Simple Silver Flutes 2 Way

I built a SET tube amp (a Bottlehead SEX 2.1) about a month ago to use in a headphone rig. It sounds so nice that some high(er) efficiency speakers became a must. Looked around for a fitting design, saw the Decware DM945's, read a review, recognized the drivers, and figured I'd take a stab at an homage to them. Here's my disclaimer: I've never heard or even seen the 945's in the real world. Their cabinetry looks great on the website. If you want beautiful, professionally built stuff, I wouldn't hesitate to give Decware a shot. I just wanted to see (and hear) what I could do on my own.

Madisound was really fast at delivering the Silver Flute 8" 4 ohm woofers, the Hivi RT1C-A tweeters, the 3.9 micro F Clarity Caps (SA), and the binding posts. I grabbed some Home Depot 3/4" MDF and poly-fill NU-Foam from Jo-Ann Fabrics.

Here are a couple of pictures and a rough in-room frequency response chart (no particular absolute db scale on the chart).

They're not broken in yet, but they sound pretty good. :)
 

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Thanks, guys.

The cabinets are based on the Silver Flute recommendation quoted by Madisound - 0.53 cu. ft. with a 2" dia. 3.75" long port. That should put box tuning at about 55 Hz.

The ribbon tweeters are really detailed - lots of sparkle. There is just the single cap for the tweeter crossover and the Flutes run wide open. The drivers integrate quite well and the break-up shown on Silver Flutes' frequency response data sheets seems very benign.

The speakers have run about 10 hours now and the woofers have opened up a lot. Bass sounds much fuller than the frequency plot would imply. I took the measurement in-room about 6 feet in front of the tweeter. I don't think the bass reinforcement from the rear port influenced the measurement as much as you hear it from my normal listening position.

Overall, it's been a reasonably quick and very satisfying little project.
 
Did you try both polarities on the tweeter? That dip is either the inherent rolloff of the tweeter since it prefers 5kHz+, or the phase cancellation of wrong polarity.

I'd personally be really surprised if the RT1C-A is not distorting as you have it running.

You know what- I might even have those files for those drivers. Let me see what I can work up this weekend....

Later,
Wolf
 
Okay - reversed one tweeter and checked it. That wasn't it, but it confirmed the (asymmetric) crossover frequency of 8 kHz. Going a little be lower (bigger cap) might help, but is likely to cause increased tweeter distortion down low because of the shallow slope and it might also exaggerate the woofer break-up at 4 - 5 kHz.

The woofer does dive like a stone above 5.5 kHz - something like 15 dB / octave.

I don't think I can hear distortion on the tweeter right now, but not sure what to listen for. Keep in mind I've only got 2 watts per channel (but good watts!) and I'm usually only listening at 1/3 volume. There is a pretty extended overlap between the drivers (if you put your ear up close to each one).
 

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Yes, O. That's probably because of in-room stuff and my set-up. On the original plot, I had both speakers playing and had the mic hovering out in front. The plot was dancing around a bit. This latest was with just one speaker with the mic about 3 feet in front of the tweeter. Note that the bass rolls off faster in this latest plot - maybe less port information from mic placement and the amp tubes were not warmed up.

Silver Flute recommends 15 L for an f3 of about 60 Hz - that's what's posted on Madisound alongside the description of the drivers. And it matches the dimensions that Decware uses. The bass is actually nice and clear down into the 40's in-room.
 
You could mount the tweet on a separate baffle, close to the woof, you could slide it back and forth for time alignment....................

Perhaps wrap edges of baffle with foam to catch reflections.

If it is more than +/- 1/4 wavelength at crossover, it would be off.
That's really small as the frequencies get up there.

Norman
 
Okay. Here's a quick measurement. This is at the listening position on the couch. It was taken with both speakers playing. I think they're sounding reasonably good, so I'm going to listen to them like this for a while before considering any changes. But I'm always willing to hear any advice from you guys.

Here's a link to a review of the real McCoy from Decware: DECWARE DM945 MINI SPEAKER REVIEW

Oops - Posted the wrong plot. See the next post!
 

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Mini Speaker Review: that was interesting - Shredded Cardboard :eek: good idea!

What to listen for? You can always find songs that sound good, try music that will challenge them. Vocals! Classical!
The weak link in 2-ways is the middle; as much as I like them, they don't hold up to a set of 3-ways, e.g. once had pair with huge Morel mid-range drivers - lifelike! However, they were huge, and "compact" has other advantages.

btw, you did a nice job on your build.
 
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Thanks, O. I steered clear of the cardboard - seemed a questionable choice, though it might provide some diffusion. Went with poly-fil NU Foam batting.

Vocals (male, female - from Linda Ronstadt to the Marriage of Figaro) all sound good to me. Of course, these 55 year old ears have seen some wear and tear. Do you remember the '70's? I remember them as LOUD.

I'll keep listening for a while and see how these do - there's always something to "improve".
 
Been playing with the smaller SF. For the price, pretty darn musical, but it as a couple of issues I was wondering if the 8 has as well. The biggest is insufficient pole piece venting. It will actually whistle with much over a watt. The smaller one really does not want to work above about 1600 and has really bad breakup issues at 5K to kill.

I was surprised that VAS was half what the spec says, and in Doug's box confirms my measured parameters. Measure them, you may find you are missing out on one of their best features.