JBL Brotherhood

[pasadena]

I have added a couple of pictures, one of my stands with spikes and the other a close-up of a machined disc spike protector.

The question I have is what effect will altering the height of the speakers using spikes change resolution and imaging of the speakers?

In the XPL manual it states using stands to help improve the overall sound by lifting the speakers off the ground as well as tilting the speakers back a few degrees towards to the listener.

I have noticed that since adding the spikes, I seemed to have lost some resolution and imaging. I have measured spike clearances on both speakers and all have increased the height of the speakers by 2cm or 20mm all round.

Is there a set rule or has JBL released any literature as to how much spikes should be rasing the stands or speakers off the ground by?

The only solution I have come up with is that the spikes have increased the listenig height to that of above the listening position normally set by using stands only.

If I have increased the height of the stands at the front by 20mm, should I be adjusting the spike at the rear of the stand so as to tilt the speaker more towards (forward) the listener? This is the only change I can think of performing that will fix my resolution and imaging problem.

Any thoughts?

Cheers
Pasadena.

[Steve Gonzales]

I would imagine that any losses you notice will be because of the tilt than the added height. In your highly reflective listening enviroment, you've changed the "sweet spot". JBL's recommendations are guidelines meant to help you set your speakers up properly. They are not etched in granite.

[Titanium Dome]

I would surmise that the sweet spot is above your head (and possibly in front of you) somewhere and what you're hearing are mostly reflections. Try raising the rears as you suggested, probably a few degrees at a time. Keep going past the point where it starts sounding good until it starts to sound worse, then go back in the direction of the better sound again.

That's a start anyway.

[pasadena]

I would surmise that the sweet spot is above your head (and possibly in front of you) somewhere and what you're hearing are mostly reflections.
That's a start anyway.

Hi TD and Steve,

I'll give it a try over the next few days and see what I come up with. Of all places, the rear spike is a pain to adjust but it's gotta be done.

Keep you posted and thanks for the feedback.

Cheers
Pasadena.

[Ian Mackenzie]

The spikes may not be providing a wobble free situation, other then that I agree that silting the system is most likely the cause.

Relatively small movements of the speaker can have profound effects at the listening position. The tweeter should be at ear height or thereabouts.

My suggestion without seeing the whole room is get a rug(s) on the floor immediately in front of the speakers and some wood/furniture / DVD racks along the walls to diffuse and break up the reflective nature of what appears an otherwise live room.

[JBL 4645]

There about 18 years old, well I seem to seeing these in a Hi-Fi shop in Christchurch here in Dorset and they looked fabulous indeed nice catch you got there mate…

…mumbling quietly in jealously , lucky bugger…

Na mate, that is a tasty set-up the floor does need carpeting.