After the positive results with Cardas 15.5 AWG Litz wire, I evaluated a higher quality solid core speaker cable to replace the internal wiring of the SDA SRS 1.2TL's.
Figure 1. Spool of bulk AudioQuest GO-4 speaker cable.
I ordered 80 feet of GO-4, but AudioQuest threw in an extra 4 feet for free. I used part of the excess to make some nice wire jumpers for my SDA SRS's. GO-4 retails for $15 per dual conductor foot. This is 3X the $5 per dual conductor foot cost of the Cardas 15.5 AWG Litz. Other differences between the two are:
Cardas 15.5 AWG Litz Wire
Wire insulation (dielectric): Polyurethane.
Jacket material: Teflon.
Conductor Count: 48 strands.
Conductor material: 99.9999% pure copper.
AudioQuest GO-4 15 AWG Hyper-Litz Speaker Wire
Wire insulation (dielectric): Nitrogen foamed polyethylene on positive conductors, partially conductive carbon loaded polyethylene on negative conductors.
Jacket material: Polyvinylchloride.
Conductor Count: 2 wires - 1 x 17 AWG, 1 x 20 AWG.
Conductor material: 99.999999% pure copper with highly polished surface.
GO-4 is actually a little smaller than standard sized 15 AWG wire. GO-4's 17 AWG wire has a cross-sectional area of 1.0398 mm^2 and the 20 AWG wire has a cross sectional area of 0.51886 mm^2. This adds up to 1.55866 mm^2, which is 6% less than the 1.65206 mm^2 cross-sectional area of 15 AWG wire. GO-4's cross-sectional area is 6% larger than the Cardas 15.5 AWG wire. GO-4's cross-sectional area is 19% larger than the stock 16 AWG wire (1.30762 mm^2).
GO-4 cable contains four solid conductors: 17 AWG and 20 AWG positive conductors with red polyethylene insulation and 17 AWG and 20 AWG negative conductors with black polyethylene insulation. The weight and stiffness of GO-4's solid core wire made it much more difficult to work with than the Cardas wire. WBT gold-plated copper quick disconnects were used to terminate the driver and tweeter ends of the wires.
Figure 2. WBT QD25 gold-plated copper quick disconnect.
Figure 3. GO-4 trash pile.
I did not use a lot of material that I paid for: foil shield, Dielectric Bias System wires, and the thick PVC outer jacket. I sent an email to AudioQuest asking what percent of GO-4 cable's cost was attributable to the unused parts. They said they didn't know, but that most of the cost of their cables is attributable to the conductors.
Figure 4. Fun times with cable making.
Figure 5. To support the weight of the tweeter wire harness, it was bound to the three cabinet braces in the
tweeter area with cable ties.
Figure 6. Completed driver wire harness, comprising $300 worth of GO-4 wire.
Figure 7. GO-4 wire installed in right SDA SRS 1.2TL.
I wondered why the driver harness wires were so long. The tweeter and binding post harness wires were just long enough to provide a few inches of slack to allow getting your hand between the cabinet and tweeters and between the cabinet and the crossover plate when removing them. The driver harness crossover connector was 15" longer than required and the individual driver wires were 11" longer than required. I maintained the stock driver harness wire lengths because I did not know if there was an electrical design reason for the extra lengths.
In order to prevent stress on the soft metal connection tabs of the drivers and tweeters, the GO-4 wires were gently bent so that the quick disconnects were perfectly aligned and parallel with the driver and tweeter connection tabs. To make sure there was no disconnect slippage during installation of a driver, a mirror and flashlight were used to inspect the bottom of each driver after placement in the baffle. The ends of the wiring harnesses that connected to the crossover board had to be gently bent in such a way that no stress was placed on the board when it was reinstalled in the baffle.
Figure 8. Cardas wire installation in home theater system SDA SRS's
The Cardas driver, tweeter and SDA inductor wire harnesses found a new home in the home theater system's SDA SRS's. I had to reorder the tweeter harness connector pins from T3-T1-T4-T2 (1.2TL) to T1-T2-T3-T4 (SRS). The remaining seven SRS wire harnesses, as well as the wire in my three pairs of CRS+'s, will also be replaced with Cardas wire.
Test signals at 100 Hz and 1000 Hz were passed through a 22" section of the stock wire, a 22" section of Cardas wire and a 22" section of GO-4. The stock wire was the low frequency + wire from the binding post harness that had seen many years of use. The Cardas wire was the low frequency + wire from the binding post harness. It had been conditioned for 96 hours on the Cable Cooker and in use for music play for 220 hours. The GO-4 wire was a 22" section that was conditioned for 24 hours on the Audiodharma Cable Cooker.
It is easier to see differences in the Fast Fourier Transform noise spectrum plots if they are downloaded and viewed in succession.
Figure 9. FFT plot of stock wire with 100 Hz test signal.
Figure 10. FFT plot of Cardas wire with 100 Hz test signal.
Figure 11. FFT plot of GO-4 wire with 100 Hz test signal.
Figure 12. FFT plot of stock wire with 1000 Hz test signal.
Figure 13. FFT plot of Cardas wire with 1000 Hz test signal.
Figure 14. FFT plot of GO-4 wire with 1000 Hz test signal.
There were substantial differences in noise density and amplitude between the stock wire and either the Cardas or GO-4 wire. The noise amplitude and density differences between the Cardas and GO-4 wire were not substantial. The GO-4 showed slightly less noise around the test signal frequencies than the Cardas.
The GO-4 wire was burned in with music play over 148 hours. However, no changes were heard after 75 hours. I did not use the Cable Cooker for two reasons: 1. I wanted to hear the changes in the wire as it burned in. 2. GO-4 is difficult to handle and I did not want to do multiple cook-install-listen-remove-cook cycles.
The right speaker was completely rewired with GO-4 and compared to the Cardas-wired left speaker. My initial impression after comparing the brand new, unbroken in GO-4 on the right to the broken in Cardas wire on the left was that the GO-4 was about 10% better in imaging properties, clarity and detail. There was a slight blurring of bass detail and articulation that went away after 4 hours of music play.
After the left speaker was rewired, both speakers were burned in for 148 hours straight using a combination of CD player and radio tuner. I did not hear any improvements after the 75th hour. During listening sessions, up to the 75th hour, I was continually struck by new sounds in familiar evaluation media that I did not remember and that I had not documented on previous sound stage evaluation charts or listening notes. I used the CD player's "rewind" button many times to restart a song intro or to replay a passage that had a sound image that was new, or much different in loudness, clarity or character.
On simply miked recordings with few sound images, the GO-4 showed only a small to modest improvement in detail and clarity over the Cardas wire, but showed modest to significant improvements in image weight, ambient effects, bass articulation and bass detail. On complex orchestral and choral recordings, and on recordings that had complex percussion tracks, the GO-4 earned its 3X cost premium and left the Cardas in the dust with significantly more resolution, enhanced depth and enhanced holographic three-dimensionality. Spatial improvements were more apparent with analog media than with digital (CD and SACD).
The GO-4 was significantly better in tactile sensation on all recordings. There was more vibration not only against my body, but also coming through the floor and the listening seat. The increase in air pressure and floor vibration was noticeable in rooms adjacent to the listening room. In summary, GO-4 provided "thicker" and clearer sound. Such good wire and Such Good Sound.