I'm at a point in a project where I seem to have blundered into an incredible sound -- and I'm eager to learn why, and whether these project speakers could be made to sound even better.
I originally posted details in the "Multi-Way" forum, but as I've learned more (I'm a novice) I started to realize these speakers are really full-range, with a first-order, high-pass filter comprised of a single capacitor feeding a "super-tweeter" (if a $6 part can be called "super" -- heh).
(As background, here's the original thread, in Multi-Way:
http://www.diyaudio.com/forums/multi-way/197731-solid-walnut-domus-resto.html )
In a nutshell, I found these solid hardwood Domus speakers for $4 at a thrift store. They are an interesting combination of super-expensive looking parts (solid hardwood cabs, and one huge, label-free, hand-made-looking capacitor!) and really cheap parts ($6 Pioneer 10mm polymer dome tweeters, commodity 1980s-era Infinity midranges).
Since hardwood is so conducive to refinishing, I decided to rebuild them. One was blown. It was miswired internally, with the tweeter exposed to a full-frequency signal, and the woofer had also perished. So, I decided to replace all four drivers. Since I don't know too much about speaker building, and Domus appears to have been a respected maker, I tried to just stick as close as possible to the original design.
As noted, the only cross-over network is a single capacitor in each. One capacitor is label-free, possibly handmade, packaged in a fairly large cardboard tube, approx 2.5" x 1". The cap in the other speaker is smaller, and had a label: Culver 4.7uf 50VNP +/- 10%.
The original Tweeters were a cheap Pioneer model, 6-ohm. I couldn't find NOS replacements, but did find some 6-ohm 10mm polymer domes that looked nearly identical, and even said in the description that they could be used with a first-order filter:
Audax TW010F1 10 mm Polymer Dome Tweeter: Madisound Speaker Store
Next, I tried in vain to find a full-range driver that would fit, physically, into the 4-3/4-inch cutouts. Okay, I did find *one*. But it was a $100 Fountek model, and that seemed like too much money for just a quick, thrift-store project. So, I opted for a Fostex Woofer that cost $30 on sale, and despite being a woofer, appears to have a pretty flat response to about 8kHz:
Fostex FW137 5.5" Woofer Shielded: Madisound Speaker Store
I also liked that the FW137 has an xmax of only 1mm. I thought that might be an advantage in these cabinets, which are quite small. I realize this may flout popular opinion on such things.
Anyway, I took the speakers apart, and used a citrus-based lacquer cutter to remove the old finish. I did a very light three-phase sanding, 120, 220, and 400 grit paper. Then I applied three coats of a General Finishes water-based varnish I had sitting around, left over from refinishing my kitchen cabinets earlier this summer. They're pretty!
I needed to replace the original cabinet damping material, which appeared to be wood-pulp based, and which had deteriorated through the years. I read about the various high-tech damping materials available. However, my experience as an outdoor enthusiast has left me skeptical of "technical" materials. I decided to try wool. Each fiber is hollow, so the surface area in a piece of wool is huge. I found a very thick (3/16") old wool scarf, cut pieces to fit, and used rubber cement to adhere it to the back, bottom, top, and sides.
I had to drill new holes for the new drivers. I used rubber cement to fill the old holes. The woofer came with a gasket. The tweeter did not, so I used rubber cement on the tweeter flange and the cabinet below, to create a tight seal.
I plugged them in, not expecting too much, and was just blown away.
I should disclose that my "main" speakers are a full-range design: Zu Tones. So I am used to the full-range "sound." But even that did not prepare me fully to be sitting here as I am right now, with the band arranged about my monitor, shoulders, and desktop.
The sound is *good*. There's rich bass. Not as loud as the similarly sized (though slightly bigger) Boston Acoustics A40s that previously sat next to my monitor. But tighter, less rumbly/vague. Easier to distinguish a bass drum and guitar.
The voicing seems neutral, very monitor-like. Not midrangy at all, unlike the way the one good Domus had sounded in its original state.
At first, I thought the treble might be a bit forward, a little crisp. However, either I'm getting used to it, or perhaps they are mellowing a little? What initially sounded a little brassy is now starting to sound like sparkle.
Anyway, at this point, I'm very pleased. I'm planning to continue by building something to replace the missing grills. I'd also like to countersink the woofers, as they're designed for this, if I can find a small router I can borrow.
My question for you is... from this description, what mistakes have I made, and what are the simplest things I could do to get even better sound? My original thought was just to get these into a working state again. Encouraged by a little success, now I'm interested in making them sound really as good as they can.
So, higher-end tweeters? New caps? Rewire using fancy oxygen-free boutique wires? (the harnesses presently are vintage 14g plastic-wrapped with spade terminals).
Or, should I declare victory, and leave well-enough alone?
Thank you,
-Henry
I originally posted details in the "Multi-Way" forum, but as I've learned more (I'm a novice) I started to realize these speakers are really full-range, with a first-order, high-pass filter comprised of a single capacitor feeding a "super-tweeter" (if a $6 part can be called "super" -- heh).
(As background, here's the original thread, in Multi-Way:
http://www.diyaudio.com/forums/multi-way/197731-solid-walnut-domus-resto.html )
In a nutshell, I found these solid hardwood Domus speakers for $4 at a thrift store. They are an interesting combination of super-expensive looking parts (solid hardwood cabs, and one huge, label-free, hand-made-looking capacitor!) and really cheap parts ($6 Pioneer 10mm polymer dome tweeters, commodity 1980s-era Infinity midranges).
Since hardwood is so conducive to refinishing, I decided to rebuild them. One was blown. It was miswired internally, with the tweeter exposed to a full-frequency signal, and the woofer had also perished. So, I decided to replace all four drivers. Since I don't know too much about speaker building, and Domus appears to have been a respected maker, I tried to just stick as close as possible to the original design.
As noted, the only cross-over network is a single capacitor in each. One capacitor is label-free, possibly handmade, packaged in a fairly large cardboard tube, approx 2.5" x 1". The cap in the other speaker is smaller, and had a label: Culver 4.7uf 50VNP +/- 10%.
The original Tweeters were a cheap Pioneer model, 6-ohm. I couldn't find NOS replacements, but did find some 6-ohm 10mm polymer domes that looked nearly identical, and even said in the description that they could be used with a first-order filter:
Audax TW010F1 10 mm Polymer Dome Tweeter: Madisound Speaker Store
Next, I tried in vain to find a full-range driver that would fit, physically, into the 4-3/4-inch cutouts. Okay, I did find *one*. But it was a $100 Fountek model, and that seemed like too much money for just a quick, thrift-store project. So, I opted for a Fostex Woofer that cost $30 on sale, and despite being a woofer, appears to have a pretty flat response to about 8kHz:
Fostex FW137 5.5" Woofer Shielded: Madisound Speaker Store
I also liked that the FW137 has an xmax of only 1mm. I thought that might be an advantage in these cabinets, which are quite small. I realize this may flout popular opinion on such things.
Anyway, I took the speakers apart, and used a citrus-based lacquer cutter to remove the old finish. I did a very light three-phase sanding, 120, 220, and 400 grit paper. Then I applied three coats of a General Finishes water-based varnish I had sitting around, left over from refinishing my kitchen cabinets earlier this summer. They're pretty!
An externally hosted image should be here but it was not working when we last tested it.
I needed to replace the original cabinet damping material, which appeared to be wood-pulp based, and which had deteriorated through the years. I read about the various high-tech damping materials available. However, my experience as an outdoor enthusiast has left me skeptical of "technical" materials. I decided to try wool. Each fiber is hollow, so the surface area in a piece of wool is huge. I found a very thick (3/16") old wool scarf, cut pieces to fit, and used rubber cement to adhere it to the back, bottom, top, and sides.
I had to drill new holes for the new drivers. I used rubber cement to fill the old holes. The woofer came with a gasket. The tweeter did not, so I used rubber cement on the tweeter flange and the cabinet below, to create a tight seal.
I plugged them in, not expecting too much, and was just blown away.
I should disclose that my "main" speakers are a full-range design: Zu Tones. So I am used to the full-range "sound." But even that did not prepare me fully to be sitting here as I am right now, with the band arranged about my monitor, shoulders, and desktop.
The sound is *good*. There's rich bass. Not as loud as the similarly sized (though slightly bigger) Boston Acoustics A40s that previously sat next to my monitor. But tighter, less rumbly/vague. Easier to distinguish a bass drum and guitar.
The voicing seems neutral, very monitor-like. Not midrangy at all, unlike the way the one good Domus had sounded in its original state.
At first, I thought the treble might be a bit forward, a little crisp. However, either I'm getting used to it, or perhaps they are mellowing a little? What initially sounded a little brassy is now starting to sound like sparkle.
Anyway, at this point, I'm very pleased. I'm planning to continue by building something to replace the missing grills. I'd also like to countersink the woofers, as they're designed for this, if I can find a small router I can borrow.
My question for you is... from this description, what mistakes have I made, and what are the simplest things I could do to get even better sound? My original thought was just to get these into a working state again. Encouraged by a little success, now I'm interested in making them sound really as good as they can.
So, higher-end tweeters? New caps? Rewire using fancy oxygen-free boutique wires? (the harnesses presently are vintage 14g plastic-wrapped with spade terminals).
Or, should I declare victory, and leave well-enough alone?
Thank you,
-Henry
Im afraid I cant help you with the electronics, but I have found over the years, that good stands and positioning are allmost as important as good speakers.
Great work btw. I love recycling/ upcycling. Too much stuff gets trashed these days.
Great work btw. I love recycling/ upcycling. Too much stuff gets trashed these days.
It's the room, stupid! ;-)
Yes!
A couple of years ago, I attended a seminar on recording technology by Joe Weed, this legendary producer, the guy with the golden ear who always gets the perfect sound. All attending audio geeks were eager to get Joe's take on the latest advances in microphones, DAWs, digital sound cards, and things like that.
Instead, Joe talked about the room. The room matters as much as everything else he said! Everything else -- combined!
The "Forehead Girl" speakers
BTW, I've been listening to these more, and am starting to think of them as the "forehead curl" speakers. After this rhyme, of course:
Almost all material sounds fantastic, amazing. But every once in a while, there'll be a song that just goes all raspy/harsh in the lower treble register.
I haven't yet determined which driver is responsible. It's like a heavy grain sound... worst in songs with white noise. Guitar distortion is insufferable, Nirvana is impossible.
So there's definitely more work to be done. Either the Fostex FW137 woofers have some pretty unpleasant harmonic artifacts when driven full-range, or else the 4.7uf caps may be the wrong choice for these cheap tweeters. Or else one of the caps is bad (?) Or... (?)
Another thought: one of the terminal cup spring clips is broken, and the wire is just kind of stuck in there for the time being. Maybe a certain frequency makes the wire vibrate? Okay, that's a crazy theory. But it's that kind of bad... when it happens, you can't get the volume down fast enough.
Anyway, I need to listen more, and give them some time to break in.
Thankfully, that's not going to be a hardship ;-)
Thanks for the comment, Dave,
-Henry
Yes!
A couple of years ago, I attended a seminar on recording technology by Joe Weed, this legendary producer, the guy with the golden ear who always gets the perfect sound. All attending audio geeks were eager to get Joe's take on the latest advances in microphones, DAWs, digital sound cards, and things like that.
Instead, Joe talked about the room. The room matters as much as everything else he said! Everything else -- combined!
The "Forehead Girl" speakers
BTW, I've been listening to these more, and am starting to think of them as the "forehead curl" speakers. After this rhyme, of course:
There was a little girl who had a little curl
Right in the middle of her forehead;
When she was good, she was very, very good,
And when she was bad she was horrid.
Right in the middle of her forehead;
When she was good, she was very, very good,
And when she was bad she was horrid.
Almost all material sounds fantastic, amazing. But every once in a while, there'll be a song that just goes all raspy/harsh in the lower treble register.
I haven't yet determined which driver is responsible. It's like a heavy grain sound... worst in songs with white noise. Guitar distortion is insufferable, Nirvana is impossible.
So there's definitely more work to be done. Either the Fostex FW137 woofers have some pretty unpleasant harmonic artifacts when driven full-range, or else the 4.7uf caps may be the wrong choice for these cheap tweeters. Or else one of the caps is bad (?) Or... (?)
Another thought: one of the terminal cup spring clips is broken, and the wire is just kind of stuck in there for the time being. Maybe a certain frequency makes the wire vibrate? Okay, that's a crazy theory. But it's that kind of bad... when it happens, you can't get the volume down fast enough.
Anyway, I need to listen more, and give them some time to break in.
Thankfully, that's not going to be a hardship ;-)
Thanks for the comment, Dave,
-Henry
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