Building a Dinner Theater w/ DIY Speakers, Subs, etc... - Page 8

was just by there today.

So I just checked out your pictures on your first page. Looks like most of the stone siding is up, looks really nice. Also, I really like how you've finished off the speakers, they're actually rather pretty. I wouldn't have thought of painting them gray but they're pretty stunning in that color. How did you apply the paint, with a brush or spray? Also, did you route the edges on the 1 PIs? When the theater is complete will you be able to see the 1 PI speakers or will they be hidden? I think hiding them would be a bit of shame!

Nice thread. I've been on here (lurked on here) for years now. But hadn't seen this thread yet.

Being from DSM, I'll have to check this out some time.

Just saw you question today and thought I would weigh in. I have an Onkyo 805 and find that it runs very hot...but not from the amps. In my experience it is the digital processing that generates a lot of the heat, as it runs hot even when used as a preamp.

My solution was to purchase a componnet cooling fan (http://www.coolerguys.com/compcooling.html) for $65.00. It runs nearly silent and I just plug into the switched power plug on the back of the receiver. I have used it for 5 years without any failures and it keeps the Onkyo quite cool. There are numerous options on their website but I bought the Comcool Dual 120mm Component Cooling Stand as it looked decent and could be used with a temperature controller (which I never used).

I have no affilation with Coolerguys and there may be better/cheaper alternatives available, but I know that I haven't thought about excessive heat since adding the twin fans.

Through that area.

Are the amps built like servers - cool into the front hot out the back?
Where will the rack be installed?
If you can seal off the back i'd install a separate exhaust fan on the back side that pumps air out of the space - maybe into the HVAC system.

That said, I'd eliminate the top fan blowing hot air back into the front space.
And starting from the top, I'd install:
8 amps
2 power strips
Oppo bluray player
1RU blanking plate
1RU fan unit (check the alignment with vent holes on the receiver - would be nice if same depth)
4RU receiver
2RU fan unit

Cool project. My thoughts on the rack, if the amplifiers do indeed pull in from the front and vent out the back, the exhaust fan will need to be able to move an amount of air equal to or greater than the sum of all the amplifier fans. If it does not it will actually restrict airflow out of the cabinet area. Having an opening at the top with the additional inlet fan at the bottom would be a better solution IMO if the exhaust fan does not meet the criteria.
If possible I would suggest to do a remote fan ducted to the top of the enclosure area. Again, the fan would need to move more air than the amplifiers and I would leave an open area at the bottom.

Behringers airflow is from the rear to the front. Why? I don't know. It seems counterintuitive. And there is even a filter on the front AFTER the air passes through the amp. Doesn't make much sense to me.

It's called poorly copying someone's design.

It seems to work well enough. I've never had any problems yet.

Very nice...

ETA on first fire-up?

JSS

Stack O Crowns....very excited!

Wow!

About the F20s....you said you were running music through them. Music rarely contains content less than 30Hz, so the F20 can take all 500W without reaching Xmax above 23Hz or so. Movies, on the other hand, will test the F20's limits.

Careful testing will reveal where those limits are. Using Soho54's Audio Test DVD's -0.5dB LFE tracks can really help, along with a careful gain structure setup.

Unless you highpass, the F20s will literally loaf all night above 23Hz, with clean bass, no compression worries. With 4 of them clustered, instant +12dB over one of them. You should be good. If for any reason you need more headroom, you can use more power and highpass for an extra 3-5dB, but then you are running them near the edge.....

I think it best to limit the content they get to 20V maximum below 25Hz, and above 25Hz to 30V maximum. 30V is 300W. You are far from Xmax, and within your amp capabilities. 30V at 17-20Hz will exceed Xmax, and may near Xlim, causing clanking and possible damage.

Remember, it is always best to run at least 3dB from limits, and 6dB from limits is even more preferable.

Good articles about cinema sound:

http://www.hps4000.com/pages/articles_page_.html

Good 1st read is the "If they knew what you were missing" article.

HPS4000 really doesn't output much below 35Hz, so take that into account when reading. The horn loaded subs are tuned to 40Hz, but the systems have enough headroom that sound would nonetheless be pretty impressive. When HPS4000 was conceived, films rarely dug below 40Hz. But the articles are worth reading.

Even is you have to run below reference in practice (remember, reference level is LOUD, no one speaks at 75dB in normal conversation, except maybe Drill Instructors), running with enough headroom to present cleanly is a must.

JSS

Having more power than you need AKA headroom is the way to go IMO, but having the discipline to not push things too far will be required. OTOH regular clipping form an underpowered setup will COOK a woofer in short order, again discipline is key.

Having 3dB headroom is double the power in reserve...

How loud do you want to get? Seriously - too loud can be a problem too.

Spending $200 to save you from clipping you'll likely never hear to gain headroom you'll likely never need seems to be a waste IMO.

More power can cook coils that much faster (assuming an unclipped signal and higher drive levels).

Honestly - if you have your system set to deliver near reference level SPLs, it will be too loud for most people. 4X F-20s will do the better part of 125 dB at a meter, groundplane, with 100 watts to each.

That's reference + 10 dB. Sure - that's at a meter, but it is groundplane, and my actual measurements back that number up.

Reference level is -10 dB from this, so it only takes 1/10th the power. That's 10 watts/cabinet, meaning you have a lot of headroom built in already.

You need reference for peaks, actual levels will likely be reference -10 dB as an average, maybe even lower.

So - that's about one watt to each cabinet. Your 350 watt/channel amps are plenty big. Though it is a little more complicated than this, you've got about 349 watts of headroom from where you'll likely be running things. The difference between 349 and 499 watts of headroom is not that significant, it is less than two dBs....and with the 350 watt amp, you're at 25 dB of headroom already.

Relax.

Save your money.

Enjoy the lower power bill.

I have only read a few of the first post, but I really enjoyed the LilMike F-20 thread and seeing you going into somes detail with those has drawn me in.. subscribed. Overall, it sounds like a great project to undertake. Looking forward to getting caught up with the thread - thanks for sharing.