It took a while...
..but at the end I completed my DCB1. Here are some pictures. I am using the same switch to power the buffer and to select input. pos1 is off, 2-5 input select. I have a primitive power supply for the relay that switch on the system.
If I remember well, I have a 3ohm resistor to set the current. (But I could be very wrong here)
I left a lot of space in the chassis, as this is only the first iteration. I have some options that I will consider (and some related questions):
1) Buffer before and after the pot. Question: in this case, can I use a single power supply ?
2) Balanced. Here I guess that the matching and the bias handling can become a mess.
3) Remote control for volume and input.
Thanks,
Davide
..but at the end I completed my DCB1. Here are some pictures. I am using the same switch to power the buffer and to select input. pos1 is off, 2-5 input select. I have a primitive power supply for the relay that switch on the system.
If I remember well, I have a 3ohm resistor to set the current. (But I could be very wrong here)
I left a lot of space in the chassis, as this is only the first iteration. I have some options that I will consider (and some related questions):
1) Buffer before and after the pot. Question: in this case, can I use a single power supply ?
2) Balanced. Here I guess that the matching and the bias handling can become a mess.
3) Remote control for volume and input.
Thanks,
Davide
Attachments
This is a Mezmerize multi relay input version board. Has the pot PCB routed before the buffer as it should. Single shunt supplies per channels are inherent too. You probably got 33R, not 3R. Check this out, it defines dissipation. Would not use more than 200mA with your sinking arrangement. I=~2V/settingR. Looks good.
I was thinking now, my system has nine salas regulators:
I made two DACs, an AD1865 (3 lv + 1hv) and a dual mono Buffalo II (3 lv) and finally the B1 (2 lv)
The aim was to compare the two DACs that have nothing in common. I have an idea to try a balanced AD1865 with two chips. One day i feel insane i will do.
Speakers are Sonus Faber Grand Piano and the sub a SF Gravis B1.
I am playing now the Buffalo with F5 and B1 and it sound fabulous. I noticed that with the Buffer the bal-se converter of the legato behaves much better.
BR,
Davide
I made two DACs, an AD1865 (3 lv + 1hv) and a dual mono Buffalo II (3 lv) and finally the B1 (2 lv)
The aim was to compare the two DACs that have nothing in common. I have an idea to try a balanced AD1865 with two chips. One day i feel insane i will do.
Speakers are Sonus Faber Grand Piano and the sub a SF Gravis B1.
I am playing now the Buffalo with F5 and B1 and it sound fabulous. I noticed that with the Buffer the bal-se converter of the legato behaves much better.
BR,
Davide
That's some regulated guy I would say! 
Greetings,
I've finally been able to complete my build - did it in 3 separate sections (Rectifier+Smoothing, Shunt Regulator, and Buffer) over the last 3 months. Much easier for me to understand and troubleshoot should a section not work as intended.
Here are my measurements using a 12-0-12 2A EI transformer (will be replacing it sometime as it gets warm to the touch after 2 hours):
Positive Rail:
Vin = 15.75V (input to Reg)
Vout = 10.59V (reg output)
V @20R 2W = 2.79V (slightly hot-rodded)
Negative Rail:
Vin = -15.75V (input to Reg)
Vout = -10.66V (reg output)
V @20R 2W = 2.37V (slightly hot-rodded)
Buffer Section:
2.3mV and 1.7mV
Sounds marvelous compared to before (as I had built the buffer section first, I was running it with a +-12v switch mode PSU). Much smoother and quieter (switch mode PSU gave a slight audible buzz).
Some observations for the group:
1) The measurements look normal to me (aside from the -ve rail reading higher than the +ve one).
2) Both CCS FET (the one's AWAY from the filter caps) run warm-hot i.e. with a simple heatsink they can be held continuously without burning your fingers.
3) The 20R 2W resistors get hot i.e. they can be held but feel hot to the touch.
My question - As I am buying a new transformer, should I just get another 12-0-12V higher VA rating or go for a 15-0-15V (or 18-0-18V which seems more common where I shop).
Thank you in advance for all your responses.
I've finally been able to complete my build - did it in 3 separate sections (Rectifier+Smoothing, Shunt Regulator, and Buffer) over the last 3 months. Much easier for me to understand and troubleshoot should a section not work as intended.
Here are my measurements using a 12-0-12 2A EI transformer (will be replacing it sometime as it gets warm to the touch after 2 hours):
Positive Rail:
Vin = 15.75V (input to Reg)
Vout = 10.59V (reg output)
V @20R 2W = 2.79V (slightly hot-rodded)
Negative Rail:
Vin = -15.75V (input to Reg)
Vout = -10.66V (reg output)
V @20R 2W = 2.37V (slightly hot-rodded)
Buffer Section:
2.3mV and 1.7mV
Sounds marvelous compared to before (as I had built the buffer section first, I was running it with a +-12v switch mode PSU). Much smoother and quieter (switch mode PSU gave a slight audible buzz).
Some observations for the group:
1) The measurements look normal to me (aside from the -ve rail reading higher than the +ve one).
2) Both CCS FET (the one's AWAY from the filter caps) run warm-hot i.e. with a simple heatsink they can be held continuously without burning your fingers.
3) The 20R 2W resistors get hot i.e. they can be held but feel hot to the touch.
My question - As I am buying a new transformer, should I just get another 12-0-12V higher VA rating or go for a 15-0-15V (or 18-0-18V which seems more common where I shop).
Thank you in advance for all your responses.
After some upgrades here's what I found out.
I have changed the signal wiring to 0.6mm PTFE silver plated single core copper. The change from 1mm sing core Cu (taken from my genuine CT100 coaxial) was quite noticable. Mostly in the middle region. It sounded so good, I was considering already divorcing my upgrade bug.
But together with my wires came all 8 Takman resistors. I changed only 4 220R, as per Tea-Bag advice. The sound improved again! Maybe the mids lost a milligram of edgyness, straight forwardness, "in-your-faceness" but I get it as a good thing. Most importantly, it improved the upper region so much, that I never thought my Spendors
were capable producing of.
Today I've received 4 TX2575 resistors... I feel hesitant about another upgrade as I like the present sound. Except one thing. My amp started huming. I suspect the ground loop.
I have changed the signal wiring to 0.6mm PTFE silver plated single core copper. The change from 1mm sing core Cu (taken from my genuine CT100 coaxial) was quite noticable. Mostly in the middle region. It sounded so good, I was considering already divorcing my upgrade bug.
But together with my wires came all 8 Takman resistors. I changed only 4 220R, as per Tea-Bag advice. The sound improved again! Maybe the mids lost a milligram of edgyness, straight forwardness, "in-your-faceness" but I get it as a good thing. Most importantly, it improved the upper region so much, that I never thought my Spendors
were capable producing of.
Today I've received 4 TX2575 resistors... I feel hesitant about another upgrade as I like the present sound. Except one thing. My amp started huming. I suspect the ground loop.
Are the takman warmer than the resistors they replaced?From what i read they should be warm but detailed
Hi,
Before replacing them, I've read same statements saying they sounded warmer or that they made some regions sound recessed.
In my experience, I've only got more details especially in the upper region and any other regions just right in their place. It might depend on the rest of the system, though.
That is my first impression. Prehaps, I should wait for them to break in.
I'm also very interested in sound if I had all the 8 critical resistors changed to takman carbons.
Before replacing them, I've read same statements saying they sounded warmer or that they made some regions sound recessed.
In my experience, I've only got more details especially in the upper region and any other regions just right in their place. It might depend on the rest of the system, though.
That is my first impression. Prehaps, I should wait for them to break in.
I'm also very interested in sound if I had all the 8 critical resistors changed to takman carbons.
Best are Z foils if someone can afford, along with a switching or light volume pot. Those are the most neutral and high res choices. All other stuff can be synergistic in system's concept approach. In general this circuit is high resolution buffering anyway from generic to lavish build cost. That is why everything is audible. People tend to keep, I don't see enough swapped around from the hundreds built.
Of course, I have a little itch to place these Z foils I have by hand right away. But I want to let carbons brake in too. Just to hear the change, if there's going to be any.
At this moment, already, the overall impression is "listen and weep"... or do whatever music makes you to. My system didn't give this feeling, before I diyed this buffer.
What could have I asked more for the first build!
Maybe that without the hum. Let's hope I'm going to cure it tonight.
I have a DACT style stepped pot to test too. Will report.
At this moment, already, the overall impression is "listen and weep"... or do whatever music makes you to. My system didn't give this feeling, before I diyed this buffer.
What could have I asked more for the first build!
Maybe that without the hum. Let's hope I'm going to cure it tonight.
I have a DACT style stepped pot to test too. Will report.
Siberia -
Did you put a CL60 between central ground and Earth ground on DCB1?
This can help. Sometimes not.
I think your take on the takman's is right on. They have a high resolution sound with a little touch of mellowness in the mids, and a top end that may sparkle too much for some taste.
I would wait a month before putting in the zfoils. At least 10 or so good listening sessions.
Ive listened to plenty of resistors in my rig - The Zfoils are hard to fault, but they won't balance out anything in a system if it's too bright or dark.
Did you put a CL60 between central ground and Earth ground on DCB1?
This can help. Sometimes not.
I think your take on the takman's is right on. They have a high resolution sound with a little touch of mellowness in the mids, and a top end that may sparkle too much for some taste.
I would wait a month before putting in the zfoils. At least 10 or so good listening sessions.
Ive listened to plenty of resistors in my rig - The Zfoils are hard to fault, but they won't balance out anything in a system if it's too bright or dark.