STF-1 or STF-2?

[TheNit]

I want to set up a 10'x14'x8' (1120 cu ft) room with terracotta tile flooring for stereo listening only. I have older Paradigm 7se's that have 8" woofers, 1" tweeters for the room. I'm looking at the idea of getting a sub to enhance the sound. I'm looking at the STF-1 or STF-2. Which would make more sense? The website says that the STF-1 would be good up to 1500 cu ft but I was wondering if it would be strong enough, given the range of the Paradigms.

I would be using the speaker in/out's to connect the sub with the Paradigms.

Specs for Paradigm 7se
Frequency range 31.5Hz - 24kHz
Frequency response 60Hz - 20kHz +/- 2dB at 0
60Hz - 15kHz +/- 2dB at 20
Sensitivity: Room/Anechoic 91/88dB
Dynamic Power Range 15 - 100 watts at 10% clipping
8 ohms Impedance

Any opinions? Would the subs make much of a difference?

[RossK]

I would go for the STF-2 for the lower extension it provides. You'll appreciate that for home theater use. For music, then either is great. I have an STF-1 that I'm using for just that purpose.

[TheNit]

It is strictly for music but I wonder if the STF-1 will be heard alongside the Paradigm's. Is it worth spending the money?

[RossK]

Originally Posted by TheNit

It is strictly for music but I wonder if the STF-1 will be heard alongside the Paradigm's. Is it worth spending the money?

It should be able to very easily hold its own. I'm using it with some Ascend Acoustic Sierra-1s and a UPA-2 amp (125 wpc) and it does fine. It really just comes down to the power of your amp and level-matching the sub to the mains.

FYI. I'm not sure if you're using a receiver, or separates, with sub-outs, but the STF-1 only has a low pass filter. This is true with most subs though. If you are using the speaker inputs, instead of low-level inputs, then you'll have to cross it lower to keep from having bass bloat.

[TheNit]

I'm using the 2nd zone of a Marantz 110 wpc receiver (SR6004) so I basically only have the high level speaker option. I would be connecting the receiver's zone 2 spkr outs to the STF-1's spkr in and the STF-1's spkr out to the Paradigms. The Paradigms are good down to 60Hz at +/-2dB so I'm guessing that I would set the crossover to 60Hz as a starting point.

[RossK]

That sounds reasonable Nit. You might start at around 80Hz though and see how it sounds, then go down from there. Pete may chime in during work hours tomorrow to possibly offer more advice.

Good Luck!

[TheNit]

Peter,

Could you give your opinion on this? I now understand that the low-pass filter means that the full signal would still be going to my mains. If my mains can go down to 31.5, the same as the STF-1, what's the point? Maybe I'll have to get a sound meter sna see how low the Paradigms will actually go.

Thanks

[kinggimp]

Originally Posted by TheNit

Peter,

Could you give your opinion on this? I now understand that the low-pass filter means that the full signal would still be going to my mains. If my mains can go down to 31.5, the same as the STF-1, what's the point? Maybe I'll have to get a sound meter sna see how low the Paradigms will actually go.

Thanks

nit,

The low pass filter makes sure frequencies higher than a certain point are not passed to the sub. So if you set the crossover on the sub to say 80 it should send frequencies from 80 and below to the sub and everything above that to your main speakers. The sub would handle the frequencies between 31.5 through 80 and your mains would handle everything up both 80.

[Bill Mitchell]

Andrew, I think Ross was correct that the STF subs, like the VTF subs, have a low pass filter only, not a crossover. See the Crossover Type entry on the last page of the manual. So if one is using the high level connections, the mains will get the full range.

[kinggimp]

Originally Posted by Bill Mitchell

Andrew, I think Ross was correct that the STF subs, like the VTF subs, have a low pass filter only, not a crossover. See the Crossover Type entry on the last page of the manual. So if one is using the high level connections, the mains will get the full range.

When using the high level speaker connections you are using the subs internal crossover instead of letting the receiver do it. You just have to have the crossover switch set to in instead of out. That way you can control what frequency at which the sub takes over. This way the speakers are not running full range. On page 5 of the manual it explains it.

[kinggimp]

Originally Posted by Bill Mitchell

Andrew, I think Ross was correct that the STF subs, like the VTF subs, have a low pass filter only, not a crossover. See the Crossover Type entry on the last page of the manual. So if one is using the high level connections, the mains will get the full range.

I guess you're right after I looked at it further. But if his mains are rated down to 60 he can increase his extension from 60 down to 31.5 and just set the crossover at around 60. They would still be full range but since the only go down to 60 it shouldn't matter.

[Pete_Hsu]

Both the STF-1 and STF-2 will make for a very nice addition to this system. TheNit shared some SPL measurements for the mains, and the response actually starts rolling off a little bit below 80Hz.

Feeding the high level inputs on the STF subs, and then using the speaker outputs back to the main speakers will not filter out lower frequencies going to the main speakers unfortunately. It is my understanding that the VTF amps have some circuitry which tries to block some lower frequencies going to the mains when using the outputs back to the speakers, but I'm not sure how effective it is, and definitely not anything like a true high pass filter.

All the modern day receivers have built-in bass management with high and low pass filters for speakers and subwoofers respectively. For two channel systems, one can use our high pass filter (although for one to use it with a single STF sub would require use of a custom cable that sums left/right channels to mono).

Sincerely,