Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TerryD on July 20, 2014, 04:13:09 pm
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I changed my power caps on the 66 vibrolux. I also changed the electrolytics on the board as well. It sounds great and even newish but maybe not better. I also changed one .1 capacitor that a certain fellow says always to get rid of...a big chocolate drop looking type cap. The amp is tighter and brighter but is that always good? All the electrolytics were replaced with 25 mfd as per specs. Now dig this. this is what my old ones read at. The first three caps are double cap cans. Reading from the normal channel moving towards reverb channel/right to left:
1. 35.6
2. 37.3
3. 36.5
4. 37
5. 0 =no reading=Can that be and still run?
6.0 again from this double can
7. 35.3
I was contemplating just putting these back. but maybe that shouldn't happen? Any thoughts?
Terry
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In my opinion you're probably better off with the new electrolytics. They have a limited lifespan. The brown caps also tend to decompose and sound horrible in the process. When you say the amp is tighter and brighter, do you also notice a general tonal improvement? What rectifier tube is in this amp? There may be an alternative that sags a bit more which softens the attack. Like a NOS 5V4? I installed one of these in a similar amp that previously had a 5AR4, and found that it made the amp less harsh when cranked in the house, but it also didn't cut as well with a full band. Did you rebias after the cap change and are the voltages higher now?