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Two identical subwoofers, very different output = defect? (1 Viewer)

kalm_traveler

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Hey guys I hit up the manufacturer too but figured I would ask here as well to try to figure this out.

I've had one HSU VTF-15h Mk2 since 2014 and love it, absolute beast. I just got another one last week and it seems to be much weaker than the original unit.

My room is about 12' wide x 24' long x 8' tall and I'm using about half of it for the HT viewing area.

AVR is a Yamaha RX-A3080, have two different subwoofer RCA cables.

Doing the sub crawl to find the 2 best spots in the room for placement (where the bass response is the flattest) with an SPL meter I found that basically the front left and rear right of the HT area respond the best so I have the subs in those 2 spots.

per HSU setup recommendation I have left the old sub with volume about 9 o'clock, EQ1 setting, Q 0.7, 0 degrees, 1 port open and YPAO usually sets its level to -7.0 or so, I usually raise it to -6.0 or -6.5 for preference. I set the new one the same.

With identical settings, I could tell that the new sub was not giving anywhere near similar output. I first tried swapping them (so swapping locations, cables and AVR outputs) and no surprise where the new one was, there was very low output. Running YPAO again after checking that both had identical settings (9 o'clock volume), it set the old sub to -10 dB and the new one to +7.0 dB.

A quick and dirty test to try to get the bass response in the seating area to seem even, I had to increase the volume knob on the new sub to about 1 o'clock.

Does this not seem like there's something wrong with the new sub?
 

JohnRice

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You need to volume match the two subs. 9 O'Clock volume on a 7 year old sub isn't necessarily going to be the same as a new one.

I think you have an SPL meter. So, turn off the new sub and play a test tone on the old sub. Adjust the volume on the receiver so it plays back at a usable level, like 75dB. Then turn off the old sub and turn the new one on. Play the same test tone and adjust the volume on the sub itself (NOT on the receiver) until it's also 75dB. Now they're volume matched.

The subs need to be in their final position when you do this. If you move either of them, they need to be re-balanced.

EDIT: I should have said, set the trim levels in the receiver for both subs to 0 first. then you can run YPAO if you want, to let it do fine tuning. This process will just make the output trims of both subs be about the same.
 

kalm_traveler

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You need to volume match the two subs. 9 O'Clock volume on a 7 year old sub isn't necessarily going to be the same as a new one.

I think you have an SPL meter. So, turn off the new sub and play a test tone on the old sub. Adjust the volume on the receiver so it plays back at a usable level, like 75dB. Then turn off the old sub and turn the new one on. Play the same test tone and adjust the volume on the sub itself (NOT on the receiver) until it's also 75dB. Now they're volume matched.

The subs need to be in their final position when you do this. If you move either of them, they need to be re-balanced.
Thank you John - I will try that.

Still, seems a bit odd that the older sub would require far less 'volume knob' than the new one doesn't it? I never really adjusted the old one since 'about 9 o'clock' was plenty loud. For the new one to sound ear-wise roughly comparable it needs to be about 1 o'clock.

If I'd ever set the old one to 1 o'clock my house would have fallen apart.

Anyway I'll volume match them with the SPL meter or that mic you had me buy (arrived a few days ago). I'm just concerned that there may be something wrong with this new subwoofer.
 

JohnRice

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I added a bit to my first post regarding resetting the output levels on your receiver. You want to be sure the outputs for both subs are equal before matching them.
 

JohnRice

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BTW, you don't have to do this since YPAO should balance them. It just kind of evens things out, and 17dB is a pretty big discrepancy between the levels of the two subs. Level balancing them at the sub volume will just make the final calibration simpler.
 

kalm_traveler

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BTW, you don't have to do this since YPAO should balance them. It just kind of evens things out, and 17dB is a pretty big discrepancy between the levels of the two subs. Level balancing them at the sub volume will just make the final calibration simpler.
Aye, as far as I know YPAO maxes out at -10 dB so as I mentioned I'm a bit concerned with the new sub being so much quieter.

Doesn't seem that the old one should be exponentially louder in the same spot with the same volume knob level.
 

JohnRice

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Aye, as far as I know YPAO maxes out at -10 dB so as I mentioned I'm a bit concerned with the new sub being so much quieter.

Doesn't seem that the old one should be exponentially louder in the same spot with the same volume knob level.
Volume matching will solve the first problem. Sub calibration is more complex, since there are two volume controls.

I really wouldn't sweat the difference in volume settings of the two subs. If you bought them at the same time I'd be concerned, but since they are seven years apart, I wouldn't be concerned. The amp is no doubt a little different across all that time.
 

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