Bonzo Posted November 6, 2010 Share Posted November 6, 2010 I have been using a mostly restored Scott 299c for some time. It is a great amp but I do have one complaint. There is a low but audible hum on both channels. Does not increase or decrease with volume it's just there. Not to say it drives me a bit crazy but, it does! I stumbled accross a "box stock" Fisher X-100-3 integrated amp. A friend of mine picked this up with a bunch of other tube stereo stuff. It was in great physical shape but the tubes were a bit tired. I had some very good 12AX7's but not the 7189 power tubes. Fortunately my friend is lousy with tubes and I bought an NOS quad of Military GE 7189A's for a great price. I have never been a huge fan of EL84 amps but this little Fisher sounds SOOOO GOOD! Dead quiet, plenty of bass, warm mids and mellow highs through the vertical Corns! It is certainly giving the Scott some competition and, did I mention the Fisher is dead quiet! I have a combination of Telefunken and Amperex 12AX7a's accross the front that are obviously a great match. Just thought I would share my Fisher story. Any other Fisher fans out there? Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Here's another pic. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Topless or bottom less? Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Pot(s) dude! Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Love those Military tube boxes, "One Each"................ Quote Link to comment Share on other sites More sharing options...
Frank1938 Posted November 6, 2010 Share Posted November 6, 2010 Nice looking amp and easy to work on. You may want to have the 299c checked. My 299B and my 299D never had a hum. Frank Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Hello Frank,there are about eight original caps that I am going to have a friend of mine replace. They are .1's/400 V that may be the issue? My fear is the issue may be the power transformer as it is an equal hum through both channels. Regarding the Fisher, I was amazed to find that much open space underneath! In addition to the Scott, I have had a couple of old Sherwoods where real estate was very hard to come by. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 6, 2010 Share Posted November 6, 2010 Bonzo, No those .1uf caps are not going to be the source of your low level hum. In most cases if you have a low level hum equal out of both channels it will be power supply related heater and/or high voltage. A hum out of one channel could be a coupling cap, tube or just about anything. But those .1uF caps should absolutely be replaced. The Fisher amps are nice but even it will sooner or later give you troubles if you keep running it. Running 50 year old amps in original electrical condition is a bit wreck less and asking for trouble IMHO. In my experience that's how transformers end up going up in smoke. Craig Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Thanks for the info. Craig, I appreciate it! I just noticed the power transformer in the Scott has a hum as well. I hope that doesn't mean what I think it means? Some of the guys over on AK think it is not long for this world. Good news is I got cheap as non-working. The original owner tried 6U8's when it was pinned for 7199's! It didn't work, go figure. I haven't noticed the transformer hum before but it could have been there in addition to the hum through the speakers. Here's some pics. (SORRY TO GO OT ON MY OWN THREAD) Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Oh, it has been re-wired for 6U8's. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted November 6, 2010 Author Share Posted November 6, 2010 Top. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 7, 2010 Share Posted November 7, 2010 Eeerrrrrr this forum! I wrote a long reply with suggestions as to what may be the problem , hit post and the forum did not respond... lost my post. In short the amp is well worth getting working properly and should be a simple but maybe hard to track down problem. Heck its 90% rebuilt and looks to be a nice condition 299C! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.