Salas hotrodded blue DCB1 build

[Tea-Bag]

Try 1K output series resistors instead of 220 Ohm. Maybe you got instability in the interface to the actives.

Oscillation?

 

[Salas]

''Squeal'' is a suspicious term for possible oscillation.

 

[cersepn]

I guess the strange thing is that i didn't have the squeal when i first did up the DCB1, even with the active speakers.. That's why it's puzzling to me.

 

[cersepn]

Okay.. i tried to record the funny noise, could you guys check it out and tell me what you think? I'm wondering if it's a earth and grounding issue, is it possible? There's no 60/120hz hum though. Only that weird high frequency noise.
Memo.mp3

 

[Salas]

Could be oscillation, try 1k resistors as I wrote yesterday. You can try them in line with your output RCAs, no need to install them on the board in this test phase.

 

[lloop9]

Hiya fellows. Regarding the R-core transformers a few of you used. diyclub listed the R26-34 model as a 40W unit.

However, on Diygene, the same R26-34 is listed as 50W. Can anyone confirm the actual rating of said transformer?

Also, is this unit sufficient for a hot-rod build?

diyclub: DIYCLUB

diygene: 50W R Core Transformer,115V//230V, for Preamp,DAC/R26-x

 

[AndrewT]

The current ratings appear to be the same, 700mAac
After feeding a capacitor input filter the maximum continuous DC current is ~350mAdc

I recommend running the CCS at no more than 200mAdc

 

[lloop9]

Thank you for the advice Andrew. 🙂

 

[Atilla]

Hiya fellows. Regarding the R-core transformers a few of you used. diyclub listed the R26-34 model as a 40W unit.

However, on Diygene, the same R26-34 is listed as 50W. Can anyone confirm the actual rating of said transformer?

Also, is this unit sufficient for a hot-rod build?

diyclub: DIYCLUB

diygene: 50W R Core Transformer,115V//230V, for Preamp,DAC/R26-x

I'm using pretty much the exact same transformer with no issues. Just don't take too much current, as Andrew said.

 

[lloop9]

Thanks for your feedback Atilla

 

[Skywave-Rider]

Should the - of the unbalanced in/out be floating from the chassis?

 

[Nick77]

Just ordered a bunch of parts and supplier only had 20awg solid core hookup wire. I would normally buy 24awg for wireing signal connections, any problem using 20awg as signal wireing?

 

[igor0203]

Will this be sufficient for hot-rod? 600mA?

Dimension of heatsink are: 150x27x40mm [LxHxW]

 

[Salas]

Hmm, if it will be affixed to thick enough metal chassis with ventilation holes on top and bottom.

 

[igor0203]

Interesting, I thought those heatsinks will be overkill for 600mA.

 

[Salas]

What is their C/W rating?

 

[igor0203]

I could only found this:

At length 50mm: 1,7 C/W
At length 100mm: 1,3 C/W

 

[Salas]

Length of those you showed and your transformer VAC?

 

[igor0203]

Below is my heatsink drawing, width is 40mm. I'll use 50VA 15VAC transformer.

 

[Salas]

They will have to receive 12W each side constantly. If we assume they are 1.2C/W capable, that will mean +15C on ambient. In a box with 40C average inside after warm up, that will mean 55C on the fins. If the box is not ventilated well, soon its ambient will climb.