Salas hotrodded blue DCB1 build - Page 205

BigE · 18th July 2012, 08:35 PM

Is there any issue with adding wiring so that the mosfets reach the heatsinks?

I've only seen designs that have their heatsinks bolted directly to the mosfets that are soldered to the PCB. My enclosure will be just wider than 90mm to accomodate the transformer.... Other designs have shown the mosfets bolted to the base plate of the enclosure -- are they hotrodding like that?

brainf · 07:24 AM

Quote:

Originally Posted by BigE

Is there any issue with adding wiring so that the mosfets reach the heatsinks?

I've only seen designs that have their heatsinks bolted directly to the mosfets that are soldered to the PCB. My enclosure will be just wider than 90mm to accomodate the transformer.... Other designs have shown the mosfets bolted to the base plate of the enclosure -- are they hotrodding like that?

Mine are wired with short lengths of magnet wire. No problems

BigE · 19th July 2012, 10:48 AM

Thanks! I'd guess the only issue would be potential for noise, especially with stranded wire.

Salas · 19th July 2012, 02:11 PM

That is oscillation potential territory. Extending is adding inductance, at least solder the gate resistor with very short pin to the gate -after- any attempted extension cable, and restore continuity with a jumper where the resistor was on PCB. Was not intended like that, nor scoped like that, grey zone.

BigE · 03:01 PM

Thanks!

The issue for mounting monster heatsinks and transformer in a box are mechanical --the 80 va transformer is over 90mm wide and bending the pins on the mosfet is not enough to make them reach the sink with a box that is 90mm wide internally.

So, instead of fins sticking out from the surface of the box, the box can be made larger by making the fins flush or in the same plane as the sides of the box. The footprint of the enclosure can be thought of as a barbell or dog-bone. The heatsinks may be bolted directly to the floor and become the middle front and back side of the enclosure.

One end now has enough room for the transformer.

--------------------------------------

If the pins of the mosfets can be bent to reach the heatsinks which are at the sides of the board and bolted to the top/bottom of the enclosure, then all problems are solved.

If the pins can't be bent, then a thick 10mm aluminum bar needs to be added as a heat spreader, though I worry about the thermal efficiency losses.

Siberia · 21st July 2012, 02:17 PM

No rest for me. I'm experiencing something I can't grasp control off. Low frequency attenuation is back three months later after the fix. It's a recurring problem, that was curred in different ways earlier. This time I'm more certain it's a DCB1 problem. A passive, two mono attenuators based pre shows more slam and bass and overall better balance in lows.

Checking connections, soldering, usual procedures since yesterday.

Siberia · 21st July 2012, 04:46 PM

You wouldn't guess what has worked for me. Cleaning both sides of pcb. I live in ex industrial area and building. It's quite dusty here and the pre was still in an open case. The underside collected dust as it was sticky after cleaning with isopropyl alcohol from last time. Wiped good as I could and voila.

Salas · 21st July 2012, 04:48 PM

(!)

BigE · 23rd July 2012, 07:25 PM

Picked up the transformer today! Potted 80 VA from Sumr in Toronto.

Now to order the heatsinks and the rest of the parts. Then, either make a box -- or stuff it into rectangular aluminum tube, a la Peter Daniel.

heatsinkusa looks like the best source.

pinnocchio · 23rd July 2012, 08:03 PM

Quote:

Originally Posted by BigE

Picked up the transformer today! Potted 80 VA from Sumr in Toronto.

Now to order the heatsinks and the rest of the parts. Then, either make a box -- or stuff it into rectangular aluminum tube, a la Peter Daniel.

heatsinkusa looks like the best source.

80VA for a DCB1? A bit big. I believe that ~25VA is sufficient. Anyways, it can't hurt if you use the right fuse!

Do

19th July 2012, 02:54 PM	#2045
BigE diyAudio Member Join Date: Aug 2008 Location: Toronto	Thanks! The issue for mounting monster heatsinks and transformer in a box are mechanical --the 80 va transformer is over 90mm wide and bending the pins on the mosfet is not enough to make them reach the sink with a box that is 90mm wide internally. So, instead of fins sticking out from the surface of the box, the box can be made larger by making the fins flush or in the same plane as the sides of the box. The footprint of the enclosure can be thought of as a barbell or dog-bone. The heatsinks may be bolted directly to the floor and become the middle front and back side of the enclosure. One end now has enough room for the transformer. -------------------------------------- If the pins of the mosfets can be bent to reach the heatsinks which are at the sides of the board and bolted to the top/bottom of the enclosure, then all problems are solved. If the pins can't be bent, then a thick 10mm aluminum bar needs to be added as a heat spreader, though I worry about the thermal efficiency losses. Last edited by BigE; 19th July 2012 at 03:01 PM.

21st July 2012, 02:17 PM	#2046
Siberia diyAudio Member Join Date: Feb 2011 Location: Vilnius	it's back and not kicking No rest for me. I'm experiencing something I can't grasp control off. Low frequency attenuation is back three months later after the fix. It's a recurring problem, that was curred in different ways earlier. This time I'm more certain it's a DCB1 problem. A passive, two mono attenuators based pre shows more slam and bass and overall better balance in lows. Checking connections, soldering, usual procedures since yesterday.

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18th July 2012, 08:35 PM	#2041
BigE diyAudio Member Join Date: Aug 2008 Location: Toronto	Is there any issue with adding wiring so that the mosfets reach the heatsinks? I've only seen designs that have their heatsinks bolted directly to the mosfets that are soldered to the PCB. My enclosure will be just wider than 90mm to accomodate the transformer.... Other designs have shown the mosfets bolted to the base plate of the enclosure -- are they hotrodding like that?

19th July 2012, 10:48 AM	#2043
BigE diyAudio Member Join Date: Aug 2008 Location: Toronto	Thanks! I'd guess the only issue would be potential for noise, especially with stranded wire.

19th July 2012, 02:11 PM	#2044
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	That is oscillation potential territory. Extending is adding inductance, at least solder the gate resistor with very short pin to the gate -after- any attempted extension cable, and restore continuity with a jumper where the resistor was on PCB. Was not intended like that, nor scoped like that, grey zone.

21st July 2012, 04:46 PM	#2047
Siberia diyAudio Member Join Date: Feb 2011 Location: Vilnius	You wouldn't guess what has worked for me. Cleaning both sides of pcb. I live in ex industrial area and building. It's quite dusty here and the pre was still in an open case. The underside collected dust as it was sticky after cleaning with isopropyl alcohol from last time. Wiped good as I could and voila.

21st July 2012, 04:48 PM	#2048
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	(!)

23rd July 2012, 07:25 PM	#2049
BigE diyAudio Member Join Date: Aug 2008 Location: Toronto	Picked up the transformer today! Potted 80 VA from Sumr in Toronto. Now to order the heatsinks and the rest of the parts. Then, either make a box -- or stuff it into rectangular aluminum tube, a la Peter Daniel. heatsinkusa looks like the best source.