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PostPosted: 01 Dec 2019, 06:14 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I made two stereo amps for another member over ten years ago. I liked the Holton 200W amps so much I bought a pair of Holton nxv500 modules start the time. Only recently made the amp with them which sold in a few days. Sounded excellent. New owner lives it with my “Grace” tube preamp.

But originally I made this massive PS on a sub-chassis - 625VAC tranni with 80,000uf of 100V caps. But the PS would not fit. I made a smaller one with 40,000uf of caps and completed the amp.

To use the big PS I bought Holton’s latest 300W (500W into 4ohms) amp modules which use dual die lateral FETs - ECW20N20. These FETs have a negative temp. co-efficient and can take 200V at 16A each. This time I could not get the heat sinks required. The amps works well and sounds totally unbelievable but I have a heat issue. I’m going to turn the amp into two 300W monoblocks and with two new 150W modules use this heatsinks to make a 150W Holton amp.

Images and more to follow.

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Projects: "Precision" - 300W Class AB Holton power amp | "retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp |


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PostPosted: 01 Dec 2019, 06:35 
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Some images

https://holtonprecisionaudio.com/

http://www.exicon.info/why-use.php

http://www.exicon.info/products.php


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Projects: "Precision" - 300W Class AB Holton power amp | "retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp |


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PostPosted: 03 Dec 2019, 02:24 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I placed a silent fan I had been using under the amp inside and to the side so it blew across the back of the power FETs. It dropped the temp dome to 38 -> 45C with the lid on. Perfect. The fan can’t be heard even standing over the amp. I’ll shock mount it so it will be even quieter.

No need to turn it into monoblocks now. But I’m still going to build the 150W version. I have all the parts including a 300VAC 45-45V Tranni and 16 X 10,000uf 100V caps and enclosures just waiting amp modules.

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Projects: "Precision" - 300W Class AB Holton power amp | "retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp |


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PostPosted: 06 Dec 2019, 05:08 
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Prior to this one (and currently making another 150Wer) I made this one. 500 W modules but much earlier ones. Do not have the dual die lateral FETs. Only 40,000uf of caps as I wanted to fit everything inside the 3U enclosure so a skinnier PS required.
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Projects: "Precision" - 300W Class AB Holton power amp | "retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp |


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PostPosted: 06 Dec 2019, 05:10 
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Attachment:
59114FA5-0EC5-491A-A57A-025588ABD6A9.jpeg


Here is a PS I just finished today for the 150W version of the Holton amp.


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Projects: "Precision" - 300W Class AB Holton power amp | "retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp |


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