KM56, SM69, Watkins Amplifiers

Author: matthew; Published: Nov 10, 2008; Category: Amplifiers, Microphones; Tags: , , , ; 2 Comments

Spent the morning helping set up for the new session. Balanced the Genelec near-field monitor levels to the NS-10s. Oriented the visiting engineer.

Problem – One of the matched KM56 mics and one side of the stereo SM69 have the delightful sounds of cracklin’ potatoes after being on for an hour.

Solution – I left the mics powered up on the bench for more than 24 hours. none of them show any evidence of problems. This is irritating. I applied various stress positions to no avail. The capsules seem to seat properly and the cables seem intact. I do not know what mic cable was used for either microphone when the initial problems presented.

Problem – The newly acquired Watkins amps sound good but are too quiet.

Solution – Upon examination it turns out that both amps are set up to run only on British voltages and when I apply 220 volts both amps sound great. I discussed the situation with the studio manager and she preferred that I change the power transformers in the amps rather than run them from external transformers. I ordered transformers from Weber.

Thermionic Culture Vulture

Author: matthew; Published: Nov 8, 2008; Category: Outboard Gear; Tags: , , ; No Comments

Problem – The Thermionic Culture Vulture isn’t passing signal on the right side.

Solution – This thing eats an EF86 tube about every seven months. I replaced the one on the right with a known good one and the piece soldiers on. I tried the bad tube on the left and it made the left bad. Troubleshooting! The tube is operating within spec and there aren’t any physical problems I can see that would cause it to fail.

More Neve 8068

Author: matthew; Published: Nov 6, 2008; Category: Neve Infirmities; Tags: , , , ; No Comments

Troubleshooting! This made it work.

Troubleshooting! This made it work.

a hardwired jumper. top washer of washer sandwich is visible on the lower lug.

a hardwired jumper. top washer of washer sandwich is visible on the lower lug.

Problem – Channel 5′s VU meter isn’t responding.

Solution – Upon troubleshooting the channel it became clear that the washer sandwich I mentioned yesterday was the issue. This time cleaning the washers didn’t solve the problem, so i installed a soldered jumper. This is one of those trade-offs sacrificing easy modularity in favor of reliability.

Problem – Uptown automation isn’t grouping properly. The computer controlling our uptown automation system thinks the after-aftermarket mute boards are attached to different channels. Also, the motors are behaving strangely.

An incorrect but simple solution – Swapping ribbons. The channels go left-to-right for the motors and right-to-left for the mutes. Intuitive! This works, but some of the ribbon cables aren’t long enough to reach. Also, this leads to serious spaghetti-cabling under the faders. I am now seeking a software solution. There’s interaction between soft switches and the DIP switches on the fader driver cards.

Solution – RTFM. again. Switching few DIP switches and a little autoexec.bat editing along with some fine detective work and the faders are flying and properly associated by the software with the correct after-after-aftermarket mute card. I wish I could go back in time and give these guys a copy of autocad or a bag of holding: between all the connectors and ribbon cable it’s stress/future failure city under the faders.

Neve 8068

Author: matthew; Published: Nov 6, 2008; Category: Neve Infirmities; Tags: , , , ; No Comments

Got a late start. listened to Tyler’s CD and Danny/Tyler’s attempt to pare it down to a tight 40 minutes in order to cut some audiophile-quality vinyl. Should be good.

Problem – Neve 8068 left front channel has drifted up a few dB and now is 1 or 2dB high relative to the right front when a signal is assigned down the middle. The rear left meter reads nothing and the rear right meter is always pegged in spite of the signals being more or less the same when a signal is applied equally to both.

Solution – Busted out the NTI meter and tweezed the appropriate routing modules. fixed errant rear VU meters with deoxit and a tweaker. There’s a washer sandwich that acts as a physical and electrical connection between the meter cards and the meters; it often gets dirty and turns into a spontaneous high-impedance connection. It seems to me that a connection should be either structural or electrical, not both. Dual connections like that are a frequent failure point in everything I work on. Once the meters were moving properly I adjusted all four channels so zero is zero is zero on the stereo buss, front and rear, the meters and the fishfinder.