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Wednesday, June 13, 2012

Hitachi Foam Fix (2)

A first listen was encouraging at low volumes,
but when I put the screens back on and listened louder,
it became harsh or perhaps 'transistor-like' in sound.
Also the bass was as perhaps expected, somewhat lacking.

I re-examined the screens,
and to my disappointment, noticed that as well as cloth,
there was a backing support screen of plastic (molded)
with tiny round holes through it.
It looks as though this backing screen blocks about half the output of the mid and tweeters.
I decided to cut out the backing screen, leaving only the cloth, for the tweeter and mid sections.

 Here's some pics of the operation:

The grill, with the backing plastic grating seen from back:

Turns out that the cloth is glued to the grating.
But the grating is so flimsy it can be easily cracked and broken out,
and peeled off from the back inside, leaving the front cloth and grill mostly intact.

You have to take care to leave enough of the backing grate behind around the edges,
so that the cloth is still supported and retains its basic shape stretched across the gap:

From here, I had to re-glue the remaining framework holding the cloth,
back to the hardshell frame.
There was some problem with the superglue leaking through the cloth,
but other more experienced DIYers might do better on this than I did.
In fact, in subdued evening lighting, the grill doesn't look much different/worse,
than it did before.

But my goal was achieved - the removal of the blocking support grillwork,
leaving the light, cloth cover, so that the tweeters/woofers could project sound cleanly,
unhindered by a diffusing grill or reflecting surface.

I will give the speakers another listen at moderate/high volumes,
and decide whether to keep them as is, (and do the crossover),
or save the tweeters for the Kenwoods, and junk these babies.
If I do the crossover, I may still replace the woofers with something better.
I do like the cabinets with their non-rectangular shape.
The bottom 2" stands are plastic, and not exciting.


Well, I thought it through again,
and decided that the best thing about these was the mid and tweeter,
and the only way to increase bass response was to find big bad 8" woofers, and abandon the ones I re-surrounded.
Maybe those will work in a larger case, so I won't throw them away.

But I've decided to cannibalize these for the tweeter and midrange,
and I've inserted them into the Kenwoods (see other thread).

The box here is a good design, but simply too small,
and aren't giving bass any better than a paradigm or mission 717 or probably any good near-fields.

It would be nice to copy it in a larger format, but thats a faraway project.

For now I'm sticking the Kenwood tweeter/midrange in this box,
and sticking the higher power/better tweeter/mid in the Kenwoods.

This is a much better match than what I was doing over there.
It has improved the sound of the Kenwoods immensely already, so for $30 I got 2 good tweets and 2 good mids.
I think I'm ahead.

I don't know what to do about a crossover for this cab,
I have just left the two caps in for now.
With such cheap speakers it will have to be a low priority.

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