Introduction: This particular entry is especially significant as it documents a detailed walk-through of the very first set of home audio speakers to be built and ship from PWK Designs. On daily basis, I receive at least two or three calls from folks asking me about what it would take for them to see a PWK Designs speaker in their home theater or listening room. Well, here it is in-depth and illustrated:
Step One: As it is with any other project, it all begins with a call. This is where we discuss all the details of your listening preferences and all the conditions of your listening environment. At least six hours out of the day, I look like this:
In this instance, the client–Derrick–had already purchased a set of HT subwoofer blueprints from me and was now looking to upgrade the front stage to something of matching quality. Throughout our correspondence, we’ve established all the details such as his listening preferences, the dimensions of his listening room, location of the subwoofer, the speakers, and the listening position. With that, I was able to compile a parts list of the speaker and crossover components that, in conjunction with one of my designs, would best accommodate Derrick’s listening objectives. Once everything had been established, I put together a price quote totaling the cost of the components, the enclosures, and shipping. The numbers looked good so, once the payment was made, I went ahead and purchased everything that I’d need to get started.
Step Two: Given the advantage of having hands-on access to all the speakers used in the project, I like to perform my own T/S parameter analysis. In my experience, the actual parameters will almost always differ from the ones published in the owner’s manual and, in a critical listening application such as this, the slightest deviation can mean a world of difference.
Once a definitive set of T/S parameters is established for each speaker, the engineering process can commence. This is where I determine the optimal alignment to achieve the desired results at the listening position. Many factors such as room modes, nulls, and diffraction can make this process quite challenging. The general density of the walls, the floor, and the ceiling, in addition to the furniture layout can also play a significant role in how a speaker needs to radiate.
Step Three: Once I’ve finalized the alignment and drew up the blueprints, I move the operation over to the wood shop where I bring the model into existence. Derrick’s design calls for extremely rigid bass ports so, while the sound resonates inside them, the ports themselves do not. A typical bass port used in a home audio speaker is either a cardboard tube or a PVC / ABS plastic mold, anywhere from an eight to a quarter of an inch thick; you can cause it to resonate simply by tapping it with a pencil… These are 1″ thick, they weigh approximately six pounds a piece, and they’re built with 13 pressure-bound stacks of MDF:
To an audiophile, there’s no such thing as overkill. Besides being virtually impervious to adverse resonances, these ports are composed of the exact same material as the rest of the enclosure for a perfect tonal match. I allow each ring to bind under heavy pressure for approximately half an hour before tracing it and stacking another layer. This process can be quite time-consuming but the results are well worth the effort.
I set the ports aside for the time being and go to work on the outer frames of the two speaker enclosures. In prepping the wood for this project, I made it a point for every cut to come from the same sheet of MDF as an additional measure to further assure consistent wood density. The frames are subject to the same amount of pressure as the ports, and are left under a heating lamp for approximately half an hour on each side:
Finally, it’s time to shape the face baffles. No mistakes can be made here since the bass ports are already bound into place. Along the face, the ports flare out to nearly three times their original cross-sectional area and, on the inside, they are suspended with a quarter-inch gap between the bottom and side walls. A 1″ radius bevel is used to round over the exterior vertical edges of the enclosures (both front and back) as a way to reduce wave diffraction:
A quarter inch radius bevel is also ran along the top and bottom of each enclosure to help reduce horizontal diffraction. Once the towers are complete, they are moved out of the wood shop and into a dust-free environment (in this instance, my listening room) for final tuning and, eventually a paint job. It almost pains me to have to conceal all this woodwork behind several coats of Polyurethane.
Now it’s time to test-fit the components. Obviously it’s a little late to rectify any cut-out or inset errors at this point, but that’s what practice cuts are for; these final ones are dead-on:
And here’s another shot from an angle to better illustrate the flush mount:
Step Four: Initial impressions: Once I’ve wired up the cross-overs (2nd order 12db/octave 3Khz high-pass for the tweeters), it was time for the first listening session. Right up front, I noticed the clarity of the speakers’ on-axis response. The horizontal axis seem to be a lot more forgiving than the vertical axis–hence the 19 deg. tilt:
This, of course won’t be an issue in Derrick’s listening room as the speakers will sit at a sufficient height for the gap between the woofer and the tweeter to be level with the listeners’ ears. (For this listening session, the speakers are on-axis with my ears both vertically and horizontally.)
Overall, the speakers exhibit a very flat response down to ~50Hz and a very shallow roll-off for a surprisingly deep extension; at 30hz, they’re still audible. This, of course, will change as the speakers are raised further off the ground and moved away from the walls. With the two speakers and the listening position forming a 40 deg. angle, and with a listening distance of approximately 6 feet, the sound stage is exceptionally deep with the individual instruments easily placed even beyond the room’s physical boundaries.
Finally, the enclosures are primered, re-sanded, and several coats of polyurethane paint are applied for a glossy finish. The cross-overs are then permanently attached with large amounts of hot glue (to limit resonance) and all the components are tightly mounted onto the enclosures which are now ready for shipping:
“Let me start by saying I will forever be a PWK Designs customer. I have always had a interest in home audio since I was a teen. Before thump in the ride was the thing, it was normally a house party that got it jumping off.
I’m more layed back now but I still had a need to get a real setup. I wanted to get something that I can call my own. I wanted to go the custom route. I search and search until I found PWK Designs. Unlike other forums and websites. This guy (Pete) seemed to have more positve feedback than many. I joined his forum and got into asking audio questions pertaining to home theater and car audio as well. No matter who messaged me. Everyone said, “Pete is a speaker designing genious”. If you don’t believe me, go to the forum and read the workblogs/testimonials.
So after seeing pics of his designs and work displayed on youtube I was sold. Upon getting a case number for the design and build, Pete wanted to know details about what I want in terms of tonality, genre of music, & dimensions of the area (livingroom) the system will be playing. First, was a suggestion of a pair of towers but due to some space restraints, I wanted to go with something smaller. At the same time, I’m looking for big home theater front stage sound. Thus came the idea of a pair of mini-towers. I wanted some speakers that could set on the top of stand (72″L x 22″W x 26″H) next to my Samsung DLP. Pete said, “it would be a challenge but I can pull it off”. Little did I know that was an understatement.
I was confident enough in Pete to let him select the parts for this project. The list as goes as follows: (2) Alesis 6.5″ shielded carbon fiber cone woofers, (2) Vifa D19TD-05 3/4″ dome tweeters, (2) Crossovers 2-way 8ohm 3,000hz 100w, and (2) pairs of Dayton BPA-38G binding post. The source I currently have is the Pioneer Elite VSX-TX24 THX certified (90×5 watt) digital receiver.
Periodically Pete emailed me with updates of progress to show me the details and engineering going into my design. I was like a kid again all excited. When they were finished I eagerly counted down the days while they were in shipment on route to my home. When they arrived (after four days) I ripped into the box and began hooking them up to my receiver.
In my first listening session, I did nothing but play r&b. The Mary J Blidge was very smooth and detailed but somthing was lacking. The pioneer receiver was struggling to get the towers to live up to there potential. At first I thought I would be just fine with the pioneer elite despite Pete telling me to invest into a separate source. Man was I wrong. I was explaining to him how I had the bass/treblegain all the way up and I just knew the speakers wanted much more. The alesis were hardly flexing at all with the volume up high. So I called and talked to Pete about what amplifier would be best for my application.
He recommended the Dayton APA150 and after reading all the customer reviews on Parts Express I got me one. It took less than three days to arrive so here’s the moment of truth. I connect the rca’s from the separate amp output located on the back of the pioneer receiver to the input jacks on the dayton amp. Then I ran the speaker wire from the speaker to there respective terminals on the back of the dayton amp and powered it up. I played Mary J. Blidge again to get a real feeling of the before and after effect.
With the volume turned up a quarter, the sound was astounding. I was hypnotized. I’m talking completely hammered on how great the sound drastically improved. I’ve read and seen videos of audioholics that say, “when you hear music in its true form, you drift into another world.” Well, I can vouch for that. I was listening to my new setup for about six hours non-stop. Just playing one cd after the next. Pete told me that when he tested the speakers himself the mini-towers had a 50hz curve response with a 30hz roll-off. After getting the amp I needed to bring these speakers to life, he was not kidding around. This is by far the best front stage I’ve ever owned. I’m not an expert but I have sat in many listening rooms and theater rooms. This guy makes speakers that should cost around $3k a pair. You know you are lost for words when all you can say is WOW!!!!!!!
Rich deep tones with authority and smooth crisp accurate highs will make you swear you are there in person. That is the best way I can describe the performance of these mini-towers.
Because of Pete, I’ve got bitten by the audio bug. I am already making arrangements to upgrade to a 5.1setup. All being designed and built by Pete. I’ve only had this new setup for a week. I love my new front stage.