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Post by sometrolls2 on Feb 23, 2008 3:38:19 GMT
In the UK, I haven't got any versions of those and want to avoid mis-matching like 4A 100V with 3A 80V.
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Deleted
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Post by Deleted on Feb 23, 2008 3:51:32 GMT
sometrolls2 We are talking about a headphone amplifier with maximum current and voltage WAY below the capabilities of either type, provided there is adequate heatsinking. Basically, you need to select replacements with similar ratings, as well as Ft and typical current gain. You should be able to get suitable types locally, unless you live in a small town ? We use the 2SA1930 and 2SC5171 Toshiba devices in these applications, because they are superb devices,and have no problem getting them , either locally, or from Ampslab.. The audible difference may not be readily obvious. Incidentally, these devices are only rated for 2A,with a HFE of 100-320, and Ft of 200MHZ SandyK
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leo
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Post by leo on Feb 23, 2008 11:01:44 GMT
If you have a local Maplin try them, they used to stock the BD139/140
I'm afraid I don't have any left or I would have sent you some The Toshiba devices I used are what I had spare in my stock from a Audiolab amp repair
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FritzS
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Post by FritzS on Feb 23, 2008 13:20:39 GMT
sometrolls2 We are talking about a headphone amplifier with maximum current and voltage WAY below the capabilities of either type, provided there is adequate heatsinking. Basically, you need to select replacements with similar ratings, as well as Ft and typical current gain. You should be able to get suitable types locally, unless you live in a small town ? We use the 2SA1930 and 2SC5171 Toshiba devices in these applications, because they are superb devices,and have no problem getting them , either locally, or from Ampslab.. The audible difference may not be readily obvious. Incidentally, these devices are only rated for 2A,with a HFE of 100-320, and Ft of 200MHZ SandyK An interesting game ;D ..... compare Kumisa III + JLH PSU with "green Solo" and with "Mr. Doudou - Singer" ----- shops for Toshiba in Europe rockgrotto.proboards39.com/index.cgi?action=display&board=barry&thread=1203774864
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leo
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Post by leo on Feb 23, 2008 15:26:36 GMT
sometrolls2 We are talking about a headphone amplifier with maximum current and voltage WAY below the capabilities of either type, provided there is adequate heatsinking. Basically, you need to select replacements with similar ratings, as well as Ft and typical current gain. You should be able to get suitable types locally, unless you live in a small town ? We use the 2SA1930 and 2SC5171 Toshiba devices in these applications, because they are superb devices,and have no problem getting them , either locally, or from Ampslab.. The audible difference may not be readily obvious. Incidentally, these devices are only rated for 2A,with a HFE of 100-320, and Ft of 200MHZ SandyK An interesting game ;D ..... compare Kumisa III + JLH PSU with "green Solo" and with "Mr. Doudou - Singer" ----- shops for Toshiba in Europe rockgrotto.proboards39.com/index.cgi?action=display&board=barry&thread=1203774864If I get chance to hear a Singer I will do
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Post by sometrolls2 on Feb 23, 2008 23:42:03 GMT
Any chance of a group buy for some JLH boards?
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Post by Deleted on Feb 24, 2008 0:02:57 GMT
sometrolls2 We would have to standardise on a layout first, and them manage to put it in a format that the PCB makers can use. Allan is presently playing around with a much smaller PCB than mine. If you saw the original JLH article, you would see that our boards are very different to the original, partly due to having +VE and -VE supply versions on the same PCB. (Did I send you the original article ?) The downside of Allan's 2" x 21/2" version is that it is so small, that if you made a mistake, you are likely to cause damage trying to repair it. I also have reservations about the thickness of the supply line traces. Let's see what Allan and Leo have to say? Alex
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