MyRefC build guide

[regiregi22]

It came with the kit two types of isolators for the heatsink: One grey band, and two transparent ones. For what purpose? using the one I prefer?

Is the LM318H with the metal can encapsulation isolated? I mean, is any pin tied to the encapsulation? I have measure that NOT, but I would like to be sure.

In the LDR and boards bag, apart from the components, it comes with a dual 100k linear pot. Which, BTW, gives a very pleasant sensation when rotating it, very smooth. It is an ALPS too. What I don't know what it is for is a single gang 5k pot from an unknown vendor. I suppose that is for balancing or something like that. Is there any mounting manual or instructions available? I am afraid of skrewing it up I would be very pleased.

In the next episode, how to decypher the attached paper with numbers and measurements from the LDR's

All in all, a very very very nice packed kit, I wasn't expecting a so PRO grade kit.ñ

Regards,
Regi

[udailey]

Thanks Regi,
Grey band and transparent: Both for same - you pick. I had the transparent mica ones for this buy and then Steve at APEXJR threw in the grey band which will do the trick as wel.
LM318H you might try the datasheet. I dont know but I imagine you worry about it touching the Caddock heatsink. I might put some grey band on the top of it to be sure.
The 100k remember is excess that I had on hand and is linear. This was thrown in for free as I had hundreds and no use for it. It will get you running but wont give very smooth volume control. It will change volume rather abruptly. You will want to change to a dual log when you get a chance. 5k is for balance. Goes to 'Series Balance' on the little board. Regi, the schematic you drew represents my board perfectly so you already know how to use it.
Dont be afraid as long as you put the components in the right spot as per your schematic.
A few things to consider when using the LDR board.
1: dial that 200R pot to midpoint and THEN fire up the board. This way you have the protection of half of the pot plus a 68R resistor for each shunt LDR. You can not damage the series LDRs.
2: the paper with the numbers: its basically a measurement sheet of your LDRs. If you have a low 'max db difference' on the lowest measurement then use those for shunt LDRs. If you have a high 'max db difference' on the lowest measurement then use those for series. What is High or Low? Its only relative to the 'max db difference' at the other end of the measurements sheet. Pick the best numbers for shunt. All the numbers are "GOOD" numbers. I wont send out anything that isnt a very good match.

[Bill_P]

Originally Posted by regiregi22

Is the LM318H with the metal can encapsulation isolated? I mean, is any pin tied to the encapsulation? I have measure that NOT, but I would like to be sure.

The metal case of the LM318H is connected to pin 4, the V- supply. Be sure it does not touch anything else in the circuit.

[sabre66]

Ok lets get back to this lm318 I seem to be having. The last picture shows the two lm318. Board on the left is with the ic that works the one on the right is the new one which matches the one that came with the package. The board on the right will just click on and off. If I swap the two ic's around the one on the left will now start to click on and off. Each board will power up one at a time if I only use the ic from the left hand board in picture 3.
Which is telling me that the new lm318 I got is also bad? So I bought 5 and all the new ones are bad? I doubt it, but have been wrong before Now it is hard to read the package on the left hand board but they are distinctively different in there markings. Are thes two different manufactures in here. Please Uriah send me one that looks like the left hand one

Also every one seems to think the sinks maybe too small if thats the case I'll get different ones But for now I may just put some fans on them.

[troystg]

sabre66-

Please take as advice only and not criticism.

1. put the Obigatos on the other side of the PCB's. (Heat sink side)
2. rotate the two PCB's 90 degrees counter-clockwise and mount the LM3886's (insulated!) on the side wall with an aluminum heat spreader between the wall and the chips. That will be sufficient for cooling.


As for the 318 issue, are you able to hear music from each board when the "good" 318 is installed in them? Not just relay clicks but undistorted music? (provided that is what is playing and not an audio book or something)

[sabre66]

Originally Posted by troystg

sabre66-

Please take as advice only and not criticism.

1. put the Obigatos on the other side of the PCB's. (Heat sink side)
2. rotate the two PCB's 90 degrees counter-clockwise and mount the LM3886's (insulated!) on the side wall with an aluminum heat spreader between the wall and the chips. That will be sufficient for cooling.


As for the 318 issue, are you able to hear music from each board when the "good" 318 is installed in them? Not just relay clicks but undistorted music? (provided that is what is playing and not an audio book or something)

Thanks for your reply will get done right away, but I dont understand the heat spreader thing. Some photos I've seen are what look like aluminum U bar if thats all It is thats simple enough. Or I'll mount the chips to copper like in Peter Daniels Patek

Yes I am able to hear music when the "good" 318 is installed in each of the boards.

[40 watt]

Hi Uriah. My 4 boards came on Monday, very well packaged and arrived immaculate. Thank You!

[jcon2]

I can't see R39- 470K in the left board but is there on the right. Correct? Don't know if that explains the issue though.
Jack C

[sabre66]

Originally Posted by jcon2

I can't see R39- 470K in the left board but is there on the right. Correct? Don't know if that explains the issue though.
Jack C

R39 is on the bottom I had to pull it off it was easier to solder back on the under-side. The issue follows the lm318.

[westers151]

As for heatsinks, I asked this same question last year and Andrew gave me the same advice as he's given here.

I built a CarlosFM LM3886 amp running 35V rails and feeding an 8 ohm load, but being the over engineering type that I am I got heatsinks with a rating of 0.9C/W for each chip.

Do they get warm? Put it this way, I've spent ages with my hand on the sinks trying to work out if it's the chip that's making them warm or just the fact that the ambient temperature is hot and they're absorbing that heat.

Some might say that's overkill, but I call it insurance as I had no prior experience with how hot chip amps run.

Size wise they're about 8 inches wide and 4 inches tall, and the fins come out about 1.5 inches, and not that expensive from Farnell (uk). They're made by Fischer.

For this build I'll be going for 1.2C/w sinks, purely on the grounds of size, but given my experience with how warm (or the lack of) that the 0.9's have got for my kind of listening, then I'm happy that 1.2C/w's will work.