Compression drivers/waveguides for home HiFi

[AllenB]

I have been reading Dr. Geddes, and I want to try some waveguides to control dispersion. This also means I will want 1" compression drivers (like the Geddes ones) but this seems conflicting in a home situation.

Will they respond well to low power, like SET? I've heard these drivers sound effortless due to their ability to play loud, but I feel I could only take advantage of this by forcing them to cross low.

I want them to take the place of Fostex drivers that are doing mid-bass and up, but to me it just seems chalk and cheese.

[Robh3606]

I want them to take the place of Fostex drivers that are doing mid-bass and up, but to me it just seems chalk and cheese.

Depending on how you define mid bass, that may not be a good idea. Generally you want a 1" driver crossed over above 1K or so and then you have the issue of the size of the waveguide if you want to go below that. Many 1" drivers won't even play to 800hz at least as far as the minimum crossover points recommended by the manufacturer.

Rob

[AllenB]

Good point, but that's OK, I could cross higher if necessary.

[Robh3606]

What are the crossover points for your Fostex drivers now?? Are you considering droping the waveguides on top of the Fostex's for a 3 way??

Will they respond well to low power, like SET?

Depends on how much padding you have to do and if there will be any passive compensation for the waveguide. They don't need much power but you can eat quite a bit of what is available just padding them down. Usually you are looking at at least 10db depending of the sensitivity of the midbass driver. If you start with 2-3 watts your looking at 200-300 miliwatts at the driver. With a 110db driver that will get you to about 104db or so. That would be at 1 meter so to me not enough for you???

Rob

[AllenB]

I wil be listening from 3-4m so 104dB is a good start. I should be able to pick up a few dB as I have some amp options.

I wasn't thinking of going 3-way, but I might consider it while I learn the new driver's capabilities and find a way to go 2-way.

Any idea how the CD would sound above a fostex?

[Robh3606]

Any idea how the CD would sound above a fostex?

Potentially very good based on my experience using 8 and 10" mid range drivers between 300 and 1.2-1.6K. I have two set-ups using 10" drivers one using a 1" driver the other a 1.5" CD and they both sound very good with the cone drivers.

What driver are you using?

Rob

[AllenB]

fe108ESigma. Although I am leaning towards 2-way to eliminate a crossover, maybe in the back of my mind I just feel bad chopping up the 108's spectrum because it is such a good driver. Still, it does leave me longing for something a little more nimble in the top end.

[gedlee]

I don't see what the compression driver has to do with the crossover point. To me this frequency is dictated by two things: The directivity of the woofer at its upper end and the low-end directional control of the waveguide. The compression driver is pretty much irrelavent.

Now in Pro apps this is different because you are using the compression driver near its limits, but in home use these drivers have so much extra capacity that over extending them is simply not going to happen.

And I do not see what limits any driver at low levels:

Will they respond well to low power, like SET? I've heard these drivers sound effortless due to their ability to play loud, but I feel I could only take advantage of this by forcing them to cross low.

While I am not a big fan of tube amps, I see no reason why a very high efficiency is not an ideal match for a low powered one.

[ttan98]

Try using, B&C DE250 compression driver with RCF horn H100(get it from loudspeaker plus, quite well priced less than $50 each) every good matched combo, little or no equalization required.

I have both, very dynamic and smooth.

[gedlee]

Originally Posted by ttan98

little or no equalization required.

I've said this before, but it is worth repeating. Any CD device must have equalization. That's because with CD its power response must be falling along with its axial response. If it "doesn't require EQ" then it is not CD.