|   ADCOM power amps | eirepaul
Feb 15, 2001 10:33 AM | | I have two ADCOM GFA 555mkII power amps bridged to mono for each channel of my stereo system. The system sounds great, however there is a noticeable hum in the system that can be heard when no music is being played. Does anyone have any experience/suggestions with this? Does it affect the sonic resolution/performance of the system? It doesn't appear to, but I would still like to get rid of it. Thanks. |
| re: ADCOM power amps | Dread
Feb 16, 2001 10:29 AM | | Could be ground loops.
http://www.epanorama.net/documents/groundloop/index.html |
| re: ADCOM power amps | WackEmcee
Feb 18, 2001 9:51 PM | | The very first thing you should check on is the quality of your cables. I had a problem that was close to what you have and a better set of cables cleaned the problem right up. |
| re: ADCOM power amps | greyman
Feb 19, 2001 7:20 AM | | There could be others this as well. Larger transformers, in power amps can be additive to the hum. Also, DC offset, caused by dimmer switches in the same circuit as the amplifiers, as well a street lights can add to the problem as well. Is there hum in both channels or just one? Does it hum more at night? Also, is there any power conditioners/regenerators involved with the system? The ground loop scenario can be tested by lifting the ground with a two prong cheater plug. |
| re: ADCOM power amps | eirepaul
Feb 19, 2001 10:13 AM | | Thanks for the replys. I am finding the ground loop link particularly useful. The hum is in both channels, not worse at night, no line conditioner used. I will be moving some cables around and trying a few different combinations. I'll let you know how it goes. Thanks again. |
| re: ADCOM power amps | rick riley
Feb 19, 2001 5:55 PM | | i had a similar problem when i had adcoms but they blew soon after the hum started and i got pair of brystons which are bulletproof and so transparent. have since heard similar stories from other (former) adcom owners. btw, adcom is just an aggressive marketing co., not a quality component mfr. |
| You're not much of a help, Rick (nt) | Norm Strong
Feb 19, 2001 7:39 PM | | |
| re: ADCOM power amps | eirepaul
Feb 20, 2001 10:10 AM | | Yeh, really Rick. Thanks, a lot for your uhh... input. I know where ADCOM equipment is at, but it suits me fine and I am happy with the sound in my system. All I need is some constructive help on eliminating the hum. How can you "blow" these amps anyway? |
| re: solved the problem | eirepaul
Feb 21, 2001 9:29 AM | | I solved the problem last night. One of the power amps has a 2-prong power cord and one has a 3-prong cord. I used a 3to2 prong adapter plug on the one amp and the hum/buzz went away. It was apparantly a ground loop problem. I bought the amps at different times hence the power cord difference. Adcom changed from one to the other at some point. |
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