Luckily it doesn't happen too often.
I built up 4 amps and the first one didn't work. Turned out a resistor from Farnell was wrong despite packet having right resistance on it. Farnell didn't want to know, they just said they would inspect the bin and fix it if wrong. So all 4 amps were wrong and dneeded the resistor de-soldering and replacing in each.
I haven never had a wrong component from RS Components in 15 years although I have had missing components from the order from them.
Just one more small question
I have this buzzing from the mains transformer which is typical 50 Hz virbrations and since it is directly mounted on a 8 mm thick aluminium plate laying on a wood box it seem that I have built a nice 50 Hz horn, so I wonder, is it possible to slip in sum rubber between the transformer and alu plate to minimize the buzzing or will it not help that much?
I have this buzzing from the mains transformer which is typical 50 Hz virbrations and since it is directly mounted on a 8 mm thick aluminium plate laying on a wood box it seem that I have built a nice 50 Hz horn, so I wonder, is it possible to slip in sum rubber between the transformer and alu plate to minimize the buzzing or will it not help that much?
Those who subscribe to my newsletter or follow Neurochrome on Facebook know already, but I thought I'd made it more widely known that I have decided to discontinue the DG300B once the current board stock runs out. I'm spread too thin and have decided to focus on my solid-state designs. I have 15 DG300B board sets left. You can find them here: Neurochrome DG300B Product Page.
Tom
Tom
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Ok, where do I begin looking??
Last week I noticed that one of the two 300B tubes was not warming as the other one and a day or two later when I did put the amplifier on I got really nasty sounds coming through the speakers. The gastly sound is starting when the 300B tubes are connected after the driver tubes. First I thought that I had a tube that was gone but since the gastly sound is coming from both channels I don't think that is the case but then, where do I start looking cause there is absolutely something wrong here and it came very fast whithout any warning from one day to the other.
I don't have any device to measure the tubes but hope they are ok.
Anyone who can deliver a qualified guess where to start looking?? PSU, input stage, driver stage/bias or output stage?
Voltage to the 300B tubes are ok and both connect at the same time from the driver stage. Bias is ok on both channels.
This is the first time I have experienced anything like this so I really don't know where to look.... and for what so any help is appreciated!
Last week I noticed that one of the two 300B tubes was not warming as the other one and a day or two later when I did put the amplifier on I got really nasty sounds coming through the speakers. The gastly sound is starting when the 300B tubes are connected after the driver tubes. First I thought that I had a tube that was gone but since the gastly sound is coming from both channels I don't think that is the case but then, where do I start looking cause there is absolutely something wrong here and it came very fast whithout any warning from one day to the other.
I don't have any device to measure the tubes but hope they are ok.
Anyone who can deliver a qualified guess where to start looking?? PSU, input stage, driver stage/bias or output stage?
Voltage to the 300B tubes are ok and both connect at the same time from the driver stage. Bias is ok on both channels.
This is the first time I have experienced anything like this so I really don't know where to look.... and for what so any help is appreciated!
If the tubes bias up correctly and all the voltages check out, my best guess is that you're looking for a loose connection.
I don't understand what you mean by "the ghastly sound is starting when the 300B tubes are connected after the driver tubes". Without the 300B there's nothing to drive the output transformer so you'd get no sound in the speaker.
Tom
I don't understand what you mean by "the ghastly sound is starting when the 300B tubes are connected after the driver tubes". Without the 300B there's nothing to drive the output transformer so you'd get no sound in the speaker.
Tom
Have now checked for loose connections and bad solders for two weeks plus and turned upside down on everything without any result.
As I described before I notice that one of the 300B tubes is not heating as it should and since the change came very suddenly (over night), how would one single tube failure affect the output from the amplifier? Could one faulty 300B tube be the answer to this ghastly sound presented in both channels (witch seem too fluctuate at about 50 Hz) or should I look into grounding issues??
Problem is I don't have extra 300 B tubes so it has to be bought new but I have driver tubes if someone would surgest that it could be driver tube problem but driver tubes heat up as normal so my first guess is the 300 B tubes, any other surgestion?
As I described before I notice that one of the 300B tubes is not heating as it should and since the change came very suddenly (over night), how would one single tube failure affect the output from the amplifier? Could one faulty 300B tube be the answer to this ghastly sound presented in both channels (witch seem too fluctuate at about 50 Hz) or should I look into grounding issues??
Problem is I don't have extra 300 B tubes so it has to be bought new but I have driver tubes if someone would surgest that it could be driver tube problem but driver tubes heat up as normal so my first guess is the 300 B tubes, any other surgestion?
Ok, it has taken long time and what should I say, just didn't get my thumbs out and life came jumping on me!
I hav went back to the build document and started all over, going through voltages, regulators and everything I could think of (bad connections and so on). Everything is just spot on and I can't find anything that deviate from the documents so my conclusion is that the tubes are behaving, not the way I want to!!
Is there anyway that i can check the tubes without special tools (tester)??
I have driver tubes in spare but not any 300B tubes so I am stuck! And out of ideas (to little experience with electronics)!
I hav went back to the build document and started all over, going through voltages, regulators and everything I could think of (bad connections and so on). Everything is just spot on and I can't find anything that deviate from the documents so my conclusion is that the tubes are behaving, not the way I want to!!
Is there anyway that i can check the tubes without special tools (tester)??
I have driver tubes in spare but not any 300B tubes so I am stuck! And out of ideas (to little experience with electronics)!
As both channels show the same problem something must be wrong with the power supply. Even if one of the electrolytics (assuming there are more than one) has failed you may still get correct voltages but with a severe hum. It's unlikely the problem is with the 300B's then you would expect only one channel
not functioning well and not both.
not functioning well and not both.
Ok, after the last fixing and messing around inside the Damn Good 300B it is behaving normally again, playing music without disturbing noise BUT, and this is a big BUTT, I don't really know what has changed.
Or, somewhere I have definitely had a bad connection, most likely in the power distribution but I can not tell exactly where. When I checked the filament regulators I disconnected the cables entirely so it can be there but I am not really shure cause I have gone through all cables and screws seeing so that I had secured full tension on all screws. Some screws I have been able to tighten upp a 1/64 to a 1/32 turn but nothing more but it appear that somewhere it has helped. Sorry for bothering all of you, but big thanks that you have been willing to help.
I am now going to run this amp for a week and then go through it once again to recheck and then I will enjoy music again! Thank you all!!
Or, somewhere I have definitely had a bad connection, most likely in the power distribution but I can not tell exactly where. When I checked the filament regulators I disconnected the cables entirely so it can be there but I am not really shure cause I have gone through all cables and screws seeing so that I had secured full tension on all screws. Some screws I have been able to tighten upp a 1/64 to a 1/32 turn but nothing more but it appear that somewhere it has helped. Sorry for bothering all of you, but big thanks that you have been willing to help.
I am now going to run this amp for a week and then go through it once again to recheck and then I will enjoy music again! Thank you all!!