Arm resonance

[Makymak]

Hello!

How can we mechanically reduce the low frequency resonance on a given tonearm - cart setup? I'm talking about the low frequency ramble which occurs when playing a warped record.

"Mechanically" I mean what mods can be done on the tonearm/shell/cart instead of the easy way to use a high pass (subsonic) signal filter.

 

[vince666]

some carts, i.e. the Shure M97xE i have here and a few others, have that inbuilt brush which is actually a dynamic stabilizer/damper to just deal with this problem... and, unless the warp is just too severe, it works just nicely.

I believe that would be a purely mechanical way to deal with this problem...

and, btw, I have no idea if there are other solutions.

at first, while simply reading your thread's title and before reading your actual post, I was assuming you were talking about the obvious resonance issues which happen when the tonearm's effective mass and the cartridge's compliance don't match nicely... so that would be another thing to check but I believe you are just OK about that, otherwise you'd have resonance issues even while playing a record which is not warped.

 

[AngrySailor]

The replacement carts for the Shure V15-VI such as Jico have the brush but apparently are only a sweep brush with no damping like the originals. I have one of each kicking around but I’m not home rn to compare the brush compliance...

 

[laatsch55]

8891XJ needs to chime in here...

 

[Makymak]

I was assuming you were talking about the obvious resonance issues which happen when the tonearm's effective mass and the cartridge's compliance don't match nicely...

It could be that, too? Damn, it's all new to me, I'm in the tt sports only a year now. When talking about wrapped records, I mean slightly. At normal listening, I can't hear the rumble but when recording on cassette, the signal saturates when the stylus passes the slightest wrapping on the vinyl. It happens only on the outermost part of the vinyl, let's say on the first one - two minutes. I have to record on low level (up to Dolby level) to avoid this saturation. And it happens with almost all my decks. The only quite immune to this problem is the RS-B965 which can tolerate higher levels before it saturates.

 

[Makymak]

The solution I use on the Shure M91ED is to place a small piece of felt over the cantylever to reduce the dumping and it works perfectly. But I know this is not an appropriate solution and I don't want to apply it on my Stanton 681EEE. So, I'm seeking for a correct solution, if any.

 

[8991XJ]

All things the same, adding mass to the cartridge will increase the resonant frequency of the arm.cartridge combo.

I don't know if we are talking about this specifically as it may be another poor cartridge output due to the warps. Not knowing what gear is involved with the issue to determine what the starting resonance frequency is for those components limits the ability of anyone to answer questions. Also what kind of warp, frequency and amplitude.

Time for one of that $1700 record flatteners. Not that this is the way to go. That is a lot of money to spend for the few warped records we have.

 

[J!m]

In was going to suggest altering cartridge mass as well. It is literally a balancing act, and just changing cartridge hardware material can be enough to do it. Going from nylon to aluminum to titanium to stainless (or brass) all can increase mass at the headshell slightly.

VTA should be confirmed as well. Shims (light and heavy) exist to sort that out.

Finally, what is the condition of the suspension? Old MM cartridges get new stylus’ but rarely new suspensions…

 

[Makymak]

It's my Denon SL-5DFF for which I don't have any further info! The cartridge is a Stanton 681EEE with new stylus and suspension (replaced as a whole assembly).

If I understand correctly, adding some weight to the shell will rise the frequency. So, this might be a solution if the frequency rising is accompanied by amplitude reduction. How many grams would be a good start?

PS. As you already have understood, I'm completely ignorant of all these. Thank you for your kind responses!

 

[J!m]

I would start small. Add one gram to start.

I don’t have any Stanton cartridges but I believe they are on the heavier side already.

If you do end up needing to move the counterwraifht further out on the stub, you might benefit from a heavier weight. Because moving the weight further trim the pivot can I duce additional resonance. It is also beneficial to have the center of mass of the counterweight in line with the stylus tip- which nearly always means “underslung”, or under the stub.

Especially with a straight arm, vibration will reflect off the weight and feedback into the system.

But start out getting the resonance under control first, then we can move forward.

 

[Makymak]

Thank you! It seems the counterweight has much travel to counter several weight addition. My tonearm is an "S" shaped, I don't know what impact it has. I will start with a gram as you suggested and see how it goes.

 

[J!m]

S shape is a bit less likely to have a second resonance, because the line is not straight to the counterwight (only benefit of an S or L arm I can deduce). they tend to be heavier slightly due to the added length to accommodate the bend(s).

If you have a test record, that can point out the resonance precisely. I had calculated mine (formulae on vinyl engine), but it gives a range of course, my test record confirmed I was "in the calculated range" but specifically, it resonates at 10hz in my case.

My lost document included a shit-ton of such calculations, because when you are designing the arm, you need some predictions in place long before empirical testing can happen... You can make the change, re-align and re-balance and then test empirically. More accuracy and less math...

 

[8991XJ]

You have a medium mass tonearm and both of your cartridges would work best in a lower mass arm. The Stanton and Shure are both on the higher compliance side. Adding mass may keep the arm in the groove but I'm concerned about the rumble and when it shows up. If it could be induced by a speaker being too close or the sound too loud, maybe. It could be the vertical bearing in your tonearm is not as smooth as it once was.

Is this a problem that has shown up lately or have you changed things and the problem showed up?

Of course, the first thing to do when a tt will not play properly is to completely redo the set up. Verify the cartridge position, readjust the tracking force adding a gram to the total if using the Stanton brush and setting the antiskate.

If you don't have the manual for the table to be able to do these things properly, Maybe a different Denon of the other turntable like yours, same table different manufacturers name has a manual on the web for you to find and use.

 

[Makymak]

The rumble occurs only when the stylus is on the outermost grooves of the record and only when passing the wrapped part. I can see the tonearm resonates; it's like a car going over a bump. It's not heard, though I can't see the speakers' cones if rumble too. I have them in a not easily reachable place.

The problem gets audibly when recording on a cassette. Then the rumble distorts/saturates the recording if recording level is over the Dolby level.

When the stylus passes the first two minutes, the rumble disappears.

 

[Skratch]

Tape a quarter on top of the headshell

 

[Makymak]

Yep, although € speaking here!

Anything over 1.5 grams and the problem gets worse. I have the best results with about a gram added on the shell. But far beyond best. Removing the brush weight makes also things worse. The only solution that cures the problem is making the suspension stiffer, adding a felt over the cantylever (as I already have done with the other tt with the Shure cart). But I don't know the long-term side effects of this solution. I can't hear any sound degradation using the felt, though.

 

[8991XJ]

The problem gets audibly when recording on a cassette. Then the rumble distorts/saturates the recording if recording level is over the Dolby level.

I record at very low volume listening levels with the recording levels set properly I don't want any vibrations from the sound interfering with the playback device. Just a habit I got into decades ago. I play the rig loud enough to be able to do what I need wrt making the recording. Don't know if it ever made a difference as I didn't check it doing it different ways.

 

[Makymak]

@8991XJ I rered your posts and I found that I have to give more information. In my case there is no interference from the speakers as I always record using headphones. The problem was always there, I was given the tt with the current setup, already. The only thing I did extra was to replace the stylus and realign the carts using a protractor.

Maybe the word "resonance" wasn't the appropriate to use as actually my problem is the rumble induced by the record wrappings.

Sorry for any confusion. I'm just learning.

 

[J!m]

Resonance is the correct term.

Which alignment did you use? Bayerwald tends to be slightly longer effective length and that may help shift the resonant frequency.

But it seems the arm and cartridge may not be the best match.

 

[Makymak]

Yes, I used Baerwald.