Auto-On Switch Question

[Audiosaur]

I tried unsuccessfully to search the forums for an answer so...curiosity question about the auto-on switch on my Hsu VTF2-MK5s, driven by a Pioneer SC-LX501:

Both subs are set auto-on, manual volume settings on each at 9 o'clock position. Listening to music, average 60db at the LP, Hsu #1 will turn on without issue but, invariably, #2 doesn't turn on until I add more juice (at about 65db). I thought it was just a Y-splitter in the Pioneer, meaning the same signal should be going to both. Why aren't they both responding identically?

Nothing wrong with the subs' performance; when they're on, they're fabulous.

 

[shadyJ]

I would guess the gain dial on the sub is not the same. Hsu did say they were going to switch from a logarithmic scale on the gain from the first VTF2.5s to something less aggressive on later units. '9 o'clock' is just an arbitrary position on the gain dial and it does not mean they are level matched. One thing you can do to double the input voltage is use a Y-splitter to go into both inputs on the VTF-2. That will make it turn on easier, but you will want to turn the gain dial down if they are level matched currently.

 

[Pogre]

I would guess the gain dial on the sub is not the same. Hsu did say they were going to switch from a logarithmic scale on the gain from the first VTF2.5s to something less aggressive on later units. '9 o'clock' is just an arbitrary position on the gain dial and it does not mean they are level matched. One thing you can do to double the input voltage is use a Y-splitter to go into both inputs on the VTF-2. That will make it turn on easier, but you will want to turn the gain dial down if they are level matched currently.

Exactly my thoughts. The gain dials are usually not set the same, as per Hsu. Mine werent. When I spoke with Kevin (HsuKevin) about it he said that gain matching is always a good idea.

Audiosaur, gimme a second and I'll edit in the link from my post when I did it. It's pretty easy.

 

[Pogre]

I forgot! Here it is.

 

[Audiosaur]

I forgot! Here it is.

Thanks Pogre. I also did some web searching for the best way. Because I didn't want to lug the subs around, I decided to level match, trying to get the same spl from each at the LP. I'm not worried about overworking one to get a desired response - I never listen that loud.

So I did a little test and here are the results:

I ran it twice with both subs. Sub 1 is in the back right corner, sub 2 is front wall, left of center. I played seven different freqs from the Hsu test disk and monitored the spl readings on my phone to approximate an average over the 20 second tone. Not precise, I know, which is why I did it twice.

Anyway, what I found most interesting was that while the corner sub had better response down low, #2 held it's own at mid-bass. Unless I find a better location for #2, this is about as level matched as I think I can get.

 

[Pogre]

Sounds like level matching is a good way to go with your subs in opposite corners like that. One in front and one behind. Mine are both right up front, one by each speaker. The difference in the positions of the gain knobs on both of mine were pretty significant. They were off by a full half notch. They sound a lot better now that they're gain matched.