Antone

John, Thanks! There is no subwoofer. That bass bump is largely a result of the listening position being a foot from the wall, which location emphasizes 40 Hz 6+ dB. The Heresy’s are around two feet from the wall behind them. The Dayton Audio PA310-8 Ohm woofers are at least 2 or 3 dB more sensitive than the original Klipsch K 22 E (Eminence) 11 Ohm woofers - and much more athletic. When measuring the speakers in the middle of the room from a yard away that bass hump goes away and the tweeters’ response tilts upward significantly. The 3” long by 3” I. D port tube flattens the bass, moving its peak down in frequency. Picture that wide hump moving to the right almost an octave without the port. Dean, a lot of it is the room. Especially below 700 Hz. You both are right; I need to smooth bass response. I listen at moderately low volumes, and do not mind a bit of “loudness” curve. Though the graph shows a lot.

John, Thanks! There is no subwoofer. That bass bump is largely a result of the listening position being a foot from the wall, which location emphasizes 40 Hz 6+ dB. The Heresy’s are around two feet from the wall behind them. The Dayton Audio PA310-8 Ohm woofers are at least 2 or 3 dB more sensitive than the original Klipsch K 22 E (Eminence) 11 Ohm woofers - and much more athletic. When measuring the speakers in the middle of the room from a yard away that bass hump goes away and the tweeters’ response tilts upward significantly. The 3” long by 3” I. D port tube flattens the bass, moving its peak down in frequency. Picture that wide hump moving to the right almost an octave without the port. Dean, a lot of it is the room. Especially below 700 Hz. You both are right; I need to smooth bass response. I listen at moderately low volumes, and do not mind a bit of “loudness” curve. Though the graph shows a lot.

Antone Posted yesterday at 01:07 AM 🙂 1/3 octave RTA of pink noise: Measured at ear level at listening position approximately 9 ft from motor board: Dayton UMM6 Calibrated measurement mic with REW software: Followingthis schematic: 3” by 3” reflex port

🙂 1/3 octave RTA of pink noise: Measured at ear level at listening position approximately 9 ft from motor board: Dayton UMM6 Calibrated measurement mic with REW software: Following this schematic: 3” by 3” reflex port

001, Thanks for the info!

Pcbiz, Thank you, Sir.

Thanks for your interest. 🙂 The resistors for the L-pad were $5 each, and all the brass machine screws (6-32 at 1/4” long and 1 1/2” long) were a few dollars from the big orange hardware store. I already had a bunch of small poly caps to make the tweeter shunt. The most expensive parts in this experiment were the 16 muF Solen poly caps ($10.50 each). Th e L-pad sounds much better than the autotransformer in the original xover. I will not be going back to using the T2A. I think I will pass on the Furutechs for now, thanks just the same, Westcoastdrums ; ) The L-pad mod alone is only about $21 per speaker, and can be reversibly applied in any otherwise stock Heresy 1 ,1.5,or 2. In the Heresy 1, the squawker polarity may have to be uninverted because of its first order woofer xover. (Inverted in 1.5 and 2) The tweeter conversion took some effort involving attaching a screw-on adapter plate, so, maybe, wait to commit to that mod. Leave the stock tweeter and its xover alone until you have tried the L-pad mod and the woofer replacement. The biggest bang/buck mod is replacing that wimpy stock Klipsch woofer with the (now $130) Dayton Audio PA 310-8 12” pro woofer. Mechanically it is a drop in replacement. It is 3 or 4 dB per watt more efficient and works perfectly in the Heresy cabinet, especially if you replace the 1/2” thick rear panel (8 screws) with a cheap mdf panel and hole-saw out a hole in the lower corner for a 3” long by 3” inside diameter piece of white schedule 40 pvc pipe to tune the cabinet to around 40 Hz. Even without a cabinet port the Dayton woofer sounds much better than the original. Just get even a cheap($12.56)18-gauge 3.0 mH iron core inductor and a dirt cheap($1.04) 100volt 22 muF non polarized electrolytic cap (those components’ quality was good enough for Klipsch) to go with the Dayton woofer’s 8 ohm impedance when you install it, because the stock Klipsch woofer is around 11 ohms impedance, requiring too high an inductance and capacitance for the new woofer. The brass screws are not nearly as important as the drivers’ replacement, cabinet porting and crossover design, but cumulatively, this latest design is worth a try. You will definitely hear a large improvement. If you are handy, able to solder and can read my schematic (and a part$-expr3$$ catalog), why not try the L- pad first then the woofer then the tweeter and then air core inductors and poly caps last? The brass screws are cheap and can be done early on. With them alone you will not hear much difference. The woofer and porting mod you will definitely like. My earlier posts chronicle the mechanical aspects more. The later posts are circuit refinements via trial and error and extended listening tests. This latest mod with L-pad and brass screws is definitely the best sounding so far.

Thanks for the interest and the info, 001. 🙂 I saw “K-52H” actually stamped in ink on the squawker compression driver magnet structure. My Heresy’s were made in 1981. Does the K-55V work on the Heresy 700 Hz horn? I vaguely remember a discussion about another midrange horn lens going down to 600 Hz(?) Am I equivocating a K-55V with a larger (La Scala?) model’s squawker driver? Does BEC (Mr. Crites) sell these? Thanks again for actually reading my post. (It is a slog,I know;)

Watching Danny at GR Research has given me to want to try experimenting with replacing all ferrous components in the speaker signal signal path. I decided to replace with solid brass #6-32 machine screws all the original steel ones in the binding posts and internal barrier strip of each Heresy 1.5. I had replaced the iron cored woofer inductor with a Jantzen air core as of my last post. Although I had years before eliminated the need for the T2A autotransformer in the tweeter branch with a third-order, 7 kHz hi pass filter and a better (Eminence 1001 ASD) tweeter driver which was slightly less sensitive overall than the original K77, for the squawker I was still using the T2A for its 9-dB voltage reduction and eightfold impedance increase, thereby enabling the continued use of a 2-muF poly cap for the 16 ohm-squawker’s required 620-Hz hi-pass filter. Using high quality, low inductance 20-watt bifilar ceramic tube-core resistors I made a -9.8 dB L-pad (@15 ohms) to accomplish approximately the volume reduction that the T2A had yielded. Since an L pad (ideally) does not change the driver impedance it was necessary to increase the hi pass cap to 16 muF (@15ohms) for a 650 Hz squawker hi pass filter. My last post mentioned a 8.35 muF/ 9.1 ohm Zobel shunt across the squawker terminals to roll off (gently) its rising upper end. With the new L-pad I decided to omit the Zobel before measuring. Third-octave pink noise RTA measurements after all these circuit modifications showed a large improvement in overall midrange balance and in flatness from 600 Hz to 4000 Hz. Indeed the Zobel was no longer necessary. However, the tweeter now had a steeply rising high end above 13 kHz, and the L-pad’s lack of phase shift required inverting the squawker polarity, which in turn, required inverting the tweeter polarity, compared to my previous design. I bled off the tweeter rise (+5 dB at 20 kHz) with a 1.22 muF [16kHz] capacitance shunted across the tweeter terminals. This is by far the sweetest, best imaged and most transparent and neutral sound I have achieved with my Heresy’s.

So very sorry. I wasn’t following my thread. There is no elbow. Just a 3” long section of 3” ID schedule 40 PVC pipe. I just posted another tweak with a graph and pix today, November 10th, 2021.

20 Hz to 20 kHz Raw Room Measurement with Calibrated Measurement Mic of pink noise, third octave RTA. Horizontal graph lines are 5 dB apart. Mic at listening position 8.6 feet from speaker. Speaker cabinet 28” from rear wall, 22” from side wall. All upgrade parts available from an online speaker component supplier based near Dayton, Ohio.

Important Tweak to Worthwhile Heresy Tweak Less harshness at high volumes, sweeter clarity and more solid coherence achieved with reversing polarity of squawker to negative, resulting in 180 degrees relative to woofer and by reversing tweeter polarity to match woofer‘s (0 degrees) Small poly film and foil cap across tweeter flattens a spike at its upper end. Used to compensate for a small manufacturing discrepancy between left and right tweeters

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.

Yes , billybob, There are some major differences this time. I port -tuned the enclosure to 50 Hz, lowering F3 by around 20 Hz-no port previously. I chose this latest driver based on its compatibility with the Heresy cabinet, heeding T/S parameters. My previous woofer, Dayton series 2, was 4 dB less efficient and made for a much larger box. My graphs show flatness I could hardly achieve with a 31-band EQ before-no EQ needed now. Consider my posts from years ago superseded. This upgrade is based on much greater experience and measuring instrumentation I did not have before.

Still learning. 🥴 Telling the truth about the results and thought process, though. This upgrade is relatively cheap and easy, and the graphs are much better than stock. I wanted to share my modest success.