New Heathkit AS101 owner - First post.

[Earl K]

<<<<SNIP>>>>
But I do have a problem. I use an audiophile pressing of Larry Carlton's, "Alone, But Never Alone" as my component test source since I know it well. The lows and mids are spectacular and are obviously well engineered. But there are small chimes used in several songs and now I notice their presence seems muted. They just don't sparkle the way I'm sure the recording engineer intended. I never noticed it as much before because my other amps must have muted everything else to a similar degree.

So I'm wondering if this high end limitation is a function of the stock XO, or the 806A/811B. I remember reading a bunch of Zilch's threads where he pounded on the high-end roll off of the Valencia's (and Heathkits too). He seemed to think that a reworked XO would help. If that's the case then my bi-amping with active crossover might alleviate the issue.

Thoughts?

I find tweeters ruin the imaging of horn based systems ( unless crossed above 10K ) / so I discourage their use .

Also, since I like the sound of aluminum diaphragms much more than the plastic type frams, I'd be inclined to seek out an 802 / 902 variant that could work with your AS101's .

( Strictly speaking ),a reworked XO is not going to bring back something that's missing ( though with biamping, one could conceivably suppress the midrange enough to give the HF a fair chance at being heard ) .

One needs to suppress the midrange something in the order of 12 to 15db to get the the HF on an equal footing . See ( Zilchs work ) below ;




If 14db of midrange suppression is employed, the whole horn circuit will be too low in level when compared to the woofer . It'll be something like 90db HF over 96db LF ( clearly a mismatch between the highs & lows ) .

Using an 8ohm driver ( or 8 ohm diaphragm in your existing 806 ) over an 16 ohm woofer helps reclaim most of that differential . That'll necessitate a rework of the crossover to accommodate the mixed 16 ohm and 8 ohm loads ( LF & HF respectively ) .



Reworking the stock 101 Xover would mean employing something like the HF leg of this following network ;



Then one would want to build up Altec's ( classic ) midrange suppression network ( the HF portion of the following compensation network ) and insert it inline ( after the Lpad I suppose ) .