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Old 10th July 2010, 01:28 AM   #1691
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Quote:
Originally Posted by Salas View Post
You use too small sinks for 10R set resistors, luckily those Mosfets are war dogs.
When they'll land in the case they will be bolted to the alluminum bottom plate, could this be enough?
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Old 10th July 2010, 01:31 AM   #1692
Salas is online now Salas  Greece
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By all means. Imagine it copes with now situation. Just don't run it too long for the time being. Nice careful build by the way.
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Old 11th July 2010, 11:42 AM   #1693
Malka07 is offline Malka07  England
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Yesterday i hotrodded my dcb1...i added a 5w 10ohm resistor to the 1w 68r resistors...giving me when measured 7.9ohm
2.04v/7.9 = 258ma
1.73v/7.9 = 218ma

Wow what an improvement!!! The soundstage has opened up wider and deeper, i am hearing sounds all around me(yes sounds even coming from behind me!!!). As a result i can tell where singers or instruments are very easily, and can even differentiate between backing singers. Now this is what i call Holographic. Detail has also gone up a notch and sounds more dynamic, yet the music never grates, i just want to keep on listening....BUT...

After listening for about 30mins (Yes i could tell all the above with just 30mins of listening!) i checked to see the temperature on the mosfets, by touching them with my finger, OUCH way too hot cant touch it very long before it burns, so i took out some heatsinks from an old computer powersupply that doesnt work and listen again for about 30mins, this time the temperature of the mosfets are cooler then before but still too hot, and there is no way im going back to 60ma after hearing it at circa 200ma!!! So i take out the 12v fan from the computer power supply and connect it to an unused 12v tap on the small toroid. After another 30mins of listening i checked the temperature of the mosfets and they are cool

Next up i will install the fan into the cover of the chassis, and i will try the salas shunt reg to run the Optivol

Special thanks to Salas, Nelson Pass and all who participated to make the DCB1 possible
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Old 11th July 2010, 02:05 PM   #1694
Ryssen is offline Ryssen  Sweden
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Would be nice to know if theres a limmit (the current) where it starts to sound better,and if itīs an upper limmit where it donīt sound any better..
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Old 11th July 2010, 04:21 PM   #1695
AndrewT is online now AndrewT  Scotland
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could you hear any difference on the high CCS current whether the FETs were too hot or cool or very warm?
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Old 11th July 2010, 06:06 PM   #1696
Malka07 is offline Malka07  England
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Hi Andrew, yes i do remember at the time thinking, that they sounded better when the fan was on them, but if it really was better, it would of been a very minimal improvement, maybe cleaner sounding, but not as big an improvement as going from 60ma to 240ma. I should also state that before i went up to 240ma i went to 80ma and did notice an improvement, but again it was slight, but it did improve with the soundstage increasing in depth and width and sounds seeming to float in the room, again more of a 3d sound just not to the extent of going up to 240ma.

Alon
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Old 11th July 2010, 06:20 PM   #1697
udailey is offline udailey  United States
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F5 uses same transistors.. 1.3A !!
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Old 11th July 2010, 06:28 PM   #1698
Malka07 is offline Malka07  England
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Quote:
Originally Posted by udailey View Post
F5 uses same transistors.. 1.3A !!
Hmmmm thats got me thinking...How high can i take the current without them getting hot, while the fan is on them

Guess im gonna have to experiment

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Old 11th July 2010, 06:43 PM   #1699
Salas is online now Salas  Greece
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Those Mosfets still amaze me with their ruggedness. So tiny sinks and they survived. Didn't I tell to use proper sinks or bolt to thick floor so many times? You can't run on same sinks you use for regular setting a hot rod. OK, killing a Mosfet is no big deal, but if someone uses a DC amp without output relay DC sense, bye bye speakers. OTOH, when prepared rightly the anti environmental setting attitude has some subjective benefits.
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Old 11th July 2010, 07:04 PM   #1700
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Hm. I have 10 ohm Mills for my hot rod. So if I try out 6 or 6.5 ohms, that would make for a sizable increase in mA. Enough to make a noticeable difference I imagine?

I assume 5 ohms is the lowest one should go?
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