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I finally finished my Sowter 9335 based volume control.
Most impressive. Most impressive!!!!
HiIt looks great. Is there any wiring schematics for our reference.
thanksbest regards,
ben
Actually, wiring is very simple. Transformer has two primary wires and 26 + 1 secondary wires. Connect all inputs to selector switch, two wires from selector go to transformer primary and all the 26 outputs should be connected to appropriate switch (search the archives for available options).I made wiring little bit more complicated by having pair of additional balancing transformers, ground lift switches and separate effects loop available. You can ignore that completely.
NT
Looks great!Much more complicated than mine - S&B TX's - one input, one output!
Thanks!I used smaller transformers (3575) to balance the signal coming from RCA input.
I used smaller transformers (3575) to balance the signal coming from RCA input.What's the point of balancing the signal after it's already entered the chassis? All that will do is help with common-mode noise induced into the line between the output of the transformers on the input and the input of the TVC. And that line is only there in the first place because of the transformers on the input.
The input of the TVC is already inherently balanced and should give you excellent common-mode rejection even if you're feeding it from an unbalanced source. If you want to balance the signal for a little more rejection, you'd want to balance it at the source component's output. It's the common-mode noise induced into the line between the source component and the TVC that you want to reject.
In any case, great work on the construction! I don't think I could ever muster enough patience for something like that. I'm envious. :)
se
Steve,What's the point of balancing the signal after it's already entered the chassis? .. Simple man, it gives you choice, if half your inputs are balanced, and the other unbalanced, then you route one set through a transformer to drive the either balanced or unbalanced TVC..
Just my 2 cents
Owen
What's the point of balancing the signal after it's already entered the chassis? .. Simple man, it gives you choice, if half your inputs are balanced, and the other unbalanced, then you route one set through a transformer to drive the either balanced or unbalanced TVC..Except that the TVC's input is inherently balanced (floating) and can be driven directly from either a balanced or unbalanced source. In other words, there's no separate configuration of the TVC for balanced or unbalanced sources.
I paid a visit to Sowter's web site and Brian has updated the application schematics for the TVC which includes a configuration using an added input transformer. The purpose of the added transformer isn't to balance the signal after it's entered the chassis, but rather for improved common-mode noise rejection at the primary input.
The Sowter TVC has rather poor common-mode noise rejection, only 50dB at 50Hz. Using a dedicated input transformer in front of it such as Sowter's 3575 would provide better input common-mode noise rejection than could be achieved with the TVC alone.
Sowter doesn't give any common-mode rejection specs for their 3575, but a good input transformer should be able to offer upwards of 100dB or more of common-mode noise rejection.
se
Having great disproportion between knowledge and desire to make this good, I had to rely on what I was told. Official reply from Sowter was that both the transformer input and output should be either balanced or unbalanced, so having balanced output my only option was to balance the input coming from RCA.Later they relaxed their requirements, as it could be observed on their web site. I have to emphasize that I was not under impression that they are trying to sell me extra hardware.
Anyway, it sounds very good.
Thanks for your kind observations.
Very nice, indeed!
A question: What other components did you use?
"Come, or you shall be late""Late?"
"What is your name Earthling?"
"Dent, Arthur Dent"
"Late, as in the Late Dent Arthur Dent. It's a kind of threat you see. never was terribly good at them"
Smoke me a kipper...I'll be Back for Breakfast.Cheers
welly
Hammond metal box
Shallco D switch, 2 decks, 1 pole, 26 positions, shorting
Shallco J selector switch, 2 decks, 3 poles, 4 positions, non-shorting
Neutrik XLR, Canare RCA
Thanks!
happy listening!
slarti
nt
Very nice work, well laid out. The rotary switche for the volume switching is also very nice.What are the 4 toggle switches on the back for?
How does it sound?
Rookster
Little toggle switches are used for lifting ground on inputs and outputs (it appears it is not needed).It sounds better than any other preamp I have heard (you can sense some bias here :) Seriously, I can hear details I never noticed before and dynamics is excellent, even at very low levels. Every instrument now has its own space and stereo picture is very deep.
Search around asylum for more impressions. I think the transformers are the way to go.
It sounds better than any other preamp I have heard (you can sense some bias here :) Seriously, I can hear details I never noticed before and dynamics is excellent, even at very low levels. Every instrument now has its own space and stereo picture is very deep.Yeah, I think much of that is due to eliminating residual noise caused by interchassis currents. The TVC (or any transformer for that matter) eliminates those currents due to its galvanic isolation.
Search around asylum for more impressions. I think the transformers are the way to go.
I haven't tried any of the TVCs yet but I'm looking forward to it. I've been using input transformers for years and incorporating signal attenuation into the transformer has a definite appeal.
se
I've enjoyed the clean, dynamic sound of the TX, but I have a question I hope you don't mind answering:I inserted a voltage divider, essentially two resistors between my ART DI/O DAC and the TX's to reduce the DI/O's 7 volts and get my volume down to more acceptable levels. I believe the resistors involved are around 1.5 and 3.4 kohm...
The issue is that while the divider achieved an appropriate reduction in volume, I also got a whole lot of buzz/static. Grounding components together (DAC, AMP) made the buz disappear.
Am I committing an audio-engineering crime by inserting a voltage divider on a tranny?
I've enjoyed the clean, dynamic sound of the TX, but I have a question I hope you don't mind answering:I inserted a voltage divider, essentially two resistors between my ART DI/O DAC and the TX's to reduce the DI/O's 7 volts and get my volume down to more acceptable levels. I believe the resistors involved are around 1.5 and 3.4 kohm...
The issue is that while the divider achieved an appropriate reduction in volume, I also got a whole lot of buzz/static. Grounding components together (DAC, AMP) made the buz disappear.
I'm not sure what caused that. I think perhaps that the shunt resistor of your attenuator produced some sort of level shift in the primary. Normally the primary floats and the secondary just follows the primary, but with that shunt resistor from your attenuator would lock in the primary and you might end up passing along any differences in ground potententials between chassis.
I'd really need to give it more thought though to be sure.
What I can't understand is why on earth ART chose a +20dBu full scale output for their DIO.
se
Well I gave it some more thought and ultimately couldn't see how your attenuator circuit would have caused such a problem. I also talked to Dale over at Jensen and he concurred. Unless there is something wrong with the transformer or something wasn't wired up right, you shouldn't have any hum/buzz problems.So I'm stumped.
se
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