I'm so disapointed :( 0 output subwoofer :(

[Fryguy]

Just finally got around to measuring my subwoofer in my living room after living here for a few months.

90db at 60hz

Ascendant Avalanche 18" with 1400 watt behringer. 6.25 cubic ft sealed

http://webpages.charter.net/fryguy

I'm kinda mad that the output is so low ;(

[Nichol1997]

How big is your living room? Maybe there is a dip in the frequency response due to room interaction. What does it measure at other frequencies?

[Fryguy]

small living room, haven't measured other frequencies yet

[ThomasW]

Well you've got something setup wrong. That much power at 60Hz should blow you out the door.

[Fryguy]

Not really sure what could be wrong. Checked all of the basics

[ThomasW]

You've haven't posted any specifics about this sub on this forum, so we know nothing about it's design or construction.

Options are...

1)defective driver
2)driver miswired
3)defective amp
4) amp switches set wrong
5)wrong connectors to power amp
6) receiver doesn't have adequate sub-out drive level for the power amp. (this is frequently a problem, if the sub output level is all the way up, and there's still low output from the sub)

You need to run a nearfield sweep to make sure the driver itself is working properly.

[Mark K]

I have to agree with Thomas,

You're either measuring at a null or you've made an error somewhere in the chain. That's all there is to it.

What are you using to measure?

[Bent]

The level controls on your Behringer - are they anything less than cranked?
They may not be level controls, they might be input attenuators, therefore they would be "bottlenecking" your input levels. I'd confirm this straight away?

[Fryguy]

I turned them up to just below clipping levels, about 80%

Outputting correct amount of power, verified by measuring AC voltage output and using ohms law to get a rough estimate (using a DMM).

I'm using radioshack db meter (digital version).

My mains are peaking at about 95db @ 1000hz (some old audax bookshelves for the time being)

[ThomasW]

We need specifics.

Are you sure the VC's are wired in phase? How are you running the amp? Strapped? Bridged? Stereo? What is the receiver's sub output level setting? Are the mains set to small? Etc, Etc,

[Inu_Yasha]

We need specifics.

Are you sure the VC's are wired in phase? How are you running the amp? Strapped? Bridged? Stereo? What is the receiver's sub output level setting? Are the mains set to small? Etc, Etc,

Definately double check everything and make sure that the interconnect cable that you are using isn't the problem! I just replaced some of my interconnects to my sub and all of a sudden I had super powerful bass. I had to turn down my settings because of it.

[Fryguy]

ok details:

Receiver is set to +0, amp gain is as high as it will go before clipping (70-80%). Power output is pretty much correct, as verified by measuring ac output voltage with no load. Subwoofer is wired in phase, and sounds correct in general. Receiver settings are small mains, direct mode, crossover at 60hz. Avalanche is wired in phase, verified to be 4ohm with multimeter (2+2 in series). Amp is bridged mono.

[ThomasW]

The mains are really too small to have a 60Hz crossover point, might want to try 80Hz.

Whether they're wired in phase or out of phase, 2-2 ohm VC's in series will measure 4 ohms. Might double check the connections

I assume this is a sealed box, how much insulation does it contain?

[chasw98]

ok details:

Receiver is set to +0, amp gain is as high as it will go before clipping (70-80%). Power output is pretty much correct, as verified by measuring ac output voltage with no load. Subwoofer is wired in phase, and sounds correct in general. Receiver settings are small mains, direct mode, crossover at 60hz. Avalanche is wired in phase, verified to be 4ohm with multimeter (2+2 in series). Amp is bridged mono.

You say you are measuring 90 db at 60 Hz and the receivers crossover is set to 60 Hz. Try setting the receiver crossover to 80 hz for testing if possible, might be some rolloff occurring at the XO point. Why only measure at 60 Hz? Have you measured at other frequencies? If so, what are the numbers for say 30, 40, or 50 Hz? What model receiver are you using to drive the subwoofer amplifier? What model Behringer? Give us specifics and there is a good chance one of us will say "Oh, you using this, and you must do that!", but without model numbers it is hard to say. If you are using a Behringer EP1500 or 2500, have you checked the dip switch settings on the rear of the unit. If not, ignore the on/off labels on the switch and use the guide printed on the back of the amp.

Chuck

EDIT: Thomas is just a little quicker on the trigger than me! :T

[wildfire99]

When I built my twin Ava18"s I had the same issue. Turned out something was mucking up the signal going to the pro amp, and the input level was too low (probably -10db instead of the +4db line level it wanted). The cabling was correct, the receiver output was correct, it was just too much stuff in the chain and one was set wrong. Redoing everything and fixing that made the system insanely loud.

One box was overstuffed, and as ThomasW suggested, that will hurt the output also.

Previous to that, I had a problem with a sub outputting to low that was solved by performing a full receiver reset. It was a Harmon Karmon, so I guess the software glitched as they are wont to do.

[dyazdani]

You say you are measuring 90 db at 60 Hz and the receivers crossover is set to 60 Hz.

That's a good point! I've got mine set at 80Hz and there was quite a null point there (at exactly 80Hz) as verified by measurement with REQW.

[PMazz]

Is that amp rated for 4ohm bridged operation?

That sub should be doing the rumba...

Pete

[Paul W]

If you have low output at 60Hz, with a 60Hz crossover, the sub may be wired out of phase with the mains or in a physical location that puts it out of phase.

Try reversing polarity of the sub and/or moving it so it is no further from the listening position than the mains.

[Fryguy]

I measured with the mains turned off. When roomates leave for the day I might mess around some more I guess.

[Exocer]

Is that amp rated for 4ohm bridged operation?

That sub should be doing the rumba...

Pete

IIRC it is indeed rated at 1400 watts output @ 4ohms bridged.

[Fryguy]

IIRC it is indeed rated at 1400 watts output @ 4ohms bridged.

It is.

[Fryguy]

Ok here is a chart of other spl values.

System setup

Denon receiver, direct mode receiving optical input from a dvd player playing a cd with test tones (alma gates bronco boom cd, if you must know).

Receiver is set to 0db for everything, crossover at 60hz, all other amps are turned off (the subwoofer is the only thing making noise). Gain on the subwoofer amp, which is a behringer ep1500 in bridged mode is at about 75%, the highest it will go before clipping. AC voltage output on a pure tone with no load is about 75 volts, measured with a multimeter by disconnecting the speaker wires from the subwoofer enclosure and connecting them to the multimeter.

The following table lists the values as measured with a radioshack digital spl meter with the commonly known correction chart applied to it (available all over the internet)

Seating position is on the couch, approximately 5 ft away from the subwoofer with the meter extended out (in my hand) into the living room area

20hz: 87.5
25hz: 92
30hz: 96
35hz: 106
40hz: 99.5
45hz: 100
50hz: 98.5
55hz: 94.5
60hz: 95.5
65hz: 91.5

Pretty awful results

[ThomasW]

Again there's something screwed up.

Change the receiver settings. Mains to small and crossover point to 80Hz

Run the measurements again but do them nearfield. (RS meter 1" from dust cap)

I'm thinking you need may something like the ART CleanBox to boost the drive level going into the EP1500. Because that driver with the amount of power your measuring should be blowing you out of the room. Since it's not you may need a higher drive level going to the 1500.

[Dennis H]

How much stuffing is in the box? If it's packed really tight, it could be killing your SPL although it seems like it would still do better than that. Something sure doesn't seem right but it looks like you've done the testing correctly. 75 volts works out about 1400 watts so the driver is getting the voltage it needs but it's not making the SPL.

[Amphiprion]

Just swap the polarity on one coil and see what happens, regardless of what the markings at the terminals are. Also, measure the voltage with the sub connected to the amp. If you're getting 75VRMS at the driver with it connected, then something is wrong with the driver. Swap polarity on one coil, if not that then something is screwed up.

Normally I would expect near zero output with the coils fighting each other, but something is not right.

[Fryguy]

Again there's something screwed up.

Change the receiver settings. Mains to small and crossover point to 80Hz

Run the measurements again but do them nearfield. (RS meter 1" from dust cap)

I'm thinking you need may something like the ART CleanBox to boost the drive level going into the EP1500. Because that driver with the amount of power your measuring should be blowing you out of the room. Since it's not you may need a higher drive level going to the 1500.

I doubt this is the issue, as I can drive the ep1500 well into clipping. So higher input voltage shouldn't do anything except require a lower gain.

I guess I'll try moving the woofer out a little bit from the wall so I can stick the RS meter back there (it's facing the rear wall in the room, about 4" away from the wall).

If anybody in the boston area wants to come and take a listen they are welcome to

Stuffing is liberal. Probably a bit on the heavyside, but not what I would consider extreme or anything.

[ThomasW]

Oops, my brain's toasted on Imitrex (migraine med) so I missed the 75volts.

Only options are way too much damping, VC's miswired, defective driver/VC.

Disconnect the sub from the receiver.

Pull the driver and put it on the floor. Try running one VC at a time, low drive level, do a full frequency sweep from your soundcard into the power amp. Be careful not to burn the VC's.

If all is well with the VC's pull out all the damping and run the levels again nearfield

[Fryguy]

Just swap the polarity on one coil and see what happens, regardless of what the markings at the terminals are. Also, measure the voltage with the sub connected to the amp. If you're getting 75VRMS at the driver with it connected, then something is wrong with the driver. Swap polarity on one coil, if not that then something is screwed up.

Normally I would expect near zero output with the coils fighting each other, but something is not right.

I've done "the battery test" to verify that polarity is correct. (connect battery to speaker terminals, if it pops outward you have correct polarity, if it pops inward the polarity is backwards)

[Fryguy]

Realistically guys, this setup SHOULD be doing around 110-115db at 20hz and possibly peaking as high as 120-123?

[ThomasW]

Realistically guys, this setup SHOULD be doing around 110-115db at 20hz and possibly peaking as high as 120-123?

That's probably a little too optimistic..it should certainly be hitting 110+ in the 40Hz-50Hz range nearfield.

I've done "the battery test" to verify that polarity is correct. (connect battery to speaker terminals, if it pops outward you have correct polarity, if it pops inward the polarity is backwards)

Now's it's pure process of elimination time.

Get the receiver out of the signal path.

Use test tones from the soundcard straight into the EP1500. Watch your mixer level settings and start with the EP1500 input dials turned WAY down.

[jonathanb3478]

But he says he is measuring 75 VAC at the amp outputs at this volume level.

He seems to be getting enough signal to the amp in that case. The issue seems to be that either the sub is not turning enough of the ~1400 watts it is getting into sound, there is a room related issue (he is measuring 60 ft from the sub or some such nonsense), or the actual reactive ohm load the amp sees from the drivers at these frequencies is much higher than expected and is limiting the wattage delivered from the amp.

I do not see how it could be some other kind of issue (receiver output too low, receiver sw glitch, whatever).

Interesting.

[SteveCallas]

Did you make sure you enclosure is actually completely sealed? Also, make sure the dust cap isn't leaking air - some of the earlier Avalanche 18s had a leak between the carbon fiber dust cap and the cone due to the adhesive wearing down.

[chasw98]

But he says he is measuring 75 VAC at the amp outputs at this volume level.

He is measuring 75 VAC with no load. He should hook his voltmeter into the output when he is running the tones he is measuring (I am pretty sure he does not have a 1500 watt load bank). That will give a rough idea of how many watts are being delivered. Thomas is right when he says to eliminate as many elements as possible from the signal chain. If your soundcard will drive the amp to clipping then you have enough voltage driving the amp. Be careful and start out at low volumes lest you end up with a totally non working driver.

[Fryguy]

why is everybody so convinced I have a soundcard lol

I'm using a dvd player as the source for these tests.

[ThomasW]

Then run the one channel DVD analog output directly into the EP1500. Use the amp's input level controls to adjust the sub's output volume (BE CAREFUL) . Start with a high frequency (1Khz) or so and work down.

[joetama]

He is measuring 75 VAC with no load. He should hook his voltmeter into the output when he is running the tones he is measuring (I am pretty sure he does not have a 1500 watt load bank). That will give a rough idea of how many watts are being delivered.

I have seen some EP-1500's only produce about 250 Watts... But they checked fine without a load, have to love some Behringer products. So check it with a load and make sure you are getting the wattage you are needing....

[Mark Seaton]

I've done "the battery test" to verify that polarity is correct. (connect battery to speaker terminals, if it pops outward you have correct polarity, if it pops inward the polarity is backwards)

Polarity is one thing, but IIRC, the coils of the Avalanche 18 are ~2 Ohms nominal each. If you wired them in parallel, I wouldn't be surprised if your amp gave out early. I'm figuring you wired them up in series as intended, but thought it would be worth checking.

Minor leaks would not account for a big loss in output, more so noise during operation.