UralTone REDD .47 1 or 2-channel all tube mic pre kit

The UralTone REDD.47 rack is a 1 or 2 channel building kit clone of the REDD.47 front stage of the REDD.51 recording desk (1964-1968) from Abbey Road studios.

The device is built in a 19" rack case that can accommodate 1-2 identical channels.

Specs:

• 1 or 2 channel REDD.47 clone
• EF86 and ECC88 (E88CC, 6922, 6DJ8) tubes
• Lundahl input and output transformers (option)
• Connections: mic in xlr, line out xlr, power in 5-pin xlr
• Controls: 6-step gain + fine gain, 3-step output attenuator, Phantom, input pad, 6 step high pass filter
• The basic package includes the components for one-channel (tubes included) with a power supply without the audio transformers. Second channel components (tubes included), Lundahl transformers and a 19" aluminum case can be added for an extra charge.
• However, it does NOT include potentiometer knobs. You can get the ones you like from this link

The UralTone REDD.47 circuit is simple. After the input, there is a transformer that raises the signal and impedance level to suit the tube. The first amplification stage is implemented with the EF86 pentode designed by Mullard and the output with the E88CC double triode, both triodes connected in parallel. Before the output, there is a transformer that drops the output impedance. A feedback signal is sent from the E88CC anode to the EF86 cathode. The strength of the feedback can be adjusted with the gain rotary switch and the fine gain pot.

There's some options how to build the kit. The most easiest option is pick Adam Hall rack enclosure with double front panel kit. Adam Hall enclosure is made out od steel and this makes it cheaper option. Hammond enclosre requires tools to make holes for XLR- and IEC connectors on back. By the quality Hammond is superior, it's sturdy and the finishing looks amazing. Options are:

• One or two parts kits, mono / stereo.
• Lundahl transformers or without.
• Hammond or Adam Hall -rack enclosure or no eclosure with various different panel options:
  • 2U stereo rack front panel for Hammond enclosure. Requires hand drill, stepped drill or set of bits up to 24mm and file for square cutout for IEC connector.
  • 2U stereo rack front panel + rear panel for Adam Hall enclosuree. Requires hand drill, stepped drill bit or set of bit up to 12mm.
  • 2U stereo rack front panel (2x) + rear panel for Adam Hall enclosuree. Requires hand drill, stepped drill bit or set of bits of 3mm and 4mm. Two front panels are used as stacked.
  • No panels. Basic parts kit contais small single channel front panel. Requires drilling holes.

Very high quality components

The components for the construction series have been selected specifically based on quality.

Signal transformers are very critical parts in studio equipment.

The 19" rack version has larger Swedish Lundahl transformers, which are considered the best audio transformers available. The construction kit transformers are an option, which means that the microphone stage can also be built with other audio transformers. However, we have not tested other models, so we cannot provide technical support for other transformers.

The Sprague Vitamin Q NOS USA capacitors in the signal path represent perhaps the best audio capacitors ever made. These were originally made for the US Army without sparing any expense. It's hard to even imagine what a capacitor like this would cost if manufactured today.

High-quality audio tubes are included. The EF86 is the most critical tube in this circuit and it can be upgraded to a more expensive NOS version if desired. Of course, the output tube is also important and you can try any ECC88, E88CC, 6922, 6DJ8 and also Russian 6N1P or 6N23P tubes.

What does the kit include?

The basic package includes the components for one-channel with the power supply but without audio transformers. The basic package also includes front panels and tubes for one channel. The second channel components, Lundahl transformers and 19" aluminum case are available for an extra charge. The case is undrilled, but it is easy to drill holes in the Hammond rack case with a step drill.

The price also includes instructions and unlimited technical support.

Instructions

The build kit comes with a layout picture, a schematic and a parts list, which makes it easy to assemble the device. This article contains pictures and tips for building the device (english version coming soon). 

Tools

It is important to use high-quality tin with 3-4% silver. For example, this model.

The soldering station must be of at least reasonable quality and the temperature suitable for lead-free tin (approx. 375C often works). We have collected recommended tools here in the hobbyist price category:
A beginner's tool kit

It is important to note that the old soldering irons intended for lead-free tin will not work if the temperature cannot be raised high enough.

Technical support

UralTone building kits always include unlimited technical support via e-mail. The store does not have the usual technical support staff and it is difficult to help over the phone, so our support only works via e-mail.

How long does it take to assemble the kit?

An experienced person can build up a set in a day, a beginner can take 2-3 days.

Who is this building kit suitable for?

For everyone who appreciates warm and musical sound quality. For those of us who like vintage equipment and the uncompromising sound quality of a 1960s Abbey Road studio.

It is also for those who want the quality, durability (and thus also ecology) of boutique devices, but whose budget does not support the high-quality boutique class of ready-made devices. Doing it yourself saves a lot when it comes to studio equipment.

What value do you get for your money?

Carefully assembled from our building kits, this preamp matches the quality of the most expensive boutique equipment. The parts are top class and the devices are carefully designed. The price also includes unlimited technical support either by email or through our support website. With us, the customer is not left alone!