Sorry Salas, yes 10K trimmer and 3R for R1.
Here is an interesting thing, when connected to the DCG3, one positive reg only puts out 4V DC. It also fluctuates slightly between 4 - 4.17V. No amount of adjustment will change the output.
Tested with and without a 120R load it works absolutely fine but when connected to the amp it fails.
I checked with the other pair of regs and the other positive reg works ok so it is definitely a problem with one positive side.
The 0V are linked together at the regs on each pair. The troublesome one is the inside right positive reg
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One has to feed the relay circuit also another the servo. See if it can't stand the full inrush demand as set for CC and limits. For 150mA DCG3 bias I would have used 2R or 1.8R R1 per reg. It can swing double its bias current on a demanding low Z headphone. 5.6R or 6.8R 1W or 2W per side piggybacked on each 3R will also do the trick for now.
Are the leds lit? I had the same problem. I had to increase CCma until reg could supply DCG3 and not shut down. That low voltage means it’s being overdriven. If you’ve got a lot of offset it will asymmetrically load the BiB and shut it down. Get offset dialed out and retry with CCma that is appropriate for your bias. 100+100+100 extra. The BiB can’t dump the extra current.
Cheers,
Greg
Good cheers Greg. Yes the leds are lit but very dim. Will try a 2R for R1 and retry.
I had to go to 600ma to get both regs to run properly when powering the DCG3. But I have big sinks. Again, get them both to run and then get the offset out and try again at an appropriate CCma.
Yes, just go slowly and get them to stay running. Then you will see proper rail voltage.
Meet up the zero returns of each Ubib pair at the DCG3's zero PSU points. Y style. Increase CC. There are local capacitors and extra circuits that will peak the current demand of the DCG3 at start up. Now you got circa 50mA spare current reserve only. Use 150mA shunt current even if for line use of the preamp. To have good startup, PSRR, and Zo from the regs.
Test first with handy resistors in parallel to R1. See also about rearranging the zero connections from the PSUs output connectors to the DCG3 channels power connectors as I described.
Yours is common PSU between channels so when I suggest 300+300 (with circa 2R R1) for his dual it computes. Have you got 7.5R bias resistors on your DCG3 too?
I just finished building this. When I switched on, R1 was smoking and very hot. R1 is 1.5R 3W and the transformer is 25Vac. I've isolated the rectifier circuit which is supplying about 28VDC. Strangely RF which is only 2W was not even hot which is in series to R1.
Not sure where to look next. I hope no damage to any components caused, but wonder if there are any particular components to check for failure.
Appreciate any offer of help.
Not sure where to look next. I hope no damage to any components caused, but wonder if there are any particular components to check for failure.
Appreciate any offer of help.
Salas and Greg, we are all good, many thanks. I should apologise the answers were in the thread when you look regarding a specific problem.
The only low ohm resistors I had were 3.3R 3W so parallel with 3R R1 we get around 1.57R = 382CCma . DCV across R1 is still 0.589.
17.25V at the DCG3 input, separate 0V's summed at the amp, all is well. Everything warms up nicely.
The only low ohm resistors I had were 3.3R 3W so parallel with 3R R1 we get around 1.57R = 382CCma . DCV across R1 is still 0.589.
17.25V at the DCG3 input, separate 0V's summed at the amp, all is well. Everything warms up nicely.
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Alright, handy value for a proof test. Congrats. Your initial 3R R1 choice would have probably been alright for a 100mA biased preamp. See it not to cold start above 18V regarding the warm up negative drift allowance so the servo chip will not see any long term rails exposure above its max spec. The now CC will make the regs assembly run hot so 0.59V/1.8R=0.327A is a good final target for your high bias I guess and its going to reduce the temperature as well. The 600/R1 mA formula from the guide proved alright in practice for the various builds tolerances also (~590mV in your four builds i.e. only -1.7% off). That's helpful in predicting CC setting resistors right value parts purchases securely.
BTW we now also realize how efficient the plug and play DCSTB dual mono solution for the DCG3 is but when we want the certain touch of shunt power we got to go the extra mile
BTW we now also realize how efficient the plug and play DCSTB dual mono solution for the DCG3 is but when we want the certain touch of shunt power we got to go the extra mile
Passive,
I like your BiB setup, nice work. I've got mine in a 2U, mounted like an amp board, so plenty of dissipation.
That's what the BiB seems to be, a Class-A amp being used as a power supply. I've powered three different pre boards with my single, mono BiBs, and its an awesome power supply.
Cheers,
Greg
I like your BiB setup, nice work. I've got mine in a 2U, mounted like an amp board, so plenty of dissipation.
That's what the BiB seems to be, a Class-A amp being used as a power supply. I've powered three different pre boards with my single, mono BiBs, and its an awesome power supply.
Cheers,
Greg
Trouble
Attached a simplified Schematic of an amplifier with C3M and 13e1se.
I replaced the cathode resistor/bypass cap of 13e1 with the 1.3 BIB.
One monoblock is running fine the first 15 minutes or so, wi music, then the 13e1 starts to oscillate. wiring between reg and cathode of 13e1 is ca 10 cm.
The other amp similar, but running without this issue.
13e1 160ma, 24v at cathode. Input to 1-3 reg is 22v Ac. R1 2,4 ohm
Suggestions ?
Attached a simplified Schematic of an amplifier with C3M and 13e1se.
I replaced the cathode resistor/bypass cap of 13e1 with the 1.3 BIB.
One monoblock is running fine the first 15 minutes or so, wi music, then the 13e1 starts to oscillate. wiring between reg and cathode of 13e1 is ca 10 cm.
The other amp similar, but running without this issue.
13e1 160ma, 24v at cathode. Input to 1-3 reg is 22v Ac. R1 2,4 ohm
Suggestions ?
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