Lowered the crossover point on my Fathom f113
 

I decided to play with my f113 after reading the information in the thread on setting up Ivan's Stradivari's, and learning that both of Ivan's f113's crossover points in the two channel room were lowered from 80Hz to 35Hz, and consequently delivered a more focused deep bass presentation. My f113 has been optimized to the room, and then fed left and right channel low pass signals from the MEN220 using its active crossover function. This allows me to set up and have complete control over the operating perimeters for the lowpass function that feeds the Fathom. I am using the Linkwitz-Riley 4th order lowpass setting, and had previously set the crossover point to 75Hz. This crossover point seemed to be working well integrating the f113 into the PMC EB1i's, which I am powering with a full range signal.

Yesterday I began playing with the low pass crossover points, adjusting the MEN220 lowpass crossover point down by 5HZ at a time from my original 75Hz starting point while playing several familiar tracks from Brian Bromberg - Choices on the MCD500. I continued lowering the crossover point 5Hz at a time, auditioning with the same music tracks, and repeating the process until I had lowered the crossover point all the way down to a 20Hz. Then I started back up in 5Hz increments, continuing to listen to Brian Bromberg, particularly the track "Never Give Up". What I discovered when I passed the 40HZ crossover point was the bass began to develop a tinge of artificial heaviness that I had not been aware of before. Since I had never tried, or even considered crossing over below 60Hz, I was under the assumption that all was well and good. The PMC EB1i's transmission line bass is so solid and deep on its own that the Fathom really wasn't necessary at all above 40Hz range, and in fact seemed to be adding a small, yet unrealistic weight to the bass when set above that crossover point.

Once I discovered my original 75Hz crossover point was too high, and identified the frequency range around 40HZ as a new crossover point, I continued to make lowpass adjustments from that point, now lowering the crossover point in 1Hz increments down to 20Hz, then back up in 1Hz increments to 40Hz. I listened intently to Brian Bromberg's bass riffs, ultimately settling on 38Hz as the Fathom f113's crossover point. The McIntosh MEN220 is an invaluable tool with its fine adjustment capabilities allowing as small as 1Hz crossover adjustments. The MEN220's active crossover capabilities are a marvel in their own right.

To make sure I was not playing mind games with myself, I spent two more hours listening to a half dozen other CD's from Fourplay, Roomful Of Blues, Chuck Loeb, Liz Story, Patricia Barber and Jeff Beck. I played several tracks at elevated volume above my typical level to ensure that higher volume levels did not produce any audio gremlins I was not hearing at lower volumes. I am now convinced that my old 75Hz crossover point was making bass heavier in the 40Hz to 75Hz range than is natural. At the new crossover point of 38Hz I still have all the solid, well defined bass I like, plus there is a new textural dimension, a clearer definition of bass notes. The sound of vibrating bass strings has more resolution and focus, as does the sound of the initial string attacks.

Lowering the Fathom's crossover point proved to be very beneficial to the complete sonic presentation, and I am pleased to have read Bill (metafacts) and Ivan's comments on their adjustments. Without being encouraged by their changes to Ivan's system, I would have continued to listen at the higher crossover point without realizing there was improvement to be captured with minor adjustment to the crossover point.

Thanks for the great tip, gentlemen.

http://www.soundandvision.com/images...rt/807jl.1.jpg

Great to hear Dan!

I tell ya, this place is "The Gift that Keeps Giving" :)

very good!

I have always thought since listening to studio and live music that many times it is too boomy and not natural. When you listen to an un-amped instrument bass drum, bass upright etc. it is so clean, and most times instead of the nice clean tight deep deep bass there is too much boom. So it makes a lot of sense in your listening room that the lower point would yield a more controlled less in your chest type of bass and more of what you describe.

I know on my sub I roll off at 24 db above 50Hz and 12 per octave from 50 down Dan.

djwhog.......Any adjustments to a subwoofer crossover point are dependent on the room, the speakers in the system, and the ability of the subwoofer(s) to reproduce the frequencies it is assigned. Speaker and subwoofer locations play important rolls in the mix, as well. There are plenty of variables, so each and every sound system will have different parameters. One thing is certain, when you get it right the results are startlingly good.

Personally, I think for two-channel stereo use, an 80Hz crossover point is too high...I don't know where the magical 80 Hz figure came from, but I read anecdotally that it was a figure that was more appropriate in the context of home theatre use. My guess is the reason for this figure is most home theatre setups tend use smaller stand-mount or small monitor-style speakers for FL/FR, SL/SR and center, and 80 Hz is a more appropriate setting for use with these speakers with mid/woofs averaging 4-5" in diameter. The reason a subwoofer is called a subwoofer is that it is designed to augment the lower octaves that a true woofer couldn't handle with appropriate levels of output.

Personally, I'm in the camp that the sub should be crossed just about where the woofs start really start to roll off. In my room, that's about 30 Hz for the left speaker and 45 Hz for the right speaker (the difference in my measured in-room response between L/R is due room and placement differences between the L and R speaker). My REL doesn't have numbers on it as to the XO frequency, but as I have a good measurement system for in-room response, I can measure the XO and gain on the REL to get the best in-room response.

An example is shown here with my right speaker. The brown trace is my Contour S3.4 w/o the REL, which you can see rolls off around 45 Hz. The purple trace shows the effect of adding in the REL, and how it fleshes out the lower octaves and balances the in-room response of the right speaker.

http://photos.imageevent.com/puma_ca...%20comparo.jpg

This trace is my left Contour, you can see that it rolls off at about 30 Hz, and the green trace shows the sub again providing some added LF fill.

http://photos.imageevent.com/puma_ca...20no%20sub.jpg

The differences between the L and R Contour with respect to rolloff is not a speaker difference, but a reflection (no pun intended) of each respective speaker's position in the room.

Agree 100% I play so much with passive and active crossovers, on the systems That I build. I setup a test crossovers that are external so that I can mod them at will even after determining the ballpark Hz points slopes etc per design, but the final is always in the room and the ear. Once I achieve the result I want I put the high-end parts in place and lock down the passive part of the unit.

But is as you say, so much on placement and room etc.

Let me ask something, do we have a thread on acoustic panels, purchasing and placement? I would like to start doing some additional updates to my listening room. i think it is a HUGE are over looked that can add a lot of improvement.

thanks budyy:)

Dan: Absolutely correct; couldn't have put it better myself. :thumbsup:

See my post above for a graphical example.

Additionally, it's not only the sub and speaker locations, but your listening position with respect to the speakers as well. I can measure different in-room frequency responses with as small as a six inch differences in listening position. Also, the in-room frequency response will change with you sitting in your chair compared to the measurement mic just at the listening position on it's mic stand.

What I've learned from extensive playing around with all this is just what Dan has pointed out....the speakers, sub, position, room, and your listening position are all part of a SYSTEM and they all interact with one another. Small changes can make notable differences in the performance of the system.

Have to agree with the lower crossover point also.

I have my f112 crossed over at 30hz - 24db slope. Its perfect.

Do the fathom's get even better after some running in? :D
These subs are amazing :yes:

Often I have wondered what it would be like to have automated, room correction features on my sub or pre-amp. I had a REL Stentour which has manual adjustments. Looking back I bet it took me a year to perfect my setup with the REL and Electa-Amaters. During this journey I learned a lot about setup. I think 80hz is way too high for 2 channel high performance systems. Richard E Lord advertised his subs as sub-bass not sub woofers. The idea being to feel not hear muddy bass and that proper set-up would enhance soundstage and detail.

My crossover point was set between 32 and 38hz depending on the material

Yes, we have an ASC Tube Trap Forum also.