Posted 16th September 2013 at 05:28 PM bydvb projekt Updated 12th January 2017 at 10:18 AM bydvb projekt(Stock status update)
The new Tube-I-zator V3.1
The evolution brings the following changes:
- Anode PSU with Salas SSHV Shunt Reg. onboard
- External B+ Input for usage with other Anode PSU
- Heater PSU with C-R-C filtering
- Heater PSU with Softstart circuit
- Heater PSU Power LED
- Design failures corrected
Thanks to John (-ecdesigns-) for the following suggestions!
- Grid stoppers to prevent unwanted oscillations
- Bias current injection for TDA1541A usage
- Pull-down resistors to keep the coupling cap output at GND-potential
Still on the Module:
- Heater switch for 6N2P or 12AX7 usage
An example for a balanced use (e.g. Bufalo II), you could see HERE.
Posted 9th December 2013 at 08:52 AM byjan.didden Updated 10th December 2013 at 07:02 PM byjan.didden
It’s a recurrent issue: you want to build a preamp, a DAC, a phono stage, anything that needs a nominal supply voltage between 3.3 and 15VDC, positive and/or negative polarity. Sometimes you want several supplies to isolate stages from mutual interference via the power supply. So you want a power supply regulator that approaches an ideal DC voltage source as best as possible within reasonable cost. In your search, you inevitably run into the term ‘superreg’ – so where does the name come from and what is it?
The history of very high performance low-voltage regulators is well documented on Walt Jung’s website (www.waltjung.org – look under Library|Regulators & References). An early design that attracted attention was Mike Sulzer’s, published in 1980 and 1981 in Audio Amateur. I added something to that in 1987, and then I was invited by Walt Jung to work on a further improved version. This was published in a series of four articles in Audio Amateur in 1995 by Walt (part...
Posted 25th September 2015 at 01:56 PM byabraxalito Updated 26th September 2015 at 01:35 AM byabraxalito
Since I figured out the reason for needing all those caps in my earlier DAC designs was all brought on by using passive I/V, I'm now a total convert of active I/V in order to do away with the sheer bulk.
Having tried single transistor I/V and loved it, I found there was still some improvement to be gained by biassing the common-base transistor with additional current sources to reduce its input impedance. Since getting down to the region of 1ohm would require some 25mA of bias which isn't well suited to portable applications I decided to have a go at using feedback to obtain the impedance I'm seeking.
I'm not using an off-the-peg CFB amp because they still turn out to be fairly power supply quality susceptible (subjectively speaking) so here's a design I hope that greatly reduces the supply impedance requirements so that it can be used in a portable player.
The picture shows the second prototype I/V stage, coupled to a 6th order Chebyshev anti-imaging...
Posted 7th January 2010 at 06:10 PM byjan.didden Updated 11th February 2010 at 04:31 AM byJason
There are lots of types of voltage regulators, but in this installment I’ll talk about series regulators.
What’s a regulator? It’s all in the name: it REGULATES the voltage to the circuit to be powered to keep it constant and as free of noise and ripple as practical. The ‘regulation’ means that there is some circuitry that compares a reference voltage, like from a zener diode, to the regulated output voltage, and then uses the difference between the two to adjust another element to null that difference. The ‘compare-and-correct’ is crucial for a regulator, and is done by negative feedback….
Look at Fig 1: is there a regulator in there? No, they are all circuits that try to give a constant, ripple free voltage, but if you start to draw varying currents from them, the output will vary with that current and there is no mechanism that somehow tries to null out that variation. Fig 1c is better than 1b, because Q1 buffers the voltage from the zener reference, so...
Posted 29th March 2010 at 01:33 AM byquanghao Updated 29th March 2010 at 02:16 AM byquanghao
INTRODUCTION
After the good result obtain with the DAC End I have design with Nguyen Quang Hao a set of boards to create a cheaper project with a sonic performances very near.
The No Oversampling DAC give a more natural sound but if you ear the TDA1541 and TDA1543 seem to lose details.
The AD1865N-K with passive I/V give a perfect combination, natural sound and all the details.
The AD1865N-K give the better performances with a 200ohm MK132 Caddock as passive I/V.
In this configuration the output signal is too low to drive any amplifier so I have design for the AD1865N-K the better output stage.
This DAC use a single ended vacuum tube amplifier without the expensive output transformers used in my original DAC End.
The DAC board follows the original design but has been inserted a jump to switch the phase of output signal.
In any vacuum tube stage the signal on the anode is in out phase...
Posted 20th August 2011 at 08:32 AM bydvb projekt Updated 30th November 2016 at 10:25 AM bydvb projekt
The Red Baron
aka TDA1541A DAC V3.0
The evolution brings the following changes
- Direct shunt voltage inputs with shortest onboard traces
- I2S In-/Outputs with shortest onboard traces
- Upgrades DEM Synchronizer
- Onboard Grounded-Gate MOSFET Current Buffer I/V Stage
(-ecdesigns- MK7 version)
- Compacter design
Still on the module
- Separate GND-Trace for DEM-Synchroinizer
- Master/Slave connectors for parallel DAC module usage
and external I/V Buffer stages e.g.
Tube-I-zator & DDNF Stage
- Groundplane
- no SMD Design
The PCB has the following data:
Material: FR4 - 2mm
Layers: 2
Board size: 125x73 mm
Posted 12th May 2013 at 07:51 PM byalexcp (My DIY projects)
This is a project developed by Douglas Self and published in the Elektor in October and November 2010.
The idea is rather unusual: "An interesting power amplifier can be made by connecting enough 5532s in parallel, how about 32 for a start? This may sound like a radical course of action, but it actually works very well, making it possible to build a very simple amplifier that retains not only the excellent linearity but also the power-supply rejection and the inbuilt overload protection of the 5532, which reduces the external circuitry required to a minimum."
Elektor used to sell PCBs for this project, which I used. I modified the circuit slightly to incorporate an active volume control along the lines of Douglas Self's preamplifiers.
Posted 30th December 2013 at 04:35 AM bywlowes Updated 22nd September 2014 at 01:10 AM bywlowes(add pic)
Two months ago I had great ambitions to complete a long in the planning short on execution music server by xmas. Seems I am too busy and just having too much fun listening to my system to make progress on big projects.
However, in a very low key way my system has made some stunning gains over the 2013 holiday.
My happy 6 year journey with a Lightspeed linestage finally ran afoul when an LDR packed it in. I retooled with some on hand bits while waiting for new LDRs to arrive. A snaffu with my order delayed that whole process. Meanwhile, my wonderful wife asked me what I wanted for xmas. I had been reading Arthur Salvatore's site and became interested in using an autoformer from Dave Slagle for my linestage. If your read the reviews and the technical specs, its intriguing. My system is perfect for passive. I only listen to a music server with triode ouput stage, short interconnects to OTL amps and overall have lots of gain.
Posted 7th March 2015 at 08:43 AM byabraxalito Updated 6th May 2017 at 12:58 PM byabraxalito
The Schitt Yggy DAC has already created something of a stir over on Head-Fi amongst those who've heard pre-production prototypes. Its of interest not just because of the pre-launch buzz but also because the designer (Mike Moffat) is one of the long-time seasoned guys in the field. He says this is the best practical DAC he knows how to build. And its priced ISTM very reasonably given the amount of tech it embodies ($2300) - the DAC chips come from ADI and are $64 a piece on the manu's website. He's using 4 of them but says he had to address the glitching of the DAC without using a sample-hold which sounds like ***.
The chip is the AD5791BRUZ which ADI designed for industrial/scientific/medical applications rather than for audio. Datasheet attached.
Having looked over the DS what strikes me as interesting is that this is a 20bit DAC (1ppm) yet the 1kHz THD performance (p4) isn't anything to write home about (-97dB) and that figure is given at a very low sample rate...