Built in Shelf for Classic 2 SE

Built in Shelf for Classic 2 SE

Postby Mike O » Fri Oct 05, 2018 5:37 pm

I am building a built in shelf for my new Classic 2 SE. Picture a standard built in bookshelf. My question is, how high should the shelf be, top to bottom, to comfortably allow for removal of a dust cover I've yet to purchase. I've seen pictures of dust covers that rest on the shelf, and some that rest on the turntable. Is either preferable to or more common than the other. I'd need to allow enough height for the larger of the two, unless the types that rest on the shelf are uncommon. Thanks for your guidance.

Mike
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Re: Built in Shelf for Classic 2 SE

Postby Orchids1 » Sat Oct 06, 2018 10:46 am

Mike, I think you should first reconsider whether you need a dust cover. Most high-end tables don’t come with one. (VPI doesn’t use them on the tables on display at its assembly facility.) The only part of a table, aside from the cartridge, which should be regularly cleaned in all events, that needs to be protected from dust is the platter, so that it doesn’t transfer dust to a record. I use an iridescent yellow DJ record, which looks similar to the ones used on the VPI tables in the Products section of its website. Unless your table is in a high dust environment, the rest of your table only needs to be dusted for aesthetic reasons from time to time, which can be easily accomplished with the careful use of compressed air (Stay away from the cartridge.) and a soft brush, such as a makeup brush.

Of course, if your table is at risk from pets or small children, a dust cover is probably a good precaution. Rich
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Re: Built in Shelf for Classic 2 SE

Postby Peer Gynt » Sat Oct 06, 2018 12:37 pm

I like a cover myself.

It isn’t for dust.

It’s for stylus protection, and a good one makes the assembly look more finished.

As I understand it, the 40th Anniversary table will come with one.

Dust covers are a pain to ship, so that’s one incentive to forget about them.

Dust covers should be removed for play, so that’s another incentive to forget about them.

But IMHO, the advantages outweigh the disadvantages.

Regarding the OP’s question, my preference would be to NOT have a shelf above the TT.

I would also recommend against putting the TT on a set of shelves. The modern VPI tables need a REALLY solid mounting location. A dedicated perfectly level, rigid support at ~2’ below eye level is great.

But, if you must put a shelf above the TT, 20” should be enough unless you have a really tall dust cover, or a really tall tonearm.
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Re: Built in Shelf for Classic 2 SE

Postby Orchids1 » Sat Oct 06, 2018 1:36 pm

Depending on the position of the tonearm in relation to the open front of the shelf (tonearm facing perpendicularly to the front, running parallel to the front, etc.), you should have more space between the top of the plinth and the bottom of the shelf above the table than what is necessary to install and remove the dust cover. You will want to easily reach inside between the table and the shelf above it to make adjustments to the tonearm, such as adjustments to the counterweight, azimuth, VTA, etc. My turntable and electronics are in a custom-built, in-wall cabinet, which poses the same space issues as a table with a shelf above it. I have at least 3’ between the top of the plinth and the top of the cabinet so that I can reach inside to make these sorts of adjustments without disrupting the tonearm. Rich
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Re: Built in Shelf for Classic 2 SE

Postby Golear » Sat Oct 06, 2018 3:38 pm

Let the height of the turntable and centerweight be "x".
Let the height of the dustcover be "y". The exact height will depend on the specific model.
Let the clearance be "z". This can be whatever you're comfortable with. I'd give it 2 inches.

The height of the space should be x + y + z inches.

You can then hold the dustcover against the upper shelf surface, slide it in and then lower it. As long as the top of the dustcover is held firmly against the top of the shelf when being put into place and being removed, the bottom edge will clear the turntable and arm.

But the space, covered in 5 sides, will resonate. Even if the shelves are super-duper stiff, the volume of air itself will act like a spring, and springs have a resonant frequency. You can measure the volume and calculate the exact frequency. This equation is used in designing speaker enclosures. The bigger the volume, the lower the resonant frequency. So if you have to do it, then make it as big as possible. That's what is happening when you put the turntable in "free space" - the volume of air is as big as the room itself.

Come to think of it, before going too far with this, you could make a 5 sided box at the appropriate size, and check if the resonance is audible.
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Re: Built in Shelf for Classic 2 SE

Postby Mike O » Sat Oct 06, 2018 4:01 pm

Orchids 1 and Peer Gynt, I will be building built-in custom shelves for all my equipment that will be suitably solid with anti-vibration and isolation features. I've been thinking after reading your replies, Ill start without a dust cover, and see how that works out. I am concerned I'll be tired one evening, and accidentally bump the tonearm with it. No kids or pets in the home to worry about. I can manage about two feet high for this top shelf without pushing the flat screen tv, which will be hanging on the wall above so high it will give me a crook in my neck when watching. Peer Gynt, since it is a built-in there has to be top to the top shelf the turntable is sitting on. Above that there's nothing but wall. I think you all have helped figure this out and possibly save me the $300+ for a dust cover.

Golear, I'll take your advice and do those measurements in case I find a need to add a dust cover later on. Thanks for the advice on the resonance of the space. I've been trying to work out vibration and resonance issues before building with the help of some folks at the Audiogon site. Check it out if you've a minute: https://forum.audiogon.com/discussions/ ... e-shelving

Thanks all,

Mike
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Re: Built in Shelf for Classic 2 SE

Postby Golear » Sat Oct 06, 2018 10:43 pm

About the discussion on Audiogon...

From my experience, marble and granite have a pronounced resonance in the midrange. This can add "clarity" to some systems but not my first choice. My experience with sorbothane is also negative - it seemed to remove all the life out of the playback. The best material I've used for shelves is cheap plywood (stronger than MDF) and maple (John Boos butcher block). Of course, these are just my observations, and they may work very well for you.

You might want to look into fitting a close fitting door(s) to the shelves. The doors will take care of the dust and protect your gear. If the doors fit very tightly, then very little of the sound enters the cavity so then you won't have resonance issues. Magnets - like on a fridge door? May be. I've not tried it.

Just had a thought: there'd need to be clearance to easily put on/take off an LP, and operate the arm. This might need to be quite generous - much more than x + y + z. The opening might need to be in the region of.... 3 feet?

This is an interesting project. Hope you'll keep us posted on what you do.
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Re: Built in Shelf for Classic 2 SE

Postby Peer Gynt » Sun Oct 07, 2018 8:50 am

The transmission loss of tight fitting doors will not keep sound out. The transmission loss is mass controlled at low frequencies and damping controlled at high frequencies. The constraints of the cabinet joinings, which are somewhere between hinge and cantilever, will come into play too.

The cavity will be excited at some frequencies more than others. If you don’t believe this, put your iPhone on record, lay it in your best cabinet in the room where you listen, play music at your normal level, and listen to the recording.

Build it and see what you think.

It may turn out really nice.
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Re: Built in Shelf for Classic 2 SE

Postby Golear » Sun Oct 07, 2018 1:56 pm

Nice idea to use an iPhone! I hadn't thought of that. And one can compare the recorded sound to a "ref" sound (a recording on the iPhone, made at the listening position) to know how much resonance is from the cabinet. One can use actual music and one's ears, instead of test tones and graphs.

In the end, we might be in danger of over-thinking this. One theory may predict that it won't work but there may be other phenomena that overrides the phenomenon described by that theory. It would be good to do some experiments before spending thousands, or making irreversible changes, though.
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Re: Built in Shelf for Classic 2 SE

Postby Mr_Putty » Sun Oct 07, 2018 4:20 pm

Mike,
Are you a woodworker and doing the work yourself? If so you can modify your plans as you build. That option is a good thing. I think I would build the TT shelf containment area as a separate module. That will allow you to make changes more easily later if you so desire, not disrupting the other shelving. Reason two, you are going to have vibration from the nearby shelving adding to the TT base or surround, no matter what. You can decouple those vibes by using a floating module to your advantage. Think of a box within a box with isolation material between them. You still want mass in the TT base for stability. So I would not nix the granite or stone as a base just yet. It can be individually damped if needed. BTW, man-made countertop material (corian for example) has a higher resonance (my opinion based on tap tests and ear on the stone). I think lower resonance is better. I would nix any metal or pin based shelf supports. I suggest a stacking approach under the shelves using solid plywood, or a mix of plywood and mdf. These would be parallel to and in addition to the basic bookshelf structure. The shelves would not be attached to the side supports, as you might want to add damping of some type under them. In my experiments space is always a good thing to have. Leave yourself as much room as possible for your TT and base material. For example you might decide to try two bases at the same time, and need the extra space. There is a lot to consider and sometimes the real challenge is in going forward and working with what you have. Looking forward to what you decide and how you like the result.
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