DIY Room tunes: close enough for rock and roll?

I am going to start working on building some home-made bass traps and room lens from some info gathered from the net and from a fellow Audiogoner.

My question here is, how close can my DIY project come to the real thing in terms of functionality? Can I get as close as 90%?
You can get to 99.99% if you take the time and effort. There's nothing magical about either type of device, it's just paying attention to detail and careful placement and listening.

I do question whether you should mix both bass traps and room lens in the same room. Argent recommends against it, but maybe others have direct experience.

Good luck.
Onhwy is correct, on both accounts. Argent does not recommend this mix as they want the upper bass and mid band to be pure and not muddied by Bass traps. The purity gives the resonator the ability to function on high Q signals. The bass traps will lower the Q and render the lens less effective. This is not to say that using both won't work, it's a matter of how dramatic the effect of the lens would be--much more so without traps.

First things first--what is the biggest problem in the room? Is it the bass--if so tackle that first. Do you think the traps will accomplish the job--if so--how? Is it mild taming you need, or do you have a high Q peak at 80Hz (or some other specific frequency). Where I'm really going with this is--don't do it because it worked for someone else. Figure out the weakest link and go after it first, then do the next thing (which will become apparent once you fix the fist thing--if it isn't apparent already).

Bass traps are often misunderstood and there are several types. Each type has different uses, placement, and Q factors. If you need type "A" and build type "B", it won't work (or not very well) and you will wonder--why didn't that work for me when it worked so well for my friend.

The lens definitely has it's purpose and it is a low efficiecny radiator in the upper bass-mid band. I don't know much about your room, but it is unlikely this is a good starting point. Rather deal with the fundamentals first: frequency response and reverberation times. Then move on to enhancements such as the lens. Quite honestly I wouldn't use the lens in a well designed room, but it's not really designed for that anyway.

I hope that's been some help and perhaps saved a bit of effort--take it one step at a time if you go the DIY route. I also recommend that you measure the room. It will save you a lot of time than trying to do things stirctly by ear. And please visit our listening room, which is a basic tutorial on room anomolies.
go to audio asylum and do a search on jon risch. he is the resident DIY guru for room treatments