recommendation for turntable vibration damping

Hi,

Lumber isn't cheap either. I just put in a new deck 12' X 12' and even though that's pretty small- it set me back nearly $2K. Ouch.

Yep- blockling is putting in a piece between the joists (or studs).

The only problem I see with your joist jack method is that you are at the mercy of nature, in that you will probably need to re-adjust it often because of heave and expansion/contraction. A jack like that indoors remains fairly stable; When it's exposed to temperature outdoors....

When a builder puts in a bathtub, stairwell, or anything else that requires either a cut-out in the joists and/or extra bracing, the common method is to add blocking. It may not seem like it would add a significant measure of support but it certainly does. When the joists are allowed to flex independently of each other- they do. When held to the rigidity of its neighbors (other joists)- they don't. Pretty simple.

Use whatever type of column you wish, but I would still block the joists to the hilt. If you recently added insulation, you could just make a header or horizontal beam to distribute the load of your column of choice. This could serve to replace the blocking (sorta). Make sure you toenail the beam in an X wherever it meets a joist though. I'd double up (sister) a 2X6 (at least) for your header/beam. 2X8 would be better. I'd put two columns (per beam) if doing this method.

Thanks again, V&V.
I ake your point about the joist/jack method being subject to the mercy of nature. That said, the crawlspace should be a more constant temperature than a place that receives a mix of sun and shade.

I'd think that any solution in the crawlspace would be subject to the same mercy of nature -- even the pier solution you proposed -- althoguh perhaps to a lesser degree.

I will see how feasible blocking is for me, given the work I did on the insulation.

If I read your response correctly, you think the beam idea that I've tried with adjustable jacks (2/beam) as columns is OK. I know it does not fully replace the blocking, but it sounds like it is an improvement, albeit one that may need periodic adjustment.

I added one such header/horizontal beam, and based on the location of equipment in the room and the space/pipes below, I feel like I need to add at least two shorter beams. I could not emply one to span the width of the space due to crawlspace constraints.

Since the listening area is one section of a larger room, do you think it's wise/appropriate/or unnecessary to support the rest of the room (i.e., no equipment will be located in this area)? The listening area is already divided from the rest of the room by a header.

Thank you so much! I am learning quite a bit and feel like I'm almost all the way there in terms of making an informed decision about the solution.

Considering that the work you are doing will not be "load bearing" per se- I think ALL options (suggested thusfar) are OK.

True, a crawlspace is not as extreme an environment as the open air. Your jack will prob be fine.

I think you'll be very surprised at just how effective a mere fraction of what you are proposing will be. Hard to imagine- but bracing just two or three joists alone will be a huge inprovement. Now- factor in what you are contemplating and multiply it by 200%. Your floor won't move by any measurable degree. Audio speaking of course...

Cool...that is an excellent way of thinking about it. It makes me step back and realize that this is quite an improvement, already.

I do plan to put 1 or 2 shorter (4x4x4') supports directly under the rack and other speaker.

Guess I'll focus on the space under the listening area and not worry about the adjoining space (separated by a header).

Thanks so much! I will report back with my experience.

Everyone has been very helpful; your suggestions have been taken to heart.