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Old 17th April 2010, 04:30 PM   #7761
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Quote:
Originally Posted by HaflerFreak View Post
I will most certainly be auditioning a pair of 1990 MG2.6/R's on a F5.

Rated for 87dB sensitivity and 4.7 ohms, I cannot imagine the ribbons will disappoint with an F5, I hear the top-end is supernatural on the F5 - that is also how I could describe those foil ribbons - what a match!
I hope so. I have a pair of them and am just starting to build an F5 for dedicated use on the foil ribbons. Bypassing the passive crossovers was the first step. And I still have trouble believing how big a difference that made. The F5 looks to me like a really good choice for the ribbons. At least I am going to find out. Crossover point is about 750 Hz and impedance is aprox. 3.2 ohms. And they are far more efficient than the bass panel. If this works out as well as I hope it does, then I will have to find the complimentary amplifier for the bass panels. Which I don't want to think about yet. But those are a whole different animal. I suspect that will ask for maybe 200 Watts into 4 Ohms to get all of the goodness out of those. Perhaps less now that the passive crossover isn't taking its tax on the supplied power.

Last edited by Macronaut; 17th April 2010 at 04:33 PM.
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Old 17th April 2010, 05:10 PM   #7762
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Quote:
bobo, that will not make an efficient heatsink for a large size like is needed in this amp.
I do not agree.
This is only a matter of scaling.
For instance, stack 6 plates 0.2cm x 40cm x 15cm,
spaced by 5 plates 10cm x 15cm x 0.5cm.
Bolt them firmly using white goo.
Use them as two sides of the casing.
It will do.
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Old 17th April 2010, 08:14 PM   #7763
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maybe... there needs to be sufficient fin area, and sufficient spacing between the fins to permit proper air convection minus the losses between the layers... I think it needs to be bigger and more layers... if the losses between the layers are not too bad.

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Old 17th April 2010, 08:47 PM   #7764
tinitus is offline tinitus  Europe
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Like this maybe
Attached Images
File Type: jpg Køleprofil.JPG (16.8 KB, 652 views)
File Type: jpg Køleprofil 2.JPG (18.2 KB, 649 views)
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Old 19th April 2010, 04:37 AM   #7765
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Hi,

I make layout for my F5 board, please help me to check this layout, assuring there is no faulty on it. I havent edit the SK370 layout, the correct one is reverse it. Also about the thermistor, its better if placed near output transistor.

Thanks before
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Old 19th April 2010, 06:41 AM   #7766
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Click the image to open in full size.

i am wondering, there is +24 -24 and Gnd after CRC, the picture shown above don't connect anything to Gnd after crc, is it no need to connect the Gnd from crc to the Gnd of F5 board??

here is mine.
Click the image to open in full size.


i have a bunch of stupid questions, hope you all don't mind

my transformer used is E transformer which lead out 18 0 0 18, in before i am too stupid to connect both 0 0 together and into the Gnd of the CRC, and smoke coming out from the wires :O so end up i don't connect anything to both 0. Or is it wrong anything?
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Last edited by chchyong89; 19th April 2010 at 06:47 AM.
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Old 19th April 2010, 08:18 AM   #7767
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chchyong89;
On mine the F5 ground goes to speaker negative and input negative only, CRC ground goes to chassis earth, 18 0 to 1 rectifier and the other 18 0 to other rectifier with the 2 positive outs of rectifier joined together to CRC + and same with - from rectifier, hope that makes sense.
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Old 19th April 2010, 08:30 AM   #7768
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Psu (CRC) ground is connected to F5 board.(Green wire)
Generally, the outputs of a transformer are 0-18-0-18 and not 18-0-0-18.
To check, connect the two presumed 0 together and then measure voltage across the two 18. You should read 36v. As long as you do not short a winding, there is no risk.
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Old 19th April 2010, 09:27 AM   #7769
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(sorry my last post should read ) input negative and CRC ground goes to chassis earth,
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Old 19th April 2010, 10:46 AM   #7770
AndrewT is offline AndrewT  Scotland
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never experiment with transformer connections without a mains bulb tester feeding the primary.
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