Penny & Giles Rotary Faders for Professional Application

Penny & Giles offers two families of high-quality stepless rotary attenuators for demanding audio applications.  These products feature the same durable co-molded resistive elements and wire spring contact fingers that make the P&G straight-line faders very popular.  The mechanical structure is made from precision-machined metal parts, not stamped or cast metal, and the unit is sealed to exclude dust.

Similarities and Differences

The RF11 family consists of mono and stereo versions that are 1 1/16” (27mm) in diameter.  The molded resistive elements include embedded stranded wire leads.

The RF15 family consists of mono, stereo, 3, 4, 6 and 8-channel versions in a larger 1.44” (36.5mm) body.  Connection is via metal turret terminals that stick out radially from the body.  A cue switch is available as an extra-cost option with the RF15.

Although both models are available with either linear or log tapers, the log tapers or ‘laws’ of the two series are different.  The smaller RF11 is down about 30 dB at mid-rotation, compared to only 20 dB of attenuation for the RF15.  This means that there is more resolution on the bigger unit over the first half of the rotation, which may be useful in precisely setting the output level. 

The following attenuation curves of measured samples illustrate these differences.  (These curves were generated at MANCO by driving the pots with a 1 RPM motor, using an Audio Precision System One to graph the output.  The System One didn’t like measuring a signal that is changing continuously during the measurement, which caused some intermediate points to be missed.)

RF11 (lower trace) and RF15 (upper trace) Attenuation

Horizontal scale in seconds – 6 degrees of rotation per second

In addition to the shape of these attenuation curves, the user is usually very concerned about the level matching between the channels.  Specification for absolute accuracy, stereo gain matching and kill are good for the RF11, but even better on the RF15:

	Accuracy	Matching relative to Track 1	Kill
RF11	+/- 2 dB (0-20dB)	+/-1 dB (0-40dB)	85dB
	+/- 4 dB (21-60dB)	+/-2 dB (41-60dB)
RF15	+/- 2 dB (0-60dB)	+/-1 dB (0-60dB)	90dB
		(+/-0.5dB to -40dB available at extra cost)

These RF15 specifications compare favorably with the popular PGF 3222 linear stereo fader used as the master fader on many consoles, which has a matching specification of +/- 1 dB (0-40dB).

Larger size is the primary reason for the more stringent performance specifications of the RF15.  For audio taper versions, the log audio taper is achieved by adding several shunting legs to ground at various points along the main resistive track to provide extra attenuation at the beginning of the attenuation curve.  (Without this loading, the attenuation would be only 6 dB half way through the rotation.)  The extra space of the RF15 is utilized to fit larger trimming pads/legs that can be trimmed more precisely for tighter accuracy and matching. 

Although linear taper versions don’t require shunting legs, the extra space is utilized to provide extra width on the resistive track.  Since the width of this track is physically trimmed away to achieve the desired linearity, starting with a wider, longer track allows tighter calibration.

Larger size also provides better kill or cut-off at full attenuation. The larger size of the RF15 allows placing more silver around the termination area, reducing electrical resistance between contact and the output terminal.

The larger RF15 also allows several Cue switch and detent options, as well as nominal resistances as low as 1K Ohm.

The standard resistance for both families is 10K ohms, but other resistances are available at extra charge.

See also:	RF11 data sheet:  http://www.pennyandgiles.com/dsp_product_info.cfm?productid=41
	RF15 data sheet:  http://www.pennyandgiles.com/dsp_product_info.cfm?productid=42

Special Pricing for NAB ‘03

As a special limited-time promotion of these products, MANCO, in cooperation with Penny & Giles, is offering the following mono and stereo versions of both series at a considerable reduction from the old pricing.  The resulting price savings of 30 – 40% make these precision attenuators even more attractive for demanding application such as monitor level controls on consoles and digital workstations.  In addition, MANCO is now able to offer these units in single quantities, rather than the previous minimum of 2 units.

	Mono	Stereo
RF11/x/C/A  5Kohm	$90 (was $151)	$120 (was $210)
RF15/x/D/A 10Kohm	$160 (was $252)	$250 (was $357)
(x=1 for mono, x=2 for stereo)

For orders and additional information, contact:

Dale Manquen at MANCO	(805) 529-2496
dmanquen@msn.com	1694 Calle Zocalo
www.manquen.net	Thousand Oaks, CA 91360