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perhaps the very best “wire winder” ever, his dad Ed Reichenbach. Ed owned
and operated Reichenbach Transformer company during the golden age of Los
Angeles studios. He made transformers for all applications, including for the
studios. One of his outside sales guys was Dean Jensen. Dean specialized in
studio customers and audio manufactures and helped design transformers to fit
their demanding needs.  Dean was a sales engineer, Ed was the designer and
manufacturer.  Later, Jensen formed his own sales company and named these
“Jensen” transformers gaining (at that time) a high reputation for making 
perhaps the best sounding transformers of the day.  But Dean’s offices were
always located inside Ed’s transformer factory and Ed actually made these 
classic Jensen transformers!  Unfortunately, when Dean died, his business went
into a bankruptcy proceeding which resulted in the Jensen brand name being
sold to a former employee, and Ed simply retired and sold the Richenbach 
factory.  Soon after that, Tom started his own transformer business under the
direction of his dad.  Frankly spoken, we’ve sampled all the best transformers
at every price point made today, and Tom’s transformers out perform them all
every time... so we stayed with Tom on the VELO-8 project and it really paid
off.  Here’s what Tom and GT came up with in this latest collaboration.

The VELO-8 transformer uses pure nickel core laminates with multi-tapped
output windings that allow the level to be switched between 75 Ohms (most
detail) and 300 Ohms (most signal strength).  We also added a High Pass filter
for both windings so there are four switched selections located on the lower
rear side of VELO-8’s body. The highest signal level is achieved in the 300
Ohm position. The 75 Ohm position will have less output but also will be 
obviously “altered” and so will provide more natural detailed results, but it will
require more preamplification that may not be available on some mixers (but
perfect for ViPRE and SuPRE either way!). Also, the low frequency roll off can
be useful as ribbons really produce a lot of information in this the ultra low
bandwidth area which could make a voice, drum or guitar sound too boomy.

4. The Design:

Actually the size and shape of the ribbon, placement of the 

ribbon in the magnetic field, and quality of the coupling transformer which
boosts the impedance of the ribbon’s output are the most influential 
components to the end result, but without a coherent design to combine them
all could be lost! Our VELO-8 design is an original (not another “Elvis 
impersonator”, please!); it has higher than normal output levels as a result of
the increased magnetic field created by our custom formed dual “roof top”
magnets and special designed Cinemag transformer. It offers a dual contrasting
ribbon placement design that produces different, but desirable, sounds from
both the front and rear of the mic. Now, the engineer has two different 
sounding sides to choose from; the back side is less bright than the front side.

7

VELO-8 REFERENCE MANUAL

Summary of Contents for VELO-8

Page 1: ... Groove Tubes LLC All Rights Reserved ...

Page 2: ...Groove Tubes Velocity Ribbon Microphone Reference Manual VELO 8 ...

Page 3: ...For the latest information on your Groove Tubes product visit our web site at www groovetubes com Or call us toll free at 800 459 5687 1 VELO 8 REFERENCE MANUAL ...

Page 4: ...essure levels like those generated by a closely miked strong vocalist or a bass drum on axis can easily rip the thin aluminum ribbon element resulting in a costly and time consuming re ribboning repair adventure Replacing the torn ribbon is a delicate maneuver and only possible if performed by a highly experienced mic tech or a factory repair department Unfortunately both in the early days and tod...

Page 5: ...too weak to effectively boost the level to the strength of the more common condenser mic Our ViPRE and SuPRE mic preamps were specifically designed to load the ribbon with a matching balanced transformer winding of 300 Ohms instead of the industry standard of 2 000 Ohms or higher These preamps also amplify over 70dB so this feature set was specifically intended to allow ViPRE and SuPRE to address ...

Page 6: ... or not crimped also contributes to the end audio result as well This is why so few vintage RCA mics today even of the same models and era sound exactly alike But some common truths are found the larger the ribbon element the more output level it generated i e the RCA 44 and the thinness contributed to more or less detail as well as more or less reliability For example a thicker ribbon meant more ...

Page 7: ...magnetics both yesterday and today have been made from off shelf square bars placed in a metal conductor But instead of using commonly available off shelf magnets we designed and custom cast a totally new roof top shaped magnet that concentrates the magnetic field on the edge of the ribbon and increases signal output We also used the highest quality aerospace Neodymium material that costs 20 times...

Page 8: ... transformer can add unpleasant distortion and frequency loss and or shift so we don t recommend that But it s interesting that many customers of lower cost Chinese ribbon mics are now retrofitting them a higher quality Western made output transformer made in Europe or here in the States that easily cost twice what they spent on the mic There is a noticeable improvement of course as less degrading...

Page 9: ... tapped output windings that allow the level to be switched between 75 Ohms most detail and 300 Ohms most signal strength We also added a High Pass filter for both windings so there are four switched selections located on the lower rear side of VELO 8 s body The highest signal level is achieved in the 300 Ohm position The 75 Ohm position will have less output but also will be obviously altered and...

Page 10: ... ribbon is mounted and precisely pre tensioned on a unique circuit board material so it can be replaced in minutes the process involves removing just four screws on the chassis and another four screws on the motor with a simple procedure that takes about 10 minutes start to finish So How To Notice when you unpack your VELO 8 there will be a small pre tensioned ribbon assembly mounted on a small PC...

Page 11: ...her side of the XLR connector CAUTION Be sure to keep all screws a good distance from the open mic chassis as VELO 8 s magnets are extremely powerful and so can attract metal objects in close proximity and at a great velocity possibly damaging the ribbon element 2b Carefully slide off the bottom portion of the chassis shell downward taking care not to damage the impedance and roll off switch 2c Ca...

Page 12: ...lignment when the screws are removed This sounds hard but it s not and you will feel so accomplished when this is finally over 2g Remove the top screws first and move these away from the work area Keep consistent pressure on the PCB and remove the bottom screws 2h Slowly and shall we say carefully lift the PCB up and away from the motor assembly Now you are ready to change out with the new PCB rib...

Page 13: ...o any strong breath or touching it against anything could rip it to shreds well maybe not shreds but it wouldn t be a happy moment if you inadvertent ly broke it at this delicate and late stage in the game 3b Hold the PCB against the motor chassis with one hand ensuring that the holes on the PCB are lined up with the holes on the motor assembly and care fully are you getting tired of this word yet...

Page 14: ... it all together That s All Now let your girlfriend finish tracking that Joplin cover But this time use a GT Pop Filter VELO 8 Specifications Microphone Type Velocity Ribbon Operating Principle Electro dynamic pressure gradient Polar Pattern Bi directional Fig 8 Generating Element 2 5 micron corrugated aluminum ribbon Ribbon Dimension 0 10 x 2 10 2 50mm x 53 14mm Magnetics Custom Formed Rare Earth...

Page 15: ...ess Applications GT50 1 1 x 3 microns with Disk Resonator Class A FET Cardioid Top A classic fixed position cardioid mic with warm Class A FET electronics Good for male and vocals choirs pianos ochestral micing and other applications Model Diaphragm Electronics Patterns Address Applications GT60 1 1 x 3 microns with Disk Resonator Class A Tube Cardioid Top All sources will benefit from its tube wa...

Page 16: ...entic VU metering SuPRE Stereo tube mic and instrument preamplifier Two channel stereo microphone and instrument preamplifier Variable transformer impedance settings on each channel 72dB of gain on each channel The Brick Tube preamplifier line driver and DI Tube mic instrument pre for the studio and stage Can run 1000 feet and more without the losses of simple direct boxes High quality sound Sturd...

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