Troels and DIY Loudspeakers

This post briefly covers 3 topics: a) what kind of center channel speaker I wanted, b) why I decided on a do-it-yourself loudspeaker, and c) Troels Gravesen’s website.

A center channel speaker could be a standard vertically oriented two-way (woofer /tweeter, one atop the other) speaker.  More commonly, a center channel is a horizontally oriented speaker with a central tweeter flanked by two woofers.  Less commonly are 3-way W-MT-W designs where a tweeter/midrange in the middle is vertically oriented with woofers on the left/right sides.

2-way loudspeakers are the best bang for the buck – your investment goes to one woofer and one tweeter, and a simpler crossover network (circuit to divide the signal between the woofer and tweeter).  Most 2- ways are meant to be oriented vertically and have good horizontal (side to side) dispersion, meaning the sound stays about the same as you move from side to side (but not as much up and down).  Some designs also have good vertical (up/down) dispersion meaning they would also work well on their sides.

I wanted a high quality center channel to match my Spendor SP 2/3 speakers, and got interested in DIY because I thought it would be a fun project and I hoped it would be competitive in sound quality with much more expensive speakers.  Even though DIY for me means paying retail prices for parts, and manufacturers buy parts at wholesale, a DIY speaker may use parts of a quality that are unlikely to be found in commercial speakers of reasonable price.  For example, the speaker I selected uses top quality Seas Excel drivers, as well as Jantzen Audio capacitors and inductors.  A pair of monitor 2-way speakers with such drivers and electronic parts may have a retail price of $4,000 or more, and many such designs are not sold as single speakers.

Troels Gravesen ( has an amazing website full of inspiring projects, photographs, and a wealth of insights and observations from years of projects and experiments.  I selected his CNO-T25 design partly because of its relative simplicity (a rectangular box, 2-way design), and the excellent measured horizontal and vertical dispersion, making this design likely to sound good even if the speaker is placed on its side or if one listens from a standing position walking around the room.

Geometry and Stereo

In the previous post I explained that the best place to listen to music in my house is in the kitchen.  When I’m in the kitchen, I’m not sitting in some idealized perfect audio sweet spot, I’m moving around.  And, I’m often about 16 feet away from loudspeakers which are 7 feet apart.  The geometry of my listening position relative to the loudspeakers has a lot of implications.

When I got my first stereo system, I was impressed with the imaging – the ability of the two speakers (with a proper recording) to create a visual image where I could “see” the location in space of various instruments or voices.  And when I’m watching a movie, the sense of the location of the sound should match the action on the screen.  But when I’m in my kitchen, it is a different perspective.

Because the speakers are relatively close together compared to how far away I am in the kitchen, most sounds appear to be coming approximately from the center.  And that’s closer to what I usually experience in a live concert in many cases.  Usually I’m relatively far from the stage, and the main interest – perhaps a violinist, or a solo singer, or a piano, is usually near the center of the stage.  And, as discussed in previous posts, most recorded music these days may be available in a 2 channel format, but it’s not a real stereo recording.

So I began to think about adding a center channel speaker, and wondered what would happen.  I bought a fairly high end surround sound processor and used it to create a center channel signal using Dolby Prologic II (or a variation).  At first, I used one of my Spendor Sp2/3 speakers, positioned horizontally, as the center channel, with a pair of inexpensive small bookshelf speakers.  I found a few things; remember these observations are strongly related to the geometry of my listening room and may not apply in other situations:

a) I liked having the physical center channel speaker – the sound coming from the real center was clearer/sharper than the phantom center I was getting from just two speakers.

b) The overall sound coming from a superior center channel speaker with modest left/right speakers was very good – the left/right speakers were important in making the sound more spatious, but as most music has the most important element (solo voice, or solo instrument) mixed to come from the center, it was the center channel that was the most influential determinant of the sound.  In fact, sometimes I would listen to just the center channel speaker, and because of my distance from the center speaker, and perhaps also because of the sound reflections in the large room, just the single speaker alone sounded pretty good, although I preferred the sound of all 3 front speakers.

c) I got a good result with non-matching center and left/right speakers.  Now for movies you want a close match between front speakers, but for music alone the left/right positions of instruments/voices are often fixed for a given music track, and listening as I do from 16 feet away I got an overall blend that didn’t depend on the center exactly matching the left/right speakers.

The experiment with the Spendor (lying on its side, clearly not optimal) as a center channel, lead me to want to find a center channel speaker so that I could use the Spendors as left/right speakers.

Sight and Sound in a Kitchen

This is an audio blog, so a post about kitchen design might seem off-topic.  It turns out that for me the best place to listen to music in my house is in the kitchen.  And I have read a lot of books about kitchen design, and I can’t recall anyone mentioning the importance of good audio in the kitchen.  Yes, a kitchen can sometimes be a noisy place, but it can also be a fairly quiet place, and if you spend a lot of time in the kitchen, why not be able to listen to your favorite music through a high fidelity audio system?

I’m not Jacques Pepin, but I like to cook.  And I like to read about kitchens and kitchen design, some interesting things to read are Johnny Grey (, Bulthaup (, Mick de Giulio (, and the Not So Big House (

So a little digression here about some firmly held beliefs.  You may think that what matters in a kitchen is the work triangle, or a fancy cooktop, maybe granite countertops?  I have a different point of view, what matters to me is:

a) how is the kitchen connected to the rest of the house?  This question is why I think a lot of people don’t get it – hence all the “kitchen design” stores focusing on the door style of the cabinets and other superficial characteristics, but with no thought about the interior architecture and how the kitchen space relates to other spaces in the house.  By the way, our wonderful great room/kitchen space was designed by Heidi Richardson AIA (  The lead architect, who came up with the design for many of the details including the fireplace, was Adam Barton (

From living in previous houses, we found that guests all crowded into the kitchen, and so having an isolated kitchen space isn’t for us.  Also, we inverted the common convention of the kitchen adjacent to or part of an informal “family room” and with a separate “formal” living space.  For us, a better solution is to have the kitchen be part of the less frequently used “entertaining” living space which does NOT have a tv, and the family room (termed away room by Susanka) with say tv is in a separate (perhaps nearby) space.

b) what are the sights and sounds in the kitchen.  I like to look out through the living space into the outdoors, and I love to listen to music while I prep and clean up.  In fact, listening to music is the major motivation for me to be in the kitchen cleaning up on weekend mornings.

c) lots of counterspace.

d) ventilation.

e) orientation – is your back to the room most of the time, or are you looking into the space?  Our kitchen has a big multi-level island with a large prep/cleanup sink, dishwasher, and the back wall of the room has the actual hot cooking equipment, ventilation, and a secondary sink.  This, to me, is the perfect arrangement.  Many kitchens have the arrangement backwards, with the island having the cooktop and a suspended vent hood (which doesn’t work as well as the vent hood against the wall), and the prep/cleanup and so on is behind.  Working in such a kitchen means that most of the cooking time is spent facing a wall with one’s back to the open room.  Glossy magazine ads for such island kitchens often show a cook smiling while stirring a pot, talking to friends standing or seated nearby the island.  The reality in our kitchen is that time at the stove is relatively short, and stirring the pot isn’t a constant activity, but washing, cleaning, prepping, those activities take a lot of time and are much better spent with a nice view and beautiful music.

Here’s the view from the main sink in my kitchen, looking out into the room.  Notice there is lots of light, and of course the audio system.

To give a perspective, the room is a cathedral space about 17 feet high in the center, 10 feet high at the side walls, 32 feet long, and 18 feet wide in the main portion.  More about the space in the next post.