Sunday, October 26, 2014

Focal Profile 918 Set up (probably 908 too)

This is a guide to placing Focal Profile's in the optimum location.  If you are intereted in upgrading your Focal Profile 918's to 2016 levels of performance please visit the Focal Profile 918 Ultimate Upgrade Guide page.

So I here are my secrets to getting incredible sound from the 918s that you have today.

In addition to tonal balance the thing most never have right is the imaging.  These are great speakers for imaging, thought it tends to be on a single plane, from left to right and front to back they throw a wide and deep sound stage and disappear.  The 918s are also very room friendly and have a really sweet tweeter.


Items you will need:
Attach outriggers before proceeding.

Tweeter Taming

One of the best, and least expensive, tweaks for the profiles is to line the grill with felt to either side of the tweeter.  This is huge.  It smooths out the treble while deepening the sound stage.  Take your felt sheet (available from any craft or art supply store for about $0.50)  cut a strip about the width of the top portion of the grill, that acts as wings to the tweeter.   You will need two sections per speaker, one for either side of the tweeter.  Fold in half and make the oval V cut out for the tweeter mounting.  You will probably want to leave about 1/2" of space.  Stuff behind the grill cloth.   You do not need to use felt with adhesive.  In fact it's neigh impossible to stuff that back there.  Done correctly this ends up being invisible.

The Sweet Spot

Your seating position should be in between the speakers but no closer  than to form an equilateral triangle between the seat and speakers.  I find that further away works as well if not better.  If you are closer than that I would suggest moving the speakers closer together or moving the seat further away.

Set up the speakers at least 20" from the sidewalls and rear walls.   They do need some rear wall reinforcement.  Point the speaker's straight ahead, leave the lower grill cloth on, remove tweeter covers.   Focal, Stereophile and my own experience proves this is the way to go.  This is one thing most get wrong.  The grill cloths are essential for imaging.   Starting this exercise otherwise leads to madness.

Bass/Midrange Balance

Adjust distance from rear of speaker to wall until bass/midrange balance at your seat is good.  If bass is boomy move away from wall.  If weak, move towards the wall.  Measure distance from rear of speaker to wall, make sure both speakers are same distance.

Turn all outrigger knobs counter clock-wise to get speakers as low as possible.  Level speakers front/back, side to side and angle straight ahead.   With the outrigger feet this takes 10 minutes.  Hours otherwise.


Toe-in is the amount we will turn the speakers towards the listener.   Proper toe-in affects imaging and treble balance. 

The Goal

The goal is to find the speaker angle which provides you with great imaging.  To me this means the following:  
  • Instruments and performers are evenly filled in from left to right.
  • The speakers no longer appear to be the source of the sounds
  • The imaging in the center is as strong as between the center and either speaker without gaps. 
  • Music may appear to be coming from wider than the speaker placement. 
The one place where the 918s suffer in terms of imaging is height.  They tend to image in an area like a strike zone, centered between the midrange and tweeter.  


Measure the distance from the side wall to the center of each tweeter housing.  Using a tape measure and level, on the opposite wall place masking tape horizontally from that distance to about a foot and a half in on both sides of the wall.     Mark every two inches inwards for about a foot.

Turn on laser level.   Place on top of speaker so line is vertical.  The line should cut tip of tweeter casing and center of "C" in the word "FOCAL." on top.  Now turn speaker on a rear foot (you did get the outrigger feet, right?) until the laser cuts outermost pencil mark on the masking tape on the oppositve wall.  Repeat both sides.  If you've done everything right, you should be able to put the laser level on one speaker, facing the opposite speaker  so the line is vertical and slice between the grill and speaker on both speakers simultaneously.   Adjust if not true.   Now your speakers are perfectly square to the room.

Setting Expectations

Sit in the expected/desired sweet, then try moving forwards or backwards 2-4" a a time until find a magic distance where it all locks in.  Think of that as the situation we wish to mimic when you have the toe-in correct.  It just may be you found the right place on the first try, but it's unlikely.

Now, put your chair back in your preferred location.

The image may be completely separate or have a left, center and right with holes in between.  

The moments of truth

For the remainder of this exercise, you will use the outriggers to keep the speakers from moving excessively by keeping the outermost, rear foot of each speaker in place.  When turning the speaker you will tilt the top towards that foot until the remaining 3 feet have just lifted, then turn as needed.

Toe in both speakers so that the laser progresses inwards a single mark.   A little after the best angle the image will collapse and speakers will become the main apparent sound sources.

If you have toed in these speakers so the tweeter is pointed at your ears it's too much and you'll get excessive and tiring treble.

Check both speakers again for level, and verify image is still good.   Again, outriggers are the way to go.  Will also reduce chances of speakers falling on floor.

Now, using a similar method as above, tilt speakers up and down to taste and seating position as you feel appropriate, taking care to keep the speaker level from left to right after each adjustment.  Use laser as guide, but this time horizontally to ensure both speakers are tilted equally.  In this case you do want the plane of the tweeter to be around the plane of your ears.  Remember there's about 3-4" between tweeter and laser level, so if you use marks, say on a board on your chair, or tape on your recliner, adjust accordingly.

Personally I like my ears to be a little below the tweeters.   Your mileage may vary.

Recommended Cables

I use Wireworld Equinox speaker cables with bananas on speaker end.  I know this sounds like Voodoo, but I had friends who loved jazz and know nothing about equipment.  Without telling them which was which they could reliably tell the Wireworld was the superior cable for imaging.  However we disagreed on the merits of the tonal balance, and they preferred 12 guage Mogami Sound Runner I had bought 20 years ago.

Thursday, October 16, 2014

Quick Pono Review

This past week I had the chance to listen to the Pono music player at dreamforce.  I happened to have a classic iPod with me with ALAC files of a couple of songs that were in the demo units.   I also had Shure in-ear-monitors I bought a few years ago with me.

The quick review:  The music player sounds really solid, BUT... it was clear to me that we are listening to modern remasters.  Doing direct comparisons is really impossible.  That being said, I mostly really liked the remastering and the overall combination of player + new masters I was listening to with the exception of Miles Davis Kind of Blue.  Great noise and clarity but the stereo field seemed exaggerated.

Full disclaimer:  I only listened for a few minutes, and there was this model-gorgeous blonde listening to music across the table from me, so I may have been distracted.

Wednesday, January 8, 2014

Add HEPA filtration to any CPAP for $20

In a previous post I had written about my attempts to modify the Resmed S8 to add HEPA filtration.  The purpose was to help my allergies and asthma, and maybe by reducing my allergen load I might even improve the quality of rest I get when I sleep.   I've also written how dissapointed I've been in that Resmed and other's don't offer this as a standard feature, and that the filters they DO offer are so chintzy.  Those little inserts are designed to protect the CPAP, not you.

In the past I had thought of elaborate schemes to do this, going so far as to order industrial HEPA medium (i.e. filter) for the woodworking industry, cutting it to fit, I've thought about making special molds or filter holders to fit the wonky air entrance of the S8, making a custom CPAP filter box, you name it.  All those solutions were expensive, time consuming and most looked ugly.   I have finally found a good compromise which is ridiculously easy to make, very inexpensive and at least after my first night, worked flawlessly.

You'll see a picture of my prototype below.

You will need the following supplies:
  • A CPAP machine, such as the S8, but almost any will do. 
  • Wide tape, such as packing, duct or Gorilla.  
  • Kenmore Q Vacbag Style Q
  • Scissors
The idea is simple.  The Kenmore Q bags filter down to the same size of particles as HEPA requires.  This is very good for anything short of laboratory grade clean room filtration. 


Because some packing tape can off-gas it's a good idea to do this several hours before you go to sleep. 
  1. Cut the bag open at one side or the back.  Just enough to allow you to slip your existing CPAP machine into the bag. 
  2. Detach the hose and thread it through the intake of the bag.  Then attach it to y our CPAP.  
  3. Remove any existing air intake filters.   
  4. Put CPAP in bag, pulling out as much of the air hose as needed to snugly fit the bag's opening up to the CPAP itself. 
  5. Make sure the power cord is attached.  It's probably easiest to move it to one side or the other of the slot you cut. 
  6. Close the slot you cut out with the tape.  Try to get as air-tight a fit as you can. 
  7. Check that the CPAP air intake is not pressed up to the media.  You want to have that be loose fitting, with room so that as much of the bag's surface area is used as possible.   
  8. Optionally, tape the hole around the hose itself, where the bag's cardboard insert is closed.  
For best results, keep the bag as loose as possible so there are as many paths of air available.

Congratulations, you now have a very efficient,  and inexpensive, HEPA filtration system attached to your CPAP machine.  May you have many allergen free nights of rest. 


In terms of efficiency, etc. the bag is incredibly well suited to this task.  Though the filter is of a much tighter weave than the OEM part we compensate for this by having about 100x or more surface area.

You should notice is that the bag does not crumple when you turn the CPAP on.  In fact, the bag doesn't do anything.  This is a VERY good sign that the bag is barely in the way of the airflow.   Imagine for instance if the bag were a trash bag instead.  Because the bag has no air flow, as soon as you turn the CPAP on the bag would collapse, like a vacuum seal food infomercial.   The same is true by the way in the woodworking / industrial application of the media.  If the media inflates very firmly it means it's clogged up and restricting airflow.

Isn't this like perpetual motion? 

No, not really.  We are taking advantage of the fact that while the bag is good for a vacuum cleaner it is overkill for our needs.  Think about how much air a vacuum has to suck per second, versus how much air you can intake in a second.  No comparison.  The bag is designed for much higher air flow than the CPAP could possibly need but has much better filtration than CPAP vendors offer.   The vacuum bag will not only will keep dust, dust mites, molds, etc. from the air you breathe, but will reduce the power consumed by the CPAP and ensure that enough air flows around the unit naturally to keep the machine at normal operating temperatures.  All in all, a win win for you, the CPAP and the environment. :) 

Is this worth doing?

Maybe.  We do know that allergies, like colds, activate our auto-immune system which takes energy and stresses our bodies so the idea that reducing allergic response could lead to more energy and less stress is completely medically and scientifically sound.   I also believe that the bags filter many more allergens from the air than the S8 foamy filters can.  However, whether adding a HEPA bag to your CPAP will make a difference to your situation may require experimentation but at $20 per experiment I think it's worth trying.  

Here's my suggestion, if you know you suffer from allergies, and you are condemned to a life of sleeping with CPAP, try it for a week.  See how you feel and how alert it makes you.  Blog your experience either way.