I hope so Sparkle, as we have not those fake specifications.
Depending the voltage you decide to use some range of power will result...we do not know exactly how many watts of heat some fake transistor will hold.
hehe....i think we have to make a burn test....when burned we will conclude the fake unit limit of power..ahahahha...not way to do that...so..we never know exactly if it will hold 50 watts of heat...80 watts of heat or even 150 watts of heat.
Also the maximum current....we just do not know...the better is to use your MJs...as they are something that we can trust.
I feel good...very happy, as you made the Dx amplifier choice.
I hope i can help you in something.
Inform the supply voltage and output impedance and i will suggest a lot of things...of course, if you need some.
regards,
Carlos
Depending the voltage you decide to use some range of power will result...we do not know exactly how many watts of heat some fake transistor will hold.
hehe....i think we have to make a burn test....when burned we will conclude the fake unit limit of power..ahahahha...not way to do that...so..we never know exactly if it will hold 50 watts of heat...80 watts of heat or even 150 watts of heat.
Also the maximum current....we just do not know...the better is to use your MJs...as they are something that we can trust.
I feel good...very happy, as you made the Dx amplifier choice.
I hope i can help you in something.
Inform the supply voltage and output impedance and i will suggest a lot of things...of course, if you need some.
regards,
Carlos
It is very strange, as Klaas enclosure may hold 430 watts.
I was using my "eye calculator"...and i have concluded that Klaas heatsink is more than enougth...as 2 channels will dissipate 320 watts of heat when driving 4 ohms loads and near the clipping.
Klaas heatsinks...even reducing heat sink capacity because some panels are not in the correct convection position..also the heatsinks are not in the best position...even this way, the case may be able to hold 2 channels of the Dx amplifier.
I am extremelly curious about.
Klaas is hardly busy...having small time those days...we will have his informs, i hope soon.
regards,
Carlos
I was using my "eye calculator"...and i have concluded that Klaas heatsink is more than enougth...as 2 channels will dissipate 320 watts of heat when driving 4 ohms loads and near the clipping.
Klaas heatsinks...even reducing heat sink capacity because some panels are not in the correct convection position..also the heatsinks are not in the best position...even this way, the case may be able to hold 2 channels of the Dx amplifier.
I am extremelly curious about.
Klaas is hardly busy...having small time those days...we will have his informs, i hope soon.
regards,
Carlos
Attachments
I had alot of trouble lapping one of the transistors... took forever to get it to lay flat... eventualy used asmall to220 heatsink on top of the transistors to help pull it flat...
Then I realised one of the pins is conected to the heatsink tab.... so I guess I will have to use those seethrough ceramic disks that came with the transistors... luckily there are 4...
Klaas, don't you think the back of you amp should be the top. to help with thermal dissipation....
Then I realised one of the pins is conected to the heatsink tab.... so I guess I will have to use those seethrough ceramic disks that came with the transistors... luckily there are 4...
Klaas, don't you think the back of you amp should be the top. to help with thermal dissipation....
It is very positive that you are extremelly carefull about those details Nordic.
Not flat transistors use to create enormous problems...many of them are bent in such a way that air bubbles are retained under the capsule...between the heatsinks and the transistor back.
This is one of the main cause of problems...i had so many that i cannot count.... but happened dozen of times.
Warped Chips use to produce problems too...very common in Panasonic Class H chip amplifiers... sanding and making it flat...return to work fine, without the protection entering and that damn relay clicking cutting your music... I do not remember if those chips were made by Panasonic..i think another factory was producing to Panasonic.
I do not think you must go to be a Gardener dear Klaas..compared with others that i was testimony of the mess they done, you are many times better...and those ones i was using as reference in my thougths, would not be a good gardener.
There are science to a Gardener too...as you know, you have that experience surrounding you...your country is a big garden as i know.... very old tradition related flowers.
But when we install amplifier boards into cases....many times, we start to have problems because of capacitances created from the lower ground place (the case) referenced to the board copper lines.
Ground loops happens usually.... not good solder joints in the ground can create a hell problems.... noises from the transformer and magnetic pickup from the nearby transformer...sometimes the amplifier has small input cap and low sensitivity, and we do not listen that hummm easy...but for sure they are affecting too.
Well.... sonner or latter you will find the guilty...if not...please, arrange a place to me in Holland.... i will be a gardner too.
regards,
Carlos
Not flat transistors use to create enormous problems...many of them are bent in such a way that air bubbles are retained under the capsule...between the heatsinks and the transistor back.
This is one of the main cause of problems...i had so many that i cannot count.... but happened dozen of times.
Warped Chips use to produce problems too...very common in Panasonic Class H chip amplifiers... sanding and making it flat...return to work fine, without the protection entering and that damn relay clicking cutting your music... I do not remember if those chips were made by Panasonic..i think another factory was producing to Panasonic.
I do not think you must go to be a Gardener dear Klaas..compared with others that i was testimony of the mess they done, you are many times better...and those ones i was using as reference in my thougths, would not be a good gardener.
There are science to a Gardener too...as you know, you have that experience surrounding you...your country is a big garden as i know.... very old tradition related flowers.
But when we install amplifier boards into cases....many times, we start to have problems because of capacitances created from the lower ground place (the case) referenced to the board copper lines.
Ground loops happens usually.... not good solder joints in the ground can create a hell problems.... noises from the transformer and magnetic pickup from the nearby transformer...sometimes the amplifier has small input cap and low sensitivity, and we do not listen that hummm easy...but for sure they are affecting too.
Well.... sonner or latter you will find the guilty...if not...please, arrange a place to me in Holland.... i will be a gardner too.
regards,
Carlos
If the suspect goes to the case..the heatsinks position or size.
The good test is to put a fan over it...a ventilator...well, to force it to run cool outside....it can be producing too much heat because of circuit problems...and even cooler the outside...the transistor may overheat.
If the amplifier continue beeing unstable. even forced to work cool....for sure the problems will be in the circuit.
regards,
Carlos
The good test is to put a fan over it...a ventilator...well, to force it to run cool outside....it can be producing too much heat because of circuit problems...and even cooler the outside...the transistor may overheat.
If the amplifier continue beeing unstable. even forced to work cool....for sure the problems will be in the circuit.
regards,
Carlos
I will use some computer thermal compound for that chip... too expensive to use on all 4, the cheap white stuff will have to do for the others...
Do the first transistor after diffirential pair need heatsinking too?
I put some DIY sinks pulled from a PC PSU and sawed smaller on the drivers... probably good for about 3 to 4W
I always enjoy the wireing the amp up part....useing the same power cable that is inside the walls of my house... just cant start with the case, until I know how big the transformers are, and I won't know until I get them, as they are custom... I guess about 15cm cubed...
Do the first transistor after diffirential pair need heatsinking too?
I put some DIY sinks pulled from a PC PSU and sawed smaller on the drivers... probably good for about 3 to 4W
I always enjoy the wireing the amp up part....useing the same power cable that is inside the walls of my house... just cant start with the case, until I know how big the transformers are, and I won't know until I get them, as they are custom... I guess about 15cm cubed...
Hi Klaas,
If you suspect oscillation place an AM portable radio very close beside the amp - not tuned to a station - and switch the amp on and off.
Do you hear anything at different frequencies ?
You could try increasing the VAS connected C.dom; try 47 to 100pF. The value necessary will depend upon devices being used.
Keep all output wires away from input, and keep source impedance low.
Is your heatsink grounded to the star point ? Should be !
Even experienced constructors can have oscillation problems, so don't be worried.
Cheers ......... Graham.
If you suspect oscillation place an AM portable radio very close beside the amp - not tuned to a station - and switch the amp on and off.
Do you hear anything at different frequencies ?
You could try increasing the VAS connected C.dom; try 47 to 100pF. The value necessary will depend upon devices being used.
Keep all output wires away from input, and keep source impedance low.
Is your heatsink grounded to the star point ? Should be !
Even experienced constructors can have oscillation problems, so don't be worried.
Cheers ......... Graham.
Dx amplifier can play using "unobtanium" input plugs
Also can receive audio from a "demagnetized" CD.....and it is the only one that will sound the same after those modifications done.
Only your pocket will be different...a little bit more empty.
Be free to change things into your amplifier...but do not believe that those modifications will always sound.
regards,
Carlos
Also can receive audio from a "demagnetized" CD.....and it is the only one that will sound the same after those modifications done.
Only your pocket will be different...a little bit more empty.
Be free to change things into your amplifier...but do not believe that those modifications will always sound.
regards,
Carlos
The problem i have with overheating is with both amps,
it has nothing to do with Greg's new pcb.
I'm sure the problem is somewhere in my build, i will investigate some of the things suggested but my time
is very limited the next days.
The heatsinks i'm using are the smaller ones i used earlier, they're about 0,87 c/w .
Best regards,
Klaas
it has nothing to do with Greg's new pcb.
I'm sure the problem is somewhere in my build, i will investigate some of the things suggested but my time
is very limited the next days.
The heatsinks i'm using are the smaller ones i used earlier, they're about 0,87 c/w .
Best regards,
Klaas
I would like to get my board ready for testing... I adjusted the bias pot to as far as it would go to 0, and the other trimpot to 7800R as per your instruction...
I know how to measure offset... DC multimeter on output...
But, what and where must I measure to set bias...? provided it doesnt go up in smoke on power up...
I know how to measure offset... DC multimeter on output...
But, what and where must I measure to set bias...? provided it doesnt go up in smoke on power up...
Instructions about adjustments are here
http://users.tpg.com.au/users/gerskine/dxamp/
regards,
Carlos
http://users.tpg.com.au/users/gerskine/dxamp/
regards,
Carlos
Use the fuses you have...and in parallel with them solder a very thin wire.
There are wires that has many units inside...and very thing....5 times smaller in diameter than a hair...the objective is to guarantee small resistance there...this small wire will burn with ...your fuse, the standard one placed, will have sligtly bigger current..it will burn with 300 miliamps more.
I told you to adjust trimpot to 6700 ohms...negative...better to adjust it to 4700 ohms.
It is better to use the VBE multiplier that i was posted, the one Michael Bittner suggested modifications...nothing more than an NPN transistor, can be a plastic unit, can be a TIP41...can be everyone you have..do not forget to insulate, as it will be attached into the heatsink.
The Vbe multiplier is a single transistor that senses temperature, it has a 2K resistance from Base to Colector (or two 1K units)...and a trimpot that connects the base and the emitter....this trimpot value, to adjust the stand by bias is 1K..and it will work fine beeing adjusted to 666 ohms...this will result in aproximatelly 50 miliamperes with the amplifier cold and with the input shorted.
I suggest you to substitute the 120 ohms resistance to a 180 ohms unit...this will give you more treble and will make drivers work more cold, needing smaller heatsinks.
The off set continue to be adjusted to 3 milivolts...this voltage do not fluctuate (variate) if your input was shorted.
Do not forget to remove the shorted input..
Install positive and negative resistances in series...for instance...33 ohms....you will read (adjusting) something around 1.5 volts over that resistance...also check the other rail...remember that positive rails is sligtly bigger the voltage developed over that 33 ohms, that means more current...this is because the zener diode current that is present in the positive rail and that is not present in the negative rail.
After bias adjustment and off set adjustment, do not forget to remove the protective resistances, also remove the input short, install speakers and be happy...ahahahha..very happy!
regards,
Carlos
There are wires that has many units inside...and very thing....5 times smaller in diameter than a hair...the objective is to guarantee small resistance there...this small wire will burn with ...your fuse, the standard one placed, will have sligtly bigger current..it will burn with 300 miliamps more.
I told you to adjust trimpot to 6700 ohms...negative...better to adjust it to 4700 ohms.
It is better to use the VBE multiplier that i was posted, the one Michael Bittner suggested modifications...nothing more than an NPN transistor, can be a plastic unit, can be a TIP41...can be everyone you have..do not forget to insulate, as it will be attached into the heatsink.
The Vbe multiplier is a single transistor that senses temperature, it has a 2K resistance from Base to Colector (or two 1K units)...and a trimpot that connects the base and the emitter....this trimpot value, to adjust the stand by bias is 1K..and it will work fine beeing adjusted to 666 ohms...this will result in aproximatelly 50 miliamperes with the amplifier cold and with the input shorted.
I suggest you to substitute the 120 ohms resistance to a 180 ohms unit...this will give you more treble and will make drivers work more cold, needing smaller heatsinks.
The off set continue to be adjusted to 3 milivolts...this voltage do not fluctuate (variate) if your input was shorted.
Do not forget to remove the shorted input..
Install positive and negative resistances in series...for instance...33 ohms....you will read (adjusting) something around 1.5 volts over that resistance...also check the other rail...remember that positive rails is sligtly bigger the voltage developed over that 33 ohms, that means more current...this is because the zener diode current that is present in the positive rail and that is not present in the negative rail.
After bias adjustment and off set adjustment, do not forget to remove the protective resistances, also remove the input short, install speakers and be happy...ahahahha..very happy!
regards,
Carlos
I have tried to burn the Dx amplifier...i made the most awfull things with my unit.
I could not destroy it....it is really stable and reliable.
I have installed hi speed transistors..trying to have oscilations...negative..no oscilations.
I made awfull wiring to the transistors...no oscilations.
I have injected 3 volts in the input..nothing burns.
I have worked by 20 minutes with full power..full distorted square waves..a very crazy signal that was driving more than 3 amps each rail...the output wire..the load resistance turns red for 20 minutes.
The Bittner VBE multipler worked very well....had better thermal tracking and controled the temperature very well.
As i have already posted.... the VBE multiplier is a NPN transistor attached into the heatsink...it has 2 K resistance from colector to base and a trimpot from base to emitter (1K)...adjusted to 666 ohms..this will result, aproximatelly 50 miliamperes of iddle bias...stand by current..with the amplifier cold and with the input shorted.
the off set could be ajusted to 2 milivolts and stay stable in the cold moments and the same voltage was observed when the amplifier was hot (nice that...very nice...and hard to obtain)
The off set trimpot, as already told in the last post made to Nordic, is a 10K unit, and it is adjusted to 4700 ohms when you start to adjust the offset.
The amplifier.... used that way reach 41 degrees centigrades and the temperature did not increase further.
When the heatsink was hot...the bias current was measured and was 72 miliamps...well...images i will post will show those things clearly.
I made modification into the 120 ohms resistance...also told in the last post made to Nordic...it is now 180 ohms, this distributed better the VBEs to output drivers and output units.... the current to drivers was reduced, than, they will work less hot...needing smaller heatsinks.
The VAS transistor had temperature measured and was 38 degrees celsius.
The environment temperature during testing were 28 degrees centigrades.
The load had a transformer primary in series with a monitor speaker to produce a low volume audio to monitoring only...the testing were made the highest possible distortions..and this time the output resistance was 6 ohms measured when hot.
The amplifier has enormous punch...reliable and stable in temperature..and now, much more stable, as it has Symassym VBE multiplier...ahahahahha.
Modifications will be informed in two images posted before the photos i have made during testings.
That resistance modified will be include in the home page..but if something goes wrong and the 120 ohms was to your circuit..not problems..will work fine..with a little less treble but will work fine.
No more important modification was one...except the iddle bias reduced to 40 or to 50 miliamps.
Also the inclusion of the VBE multiplier in the place of diodes..... the diodes will work fine too...but VBE multiplier is working perfectly.
regards,
Carlos
I could not destroy it....it is really stable and reliable.
I have installed hi speed transistors..trying to have oscilations...negative..no oscilations.
I made awfull wiring to the transistors...no oscilations.
I have injected 3 volts in the input..nothing burns.
I have worked by 20 minutes with full power..full distorted square waves..a very crazy signal that was driving more than 3 amps each rail...the output wire..the load resistance turns red for 20 minutes.
The Bittner VBE multipler worked very well....had better thermal tracking and controled the temperature very well.
As i have already posted.... the VBE multiplier is a NPN transistor attached into the heatsink...it has 2 K resistance from colector to base and a trimpot from base to emitter (1K)...adjusted to 666 ohms..this will result, aproximatelly 50 miliamperes of iddle bias...stand by current..with the amplifier cold and with the input shorted.
the off set could be ajusted to 2 milivolts and stay stable in the cold moments and the same voltage was observed when the amplifier was hot (nice that...very nice...and hard to obtain)
The off set trimpot, as already told in the last post made to Nordic, is a 10K unit, and it is adjusted to 4700 ohms when you start to adjust the offset.
The amplifier.... used that way reach 41 degrees centigrades and the temperature did not increase further.
When the heatsink was hot...the bias current was measured and was 72 miliamps...well...images i will post will show those things clearly.
I made modification into the 120 ohms resistance...also told in the last post made to Nordic...it is now 180 ohms, this distributed better the VBEs to output drivers and output units.... the current to drivers was reduced, than, they will work less hot...needing smaller heatsinks.
The VAS transistor had temperature measured and was 38 degrees celsius.
The environment temperature during testing were 28 degrees centigrades.
The load had a transformer primary in series with a monitor speaker to produce a low volume audio to monitoring only...the testing were made the highest possible distortions..and this time the output resistance was 6 ohms measured when hot.
The amplifier has enormous punch...reliable and stable in temperature..and now, much more stable, as it has Symassym VBE multiplier...ahahahahha.
Modifications will be informed in two images posted before the photos i have made during testings.
That resistance modified will be include in the home page..but if something goes wrong and the 120 ohms was to your circuit..not problems..will work fine..with a little less treble but will work fine.
No more important modification was one...except the iddle bias reduced to 40 or to 50 miliamps.
Also the inclusion of the VBE multiplier in the place of diodes..... the diodes will work fine too...but VBE multiplier is working perfectly.
regards,
Carlos
Attachments
My temperature meter was tested..you can see the tip touching the soldering iron
It is a 40 watts unit , made by Hikari Brasil, the name come from Korea that exported those soldering irons for us from 2000 to 2003..now it is made here.
You can see that the temperature is the one we spect.
regards,
Carlos
It is a 40 watts unit , made by Hikari Brasil, the name come from Korea that exported those soldering irons for us from 2000 to 2003..now it is made here.
You can see that the temperature is the one we spect.
regards,
Carlos
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