Actually, you can survive just fine with the original Drawmer that the is based on, as the has proven itself in many studios worldwide and is part of the sound of many recording artists who love its character. The might be the start of a trend of "boutique" versions of well-known studio products that are offered in alternate versions to reflect the specifications and preferences of audio industry personalities. Like the , the is a dual-channel compressor with two mic preamps and a single, tube-based instrument auxiliary input. The unit occupies two rackspaces and is housed in a road-tough, steel cabinet. All rotary and toggle switches have a solid action, and the two VU meters are backlit by yellow LEDs--no bulbs to change. Bypass switching is done by silver contact relays for reliable operation.
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Update your browser to view this website correctly. Update my browser now. A short-term cure is to replace the damaged component; better still, fix the problem. Both have four tubes of the 12A? Clean, quiet DC power is supplied to the tubes from an LM voltage regulator rated at one amp. Four volt filaments in parallel consume milliamps mA of current. It was no surprise to find a normally green circuit board turned brown from heat. On the Jackson, 20V of raw DC fed the regulator, which is within tolerance if the load is a half-amp mA.
With no internal ventilation to allow the heat sink to do its job, the got hot enough to eventually discolor the board and even melt the solder before failing entirely. See Fig. Next, the Power formula determined the power in watts dissipated by the resistor; the wattage divided by 0. Remember, this is based on post -warm-up operation.
A trip to the local surplus store yielded two exquisite 2. Post-mod, none of the components was more than warm to the touch, and the amplifier is alive and well. Interestingly enough, the Drawmer had a fuse on the filament circuit to protect both the power transformer and the tubes should the regulator fail.
No amount of top panel ventilation holes would suffice, especially as the would likely be sandwiched between two pieces of gear.
The was eventually reborn as the — sonically tweaked and redesigned for greater reliability. Note: Tube-era designers concerned about heat literally thought outside of the box by mounting tubes and later transistors and heat sinks where ventilation was easiest to come by.
Even better than the single resistor added to the Jackson amp, the transistor current source allows the filaments to draw only mA, even during power-up.
The tubes would take longer to warm up, with the added benefit of extending life. Each transistor had its own piece of chassis real estate and was barely warm compared to the concentrated heat of the single regulator.
The current source has been around for a long time. One example goes back to the vacuum-tube era — the LA-2A output stage. I was first aware of it in the channel assignment section of MCI consoles, where driving all the LEDs in series required far less power than in parallel.
I also found it more recently in aftermarket replacement power supplies for tube microphones. In a vacuum tube, the filament boils electrons off the cathode. These negatively charged particles are attracted to the opposite charge — in this case, the plate, which becomes positive when a high voltage is applied.
Each amplifier within the dual triode has its own filament, and in the 12A? Back in the day, an AC voltage was applied to the filaments.
However, in many high-gain applications, our heightened sensitivity to noise requires clean, filtered DC, hence the use of regulators. Your browser is out-of-date!
DRAWMER 1960 Manuals
Update your browser to view this website correctly. Update my browser now. A short-term cure is to replace the damaged component; better still, fix the problem. Both have four tubes of the 12A?
Tech’s Files: Turning Down the Heat
This version is called the , and all of its modifications are courtesy of Fletcher and the guys at Mercenary Audio. I've been tracking with this device for a while now, and I love it, so I asked Fletcher how this all came to be. I came back from that session and there was a thread about Drawmer s on rec. Brad Lunde from TransAmerica Audio [who distribute Drawmer and other lines] called and made the suggestion that perhaps we could do better, and if not, shut the fuck up. So they sent us a unit, we evaluated the unit, we kept the DI from the original, it seemed benign enough, we kept the power transformer, it was useful, we kept the chassis, the meters and the tubes, the rest of it went in the trash. When we had a working prototype, we sent it over to Drawmer with the schematics of what we had done, and they built the first 'production prototype'. Says Fletcher, "The compressor goes into 'true stereo' as opposed to 'linkable dual mono'.
Started by tonebucket The Lab. Started by robinball The Lab. Started by brendandwyer The Lab. Toggle navigation. Register Login. Pages: [ 1 ] 2. Has anyone had any experience tech-ing one of these units?