This last weekend had cause for celebration: the loudspeakers are finished*!
It was a triumphant moment to sit back with a beer and just listen for a few hours. This is the moment of payoff, with sweet sounds being the spoils of victory.
As with so many long projects, I found myself rushing down the home stretch. I did have one moment that sort of cut through the frenzy; when I turned the soldering iron off and realized, “Huh. Well, that’s it, there’s no more soldering to be done.” For a brief moment it actually bummed me out, that the section of the program flush with the thrill of ongoing creation was about to conclude. As quickly as it came, it left, as I reminded myself that the rest of the night would be devoted to listening. Ahh, tis a blissful thing, high fidelity.
A large part of the joy in building loudspeakers is listening to familiar recordings on them, and finding things to hear that you never heard before. Inevitably, a given pair of speakers will reveal something new to you, no matter how authoritative your reference set in the living room or the richness of your open-back headphones.
Firing up the album “Arboreal” by The Flashbulb brought forth a whole slew of details that I had never heard before. Notably, I learned that there is a low-res filter over a lot of the synths in “A Million Dotted Lines”. Never caught that. Miles Davis’ “In A Silent Way” also makes for excellent auditioning. “Fahrenheit Fair Enough” by Telefon Tel Aviv blew me away with the lush Rhodes intro, and the outrageous density of electronic sounds and tweaks as the beat drops. That track is like pop rocks+coca-cola for your ears.
The Scan Speak tweeters are crisp. They’re quite ‘forward’ for a fabric dome but I don’t think “bright” accurately captures their timbre. I think “articulate” would be the best word to describe the sound. Definitely a good bang for the buck, no doubt. Would I get them again? Yes, if I wasn’t so curious to try other brands and types of tweeters. I’m all but certain that my next speaker design is going to have a ribbon tweeter. I’ve always been curious about those.
I’m definitely glad that I included an L-pad in the design (a volume control for just the tweeter, which is a first for me). When the L-pad is set to max, the speakers sound topheavy. Those tweets are rated at 91.4dB with a 6 ohm impedance, while the woofer is specified as 91dB at 8 ohms. It may be that the lower impedance causes the tweet to draw more power, in spite of the nearly identical efficency rating… although those impedance ratings somewhat come down to semantics. Something I still need to do is measure the overall frequency response of the system. That will be illuminating. But with the L-pad at max, the speakers sound bright, the same way that “flat” response studio monitors commonly sound bright. So these babies should work good for mastering duty. And when you just want to listen, you can dial back the treble for a more balanced sound.
When I sat down to listen to these guys, I really wasn’t sure what the ideal setting for the L-pad should be. One surprising detail I figured out is that it really depends on what you’re listening to. To broadly generalize, I liked them “hotter” for electronic music, with the pads at -2/3dB. For jazz and folk music, they sounded best at about -4/5dB. And for rock music, I liked them dialed back to maybe -7dB. It’s pretty cool being able to control the sound quality by adjusting the tweeter output. Next time I build a new set of speakers, I will definitely include L-pads again. It’s almost like getting to have many different pairs of speakers all inside one box.
There remains a few things which must be done before these guys are completely “done” and ready for duty. Number one on that list is that I need to replace one of the binding posts: I was using a ratchet to fasten down the bolt/washer on the inside and holding the outside terminal steady by means of a drill bit inserted into the cable opening when SNAP! the post broke in half! Apparently I don’t know my own strength? For a brief moment I was very distraught that I wouldn’t be able to listen to them for another week! Then I realized I could just solder the connecting wire onto the broken terminal. A ghetto patch, but it’ll work until I can get new terminals in the mail.
I also didn’t bond the flared port tubes with ABS cement yet. Part of me wonders if they are really the correct length. I used the formula that came with the flared tubes to determine the port length, which is a very short 5″. That only left about a 1″ section to be straight, while most of the port length is taken up by the flares. I did calculate that airspeed through the port and it was low enough that I really didn’t need to use flared ports, but I think they look cooler, and they didn’t add that much extra cost (yay sales!), so why not.
I may or may not need to change a few things after I plot the frequency response too. More or less foam inside, inverting the polarity on the tweet, etc. Before I put the foam on the inside of the enclosures, these things were BOOMY. It kind of scared me. Thankfully adding foam made a big difference.
So yeah! They’re finished! If you ignore the fine print anyway. Some tweaking will be going on over the next couple weeks. Expect to hear more!