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I'm new to amp mods. Can anyone tell me how to access the pre amp tube as I want to swap it for a lower gain tube. I tried unscrewing the four panel screws on the back but nothing moves!
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The back will come off,there is glue holding it in place,just take it off carefully and you will not damage anything.
I do not do mods myself,but just had a mod done on my Champ 600 yesterday,the tech jumped the built in Equalizer,and changed out the cheap Chinese tubes that were in there from the factory and put two older but great sounding tubes in place.
The two changes greatly improved the sound of the amp,it has a lot more volume now and sounds a lot more tone and is much more closer to the sound of the original Champ 600 amps.
I am not sure where exactly on the circuit board he jumped,and what he used for the jumper, but if any one wants to know any more information pertaining to the mod that was done,I could give him a call and get back to you.
This is my first post,and thank you so very much for letting me join this great forum. -
iIf you could find out where he made the EQ jump, I would be very interested. Thanks for the offer. I replaced the tubes, volume pot and speaker in my Champ 600, and it made a world of difference.Comment
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I had to bring the amp back to him , as it would work great for about an hour,then the volume would die,and hardly any sound would come out of it.
It was doing that before I brought it too him,so he wanted to keep the amp for a few days so he could troubleshoot the volume problem, and he was not to keen on the 1/4 watt resisters that they use on the board, so he was going to give the amp a complete check and overhaul, and replace any defective parts, and change what parts he thinks would help the amp.
I just got a set of JJ tubes today from Eurotubes today, they just came in the mail today, and he did not want me to put them in the amp until he found the problem,once it cools down it works good again for about an hour and the same thing happens.
Once he has it repaired and any new mods that he does on the amp,I will let you know as well as where he jumped the EQ and if he had to change it or left it in place.Comment
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Good luck with he repairs. I found that the volume pot that comr=es with the amp is VERY wimpy, and I replaced it with a real 1 Meg pot, as I was also having spotty volume loss. It will be interesting to see what your tech does. It would be a good idea to think about a better speaker for your amp, it can make a huge difference.Comment
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I found a mod on another forum that removes the fixed tone stack and makes the 600 more of a 5F1 circuit. It increases the overall volume and tweed sound by %100 . I also switched the tone cap from .022 to .1 and ended up with a fuller and in my opinion, bassier sound. I was also able to fit an 8" speaker into the cabinet with a nice Fender sparkle looking grill cloth. I am using a 12AY7 preamp tube so as to be able to use more of the volme control before feedback with my harp mics.
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