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Phono stange with Subsonic Filter

Olecranon

Olecranon

Active Member
I just picked up a second subwoofer for my system, and now I have the dreaded woofer pumping issue when playing Vinyl. My current Phono preamp is a Rega fono mini so my current line of thinking is to get an upgraded phono preamp that has a subsonic filter.

So far I've been able to come up with three options.

1) Cambridge Audio Azur 651P - Has a built in subsonic filter, but I have no idea what frequency it starts to filter. I also don't know how steep the filter slope is. I can't seem to find this info anywhere.

2) Pro-Ject Phono Box DS - Has a built in subsonic filter. It starts at 20Hz and attenuates 12db/octave. I was looking at some of Pro-Jects older products such as the Phono Box II SE and they were 18Hz with a 24dB/Octave attenuation. I wonder why the new ones are different?

3) KAB RF1 - Strictly a subsonic filter. 20Hz with a 18dB/Octave attenuation. If this thing was $50 it would be a no brainer. At $180 I would much rather spend the money on a better phono preamp.

Any suggestions? Looking to spend $500.

additional info : My turntable is a modified Rega RP1 w/Ortofon 2M Blue cartridge. My turntable is isolated with two sets (8) of Herbies tenderfoots. I have 4 tenderfoots under a bamboo cutting board, and then 4 more tenderfoots under the turntable.

Thanks!
 
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Subsonic woofer flapping is usually caused by subsonic arm/cartridge resonance and has little or nothing to do with vibrating air. The same thing would happen in a vacuum.
 
The Pro-Ject units are very well made and nice sounding. If you can find an older one for a decent price, jump on it. I can tell you the sub filter works very well in those units. I had both the Tube Box II and SE.

jblnut
 
Yes, sonic/subsonic excitations travel through gas, liquids and solids znd cause thrm to become excited.
Second subwoofer seems the cause, ditch it.

I'm not much of a "sub" fan either.
 
Those FMODs have a 12dB/octave roll-off - a bit too gentle to an effective subsonic filter.
Also, there doesn't have to be any feedback - either through air or anything else - to excite arm/cartridge resonance. Simply putting the stylus onto the record or any little warp will set off the resonance.
It's not clear from the OP's post if the subwoofer is making the problem worse or just making it easier to see.
 
A subsonic filter, a high-pass filter is in reality not the cure of the problem. The arm arm/cartridge will still continue to vibrate and still cause freq mudulations of all music signals. It´s much better to look into the real problems, this will get you a better sound and no need for any high-pass filter. Look into air-born vibrations, structural born vibrations and arm/cantilever damping problems.
 
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Did you have any if these issue with the first sub? There's no mention of this in the first post. How do you have both subs connected?
 
I think the final solution is going to need to be a combination of isolation and subsonic filtering.

When I first got my TT, I had audible issues. My room has laminate flooring, and I was setting the Rega on a buffet which is where I store my albums). I purchased a set of four Herbie's Tenderfeet, and used them in conjunction with a bamboo cutting board as a phono stand. That really eliminated any audible rumble that I was having. The first sub (Vandersteen V2W) never appeared to have issues, but that sub is decoupled (if that even matters) from the floor with spikes resting on brass disc. Also, it's VERY difficult to see the drivers with the Vandersteen sub. The entire thing is wrapped in very dark cloth.

The new Martin Logan Grotto i did not come with any floor spikes. The entire bottom surface is resting directly on the floor. The woofer is also VERY easy to see.

I did an experiment where I turned the platter off and just rested the needed on an album. I turned the volume up, and I could see the woofer flutter. This shouldn't be a compliance issue with my Tonearm/Cartridge combo?

I also added one of those 20Hz -12dB/Octave in-line RCA filters at the subwoofer. It did make some difference, but didn't come close to eliminating the issue.

Frustrating.
 
Olecranon said:
I think the final solution is going to need to be a combination of isolation and subsonic filtering.

When I first got my TT, I had audible issues. My room has laminate flooring, and I was setting the Rega on a buffet which is where I store my albums). I purchased a set of four Herbie's Tenderfeet, and used them in conjunction with a bamboo cutting board as a phono stand. That really eliminated any audible rumble that I was having. The first sub (Vandersteen V2W) never appeared to have issues, but that sub is decoupled (if that even matters) from the floor with spikes resting on brass disc. Also, it's VERY difficult to see the drivers with the Vandersteen sub. The entire thing is wrapped in very dark cloth.

The new Martin Logan Grotto i did not come with any floor spikes. The entire bottom surface is resting directly on the floor. The woofer is also VERY easy to see.

I did an experiment where I turned the platter off and just rested the needed on an album. I turned the volume up, and I could see the woofer flutter. This shouldn't be a compliance issue with my Tonearm/Cartridge combo?

I also added one of those 20Hz -12dB/Octave in-line RCA filters at the subwoofer. It did make some difference, but didn't come close to eliminating the issue.

Frustrating.
Click to expand...

It´s a damping issue that is the main problem, the arm resonates and that is the woofer pumping. It´s very common.
 
Hmmm, probably try matching the arm & cart (weight & compliance)?
Grounding?
Check the headshell wires?
 
gusten said:
It´s a damping issue that is the main problem, the arm resonates and that is the woofer pumping. It´s very common.
Click to expand...

I think your correct in my circumstance. I just installed a turntable wall mount. The woofer pumping is greatly reduced, but still present. I can listen to my table now at lower levels, but the woofer starts pumping once I start turning up the volume. The movement isn't as much, but eventually the pumping becomes audible.

At this stage I feel like I have two options.

1) Try a KAB RF1 filter.

2) Go another direction and buy a better turntable.

Is it worth trying to wrap the tonearm with Teflon tape?
 
I have a Systemdek that suffers the woofer pump..no matter the cart..come to think of it may be a location thing as the table previous did the same, either one sat next to a LP12 that has no pump. For the hell of it I tried an old pro-ject tube phono box with an 18hz filter..that fixed it, and sounds pleasing to boot(with some decent tubes).
This thread got me thinking location..being in the corner-ish may be an issue but I can say the tube box band aided it nicely.
 
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