What I can see is how to hook up the 5k pot to it. It has already two trimmers there, of 200ohm. The 5k isn't shown in my schematic, I can't see it, sorry
I would thank any help about that matter.Sabre, those heatsinks are definitly too small. Also your speaker output wires seem too thin, hook up there something of higher gauge. I would also place the obligattos between the connectors and the heatsinks.
I have made a plan for testing the tantalum resistors and the LM318 in both packages. First, I will populate both boards with the PRP resistors, but one with the metal can encapsulation and one with a DIP-8 ic. I will let it burn-in for some days, like 100 or 150 hours, to not address false results due to not burned-in components. After a detailed extensive listening session (to be able to memorize it's sounding characteristics), I will try to find any difference between both boards. Listening one board at a time, of course. Though, I am not expecting any discernable audibly difference between both IC's.
Then, I will put the same IC in both boards, and listen to it again. After having memorized it sound, I will quickly change the PRP resistors for the tantalum ones, and I will listen for further changes. I will expose all the differences my humble ears are able to discern.
My heatsinks are really killer ones at 30x12x5cm (12x5x2 inches) size, one of them for each board.
I don't have data for your build nor your ambient conditions, but if I were allowed to guess then 300 by 59 by 50mm (sawn to half height) would probably do for a pair of 3886, not just one.
I bet one heatsink should be able to handle even 4 LM3886. I wasn't intended to buy this one so big, but the enclosure I liked had that big heatsinks. Is this one:
modushop.biz
And I am going to put inside a Myref_C and an standar gainclone I have without enclosure, from chipamp.com.
modushop.biz
And I am going to put inside a Myref_C and an standar gainclone I have without enclosure, from chipamp.com.
A heat spreader can be as simple as a piece of 1.5 -2 inch wide piece of aluminum from a hardware store. When I make "cheap" chipamps for people I cut a 6 to 8 inch long piece of Aluminum strap from Home Depot. Different store but:
Shop Steelworks Aluminum Flat 1/16" x 1-1/2" x 6' at Lowes.com'
Just cut a length of that and mount it between the chips and the chassis with thermal paste. This bar will spread the heat to a larger area of the thin chassis and the chassis will dissipate the heat. The chassis wall is too thin to spread the heat quickly enough but a 1.5 wide x 8 long x 1/8 inch thick piece of metal will spread the heat to a larger area on the chassis. Remember the thermal paste and insulation!!
As for the 318, if the amps work with a good 318, then it has to be a pin compatibility issue or a voltage supply issue. Easiest first step is to measure the voltages to the 318.
Hi guys,
I have a few more dumb questions as I continue to stuff my boards.
- Does the 220 uF Blackgate go to C9, it's unclear from the boom ?
- I recieved 4 tiny little ceramic caps with my kits and I'm having trouble figuring out where two of them go. One came attached to a peice of cardboard and is labeled uc221, the other is loose with shorter legs and is labeled 100 on one side and K2J on the other.
- As added info could anyone tell me where the other two go, I installed them in C12 and C21, but would like to make sure before I'm done and fire them up.
- I'm assuming that you just leave the spots for the caps that aren't being used blank without jumpers (C17-20), am i correct ?
Many thanks,
PJN
I have a few more dumb questions as I continue to stuff my boards.
- Does the 220 uF Blackgate go to C9, it's unclear from the boom ?
- I recieved 4 tiny little ceramic caps with my kits and I'm having trouble figuring out where two of them go. One came attached to a peice of cardboard and is labeled uc221, the other is loose with shorter legs and is labeled 100 on one side and K2J on the other.
- As added info could anyone tell me where the other two go, I installed them in C12 and C21, but would like to make sure before I'm done and fire them up.
- I'm assuming that you just leave the spots for the caps that aren't being used blank without jumpers (C17-20), am i correct ?
Many thanks,
PJN
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
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.
Every LM318 I ordered was a Nat Semi. I had to order from no less than 4 different sources to get them all for some reason. Anyway, all Nat Semi. My LM318 look like your LEFT IC with only an etching in the surface and no silkscreen on the top like your RIGHT IC.
So from what you have said we can probably rule out a dead LM318 but we can rule IN that the proper LM318 will do the trick. I honestly wonder if the silkscreened one is a real Nat Semi chip. I know I sent it to you but obviously I am not in the fake IC business and obviously you have two supposedly Nat Semi ICs of which only one works.
Your other 5 that DONT work: Where did you get them from and do they look like the silkscreened one?
From what I remember from the previous buy and from earlier posts in the original thread a lot of people have had clicking trouble. I wonder if your home voltage is lower than normal and if for some reason its fine for the one IC and right there on the line of fine/not fine for the other ICs.
Troy I think you have helped a few people with this. Wasnt there a resistor that folks lowered the value of when they had the clicking trouble?
The sink is just way to small and the sinks on your Caddocks are going to let your Caddocks fry. This is basically a non starter. If you leave in those heatsinks they will fry if they have not already. Both the LM3886 and the Caddock but the Caddock first.
I also wonder where is the 470k resistor near the opamp on the left side. Maybe you mounted it below.
Forget my 470k remark. I saw your answer.
REGI, with the LDRs facing away from you the trimmer on the LEFT should be a 5k. Use the 5k pot here. 200r will still allow the board to work but you wont have balance control. 200R only belongs on the right hand side and it will allow balance control there for balancing minimum resistance of the shunt LDRs but will not effect the max resistance. The 5k has a large effect on the max resistance of the series so therefore you can have balance control.
Uriah
REGI, with the LDRs facing away from you the trimmer on the LEFT should be a 5k. Use the 5k pot here. 200r will still allow the board to work but you wont have balance control. 200R only belongs on the right hand side and it will allow balance control there for balancing minimum resistance of the shunt LDRs but will not effect the max resistance. The 5k has a large effect on the max resistance of the series so therefore you can have balance control.
Uriah
That will give you, not just a balance control, but a "panorama" control. I don't know the english word for that, but maybe you get the point. Nice explanation, now I get it. But I have to think if it is better to not implement it and assure a measured mathematically exact channel balance with the trimmers.
Could K2 be, like uriah proposes, some code for identifying it as a Kemet device?
If you go for balance control using your DMM and not your ears you may be disappointed. Balance control is to help with the asymmetry of your system components and your room. I dont really care in my system if my left LDR is 1k more than my right LDR as long as that is the setting that properly centers the stereo image.
That last statement goes for the series LDRs. I prefer the Shunt to be balanced at min setting with the trimmer and DMM. After that I use my ear with the 5k.
Uriah
min setting = maximum attenuation = maximum shunt LDR resistance = maximum LED current = minimum in series LED resistance.
Can you confirm?
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