Crispycircuit - I picked the heatsinks up at a local scrap metal yard - I was originally looking for some angle aluminium but saw these and thought they 'looked' about right - and only £10 for about 2m, so enough for at least one more amp 
Am sure you should be able to source similar profile ally in the US from stockists - I checked and similar sections are available in the UK only issue being they sell in 3m lengths!
Kei - thanks for the feedback. I need to sort out the noise problem 1st, (and also my scope) before I can tell whether the epcos coils are balancing the bridge. Certainly the amplifier sounds ok, and to my ears better than my AV amp (an RXV771), but the noise is worrying. Am not sure whether it is because I have been listening to class D for so many years that I expect total silence at 0 volume, maybe it's the carbon resistors around the input stage..
Also the hum from the trafo is annoyingly loud, I did look to see whether an SMPS would work, but the only affordable ones are from vendors in China on eBay so (in my view) somewhat risky. Hopefully it can be sorted with a cct to remove any DC offset on the input.
Will report progress as and when I make any!
Cheers
Am sure you should be able to source similar profile ally in the US from stockists - I checked and similar sections are available in the UK only issue being they sell in 3m lengths!
Kei - thanks for the feedback. I need to sort out the noise problem 1st, (and also my scope) before I can tell whether the epcos coils are balancing the bridge. Certainly the amplifier sounds ok, and to my ears better than my AV amp (an RXV771), but the noise is worrying. Am not sure whether it is because I have been listening to class D for so many years that I expect total silence at 0 volume, maybe it's the carbon resistors around the input stage..
Also the hum from the trafo is annoyingly loud, I did look to see whether an SMPS would work, but the only affordable ones are from vendors in China on eBay so (in my view) somewhat risky. Hopefully it can be sorted with a cct to remove any DC offset on the input.
Will report progress as and when I make any!
Cheers
With the noise issues, do you think the missing ground plane from the upper side of the pcb has anything to do with it. Did you incorporate the quad 606 mods for reducing noise pickup?
Kei,
I think most of those mods relate to impulse noise protection although for sure the ground plane on the component side may have greater impact on the 'white' noise I am able to detect.
I am going to replace these carbon resistors with metal film first -
R1, R2, R6, R5, R11, R25 and make R11 12Ohm so gain is reduced to .755V =1mW into 600Ohm which should improve the s/n ratio too.
Also will fit 100nf decoupling capacitors across D1,2,12
I live in an electrically noisy house - very old central heating system lots of It kit, rubber insulated electrics etc, so impulse/mains borne noise is likely quite high so I fitted an integrated filter IEC socket which seems to get rid of any clicks and plops -one of these
BZM27/A0620/57B - BULGIN - FILTER, INLET, IEC, 6A, DPST | Farnell United Kingdom
Will keep you posted as to results
Cheers
I think most of those mods relate to impulse noise protection although for sure the ground plane on the component side may have greater impact on the 'white' noise I am able to detect.
I am going to replace these carbon resistors with metal film first -
R1, R2, R6, R5, R11, R25 and make R11 12Ohm so gain is reduced to .755V =1mW into 600Ohm which should improve the s/n ratio too.
Also will fit 100nf decoupling capacitors across D1,2,12
I live in an electrically noisy house - very old central heating system lots of It kit, rubber insulated electrics
etc, so impulse/mains borne noise is likely quite high so I fitted an integrated filter IEC socket which seems to get rid of any clicks and plops -one of theseBZM27/A0620/57B - BULGIN - FILTER, INLET, IEC, 6A, DPST | Farnell United Kingdom
Will keep you posted as to results
Cheers
excuse me for being a killjoy but the pcb designed for this amplifier is actually horrible and i presume that there is going to be obvious oscillations if not other pcb related problems
it is very bad practice to run such big parallel lines especially if these are the base the emitter and the collector of a transistor.... instead you take the driver closer and then ..... cooling NPN transistors in Texas and PNP ( or the other side ) in New York is number one reason fro thermal run away .... you will never achieve thermal balance in this amplifier
It is very bad practice to stretch the pcb to meet the size of the box ... you stretch the heatsink better ..
This is just my opinion and obviously these has no effect if you expect your amp to play cause it will ...point is how well it can play taken also in mind that you already spent a small fortune on parts that are seriously compromised by the pcb .
kind regards
sakis
it is very bad practice to run such big parallel lines especially if these are the base the emitter and the collector of a transistor.... instead you take the driver closer and then ..... cooling NPN transistors in Texas and PNP ( or the other side ) in New York is number one reason fro thermal run away .... you will never achieve thermal balance in this amplifier
It is very bad practice to stretch the pcb to meet the size of the box ... you stretch the heatsink better ..
This is just my opinion and obviously these has no effect if you expect your amp to play cause it will ...point is how well it can play taken also in mind that you already spent a small fortune on parts that are seriously compromised by the pcb .
kind regards
sakis
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Sakis,
Happy to accept critcism, however this is a class C amp driven by a class A stage, and for sure each half of that A stage is at either end of the PCB, just like the original, just slightly longer, so unsure what thermal runaway I am likely to encounter.
Also not sure I understand the 'small fortune on parts', as I have previously stated this was merely a proof of concept during which I made plenty of mistakes and from which I can learn.
Cheers
Happy to accept critcism, however this is a class C amp driven by a class A stage, and for sure each half of that A stage is at either end of the PCB, just like the original, just slightly longer, so unsure what thermal runaway I am likely to encounter.
Also not sure I understand the 'small fortune on parts', as I have previously stated this was merely a proof of concept during which I made plenty of mistakes and from which I can learn.
Cheers
The sole advantage of a toroidal transformer is the possibility of a low profile which is generally not the case in a power amplifier because other factors (heatsink size for one) makes the case big.
In an attempt to make the toroid small, many manufacturers push the flux density towards and sometimes beyond the limits. They also use a rectangular core section to reduce the overall height which makes the transformer less efficient. The net result is a high level of mechanical vibration especially if the windings are not properly tensioned and/or the tension is not even. This vibration can cause a very loud audible 'hum' which is often confused for electrical noise. Of course, dc on the primary winding can exacerbate this problem without being the primary cause.
Potting the toroid in a steel box is an effective solution.
I meant to comment on the 'EMC' mods earlier. The original problem is that the speaker ground/return wire is not terminated according to best EMC practice. This leads to noise pickup and injection into the amplifier front end.
The Quad mod had to be fitted to exisiting amplfiers so it is an improvement on an unmodified amplfier but is still far from best practice.
If you are building from scratch (which is the advantage of DIY) then you can implement a proper grounding scheme. There is a good articel on this site for your guidance.
About trafo noise this might help.
http://www.diyaudio.com/forums/powe...t-buzzing-toroid-transformers-what-right.html
And I noticed really high mains voltage in London where I live. It is almost 250V so 230V primary transformer might approaching to saturation......
Cheers
http://www.diyaudio.com/forums/powe...t-buzzing-toroid-transformers-what-right.html
And I noticed really high mains voltage in London where I live. It is almost 250V so 230V primary transformer might approaching to saturation......
Cheers
That is so high that I think you could be asking your supplier to come and check to confirm.
If they are regularly approaching maximum voltage then you can demand that they change the tapping on the local distribution transformer.
If that puts others on to too low a voltage then that is the supplier's problem, not yours.
BTW,
a universal transformer designed for 230Vac should be designed to operate safely and correctly over the full range of the harmonised european supply voltage, i.e. 216Vac to 254Vac.
Andrew, I see 244V at my house -a bit out in the sticks and fed by overhead cables, so one might assume that they might up the voltage at the substation since the runs are long.
This already caused me to put 6 diodes in series on the secondary since the +ve rail was too close for comfort to the 63V rating of the smoothing caps (reduced it to ~61V)
Cheers
This already caused me to put 6 diodes in series on the secondary since the +ve rail was too close for comfort to the 63V rating of the smoothing caps (reduced it to ~61V)
Cheers
Andrew, it is really so high. I live in Camden , London. I noticed it because my computer monitor shuts down. My first thought was that it's been damaged during transport from my home country. I opened it and check everything. I even replaced smoothing elco at psu....
Because it's almost new Samsung I wasn't willing to replace it so I checked datasheet for switching chip. It is TOP...something and I noticed that it has built in overvoltage protection....so I connect it via 2 wirewound resistors......and it works perfectly since than.
But of course voltage isn't so high all the time. When dinner is cooking...you know the rest.
Cheers
Because it's almost new Samsung I wasn't willing to replace it so I checked datasheet for switching chip. It is TOP...something and I noticed that it has built in overvoltage protection....so I connect it via 2 wirewound resistors......and it works perfectly since than.
But of course voltage isn't so high all the time. When dinner is cooking...you know the rest.
Cheers
I note there are now three suppliers offering clone 606 boards that appear to include the ground plane on the component side, e.g. this one:
one set Quad 606 Power Amplifier bare Boards for DIY or Repair Amp x2 | eBay
I have taken the plunge and ordered a pair recently, so will report when I get the boards as to whether this is a true ground plane or just surface printing of some sort
Also going the hand made inductor route at present for the 1u5H.....
one set Quad 606 Power Amplifier bare Boards for DIY or Repair Amp x2 | eBay
I have taken the plunge and ordered a pair recently, so will report when I get the boards as to whether this is a true ground plane or just surface printing of some sort
Also going the hand made inductor route at present for the 1u5H.....