studiostevus...Hi !
Nothing fancy on the primary side, just a fuse. I could not see a real practical use for a thermistor here. I've used a thermistor where inrush currents are a problem because of capacitor charging, and it can help protect transformer windings. Not an issue with the transformer or filtering in this circuit though.
Gary
Hi marconi118,
The latest version is the TDA1541A-MK10. It runs either on local shunt regulators powered through passive multi-order balanced filters or from passive multi-order balanced filters with embedded zener diodes.
This module will be part of the SD8-player project (attached pictures).
First picture shows SD8-transport, TDA1541A-MK10 DAC and stepped shunt volume control modules as they will be mounted in the 15mm thick housing. Following pictures show the SD8-transport, TDA1541A-MK10 and stepped shunt volume control modules.
The SD8-transport offers local storage of up to 1 Tera bytes (using 128Gb SDXC cards). Theoretical limit is 8 * 2 = 16 Tera bytes. It has IR-USB interface for optional computer-based browsing, IR remote control and local keyboard. It runs on a single microcontroller. System clock is kept as low as possible (28.288 MHz) in order to minimize ground-bounce. Display is static (no multiplexing).
The TDA1541A-MK10 has 4 on-board discrete shunt regulators, masterclock / clock buffers / clock dividers, DC reference (DC-coupled output), RF JFET current buffers, and the latest soft-sync DEM clock.
The stepped shunt volume control is based on Rhopoint resistors and low power signal relays with gold-plated contacts. It has one AUX input for an external audio source. There are no relay contacts in the series with the signal path. It has 1 on-board shunt regulator.
The latest version is the TDA1541A-MK10. It runs either on local shunt regulators powered through passive multi-order balanced filters or from passive multi-order balanced filters with embedded zener diodes.
This module will be part of the SD8-player project (attached pictures).
First picture shows SD8-transport, TDA1541A-MK10 DAC and stepped shunt volume control modules as they will be mounted in the 15mm thick housing. Following pictures show the SD8-transport, TDA1541A-MK10 and stepped shunt volume control modules.
The SD8-transport offers local storage of up to 1 Tera bytes (using 128Gb SDXC cards). Theoretical limit is 8 * 2 = 16 Tera bytes. It has IR-USB interface for optional computer-based browsing, IR remote control and local keyboard. It runs on a single microcontroller. System clock is kept as low as possible (28.288 MHz) in order to minimize ground-bounce. Display is static (no multiplexing).
The TDA1541A-MK10 has 4 on-board discrete shunt regulators, masterclock / clock buffers / clock dividers, DC reference (DC-coupled output), RF JFET current buffers, and the latest soft-sync DEM clock.
The stepped shunt volume control is based on Rhopoint resistors and low power signal relays with gold-plated contacts. It has one AUX input for an external audio source. There are no relay contacts in the series with the signal path. It has 1 on-board shunt regulator.
Attachments
Your boards look great.
Looks like a lot has changed since your last design, how is the sound developing? Have you given away using the honeycomb mobius loop resistors? Are you still mounting the current divider caps directly to the dac legs under the chip? I've never seen those green G.R. resistors before, might have to look into them, do they perform much better?
Looks like a lot has changed since your last design, how is the sound developing? Have you given away using the honeycomb mobius loop resistors? Are you still mounting the current divider caps directly to the dac legs under the chip? I've never seen those green G.R. resistors before, might have to look into them, do they perform much better?
Dear John,
Nothing amazes me now, coming from you
What is your plan? Focus on the new SDplayer only? Will you be still selling MK8 and MK7 modules for your fans???
I hope modules will be available, the SD player just isn't a practical solution for a lot of us, storage isn't the issue. A TAS asynch USB could be a decent compromise, Jocko/Rankin's Legato proves that. Believe me I know their are a lot of not so great asynch USB implementations but..
Is the format (16 bit data with zero data out to 32 bit) the issue with moving up to USB?
Is the format (16 bit data with zero data out to 32 bit) the issue with moving up to USB?
Hi ryanj,
There are some fundamental improvements in the MK10. This leads to a similar effect as if a blurry faint image is suddenly turned into a sharp realistic image with saturated colors and flood of detail.
The Honeycomb Mobius resistors are fine but it takes a lot of time to manufacture them and that makes them very expensive. These resistors are used in the MK10 (4 pieces), volume control (16 pieces) and Circlotron monoblocks (6 pieces). So I looked for a readily available replacement resistor with similar properties.
Both is possible now, PCB or chip mounting. I used PCB mounting on the MK10 prototype for easy chip comparison.
They are Rhopoint non-inductive wirewound precision resistors (0.01 ... 0.1%).
Here is a quote from following article about resistor noise:
'Wirewound resistors are the best choice for noise, followed by metal film, metal oxide, carbon film, and lastly, carbon composition'
Resistor Types--Does It Matter?
In order to reveal every last detail it helps to lower system noise floor so details won't be burried too deep below the noise floor.
Apart from resistor noise (every resistor produces noise) it's desirable to have a residual noise spectrum that's still pleasing to the ear (non-linear characteristic). To me personally non-inductive wire wound resistors subjectively sound much more natural compared to bulk metal foil that also offer low noise. This is possibly a result of resistor noise spectrum.
There are some fundamental improvements in the MK10. This leads to a similar effect as if a blurry faint image is suddenly turned into a sharp realistic image with saturated colors and flood of detail.
The Honeycomb Mobius resistors are fine but it takes a lot of time to manufacture them and that makes them very expensive. These resistors are used in the MK10 (4 pieces), volume control (16 pieces) and Circlotron monoblocks (6 pieces). So I looked for a readily available replacement resistor with similar properties.
Both is possible now, PCB or chip mounting. I used PCB mounting on the MK10 prototype for easy chip comparison.
They are Rhopoint non-inductive wirewound precision resistors (0.01 ... 0.1%).
Here is a quote from following article about resistor noise:
'Wirewound resistors are the best choice for noise, followed by metal film, metal oxide, carbon film, and lastly, carbon composition'
Resistor Types--Does It Matter?
In order to reveal every last detail it helps to lower system noise floor so details won't be burried too deep below the noise floor.
Apart from resistor noise (every resistor produces noise) it's desirable to have a residual noise spectrum that's still pleasing to the ear (non-linear characteristic). To me personally non-inductive wire wound resistors subjectively sound much more natural compared to bulk metal foil that also offer low noise. This is possibly a result of resistor noise spectrum.
Hi,
Just a note to second the use of Rohpoint resistors in Audio Applications. I have been using them since the mid 90's for critical applications and nothing else really compares.
If I am going to pay a lot of money for a resistor, why not get the best?
Ciao T
(PS, yes I have tried the "usual suspects")
Just a note to second the use of Rohpoint resistors in Audio Applications. I have been using them since the mid 90's for critical applications and nothing else really compares.
If I am going to pay a lot of money for a resistor, why not get the best?
Ciao T
(PS, yes I have tried the "usual suspects")
Hi,
It's worth directly calling Rohpoint.
I usually found they had the values I needed. their MOQ for special values was sensible last time I looked, so I guess a group buy could be set up, if anyone cares...
FIW, I prefer Mills or similar wirewound resistors for power positions, Rohpoint for low power and Allen Bradley or equivalent carbon composition resistors for "stoppers".
Ciao T
It's worth directly calling Rohpoint.
I usually found they had the values I needed. their MOQ for special values was sensible last time I looked, so I guess a group buy could be set up, if anyone cares...
FIW, I prefer Mills or similar wirewound resistors for power positions, Rohpoint for low power and Allen Bradley or equivalent carbon composition resistors for "stoppers".
Ciao T
would that include TX220Z/TX221Z for power positions? we are talking about subjective preference here, so nobody's opinion trumps another, but although their little brothers receive a lot of attention here, i hardly ever see these excellent parts mentioned
so little known here that when the a bunch of Sfoil version were listed in the FS area along with a truckload of TX2352, the power resistors were not even sniffed at, so i got them all for bugger all. the TX2352 were eaten up in no time. I found that rather confusing, this place really is about fashion sometimes
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Hi,
Not those specific ones, but I have used a wide range of Vishay and Caddock power resistors (all sorts)...
I still take high grade, non-magnetic, non-inductive wirewound instead any film or foil resistor.
Ciao T
Not those specific ones, but I have used a wide range of Vishay and Caddock power resistors (all sorts)...
I still take high grade, non-magnetic, non-inductive wirewound instead any film or foil resistor.
Ciao T
I second the use of wirewounds...even in the DAC I/V position. I have discovered they sound more lively (without being harsh) than anything else I've tried, including the TX2575. (no pitch for Mills here!)
interesting, there really isnt another power resistor like them, though i suppose if you dont like their signal resistors that could translate to a degree. would have thought non-inductive, almost completely tempco neutral foil would be the ideal, with little if any difference to non inductive wire. i favor mills also when i dont have $40 each, but i'm yet to try some of the more exotic EU based cottage industry resistors. i dont have this massive aversion to magnetized parts, what about the transducers? surely these will corrupt the sound?
Hello John,
first of all, thanks for all this work (I am a later comer, it seems........) and this wonderful meta thraed.
I have read many of your posts in this thread, and I am more and more intrigued in the new SD8 Player: I believe that passing from 32 gb sdhc to 128*x sdxc is a fantastic improvement; there is a line on what you wrote, that makes me very interested:
You say that the player will offer a IR-USB interface for pc browsing: does it mean we can launch music (an album, and so on) directly from pc? What kind of visual interface can we expect on this new player? That would make the player very flexible...
Also, when would you think the SD8 player will be ready to be sold?
Thank you for all this research.
Tony
first of all, thanks for all this work (I am a later comer, it seems........) and this wonderful meta thraed.
I have read many of your posts in this thread, and I am more and more intrigued in the new SD8 Player: I believe that passing from 32 gb sdhc to 128*x sdxc is a fantastic improvement; there is a line on what you wrote, that makes me very interested:
You say that the player will offer a IR-USB interface for pc browsing: does it mean we can launch music (an album, and so on) directly from pc? What kind of visual interface can we expect on this new player? That would make the player very flexible...
Also, when would you think the SD8 player will be ready to be sold?
Thank you for all this research.
Tony
Hi antonyfirst,
Yes, and the supplied software can be used on Windows, Mac, and Linux.
Graphical user interface, remotely comparable with iTunes and similar programs. More on this later.
We still need one or two months to complete development. If everything goes as planned I could offer offer the first SD8-players in June.
Yes, and the supplied software can be used on Windows, Mac, and Linux.
Graphical user interface, remotely comparable with iTunes and similar programs. More on this later.
We still need one or two months to complete development. If everything goes as planned I could offer offer the first SD8-players in June.
This is a huge step foward, processor running at a range that has been used in CD players for years rather than an intel-ish speed
. Would be interesting to hear how you handle USB ground.Hi regal,
I use RS232 interface on the SD8-transport processor. Next I use a readily available RS232 > USB converter to enable USB communication.
However, RS232 TX and RX signals from the SD8-transport processor run through slotted IR sensors with at least 2mm air gap. This offers -full- galvanic insulation and vanishing low coupling capacitance between SD8 electronics and connected RS232 > USB converter.
SD8-player only requires short commands at low speed (9600 baud) so we don't need complicated high-speed isolators.
I use RS232 interface on the SD8-transport processor. Next I use a readily available RS232 > USB converter to enable USB communication.
However, RS232 TX and RX signals from the SD8-transport processor run through slotted IR sensors with at least 2mm air gap. This offers -full- galvanic insulation and vanishing low coupling capacitance between SD8 electronics and connected RS232 > USB converter.
SD8-player only requires short commands at low speed (9600 baud) so we don't need complicated high-speed isolators.
SD8-Player
Hello John,
I know you are busy with your the SD8-Player but I hope you can answer some questions anyhow:
What are the board dimensions of the SD8-transport, TDA1541A-MK10 and Volume Control.
Can you give some informatons about the mechanical concept of the SD8-Player.
The MK10 board has 4 embedded Shunt regulators. Do reuse the concept/schematic described in post #4175 (cap multiplier / parallel constant current sources on each leg, shunt regulator) or is this concept already out-dated.
For the MK10 you are using a new DAC output stage based on SMD JFETs as current buffer.
Could you please tell what JFET you use or post a schematic?
Hello John,
I know you are busy with your the SD8-Player but I hope you can answer some questions anyhow:
What are the board dimensions of the SD8-transport, TDA1541A-MK10 and Volume Control.
Can you give some informatons about the mechanical concept of the SD8-Player.
The MK10 board has 4 embedded Shunt regulators. Do reuse the concept/schematic described in post #4175 (cap multiplier / parallel constant current sources on each leg, shunt regulator) or is this concept already out-dated.
For the MK10 you are using a new DAC output stage based on SMD JFETs as current buffer.
Could you please tell what JFET you use or post a schematic?