input level at 20 Hz
|50 dB||2 dB||85 H||1:1||310
|Buy||1035||10k||50 dB||2 dB||+6 dB||5x0.5 dB|
|Buy||9395||10k||50 dB||2 dB||+6/12 dB|
|Buy||9985||10k||50 dB||2 dB||5x0.5 dB|
|Buy||9336||10k||42 dB||3 dB|
|Buy||9337||10k||28 dB||2 dB|
|Buy||9338||10k||6 dB||0.5 dB|
|Buy||9339||10k||24 dB||1 db|
|40 dB||10 dB||120 H||1:1||e|
|Buy||9155||10k||10 dB||2 dB||120 H||1:1||e|
FEATURES Attenuator transformers used in conjunction with a multi position switch provide a high performance volume control function. Sowter proprietary winding technique ensures 100 kHz bandwidth at all switch positions. The transformer action of these attenuators ensures the loading circuit sees a low driving impedance regardless of the switch position. This ensures the maximum bandwidth potential and minimum distortion of the whole circuit can be realised at all gain settings. As the attenuation is related to the number of turns at the winding tap, the attenuation is exactly matched between stereo channels. A range of transformers is available for different total attenuation and step size. The Mumetal core ensures very low Total Harmonic Distortion. High input impedance to minimise loading on the driving circuit. Mumetal can to ensure minimal hum pick-up. Colour coded leads. The transformers provide good dc isolation and can be used in balanced or unbalanced circuits.
GAIN TAPS Type 9395 is the same as type 9335 except taps are provided on the primary. These will provide a gain of 0 dB, +6 dB and +12 dB. Suitable for driving from 2k ohms or less source when +6 dB tap is used and 600 ohms or less when +12 dB tap is used. The overall bandwidth is is reduced when these taps are used. Typically +/- 3 dB from 10 to 50 kHz for either primary tap. The performance when the 0 dB connection is used is identical to 9335.
BALANCE CONTROL Types 1035 and 9985 have 5 x 0.5 dB primary taps which can be used for a stereo balance control providing up to +/- 2 dB difference between channels. 1035 has balance taps which include a maximum of 6 dB gain. The balance control can be wired so that with a single two wafer switch and two attenuators gain can be added in 0.5 dB steps to the left or right channel. See schematic.
LOW COST COARSE AND FINE ATTENUATORS Types 9150 and 9155 have been redesigned to bring the performance to be comparable with the other types. They can be used separately or in cascade for a coarse and fine control.
APPLICATION These transformers should be driven from a source impedance as low as possible but will work well with a source up to 10k ohms. Where necessary a blocking capacitor should be used to ensure no dc is applied to either winding. The secondary load can be any value the higher the better. A Zobel network is not required on types 9335 to 9339 to damp high frequency resonances which are non-existent. These transformers provide isolation and may be used for balanced to unbalanced conversion or vice versa. It is recommended to use a separate transformer in a high noise environment or if long cables are to be used. If a ratio change, high common mode rejection is required or dc in either winding is required we will be happy to recommend a suitable transformer to be used in concert with 9335. Depending on the circuit configuration this may be possible with minimal loss of performance.
SWITCHES We recommend switches from Shallco. The suggested type number is 214-FB-26 for 26 position attenuators and type number 123-DB-9 for the balance control. Shallco prices are in US Dollars and may be ordered using a credit card. Our French Distributor MADOTEC can supply Shallco rotary switches up to 48 positions ( 26 is enough for any attenuator from the 93xx range ). Prices are on the MADOTEC webpage. We recommend "non-shorting" (break before make) switches.
We have worked with one of our customers, Swan Song Audio, to develop an alternative to the traditional point to point wiring found in nearly all Transformer Volume Controls. This kit greatly reduces assembly time and failure points by replacing the extensive wiring with a PCB and high end relays. The builder is required to:
To build this kit, start by purchasing any of the 24 step attenuators on this page. Next, go to this link, search for TVC, and purchase the kit. Total assembly time is 3 - 4 hours.
If you have any specific questions concerning the kit, you can contact firstname.lastname@example.org
|9335 LEAD OUT COLOURS|