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09-18-2018, 07:27 PM
Hi Kevin,
I've brought it up to clipping and then backed off slightly to just before clipping and that was when I got 55 watts or so, before power scaling was added to the amp. That was at 480V B+. Power scaling steals a little bit of voltage so if I remember correctly it was around 470V with power scaling added, and I never did check the power output with power scaling on it, but it might be a hair less.
In the RCA manual for a pair of 7868's, they list 44 watts for a 6k6 load, so the 3k3 sounds about right. Its been several years since I did this, but I think I measured the OT at a 2k5 load, but I could be wrong on that. For Va and Vs under full load....I'll have to get back to you. It might be awhile until I get to this as I've been working on a long term car repair for my former daily driver and once I find a couple hoses I can put it back together finally. Working on it outside and trying to beat the winter weather, and will be out of the country for a couple weeks in October so I'm running out of time to get that done.
I am curious why the power is lower than I would expect on this amp though so I will update with that info when I have it. I was thinking it was the transformer set and the capabilities of them/size of them. I have another CHB100 that I was going to experiment with down the road and was possibly going to get the transformers analyzed too depending on what I find out.
Thanks for the assistance!
Greg
I've brought it up to clipping and then backed off slightly to just before clipping and that was when I got 55 watts or so, before power scaling was added to the amp. That was at 480V B+. Power scaling steals a little bit of voltage so if I remember correctly it was around 470V with power scaling added, and I never did check the power output with power scaling on it, but it might be a hair less.
In the RCA manual for a pair of 7868's, they list 44 watts for a 6k6 load, so the 3k3 sounds about right. Its been several years since I did this, but I think I measured the OT at a 2k5 load, but I could be wrong on that. For Va and Vs under full load....I'll have to get back to you. It might be awhile until I get to this as I've been working on a long term car repair for my former daily driver and once I find a couple hoses I can put it back together finally. Working on it outside and trying to beat the winter weather, and will be out of the country for a couple weeks in October so I'm running out of time to get that done.
I am curious why the power is lower than I would expect on this amp though so I will update with that info when I have it. I was thinking it was the transformer set and the capabilities of them/size of them. I have another CHB100 that I was going to experiment with down the road and was possibly going to get the transformers analyzed too depending on what I find out.
Thanks for the assistance!
Greg
