Search the Community

In living this past year with the mods to my Heresy 1.5 for gravitas, scale and flat response (c.f. my last post), I discerned room for improvement. The lower treble still needed some smoothing, and the stereo image was unstable: moving my head quite slightly would sling the upper few octaves all over the place, and the left-right balance was never totally satisfying. (Bass was awesome, however.) The new drivers and cabinet porting had made huge improvements in the extremes of the audio band, but I wanted to try subtle changes to the crossover in order to fix smoothness and phase in the midrange and treble. I used the trial-and-error method with a real time analyzer, pink noise, and calibrated microphone while leaving the balancing network board external to the cabinet so as to see the results of crossover component value changes immediately in the response graph. Significant improvement was achieved by changing the tweeter section to a 7 kHz, 18 dB/octave high pass from last year’s 6kHz. This tipped up the response over 1.5 dB, contrasted to the previous x-over, from 15 kHz up to 20 kHz. This also made for less summing between the tweeter and squawker where their responses overlap. The squawker needed to have its top end slightly attenuated. I had been using the stock Klipsch configuration for the squawker, substituting a high quality poly film-and -foil capacitor of the stock 2 muF value for the original paper-in-oil can and continuing to use the number 2 tap on the T2A autotransformer. This works well to meld with the woofer but does nothing to calm the squawker’s upper end ( mortite on the horn has been tried by some on this forum for that), so I tried the easiest obvious thing, which was to shunt a capacitor across the squawker’s inputs. This is a way to knock highs off a driver’s upper end by essentially shorting only the highs to ground. The second order, low pass filter (which included a 33 muF cap added to the Heresy 1’s first order woofer crossover- i.e. just an inductor) that Klipsch used on the Heresy 1.5’s and 2’s woofer x-over is a handy case in point. Comparison of Klipsch’s schematics for the Heresy E and E2 crossovers indicates a phase difference introduced by the addition of the woofer cap, by way of the schematically notated inversion of polarity between the woofer and squawker in the Heresy 1’s E crossover (which inversion is absent in the Heresy 1.5’s and 2’s E2 crossover). Higher order phase difference will come into play later. The first value I tried in my squawker section was 18 muF, which sucked out too much low midrange. Trying successively smaller capacitor values, I arrived at near 5 muF in order to start attenuating high enough in the squawker’s range. RTA showed that the roll-off slope was a bit too steep, so I tried different audio grade resistors between the 5.1 muF cap and ground while watching the graph. Putting resistance between the 5.1 muF cap and the negative squawker input-i.e. signal ground-effectively reduces the overall amount of those particular highs allowed through the cap which get shorted to ground, shallowing the roll-off. Best results were obtained with the 9.1 ohm, 10W resistor I had in store. (A Mills non-inductive 12W resistor may be a better choice. ) Interestingly, the resistor’s insertion smoothed the bass response on the graph. The midrange response now is beautifully neutral, full and rich but never shrill; the treble is sweet, extended and clear. Another benefit of adding the cap to the squawker circuit is the phase shift (around 90 degrees ) that it contributes to the squawker, making it blend more coherently with the other drivers. The stereo image is solid, the soundstage stable, with instruments startlingly precisely located. Channel balance is now rock steady with no stereo wandering. Placed 2 feet from front wall, no subwoofers are necessary or wanted. Schematic for this latest and greatest mod is included. Drivers specified on this schematic and in my previous post are easily available online. Porting dimensions and woofer crossover values remain as per my previous post. These Heresy’s sound big, accurate and serious. Gravitas, exciting scale, powerful bass, beguiling mids, crystalline highs and imaging. Happy listening.

WALNUT FINISH, $599 {SERIAL #'S : 8616385, 8616386...} SOLD SOLD SOLD ..... I'm probably going to hate myself for doing this, but seeing as I've had my Forte speakers boxed up for the last 14 years, (much longer then i used them), i think it's time to sell them to someone who will appreciate them once again... I've seen quite a few sets of these for sale over the years, but never in the condition of the ones that i have....NO rusty screws,beat up cabinets or pushed in woofers, or passive radiators.. I have taken really good care of these ! I don't have children, so no little bundles of joy have poked their sticky little fingers where they don't belong ! lol ...and i don't smoke cigarettes so they won't smell nasty either... Did i mention that they are in the original boxes ?!!! So if you've been waiting to find a really good pair, and live within driving range of the Jersey shore, this is your chance.. An hour and a half from Philly, and an hour from N.Y.C., (assuming light traffic...) Exit 109 on the parkway, near Red Bank..... I'll miss them, i'm sure, but i do still have Klipsch bookshelf speakers, sound bar with sub for tv, and speakers with sub for computer, so i'm still pretty well equipped.. 🐵 I thought that i had replaced a passive radiator 20 years ago, but looking at the receipt from KLIPSCH for $125, it was one of the woofers...Matching speaker was sent directly from Klipsch after i supplied them with my model and serial numbers..