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Post by puffin on May 20, 2022 7:47:03 GMT
Anyone here got one of these or heard one? I have just built one and for such a simple circuit and small parts count it is a really great sounding amp. !0w of Class A and you can tailor the sound with biasing the MosFets. Mind you I had some monster heat sinks and a nice case bought years ago when these things were just about affordable.
If anyone is intersted I can post a few pics.
Rob.
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Post by MartinT on May 20, 2022 8:27:44 GMT
Please do. I have a lot of time for anything that Nelson Pass designs.
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Post by tarzan on May 22, 2022 9:18:41 GMT
Yes please- would love to see some pictures.  |
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Post by puffin on May 22, 2022 15:14:50 GMT
Sorry for the delay. I had intended to take some less fuzzy ones, but have been sidetracked by replacing a large portion of a boundary fence whilst the weather is good. Anyway here they are. The Cambridge Pre below is just for adjusting a Sub volume when used.    |
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Post by MartinT on May 22, 2022 15:41:47 GMT
Dual toroids, dual regulated power supplies, by the looks of it. Where did you get the circuit boards from? Does it get appreciably warm when running?
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Post by puffin on May 22, 2022 16:19:20 GMT
Dual toroids, dual regulated power supplies, by the looks of it. Where did you get the circuit boards from? Does it get appreciably warm when running? It is in fact an unregulated supply giving out roughly 25/26vdc. The ACA can be run at 19vdc or 24vdc with an additional resistor added to the board. The IRFP240 Fets can take up to 200vdc so as long as the other components could take a higher voltage you can go higher. I know there is one builder who runs his at 48vdc. Given that Nelson Pass suggests 19 or 24vdc, then I would assume that he has found that these give the sound signature that he designed for. The amp gives around 8 - 10 watts dependant on the additional circuit tweak and 10 very fine watts they are IMO. You can tailor the sound to a degree by tweaking the gain with a variable resistor. The reccomended setting is roughtly half the full vdc, but some like it lower and some higher. I was gifted the boards and components by a mate a few years ago and thought that I had better get them built. |
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Post by puffin on May 23, 2022 6:08:12 GMT
I don't know about anyone else but I find I do my best remembering if I wake up at about 6am or often earlier. Mind you I have to carefully filter out all the rubbish that seems to invade the brain at these times. What I remembered today was that the ACA was designed to be a cheap and simple way for anyone to sample a Class A amplifier. Nelson Pass felt that SMPS PSs had improved so much over the years and were fairly cheap in the 19v or 24v power output that these were recommended for this application.
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Post by MartinT on May 23, 2022 7:46:34 GMT
I don't know about anyone else but I find I do my best remembering if I wake up at about 6am or often earlier. I've been like that all my life, do my best work from before 06:00 and start fading by about 15:00. |
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