AudioSector-chip amp kits, dacs, chassis - Page 152

Peter Daniel · 5th January 2007, 08:13 PM

It is 901. Do you have any experience with VTA and tracking force?

I still have Maplenoll Ariadne to modify and expect it to be even better than Oracle; as to Oracle, I never liked the original design and I simply had to do some changes

Peter Daniel · 5th January 2007, 08:15 PM

The base uses the original acrylic plate, 3/4 aluminum and two 0.25 brass plates. The original control box was also nicely integrated.

Rob Thomas · 6th January 2007, 12:53 AM

Quote:

Originally posted by Peter Daniel
It is 901. Do you have any experience with VTA and tracking force?

I find I'm around 1.95g on tracking force. VTA, (actually SRA), varies per disc, but I find starting with the base of the cart parallel to the record is close, then it's by ear.

-RT

DaveM · 12th January 2007, 03:07 AM

I have a question about heat sinking. I am building up 3875 kit. Actually it has been up and running for about a year and is now facing being enclosed. I found amongst my pile of scraps and parts a piece of 6" OD 1" wall pipe. The steel is really low grade, (sparks and flaming chips when it is cut) but it does clean up nice. So, I was wondering if I will have sufficient heat sinking if I mount the chips to a piece of .375" plate that is press fit into a 6" OD 1" wall 5" tall piece of pipe. Initially I was only going to house the power supply in the pipe, but I have realized that I have room for all of it. I will probably shield the transformer with some copper foil I have kicking around. Here is a pic of the parts and pipe.

Thanks

DaveM

DaveM · 12th January 2007, 06:13 PM

Pic did not post. Try, try again.

Peter Daniel · 12th January 2007, 06:59 PM

It will probably work, but thermal release efficiency will be compromised by steel as a material, and also by substantial mass of the whole thing. Depending on how much you will be pushing the amps (volume and load), it may get only slightly warm, or may reach 40-50 deg and stay there. I was using brass rod to mount the chip (2" dia , 8" long and it was acting as heat tank, storing thermal energy, but not releasing)

Since you have it already made, it's worth trying anyway.

DaveM · 12th January 2007, 07:28 PM

I have some brass bar stock sitting around as well. I think I will add a piece of brass to the top cover and mount the chips to the brass. At least this way the heat transfer to the brass is pretty good and the thermal contact area to the steel will be vastly larger than the chip surface. It can't do anything but help.

Thanks for the insight.

DaveM

Peter Daniel · 12th January 2007, 11:02 PM

You can find the numbers here: http://hyperphysics.phy-astr.gsu.edu...les/thrcn.html

Copper would be best.

Mick_F · 14th January 2007, 01:48 PM

It also critically depends on your supply voltage. A supply below +-30V will heat up the chips significantly less than e.g. 35 or 40V.

Mick

DaveM · 14th January 2007, 04:48 PM

Looking a bit closer at that chart, I will be better off using aluminum with a good bit of thermal paste between the steel and aluminum to prevent issues with the dissimilar metals. I always thought that brass was a better conductor than aluminum. That was defiantly a misconception.

Thanks

Dave

12th January 2007, 06:59 PM	#1516
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	It will probably work, but thermal release efficiency will be compromised by steel as a material, and also by substantial mass of the whole thing. Depending on how much you will be pushing the amps (volume and load), it may get only slightly warm, or may reach 40-50 deg and stay there. I was using brass rod to mount the chip (2" dia , 8" long and it was acting as heat tank, storing thermal energy, but not releasing) Since you have it already made, it's worth trying anyway. __________________ www.audiosector.com

12th January 2007, 11:02 PM	#1518
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	You can find the numbers here: http://hyperphysics.phy-astr.gsu.edu...les/thrcn.html Copper would be best. __________________ www.audiosector.com

14th January 2007, 01:48 PM	#1519
Mick_F diyAudio Member Join Date: Jun 2005 Location: Cologne	It also critically depends on your supply voltage. A supply below +-30V will heat up the chips significantly less than e.g. 35 or 40V. Mick __________________ No statement here.

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12th January 2007, 03:07 AM	#1514
DaveM diyAudio Member Join Date: Feb 2003 Location: Vermont	I have a question about heat sinking. I am building up 3875 kit. Actually it has been up and running for about a year and is now facing being enclosed. I found amongst my pile of scraps and parts a piece of 6" OD 1" wall pipe. The steel is really low grade, (sparks and flaming chips when it is cut) but it does clean up nice. So, I was wondering if I will have sufficient heat sinking if I mount the chips to a piece of .375" plate that is press fit into a 6" OD 1" wall 5" tall piece of pipe. Initially I was only going to house the power supply in the pipe, but I have realized that I have room for all of it. I will probably shield the transformer with some copper foil I have kicking around. Here is a pic of the parts and pipe. Thanks DaveM

12th January 2007, 07:28 PM	#1517
DaveM diyAudio Member Join Date: Feb 2003 Location: Vermont	I have some brass bar stock sitting around as well. I think I will add a piece of brass to the top cover and mount the chips to the brass. At least this way the heat transfer to the brass is pretty good and the thermal contact area to the steel will be vastly larger than the chip surface. It can't do anything but help. Thanks for the insight. DaveM

14th January 2007, 04:48 PM	#1520
DaveM diyAudio Member Join Date: Feb 2003 Location: Vermont	Looking a bit closer at that chart, I will be better off using aluminum with a good bit of thermal paste between the steel and aluminum to prevent issues with the dissimilar metals. I always thought that brass was a better conductor than aluminum. That was defiantly a misconception. Thanks Dave