Isn't the entry of the conic section about 13/16" in diameter?Originally Posted by Panomaniac
GM
Isn't the entry of the conic section about 13/16" in diameter?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
I have been totally occupied with my main profession, so no activity here for quite sometime. But I go thru the posts.
Two issues came to my mind after going thru this thread......
First.....yes the bug screens reduce the throat exit area by around 25% to 50%. So will not the removal of this restriction affect the FR-curve as this changes the throat loading ? For this size of compression drivers, the throat area will be sensitive to changes of 1/10th of a mm^2 loading even !
2nd...... while all these drivers were spec-ed, these bug screens were sitting there in the throat passage or they were just added on later just as 'a ' bug screen ? Hard to believe that these meticulous manufacturers were not taking this into account while designing them.
I had once gone thru a phase similar to this around 3 yrs back while trying to restore a pair of Goodmans Midax drivers (for a friend of mine), one of which had a completely blocked/clogged screen, and in huury I had decided to do away with it. And I still remember that when I had A/B-ed it with the normal good one, though at first shot it had sounded cleaner (more air) than the standard one, it quickly became apparent that it had shifted its FR linearity. There was a definitive peak in the lower spectrum, which was not there in the other one. I had very quickly (& carefully) cleaned the clogged screen & fitted it back. And the sound was back. I think proper loading at the throat is responsible for the flatness of the response spectrum of the driver concerned.
The Midax is a peculiar driver, in the sense that it (the throat chamber) is tuned for a range between 1k-5k Hz only. May be due to this it was more sensitive to such changes. But after this incident, I have never tried to tamper with a compression driver again, especially when it is from a very reputed maker.
I couldn't reach the screens on my 604's for some reason...theres a metal piece with some small round slots in it just behind the phram and I couldn't figure out how to move it. So all I did was the Markwart suggestion of removing the loading caps and felting the inside of the rear covers. I used the peel and stick loop part of some velcro I bought and covered the whole inside of the rear cover. It has excellent stickyness so it'll stay where it was put. I will admit it was close to a vast improvement in clarity and soundstaging although one other point was that when I opened up the push on connector phram the red dot was by the terminal on the right side of the phram and when I opened up the other speaker phram the silver L1 was by the left side terminal of the phram so for once in their life both the red wires from my crossovers are hooked to the proper terminals. I'm still trying to dial them in but I like how much nicer they sound now.Thanks Jeff.
Yes......felting the inside of the back covers is really very good for home-use, as it will mellow down that almost jarring Altec brightness quite a lot.
My Valencia's that I purchased new in the 70's did not come with bug screens so if bug screens were taken into account with the design the question is which design home or pro?
This is interesting info..., at least for me. Does the Valencia use a standard Altec crossover or it has its own specific model ? Like many others here I am no Altec expert to know all these, but if the bug screens were taken into account, then the xover should be model specific.
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