Outstanding! that picture should also be placed in the gainclone projects thread. Yes I know that is not a gainclone, but it is a chip amp and a well done one I might add, and looks cool in the cardboard box.
Just remember to have some vents in the Oak chassis you and pop are building so the heat sinks can breath. Also I did not see a fuse on the mains.
I can't wait to see it finished..
Just remember to have some vents in the Oak chassis you and pop are building so the heat sinks can breath. Also I did not see a fuse on the mains.
I can't wait to see it finished..
Cheers Guys,
There are 2 amp fuses on each transformers primary (plus a 5a in the uk mains plug.
Totally right about the ventilation, these things really chuck out some heat. Totally different to my normal LM3886 gains clones it that regard.
I am gonna let them bed in for a couple of days with telly watchng duty before i listen critically. Sound pretty nice already though
There are 2 amp fuses on each transformers primary (plus a 5a in the uk mains plug.
Totally right about the ventilation, these things really chuck out some heat. Totally different to my normal LM3886 gains clones it that regard.
I am gonna let them bed in for a couple of days with telly watchng duty before i listen critically. Sound pretty nice already though
Hmm.
To be honest I think they are pretty decent size. There each have a 100mm * 50mm *50 mm heatsink. The part number is 5075251 from RS and they are rated at 1.7degC/W.
I chose them since they have a lot of radianting surface area in a quite short layout which is what i plan for the oak boxes. These will be built so that the heatsink sticks out of the side of the oak box, a athestic choice i fancy plus i mean far less heat inside the enclosure. Something i have always found in my IT work seem to degrade eletrolytics very quickly.
I think they might be heating up at the moment due to the fact they have little to no air flow underneath. I am going to attack to boxes to night to see if this lowers the temp.
If anyone else has any opions wether these heatsinks are too small that would be very much welcome prior to finalising the oak boxes.
Cheers guys,
Phil
To be honest I think they are pretty decent size. There each have a 100mm * 50mm *50 mm heatsink. The part number is 5075251 from RS and they are rated at 1.7degC/W.
I chose them since they have a lot of radianting surface area in a quite short layout which is what i plan for the oak boxes. These will be built so that the heatsink sticks out of the side of the oak box, a athestic choice i fancy plus i mean far less heat inside the enclosure. Something i have always found in my IT work seem to degrade eletrolytics very quickly.
I think they might be heating up at the moment due to the fact they have little to no air flow underneath. I am going to attack to boxes to night to see if this lowers the temp.
If anyone else has any opions wether these heatsinks are too small that would be very much welcome prior to finalising the oak boxes.
Cheers guys,
Phil
"If anyone else has any opions wether these heatsinks are too small that would be very much welcome prior to finalising the oak boxes.
Cheers guys,
Phil"
As long as you have GOOD airflow and don't plan on DJ'ing with the amp that should be good. Worst case is taller feet to allow more air from bottom to top or a slow fan.
Remember the LM3886 has overtemp protection. But I seriously doubt you would experience it. I have still yet to over heat any LM chip.
Cheers guys,
Phil"
As long as you have GOOD airflow and don't plan on DJ'ing with the amp that should be good. Worst case is taller feet to allow more air from bottom to top or a slow fan.
Remember the LM3886 has overtemp protection. But I seriously doubt you would experience it. I have still yet to over heat any LM chip.
I'm using much smaller sinks for months now....
Perforate the floor underneath the sinks and leave an escape route for rising hot air...
Perforate the floor underneath the sinks and leave an escape route for rising hot air...
thats what i have done on the proto type now. Runs a lot cooler though still quite warm compared tot a standard Lm3886 setup.
Sounds pretty nice, Bass is very nicely controlled.
Like i said 2 days to run it in playing tv and radio all day before i test against the regular gainclone.
Sounds pretty nice, Bass is very nicely controlled.
Like i said 2 days to run it in playing tv and radio all day before i test against the regular gainclone.
Hmm.
I am using a Ad815 based preamp cuiruit with a DC negating servo. Beacuase of that there is no Caps at all in the signal path until the Power amp so I guess it is wise to leave one there.
What is the standard Input caps like in terms of quailty, is it polypropylene? Also what value is it. I have some BIG 4.7uf LCR polypropylene caps which work very well as input caps on a T-amp. Are these any use in this appication or are the values way off.
Phil
I am using a Ad815 based preamp cuiruit with a DC negating servo. Beacuase of that there is no Caps at all in the signal path until the Power amp so I guess it is wise to leave one there.
What is the standard Input caps like in terms of quailty, is it polypropylene? Also what value is it. I have some BIG 4.7uf LCR polypropylene caps which work very well as input caps on a T-amp. Are these any use in this appication or are the values way off.
Phil
Well I tend to have other experiences with heatsinking.The amp can go very loud on most types of music without the need for bigger heatsinks than what you have.However you should test it with your favourite bass heavy music to really see how it fares in your set up.Something like Massive Attack or Kruder and Dorfmeister or even some recent Red Hot Chili Peppers at high levels will heat things up very quickly.Then the spike protection will kick in.Depends on room size,speakers,listening levels etc etc.
Ok,
I have a meter length of copper about 100 mm wide and 5mm thick, I might try using a section of this as additional heatsinking.
I have a meter length of copper about 100 mm wide and 5mm thick, I might try using a section of this as additional heatsinking.
The standard kit input cap is a Epcos 1uF 305V Polyprop.
Initially the amp was designed for a 1uF Polyester, but we changed the board to accomidate the larger MKP. Anything with a 22.5mm pin spacing (or smaller) will fit on board. For larger than that, I recommend using an axial cap off board.
As to whether you need an inout cap, just measure the DC on the incoming signal with your multimeter.
Initially the amp was designed for a 1uF Polyester, but we changed the board to accomidate the larger MKP. Anything with a 22.5mm pin spacing (or smaller) will fit on board. For larger than that, I recommend using an axial cap off board.
As to whether you need an inout cap, just measure the DC on the incoming signal with your multimeter.
I agree with the no cap is the best cap school after my recent heaphone amp building stint, however I won't be that wild with my valve buffered Rev C... I like dem glass tubes, I just don't trust anything that can kill me that easily yet looks harmless....
Brian you would cry if you saw what I did to accommodate my bigass ampohm caps...
Brian you would cry if you saw what I did to accommodate my bigass ampohm caps...
protos said:
I havn't found anything about that one in here! Is that a further refinement of the RevC, or is it a new design?
lpm76 said:
Some of both. It has some new features, such as a DC nulling servo, and it has the capacity for parallel current pumps(LM3886s).
The biggest difference is between it and the original REV A.
Mauro has not published the schematics though, so its hard to say what the exact differences are.
Ever since his bad experiences here dealing with some in the hobby (thankfully those people are not here any longer) he has been very reluctant to share details of new designs here. I don't blame him at all.
Bottom line, if Mauro designed it, I am quite sure it is good.
Cheers!
Russ
You can find more about it on his personal web page: http://translate.google.com/transla...fe=off&ie=UTF-8&oe=UTF-8&prev=/language_tools