on a budget, the NAD will probably work well. there are a lot of options out there, some may be better than others, but the nad will work well.

dacron fiber is like pillow stuffing from the fabric store or wallmart. The PE acoustic stuff is better, but small. For you, the difference between $5 and $30 may not be worth it. Up to you and your budget. Regular pink fiberglass will also work well. the price is somewhere in between the two.

[Keefe]

Thank you for all the help. One more question though

How much deadening should I buy? I need to get Sonic barrier for the top but it only comes in 18x24" sheets. I figure that is enough for only 2 sides so I should get 4 sheets total to cover everything (and you don't need to deaden the backs of the baffle, correct)?

And 2 1lb bags of Polyfill should be fine for both bottoms (or do I only need 1?)

Thanks again

[Jed]

I figure that is enough for only 2 sides so I should get 4 sheets total to cover everything (and you don't need to deaden the backs of the baffle, correct)?

And 2 1lb bags of Polyfill should be fine for both bottoms (or do I only need 1?)

Thanks again

I'd use the thicker Sonic Barrier on all the walls except the front baffle, and that's all you really need for a ported enclosure. For a sealed, yeah a combination is nice with Acousta Stuff. See Zaph's recommendations:

http://www.zaphaudio.com/whispermat.html

[---k---]

Looking at Zaph's site, these are a budget speaker. It appears that most of his recommendations are aimed at budget minded people. I believe that he recommends the foam for only the top half of the speaker. If my math is correct, the top half of each speaker will need 1 1/2 sheets of PE Sonic Barrier. So 3 sheets total. Remember that your corner will overlap, and you can hold it back a hair at the front baffle.

For the bottom half of the speakers, he recommends just fill. I ran upstairs and pulled a bag our pillow stuffing out of the closet. It was a 12oz bag, so less than a pound, and it was about the size of a normal pillow. So, 1 bag per box will probably be about right to fill the bottom of those.

Putting the SB on the bottom half also would work great. And if you did this, you wouldn't need the fill. It is tradeoffs between cost and budget. With these drivers and crossover, I think Zaphs recommendations are right on target.

[dawg1161]

Could one use carpet pad?

[Jed]

One potentially good cheaper material is 1/2" thick carpet padding. The thick felt kind is almost always good, and you can double it up if you need more damping. The chopped foam type can be acceptable also, although the acoustic properties of this can vary. You will have to test it. You can almost tell how well it's going to do by just putting close to your ear while listening to pink noise. Just be aware that there is a wide variety of carpet padding, and a lot of it does not absorb well enough. My advice, unless you're building ultra-cheap speakers, stay away from carpet padding.

Above is a quote from Zaph's site about carpet padding.

[Gir]

Food for thought, if you want a receiver that will last you well into the future, the Yamaha receivers have great value. The new RX-V661 is great at it's price. It has built in 7 x 105W amp .7% THD, 7 x 90W .06% THD. It's got 2 HDMI in and one out (sadly no analog to HDMI conversion), plus all the other usual connections. It sounds great, but a little on the bright side (how I like it actually). This receiver runs around $500, but I snagged mine for $400 at Tweeters. They might still have that sale going on, but the RX-V659 (661 replaced that) actually sounds a bit better, but doesn't have the HDMI, but is $400 (maybe less now). Both of them get good reviews all around.

As for how much power to pump into it, 50W should do just fine. You're going to need to be careful about over-excursion. Those drivers have 4.25mm xmax, so running them without a sub could push them a little too far pretty quick.

[Keefe]

I might be wrong, but I don't think that receiver can handle a 4ohm load. If it could, I would be all over it (well maybe not that one...too expensive). I was originally looking at some $300 Denon stuff but they can only handle 4ohms at very low volumes without overheating.

One more question:
what is a good crossover location? Should I just stick it in the bottom (maybe with a little covering to protect it from the polyfill?

[Gir]

I might be wrong, but I don't think that receiver can handle a 4ohm load. If it could, I would be all over it (well maybe not that one...too expensive). I was originally looking at some $300 Denon stuff but they can only handle 4ohms at very low volumes without overheating.

They can handle a 4 ohm load just fine, but you need to make sure you put that into the settings before you fire it up. The manual claims it's important