low frequency noise from warped records

[DaHaq]

I'm new to vinyl and I recently acquired my furst turntable, an old Technics SL-1300. I notice when I play slightly warped records my speakers must translate the warping as extreme low frequency noise because, although I don't hear anything, I can see the woofers fluttering back and forth. This doesn't seem safe for the speakers, and I'm wondering if there's any way to fix the problem besides just not listening to warped records? Right now i'm using the phono input on the back of my onkyo ht receiver. Do higher quality phono preamps address this issue with a filter?

Thanks

[royphil345]

http://www.kabusa.com/rf1.htm#CTOP

[DaHaq]

it says to place it between the phono preamp and control amp...I'm wondering how this would work since my phono preamp is integrated in my receiver....Maybe I just have some upgrading to do ;D

[royphil345]

it says to place it between the phono preamp and control amp...I'm wondering how this would work since my phono preamp is integrated in my receiver....Maybe I just have some upgrading to do ;D

Good eye!!! Don't know why some people have more problems with subsonic noise than others. Could try changing the mass of the tonearm (add a little weight, then readjust) Better isolation of the turntable may help. Different cartridges probably react differently. Think I remember having that problem when I was using an Audio Technica 440ML. Now I'm using a Shure M97xE and don't have any problems. Maybe that little dynamic stabilizer brush really does something? Haven't been tempted to go back to KAB and buy that subsonic filter lately.

[slate1]

Woofer "pumping" is a very common and, for the most part, harmless problem with vinyl. It most probably isn't going to harm your speakers but your amp will have to work a lot harder while this is taking place.

The most common factor is poor arm / cartridge matching - what cartridge are you using on the Technics?

[DaHaq]

The cartridge says MG Grado, its the same cartridge that was in the TT when I picked it up at a garage sale for $25. I was wondering if I should get a new cartridge, but it sounds great to me (I can definitely hear the improvements over digital) so I figured why bother. If a new cartridge would fix the woofer pumping issue, however, I might be interested. You say to adjust the weight on the arm? I've been wondering what the knob on the arm was for, and the knob sitting next to the arm base as well...I have no idea what those are for! An explanation would be greatly appreciated. Thanks again!

[royphil345]

The dial on the back of the tonearm is the counterweight. To set it properly, rotate it counterclockwise until the tonearm balances and floats just a bit above the arm rest.
While holding on to the back part of the counterweight, rotate the front part (dial) until it reads 0. Then, rotate the whole thing clockwise and set it to the recommended stylus pressure for the cartridge you are using. I know that you probably don't know what that is. Unfortunately, either do I but 1.5 grams would be a good place to start.

If you listen closely, you can usually hear when the tracking force is set correctly. Too little force and the highest highs will be stressed a little bit. Might sound a little "thin". When the tracking force is set too high, the midrange will be stressed and the music will sound a little too "compressed". The proper force for that cartridge should be somewhere between 1.5 and 2.5 grams.

The other dial is the anti-skate setting. The grooves of the record carry the stylus towards the center of the record. this causes the stylus to hit the inner groove wall of the record harder than the outer groove wall. The anti skate should be set the same as the tracking force being used to counteract this. Helps the stylus track better, helps keep the left and right channels in balance, and prevents excessive wear on the inner groove wall of records and uneven wear on stylus.

What I was saying about changing the tonearm mass is that you can try to add a little weight to the tonearm by adding a small metal plate to the top of the headshell. You could use a little ball of that tacky poster hanger stuff instead as an experiment. Then, reset the 0 point on the counterweight and try that. You get the same stulus pressure, but a different tonearm mass which will cause it to resonate at a different frequency. Sometimes this will help to clear up problems. If your cartridge wants to be on a lighter arm, there's not much you can do about that.

If you have a level, making sure your turntable is perfectly level is a good thing.

[DaHaq]

Thanks for the instruction, royphil. I tried the counterweight at various values and decided 2.5 sounded the best to me. At lower values the music seemed to lose detail and atmosphere. I also tried placing a quarter on the cartridge to raise its mass and reset the counterbalance, but this seemed to make no change in the sound and woofer pumping still occurred same as before. Oh well, at least I know how to set the counterbalance and skate properly now. I'm sure sometime in the future I'll upgrade to a seperate phono preamp and then I can get a rumble filter. For now, as long as my speakers aren't being damaged, i'm happy.

[royphil345]

If it's only happening on warped records and the woofers aren't close to bottoming out it's nothing out of the ordinary. The 2.5 grams is probably about right for that cartridge. Noticed that the tip looks a little thicker than newer models that track lighter. You're a pro already, setting your stylus pressure by ear!!!

Congrats on purchasing the Technics 1300 by the way. Nice looking table. Came close to buying one myself a few times. Wouldn't jump into upgrading anything if you like the way it sounds now. Don't know if you can still get a replacement stylus for that cartridge though. Could go to the Grado site and see if there's a way to send e-mail. Maybe send them that nice pic of it.

[thepogue]

I got the same thing going on w/my set-up. I just upgraded to a Linn LP12 basik + Grado Gold cart (from a Tech 1700 mkII) and the strage thing for me is that it's only on me left speaker....shes not bottoming out at all...and I'm running 2 555 mkII Adcoms so I'm not to worried 'bout no having enough power...but it's still freaky to see. Is there a room treatment or positioning issue here also? BTW it's happening a bit less now with the Linn...but shes still wabblin' lime heck!

Thanks and once again good post.

Peace, Pogue

[DaHaq]

What does "bottom out" mean? I feel like an idiot since I see the term everywhere and still can't figure out what it is.

[thepogue]

your cones (in your speakers) are suspended by rubber or foam (called surrounds)...if these are over extended but puting too much power to them then bottom out frrrrump!

thats my best take on it...I know not very technical but I think thats the jest of it


Peace, Pogue

[E-Stat]

What does "bottom out" mean? I feel like an idiot since I see the term everywhere and still can't figure out what it is.

BTW, you are experiencing "warp wow" which has been a potential issue with vinyl for decades. A subsonic filter can help. I'm fortunate in that I have an unusual linear tracking tonearm whose tube is extremely short and is able to track warps just fine.

Conventional moving coil speakers have a cone attached to a paper sleeve with long coil of wire. There are two suspension elements: the surround you see on the outside of the cone and the "spider", a flexed paper affair behind the cone. Bottoming out is when one of the suspension elements, usually the spider attached to the voice coil, runs out of movement like bottoming out a car suspension on the bushings.



rw

[royphil345]

I got the same thing going on w/my set-up. I just upgraded to a Linn LP12 basik + Grado Gold cart (from a Tech 1700 mkII) and the strage thing for me is that it's only on me left speaker....shes not bottoming out at all...and I'm running 2 555 mkII Adcoms so I'm not to worried 'bout no having enough power...but it's still freaky to see. Is there a room treatment or positioning issue here also? BTW it's happening a bit less now with the Linn...but shes still wabblin' lime heck!

Thanks and once again good post.

Peace, Pogue

Can't explain the 1-channel thing. Better positioning or isolation of the turntable would only help if you were having feedback problems. If you notice the problem gets alot worse at higher volumes, you're probably getting some subsonic feedback. Don't know if you could be getting feedback in the left channel because the left speaker is closer to or aiming towards the turntable? Or would the turntable picking up vibrations from 1 speaker cause feedback in both channels? That's a real brain twister... Maybe someone knows? I sure dont. Haven't learned much about room treatment either. Finally got my system to a point where I really enjoy listening to it. Hope it stays that way without me having to buy anything else or tweak anything else... I'm definitely learning that ignorance is bliss in this hobby!!!

In the old days, alot of receivers and EQs had built-in subsonic filters. They just don't care about us vinyl junkies anymore!!!

[Ray H]

Can't explain the 1-channel thing.

Antiskating set way off whack?

[thepogue]

as far as tracking...and to be honest I'm not sure that would do the wobbly thang...


Pogue

[risabet]

The problem is in the combination of your cartridge and tonearm, the system resonates in the same range as record warps. Are you using a moving magnet cart. or a moving coil (high output)? If you have a MM cartridge (as I suspect) switch to a HOMC, the lower compliance should raise the resonant frequency of the arm/ cartridge system to above the warp frequency limiting the pumping of the woofer and the wasted power that your amp uses to move the woofer. Avoid the use of subsonic filters as even the best of them slope up into the audio band and phase shift the signal.

[DaHaq]

I just replaced the Grado with a Shure M97xE cartridge and the woofer pumping phenomenon has been greatly reduced, if not altogether eliminated. The sound from the Shure seems more detailed as well. Just wondering, if anyone else uses the Shure, do you typically use the dynamic stabilizer brush or no?

[royphil345]

Yep. Have a M97xE and a V15Vx. Use the brush on both of them. Think the M97xE is impossible to beat at the price. Love mine. Actually think it sounds better than the V15Vx. The V15Vx seems almost as capable in the detail / frequency range department as a moving coil. Seems like the super- flat frequency response the older V15s were famous for was compromised to pull it of though. Just doesn't sound that musical to me.