Strange Tonearm Tweak. Long


As you all know, I am a little different. I like to read and study stuff like tonearm technology. I noticed that some of the better unipivot designs have employed "outrigger" style outboard weighting systems on their arms, that work like a tightrope-walker's balance pole. This not only balances azimuth, but also gives the arm better stability to lateral deflections from the cartridge suspension, so the arm is not moved when the stylus is pushed laterally by the groove information. I began to think on this, and I wondered why no gimbal-bearing arm makers are doing this. Surely since the vertical plane rides on a vertical axis bearing, there is still some chance for the arm to be laterally deflected by the stylus, when the stylus should be doing all of the moving, not the arm. I think that this is why they use heavy arms, but a heavy arm in the vertical movement plane is not good for tracking. A heavy arm in the horizontal movement plane is good for resisting sideways deflection that would impair pickup function.

So I decided to try increasing the mass of my tonearm in the lateral plane, while keeping it light in the vertical plane, by the use of "outrigger" weights, just like a unipivot does.

I bought lead fishing weights that looked like long rifle bullets(just the lead part) They were about an inch long and about 3/8" diameter, and weighed 12 grams each. I drilled into the bases about 1/4" and press-fitted them onto the nuts that hold the arm into the bearing yoke, so they stuck out straight sideways, like sideways spikes. This put the weight out pretty far to the sides as outriggers, and kept the weight centered exactly around the bearing pivot axis so it did not increase the vertical mass significantly, but it did very slightly. It did not influence the tracking force at all.

So now the arm had outrigger stabilizers on it in the horizontal plane of motion.

I put on a record and sat down to listen. Let me tell you, fellas, this was a mind blower. I have never heard this much information come out of a cartridge before. I heard sounds on records that I had listened to for 30 years, and never knew those sounds were on the record! And I have had some pretty good analog gear in my time. And what I didn't own, I heard at the audio store I worked at. This is the most astounding mod I have ever heard on a tonearm. And it cost me $1.49 for the fishing weights, and I got 3 extras.

The only slightly negative thing about it, is that it increases the anti-skating force, so you have to cut that back a little, and if you have some marginal scratches that might skip, they are more likely to skip with this mod, due to the resistance to sideways movement provided by the outriggers. I had this happen once last night, but I didn't consider it a problem.

But the increase in dynamics, and detail and overall sound quality is astronomical. It blew me away.

I have a DL103, which is a very stiff cartridge, and it may be that this is not needed for a higher compliance cart. But, I think that it would be good for anything that is medium or lower in compliance.

The key to it, is that it only increases the resistance to sideways movement, without interfering with the effective mass of the arm, or the vertical swing movement that needs to stay light to track warps. I played some warped records with this mod, and they played just as well as without the mod, except they sounded better.

I have a pretty good analog setup now, but I can say without reservation, that this mod made my rig sound better than any analog rig that I have ever heard in my life. I have never heard a Rockport.

Stabilizing the arm against unwanted lateral deflection increases the information retrieval and dynamics by a very large percentage. If your arm is not set up like a Rega style arm, then you can glue a 1 ounce long rod across the top of the bearing housing(sideways) like a tightrope-walker's balance pole. Use lead if you can, it won't ring. You don't have to do any permanent changes to your arm that might wreck its resale value to try this out. If it has anywhere near the effect on your system as it had on mine, you won't be taking it off.

It may come close to the movement of your cueing lever, so make sure you have clearance to use it. Mine was close, and I have to come in from the side now to use the lever, at the end of a record. That is fine with me! This was a major, major improvement in the sound of my rig. It is staying permanently. As in "forever".

If you are a little tweak-oriented, and not afraid to do stuff like this. You should try it. It will knock you over.
twl
Finally it plays!
My TT, born as a string driven unit, build on a
rectangular shaped plywood with cadberg and scheu
pieces, now is a nice drop-shaped, multi sandwich,
lead filled unit.

It's suspended on air (inner tube). The
motor unit drives the platter "crossing" a flywheel.

The arm, now rewired, sounds much more precise and free of resonances.

All in all, I'm very satisfied. LP sound quite good.
I've only a residual hum (apparently not related to
arm grounding, but I still have to investigate).

Another 250 is sitting, waiting for a hanging cw test...

Ciao,

Stefano
Stephano directed me to this thread. I'm glad he did :)

I have a DL103D on a modified RB300 arm (expressimo back end, no VTF spring, Cardas wire, no plug in arm pillar base, VPI VTA adjuster, planed underside of headshell and end of arm tube).

For years, my general approach to upgrading and tweaking has been to identify each individual weakness and fix it. As a result, my tonearm has been setup to reduce the presence region resonance/shrillness in this arm/cart combination. I've applied several suggestions from Thorsten (decoupling cart from headshell, lead tape around armtube at 1/3 length) and set VTF and VTA to reduce the shrillness.

After reading a bit of this entire thread, I got a 3/4 ounce "lead substitute" weight, cut it in half, drilled the ends, loaded them with modeling clay (temporary glue) and stuck 'em on the axle nuts. There was an astonishing change as all previous customers have reported.

- large increase in bass resolution and extension
- soundstage is more solid, bigger, paradoxically with less well defined instruments
- shrillness mostly gone (yea!)

Then I noticed that the top octave or two were gone.

So I decided to set up the parameters that are tuned by ear -- VTA, VTF, and anti-skating -- again. Azimuth, overhang and offset are set correctly. Instead of setting these by ear to reduce the shrillness while maintaining a decent tonal balance, I followed a method that's new to me. Basically, you set VTA to get best focus on a mono vocal record, then set VTF to get best dynamics and realistic tone, then set anti-skating to get equal dynamics in both channels. See this post by Bernhard Kistner at http://www.audioasylum.com/audio/vinyl/messages/45126.html.

First, I got some 1 oz. lead weights and redid the outriggers. Then set the arm up twice. After the first go round, there was an upper bass/lower midrange boost. This was due to the lead band around the arm. So I removed it and started over.

As things have turned out, there is now almost no distortion and the tonal balance is pretty much as it should be with only minor HF rolloff. Many many records that were really "zippy" and sibilant are very clean and natural now. Most bass is much tighter. Unfortunately, some old bass-shy Mercs are even more so, though the definition is stupendous.

I'd like to throw my hat into the amateur physicist ring and open up an issue.

Several people have noticed the change in soundstage similar to what I described. I believe that non-identical moments in the lateral and vertical planes are the culprit, causing crosstalk between the channels that has an unknown phase relationship to the signal in the originating channel.

If the cartridge body was perfectly stationary, azimuth perfectly set, and the groove was carrying a signal in once channel only, then the stylus would be moving in a plane at 45 degrees to the record, perfectly aligned with the generator for that channel. Now, if the cartridge is allowed to move in the vertical plane, then the stylus motion, relative to the cart, would be in a plane that is no longer aligned to the generator. This motion, as a vector, has a small error component in the plane of the other channel's generator. Depending on the actual motion of the cartridge in the vertical plane, this error component may be in phase with the dominant signal, out of phase, partly delayed, and this relationship may vary with frequency, arm resonant behavior, the behavior of the as an oscillating system over time, etc.

Fixing the arm in the lateral plane by raising the lateral moment, while the vertical moment stays relatively low to allow the arm to track warps, is equivalent to the situation I just described.

Thank you TWL for the mod.

- Eric, three years too late to this party
Hi all,
Eric many thanks for sharing the VTA/VTF/Antiskating procedure!

The hanging cw trick is still waiting...

Woud you mind explaining the Thorsten advice about cart/arm decouple? Is it similar to Len Gregory "The isolator" principle?

Stefano
just put this on the lenco thread. Thankyou Twl. simply astonishing... :

Ok guys, here's the result on the RB300. IT WORKED! FIRST TIME! Ye gads. Dodgy phonos and no earth from the tonearm, and it does quite nicely. Now, with Michell Arm weight mod and my faithful Denon dl103r going through cardas cartridge pins into 4 feet of cardas tonearm wire, straight into the stepup, without the wire having run in for more than 1 hr it sounded ok, not brilliant, but ok. Bare in mind i'd just removed an OL Silver with all its superior price etc, that I'd been playing nonstop for a year plus. What i could now hear were vibrations (sibilence I think is the word) in the arm. Bass notes were muddied , imaging was lost, sparkle and prat werent there - Basically an inferior vibrating arm. Oh well, I need the money.

Then lightening struck!

I know, thinks I - I've got some of those fishing weights and bluetack that TWL was going on about, namely his hi fi mod!. Why not wack em on and see what happens. 2, yes 2 minutes later i had pressed the weights on with a liberal splodge of the blue tack, wacked a record on, and....

Bloody hell, i've got my OL SIlver back!!! This is not insignificant. This is not minor, this is £400 better and some. You know I think it might even be better than the OL Silver! What a laugh. All you RB300/RB250 people out there, hear me well. This is F.....g A! TWL should be knighted, rolled in clover, miss USofA'd to his heart's content and some. I'm in the next room typing this and it sounds better! Clearer, more focussed, more in the room.. just gone in for another listen, and wow it s cookin'. Lenco slam in spades. I'm a happy bunny. I've got a feeling we're heading towards OL Encounter land, as TWL himself said. Good thing I didnt try this on the OLSilver, I'd be weeping right now. Is anyone hearing what i'm saying... And the cardas cable still has to burn in. Hee Hee.
Gilbodavid,
Very happy you liked the mod.
It is pretty much a requirement when using a cartridge like the Denon DL103R on a Rega-type arm.

Every so often, somebody actually tries this mod, and the response is aways one of "amazement".

It's really just a very simple application of basic principles.