Salas hotrodded blue DCB1 build - Page 203 - diyAudio
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Old 13th July 2012, 09:10 PM   #2021
Renron is offline Renron  United States
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Big E,
I just bought a pair of these from Flea-bay yesterday after looking at ~ 45 pages of listings. I'm planning on cooking eggs on my IRFPs.

60*150*25mm Heatsink Aluminum Heat Sink for LED, Power IC Transistor, Module PBC | eBay

no affiliation with seller.
Ron
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Old 15th July 2012, 12:49 AM   #2022
jeff517 is offline jeff517  United States
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I want to use the DCB1 as a pre amp for a tube map I put together.
Do y'all think I can use the Tube amp with the potentiometer bypassed/jumpered? Wouldn't the B1 just pick up where the pot was jumpered? If so I could put them in the same case. Or should this be in tube forum?
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Old 15th July 2012, 01:00 AM   #2023
Salas is offline Salas  Greece
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You can do either but having the pre as a unit is more flexible than dedicating it. In any case skip the tube amp's pot when having DCB1 in the chain. Also consider the accumulating heat and hum fields when planning integration.
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Old 15th July 2012, 01:31 AM   #2024
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So how much heat we talking? The DCB1 is a mezmerize per BOM. And sheilding would help with hum?
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Old 15th July 2012, 01:43 AM   #2025
Salas is offline Salas  Greece
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If you run it low CCS<100mA we are talking just 1W dissipation per Mosfet. But it has to sit in a rather cool place of the chassis not to receive heat from power tubes also, away from power amp's trafo fields as it will be carrying input signal. Don't allow more than 50C in the vicinity of its electrolytics in a closed warmed up box. Ambient temp has to be calculated to the Mez's sink estimations also. Mezmerize is a full preamp up to 6 inputs, are you going to integrate multi input capability to the tube amp as well? Coax signal wire for sure. Going for a full integrated? Then you surely need to examine some tube integrateds to see how they shield, route, ground, etc. Its a complex job, but done many times.
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Old 16th July 2012, 02:39 PM   #2026
BigE is offline BigE  Canada
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Salas and Renron,

thanks for the recommendations!
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Old 16th July 2012, 05:50 PM   #2027
BigE is offline BigE  Canada
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I just checked the farnell site.

If the ebay heatsink is similar to the farnell that is listed with 25 mm fins, it won't have enough dissipation -- over 1.5 deg C/W.

I'll be sticking with the farnell, unless I can find something a bit closer to home.
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Old 16th July 2012, 08:08 PM   #2028
Renron is offline Renron  United States
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Big E,
I found a wonderful heatsink calculator for us laypersons. I don't speak engineerese.
Natural convection heat sink

I graphed the HS i referred to earlier for both 600mA (12W) and 200mA (4W)
You're going to need some BIG sinks for 600mA!
I guess I'll be running the VW Golf turbo (200mA) 10 Ohm version with my ordered HeatSinks.
This is without forced air circulation just convection cooling.

Ron
Attached Images
File Type: jpg 600mA heatsink.jpg (319.1 KB, 258 views)
File Type: jpg 200mA heatsink.jpg (161.9 KB, 241 views)
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Old 17th July 2012, 03:50 AM   #2029
BigE is offline BigE  Canada
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That calculator is smarter than me. I could not get it to reproduce the values for the farnell heatsink, so I'm not using it. It did show a 25 degree rise over ambient for the farnell sink though. Which is fine.

The farnell sink is HUGE! 100 x 100! I could make an amp case out of 4 of them, but adding volume and rca's is problematic.

So what are people doing for a case for such an item? I'm thinking thick aluminum plates added to front and back sides, heavy aluminum floor with L brackets and a ventilated top.

Last edited by BigE; 17th July 2012 at 03:59 AM.
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Old 17th July 2012, 05:49 AM   #2030
Salas is offline Salas  Greece
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Wanting 0.6A hot rod, what would you expect... 12W dissipation per rail constantly with a 15+15VAC Tx... Your box construction plan sounds good. You should use good thermal paste (even CPU special paste -non conductive-) between the Mosfets-their pads-sinks and then use again along the sink sides which will be bolted to the Alu chassis. Then between chassis plates meeting lines, so the whole thing is aided to act as a bonded thermal mass.
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