Salas hotrodded blue DCB1 build

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LucasAdamson

LucasAdamson

Member
Joined 2009
OK - My DCB1 shunt is up and running with a 12-0-12 power supply that is more like 12.5-0-12.5 on the UK national grid.

Anyway, my rails are 9.1v DC and 9.06v DC, not the desired 10v, because my leds were merely max 1.8Vf, and actually read more like 1.7Vf on my meter. What's more, they are not quite as constant as the northern star. When measuring, they took some time to stabilise, and even then I am not convinced that they did stabilise fully - they measured slightly differently the next day. Normal? I don't know. They're Panasonic, but it seems they make some slightly crap stuff too.

Is 9.1v DC OK for a hotrodded DCB1? Should I get a 15v DC R-core transformer? Should I get new leds? What?

By the way, my matched fets are 6.85mA Idss, if it has any bearing on the matter.

Many thanks
Lucas
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
LucasAdamson said:
OK - My DCB1 shunt is up and running with a 12-0-12 power supply that is more like 12.5-0-12.5 on the UK national grid.

Anyway, my rails are 9.1v DC and 9.06v DC, not the desired 10v, because my leds were merely max 1.8Vf, and actually read more like 1.7Vf on my meter. What's more, they are not quite as constant as the northern star. When measuring, they took some time to stabilise, and even then I am not convinced that they did stabilise fully - they measured slightly differently the next day. Normal? I don't know. They're Panasonic, but it seems they make some slightly crap stuff too.

Is 9.1v DC OK for a hotrodded DCB1? Should I get a 15v DC R-core transformer? Should I get new leds? What?

By the way, my matched fets are 6.85mA Idss, if it has any bearing on the matter.

Many thanks
Lucas
Click to expand...


It will work OK at 9V too. 9.5-10.5V was just my subjectively preferred region. Don't know if you will hear any difference. Technically yours its correct too. The Leds can settle thermally to some different point each time. But do you know its not part DVM's tolerance as well? What is your DC on the filter caps? So to tell you about the Tx. And what is the DC offset in mV on audio outputs? Any picture?
 
K

korben69

Member
Joined 2006
merlin2069er said:
I've got a quick question regarding this BOM.

Transistors BC-550 B or C = 2
BC-517 G = 1

Are they all required, or is BC-517 G an alternate for the BC-550 B/C?

Thanks,
JG
Click to expand...

Yes both refs are required, you'll need :
1° - BC-560B or C - 1 unit (BC-556/7/8/9 are alternatives to BC-560B or C)
2° - BC-550B or C - 2 units
3° - BC-517G 1 unit (I'm using BC-517 without grade mentionned, depends on the manufacturer marking)
 
CeeVee

CeeVee

Member
Joined 2006
Paid Member
LucasAdamson

LucasAdamson

Member
Joined 2009
Salas said:
It will work OK at 9V too. 9.5-10.5V was just my subjectively preferred region. Don't know if you will hear any difference. Technically yours its correct too. The Leds can settle thermally to some different point each time. But do you know its not part DVM's tolerance as well? What is your DC on the filter caps? So to tell you about the Tx. And what is the DC offset in mV on audio outputs? Any picture?
Click to expand...


DC on the second filter cap is 18.1v DC - same on both channels.

How do I measure the output DC offset? Across the 1R resistors? I used jumpers, as I have no 1R resistors. Otherwise, I haven't made any substitutions or amendments to the design or parts.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
Your DCin-DCout is healthy. No need for a new Tx.

Offset is if you have made it as a full board including the audio part, to measure DCmV across the audio outputs, so we know its adequately safe, since there are no output DC blocking capacitors. Since this is not the regulator only thread its assumed you are making a full buffer pre. Or not? Also did you use your other positive only specialized 30V reg on your Atlantic phono by now?
 
LucasAdamson

LucasAdamson

Member
Joined 2009
Salas said:
Your DCin-DCout is healthy. No need for a new Tx.

Offset is if you have made it as a full board including the audio part, to measure DCmV across the audio outputs, so we know its adequately safe, since there are no output DC blocking capacitors. Since this is not the regulator only thread its assumed you are making a full buffer pre. Or not? Also did you use your other positive only specialized 30V reg on your Atlantic phono by now?
Click to expand...

Hi Salas,

I am still waiting on a few parts for the B1 end of things. Originally I wasn't going to do the delay, but in the end I am, so I am waiting for components.

I did use the other reg with the Atlantic phono, but unfortunately, it's a nice design built on the worst PCBs I've ever used (I think he makes PCBs for a living too??) The traces are incredibly fragile and I was getting only one channel due to ripping a whole trace off when unsoldering a connector. Honestly, it's like chocolate wrapper.

So, in my frustration, I decided to rebuild in point to point, which I've been doing all day today. It's my first p2p and it looks like a freaking mess, but is actually very neat, and fun! Give me a week! :)

Otherwise, thanks again for being awesome...
 
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