Wall treatments “Asymmetrical”?

@newbee I found both an analog a digital slm on eBay. Is there a guide that can help me understand how to use this tool in dialing in my systems?

I’m not aware of one. It is somewhat simple though. The Stereophile test disc has a set of test tones at various frequencies. You measure these test tones at the listening position using the meter. You can start out with your system set up in a typical triangular configuration and see what your overall frequency response is then move your speakers about (or as likely your listening position!) to smooth out nulls and nodes. There is a learning curve here so don’t expect to get an instant result. It takes a lot of time and patience. Be sure to take notes - I used a graph showing test point frequencies in a form where I got a visual idea of the frequency response. BTW, although you can measure the FR at various locations in your room, for the most part the results are not useful. It is the listening position that counts. I suggest you do some basic research on the internet on using a SLM meter for audio setup - you might hit the jackpot. I don’t know that I would rely on U-tube. But once you have digested all that Toole has to say and figured out how to get started in your room using the SLM and test disc is an excellent way to fine tune your system. You are right, it IS a project! :-) Ask questions, I’ll answer if I can.

BTW there is a tutorial (so to speak) on U-Tube by Audioholic's. I didn't listen to it but you might look at it and see if will help you. I suspect there might be much more.  My Goodle search was for 'speaker setup using a sound level meter'.

@newbee just received copies of some of the suggested Stereophile cds and awaiting a Radio Shack Analog SLM, but I need to understand how the sound meter measures decibels and how that relates to setting up bass response??  The only videos that I’ve come across for use of the slm, shows people measuring how loud their exhaust system is on their vehicles. 
the only thing I can imagine is that you play various tones on your system and try to get them to produce the desired decibel level?? 
am I on the right track? 
thank you  again and again 

Wrong track, I think. Firstly, did you google the Audioholics spiel on U Tube. As I said I didn't watch it at all except for perhaps the first 10 seconds, but he did start describing a use procedure which I thought might answer your preliminary questions.

Basically the Stereophile disc will have test tones (pink noise) at various frequencies, starting at 1kh and going down in 1/3d hz increments to 20hz. Once you set up your speakers and listening chair in a reasonably good sounding set up which I assume you have achieved after digesting Floyd Toole's book and working on a good set up, you place the meter at the apex of the triangle (on the back of the chair, preferable at seated ear height, will work but a tripod would work better (and the meter has a provision on its back for attaching to a tripod). As I recall you set the meter for C weighting and then commence playing the CD at normal volume. When the CD starts playing you get instructions and information about volume adjustments and some phasing information. Then there are 13 cuts of recorded music and ultimately the test tones. The purpose of using these test tones is to measure your speakers output at the listening position. The are likely to reflect the nulls and nodes in the various frequencies as heard  at your listening position. For example if your speakers sound bassy/boomy in the bass you may find that your listening position is in a bass node and compared to other adjacent frequencies is objectionable. You can alter this response by using an external crossover, or more simply moving your listening position forward or backward. You can also affect the bass response, as you probably already know, by speaker placement, as well as the higher frequencies. It's all a dance so to speak and you'll never get a perfect set up but it's better in setting up your system than just using your ear and not having a clue what is caused by your setup to sound as it does.

The meter itself is not a correction device. Just a tool. The ultimate goal would be to create a frequency response, either by speaker movement, chair movement, or an equalizer, that reflects a sound you would enjoy more. Some folks want a flat frequency response, some like one with a rising bass and a drooping highs, others would like a flat bass and rising highs. Get all of your stuff together and play with it. Take your time, this is a lengthy process but the opportunities.

Forgive me for making redundant comments, I realize that my previous post covers most of the territory and I just trying to reemphasize them.