This is a very basic question: I have bought a pair of Sowter SUTs and I am about to wire them into my cart to amplifier path.
The Sowter site simply says to connect the white and yellow leads to the cart and the pink and mauve ones to the amplifier, without mentioning which lead matches which and which goes to the signal vs. ground path.
I guess I can find the in/out matching by tetsing which wires are connected, but how about the ground/signal? Does it matter at all?
Thanks.
gm
The Sowter site simply says to connect the white and yellow leads to the cart and the pink and mauve ones to the amplifier, without mentioning which lead matches which and which goes to the signal vs. ground path.
I guess I can find the in/out matching by tetsing which wires are connected, but how about the ground/signal? Does it matter at all?
Thanks.
gm
Seems to be a balanced transformer in and out, so the leads are interchangeable (except for polarity).
You might email them and ask to be sure about the polarity. Wire both channels the same way regardless.
Usually the lighter color is positive, so try
white = + in
yellow = - in
pink = + out
mauve = - out
You might email them and ask to be sure about the polarity. Wire both channels the same way regardless.
Usually the lighter color is positive, so try
white = + in
yellow = - in
pink = + out
mauve = - out
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Thanks. I will email Sowter just for confirmation's sake. Obviously it's my first experience with SUTs.
The transformer is a 9570 by the way: SOWTER TYPE 9570 phono cartridge transformer
The transformer is a 9570 by the way: SOWTER TYPE 9570 phono cartridge transformer
Thanks, good I turned to this forum because Sowter hasn't replied yet (they must be slammed with orders).
I have made all the connections as indicated but listening to my cartridge (Denon DL-103) the signal is barely audible, as if there no amplification at all came from the SUT. My only other cart is a MM so I can't make a comparison, but I did play the DL-103 without SUT and I recall that the level was similar.
The only somewhat unusual part of my layout is that I'm wiring the transformers directly to the arm wires, inside the turntable chassis. I double-checked the wiring and all seems correct, see image: hot L (white) and R (red) to white SUT wires, ground L (blue) and R (green) to yellow; pink to center pins of RCA jacks; mauve to ground pins.
Could something else be wrong? If it's a bad soldering I assume it should be equally bad in both channels because the levels are equally low. I can't test cart to primary because the connections are sealed as you can see (unless I cut the wires and restart).
I have made all the connections as indicated but listening to my cartridge (Denon DL-103) the signal is barely audible, as if there no amplification at all came from the SUT. My only other cart is a MM so I can't make a comparison, but I did play the DL-103 without SUT and I recall that the level was similar.
The only somewhat unusual part of my layout is that I'm wiring the transformers directly to the arm wires, inside the turntable chassis. I double-checked the wiring and all seems correct, see image: hot L (white) and R (red) to white SUT wires, ground L (blue) and R (green) to yellow; pink to center pins of RCA jacks; mauve to ground pins.
Could something else be wrong? If it's a bad soldering I assume it should be equally bad in both channels because the levels are equally low. I can't test cart to primary because the connections are sealed as you can see (unless I cut the wires and restart).
Attachments
There is a drawing on Sowter's website that confirms it all.
SOWTER TYPE 9570 phono cartridge transformer
SOWTER TYPE 9570 phono cartridge transformer
Connections seem right. Perhaps try a load resistor on the cartridge side,
but this should not the increase level.
Denon DL-103: Load Impedance 100 ohms minimum (40 ohms when using a transformer)
but this should not the increase level.
Denon DL-103: Load Impedance 100 ohms minimum (40 ohms when using a transformer)
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Yes, that's what I have been referring to. Is it normal that my tester reads zero between the cart connection pin and corresponding RCA pin?
Can you elaborate? I am quite new to this and I'm not understanding the relationship between load impedance and the resistor rating. Thanks.
Are you sure your preamp has a 47k input impedance?
If the preamp were set to 100R or 1k instead of 47k, then the cartridge would see
a far too low impedance, and the transformer secondary would be too heavily loaded.
What preamp do you have?
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I'm using Roy Mottram's PH-16. The impedance for my previous MM was 47K and I adjusted it to 100 which is the default suggested value for MC. So I guess I should adjust the preamp mipedance to 1K before adding a resistor?
That is the problem. The preamp input impedance must be much higher than 100 ohms to use the transformer.
Since the transformer changes the impedance by x100, and the minimum cartridge load is 100R,
you want the preamp input impedance to be 10k or more.
If you change the preamp input back to 47k, then the cartridge will see 470 ohms, which should be fine.
Try this first, with no added cartridge resistor.
To try it with the 100 ohm minimum allowed cartridge load impedance, also add shunt 127 ohm resistors
at the cartridge side. It will likely sound fine without these, though.
Since the transformer changes the impedance by x100, and the minimum cartridge load is 100R,
you want the preamp input impedance to be 10k or more.
If you change the preamp input back to 47k, then the cartridge will see 470 ohms, which should be fine.
Try this first, with no added cartridge resistor.
To try it with the 100 ohm minimum allowed cartridge load impedance, also add shunt 127 ohm resistors
at the cartridge side. It will likely sound fine without these, though.
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That was it! Thank you so much. I clearly need to get my notions of load and impedance down before I continue working on DIY systems...
A step-up transformer transforms voltage up by N, and transforms impedance up by N^2, which is NxN.
So, since my pre has dip switches that allow for different combinations, from 68K to 19.4K. I tried e.g. 27.8K and I did not hear a great difference. Is there an optimum setting aside from what I can hear?
Many reviews seem to recommend 100 ohms, so I'd use the lowest available impedance, 19.4k.
This would load the cartridge with 194 ohms.
This would load the cartridge with 194 ohms.
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Just to add one little note.
You should NEVER measure neither your cartridge or your SUT aqcross the coils with a DMM (ohm setting).
In worst case, specially for the SUT, you could permanently magnetize the core, witch means, the SUT will be more or less ruined and not work as intended 🙂
You should NEVER measure neither your cartridge or your SUT aqcross the coils with a DMM (ohm setting).
In worst case, specially for the SUT, you could permanently magnetize the core, witch means, the SUT will be more or less ruined and not work as intended 🙂
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