Hi,
so I start this thread now without having much to tell.
Some links which may be helpful first:
S&B TX-102 official page
Hifi NEws (UK) Review
Hifi World (UK) review
audiotweaks bent kit review
audioasylum t.Loesch review
Bent audio ... some schematics etc.
Cheers
Christian.
so I start this thread now without having much to tell.
Some links which may be helpful first:
S&B TX-102 official page
Hifi NEws (UK) Review
Hifi World (UK) review
audiotweaks bent kit review
audioasylum t.Loesch review
Bent audio ... some schematics etc.
Cheers
Christian.
Bent audio NOH preamp Assembly Photos
Bent audio download page .... schematics
Bent audio: TX-102 primary wiring schematic .... about +0dB and +6dB
bent audio: complete schematic with RCA and XLR inputs and outputs ... everything else
Cheers
Christian.
Bent audio download page .... schematics
Bent audio: TX-102 primary wiring schematic .... about +0dB and +6dB
bent audio: complete schematic with RCA and XLR inputs and outputs ... everything else
Cheers
Christian.
Thanks for the info. I am still interested in a remote control for volume. Perhaps one using FET switches for each step.
Hi,
easiest in my opinion is to use a rotary switch and a standard remote control kit in combination with a small DC motor and belt instead of motorized pot. A solution using relays is too big I guess.
Cheers
Christian.
easiest in my opinion is to use a rotary switch and a standard remote control kit in combination with a small DC motor and belt instead of motorized pot. A solution using relays is too big I guess.
Cheers
Christian.
Great to see a build thread up for the TX102's, thanks krishu.
I got mine yesteday but I wont be able to start to build anything until later in January. At the moment I am not sure how I will approach my Pre Amp. I am looking forward to seeing other builders ideas.
I would also love a remote control solution but I dont want to do anything to compromise the sound quality.
Is there such a thing as a motorised multi position switch that we could use, I like the idea of a switch driven by a belt as it should be possible to keep the control system almost completly removed from the passive volume control. However I dont like the idea of making such a thing!! unless someone else could work out how to do it ;-)
PS I notice my transformers have different coloured wires, one has mostly black the other mostly white, is that significant?
I got mine yesteday but I wont be able to start to build anything until later in January. At the moment I am not sure how I will approach my Pre Amp. I am looking forward to seeing other builders ideas.
I would also love a remote control solution but I dont want to do anything to compromise the sound quality.
Is there such a thing as a motorised multi position switch that we could use, I like the idea of a switch driven by a belt as it should be possible to keep the control system almost completly removed from the passive volume control. However I dont like the idea of making such a thing!! unless someone else could work out how to do it ;-)
PS I notice my transformers have different coloured wires, one has mostly black the other mostly white, is that significant?
Konnichiwa,
That is intentional. One transformer is for L the other for R. Using different colours makes the wire spagetti a little better to work through.
Sayonara
wytco0 said:
That is intentional. One transformer is for L the other for R. Using different colours makes the wire spagetti a little better to work through.
Sayonara
What's too big for you? I got everything to fit on a single euroboard (16*10cm) using standard sized relays, or you could use squadras layout using four 8*5cm boards.krishu said:
You can see the layout of my board here: http://electronics.dantimax.dk/Kits/11021716092.html
The price could get lower with a groupbuy...
Best regards,
Mikkel C. Simonsen
Have you found sourcing for the motor & remote? It seems that there's also a matter of torque involved...
Otherwise, the "mechanical remote" seems indeed to be a simpler solution.
Hi,
you can use almost any DC motor when you don't use 1:1 pulleys.
Remote control kits are available from different sources, one to mention is Alps. This is far less than USD100 including remote control.
There is one question Kuei Yang Wang may answer:
On the S&B website they tell about "a series RC Circuit (snubber)" ... can you please suggest values for both R and C? Thanks!
Cheers
Christian.
you can use almost any DC motor when you don't use 1:1 pulleys.
Remote control kits are available from different sources, one to mention is Alps. This is far less than USD100 including remote control.
There is one question Kuei Yang Wang may answer:
On the S&B website they tell about "a series RC Circuit (snubber)" ... can you please suggest values for both R and C? Thanks!
Cheers
Christian.
Konnichiwa,
This is a carryover from the MK I TX-102, it should not be needed for the current one, if you where to need it (due to system interactions) you need to measure the response and then design in the snubber for the actual system, no "one size fits all" value set can be given.
Sayonara
krishu said:
This is a carryover from the MK I TX-102, it should not be needed for the current one, if you where to need it (due to system interactions) you need to measure the response and then design in the snubber for the actual system, no "one size fits all" value set can be given.
Sayonara
Kuei Yang Wang said:
Hi,
thanks,
so lets hope we don't need it. If however we need it, how do I know this? Does it have to be measured or will I hear it?
Thanks
Christian.
Konnichiwa,
It has to be measured, as does the correction, you would need to be able to measure pretty accuratly up to several 100KHz at least.
Sayonara
krishu said:
It has to be measured, as does the correction, you would need to be able to measure pretty accuratly up to several 100KHz at least.
Sayonara
Kuei Yang Wang said:
Hi,
OK, so I better ask my R&D friend(s) ... 😉
unfortunately I am away for some days during Weihachten so I can't solder
Cheers
Christian.
checking the wiring diagram for the TX102's, it all seems fairly straight forward, but I have a red wire which is unmarked, which I assume is the screen to ground wire. Can anyone confirm this?
I intend to wire the earths such that the earth to the case and the transformer screen are wired to the protective earth connection and to wire the signal -ve's through the interconnects to the star point on the power amp power supply. Is this OK?
Finally, if I keep the source to TVC interconnect short, <0.5M, what distance should I be able to have the TVC to power amp interconnects, is 1.5M to 2M OK? I'm using a CDP and a phono stage.
Kev
I intend to wire the earths such that the earth to the case and the transformer screen are wired to the protective earth connection and to wire the signal -ve's through the interconnects to the star point on the power amp power supply. Is this OK?
Finally, if I keep the source to TVC interconnect short, <0.5M, what distance should I be able to have the TVC to power amp interconnects, is 1.5M to 2M OK? I'm using a CDP and a phono stage.
Kev
Konnichiwa,
Yes, that is how JB usually does it. Unmaked = Screen/core, marked +/++/-/-- = input, marked with numbers = Output Taps
There are many ways to do things. I recommend to connect the passive preamp chassis and thescreens together. Input grounds (RCA Ring or XLR pin 1) are connected also here, usually I recommend leaving a bit resistance (100R...1K) there, rather than "hard" ground.
If you have the space you can add a 3-Way toggle switch to each input, allowing "soft" ground (via resistor), hard ground (direct to chassis ground) and floating.
It is also worth RF terminating the screens (eg ring on RCA, Pin 1 on XLR) to the chassis via a 51R/10nF (low inductance) series circuit.
Finally, the output should also have grounding options of floating or RCA Ring/Pin 1 XLR grounded.
Under ideal conditions you can ground the output and have all inputs floating, but in case of some gear this induces hum, that is how I ended up soft grounding the input grounds to the chassis and instead floating the output.
Neither input nor output cables need to be particulary short (unlike other passive pre's). Of course, say 10m of 1nF/1m Goertz cable is still out, but pretty much any sensible capacitance cable (<= 100pF/m) can be tolerated in quite a bit of length both before and after the TX102.
Best way of viewing the worst case of the unity gain (no stepup) connection in maximum volume position is to think of the transformer as a 600 ohm Resistor. This you insert in series with your source's output impedance.
If you want to use the stepup mode be a little more cautious with the load capacitance.
Sayonara
KevinTams said:
Yes, that is how JB usually does it. Unmaked = Screen/core, marked +/++/-/-- = input, marked with numbers = Output Taps
KevinTams said:
There are many ways to do things. I recommend to connect the passive preamp chassis and thescreens together. Input grounds (RCA Ring or XLR pin 1) are connected also here, usually I recommend leaving a bit resistance (100R...1K) there, rather than "hard" ground.
If you have the space you can add a 3-Way toggle switch to each input, allowing "soft" ground (via resistor), hard ground (direct to chassis ground) and floating.
It is also worth RF terminating the screens (eg ring on RCA, Pin 1 on XLR) to the chassis via a 51R/10nF (low inductance) series circuit.
Finally, the output should also have grounding options of floating or RCA Ring/Pin 1 XLR grounded.
Under ideal conditions you can ground the output and have all inputs floating, but in case of some gear this induces hum, that is how I ended up soft grounding the input grounds to the chassis and instead floating the output.
KevinTams said:
Neither input nor output cables need to be particulary short (unlike other passive pre's). Of course, say 10m of 1nF/1m Goertz cable is still out, but pretty much any sensible capacitance cable (<= 100pF/m) can be tolerated in quite a bit of length both before and after the TX102.
Best way of viewing the worst case of the unity gain (no stepup) connection in maximum volume position is to think of the transformer as a 600 ohm Resistor. This you insert in series with your source's output impedance.
If you want to use the stepup mode be a little more cautious with the load capacitance.
Sayonara
this weekend, can't wait 