Added the set of decoupling SMD low ESR capacitors for each board
Category: Source
Starlight Discrete DAC: more progress
I used a aluminium bar structure to hold both LL7903 transformers and the Russian PIO output capacitors. The LL7903 will be wired in 4:1 and the capacitor will prevent the DC current from the DAC to shunt to ground. Also used some silicon rubber to protect the mu-metal can of the LL7903:
Here are the DAC boards mounted on a PTFE board with a set of copper strips that will be used to solder 10 x 100μF SMD low ESR capacitors to improve decoupling of DC rails:
I think all fits in the box I’m planning to use 🙂
Starlight discrete DAC boards finished
After testing the accuracy of the R and 2R network, thanks to Jon managed to complete my discrete DAC boards for the Starlight CD player. Not very keen to solder SMD ICs but couldn’t get away from the tedious task of soldering 10 ICs:
Now need to continue with the DAC (or the transport). Lots of work to do still…
Starlight Discrete DAC
Resistor ladder soldered. Now it’s time
For the Logic ICs….
IRIAA test box
Testing RIAA stages is a real challenge. However, with current testing gear becoming affordable to us thanks to the development of PCs and sound card interfaces, now you can test your RIAA stage without further excuses. There are software-based solutions to implement IRIAA transfer curve for looking at a flat frequency response of our RIAA stage, but they are not free or easy to implement unless you are skilled on data manipulation on your PC. You can also build your own analogue IRIAA stage. In fact, Morgan Jones suggests a great way of implementing this in his great “Building Valve Amplifiers” (Second Edition) which was recently released. I recommend the book highly, albeit I will not fall in the trap again of buying the e-book version. I was highly disappointed with the e-book release of 4th edition of “Valve Amplifiers”. I guess I will just use my Kindle for reading plain books instead.
The circuit proposed by Morgan Jones is inspired on Hagerman’s paper (thanks Gary B for providing the link) which includes an IRIAA stage for same purposes:
Morgan Jones changed Hagerman’s design component values to fit to the 3.18uS Neuman pole instead of 3.5uS and combined 1% and 0.1% resistor tolerances to improve the accuracy of the IRIAA response. You can get the essence of the circuit from the above diagram.
I modified the circuit proposed by Morgan Jones slightly to fit my requirements and in particular I added the additional resistors to simulate DL103’s output resistance of 40Ω.
I had a nice strong mints sweet metal box from Marks & Spencer and used it ast the housing for the IRIAA stage. A BNC adapter also was added to the input to ensure I could hang the IRIAA box from either the waveform generator or the SC interface:
Inside the IRIAA box
MC and MM outputs
IRIAA box
Input connector
Inside box 2
Inside box 3
Building this box takes just a couple of hours and you will be amazed with the results you can achieve. I wish I could post the diagram but I don’t have Morgan Jones’ permission so I hope this post encourages you to buy the book if you weren’t still convinced to do so.
This IRIAA stage has two outputs. One for MC and the other one for MM. You can see the ideal frequency response below:
Starlight: User Interface
Starlight CD player project started earlier than planned. Today I finished the User Interface PCB with PIC controller and LCD module. Tested and all working fine so far
DL103 cartridge review
This may not be any news to most of you, but after a long time I managed to get the upgrade needed on my turntable: the cartridge. The Denon DL103 was a perfect decision to step up into the MC territory at an affordable cost. Many will say out there that there are better cartridges, but that is not the point of my review.
I tried some MM ones and until now couldn’t get the Lenco + Audiomods arm to sound as good as it sounds now. The DL103 is challenging due to its low compliance and output levels.
Although I have a step-up transformer, I’m saving it for my valve phono stage project which I hopefully will get my hands on next year. Currently still have a solid stage RIAA stage made by Project which sounds really good in my opinion. Shortly will complete my JFET shunt cascode RIAA stage and listen to the difference.
Jeff from Audiomods sent me the copper shim for the headshell but my cartridge screws aren’t long enough to fit both. I was worried on the performance by not adding sufficent mass to the arm, but after testing it, I was surprised to see that it was not the case.
The sound performance is really good. No loss in bass or treble, with a flat response, the dynamics are brilliant. Noise level is very low. Tight drums and clearer sound. I like the detail and even playing loud sections it is great. I will continue to listen to this until I can find anything to dislike from it, so far it’s superb.
A collection of latest images
After upgrading my 26 preamp, turntable and adjusted the system to a great sounding state. Looking forward to play many records now…
HT power supplies
Latest System
26 preamp and 4-65a SE Amplifier
DHT filament supplies (and many of them)
26 and bigger brother 46
Reddish 4-65a
26 preamp Gen3
Lenco turntable
Setting up to play in the evening
Lenco arm board
This is a great new arm board made by Carl to fit my Lenco plinth. I’m planning to add a second plater so needed to raise the tonearm and therefore a new board was required. Carl can make this arm board to fit any requirements. Just get in touch with Carl if you need a special arm board for your plinth.
Lenco turntable (Part II)
Great thing about bank holiday weekends is that you have more time to work on your projects! At least I had this time round.
After doing the initial calibration to the Lenco idler mechanism, I got the turntable finally assembled on the new plinth. It runs very quiet and smoothly despite having not dampened the idler wheeler as recommended in the Lenco Heaven forum. I need to look into it but so far the turntable runs really quiet.
The arm board is a bit lower than it needs to probably. I can adjust the VTA with the micrometer but I should look at raising it to allow the arm to be rotated to the right for best placement. The micrometer is preventing this to happen. Will refine later.
GL75 now on its final place
Audiomods tonearm
First test
Clearaudio virtuoso cartridge
Ok, impressions so far after all this work then. I did many upgrades this time to my system so it is hard to quantify which part contributed the most to the sound improvement. Overall tone and clarity has improved. I suppose that the heavy plinth makes a big difference to the bass clarity. The overall tone improvement and detail is quite likely to be the Audiomods tone arm as well as using the Clearaudio Virtuoso Wood MM cartridge that Tony kindly give me to try.