SOWTER AUDIO TRANSFORMERS
EXCEPTIONAL PERFORMANCE MC PHONO CARTRIDGE TRANSFORMERS

High bandwidth step-up transformers (SUT)

We offer a range of exceptional step-up cartridge transformers (SUT) suitable for most cartridge impedances and a choice of ratio. Multi-section winding techniques are used to maximize bandwidth and transient response. All our cartridge transformers are constructed on Mumetal (76% Nickel) cores for minimal distortion and high bandwidth.. Our new "top of the range" type 1480 is "geometrically" balanced to provide virtualy perfectly phase split outputs for driving a push-pull amplifier. Connection is by colour coded flying leads (6 inches long). Octal base available for small extra charge. All types are contained in heavy gauge Mumetal screening can and may be used as they are or mounted in a plastic, wood or metal box as no other screening is required. TWO TRANSFORMERS are required for a stereo system

Moving Coil MC phono cartridge transformer SOWTER SUT 1740
SPECIFICATIONS (for more detail click the type number)
Quote TYPE
click for spec
 Application Ratio Cartridge Z (ohms) Bandwidth
+/- 0.5 dB		 Recommended
for

Can
Size
Buy 1480 Low
impedance 		1:10 1-15 5Hz -120KHz Z < 15 Ohms J
StockBuy 9570 1:10 1-100 5Hz-100KHz Z < 100 Ohms e
Buy 9990 1:20 1-15 5Hz-100KHz

<250 micro Volts

 e
Buy 1590 1:30 1-3 5Hz-60 kHz <250 micro Volts e
StockBuy 1990 Configurable
ratio 		1:10 or
1:20 		1-40 or
1-10		 5Hz-100KHz Z < 40 Ohms e
Buy 1090 Moving Magnet 1:2 ~1000 Ohms     e

CHOICE OF TRANSFORMER 

It is important to choose the right transformer for the cartridge you have. The choice depends on a combination of factors.

  1. The first step is to determine the actual impedance (resistance) of the cartridge.  As a guide if this is less than 40 ohms then choose a Low impedance transformer below.  If it is above 40 ohms then choose the High impedance transformer. High impedance cartridges tend to have a good output so the 12.5 ratio of type 9580 is gnerally adequate.
  2. Some cartridges have a low output (<250 microvolts) and we recommend a high ratio transformer (1:20). Obviously the ratio you need also depends on the gain of the amplifier as well as the cartridge output. The information below is only a guide. The only problem with using a 1:20 transformer with a high output cartridge is that the amplifier may need to be turned down very low. 1990 is the same transformer as 9570 and 9990 but has all the connections brought out so the twin primary windings can be connected in series or parallel to set the ratio. This is offered at a small extra charge so the customer can experiment.
  3. For the ultimate listening experience 1480 can be used with any low impedance (<15 Ohms) cartridge. This transformer is intended to be used with a normal unbalanced or push-pull amplifier without a separate phase slitter. An RC (Zobel) network is not required for this transformer.

CARTRIDGE LOADING

In general Moving Coil cartridges work best when connected to a load impedance at least ten times the cartridge impedance. Some cartridges need to be damped to prevent high frequency resonance of the moving parts and it is a good idea to experiment with various loads to see if this improves the sound. We recommend using a resistor across the secondary of the transformer. Note that the reflected load (as seen by the cartridge) will be the load resistor times the ratio squared. A reflected load of between 5 and 20 times the cartridge impedance might be suitable. So for example if the cartridge impedance is 5 ohms and you want to try a damping load of 50 Ohms and you are using a transformer with a ratio of 1:20, the secondary resistor should be 50 x 20 squared = 20k Ohms. With a ratio of 1:10 the resistor would be 50 x 10 squared = 5k Ohms. With a 1:30 ratio and a 10 Ohm cartridge the load should be not less than 90K Ohms. The minimum load value in the table below is also a guide to setting the load but it is recommended to carry out listening tests.

RECOMMENDED TRANSFORMERS BY CARTRIDGE
Manufacturer Model Z(Ohms) Min Load (Ohms) Output (uV) Recommended SUT
1480 9570 9990 1990 1090
Audio Technica AT-OC9ML/II (2)? 20 500 o o o o  
Benz Micro Ref 2 Silver 8.5 100 300 o o o o  
Benz Micro Glider L2 12 120 300 o o      
Benz Micro L2 13 100 300 o o      
Benz Micro MC Gold 20 200 400   o      
Benz Micro Glider M2 24 200 800   o      
Benz Micro M2 24 200 800   o      
Benz Micro LP Ebony 38 500 280   o      
Benz Micro Ruby 2 45 400 450   o      
Benz Micro Ruby 3 40 400 340   o      
Benz Micro Ruby H 85 1000 800   o      
Benz Micro Glider H2 90 1000 2500   o      
Benz Micro H2 90 1000 2500   o      
Benz Micro MC20E 110 47000 2200   o      
Benz Micro MC Silver 120 1000 2000          
Benz Micro Ace L 12 200 400 o o      
Bloom H R50 8 100 480 o o o o  
Cardas Heart 40 400 300   o      
Cardas Myrtle 45 500 380   o      
Clear Audio Victory-Gold 9 90 200 o o o o  
Clear Audio Accurate 50 500 600   o      
Clear Audio Discovery 50 500 500   o      
Clear Audio Gamma 50 500 500   o      
Clear Audio Insider Gold 50 500 600   o      
Clear Audio Insider Reference Wood 50 500 700   o      
Clear Audio Sigma Wood 50 500 600   o      
Clear Audio Signature 50 500 500   o      
Clear Audio Victory H 50 500 600   o      
Denon DL-103 40 100 300   o      
Denon DL-103R 14 100 300 o o      
Denon DL-301 Mk2 33 330 400   o      
Denon DL-304 40 100 180   o      
Denon DL-110 160 47000 1600   o      
Denon DL-S1 40 100 150   o      
Denon DL-160 160 47000 1600   o      
Dynavector DV XX-1L 3 30 250 o o o o  
Dynavector Te Kaitori 4 100 250 o o o o  
Dynavector DV17D2 MkII Karat 38 100 230   o      
Dynavector DV23RS MkII 10 100 150 o o o o  
Fuji ZYX R-100 4 100 250 o o o o  
Goldring Elite 8 100 500 o o o o  
Grado Master 2 20 500 o o o o  
Grado Platinum 2 20 500 o o o o
Grado Reference 2 20 500 o o o o  
Grado Sonata 2 20 500 o o o o  
Immutable Music Transfiguration Spirit 10 100 400 o o o o  
Koetsu Platinum 5 50 250 o o o o  
Koetsu Black 5 30 400 o o o o  
Koetsu Rosewood 5 100 600 o o o o  
Lynn Troika 5 100-470 200 o o o o  
Lyra Titan i 5.5 100 500   o o o
Lyra Parnassus 2 100 250 o o o o  
Lyra Helikon Mono 3 100 250 o o o o  
Lyra Lydian Beta 4 100 500 o o o o
Miyabi Alnico 4 40 250 o o o o  
Ortofon SPU Meister A 1.5 10 300 o o o o  
Ortofon SPU Meister GM 1.5 10 300 o o o o  
Ortofon SPU Meister Silver A 1.5 10 300 o o o o  
Ortofon SPU Meister Silver GM 1.5 10 300 o o o o  
Ortofon SPU Classic A 2 10 100 o o o o  
Ortofon SPU Classic A E 2 10 200 o o o o  
Ortofon SPU Classic GM 2 10 200 o o o o  
Ortofon SPU Classic GM E 2 10 200 o o o o  
Ortofon SPU Reference A 3 10 200 o o o o  
Ortofon SPU Reference GM 3 10 200 o o o o  
Ortofon SPU 90 Anniversary 2 10-50 300 o o o o  
Ortofon Kontrapunkt a 5 50 470 o o o o  
Ortofon Kontrapunkt b 5 50 450 o o o o  
Ortofon MC 10 Super MkII 5 10 200 o o o o  
Ortofon MC 10 Supreme 5 20 500 o o o o  
Ortofon MC 20 Super MkII 5 10 200 o o o o  
Ortofon MC 20 Supreme 5 20 500 o o o o  
Ortofon MC 2000 MkII 5 20 125 o o o o  
Ortofon MC 30 Super MkII 5 10 200 o o o o  
Ortofon MC 30 Supreme 5 20 500 o o o o  
Ortofon MC 3000 MkII 5 10 125 o o o o  
Ortofon MC Jubilee 5 10 340 o o o o  
Ortofon MC 10 Super 6 10 300 o o o o  
Ortofon MC 25 E 6 20 500 o o o o  
Ortofon MC 25 E 6 20 500 o o o o  
Ortofon MC 25 FL 6 20 500 o o o o  
Ortofon MC 25 FL 6 20 500 o o o o  
Ortofon MC 5000 6 20 140 o o o o  
Ortofon MC 7500 6 70 130 o o o o  
Ortofon MC Rohmann 6 10 250 o o o o  
Ortofon Rohmann 6 100 250 o o o o  
Ortofon SPU Royal A 6 100 200 o o o o  
Ortofon Rondo Red 6 100 500 o o o o  
Ortofon SPU Royal GM 6 100 200 o o o o  
Ortofon SPU Royal N 6 100 200 o o o o  
Ortofon MC 15 Super MkII 7 20 340 o o o o  
Ortofon Tango 10 >20 500 o o o o  
Ortofon Samba 6 >10 300 o o o o  
Ortofon Salsa 7 >20 380 o o o o  
Pickering XLZ-7500-S-mk2 unknown
5 Ohms?		 load 50 to 250 330 o o o o  
Shelter 901 5 100 1400 o o o o  
Shelter 501 II 10 100 400 o o o o  
Sumiko Pearl MM MM           o
Sure V15VxMR MM MM 3 mV         o
Van den Hul Black Beauty a 16 >500 500   o      
Van den Hul Black Beauty b 41 47k       o    
Van den Hul Black Beauty c 96 47k       o    
Yamaha MC11 30 300 350   o