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| Re: Dayton Audio/Eminence Full Range Single Driver [message #75563 is a reply to message #75505] |
Tue, 19 February 2013 15:14   |
AudioFred
Messages: 377
Registered: May 2009
Location: Houston
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Illuminati (1st Degree) |
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I've decided to try something different, and so far I like what I'm hearing. These speakers sound very good using the DEQX for equalization and crossover, but realistically how many people have that kind of equipment? If I can make them sound good with no digital equalization and a couple of subwoofer plate amps on the subs, then they become a very affordable alternative for somebody wanting to try an open back full range single driver speaker that has impressive bass.
While there's no way to achieve the flat response in the second graph above, anything that can be done to reduce the level of that broad peak centered about 3.6khz will make them less in-your-face bright, and far more listenable. Many single driver builders incorporate a bsc circuit to balance the bass with the upper midrange and treble, but this has the unfortunate effect of reducing the speaker's sensitivity by several dB, not a good option if you're planning to use them with a flea power tube amp. With these speakers the bass is handled by the subwoofers, so there's less need for baffle step correction, and a simple notch filter can be incorporated into the full range driver's signal path to reduce the unwanted peak. This I did, using a 6.8uF cap, a 0.2mH air core inductor, and a 12.5 ohm resistor, all wired in parallel, and inserted into the positive lead to the full range driver. Works like a charm.
For subwoofer amplification I used a couple of buyout 100W amps that Madisound was selling for $25/ea a few years ago. I bought four and still had two stashed away in the man cave. One hundred watts (70W into the Eminence's 8 ohm impedance) doesn't sound like much power, but this isn't a speaker you would build to listen to Metallica or Mahler, and it works fine.
I'll post some measurements plus some listening impressions after I've had a few days with them.
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| Re: Dayton Audio/Eminence Full Range Single Driver [message #75564 is a reply to message #75563] |
Tue, 19 February 2013 16:41 |
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Wayne Parham
Messages: 18791
Registered: January 2001
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Illuminati (33rd Degree) |
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Sounds like a worthwhile approach.
As an aside, I've always said baffle step compensation is a one-dimensional treatment of a three-dimensional problem, so I'm generally not for it. The two things don't match: BSC tailors uses electrical equalization to improve on-axis response, but since the "baffle step" is actually a side-effect of increasing directivity, this kind of equalization is done at the expense of off-axis response. It's a circuit that makes power response worse, which is not good in any respect for a speaker used indoors. Power response has as much influence on the percieved sound as on-axis response because the reverberent field is so powerful compared to the on-axis sound.
But the truth is I think people often mislabel what is essentially loudspeaker voicing and call it BSC because that has become a DIYers buzzword. Whatever a person calls it, I think if a speaker is a little bit shouty, then some response shaping is probably in order. So what I'm saying is that if a filter were truly implementing BSC, it would make the speaker sound worse. But when it is actually just voicing the speaker, that may very well sound better. Kind of a semantics thing, but an important distinction, I think.
I think that applies here too. If the humpty-dumpty response is too much, then give it a filter to make it better. There's a sort of balance, I think, between a little bit of voicing and what's too much. Some designs clearly go too far in the quest of ruler-flat on-axis response and the speaker sounds dead and lifeless. I think this is largely due to reduced dynamic range and also due to uneven power response. That's common for mini-monitors with a few dozen components in the crossover for response shaping.
Your speaker clearly doesn't fit that description. It's a high-efficiency design with enough dynamics to spare a few decibels for response shaping. That's no different than what is required for CD equalization of a compression driver. Sometimes electrical filters (in addition to the basic crossover splitter filters) are really important in the overall design.
All that to say I think you know what you're doing and have a pretty good handle on it. Should be a killer speaker when you're finished.
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