warriorant85 wrote: Hey guys,

...... I ended up trying some bass warble tones I got with my HSU subwoofer and noticed that there was a significant drop around 50Hz. The next tone sample was at 40Hz and the output at my listening position was back to the levels I saw at 60Hz and above. Same for 31.5Hz. However, by 25Hz, the output levels were way down and there was essentially no output at 20Hz..... Any recommendations short of moving?

Hi Mark. As you're asked for recommendations I might suggest scrutinizing the source of the warble tones and the measurement device itself. Sometimes bass frequencies at 25Hz and below can be difficult to accurately reproduce. Perhaps try other kinds of test tones in that bass region other than warble tones. Moreover, this low frequency range borders the infrasonic region and in this region human hearing becomes gradually less sensitive as frequency decreases. To perceive infrasound the sound pressure must be sufficiently high. I've successfully reproduced 20Hz with my T1's and they are rated by GET to go even lower so I'm fairly sure you too can achieve it

HI Pbgalvin,

I have been interested in Sandy's home theater systems since his Definitive Technology days. However, it's only been in the last couple of years that my wife and I have been actually assembling a system based on his products. The T1s are the final big piece of the home theater and they are also used as the speakers in a 2 channel audio only setup. The T1s are being fed full range audio from an eight channel preamp to a pair of monoblocks, in addition to a seven channel amp for the rest of the speakers. With this arrangement, I can route 7.1 audio from the bluray player or the prepro to all amps, in addition to 2 channel only. The sub is normally only active with 5.1 or 7.1 source media, so the bass dropouts were noticed only with full range 2 channel audio to the speaker connections on the T1s. By the way, I am splitting the LFE to the sub and both T1s for home theater and it sounds great! The testing I had been doing was very basic and only gave me the idea that I needed to investigate further. Come to think of it, the potent bass I used to hear in my 2 channel setup, on some music, may just as well have been related more to antimodes that gave me too much bass, rather than any deficiencies with my current setup. After more extensive listening and some more measurements, it looks like I have plenty of bass from about 27Hz through 40Hz, with a dropout between 45 and 55Hz. Most of my music sounds as good or better than what I've been accustomed to, so I'm very happy with the setup. I just wish I had more leeway for moving the T1s around in the room. If this was a dedicated 2 channel system, I would have a lot more free space to try different locations. Oh well, c'est la vie!

Thx,

Mark

Hey Mark,
The usual "make the best sound in the place not dedicated for sound" problem. I have the same one.
If you do track this down to standing wave nodes, you might look into something like "bass traps" (I think they are called), corner treatments etc. But I recall they don't look that great...

The other usual solution (aside from moving is to pollute your pure audio stream via equalizer settings if your preamp / receiver has those - bump up the 45-55 hz range.

Hi GDHAL,

I am only using an old RadioShack SPL meter to make sound checks, so certainly not sophisticated! I am planning to pickup a MiniDSP 2x4 HD with a UMIK-1 mic to get some more verifiable readings and possible correction, but no rush. This weekend, I used a different source for a tone generator with a sweep from 20Hz to 300 HZ. Wow, lots of dips and peaks! What fun! I did notice I have plenty of output below 30Hz, so great for home theater and certain music. The drop I was referring to seems to be between 45 and 55Hz, but there's several other drops even more pronounced at higher frequencies. I think I'll just enjoy things the way they are for now, with an eye towards more extensive troubleshooting, down the road. Thanks for your input!

Mark

Hi Pbgalvin,

That's exactly the issue! I may consider bass traps to deal with the nodes & antinodes, but we are limited on space, even for acoustic treatments, especially down low in the corners. Regarding your other suggestion, I actually do have a nearly brand new stereo pro equalizer I could add in, but I think I would probably only use it with a passive A/B audio switch, so I could just add it in for the right occasions!

Mark

Another thought I was wondering about was that, if these deep dropouts are created by nodes (cancellations), wouldn't increasing acoustic energy at those frequencies also increase the cancelling energy and create a no win situation, unless using bass traps?