Help! HSU STF-3 barely audible

[The Jay]

I saw it on Kijiji. I went to the seller's home and he turned on some music on relatively low volume and I heard the STF-3 working just fine. He turned up the music to around middle volume and the sub's power and volume were quite evident. I felt underneath and the driver was moving normally.

I can't see any aspect of its handling that would have jarred anything loose... he disconnected it, and loaded it into my car's rear seat, with the front side down on the seat and the amp side up. I transferred it into my house carefully, it wasn't dropped or anything.

I've hooked it up to a Denon AVR E-400, which has a single subwoofer output. The sub has dual inputs for the Low Level Input. As per instructions, I've hooked up the sub cable to the white, left Low Level Input. Phase is set to 0. Crossover is switched to 'out', to allow the receiver to do the job. The power light is green when the switch is 'on' or in the 'auto' position. So I assume it's getting a signal ok. The volume dial is set to 2:00.

But the volume is incredibly low. Like, barely noticeable.

I've tried everything I could think of, even stuff that shouldn't make a difference. I've played with every control on the sub itself, I've tried a Y cable to have both inputs on the Low Level of the sub getting a signal, I've cranked the volume dial on the unit itself. I have used a different sub cable to see if that was it.

Still the volume is very low. I know it's getting something...I can feel the driver moving but barely.

On the Denon, I had to crank the subwoofer level to 10.5/12 just to get this barely audible volume (with sub's volume knob to 2:00 and above). I tried running audessy. When it starts to send a pulse tone to the subwoofer it does so 3 times. The first is barely audible with me next to it. The second is louder but still sooo quiet. The third is louder still but still way too quiet and then Audessy reports that the volume is too low to continue.

The Denon's LFE is set to 120hz.

Does anyone have any ideas on what I can try next? I can unscrew the amp on the sub to check for an anomaly but I wouldn't know what to look for. Help please!

 

[William Lemmerhirt]

Lfe is at 120. What is the XO at in the avr?

 

[lovinthehd]

Scratching my head, was wondering about Xover myself but assume you've experimented with that. Do you have another unit you can use to test the sub to rule out the avr being faulty? Even a portable device might do the trick....

 

[j_garcia]

Try another cable too. Do you have the x-over set on the sub? That should be set to its highest point.

 

[shadyJ]

I would unscrew the driver and make sure the leads are connecting from the amp to the driver. I would also try another source to make sure it is the sub and not the receiver's LFE output. The bad news is if something got messed up on the amplifier, it won't be cheap to replace.

 

[The Jay]

Thanks to everyone for the input.

Crossover in the AVR is at 120 for front, centre and surrounds, as per Goldenear's specs for the sat3's. Crossover is off on the sub itself, though I've tried every dial just to be sure. I'm about to lug the thing downstairs to try on my other setup. If that fails, I'll try unscrewing the driver as suggested. I'll post pics if I get that far.

HSU tech support got back to me quickly and said that if another source yeilds same result I need a new amplifier [as noted, the bad news :-( ], which would mean ordering the "VTF-3 MK4 amplifier. That would run $235 plus $25 S/H if you are in the lower 48 states".

I'm not in the lower 48...I'm in Canada...and our dollar sux.

 

[everettT]

Just to confirm, your speakers are all set to small?

 

[ParadigmDawg]

Just to confirm, your speakers are all set to small?

That's what I am thinking too.

 

[The Jay]

well I don't have that kind of plug. My other sub works just fine on the subwoofer out coming from the Denon.

But I took it downstairs to try it with my Marantz unit. . . same result. I have two Triton 2+'s hooked up to that unit using the 'subwoofer out' with no problems, fully adjustable.

But nothing comes out of this unit, or it's barely audible no matter what I do with settings or controls on the unit itself.

I emailed HSU for their opinion. They think it needs a new amp. They say 250USD shipped to lower 48, but I'm north of the border...and paid just over 200 CND for it. . . so if I can't repair the unit, I don't know if it would be worth putting that money into that unit.

I can't for the life of me figure out what could have gone wrong, what it could possibly be, or how to fix it.

I guess I've got to crack open this thing and look for any anomalies. Any ideas on what I should look for, as I do this? Really any help is appreciated.

 

[shadyJ]

Jay, you don't absolutely need Hsu's plate amp. The truth is a lot of amps will work with that sub. You will want to use something that puts out 250 to 400 watts at 4 ohms. You will also want to put a high-pass filter on the sub at around 20 Hz- I think these would work well enough for that.

You could pull out the plate amp and look for some problem, but it might not be obvious to a layman. Maybe something became loose during transport that you can see.