Note that I caveated the 27R a few posts back:
Your points regarding practical implementation are, as usual, greatly appreciated. See, we even agree on the cap value! A heavy duty bridge does seem sensible and practical.
Your points regarding practical implementation are, as usual, greatly appreciated. See, we even agree on the cap value! A heavy duty bridge does seem sensible and practical.
That safe lift looks very similar to that posted on Elliot Sound Products page, with the exception of the resistor value. For reference, here is a link to the entire Elliot Sound Products grounding article.
http://sound.westhost.com/earthing.htm
http://sound.westhost.com/earthing.htm
Of course. I just edited the values as by Beck's recommendations. You can see 'esp' on top left of the picture I posted.
Sorry Salas, wasn't meaning to point the finger or anything... Just thought I recognised the diagram (my eyes did not see the esp logo). When I checked the esp page, I thought that the information there might be of interest to you and others following he thread.
Cheers,
Chris
Cheers,
Chris
No worries mate. We just diy and we try to put concepts together for all to benefit from. No sages here. Had this drawing in my hard disk, Beck was describing just that but with different decoupling values, I posted it fast. Came handy. Its about safety, and a picture catches the eye. Its because SY and Beck contributed a very important note on safety.
Honestly I think people put way more thought into grounding than whats really needed. We're talking audio here, not microwaves. I've built various amps over the years with the same basic design. An aluminum plate with a wooden base and used the plate for a ground. No fancy star grounds or bus bars. Just grounding the components at the nearest available point. Just about every piece of commercial tube equipment was made that way, from dirt cheap AA5 radios to McIntosh and Marantz. The only hum problem I ever had was floating filaments on an SRPP stage. Bypassing one side to ground with a cap cleared it. And if you're still reading then thanks for listening to this rant. 
Special hum problems and ground loops I almost never get. But whenever I had rewired under a specific and well thought out ground scheme, the depth of image and resolution has appeared unmistakably stronger, and the tone softer. The gremlin is there if with a sloppy ground. It shows in IMD if it isn't strong enough to noticeably intrude on medium sens speakers. The amp I am rebuilding had zero hum and the faintest hiss with ear touching the dust cap or when placed 1cm within tweeter on a 95dB sens speaker. Precaution is about not laying out again with some obvious mistake when it can be predicted. As for just using the nearest chassis contact for any component with a ground arrow on the schematic, and then firing up and hearing no hum or zzz, this is crossing the avenue with an Ipod and reading Penthouse mag. It can be crossed some times but not always. There is a Mack coming head on at a point.
Jinx! Minor G. Loop.
Did the amp. Sounds great. But I get a minor ground loop. Some zzzz, not that bad but its there. Followed our bus bar scheme. See how it finally looks like in the attached picture. If I plug one channel out, the amp is silent as a tomb. Both channels in, same low zzzz on both channels. If I break one input coax shield with a 10R, I get the broken earth channel buzzing louder than before but the other channel becomes quiet. Lifted the mains earth on amp, preamp, source. Nothing. Its between L&R meeting in the amp. Ideas of what to change?
Did the amp. Sounds great. But I get a minor ground loop. Some zzzz, not that bad but its there. Followed our bus bar scheme. See how it finally looks like in the attached picture. If I plug one channel out, the amp is silent as a tomb. Both channels in, same low zzzz on both channels. If I break one input coax shield with a 10R, I get the broken earth channel buzzing louder than before but the other channel becomes quiet. Lifted the mains earth on amp, preamp, source. Nothing. Its between L&R meeting in the amp. Ideas of what to change?
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Why do you guys use a ground breaker circuit?
I've never had a problem just strait grounding it, when grounding at the input side of the buss. Even when connecting grounded sources. The only time groundbreakers have been usefull is in car audio, or when forced to ground at the power supply end of the buss.
Please share your knowledge🙂
I've never had a problem just strait grounding it, when grounding at the input side of the buss. Even when connecting grounded sources. The only time groundbreakers have been usefull is in car audio, or when forced to ground at the power supply end of the buss.
Please share your knowledge🙂
astouffer said:
Wait a minute. Investing in a sound ground busbar system is definitely worth the trouble, especially if one uses any form of high speed switchmode power unit (which I do) in the big power game.
For over 40 years in amp designs I have always used a closed earth loop concept and it works. Pic of 3.5mm bus interconneced in grid form shown for 2x150W stereo using parallel o/p pairs. With this closed bus one can be rest assured that both sides will perform symmetrically with excellent 15Khz separation performance at full power and hum isn't an issue.
Using a chassis with tags, they nearly always work loose.
richj
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If you still have hum after using the grounding sequence SY suggested earlier, then grounding most likely isn't the problem.
Post a schematic if you have one.
That's good if you have had luck with not paying much attention to grounding. I've found it to be quite critical (to an extent) in most amps i've worked on. It is mostly critical for single ended stages that don't have any common mode rejection.
Post a schematic if you have one.
That's good if you have had luck with not paying much attention to grounding. I've found it to be quite critical (to an extent) in most amps i've worked on. It is mostly critical for single ended stages that don't have any common mode rejection.
Jeb-D. said:
I have zero hum. I have minor zzzz when L&R inputs are connected. Dead quiet when only one input is connected.
Looking at the drawing you posted in #29 shows something of potential concern. You show the coax going from the jack of each channel, to the input of each channel, then to ground buss.
Do you have the ground of each coax going to the ground of the fist stage first, or were you just implying the signal only?
If you grounded each channels coax to the input of each stage first, that can cause a loop when both channels are plugged in. The coax ground of each channel should connect to the buss at the end thats grounded. This should also be the point where your first stage of each channel should be grounded as well.
Just remember your source most likely has the commons of each channel tied together at the output. So there should be no circuitry grounded between the point where the ground conductors of the two coax cables join. Otherwise that part of the circuitry will be in the loop.
If you get desperate try disconnecting one end (at the RCA jack side) of a single channels coax ground conductor.
Also, you may want to consider putting a grid-stopper resistor on the input of the first tube.
Do you have the ground of each coax going to the ground of the fist stage first, or were you just implying the signal only?
If you grounded each channels coax to the input of each stage first, that can cause a loop when both channels are plugged in. The coax ground of each channel should connect to the buss at the end thats grounded. This should also be the point where your first stage of each channel should be grounded as well.
Just remember your source most likely has the commons of each channel tied together at the output. So there should be no circuitry grounded between the point where the ground conductors of the two coax cables join. Otherwise that part of the circuitry will be in the loop.
If you get desperate try disconnecting one end (at the RCA jack side) of a single channels coax ground conductor.
Also, you may want to consider putting a grid-stopper resistor on the input of the first tube.
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