Pro Audio Power Amp/Home Audio Preamp

[Kenwood Man]

Question for you guys, I am building my own home theater mega sub enclosure. It is definitely in Tim Allen Style. I am using two Digital Designs 9918’s they are 18 inch with a 5000w RMS ratting: http://i17.ebayimg.com/02/i/000/db/e2/00a7_1.JPG
I also bought a Crown Macro Tech 5002VZ to power them: http://i22.ebayimg.com/02/i/000/de/51/e033_1.JPG
Can I use one of the outputs from my McIntosh C-32 preamp with a low-pass filter on this amp? Obviously this has the typical 1/4 inch input/and output’s that all pro audio has so what is the best way to integrate this into my system? Just use quarter to RCA for the pre-in, and make my enclosure with 1/4 inputs?

Thanks for your time! Now I'm sure that I appear to be insane, just understand that it was a fun project designed to blow the neighbors away.

[Clmrt]

According to the manual, output is via 5-way binding post, so any typical speaker cable should suit.

Headroom - wow!

[whoaru99]

Were you planning stereo subs or a mono sub?

If mono, you'll need a summing network before the amp to combine the L/R preamp channels so you get the bass from both channels to the sub.

RCA to 1/4" cables, or RCA>1/4" adapters should work fine between the pre and amp.

Also, I wouldn't use 1/4" jacks between the amp and the sub. I'd wire with the binding posts on the amp and maybe use Speakons or more binding posts on the sub cabinet(s).

[Kenwood Man]

I am thinking that I will run it mono that way placement is not an issue. What do you guys think? Good idea on the binding posts, that sounds much better that 1/4's. I also for got to mention that these are dual voice coil subs. Each oil is rated at 3/4 ohm. Anyway I got a week off from school so I should be able to get this setup together and give it a test with Master & Commander. :banana: Ready for some cannon blasts! lol

[bobrown14]

I am thinking that I will run it mono that way placement is not an issue. What do you guys think? Good idea on the binding posts, that sounds much better that 1/4's. I also for got to mention that these are dual voice coil subs. Each oil is rated at 3/4 ohm. Anyway I got a week off from school so I should be able to get this setup together and give it a test with Master & Commander. :banana: Ready for some cannon blasts! lol

You probably need a summing active crossover between the pre and power amps as suggested. Rane makes a nice one with a sub out and the crossover freq is adjustable. RCA to 1/4 (mono TS is what they are called - tip sleave) to pre and 1/4 (mono ts) to AMP, then 1/4 mono ts to speakers if that's what the speakers have. Keep them short, I use 1 meter (3ft) cables with my crossovers.

Good luck,

Bob

[bolly]

gonna need a cabinet made of double 1" MDF on all sides kenwoodman, monstersub, huzzah!!1! :thmbsp:

[whoaru99]

Some use 1 layer of "baltic birch" plywood and 1 layer of MDF. Plywood on the outside, MDF on the inside, I think.

Lots of internal bracing too.

[bowtie427ss]

I also for got to mention that these are dual voice coil subs. Each oil is rated at 3/4 ohm.I have a couple questions.

Are you at all familiar with the 5002VZ, it's limitations, or it's AC mains power requirements to deliver full power at low impedance loads?

How do you plan to wire the drivers/load the amp?

[Clmrt]

Maybe JBL's BX63, as used with the B380 / 460.

[Kenwood Man]

I am going to have the amp wired to a dedicated 20 amp line so power should not be an issue. Plus if I wire the dual coils in series I get can my ohm load up to 1.4. Thanks for the info on the cabnet materials. I figured it would have to be pretty over engineered inorder to survive. I will keep you all up to date as this project progesses. I got the 5002VZ for a really good deal so I couldn't pass it up.

[bowtie427ss]

I am going to have the amp wired to a dedicated 20 amp line so power should not be an issue.Just an FYI, 5002VZ draws over 40 amps at 50% duty cycle driving a stereo 4 ohm load, expect that figure to double with another halving of load impedance at which point it's nearly impossible to supply the current demand to produce full power.

The big macro's are fairly reliable and sound fairly good for their massive power output, they tolerate low impedance, and variable impedance loads exceptionally well.

Their strongest point is their ability to damp/control large/high excursion woofers in ported enclosures, even when several 8 ohm units are paralleled to create combined loads as low as 2 ohms.

Note that Crown does not give ratings or suggest nominal loads below 2 ohms(with the exception of a 1 ohm rating for parallel mono operation), they merely state that the amp will remain stable when the impedance dips dramatically low.

The compromise is simply that these amplifiers require massive amounts of juice from the AC mains.

I seriously doubt that full power with a 5002VZ can be achieved with even a modest 8 ohm stereo load on a 20 amp household circuit.

My prediction is this: if you are going to run this in a typically wired home, you'll probably get the best performance by series connection of the VC's per driver, then parallel those two loads on the amplifier in parallel mono operation.

I don't remember 5002 intimately enough to know if it has the onboard ability to sum the channel inputs or not, it has a lot of front end flexibility including compressors/limiters and HP/LP filtering all onboard.

I would urge you to go to Crown's website and download the user manual and power/thermal spec sheet.

Just my .02 y'all understand....................

[Kenwood Man]

Thanks for the advice. I can always use the line I have for my welder. I have a seperate industrial line for my hobart welders, as I run a small fab shop out of my house. I can probably supply it 50amp from that box with no trouble, just have to make sure to isolate it from the welding as that puts a lot of noise into the line. I would rather get the info from you then make a stupid mistake. :)

[bowtie427ss]

Don't get me wrong, it'll run from a 20 amp circuit, you're just going to see clip/load limit lights coming on well below the amplifier's ratings. On probably 90-95% of your usage in a home it won't be an issue, i expect things like cracked drywall and broken knick knacks will be more immediate issues.:yes:

Not unlike your welders, those VZ power supplies impart their fair share of hash on the mains. Probably the most important thing to observe would be keeping it off the same leg of the AC as your source equipment. Again only becoming a serious issue as you start to get into the "throttle"......................... and i'm well aware that some of us like to do that from time to time.:D

I too run a relatively large Amp on subs, fortunately my sub amp is completely dual mono internally and has been converted to run from two 20 amp 120VAC mains supplies, stock configuation was for a single 30A 240VAC line.

PS i like your avatar, i'm rather fond of the 818 and it's little brother the 616, you'll find a few of those around this place.:thmbsp:

[Kenwood Man]

Thanks for your comment on my avatar, I really like my 818. I think the digital tuner section is just great. My 818 just recently started randomly shutting down a channel. I tested it and it appears to have a cold solder joint as all the components appear in spec. Ever have any issues with one of your Technics?

With regard to the 5002vz, considering what you said I will isolate it for sure as I don't want to add any interference to the line. I will let you know how this ends up sounding. These subs have Kevlar cones and the magnets are 350oz, so it should be pretty crazy.

[bowtie427ss]

Ever have any issues with one of your Technics?
Minor and typical issues only, dirty switches, pots etc. Probably the most major issue is with the cheap trim pots. It seems that either debris becomes embedded in the wipe surface or it breaks down so that stable adjustments become nearly impossible, i ran into this problem while trying to get DC offset under control. They're cheap to replace with better substitutes, but it's a time consuming labor intensive process as there are three pairs of pots involved in adjusting idle current and offset. Two pair are easily accessible, while the third pair is mounted on a "burried" board in such a way that there's a board above it with pass thru holes to allow adjustment with ease, but no further access. It requires major disassembly including removing the faceplate.

I do have one 616 with a tuner that's silent, hopefully it's a dirt/corrosion issue or a cold/fractured solder joint as i know very little about tuners. I've currently put my SA's on a back burner as i feel they'd benefit sonically from a general recapping, which i'll eventually get to as i continue to eliminate other planned projects and gear.

The 5002VZ should provide you with plenty of "bump", it'll be interesting to see which load configuration works best for you. Just don't try to drive those woofers with the amp in "bridged mono" mode as they don't recommend less than a 4 ohm load in bridged mono whereas they spec down to a 1 ohm load for parallel mono.