I agree with Donn below, but I suggest taking things one step further! I have reaped incredible performance gains by appropriating phonebooks from the hometowns of all my favorite orchestras!! Right now, I've got my hands on New York, Boston, and Philadelphia, and am definitely looking to expand my collection!! I can't believe the "you are there" imaging that this has produced in my system!! Even better are vintage phonebooks from the era of a particularly spectacular conductor!! I must admit, I am having difficultly getting my hands on phonebooks from Berlin so I can experience von Karajan's conduction of the BPO in it's full unbridled glory!!!
For this kind of mindblowing improvement, I wish I could give six stars!!!

Specs:cover: blue and red
pages: A4, white, yellow
weigh: #


I´m using a local phone book for a while, it´s only 500 pages so I guess
it´s an "entry level" phone book.
Sound is OK for the money ( 0 US $) but I want to upgrade, maybe a thicker
one ? some people say "the thicker ones are the better"
help me please... ;-)

There seems to be no limit to the tweaks available - try this: remove all pages with the word BOSE on them. The quickest way is just to rip out the pages (works fine for a casual listener like me), but the more sensitive ear may benefit by using an x-acto knife to remove just the offending word. TIP: don't just check music-related pages. Check the auto ads - some manufacturers (i.e. Nissan) promote Bose as an upscale enhancement in some models. And don't forget the single-line entries, not just the big display ads. If you are using white pages (not a good idea based on other postings), take out ALL the Bose listings (it's amazing how many people are named BOSE out there).
Whichever method you use, sit back and enjoy a whole new mid-range experience.

I thought you guys were joking with this phone book thing, but it really does work! However, I noticed that in a humid environment (Delaware in the summer), the moisture permeates the pages and muddies up the bass a little. Also the mids and highs get a little muffled. I suggest keeping the book in the fridge, (or one of those vacuum-sucky bags if you have one) until you need it. In an emergency, you can hold your nose and blow to pop your ears (like in an airplane). That seems to temporarily offset the moisture effect. Thanks for a great tip!

To reduce the lateral heat shimmering dissipation effect on front-to-back imaging with my Plinius SA-250 amp, I've been using four 1998 Northern Virginia yellow pages books around the unit. This baby must generate some 600 watts when powering my Wilson Audio X-1 setup. There's so much heat turbulence induced air currents, it warps the whole sound field. Imaging really suffers. Now, the yellow pages really dampens the air flow and stray atmospheric vibrations. Unfortunately, they also catch fire when the amp is left on in Class-A mode. So, I soaked the (replacement) books in a mixture of 50% antifreeze and 50% asbestos-doped water for 24 hours, let them drip dry, then placed them back around the amp. Works perfectly! Much better than using four Shun Mook slabs since I can bend the yellow pages for optimum effect (I cracked one Shun Mook trying to bend it the first time).
Five for the sound, less one for the occasional fire risk.

Two quick mods for Joao's problem with the entry-level phone book:1. Add a Radio Shack catalog on top of your phone book. As with so many other Radio Shack items, the catalog can impart quite a bit of value for the dollar.
2. Remove the booklet from your cd/dvd case and place it between your equipment and the phone book. This will provide a filtering/conditioning effect that will smooth things out nicely. This is especially effective when playing records because of the large surface area of the album cover. However, NEVER, NEVER, NEVER, use a jewel case or a shrink-wrapped album cover, unless you want a sound so bright it will make your cat's ears bleed (hmmm, on second thought...)