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In the Forum: Melquiades Amplifier
In the Thread: Valve Preamplifier for Macondo/DSET
Post Subject: All for nought?Posted by anthony on: 8/25/2020
Well, I decided it was time to start using some  "proper" interconnects between the preamp and DSET's, ordered them and had them delivered.  To date I had been using cheap interconnects from the local electronic shop (literally $6) which should be ok...afterall they are just wire and how easy is it to attach some coax to rca sockets?  All my good cables were either too short or too long for the job so the $6 fellows became the interim solution.  Have been happy with the sound I am getting, was able to dial in a decent sound quite easily using just the l-pads for the upper channels to get a reasonably flat measured response at the listening position.

Put in the new interconnects and the sound is harsh..not nice.  Bass is gone, sound is bleached and irritating even listening at lower levels.  It has been a long time since I've had new cables but I never recalled such a change in sound so I turned down the volume and let them play in the background for a few days.  No change.  Put in the old $6 wires and good sound was back.

This really had me scratching my head so I grabbed the LCR meter and measured both sets of cables.  The cheapies measured 0.4ohm DCR and 0.4ohm AC resistance (100Hz - 100kHz) whilst the new cables an excellent 0.03ohm DCR and 0.018ohm AC resistance along with a quarter of the inductance, although both cables have inductance and capacitance under control.  The only real difference I could find that may or not influence the sound is the resistance of the wires.

So, with the new interconnects I have had to attenuate the midrange/fundamentals/HF channels and the good sound seems to be back.  Early impressions at least.  This tuning has only been done by ear, but about 5dB more attenuation has been necessary in the upper channels, give or take, and I will have to find some time to pull out the microphone and measure the frequency response once more.

It seems as though the $6 interconnects really were broken, or at least they acted as a high pass filter for the sound, which means that I should re-visit the preamplifier comparisons to be fair to all contenders with the new interconnects.  What a pain.

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