Loading caps

Hi GM
Your comment about massive suckout if using a 500hz x-over point has caused me a small amount of concern. I just finished assembling new x-overs for my A7-500 using that x-over point!
As None of the components have been soldered, they can be exchanged for a small restocking charge.
Am I screwed?

Say bfish,
very interesting, i did not realize you were contemplating using them in this fashion, i.e., without the big horn. Please post your findings/experiments along these lines, I would love to know.

Russellc

Spin 53 12,
Ithink he meant with the loading caps? correct me if I am wrong GM. On my A7 I have always prefered 500 hz.
What say GM? should I try an 800hz filter?

Thanks,
Russellc

Arrgh! It's kinda of funny after spending so much time researching Altec x-overs to replace the after-market ones in my A7's that I may have settled on the wrong design.
Russellc, you use a 500hz x-over, what can you tell me about the response?
Cheers

Greets!

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For the transition smoothing, are you talking a fine-wheeled dremel/good eye, or machine shop work?

Would a DIY, short "spacer", with its' opening having the same expansion rate as the driver, and thick enough to match the horn ID be advisable, or better to build/buy a matching horn?
..........I ordered new glasses last week.........

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<font size="2" face="Verdana, Helvetica, sans-serif">I used a three stone brake master cylinder hone on a variable speed drill. You can use a spacer if you want. The main thing is for the first expansion to be as free of anything that can create a reflection point since this is the area of the horn covering ~4300 Hz - up.

Then there's all the rest of the tweaks required to maximize the benefits WRT the 511/811 horns, which is to fill in and smooth the transition between the initial CD horn section and the larger exponential section, remove the vertical brace, fill the side seams, either damp or remove the mouth reflectors, damp the bell and horn sides, and of course externally brace/damp it to a fare-thee-well. http://www.hostboard.com/forums/ The downside for Altec fans though is that they no longer have the VOT 'sound'.

I sold mine when I was made an offer I couldn't refuse, but if there's a 'next time around', I'll DIY some simple waveguides and skip all the hassle.

I wish new glasses would cure my loss of visual acuity in recent years. I got new contacts last year and the only difference I could tell was they were more comfortable than my old scratched up ones even though they're a more powerful perscription. http://www.hostboard.com/forums/ Growing old ***** !

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I think he meant with the loading caps?

On my A7 I have always prefered 500 hz.

What say GM? should I try an 800hz filter?

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<font size="2" face="Verdana, Helvetica, sans-serif">I did, I did! http://www.hostboard.com/forums/ It's still typically not flat without them WRT 802/808 if the magnets are still strong because they were voiced back at a time when impedance matching amps was their standard, so you may want to try an R/C network after the attenuator to flatten it/'lift up' the highs and then attenuate them. Better still, as good as the OEM pots are, best to only use them to dial the level in, then bypass them with a high quality fixed 'L' pad.

Me too, though some folks prefer the more laid back sound of a higher XO point, so as always YMMV.

GM

Regarding the horn transition,

It seems that it would be easy enough to make a spacer to more closely match the horn / driver diameters and use some modeling clay to make a smooth transition through the junction. You could even use it to fill the side seems - and the best thing is if you do not like the results, just remove it...

Jeff

Spin 53 12,
did you see GM's reply? He meant with the loading caps. Also, as he said YMMV between 800 and 500...I prefer 500 in my application, as more of the sound is produced by the woofer when using 800hz, it gets a little too laid back for me, so I prefer the 500 point. Dont fret, they will be fine, you can always experiment with other points later. I guess I like what I decribe as a bit more articulate with 500. this is really getting into personal preference area.

russellc

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Originally Posted by GM

Greets!

Me, I just removed the gasket and spaced the loading cap out to the practical limit of its screws to make a two stage loading scheme, so no need to swap screws or add the felt lining.

GM

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So what is the spacer thickness when carrying out this mod? Does this mod work as well as the one where the Loading Cap is removed and the Backing Cap is lined with felt!! Which mod has the greatest HF extention.:confused:

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Originally Posted by GM

Greets!
This brings up another problem with Altec drivers that W.E. addressed and for whatever reason, JBL (the man) didn't copy, is that the mounting joints he chose cause these same reflections in spades if not perfectly aligned and smooth, which with the thick cardboard gaskets and the so-so horn manufacturing QA, really makes a mess of its HF response. I couldn't believe how much better a pair of max tweaked 511s sounded after I did away with the gasket and align honed them with the drivers attached.

I emailed the info back on 3-29, but will resend.

GM

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This problem has been bugging me as well, I had to pop my 808 driver from the 511 horn to re-glue a loose phase plug, rattling like marbles in a tin can!
Noticed the roughness of the interior surface, can't be good. Also ripped the cardboard gasket when pulling the driver. Replace it with a temp that I was not able to align properly, another negative effect on the high frequency response no doubt!
Over the weekend I'll putter around with drivers, remove both gaskets and see if I can hear a difference, an improvement hopefully. Also look into these honing balls.
Cheers