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Freako
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Joined: Jan 17 2010 - 8:29am
PU tweaks

Hi all! I am new to the Stereophile forum, and I would like to present 2 tweaks I have done recently. The first is about filing off excess material from the tip of my cantilever, and the second is about isolating the PU itself from the shell/tonearm.

Some might say that removing a few milligrams of mass from the tip of the cantilever would have no effect whatsoever. However, when the tip of the cantilever is moving 20.000 (or more) times each second, the mass removed might present quite a considerable mass. In removing the excess material from the cantilever, the resonance of the cantilever will be raised, which IMHO is a good thing in itself. Furthermore, the PU will be able to deliver a slightly more "free" and relaxed treble. Some tweakers report that the transients throughout the whole range of frequenzies sound more natural also, which I am not entirely sure of. This probably depends on the properties of the PU, and brightly sounding PU's would of course not benefit from this tweak, as they might sound even brighter after applying this tweak. I did it on my Denon DL103, which got to sound a tad bit brighter and quicker after doing this. I especially recommend this for the "darker" sounding PU's.

Above I have made a drawing of the cantilever seen from below. Sorry about the foreign lingo. The pink area shows the removed excess material. The green arrows show the direction you should grind, and PLEASE BE VERY CAREFUL! Never EVER grind from the tip against the base of the cantilever, always from the base towards the tip. Use sand paper no. 800 or the fine side of a "cardboard" nail file. Do not use a metal file. A very gentle pressure (like the weight of the file itself) is more than enough. Use more pressure, and you'll most likely bend or damage the cantilever, thus saying goodbye to your PU. Use a strong magnifying glass to monitor your progress several times during the process. On some (pricier) PU's there's probably no excess material to file off, and/or the cantilever itself may be made of some sort of crystal, why this tweak may not be possible to apply at all. But if you have a cantilever of say aluminum or maybe boron, a steady hand, and about half an hour to do this, you should get a better top out of the PU. If in doubt, try removing half the excess material, mount the PU, and listen for improvements. Remember to adjust it properly (overhang, HTA and VTA). I have to add that I cannot be held responsible for you damaging your PU, just to point that out. So be very careful! You may want to try this on an old, worn out cantilever just to get the feeling of it.

Here's the cantilever seen from the side. Be careful not to remove the blob of glue that holds the stylus tip on to the cantilever. Some tweakers have reported that up to 75% of the blob of glue can be removed with no negative side effects, but I will not recommend doing so.

Also be careful not to file the stylus tip itself. It is probably as hard as the material of the file, or even harder, but you don't want to damage the tip. In other words, extreme caution, a safe hand and a little patience, and you have yourself a better sounding PU.

The next tweak is much easier, but provides an even more audible improvement. When a low compliance (moving coil) PU is in use, it returns a lot of vibrations (energy) to the tonearm, due to it's rigidity. If the tonearm is not sufficiently damped, which (IMO) very few are, the tonearm will transform these vibrations into distortion that may be heard as a messy and less clear soundstage, a slightly muddy bass reproduction, and a lack of "black" background. Strangely enough these negative properties are often not noticed until they're gone!

I found a small piece of damping foam rubber in my "leftover" box, where I keep screws etc for PU's. This was about 1/20th of an inch thick, and self adhesive on one side. In lack of such material you may use a thin slice of cork or rubber instead. No need to use glue of any kind, as the PU and the shell should be tightened together just like they normally are.

This piece of damping foam rubber I cut into a shape that fit the top of my cart, and slipped it in between the cart and the shell. I tightened the screws just enough, so I could still move the cart. Then I mounted the cart, readjusted the counterweight, HTA, VTA and overhang, and tightened the screws as much as I dared without destroying anything. Some hardcore tweakers do in fact glue the cart to the headshell, but I didn't want to go that far. Some also protested because the screws would still "tie" the vibrations of the cantilever/PU to the shell, thus providing a path for the vibrations moving back into the tonearm. Maybe so, but I still experienced a very audible change that I can only describe as a major improvement.

The sound after doing this, was much more "out of the box", with much more "air" around the musicians, and a much quieter background of the soundstage. All in all, a move towards "high-end" reproduction IMHO.

If any of you guys feel like trying, please be careful, as I would feel sad being the reason why any of you ended up ruining a perfectly good PU. My equipment is good hifi and some of you with other equipment (or taste) may experience these tweaks on a whole different level than I do, or maybe even dislike the sound achieved from these tweaks. It's up to you to make the decision, and I sincerely hope that you - just like I did - will be able to get more enjoyment from listening to your music, after applying these tweaks. Have fun!

dbowker
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Joined: May 8 2007 - 6:37am
Re: PU tweaks

Interesting- but don't you think the cart manufacturer would remove that section if it were extraneous. And I don't know which cart you tried this on, but mine is around $600 and I can't imagine doing mods that scream of bent cantilever! Yikes!

Freako
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Joined: Jan 17 2010 - 8:29am
Re: PU tweaks


Quote:
Interesting- but don't you think the cart manufacturer would remove that section if it were extraneous. And I don't know which cart you tried this on, but mine is around $600 and I can't imagine doing mods that scream of bent cantilever! Yikes!

Well, some do remove it and some don't. It's plain to see if you have a magnifying glass. I did it (as stated) on a Denon DL 103, with a good result. As I also (kind of) stated, pricier PU's already have this done, or have types of cantilever that probably can't be filed on with a nail file. OTOH any "dark" PU on the cheaper side will most likely benefit from this tweak. Thx for replying

Buddha
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Joined: Sep 8 2005 - 10:24am
Re: PU tweaks

You are a braver man than I.

Fascinating idea, by the way!

It honestly gave me the audio shivers as I was reading about it. Your post is greatly appreciated and I admire your creativity.

Freako
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Re: PU tweaks

Thanks Buddha! I appreciate your reply It's not that big a thing anyway to file away on a cantilever, neither the improvement nor the procedure, but on my PU, I can very clearly recognize an improvement, especially when considering both tweaks at the same time

Elk
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Last seen: 5 months 2 weeks ago
Joined: Dec 26 2006 - 6:32am
Re: PU tweaks


Quote:
It honestly gave me the audio shivers as I was reading about it. Your post is greatly appreciated and I admire your creativity.

Me, too!

But well done.

Freako
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Last seen: 5 months 6 days ago
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Re: PU tweaks

Thx Elk

Freako
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Last seen: 5 months 6 days ago
Joined: Jan 17 2010 - 8:29am
Re: PU tweaks

But the damping of the PU from the headshell may easily benefit most PU's. The improvement here was (again IMO) remarkable, so go ahead and try it! It's fully reversable and very quicly done...

Some guy even "invented" an isolator to do the job, but I think adding metal to the headshell/PU seems a bit too far out, considering the weight increasement.

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