Don't worry, folks! I may have recently moved to the very edge of the Green River Gorge, but I have not yet fallen off the face of the Earth. I have so much new stuff that I have been brewing that I just can't WAIT to share it with all of you. New Akai / Roberts, Magnecord, Tape Delay (Ampro and Webcor) designs are simmering while I close out my waiting list for 2012. Look for some BIG moves come January! Pictures? Well, I do have pictures of my new place and my new tractor, er... truck.
Tuesday, November 27, 2012
Wednesday, November 7, 2012
I just bought this lovely mono, tube powered reel to reel off of an auction site. I saw a video on youtube where someone made a crude version of a tape delay with a similar deck. For my version I have some more detailed and involved plans to completely transform this unit into a full fledged tape delay with adjustable tape speed, microphone input (with transformer), preamp, simple mixer, and power section that drives a speaker. So, it will be a colored microphone preamp and low watt guitar amp in addition to being a tape delay! I am even working out how to modify the original little crystal mic to fit on a standard mic stand clip by adding a handle. I have two of these Webcor mics headed my way, so I may just wire them in series and or parallel as some kind of double-element mic. Of course this would be a very colored mic, but so is the preamp! Here is the original schematic.
Thanks to Dr. Zee of http://www.mzenertainment.com for scanning this schematic. Be sure to check out his site. If you like what I am doing here on this blog you'll love the amazing projects he has built for his own studio. I am really impressed and hope to get XFMR to that point soon.
Looking over this schematic, this unit is ripe for modification. All the tubes are driven by the power transformer, so no weird AC doubling circuit for power tube B+ like found in the Wollensak T-1500 units. The motor is an AC type and not a good candidate for adjustable speed, so right there I will have to start looking for a DC motor to replace it. My first order of business is to examine the schematics of dedicated tube tape delays like the Gibson Echoplex EP1 and EP2 to see what parts of this circuit I can toss. First thing to go is all the switching. The modified unit will have two modes: tape spinning as a delay and tape not spinning as a straight up amplifier. I will have a dedicated toggle switch that cuts the motor on and off and another toggle with a footswitch in parallel that mutes the delay circuit.
In my plans I would like to have just one extra playback head. No need for multitaps as that just gets more complicated. For controls I will keep it simple: preamp gain, feedback amount, dry level, wet level and of course a tape speed control. There will also be a 1/4" footswitch jack to round out the controls. I/O will include an XLR input with pad and phase switch, a Hi-Z input, speaker-level 8 ohm output, and a line level output. It has a built-in speaker, but I will have a switch that switches this to a dummy load when necessary. The reason for the XLR input is that this unit will be made for vocals in addition to instruments, so I figured if I remove the counting mechanism I will have plenty of room on the face for the female XLR jack.
Here are some additional pictures of the donor unit and a few other parts units that I bought mostly for their Webcor heads, but I am sure I will find other parts to vulture for this and the next unit. I am planning on building two of these: one for my good friend and patron Damiam Asker and one for the XFMR studio collection.
Webcor Regent model EP2006-1A:
This model is very similar to my main EP2001-1C unit and will make a fantastic parts donor.
Webcor Regent model GP2910-1
This last model has vastly different guts, thought it looks similar from the outside. It should still yield many great parts for this pair of mods.