You can do more, but it's only for crazy people like me
. You open the back chamber of the driver. This prevents resonance peaks that occur in the chamber. Not recommended for expensive, rare drivers. Sometimes it's enough to glue a thin piece of foam to the cover of the driver from the inside.flater frequency responce and i use it as dipole in my openbaffle.
Beyma CP-755Ti, CP-350Ti, Supravox 215-2000(although it has a bit of a rise, off-axis it’s not bad), Fostex FT96H.
Depending on your tolerance for flatness or lack thereof, the still require some degree of voicing.
As I said, the Supravox + Beyma 755 measures quite flat in room through the crucial range and has a gentle roll off at the top. When I used a digital crossover, the only thing I did was shape bass a bit, but an amp change resulted in that being unnecessary as well.
You can use a passive preamp or with tube buffer/ gain stage from hattor audio, superb khozmo parts e.g volume control my tip
hattor.com
For reference, below is the listening position response of an Altec 802D / 511 horn I took just minutes ago (the major vertical divisions are 5dB) - done properly, these vintage drivers leave nothing to be desired compared to more modern ones.
Thank you. I ran upstairs to check out the dipole woofers on my last main speakers of 34 years. Apparently Mark Gilmore did that correctly when he designed them. Appreciate the shareYou can do more, but it's only for crazy people like me
Kinda like Apogee by Clarysis... (which are my replacements for those)Carver by Gilmore ....
The usual 1/6 octave in REW. The slight shelf below 1 Khz fills in to be flat when the woofer horn is active. This was taken from the listening position.
AgreedClarysis has done a great job on build quality and looks while retaining the obvious ..
Love how you offset the amplifier to fool standing waves in the room
All the schematics I've seen have 12dB slopes or more.
Since it needs to be 12dB, there will be also a 12dB insertion loss. You'll need some kind of gain I suspect.
FWIW Dept,: the TAD maple 500Hz horn has something going on with the throat that causes a bit of an artifact. John Wolff of Classic Audio Loudspeakers has this corrected with the result being smoother and easier to listen to.
I used to use Altecs with the 800Hz horn back in the 70s and 80s. We used roofing cement to damp them. It really helped them out! These days I'd be temped to use 3M's DP105 damping epoxy.No question the HF horns need to be well damped - in my case (picture below) I cover the entire surface with a thick application of Aquaplas which makes them completely inert. Bondo automotive putty also works well.
Running these Altec horns without adequate damping is a fool's errand.
Why don't you show us what the off-axis responses look like? One of the longstanding challenges with most moving coil dynamic box speakers is that their off axis response can go to pieces rather quickly, a challenge elegantly addressed by Peter Walker in the Quad ESL-63. You can get this to work right, and some designers go to great lengths to do so. But not all. What you hear is a function of the speaker's dispersion pattern across the entire space (direct + room reflections), which in a small room is usually almost instantaneous (unlike a big concert hall where reflected sound can come much later). In short, you are hearing the room as much or more so than your speaker.
These speakers are highly directional full-range horns, and are much less dependent on the room than a traditional box speaker. That is why I don't show the off-axis measurements - because they are largely irrelevant since there isn't as much projection off-axis. Beyond that, the room is very large with excellent acoustics (picture in my profile) and what first reflections there are will be of less influence. Since these horns project direct sound much farther than a box speaker, the listening position is effectively in the near field, even though the listening position is 12' away. The posted response takes into account the total radiation at the listening position.
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