Correct on both,my prefferance also... however I need to test this way to make sure the amp works when built by little monkeys...
The angle stock is way too thin, but I just don't have the money this month for more large expenses, and have to buy the propper stuff in 5m lenghts... ($50) next month, it will be high on the priority list.
The angle stock is way too thin, but I just don't have the money this month for more large expenses, and have to buy the propper stuff in 5m lenghts... ($50) next month, it will be high on the priority list.
Doh, good thing I posted a photo, I see an inverted cap... and that after so religiously assembling this unit... went through 1 sqaure meter of PCB prototypeing this amp.
Hey Nico,
Is the final board going to have room for a single-turn bias adjust? They are usually not available in the vertical form you are using in this prototype. That form is usually reserved for multi-turn trimmers. (Unless you have a source I haven't discovered yet).
..Todd
Is the final board going to have room for a single-turn bias adjust? They are usually not available in the vertical form you are using in this prototype. That form is usually reserved for multi-turn trimmers. (Unless you have a source I haven't discovered yet).
..Todd
send me a picture or a catalog no. to look at please...
I know Carlos likes single turn too as it is easier to recover from a very wrong setting, fast.
I'm in the habit of useing these multiturns, as they just outlast the singleturn pots when you desolder them often, also they are sealed, so less harmed by enviromental things like smoke and dust...
I know Carlos likes single turn too as it is easier to recover from a very wrong setting, fast.
I'm in the habit of useing these multiturns, as they just outlast the singleturn pots when you desolder them often, also they are sealed, so less harmed by enviromental things like smoke and dust...
Hi Nico,
Here are some suitable ones I think:
(It's usually easy to make the pad footprint fit either your multi-turn ones, or these ones, with just one extra pad -- assuming you have the room available.)
Copal CT-6 is 6mm square (1/4" ?) sealed, single turn, available (not sure how common worldwide), cheap-ish
http://info.tactnet.co.jp/copal/e/product/pdf/trimmer_potentiometers/ct6_en.pdf
and a link to equivalent Digikey USA's catalog page (for pricing reference):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CT6EP102-ND
Bourns 3362P is 1/4" square, sealed, single turn, commonly available, cheap-ish
http://www.bourns.com/PDFs/3362.pdf
and a link to equivalent Digikey USA's catalog page (for pricing reference):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=3362P-102LF-ND
Here are some suitable ones I think:
(It's usually easy to make the pad footprint fit either your multi-turn ones, or these ones, with just one extra pad -- assuming you have the room available.)
Copal CT-6 is 6mm square (1/4" ?) sealed, single turn, available (not sure how common worldwide), cheap-ish
http://info.tactnet.co.jp/copal/e/product/pdf/trimmer_potentiometers/ct6_en.pdf
and a link to equivalent Digikey USA's catalog page (for pricing reference):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CT6EP102-ND
Bourns 3362P is 1/4" square, sealed, single turn, commonly available, cheap-ish
http://www.bourns.com/PDFs/3362.pdf
and a link to equivalent Digikey USA's catalog page (for pricing reference):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=3362P-102LF-ND
Thanks guys, I'll try to work them in....
Listening to Precision I now. After ioncludeing your trimpot, I think we can stamp and coin it. 😀
Listening to Precision I now. After ioncludeing your trimpot, I think we can stamp and coin it. 😀
I am most surprised how well that thin angle stock is working...
Personly I had great reservations inside... but I have been pumping the amp loud enough to have had to go appologise to the neighbours- before- they complain...
Maybe a 3 degree diffirence between the angle and the heatsink...
The trebble is sounding a bit better on this build despite the fact that used a whole 100pf in Cdom (to make sure I am not fighting 3 battles at once), It is going to sparkle when I drop that value a little...
Had some innital problems when I underbiased the amp... nothing major, just a few ticks in the first minute.... Then noticed that theory and real world do not always match.... Readjusted bias using Vbe of an output transistor... and the problems dissapeared..
Personly I had great reservations inside... but I have been pumping the amp loud enough to have had to go appologise to the neighbours- before- they complain...
Maybe a 3 degree diffirence between the angle and the heatsink...
The trebble is sounding a bit better on this build despite the fact that used a whole 100pf in Cdom (to make sure I am not fighting 3 battles at once), It is going to sparkle when I drop that value a little...
Had some innital problems when I underbiased the amp... nothing major, just a few ticks in the first minute.... Then noticed that theory and real world do not always match.... Readjusted bias using Vbe of an output transistor... and the problems dissapeared..
Nordic said:
What kind of cap are you using? I have some nice ones you can try (mica, I think).
Hey Shaun (speaks softly so I can't be heard) useing a mixture of monolythic ceramics and NP0... (but do have nice 100pf caps (not mica though)...
All I have left in mica is 24pf and I think one 10pf.. ******* stuff is so expensive...
For this amp I need two caps which are still ceramic on mine that bugs me... one is 12pf and one is 470pf (do you get micas that big?) oh and the Cdom I need a mica in is 68pf....
If you got any of those 3 I'd be interested. they are all 3 pretty dead solid in the signal path...
All I have left in mica is 24pf and I think one 10pf.. ******* stuff is so expensive...
For this amp I need two caps which are still ceramic on mine that bugs me... one is 12pf and one is 470pf (do you get micas that big?) oh and the Cdom I need a mica in is 68pf....
If you got any of those 3 I'd be interested. they are all 3 pretty dead solid in the signal path...
Do you remember Nico?... capacitors in series reduce the value.
So you can try two 100pf to obtain 50pf to your testings...and to different values have only to calculate.
"L" shape, having nice contact area with the main heatsink works fine....... thickness only create delays into the heat transference and use to fool us...we have to wait to see the real thing working.
3 Milimeters aluminium is fine....heat transference depends area in contact with air to allow cooling..... thickness is not important, only increase mechanical qualities and weigth...also price.
There's a deep valley between theories and reality... and how deep it is depends on you having experiences into daily bases.
150 watts transistors, for instance, if you put it to dissipate 100 watts it will burn!.... not really able to dissipate that stuff..... they conclude that dissipation informed into data sheet using a big machine connected to the transistor.... an enormous huge heatsing artificially (non natural) equiped with machines to keep the metal block (the heatsink) into 25 degrées celsius..... and we have not that sittuation in real life...so.... you need to be skilled not to be fooled....skilled into the day by day real work holding soldering iron and facing those problems...also a 15 amps transistor cannot hold 15 amps...ahahahahha..sometimes less, sometimes more.
Into theories we came from Apes.....but we have more things alike us into genetic with Rats...Mouses.
We know so small things about a lot of sciences that genetics, for instance, says we are very alike thousands animals..of course we know nothing about the subject...do not make sense almost same genetics and so different animals..... so must take care about theories..they are, some of them, in development.
World was considered squared....some years ago..almost yesterday...
regards,
Carlos
So you can try two 100pf to obtain 50pf to your testings...and to different values have only to calculate.
"L" shape, having nice contact area with the main heatsink works fine....... thickness only create delays into the heat transference and use to fool us...we have to wait to see the real thing working.
3 Milimeters aluminium is fine....heat transference depends area in contact with air to allow cooling..... thickness is not important, only increase mechanical qualities and weigth...also price.
There's a deep valley between theories and reality... and how deep it is depends on you having experiences into daily bases.
150 watts transistors, for instance, if you put it to dissipate 100 watts it will burn!.... not really able to dissipate that stuff..... they conclude that dissipation informed into data sheet using a big machine connected to the transistor.... an enormous huge heatsing artificially (non natural) equiped with machines to keep the metal block (the heatsink) into 25 degrées celsius..... and we have not that sittuation in real life...so.... you need to be skilled not to be fooled....skilled into the day by day real work holding soldering iron and facing those problems...also a 15 amps transistor cannot hold 15 amps...ahahahahha..sometimes less, sometimes more.
Into theories we came from Apes.....but we have more things alike us into genetic with Rats...Mouses.
We know so small things about a lot of sciences that genetics, for instance, says we are very alike thousands animals..of course we know nothing about the subject...do not make sense almost same genetics and so different animals..... so must take care about theories..they are, some of them, in development.
World was considered squared....some years ago..almost yesterday...
regards,
Carlos
Recommended voltage of capacitors
Dear Carlos and Nico,
Could you give some guidance on the required minimum voltage ratings of the capacitors.
Only C16 is specified at 160V because it could see 2*63VDC across it if the output transistors fail.
I wondered about C23-25 & C26.
Regards,
Francois
Dear Carlos and Nico,
Could you give some guidance on the required minimum voltage ratings of the capacitors.
Only C16 is specified at 160V because it could see 2*63VDC across it if the output transistors fail.
I wondered about C23-25 & C26.
Regards,
Francois
Francois in reality, a lower voltage cap there will be fine for most amps for most of their lifetimes... The resistor tends to take most of the beating under fault condition... however the failure of that cap is not undocumented, and if it does go, fixing everything else won't be a complete repair...
For the 55V sections of the amp, a 63V cap will be fine...
Carlos and I dissagree on the voltage rateing of the other caps...
In some ways I am more paranoid than him and opted for 100V caps (especialy as I have 70V rails). His experience which exceeds my lifetime suggests that useig a cap at the rated voltage is fine...
I am just not sure if that will be enough for my insurance guys if I burn down the house...
For the 55V sections of the amp, a 63V cap will be fine...
Carlos and I dissagree on the voltage rateing of the other caps...
In some ways I am more paranoid than him and opted for 100V caps (especialy as I have 70V rails). His experience which exceeds my lifetime suggests that useig a cap at the rated voltage is fine...
I am just not sure if that will be enough for my insurance guys if I burn down the house...
Nordic said:
Why don't you try polystyrenes for the larger values? IMHO they sound much better than mica, they did in the past in every RIAA circuit I assembled.
You may not find all values, but some you will. If not Wima polyprops should be my next choice.
For the smaller values COG ceramics might be available, even if they would not be my first choice.
Maybe I'm old fashioned, but I tend to look at capacitors in small signal filter tasks as if they were all RIAA circuits.
Yes I am useing 100pf polystyrene made by Diel, when i was jsut a lad, maybe some 20 years ago, I used to order these bags of random components from the electronics magazines in the UK... got a bunch of these caps, never realy had a use for them until the last year or so...
As new items these caps cost the same as mica over here... +-$3 each and only sold in 5s.
I had to build the amp with some crappy components to make sure it sounds well out there in the real world where I can not cotrol component choice. My personal units are all upgraded loveingly over time.
As new items these caps cost the same as mica over here... +-$3 each and only sold in 5s.
I had to build the amp with some crappy components to make sure it sounds well out there in the real world where I can not cotrol component choice. My personal units are all upgraded loveingly over time.
Nordic wrote (in ...Dx amp...my amplifier - thread):
Nordic, could you post a photo of the circuit side of the PCB, so we can see how the components on that side are to be mounted.
It appears that you have soldered the component leads along the copper trace, as I cannot see any sign of them on the component side - eg. holes with leads protuding.
Will the final PCB have provision for holes through a copper trace on the corcuit side, to allow secure mounting?
I couldn't find metal film 4.7 ohm resostors so ended up ordering expensive Caddock MK132, which apparently have to go on the circuit side.
I have not checked all the components, but noticed the six 4.7 ohm 1/4W and two 0.33 ohm 2W resistors missing from the component side.
billabong.
Nordic, could you post a photo of the circuit side of the PCB, so we can see how the components on that side are to be mounted.
It appears that you have soldered the component leads along the copper trace, as I cannot see any sign of them on the component side - eg. holes with leads protuding.
Will the final PCB have provision for holes through a copper trace on the corcuit side, to allow secure mounting?
I couldn't find metal film 4.7 ohm resostors so ended up ordering expensive Caddock MK132, which apparently have to go on the circuit side.
I have not checked all the components, but noticed the six 4.7 ohm 1/4W and two 0.33 ohm 2W resistors missing from the component side.
billabong.
Hi Billabong, Carlos asked me not to post pictures of that side of the board.. the only components that NEED to go under the boards are 2 of the power resistors... and bypass caps where and if you want to use those.... all with through hole pads... I used a nail clipper that is why you are not seeing protruding wires...
Also most of the wire links can go under the board too for neatness... I was realy torn up as to useing them or not, but in the end decided that a star ground was pretty high on my priorities..
the 4R7 can go on top, no problems...
give a shout if anything else worries you, my wife and I am listening to the precision 1 right now.. 😀
Also most of the wire links can go under the board too for neatness... I was realy torn up as to useing them or not, but in the end decided that a star ground was pretty high on my priorities..
the 4R7 can go on top, no problems...
give a shout if anything else worries you, my wife and I am listening to the precision 1 right now.. 😀
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