GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s Midbass Project – the grown up time.

Post Subject: Good signsPosted by jessie.dazzle on: 10/3/2010

Excellent news regarding this morning's discoveries.

jd wrote:

"...Are you able to say whether the problem is due to the horn position relative to the room, or to throat diameter relative to the driver diameter?..."

Yes, a stupidly phrased question, but the original requirement for such a small rear chamber (non-existent rear chamber) had me concerned that the driver-to-throat ratio was resulting in excessive throat reactance; the new large rear chamber requirement is an indication that this is not at all the case, which I take as a good sign.

Romy wrote:

"...Now I need to review the entire Macondo in context of the Midbass channels and the ULF channel. Midbass is now a lot louder then Macondo, 7R resistor set it equal but I am not sure how I will reduce the Midbass volume. I would like to do it by dropping loading of the Midbass out transformer..."

Is this because of the way you are driving them?

When testing my one completed mid-bass horn (AK151 into 40Hz Exponential with 8" throat), and powering it from an amp that drives everything from upper bass to HF, the output was not noticeably louder than the rest of the horns. You have DSET amps and I am guessing that you ran the new horns form the outputs that once ran your direct radiating line arrays; is this the reason for the "excess" volume?

"...Meanwhile I need to unpack that Velodine digital crossover, learn how to use it and find a good mono recording to test it; I have some recordings in my mind…"

The Velodyne SMS 1 will allow you to do just about anything, up to 200Hz.

You will need some sort of video monitor to see what's going on and to configure the device (an old computer monitor works well).

You are right to be using only mono recording to evaluate the results when using the SMS 1 (stereo operation requires a second SMS 1). Sending a stereo signal to a single SMS 1 is no problem; the resulting mono output signal can then be sent to left and right channels (left and right power amps). Obviously, if listening to stereo recordings in this mode, the output of the mid-bass horns would have greater amplitude than when fed a proper stereo signal.

Be aware that the operator's manual for the SMS 1 is not clearly written. If using amps that potentially exceed the rated power handling capacity of the AK drivers, familiarize yourself with the SMS 1 for a day while using junk drivers; the SMS 1 used in conjunction with the low-excursion, sensitive AK drivers and enough power is a potential recipe for immediate voice coil meltdown.

jd*

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