Heresy II info please

[Norval]

Hi all Klipsch enthusiast

I have a set of Heresy II's that belonngs to a friend that I have to repair. Its still in very good shape overall, the only problem is a distortion at around 120 to 130 Hz at high volumes on the one speaker. I tested it and localized the problem to be bad coupling of the bass driver to the cabinet. So I replaced the gasket and replaced the screws with t-nuts and bolts and the problem seems to be cured.

Now questions:

1) The boxes are made from 15mm plywood, and no internal bracing to make the cabinets more sturdy. Are there a reason for that? Would it do any harm to brace the cabinets inside? I'm asking the question since I know some like Castle Harbeth for example build their boxes to resonate. Would that be the same with the Klipsch?

2) There are very little internal damping (stuffing) inside, which is quite uncommon for sealed boxes. Any reason for that? Would it be benificial to put more stuffing or should I rather leave it as is?

Thank you so long []

[Groomlakearea51]

If they are H-II's, they are made from Medium Density Fiberboard (MDF) and covered with a .22-.25 mm thick veneer.

There should be four horizontal braces parallel to the sides at the junction of each panel and four along the rear of the motor board. They are made from 3/4" birch plywood strips, and glued in place. If not, then someone has removed them (or they have come loose and laying on the cabinet floor...). Horizontal and vertical braces (parallel to the rear panel) were not used because the rear panel is recessed into a dado/ routed out cut and mounted flush and tight on the rear edge of the panels. Both the rear panel and the motor board are "glued" and permanently installed.

There should be a piece of open cell "foam" inside the cabinet, the same width as the cabinet itself, and folded over the woofer. If that's missing, then someone has also removed it and it should be replaced. No further dampening material should be used or you will alter the characteristics of the Klipsch design.

Hope that helps.

[Dflip]

If you add additional bracing then it takes up space. This effects the inside volume of the speaker which is set to work with the chosen woofer.

Here is some info on calculations etc.... A lot of reading, but some interesting facts once you go through the links.

http://www.lalena.com/Audio/Calculator/Box/

http://www.kbapps.com/

http://www.audiogrid.com/audio/

[Norval]

Thanks Groomlake that info helps a lot. It does seem then that someone must have removed some of the stuffing inside the box. There are bracings in the corners of the boxes, it was just strange to find no additional braces, even with the rear pannel recessed but it doesn't seem to be a problem though. I have though decided to insert a cross brace on the rear and side panels just as an extra measure.

Dflip thanks to you as well for the info given, but I'm very familiar with speaker box design myself. This being a sealed design means that a little extra internal bracing shouldn't effect the speaker response since it should take up a very small percentage of internal volume.

I've now finnished the speakers with the few minor mods, and new gasket and it sounds quite good foor the money. Very different from my own Chario Accademy 1's but I can see why so many like them.