You are experiencing acoustic feedback. There are two types, structure borne, which enters through the rack, or stand, and is transmitted through the TT suspension, and airborne, in which sound waves directly excite the plinth of the turntable.
Since you have already made a very smart move and gone to the wall shelf it might be best to try to determine if the remaining issue is structure borne or airborne.
You might try removing the record player from the wall shelf and placing a glass of water on the shelf. Play another source, CD or streaming, whatever you have, and observe the water for movement. Heavy movement will likely indicate structural issues, in which case a TT with a different plinth may help as well as putting a bicycle inner tube under the turntable. It is also possible that a high-pass filter will help, such as the one marketed by KAB. For me that is a last resort as this does have an effect on phase response in the audible range, and adds a set of interconnects, but in some instances it is a perfect cure that eliminates the problem.
If it is airborne, then you have to look at moving the turntable to a place that will excite it less. Play a CD with heavy bass and move your head where you might site the turntable. You will hear areas of greater and lesser bass accentuation. See if you can move the turntable to a place that has less bass accentuation. That will often help.
I hope that helps a bit.
What type of phono preamp do you have? You may be able to make some adjustments that may help fix the problem.
Since the problem started when you added the sub, I don't see why the problem can't be with that also. How do you have it connected to your system? If you're using an LFE output on your preamp, do you also use the LFE input on the sub?
Another avenue of concern is a grounding issue. If the turntable is not running, I'm wondering if feedback is the problem. Do all the grounding tricks....eliminate the 3rd pin of the sub via a cheater, reverse the plug, using an extension cord, plug the sub into an outlet at the other end of the house, etc. When you find the troll, you then can figure out how best to fix it. Let us know....
I'd recommend waiting one year till new Technics DD. It may be sold at your price range hopefully.
Any possibility to add a subsonic filter? Lots of budget phono Pre amps have them too.
Thank you everyone for your ideas.
It's an odd thing.
As I mentioned, just having the needle dropped on a stationary record and turning up the volume level is enough to kick in the rumble. The room is perfectly silent while doing these test.
What's interesting is that I can actually dial the volume up louder when the patter is spinning and music is playing.
If I turn up the volume with the tonearm in it's resting place, I get zero rumble/woofer flapping. I use a zero dust to clean my stylus. If I lower the stylus onto the zero dust, and then increase the volume I also get no rumble/woofer flapping.
The subwoofer is connected to my Anthem MRX HT receiver via LFE connector. No issues with digital sources of course. My phono preamp is a Rega Mini Fono A2D.
I created a custom grounding wire awhile back that connects the bearing well on the Rega to the Mini Fono A2D. I found that it eliminated some HUM I get in the Winter when the air is very dry. Connecting and disconnecting the wire makes zero difference.
If the issue is a grounding problem, it seems like the source is the tonearm itself. The RP1 doesn't have a separate ground wire for the arm. It's supposedly grounded through the RCA connector.
It is acoustic feedback from the sub into the turntable body...bearing...platter...stylus. Put a slab of granite under the TT on the wall shelf.
"The subwoofer is connected to my Anthem MRX HT receiver via LFE connector. No issues with digital sources of course. My phono preamp is a Rega Mini Fono A2D."
You should only use 1 LFE connection. If you connect IC's to the LFE out on your HT preamp, the other end should go to the line level input on your sub, not the LFE input. Try that first.
You may also want to try lowering the gain on your phono preamp, as well as checking the gain on the channel you are plugging it into. A lot of theatre processors have that ability. Also, I'm assuming that you are using the analog connections on your phono pre, and not the USB option.
Your current table and the ones you list are all non-suspended subchassis designs. A suspended design might work better in your room.
"It is acoustic feedback from the sub into the turntable body...bearing...platter...stylus. Put a slab of granite under the TT on the wall shelf."
I have a 30lb two inch thick slab of Maple between the wall shelf and the Rega. The rega sits on top of four Herbies tenderfeet instead of it's normal three stock feet.
The Martin Logan Grotto i subwoofer is the only thing connected to the LFE output on the receiver. The phono preamp is connected to the receivers analog (AUX) input. The only time I've ever used the USB is to connect the preamp to a computer for recording.
I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port.
"I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port."
You can sometimes control each input on a HT preamp individually. I keep coming back to this gain issue because 5.5 MV seems pretty high. I haven't uses a MM cart in years, so I guess that could be normal for them. The highest output cart I can remember having is a DV 10x5 at 2.5 MV, and you needed to set the phono pre on MM to use it.
Maybe try fooling with the xover on the sub. See if you can set it to have a limit on how low it will go. It may be having a difficult time with really low notes, and that distortion is somehow effecting the system. Also, it wouldn't be a bad idea to try connecting the sub normally, without using the lfe, and any other type of EQ/Room Control processing.
Some questions that may help the troubleshooters :
- Is your shelf between the speakers or in a corner?
(Placing it halfway along a load-bearing solid wall will minimise the effect)
- How far away is the T/T (& cartridge) from the nearest speaker/subwoofer?
- Is the floor suspended?
- Is the shelf wall load bearing?
One scenario would be to try distancing the T/T and using a longer interconnect to your main amp but since that may involve moving the shelf (or the loudspeakers) I suspect the best WAF solution is another table? (I think you've pretty much resigned yourself to that solution anyway?)
If all else fails a good option would be a suspended subchassis T/T. (Not sure if any of your stated choices are?)
These are often purported to be able to be placed directly on top of a full-range floorstander and still be able to play successfully without interference (albeit not the ideal choice of location!).
Try getting rid of the maple slab. The design of the Rega turntable is based on very low mass evacuating energy as quickly as possible. You have essentially defeated the design by adding mass which is why the granite slab won't help either.
After removing the slab, experiment with, and without, the Tenderfeet.
Maybe this is the answer. It doesn't have a shelf at all...
Your sub is to loud, turn the volume down.
"Your sub is to loud, turn the volume down."
Your probably on to something there. I have it set where I like it for digital sources. I can decrease the volume on the AUX input so I'm going to play with that.
The wall shelf I purchase is not the Rega brand one with the cups that line up with the feet. That shelf wouldn't work for me due to how it's built with the bracing. With the shelf I have now, I was able to slide my buffet directly under the table. I did try a lightweight bamboo cutting board before the maple slab. The maple slab seemed to reduce the flapping better.
I'm at the point where I feel like I have three options.
1) Purchase a new TT (one of the tables I mentioned in the original post). I probably going to do that anyway. I purchased the RP1 to see if Vinyl was something I wanted to get into, and now I have over 500 LPs. I'm here to stay.
2) Pickup a Phono preamp w/subsonic filter, or purchase a KAB RF1. The RF1 just seems expensive at $179 when I can pickup a Pro-Ject Phono Box DS for a little more money. I'd Consider the Cabridge Audio 651P as well, but I don't know the specs of it's subsonic filter (where it starts to filter and how steep of a slope).
3) Forget using the subwoofer with Vinyl. It might come down to this in the end.
"2) Pickup a Phono preamp w/subsonic filter, or purchase a KAB RF1. The RF1 just seems expensive at $179 when I can pickup a Pro-Ject Phono Box DS for a little more money. I'd Consider the Cabridge Audio 651P as well, but I don't know the specs of it's subsonic filter (where it starts to filter and how steep of a slope)."
I believe your sub already has one. Use it to block the lowest frequencies. It will probably take some experimenting to find the right setting.
Jeff, even with loudspeakers that have an early bass rolloff (bookshelves, electrostats etc), Users generally feel the use of an external sub-woofer is unhelpful when it comes to music.
Sensibly applied it is, however, possible.
My Martin Logan Vantages feature a 200W powered integral sub-woofer which operates from below 34Hz up to 400Hz. In order to integrate the sub properly with the room and the panel I deliberately attenuate the bass by -4.5db before it starts to appear seamless. (This despite the speakers being 4.5ft from the walls)
I find less is more in this case.
For me it isn't just a matter of overcoming feedback but aiming for a balance in which the lowest octaves don't overwhelm the room in an audibly unnatural way?
A quick update. I had the stylus sitting on a stationary record, and turned the volume up to the point where the subwoofer started to slightly pump and the sound (low level rumble) was just audible. I gently put my hands under each side and exerted a slight lift upwards. The rumble went away. I didn't have the TT completely lifted off the maple shelf, but I was in essence making the TT lighter.
Now all I need to do is create an forced air cushion that would suspend a TT in the air. Or a device that modifies the higgs field around the TT to lower it's mass.
Seems a better built TT might be an easier option? :)
As I said above, bicycle inner tube. But you seem to prefer anti-gravity guns and new turntables.
You moved the T/T while the stylus was down on a stationary platter? Danger Will Robinson!! ;^)
Your wife should have warned you to tape the platter first before engaging in these shenanigans ;^)
You need a personal Force-Field to prevent you accessing your turntable. :)
Joking aside, not exactly air. It was supported by you while your feet were on the floor. Effectively 2 forms of support in parallel, you plus the rubber feet on the maple block, one(you) more massive than the other.
In theory this should have been worse!
I'm wondering if your stylus bounced up in the air slightly while you were lifting????
Between the table combos listed I would prefer the scout.
If you want to buy a new TT, by all means get one. But you shouldn't be forced to get one over an issue like you are having. If you try some different settings on you sub (including not using the LFE connections at all), and some isolation devices, you should be able to get everything working.
"As I said above, bicycle inner tube. But you seem to prefer anti-gravity guns and new turntables."
I'm willing to give an inner tube a shot. I did try some packing air pockets under each of the three feet, and it really didn't seem to make much difference. They are the things that they use in shipping instead of packing peanuts.
Would a 12" diameter work? The RP1 has a footprint of 17.5x15. I can also get a 14" tube as well.
"A quick update. I had the stylus sitting on a stationary record, and turned the volume up to the point where the subwoofer started to slightly pump and the sound (low level rumble) was just audible. I gently put my hands under each side and exerted a slight lift upwards. The rumble went away. I didn't have the TT completely lifted off the maple shelf, but I was in essence making the TT lighter."
Try that again. Do everything exactly the same, but don't lift.