UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - What sort of output coupling Capacitor on a Ravensbrook

bikerhifinut · 29th Jun 2020, 12:40 pm

Rogers Ravensbrook series2.
The output is coupled to the speakers via 1500uF 30V DC wkg electrolytics.
I'm refurbishing this amp as most of the electrolytics are original and it seems sensible to do a full recap in stages, testing the amp as I replace each pair of electrolytics. Including a tidy up of my original PSU bodge done many years ago as an inexperienced youth................ It still works so I think i did ok it just looks scruffy. (I blew the pass transistor with an electric guitar cos the 1A quick blow fuse wasnt quick enough and Dad was not pleased! But I did get it going again)
I'm ok with the rest of the electrolytics, I'll use decent branded 63V devices even where some are rated at 6V as the physical size of modern stuff is much smaller. It does look to me like Rogers specified voltage ratings right on the limit as I guess back in the 60s the costs would have been very tight. The PSU voltage is regulated at 43V by a zener and pass transistor.
Anyway The output caps I am a bit unsure about, I figure they are rated right on the limit anyway but along with the working Voltage are there types that should be fitted here given that they are passing a sizeable current into the speakers? I'm thinking stuff like ESR etc. Or will a decent branded general purpose Capacitor be as good as it gets? These were pretty fine amplifiers back in the day and I do remember it being very good indeed and Dad said he chose the Rogers over the Armstrong/Leak/japanese competition based on its very neat and tidy construction on a single fibreglass pcb with components well spaced which to his non electronic eyes suggested a high quality construction. It certainly is nicer to work on than a lot of contemporary gear.
Thanks,

Andy.

29th Jun 2020, 12:40 pm	#1
bikerhifinut Octode Join Date: Nov 2013 Location: Penrith, Cumbria, UK Posts: 1,993	What sort of output coupling Capacitor on a Ravensbrook Rogers Ravensbrook series2. The output is coupled to the speakers via 1500uF 30V DC wkg electrolytics. I'm refurbishing this amp as most of the electrolytics are original and it seems sensible to do a full recap in stages, testing the amp as I replace each pair of electrolytics. Including a tidy up of my original PSU bodge done many years ago as an inexperienced youth................ It still works so I think i did ok it just looks scruffy. (I blew the pass transistor with an electric guitar cos the 1A quick blow fuse wasnt quick enough and Dad was not pleased! But I did get it going again) I'm ok with the rest of the electrolytics, I'll use decent branded 63V devices even where some are rated at 6V as the physical size of modern stuff is much smaller. It does look to me like Rogers specified voltage ratings right on the limit as I guess back in the 60s the costs would have been very tight. The PSU voltage is regulated at 43V by a zener and pass transistor. Anyway The output caps I am a bit unsure about, I figure they are rated right on the limit anyway but along with the working Voltage are there types that should be fitted here given that they are passing a sizeable current into the speakers? I'm thinking stuff like ESR etc. Or will a decent branded general purpose Capacitor be as good as it gets? These were pretty fine amplifiers back in the day and I do remember it being very good indeed and Dad said he chose the Rogers over the Armstrong/Leak/japanese competition based on its very neat and tidy construction on a single fibreglass pcb with components well spaced which to his non electronic eyes suggested a high quality construction. It certainly is nicer to work on than a lot of contemporary gear. Thanks, Andy.