Post your Solid State pics here.

[martinbls]

Originally Posted by tinitus

Ok, bridge mounting also caught my attention, but being a picture thread I didnt comment
But now you are at it, bridge mount does look dangerous
If it gets loose and turns just a bit, the bridge housing could touch the neg/pos, and short the rails

Anyway, 15A bridge isnt that much really, I have always used 35A bridge

You're absolutely right about that!

But, first of all, the heat conducting pad would always ensure a small gap between the rectifier and the pcb traces (there is of course a hole in the centre of the pad where the centre bolt gets through, so it wouldn't slip out of place if the bridge would turn around), and secondly I used both a nut AND a, well, I don't no the english word for it, "safety nut"?, to ensure that a loosening of the nuts is almost impossible.

But as said, I would agree, one has to be very careful with those things to make sure that such a unit is made with long term reliability in mind! Those are the small but important details... ;-)

[EBM_dude]

Do you mean "selbstsichernde Mutter" with "safety nut"? Then it's a self-locking nut. I had to use google to find that out....

[martinbls]

Originally Posted by EBM_dude

Do you mean "selbstsichernde Mutter" with "safety nut"? Then it's a self-locking nut. I had to use google to find that out....

Yes! That's exactly what I meant.
Thank you!

[lanchile]

Originally Posted by martinbls

Yes! That's exactly what I meant.
Thank you!

I would not worry about it if they are safety nuts that you are using. But I would worry about those caps attach to the cabinet. I hope you use some kind of good glue or silicone. I use caps like those too but I used a lot of high strength silicone. it looks ugly but better safe than sorry. beside after I close the enclosure of my amp ......nobody will see what is inside lol.

[martinbls]

Well, I wasn't aware about this going so deeply into details, but yes. Beside the centre bold there are round pads of a very strong double-sided tape at the bottom of each cap to prevent the whole cap bank from moving and vibrating.

[lanchile]

Originally Posted by martinbls

Well, I wasn't aware about this going so deeply into details, but yes. Beside the centre bold there are round pads of a very strong double-sided tape at the bottom of each cap to prevent the whole cap bank from moving and vibrating.

lol. Do not worry. This is all because your amp looks so neat and professional build that we are looking for something to say lol. just look mine and you see it is a mess and nobody said nothing hehehehehehehe. Again your amp looks awesome!.Congratulations.

[martinbls]

Originally Posted by lanchile

lol. Do not worry. This is all because your amp looks so neat and professional build that we are looking for something to say lol. just look mine and you see it is a mess and nobody said nothing hehehehehehehe. Again your amp looks awesome!.Congratulations.

Hey lanchile,

thank you for those kind words! You see, this isn't my first amp, and with every new project one goes a bit deeper into such details. And even though I'm still far away from the level of professionality of some other members of this forum, I certainly do enjoy building such things, and this is what you can see.
Your amp looks quite good as well, and the most important factor of all this is of course proper funktionality, reliability and GOOD SOUND!! And especially the last aspect doesn't have much to do with neatly bended wires...

But since you did build a LM3875 amp too, perhaps you might be interested in my DAC/AMP consisting of a Peter Daniel NOS-DAC and a stereo LM3875 amp.

Chip Amp Photo Gallery

Just scroll down the page a bit.

Kind Regards!
Martin

[lanchile]

Originally Posted by martinbls

Hey lanchile,

thank you for those kind words! You see, this isn't my first amp, and with every new project one goes a bit deeper into such details. And even though I'm still far away from the level of professionality of some other members of this forum, I certainly do enjoy building such things, and this is what you can see.
Your amp looks quite good as well, and the most important factor of all this is of course proper funktionality, reliability and GOOD SOUND!! And especially the last aspect doesn't have much to do with neatly bended wires...

But since you did build a LM3875 amp too, perhaps you might be interested in my DAC/AMP consisting of a Peter Daniel NOS-DAC and a stereo LM3875 amp.

Chip Amp Photo Gallery

Just scroll down the page a bit.

Kind Regards!
Martin

Very nice again!. your LM3875 from peter Daniel looks awesome.
I agree with you 100% with "it doesn't have much to do with neatly bended wires" because it can look nice and neat but if it sounds bad...it is waist of time,wires and money lol. if it sounds good and looks good ...it is a job well done!.

[jacco vermeulen]

Originally Posted by martinbls

Further more

Martin,

i'm somewhat surprised that a bridge rectifier can be cooled sufficiently with only a few square inches of clad board.
By the looks, the available cooling surface is roughly twice the area of the rectifier block : 2 * 1.2 sq in.
The copper on the clad board has zero thermal inertia, plus only the top side of the copper exchanges heat with ambient.
Rough estimate for an equivalent heatsink would be in the order of 40-50 C/W.
Add an Rjc of 1.5-1.9 for each diode, plus 1C/W for Rca, results in an average dissipation of the bridge rectifier of less than 3W.

For the bridge rectifier, two 50W channels are a near equivalent load as a single 200W power amp.

[martinbls]

Hi jacco,

yes, but the maximum power rating of such an amp is nothing more than a worst case cenario. The average power for listening to music in a quite small living room with quite sensitive speakers is only a few watts per channel, and even that is not continuous. And even if music is played loudly for a long time period, it consists of many short impulses, rather than a continuous signal. So, I'm pretty sure that I could go even for a 10A bridge without any cooling at all without running into heat problems. Another thing is that many diy'ers use discrete diodes on small pcb's even for much larger power amps with no added extra cooling than the backside of the TO220 or TO247 cases. Even in such cases, I've never heard of heat problems with rectifier diodes.
That means, the idea of adding an extra bit of cooling surface by using the heat conducting pad and a few square cm's of thin copper surface is just because the whole design asked for it (due to the components placement), and not because I felt this to be needed.

But anyway, thank you for your advice and the calculations!

Regards!
Martin