Worthwhile tweak to Heresy 1.5 with Scale etc

[Antone]

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. 

Edited August 11, 2020 by Antone
Grammar, spelling and clarity improvements

[Antone]

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

 

[JCBOHL]

Antone, I have been following you work. Nice. The one thing I am confused over is the porting. The diameter of the port is 3" ID and the tube is 3" long. There is a mention of an elbow. Is this 90 degrees? Which way is it facing and is there an extension off of the elbow. I am not seeing the picture. Thanks.

[Antone]

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. 

[Antone]

On 3/17/2021 at 7:41 PM, JCBOHL said:

Antone, I have been following you work. Nice. The one thing I am confused over is the porting. The diameter of the port is 3" ID and the tube is 3" long. There is a mention of an elbow. Is this 90 degrees? Which way is it facing and is there an extension off of the elbow. I am not seeing the picture. Thanks.

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. 

[Antone]

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. 

[OO1]

did you ever have a chance to try out  a K-55V , I think you would be very pleased .

[Antone]

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;)

[pcbiz]

On 5/16/2022 at 7:25 PM, Antone said:

This is by far the sweetest, best imaged and most transparent and neutral sound I have achieved with my Heresy’s. 

 

Good work. Materials definitely make a sonic difference. I changed the tin terminals on my 'crossover to driver' connectors with copper terminals for my vintage La Scalas. The sonic upgrade was pleasantly surprising. I need to start taking measurements like yours so I can quantify these experiments.

[MEH Synergy]

. 

[pcbiz]

23 hours ago, Antone said:

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;)

 

The K-55V will definitely work on the Heresy 700 Hz horn. That's what I had in mine.  Crites sells them as the Atlas PD-5VH Alnico Midrange driver. $365/pair.

 

I also got a nice boost in presence, detail and volume from my K-55Vs by swapping out the steel crossover to driver wiring with 10AWG pure copper wire. It actually improved every driver in perfect sonic proportion. Give it a try if you'd like, and share the before and after measurements if you can.

[Antone]

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. 

Edited May 18, 2022 by Antone
Content enhancement/ precision accuracy

[Antone]

Pcbiz,

Thank you, Sir. 

[OO1]

, some 1981 Heresy 1 were manufactured with the K-55V , you can also use the K-55M  

[Antone]

001,

Thanks for the info!

[pcbiz]

I took a similar approach with my Heresys, but I purchased the ALK Universal crossovers, as I have no crossover design skills. Changing out the wiring to 10AWG and upgrading with new SMAHL tweeters were big improvements with my newly capped stock crossovers. However, upgrading to the ALK crossovers was a substantially larger and very engaging upgrade in sonics.

[Tinnitus]

On 5/20/2022 at 8:08 AM, pcbiz said:

I took a similar approach with my Heresys, but I purchased the ALK Universal crossovers, as I have no crossover design skills. Changing out the wiring to 10AWG and upgrading with new SMAHL tweeters were big improvements with my newly capped stock crossovers. However, upgrading to the ALK crossovers was a substantially larger and very engaging upgrade in sonics.

I’m changing the wiring from crossovers to drivers in several speakers to 12AWG. I’m using PE 095-672 gold crimp (and soldered) terminal 14-12 AWG #8 at the crossover (good fit). The 12AWG fits the holes in the K33 and K22 and can be soldered without need of a connector. The K55V with push pins will accept the 12AWG (tinned). 

Anyway, my issues are with the K55V and K51V (both soldered terminals) and the K77s. The holes on the terminals are too small to accept the larger wire and too delicate to attempt enlarging the holes.

Did you use additional connectors at these points to accommodate the 10AWG?

Thanks

 

[pcbiz]

4 hours ago, Tinnitus said:

I’m changing the wiring from crossovers to drivers in several speakers to 12AWG. I’m using PE 095-672 gold crimp (and soldered) terminal 14-12 AWG #8 at the crossover (good fit). The 12AWG fits the holes in the K33 and K22 and can be soldered without need of a connector. The K55V with push pins will accept the 12AWG (tinned). 

Anyway, my issues are with the K55V and K51V (both soldered terminals) and the K77s. The holes on the terminals are too small to accept the larger wire and too delicate to attempt enlarging the holes.

Did you use additional connectors at these points to accommodate the 10AWG?

Thanks

 

 

I separated the 10awg into two strands on the end. The half strands fit the terminal holes perfectly. You can cut or twist the excess.