FWIW: Here are the heat readings taken after an hour with big music (M. LeGrand Big Band & Shostakovitch Sym #9) pushing the FSs at a fairly high level. Case is warm ~ 24 C, but nowhere near hot. Vent holes won't be necessary.
The 39 C is an anomaly - it's like a little black hole that is sucking in heat. Gonna have to watch more Discovery Channel.
Added the highly anticipated "Night Shots"
The 39 C is an anomaly - it's like a little black hole that is sucking in heat. Gonna have to watch more Discovery Channel.
Added the highly anticipated "Night Shots"
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Monoblock FE's
Got them built, sounding great already. Getting a low level hum though when connected to my DCB1, can't hear it when music is playing but can just hear it when nothing is playing. No time just now to have a play with them, too busy but will get back to it later. I'll try to post some of my usual bad quality pictures, wish I could get some reasonable photos taken, they actually look quite good though you wouldn't know it looking at these bloody awful efforts
Got them built, sounding great already. Getting a low level hum though when connected to my DCB1, can't hear it when music is playing but can just hear it when nothing is playing. No time just now to have a play with them, too busy but will get back to it later. I'll try to post some of my usual bad quality pictures, wish I could get some reasonable photos taken, they actually look quite good though you wouldn't know it looking at these bloody awful efforts
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Ah! The beauty of simplicity. Those look fantastic - very pro. I'm sure you will find a simple ground related glitch for that hum. I believe Dario is using a DCB-1. Your pictures are just fine. Let the music flow!!!!
BTW: That's the exact finish I'm trying to get on mine - only naked.
BTW: That's the exact finish I'm trying to get on mine - only naked.
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Thanks Bob!
I'm making roasted paprika chicken and roasted vegetables for us just now but when I've finished making a pig of myself, i'll have a go at moving cables around etc. It's all a bit of a tangle behind the rack at present. If I have no joy I might give Dario a shout to see what he can suggest. I connected the transformers copper screen's to the enclosure, I might try disconnecting them to see if it helps. It did with the chipamp.com LM3886 kit but then it's boards had their grounds connected to the chassis so it probably wont help. I noticed I'm getting switching noise from the attenuator when I adjust it so that might be a clue.
I'm making roasted paprika chicken and roasted vegetables for us just now but when I've finished making a pig of myself, i'll have a go at moving cables around etc. It's all a bit of a tangle behind the rack at present. If I have no joy I might give Dario a shout to see what he can suggest. I connected the transformers copper screen's to the enclosure, I might try disconnecting them to see if it helps. It did with the chipamp.com LM3886 kit but then it's boards had their grounds connected to the chassis so it probably wont help. I noticed I'm getting switching noise from the attenuator when I adjust it so that might be a clue.
A couple more inside pictures, both amps are identical.
I tried moving wires around and even disconnected the transformers screen but no use. The biggest improvement to the hum came when i changed the digital coax lead from my V-LINK to DAC to an optical one, still getting hum but not quite as loud. When i turn the volume up it gets really quite loud. Any suggestions folks?
I tried moving wires around and even disconnected the transformers screen but no use. The biggest improvement to the hum came when i changed the digital coax lead from my V-LINK to DAC to an optical one, still getting hum but not quite as loud. When i turn the volume up it gets really quite loud. Any suggestions folks?
I still have an issue between the DCB1 and the FE's, I cant use them together at all.
I tried feeding the DCB1 with an ipod which works ok just feeding the FE's. No use, still got hum issues.
At this rate i'll be scrapping an FE tomorrow so that I can put the system back to what I had before which worked very well indeed
I tried feeding the DCB1 with an ipod which works ok just feeding the FE's. No use, still got hum issues.
At this rate i'll be scrapping an FE tomorrow so that I can put the system back to what I had before which worked very well indeed
I went over the passive pre with my DVM, no fault showed up.
The only things I can connect to the FE's and them not have hum issues is a shorted out RCA phono plug or a battery powered ipod.
They have hum issues with EVERYTHING else.
I'm listening to headphones just now, DAC - DCB1 - Headphone amp. No problems just great sound.
Did you ever start something, then wish you hadn't bothered?
The only things I can connect to the FE's and them not have hum issues is a shorted out RCA phono plug or a battery powered ipod.
They have hum issues with EVERYTHING else.
I'm listening to headphones just now, DAC - DCB1 - Headphone amp. No problems just great sound.
Did you ever start something, then wish you hadn't bothered?
Does that mean you confirmed DC offset/output on the DCB1 is negligible when it is the end of the signal path?
Did you test with a simple bare pot as a substitute for the DCB1?
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I checked the passive unit for a ground break, pot imbalance or continuity problem, nothing showed up.
I tried feeding the FE's straight from my DAC which is double insulated with no earth connection in it's supply, still got hum. Even with the DAC feed by an optical link I still get hum. No time just now to do anything, I have to go out but i'll have a go later to see if I can sort this. The only things I can plug into the FE's and not get hum is a shorted phono plug and my ipod which I used to initially test the amp's.
I tried feeding the FE's straight from my DAC which is double insulated with no earth connection in it's supply, still got hum. Even with the DAC feed by an optical link I still get hum. No time just now to do anything, I have to go out but i'll have a go later to see if I can sort this. The only things I can plug into the FE's and not get hum is a shorted phono plug and my ipod which I used to initially test the amp's.
Hi Davy
Don’t despair
It’s going to be a small problem and once you’ve found it you’ll thing OH was that all.
I used my DC1B with no hum issues at all but I have both FE’s in one case with double transformers.
It seems that you may have a grounding issue from your description so let’s try to work through what might be causing it,
Could you humour me and try connecting up just one of your FE and see if the hum is still errr humming.
I usually tie my transformer screen straight back to the mains ground and tend not to connect it to the chassis so that may help a little but I’m sure it’s going to be something else.
Have you grounded your DC1B at the transformer IP end? If you have you may want to try having that floating so no centre tap to ground connection.
you could also try dropping all of the mains related cabling onto the floor of the chassis nice and close to the sides as you may be picking up hum from that.
I’m guessing that it’s going to be a small problem and so easy to fix so chin up you’ve done the hard part.
Don’t despair
It’s going to be a small problem and once you’ve found it you’ll thing OH was that all.
I used my DC1B with no hum issues at all but I have both FE’s in one case with double transformers.
It seems that you may have a grounding issue from your description so let’s try to work through what might be causing it,
Could you humour me and try connecting up just one of your FE and see if the hum is still errr humming.
I usually tie my transformer screen straight back to the mains ground and tend not to connect it to the chassis so that may help a little but I’m sure it’s going to be something else.
Have you grounded your DC1B at the transformer IP end? If you have you may want to try having that floating so no centre tap to ground connection.
you could also try dropping all of the mains related cabling onto the floor of the chassis nice and close to the sides as you may be picking up hum from that.
I’m guessing that it’s going to be a small problem and so easy to fix so chin up you’ve done the hard part.
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Hi all,
sorry, I've been a bit busy in the last days...
I've seen great builds and metal works!
Good job Bob and Davy!
Davy, I'm sorry you're having hum problems, it's probably due to some cabling/connectors problems but there are also some other possible problems.
Did you try to move a bit the input molex plug and its wires?
The hum is present at both monoblocks?
Which sensitivity have your loadspeakers?
When I've had similar problems in the past it was always something wrong with grounds on signal connection, polarity (signal and ground reversed) and so on.
Also, with high sensitivity speakers (from 94DB and up) a faint hum is present but can be greatly reduced grounding the heatsink to the board.
Also on your case, since the heatsink is part of the chassis maybe you can tame the hum connecting PGND to the safety earth bolt you have on the bottom panel of your case.
I would exclude a build problem on boards since you have no hum with input shorted.
BTW what are you using to short input? Post a pic if you can, please.
Don't discourage, we will sort this problem out.
sorry, I've been a bit busy in the last days...
I've seen great builds and metal works!
Good job Bob and Davy!
Davy, I'm sorry you're having hum problems, it's probably due to some cabling/connectors problems but there are also some other possible problems.
Did you try to move a bit the input molex plug and its wires?
The hum is present at both monoblocks?
Which sensitivity have your loadspeakers?
When I've had similar problems in the past it was always something wrong with grounds on signal connection, polarity (signal and ground reversed) and so on.
Also, with high sensitivity speakers (from 94DB and up) a faint hum is present but can be greatly reduced grounding the heatsink to the board.
Also on your case, since the heatsink is part of the chassis maybe you can tame the hum connecting PGND to the safety earth bolt you have on the bottom panel of your case.
I would exclude a build problem on boards since you have no hum with input shorted.
BTW what are you using to short input? Post a pic if you can, please.
Don't discourage, we will sort this problem out.
Thanks folks. If I get a chance later i'll try a few things.
Andrew - you could be onto something there.
shoom - my DCB1 is not connected 0v to chassis ground, I didn't have hum issues before so I left it like that.
Dario - Speakers are 6 Ohm 89db so medium sensitivity.
I'll try soldering the signal input wires to the boards and i'll try moving the mains wiring around, both amps are identical and both have the same issue so it'll be a wiring related problem - probably.
Will report back later on.
Davy
Andrew - you could be onto something there.
shoom - my DCB1 is not connected 0v to chassis ground, I didn't have hum issues before so I left it like that.
Dario - Speakers are 6 Ohm 89db so medium sensitivity.
I'll try soldering the signal input wires to the boards and i'll try moving the mains wiring around, both amps are identical and both have the same issue so it'll be a wiring related problem - probably.
Will report back later on.
Davy
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Dug into this winters first batch of home-made beef barley/vegetable soup (almost over the line to stew
) yesterday, and it knocked me out from 6 PM till 12:30 in the morning. So we are traveling two paths together.For your encouragement, here is a shot of my current configuration. It is hum free but it took a long time to determine the hum was from bad continuity at the FE PCB entry point - and a defective RCA socket. At some point I was convinced the problem was the DAC and/or the Pre, but simply wiggling wires identified the glitch. Hang in there!!
BTW; Shoom, I left the trani shields unconnected this time. Don't think I ever tried connecting them directly to the mains inlet ground tab. I'll give it a shot.
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Connect them to the point the AC Mains attaches to the chassis. Not directly to the ground lug of the IEC socket.
(I think that's what you were saying, but I wanted to clarify.)