What about these ones:
Kerafol 70/50 TO-247 Warmtegeleidende folie voor halfgeleiders 0.25 mm 1.4 W/mK Geschikt voor TO-247 | Conrad.nl
Next day delivery for me, as I am living in The Netherlands (diyaudio store will take 4 weeks unfortunately, so for consumables no option. However, it is great that they sell complete packages, pcb’s, and all other rare things. I love the diyaudio store, don’t get me wrong).
Use Keratherm (and support this site), or Kerafol. With these material you don't have to put thermal compound on it. With mica (also more fragile) you have to do that.
The metal plate of the power fets are electrical connected to the Drain pin. So, if not isolated from the heatsink, you connect the Drains of both fets together. For the F6, you connect in that way +24V to the speaker line, and the R4 doesn't like this. And you can destroy the lower fet also. And in the case the heatsink is connected to ground, you short circuit +24V.
Ceramic Alumina insulators are very good, and reusable.
Ceramic insulator plates 10 pieces for TO-3P / TO-247 good heat conductiviy ! | eBay
Ceramic insulator plates 10 pieces for TO-3P / TO-247 good heat conductiviy ! | eBay
Some good recommendations and respected manufacturers named for sure but dont let that distract you from troubleshooting. Any insulator designed for the job will do for now and probably long term. You can order keratherm from the store and swap it later and use whatever is locally available in the meantime but doesnt mean it is the only option.
Hello eddyvb,
Thank you for the clear explanation, this is very helpful for me!
Regards,
Koos
Theoretically you would feed the input of amp #1 a signal that is in polarity and the input of amp #2 one that is out of polarity. Then connect the speaker load across the two positive output terminals. Input polarity can be inverted with either an active circuit or an isolation transformer. That is the way most pro amps that share a common power supply work. Not sure about mono blocks.
What you cannot do to accomplish this is invert the input polarity of the Jensen transformer primary on the main PCB, because it is used as part of the negative feedback circuit.
Not sure what bridging would do the the remarkable sound character of this amp. I suspect it might not be worth the extra power. Remember, the F6 requires a lot of preamp voltage, so if your monoblocks sound "weak", and you are not clipping the amp, try a hotter preamp that swings more voltage.
OK , terminology is important , when trying to make a distinction between different things
as far as I know - Kerafol is name of company , while Keratherm is name of the product line/family
Kerafol is also used as brand designation , so you can find , for instance - at Conrad site - plenty Kerafol (name starts with thingies) ...... and just few Keratherm mentions - on the face of things , but if you dig a little - everything is Keratherm
though , there are different Keratherm products ......... KERATHERM<sup>(R)</sup> Heat conducting films
Actually, what the store sells, and what mostly is referred to when people here speak of "Keratherm", is the 86/82 variant:
Search results | Conrad.com
Best regards,
Claas
Search results | Conrad.com
Best regards,
Claas
transformer voltage
hi, i make the pass f6 and i got 2 toroidal 322 va at home but the secondary voltage is 24 volts secondary ,do you think that i can use this transformers so its 6 volts excess.If i use resistor to drop voltage maybe not a good solution and it takes 20 watts resistor its big enough .thanks for your help
hi, i make the pass f6 and i got 2 toroidal 322 va at home but the secondary voltage is 24 volts secondary ,do you think that i can use this transformers so its 6 volts excess.If i use resistor to drop voltage maybe not a good solution and it takes 20 watts resistor its big enough .thanks for your help
If you do go for mono blocks, and are using either chassis from store or other chassis with two heatsinks, one heatsink is unused.
Soooo, why not do what another member in another thread did. Buy a second set of DIY store Pass clone boards for another First Watt clone and load them into vacant spot?
The above mentioned other member then used stout switching to direct power supply to amp of choice. (With everything powered down of course.)
I'm about to do this with my M2 and Aleph J clones.
Russellc
18 volt rails?
In an earlier post, Zen Mod suggested that a 3U mini dissipante chassis with 400mm heatsinks would be on the verge of acceptability. Since my speakers are 4 ohm, I should have a few volts to spare. Could I conserve some heat by running +-18 volts instead of 24? Would that pose any other problems?
Thanks for any assistance.
In an earlier post, Zen Mod suggested that a 3U mini dissipante chassis with 400mm heatsinks would be on the verge of acceptability. Since my speakers are 4 ohm, I should have a few volts to spare. Could I conserve some heat by running +-18 volts instead of 24? Would that pose any other problems?
Thanks for any assistance.
18Vdc as lowest acceptable , for me , regarding mosfet bad behavior in capacitance domain ....... those are becoming unsteady when voltage goes down
so - either 18Vdc rails , or Babysitter
do what's easier
edit:
and yes , Jim is right
my remark about 3U was more probably for "regular" DiyA case - 300 deep
3U/400 is better than 4U/300
so - either 18Vdc rails , or Babysitter
do what's easier
edit:
and yes , Jim is right
my remark about 3U was more probably for "regular" DiyA case - 300 deep
3U/400 is better than 4U/300
I've been considering a monoblock F6 build in the 2U X 300 deep chassis with one of the two output mosfets moved off the PCB and over to the other heatsink. Figuring 0.31 for the 4U X 300 vs 0.225 for the 2U X 300 (1/2 of the 0.45 rating) it is theoretically even better.
But by the time you de-rate the heatsink for one transistor mounted on such a proportionately wide heatsink, they are probably about equal. Just my SWAG.
Hey, Im interested in the capacitance multiplier as used for voltage drop (as you suggested). I've not seen such a circuit for that purpose so if you can elaborate that would be great. It would help to explain how scale the voltage drop.