It works on such a voltage also. Its still within sane dissipation limits for the BL range JFETS. With mains powered regulator supply I liked it at about 10V little better but with batteries I don't know the subjectives. The chemical type for its electrical properties may again play a little tonal role or not. Rather more than the 14V rail voltage level I would suspect.
hey guys!
i have a question concerning the DCB1 + F5 amp. I just finished my F5 amp, but when I connect both inputs with the DCB1 I can hear a buzz on one of the two channels. When I connect only one input I can't hear a noise, also when I connect the input of the F5 with ground I hear nothing.
So, when I used the DCB1 with my SymAsym amp I did not hear any buzz. The only difference I see at the moment is, that there is a CL60 between mass and casing in the F5 and no resistor between mass and casing for the symasym.
So, am I right that there is no resistor between the case and the DCB1 mass as well, and that's why I have a problem? Has somebody had the same problems with dcb1 + f5? Any ideas? thanks a lot!
i have a question concerning the DCB1 + F5 amp. I just finished my F5 amp, but when I connect both inputs with the DCB1 I can hear a buzz on one of the two channels. When I connect only one input I can't hear a noise, also when I connect the input of the F5 with ground I hear nothing.
So, when I used the DCB1 with my SymAsym amp I did not hear any buzz. The only difference I see at the moment is, that there is a CL60 between mass and casing in the F5 and no resistor between mass and casing for the symasym.
So, am I right that there is no resistor between the case and the DCB1 mass as well, and that's why I have a problem? Has somebody had the same problems with dcb1 + f5? Any ideas? thanks a lot!
OK, thanks salas! But now i have to ask a silly question, but it qust came into my mind now.
In post #4 I can see the schematic of the DCB1. There is the analogue ground AGND and the ground of shunt (has no name). Those two are connected via the jumper J2 but there is normally no connection between this AGND and the case, thus the EARTH-signal (yellow/green), right?
That's exactly where i maybe have to place my NTC/resistor what ever?
In post #4 I can see the schematic of the DCB1. There is the analogue ground AGND and the ground of shunt (has no name). Those two are connected via the jumper J2 but there is normally no connection between this AGND and the case, thus the EARTH-signal (yellow/green), right?
That's exactly where i maybe have to place my NTC/resistor what ever?
That is central place you can have access to the dcb1 ground route yes. Tie its chassis there and see if it may help with your new amp situation. In general mating this buffer pre with F5 amps was very popular and I dont think I remember buzz complaints so it should be solvable. Its some kind of system groundloop most probably. Can't predict if it will answer the problem since its not analyzed but its easy to do and see. Make sure any metal part of the volume pot will be on the same ground too.
Happy new year all,
On the topic of grounding, I too have a couple questions about the best grounding strategy for my setup. I've had a very slight buzz through my loudspeakers which I assumed was EMI but after cleaning up some wiring and doing a bit of troubleshooting, I now believe it is a ground loop.
My DCB1 (which is running marvelously otherwise I might add) is being used as a switch/buffer for a few of my components and feeds both a headphone amp as well as my power amp. I will try and describe the signal flow:
- 2 sets of inputs go to a source selector switch, which then feeds a volume pot, which finally feeds the input of the DCB1
- 2 sets of outputs. One is fed by a passive split off of the source selector switch to run my headphone amp (thus monitoring what I've selected with the switch), and the other is fed by the DCB1 output.
What would you suggest as the best strategy to use for connecting the various signal grounds, e.g., input and output jacks, switch, volume pot, and DCB1 i/o, together?
On the topic of grounding, I too have a couple questions about the best grounding strategy for my setup. I've had a very slight buzz through my loudspeakers which I assumed was EMI but after cleaning up some wiring and doing a bit of troubleshooting, I now believe it is a ground loop.
My DCB1 (which is running marvelously otherwise I might add) is being used as a switch/buffer for a few of my components and feeds both a headphone amp as well as my power amp. I will try and describe the signal flow:
- 2 sets of inputs go to a source selector switch, which then feeds a volume pot, which finally feeds the input of the DCB1
- 2 sets of outputs. One is fed by a passive split off of the source selector switch to run my headphone amp (thus monitoring what I've selected with the switch), and the other is fed by the DCB1 output.
What would you suggest as the best strategy to use for connecting the various signal grounds, e.g., input and output jacks, switch, volume pot, and DCB1 i/o, together?
Hi Salas,
By "hp amp" I assume you mean the power amp, and no, the ground loop is no longer audible when I disconnect the DCB1 and add shorting plugs to the power amp. In troubleshooting I have also removed all of my other equipment so that all that remains is the DCB1->power amp, and the ground loop is audible, whether or not the DCB1 is powered.
By "hp amp" I assume you mean the power amp, and no, the ground loop is no longer audible when I disconnect the DCB1 and add shorting plugs to the power amp. In troubleshooting I have also removed all of my other equipment so that all that remains is the DCB1->power amp, and the ground loop is audible, whether or not the DCB1 is powered.
I meant removing the headphone amp. But you also replied you tried the power amp + DCB1 only and that covers it.
Are there any references of signal ground to chassis either in the DCB1 or the power amp? Like wires from PCBs to chassis? Are there protective mains earth wires from IEC third prongs to those chassis?
Are there any references of signal ground to chassis either in the DCB1 or the power amp? Like wires from PCBs to chassis? Are there protective mains earth wires from IEC third prongs to those chassis?
Thanks for the quick replies Salas,
I just broke out the multimeter and tested continuity between chassis ground and signal ground for all my components (between ground lugs of AC input and ground on RCA jacks). Seems that all my components except the DCB1 have continuity between chassis ground and signal ground (indicating a reference somewhere). Should I tie the chassis and signal ground in the DCB1?
I just broke out the multimeter and tested continuity between chassis ground and signal ground for all my components (between ground lugs of AC input and ground on RCA jacks). Seems that all my components except the DCB1 have continuity between chassis ground and signal ground (indicating a reference somewhere). Should I tie the chassis and signal ground in the DCB1?
You should experiment with this but if not productive you could also experiment with safe loop breaker in the power amp Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
Unfortunately there's no difference when I add a reference between chassis and signal ground in the DCB1. Hrm, this is perplexing. I really wonder if it has to do with the signal grounding scheme within the DCB1.
Can you advise as to the best practice for connecting the signal grounds of the input and output RCAs, the volume pot, and the DCB1 i/o?
Can you advise as to the best practice for connecting the signal grounds of the input and output RCAs, the volume pot, and the DCB1 i/o?
Its very rare we had ground loop discussions in the DCB1 threads. Surely nothing inherent, it should be fixable. Better upload an inside photo of your particular build so we have an idea of how its done.
measure the output Hum+Noise when the power amp has shorting plugs in all inputs.
Then add on the DCB1 one channel only and measure H+N
Then add on the other DCB1 channel and measure the H+N
Then add on one channel of source and measure H+N
Finally add on the second channel source and measure H+N
That way you will find which interconnect increases the H+N.
Then add on the DCB1 one channel only and measure H+N
Then add on the other DCB1 channel and measure the H+N
Then add on one channel of source and measure H+N
Finally add on the second channel source and measure H+N
That way you will find which interconnect increases the H+N.
Check that the power amp's PSU connections to boards, bolts on reservoir caps poles if any, chassis ground lugs, are firm.
Thanks for the assistance guys. I'm amazed how committed you remain to this thread over the years and hundreds of pages 
Andrew, while I have not measured the noise, I can tell you this:
-Shorting plugs on power amp input = zero noise
-Connecting the DCB1 (with no sources connected) adds the buzz/noise to corresponding connected channels.
-Disconnecting the input to the DCB1 (on the PCB) adds some white noise, but I can still hear the offending buzz in there as well.
-Adding subsequent sources makes no change.
Here is a pic of the DCB1 build. I realize it's not the tidiest thing ever... Very limited space (and somewhat limited skills)...
EDIT: okay, not sure why I didn't do this before, but I tried plugging one of my sources (phono preamp) directly into my power amp, thus presenting the power amp with a load but taking the DCB1 out of the equation altogether... and... the noise remains. I think it's safe to say the issue is with the power amp. Bummer... Thanks again folks
Andrew, while I have not measured the noise, I can tell you this:
-Shorting plugs on power amp input = zero noise
-Connecting the DCB1 (with no sources connected) adds the buzz/noise to corresponding connected channels.
-Disconnecting the input to the DCB1 (on the PCB) adds some white noise, but I can still hear the offending buzz in there as well.
-Adding subsequent sources makes no change.
Here is a pic of the DCB1 build. I realize it's not the tidiest thing ever... Very limited space (and somewhat limited skills)...
EDIT: okay, not sure why I didn't do this before, but I tried plugging one of my sources (phono preamp) directly into my power amp, thus presenting the power amp with a load but taking the DCB1 out of the equation altogether... and... the noise remains. I think it's safe to say the issue is with the power amp. Bummer... Thanks again folks
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