Dennis Had Inspire Amps

[Rosco65]

Originally Posted by nhparrot

After trying 50Hz and 70Hz High Pass Harrison FMOD's in my system I have removed them from the signal chain. Testing with a SPL meter and the Rives Audio Test CD, I found that the FMOD's lowered the input signal to my amp at frequencies above the FMOD crossover point.

The FMOD's are passive devices - they work by attenuating signals only. According to Harrison Labs they are 12dB/octave, though I have heard reports in practice they are closer to 6dB/octave.

In either case, these slopes are relatively shallow (i.e., they are not brick wall filters at 50hz or 70hz) and will offer a fair amount of attenuation above the knee frequency. Additionally, the actual corner frequency may differ from the nominal corner frequency depending on your amp's input impedance.

One "solution" is to remove them from the signal chain and your amp will again receive a full-bandwidth signal. Another option is to choose a different nominal frequency (e.g., 20 hz or 30 hz) to correct for your system differences. I think with devices like these, it is important to either measure or experiment with a number of frequencies. In the case of FMOD's, at $27.50 per pair I think we can easily swap them out.

[pstrisik]

Originally Posted by nhparrot

After trying 50Hz and 70Hz High Pass Harrison FMOD's in my system I have removed them from the signal chain. Testing with a SPL meter and the Rives Audio Test CD, I found that the FMOD's lowered the input signal to my amp at frequencies above the FMOD crossover point.

Any electronics without gain will do that. I did a similar test a while back and found 2-3db insertion loss, IIRC. I think the benefits may outweigh that loss however. A higher quality high pass filter might do better, but the Harrison's give a great opportunity to experiment at very modest cost.

[Musica Amantem]

Originally Posted by nhparrot

After trying 50Hz and 70Hz High Pass Harrison FMOD's in my system I have removed them from the signal chain. Testing with a SPL meter and the Rives Audio Test CD, I found that the FMOD's lowered the input signal to my amp at frequencies above the FMOD crossover point.

Even if not too accurate, I personally noticed a significant improvement with these filters. In fact, because I don't have reinforcing (overlapping) bass anymore (in general terms), the SUB's shortcomings have been put in evidence, which is another sign these filters have improved the overall presentation.

[x3workshop]

Originally Posted by nhparrot

After trying 50Hz and 70Hz High Pass Harrison FMOD's in my system I have removed them from the signal chain. Testing with a SPL meter and the Rives Audio Test CD, I found that the FMOD's lowered the input signal to my amp at frequencies above the FMOD crossover point.

I think the 12db/octave slope works pretty well in my setup. I've not noticed any audible signal degradation. In fact, using these with my Inspire setup has improved the listening experience for me.

It may be a completely different experience in yours.

[Musica Amantem]

BTW, I've come to the conclusion that Rythmik is the way to go with my SUB upgrade. I considered PSA, SVS (SB 2000) and Rythmik L12 / F12G, and it came down to this:

1. stereo setup with Rythmik L12's
2. Single Rythmik F12G

Which option do you guys believe would be my best bet, as I cannot afford a stereo setup with the F12G, in itself a very valid alternative. Posing this question here for the familiarity with the amplification part of the system. I also posed the question to Rythmik, as given the budget constraints they should provide a candid reply. I remind you my setup is near-field in a small room.

Thanks for any inputs.

[pstrisik]

Originally Posted by Musica Amantem

BTW, I've come to the conclusion that Rythmik is the way to go with my SUB upgrade. I considered PSA, SVS (SB 2000) and Rythmik L12 / F12G, and it came down to this:

1. stereo setup with Rythmik L12's
2. Single Rythmik F12G

Which option do you guys believe would be my best bet, as I cannot afford a stereo setup with the F12G, in itself a very valid alternative. Posing this question here for the familiarity with the amplification part of the system. I also posed the question to Rythmik, as given the budget constraints they should provide a candid reply. I remind you my setup is near-field in a small room.

Thanks for any inputs.

If you are not looking at a second F12 down the line, in your shoes I would definitely go with the pair of L12s unless there is something in the amp configuration of the F12 that you need. Everything I'm reading indicates the L12 is not at all far from the F12 in pure sound quality and output. My bet is that two of them vs. one F12G would perform better in a system in a room. Two subs really helps even out peaks and dips around the room and wouldn't have to be pushed as hard as a single sub.

[Musica Amantem]

Originally Posted by pstrisik

If you are not looking at a second F12 down the line, in your shoes I would definitely go with the pair of L12s unless there is something in the amp configuration of the F12 that you need. Everything I'm reading indicates the L12 is not at all far from the F12 in pure sound quality and output. My bet is that two of them vs. one F12G would perform better in a system in a room. Two subs really helps even out peaks and dips around the room and wouldn't have to be pushed as hard as a single sub.

The only differences are about 70 watts more power for the amp with a single driver and the quality of the driver cone of the F12G , which is a design from GR Research, extending the bass further up to allow for a higher cross-over setting, of up to 120 dB. The F12G also has a lower cross-over range (low pass) of 25 Hz vs 30 Hz for the L12.

Since my room is small, two 300-watt drivers (stereo) should be better, power wise, than the single 370 watts of the F12G. In addition, since I cross-over at 100 Hz (because of my fixed High Pass filters), the F12G's extended bass capability won't be used much at that 100 Hz cross-over as opposed to someone crossing at 120 Hz. But, this is only my assessment, so I'm open to corrections.

Thanks for your thoughts.

[Musica Amantem]

Just received word from Rythmik:

"I would go with a pair of L12s. I have a L22 in my nearfield desktop setup paired with Dynaudio BM5 mkIII monitors and it sounds amazing."

So, apparently a pair of L12's beat one 12FG for about the same investment.

[pstrisik]

Originally Posted by Musica Amantem

Just received word from Rythmik:

"I would go with a pair of L12s. I have a L22 in my nearfield desktop setup paired with Dynaudio BM5 mkIII monitors and it sounds amazing."

So, apparently a pair of L12's beat one 12FG for about the same investment.

That's probably Enrico, the right hand man.

Now that you've apparently decided, keep in mind that Rythmik is near Austin Texas. Not quite Houston, but everything around there might be slowed down with the storm.

[Rosco65]

Originally Posted by pstrisik

If you are not looking at a second F12 down the line, in your shoes I would definitely go with the pair of L12s unless there is something in the amp configuration of the F12 that you need. Everything I'm reading indicates the L12 is not at all far from the F12 in pure sound quality and output. My bet is that two of them vs. one F12G would perform better in a system in a room. Two subs really helps even out peaks and dips around the room and wouldn't have to be pushed as hard as a single sub.

My direct experience with Rythmik subs is limited to the F8's I own, but I do own a couple other subs and a number of GR Research speakers. I can offer these opinions:

1. The biggest difference between the L12 and the F12G is the amplifier. The L12 uses a Hypex HX300 amp which only accepts line inputs (stereo and LFE). It is similar to the amp in my F8's. The F8 has a similar amp with two 300 watt modules, one for each driver. The F12 uses the larger, class AB amp with about 400 watts. This amp allows for much greater control (PEQ, etc.) and allows speaker-level connection. I have no opinion regarding which amp is superior.

2. In another forum, Jim Salk as stated that the rated output at 20hz is identical for the L12 and F12G. The F12G may go a bit deeper, but in my world I have little need for output below 20hz. The F12G driver is a really nice driver, custom designed by Danny Richie with a cast frame. The L12 uses an off-the-shelf paper driver with a stamped frame (though Jim asserts that the face plate on this driver is particularly thick).

3. The L12 is also in a smaller enclosure designed to fit in the USPS shipping parameters. This helps Jim market this for $539 shipped in Conus.

If I had $1,000 to spend on Rythmik subwoofers I would choose two L12's over a single F12G or F8. If I were ultimately looking at spending $2,000 I would purchase two F12G's in your case. However, one could make the argument that you money would be better spent on four L12's, but now we are getting silly.

Another alternative - applicable since you are located outside of free or cheap shipping zones - is to purchase the custom installation option (drivers and amps only) and have the cabinets built locally. The cabinets are really just well-braced sealed boxes that almost anyone could make.

EDIT: I wrote this before the other replies. It is comforting to get some confirmation direct from the source.