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Topic Review (Newest First)

02-27-2012 06:04 PM

cxa0897

Re: Home Theater Sub Build

mag 12 v3. kinda sql sub. still gets pretty damn loud. great sq when i had it in a sealed box, which ill use in my room just to save space

02-27-2012 05:58 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by cxa0897

si mag. takin it out of the car and into the ht once my 8s come in

Oh. What model is that?
I heard Stereo Integrity has real good sound quality.

02-27-2012 05:48 PM

cxa0897

Re: Home Theater Sub Build

Quote:

Originally Posted by DankNuggz

Thanks man.

....Huh?

si mag. takin it out of the car and into the ht once my 8s come in

02-27-2012 05:33 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by cxa0897

I'm loving that amp box.

Thanks man.

Quote:

I might do that one my mag gets the honor of taking over my ht duties.

....Huh?

02-27-2012 04:36 PM

cxa0897

Re: Home Theater Sub Build

I'm loving that amp box. I might do that one my mag gets the honor of taking over my ht duties.

02-27-2012 04:05 PM

DankNuggz

Re: Home Theater Sub Build

Bought a flat screen wall mount from Amazon for $55.
Looks like the ones Best Buy sells for $200-300.
Cheetah Mounts Plasma LCD Flat Screen TV Articulating Full Motion Dual Arm Wall Mount Bracket For 32-65" Displays Up To 165LBS Black With 10' High Speed HDMI Cable With Ethernet Fits Up To 24" Studs

I think my next project is to buy a HTPC case so the computer can go in the entertainment cabinet.--------Built that too a few years ago.
Then I'll build a twin brother for the Kappa.

Can anyone recommend a different subwoofer that would go good with this design?

02-27-2012 04:04 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by Burkem_10

Wow that box looks nice! As well as the amp box, of course.

Ive got the same sub laying around at home and it doesn't even have that trim ring so idk.

Thanks man. I might build a grill for it, or just buy a new sub eventually.

02-27-2012 03:55 PM

Burkem_10

Re: Home Theater Sub Build

Wow that box looks nice! As well as the amp box, of course.

Ive got the same sub laying around at home and it doesn't even have that trim ring so idk.

02-27-2012 03:50 PM

DankNuggz

Re: Home Theater Sub Build

GOT THE BOX DONE!!!!!!!!!!!!!!!!!!!!!
Overall, I'm impressed with finish, the design, and the sound.
Eventually, I may try some polishing compound to try to mirror the finish a little more.
I've had the sub in a pre-fab Bassworx box 1.65cf tuned to 42hz since I bought the plate amp, and it sounded better than my 10" Cerwin Vega.
Put the sub in the new box, and WOW!! what a difference.
I'm feeling notes that I never knew were there. The SA240 really pushes the sub to its limit.
It doesn't shake the walls down, but its more than enough for my condo.

When I pulled the sub out of the old box, a piece of the trim ring came off. D'oh!
I have a blown Kappa, Does anyone know if I could use the trim ring off of that one for this one? Could this be done easily?

Heres some pics.

02-22-2012 06:17 PM

DankNuggz

Re: Home Theater Sub Build

Got the amp box finished!!!

02-14-2012 05:40 PM

DankNuggz

Re: Home Theater Sub Build

Got some more pics.

Made some feet for the boxes.
Ordered some rubber feet that I will inset into the feet that I made.

Spray painted them with stainless steel spray paint.

The big feet will go on the sub box, and the little feet will go on the amp box.
I think the feet on the amp box might look funny---if it does, I'll just use the rubber feet.

02-14-2012 05:31 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by smcfab

Nice!

Thanks man!

02-13-2012 07:39 PM

smcfab

Re: Home Theater Sub Build

Nice!

02-13-2012 02:28 PM

DankNuggz

Re: Home Theater Sub Build

My ghetto hoist.

02-13-2012 04:12 AM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by BigBird

looks really good man! one question though any reason you didnt put the amp in the sub box ? i always thought this was done to help keep the amp cool much like a ported box dose with voice coil's on sub's.

I did it like that for a few reasons.

The original design from andrew @ audioholics does not use a plate amp,
it uses a Behringer EP2500 to power two of these.
So, eventually I will build another.
I wanted the flexibility of changing amps out, and for a future EP2500 or EP4000.

Also I would think, just like with car amps, you shouldn't mount your amp on or in the box because of the vibrations.

02-12-2012 08:03 PM

BigBird

Re: Home Theater Sub Build

02-12-2012 06:46 PM

smfonic1

Re: Home Theater Sub Build

That thing looks really good.

Good Job!

02-12-2012 06:31 PM

DankNuggz

Re: Home Theater Sub Build

Some more pics.

A couple coats of clear lacquer on the amp box.

I'll sand some more and add a few more clear coats to try to give it more depth and try to get the "orange peel" out.

Overall, I'm happy with the finish. I don't think its going to be a "mirror black"
but more like a gloss black.

02-08-2012 08:04 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by weshole

Still looks awesome.

Thanks Man!

02-08-2012 06:36 PM

weshole

Re: Home Theater Sub Build

Still looks awesome.

02-08-2012 06:20 PM

DankNuggz

Re: Home Theater Sub Build

Finally got a chance to put it in the spray room.
We've been busy at work, so I can only work on it in between jobs when the
spray room is empty.

A couple coats of black, and filled imperfections w/ spot filler.

Sanded it, and put another coat of black on.
You can see where I messed up on the port. I rounded over the port, before I
put the second front baffle on. Had to bondo it and an orbital sander wouldn't fit
in the port hole, so I had to hand sand all of it.
Hopefully, it won't be so noticeable once I get more coats on.

More black, and more spot filler.
The port looks a lot better now.

01-25-2012 04:32 PM

DankNuggz

Re: Home Theater Sub Build

Got the box sanded and ready for the spray room, also built a box for the amp.

Put a coat of black on and some spot filler. Will sand and put a few more coats of black before I clear coat it.

01-25-2012 04:26 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by Fallen

That's coming together nicely. Really professional looking. Great job!

Thanks dude. This is actually the second box I've ever made. Being a Cabinet Maker helps out a little though.

01-24-2012 08:33 PM

Fallen

Re: Home Theater Sub Build

That's coming together nicely. Really professional looking. Great job!

01-24-2012 08:02 PM

DankNuggz

Re: Home Theater Sub Build

Quote:

Originally Posted by smcfab

Hmm, mine went into protect right away with 3+ ohms, and 294 watts?

Maybe I got 2 bad units?

PDF to large, so I'll just copy and paste.

PE #300-804 200 Watt Sub Amp: A closer look
by Darren Kuzma
The Parts Express #300-804 is one of the more recent arrivals onto the subwoofer
amplifier market. With a very modest external package, it is difficult to get a good idea of
what the real-world performance of this amplifier really is. After receiving many inquiries
into what makes this amplifier different from others on the market, I decided it was time
to take a closer look at what it has to offer.
General Description
The amplifier is fairly compact and measures 9-13/16” square on the face, and 5” deep.
This depth includes a plastic rear housing which surrounds all of the electronics to
prevent air leaks into the cabinet and to protect the components. The cutout size
needed to install this amp into a cabinet is 8-5/8” square. The amplifier weighs in at a
healthy 12 lbs. Construction isn’t exciting on the inside, but it is a very functional design.
On the inside, the only thing that stands out is a pair of large 10,000 uF power supply
caps. The 1-1/2” tall heatsink fins on the outside hint that it should be good at removing
heat from the output transistors.
Power
Before we start throwing power numbers out there, we must first discuss one of the
main features of this amp: the soft clip circuitry. This circuitry prevents the amplifier from
clipping, eliminating the audible flops, farts, and wubba-wubba’s that are normally a
result. Amplifier clipping is probably the most noticeable form of distortion that can come
from a subwoofer system, other than physical bottoming of the subwoofer driver. Not
only are these ill-effects of clipping bad-sounding, they can also cause damage to
subwoofer drivers or to amps themselves.
The soft clip circuitry works by adjusting the entire output such that none of the sine
wave peaks are “chopped off”. While it does take a certain amount of time for this
circuitry to kick in, it is in the low millisecond range and for all practical purposes works
extremely well. Some people may feel gypped because the circuit is essentially
compressing their audio signal, but is a small price to pay for protecting your ears and
your sub!
Back to the power testing… Since most amplifiers do not have this soft clip circuitry, as
the output level is increased the signal begins to clip and massive distortion sets in.
Hence, many amplifiers will often be rated max power at 10% distortion or some other
very high percentage. But, because of the soft clip circuitry, this amplifier is always
working in its low-distortion range of less than .2%, even at its maximum measured
RMS output power.
By using a classic power testing method with a scope and a true RMS voltmeter, I was
able to measure the power output into various dummy loads. Into a 4 ohm load, the
amplifier was able to maintain 31V RMS without clipping. This corresponds to a power
output of 240 watts. Into 8 ohms it measured 34.5V RMS, or approx. 150 watts. At 16
ohms, voltage was the same at 34.5V RMS, or 75 watts.
Frequency Response:
By running measurements of the amplifier into a dummy load, I was able to get a good
picture of the overall frequency response of the amp. The stock amplifier has a
response that is 3 dB down at roughly 18 Hz on the low side and 168 Hz on the high
side when the crossover is at its highest setting. A range of 18 Hz through 160 Hz is
appropriate for just about any conventional subwoofer system.
The low end:
A built-in “rumble filter” attenuates the lowest audio frequencies to help conserve
amplifier headroom and protect drivers. The “rumble filter” is actually a 12 dB/octave
high-pass filter that is centered at 20 Hz, the F3 is 18.2 Hz. Since most source material
does not contain information below 20 Hz, usually we are not missing anything. But, in
cases where information is available this low, we generally need to protect our drivers
from this potentially damaging information. Since excursion demands increase with
decreasing frequencies, even the beefiest sub can start to run into overexcursion
problems. This is particularly a concern in vented subwoofer systems where
overexcursion occurs rapidly below the tuning frequency.
The high end:
The upper end low-pass filter of the amplifier can be adjusted from a frequency of 40 Hz
to 160 Hz. The settings on the knob are actually fairly accurate and correspond with the
upper end Fc quite well. The low-pass filter features 24 dB/octave attenuation, far
superior to standard 12 dB/octave filters.
Side commentary: There are several problems associated with the common 12
dB/octave filters found on other amplifiers. The shallow slope often does not allow good
integration with mid-sized main speakers. It is difficult to achieve a good transition
without getting overlap in the lower midbass region, which can cause a tubby or boxy
sound. Also, many subwoofers have large response peaks in the 800 Hz- 2 kHz region.
If not attenuated enough, these peaks can “bleed through” into the output from the
subwoofer, causing what could be described as a “ringing” sound. Not only is this
annoying, but it can result in a fatiguing system and a subwoofer that does not
“disappear” into the room.
Connections
The #300-804 has a full complement of the standard connections needed for most
subwoofer applications. Power is supplied via a standard 6-foot power cord. A signal
can be fed to the amplifier from either the high-level (speaker) input or a low-level (line)
input. Output to the subwoofer is through a single pair of speaker wires, terminated in
female disconnects. The disconnects can be cut off and the wires stripped for a direct
connection to your driver.
When the speaker level inputs are used, the speaker level output will transmit the signal
to your speakers with the addition of a high-pass filter. The high-pass filter consists of a
220 uF electrolytic capacitor and corresponds to a crossover point of approximately 90
Hz @ 8 ohms and 180 Hz @ 4 ohms. The capacitor can easily be removed or the value
changed if desired. The speaker level input posts will accept bare wire, or by removing
the small plugs at the end of the posts, banana plugs are accepted.
The low-level RCA input features stereo connections, allowing both left and right
channels to be connected to the amplifier. The left and right channels are summed
internally and both are fed to any single coil subwoofer. Either channel can be used for
connection to a mono subwoofer signal. The low-level line out transmits the complete
audio signal that is entering the amplifier. There is no high-pass or low-pass circuitry
implemented in this feed, therefore the full range of original signal will pass through.
This feature can be used when “daisy-chaining” multiple subwoofer amplifiers.
Auto-on circuit
The auto-on feature of this amplifier allows it to automatically turn itself on and off as
needed. The auto-on circuit is activated via the input from the speaker or line level
inputs. The turn-on sensitivity through the line-level inputs is approximately 5 mV, which
is very low and should trigger with even the faintest signals. Once a signal ceases to be
sent to the amplifier, it will take roughly 30 minutes for it to turn itself back into off status.
This extended shut-off time is designed to prevent the amplifier from shutting off during
periods of inactivity in movie soundtracks. When the amplifier is in “standby” mode, the
power indicator LED will be completely off.
Protection circuitry
The #300-804 amplifier features a triad of protection circuits that make it very durable.
As mentioned previously, soft clip circuitry is implemented to protect the driver and
amplifier from rapidly changing dynamics. Not only does this make the amplifier sound
better, it also makes it operate in a much more stable manner, without putting extra
strain on the power supply.
A very effective thermal protection circuit automatically cuts off the output of the
amplifier should the heatsink become too hot. Because high temperatures are what
destroy amplifier components, this feature ensures that unsafe conditions are never
reached. After the thermal protection has been engaged, the amp will automatically
reset itself once it reaches a cooler and safer temperature. There is no need to
manually reset anything on the amplifier-- it will turn on back to its original level once it
is cool. However, should the thermal protection circuit repeatedly trip, it is usually
indicative of other problems such as low driver impedance or poor circulation.
Lastly, the amplifier is fully overload and short-circuit protected. Should the output wires
of the amp ever touch each other or a driver “melts-down”, the amplifier will go into a
protection mode, indicated by a red power LED. This does not indicate damage, but
merely that the amp has entered a state of self-protection. Should the amplifier enter
this mode, it will need to be unplugged for 30 seconds or so to allow the circuit to reset.
I decided that to do a full evaluation of this unit, I would have to test this short-circuit
protection. While running a sine wave at full power of 240 watts into 4 ohms, I directly
shorted the output wires of the amplifier. Besides practically welding the wires together,
the amplifier immediately went into its protection mode like it should. Sure enough, after
unplugging and plugging the amp back in, it went back into normal operating mode and
was working just fine.
Let me tell you, for all the testing I put this poor amplifier through, it kept going without
any problems. I never even blew the fuse-- truly a testament to its well-designed
protection schemes.
Load Stability
One of the problems often encountered with other subwoofer amplifiers is their lack of
stability into difficult 4 ohm loads. To get an idea of the stability of this amplifier, I
decided that the best test would be to run it into a 2.66 ohm resistive load. This
represents a more difficult load than anything that will be encountered with a normal 4
ohm nominal driver. To make the test as grueling as possible, a 100 Hz pure sine wave
was used as the input signal. Running pure sine waves is about the most destructive
thing that you can do to any amplifier. Since most subwoofer systems see only
occasional output at full power, this is much more rigorous situation than will be found in
normal use.
So, running at full power of 294 watts into 2.66 ohms, I wanted to see how long the
amplifier would last. Starting from room temperature, it ran for approximately 6-1/2
minutes before shutting down. The thermal protection kicked in at this point and put the
amplifier back into standby mode. Once it cooled down, the amplifier picked right up
where it left off and continued playing. Obviously since the amplifier was already hot, it
didn’t take too long to go into thermal overload again. However, it is good to see that it
can last even this long, and that the protection circuits are working very well. 6-1/2
minutes of straight runtime at full power into 2.66 ohms is really quite impressive. A
standard 4 ohm subwoofer should be any easy task for this unit.
As a contrast, when the #300-794 amplifier was run through the same test at the same
294 watts of power it only lasted 4 minutes. On top of that, I found that a blown fuse was
actually responsible for shutting the amp down, and not any of its protection circuitry.
Hence, if this occurred in a real listening situation, you would have to stop the movie,
pull the sub out and meticulously replace the fuse-- obviously not an ideal situation.
Power consumption
In the interest of learning as much as possible about the amp, I decided to do some
quick tests of the power consumption. At full power, it uses about 540 watts, which is a
current draw of about 4.5 amps. When turned on, but no signal is present, it uses 17
watts of power. When in standby or sleep mode, 15 watts of power are dissipated.
Conclusions
While this amplifier may not have quite the raw power of some other sub amps on the
market, it more than makes up for this with consistency, stability, and great sound
quality. Compared to the 300-794 and similar amplifiers, the maximum SPL the 300-804
can achieve will be within 1dB, which is more or less an unnoticeable difference. The
soft clip circuitry is an extremely valuable advantage of the #300-804, and will surely
result in a cleaner sounding sub. To me, the peace of mind of having a nearly
indestructible amplifier alone gives this item great value. Add to that the great low
impedance stability, small size, and great price, and this amplifier is a winner!
Specs:
Measured Power: <0.2% distortion
240 watts RMS @ 4 ohms
150 watts RMS @ 8 ohms
75 watts RMS @ 16 ohms
Amplifier Frequency Response
3dB down points (highest XO setting): 18 Hz and 168 Hz
Rumble filter response: F3 = 18.2 Hz, F6 = 13.7 Hz, F10 = 10.7 Hz
Low-pass frequency: Continuously variable from 40 to 160 Hz
Output Frequency Response
Speaker level: 6 dB/octave high-pass, 90 Hz @ 4 ohms, 180 Hz @ 8 ohms
Line level: 10 Hz- 20 kHz, full bandwidth
Auto-On Sensitivity
~ 5 mV, 30 minute shut-off time
Max Power Consumption
540 watts, 4.5 amps

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