No my dear Andrew Now goodbuyer, as have bougth the Dx Amplifier idea!
So, now you're a good buyer..hehehehe
I have not tried those ones Andrew.
I am not very addicted to chip amplifiers...i know they have some advantage, and my bad english use the same pronouce to chip and cheap..ahahaha..so...they are almost the same in my mind.
Cheap is good.....so..... my brain accept chip as good too, because the sound they make into my tongue is the same..hehehehe..
But also, life shown me that is very rare to have cheap things that are very good too... the exception is our forum group buy....the boards are very cheap and parts are bougth by the cost price...and the work is made by our diyers.....so.... one of the rarities we have in our lives.... cheap and good...only our forum with group buy.
regards,
Carlos
So, now you're a good buyer..hehehehe
I have not tried those ones Andrew.
I am not very addicted to chip amplifiers...i know they have some advantage, and my bad english use the same pronouce to chip and cheap..ahahaha..so...they are almost the same in my mind.
Cheap is good.....so..... my brain accept chip as good too, because the sound they make into my tongue is the same..hehehehe..
But also, life shown me that is very rare to have cheap things that are very good too... the exception is our forum group buy....the boards are very cheap and parts are bougth by the cost price...and the work is made by our diyers.....so.... one of the rarities we have in our lives.... cheap and good...only our forum with group buy.
regards,
Carlos
Ok
Thanks Carlos
Well I guess I'll re-use the parts.
I will be building HRII soon, will post pictures in the big thread if I can borrow a camera.
I will probably have questions for you.
p.s. The STK chip amp sounded cold, boring. But the bass was Very good. On some songs/tracks it was very good -- weird huh? THD was low.
See Ya!
Thanks Carlos
Well I guess I'll re-use the parts.
I will be building HRII soon, will post pictures in the big thread if I can borrow a camera.
I will probably have questions for you.
p.s. The STK chip amp sounded cold, boring. But the bass was Very good. On some songs/tracks it was very good -- weird huh? THD was low.
See Ya!
Thats why I bought 3 🙂
I am excited to figure out what subwoofer I am going to power with the third 🙂
I am excited to figure out what subwoofer I am going to power with the third 🙂
Nordic or Carlos,
Wich output drivers could be used without changing the values of the other components?
Wich output drivers could be used without changing the values of the other components?
Hi Meany, you would have to give more details...
But I guess as long as the transistor is good enough for the voltages it sees it should be ok.. Also try to avoid high speed transistors.
For HRII, the common bd139/bd140 works perfectly.
But I guess as long as the transistor is good enough for the voltages it sees it should be ok.. Also try to avoid high speed transistors.
For HRII, the common bd139/bd140 works perfectly.
Use BD139 or TIP41/42, as those ones are the standard hardly tested
I have tried many others, and found the amplifier less stable.
MJ15032 into the VAS position made it unstable...into driver position had oscilations triggered by the signal.
I strongly suggest you to keep the schematic the way it is for safety reasons.
The way it is you have the guarantee of many units tested and built, using others, we cannot guarantee stability or reliability, as during tests i found problems using TIP35 into the output and some other transistor had problems too.
Very High Frequency units were tested into the differential and worked very bad, also they had lower gain compared to BC556 (for instance) that can have, sometimes, 550 of gain.
BD139 was used, since the seventies, in thousand of models and brands, even their cousines, MJE350/340 are not so reliable and so well accepted, had not the same reliability fame.
If you can, please, search for BD139 and BD140... they are already high speed, so, you gonna have good performance, but it is stable, has not enormous gain, but normally goes around 100, and this is more than enougth as drivers and VAS, were 50 of gain is already good.... those transistors are used, also into Radio Frequency transmitters, as they are able to oscilate (operate) into 100 Megahertz without too much losses.
Cannot find them, try Nordic, or try MJE340 and MJE350, and check the datasheet to see if leads are the same..... i have NOT tested those MJE340 and 350, so, i cannot guarantee they will operate fine...i suppose they will, but i have not sure.
You have bigger plastic option, the 2SC4793 and 2SA1837, mine most beloved transistors...those are stable and i have tested with them...but they are TO220 and looks very ugly and enormous compared to the board size.
regards,
Carlos
I have tried many others, and found the amplifier less stable.
MJ15032 into the VAS position made it unstable...into driver position had oscilations triggered by the signal.
I strongly suggest you to keep the schematic the way it is for safety reasons.
The way it is you have the guarantee of many units tested and built, using others, we cannot guarantee stability or reliability, as during tests i found problems using TIP35 into the output and some other transistor had problems too.
Very High Frequency units were tested into the differential and worked very bad, also they had lower gain compared to BC556 (for instance) that can have, sometimes, 550 of gain.
BD139 was used, since the seventies, in thousand of models and brands, even their cousines, MJE350/340 are not so reliable and so well accepted, had not the same reliability fame.
If you can, please, search for BD139 and BD140... they are already high speed, so, you gonna have good performance, but it is stable, has not enormous gain, but normally goes around 100, and this is more than enougth as drivers and VAS, were 50 of gain is already good.... those transistors are used, also into Radio Frequency transmitters, as they are able to oscilate (operate) into 100 Megahertz without too much losses.
Cannot find them, try Nordic, or try MJE340 and MJE350, and check the datasheet to see if leads are the same..... i have NOT tested those MJE340 and 350, so, i cannot guarantee they will operate fine...i suppose they will, but i have not sure.
You have bigger plastic option, the 2SC4793 and 2SA1837, mine most beloved transistors...those are stable and i have tested with them...but they are TO220 and looks very ugly and enormous compared to the board size.
regards,
Carlos
Sorry Nordic,I ment the output transistors 2SC5200 and the 2SA1943 are their equal replacements for those?Nordic said:
Carlos,
Wich one do you prefer regarding sound-quality
2SC3858- 2SA1494 or 2SC5200- 2SA1943?
Is there a difference in sound at all?
Wich one do you prefer regarding sound-quality
2SC3858- 2SA1494 or 2SC5200- 2SA1943?
Is there a difference in sound at all?
Transistors do not sound different, they sound almost the same
the difference is the frequency limit, some of them seems to reproduce sligthly better the top high end of frequencies.
I think this may be illusion, we self convince ourselves...self brain wash, as those differences of performance happens, in the reality, into very high frequencies, above the human audibility...so...it is more a matter of illusion than reality.
I use to "perceive" my Sankens as better sounding devices into the high end.... i can see, when this happens, our capacity of self brain wash..... those things are more connected to love and passion than to real things.
A little bit more gain is not perceived, we cannot perceive that.... we only perceive big differences of power.
Transistors have gain, maximum voltage, maximum dissipation... those characteristics are the important ones..... them you have price, shape, size, how pretty they are and subjective things alike.
- "The one you like"
I have not listened those others.... i think they will sound almost the same...... but.... if you have some "belief", better to follow your ideas, as you may feel more same using the units you trust.
When we replace a transistor, and the spectations are to find something different...of course you will find something different.... this is "previous decisions taken".... having not a reference, we believe into the things we want to believe.
Of course, if you switch them to A to B testing, or use 2 amplifiers, one using pair transistor "A" and other using pair transistor "B", then you will see was illusion.
regards,
Carlos
the difference is the frequency limit, some of them seems to reproduce sligthly better the top high end of frequencies.
I think this may be illusion, we self convince ourselves...self brain wash, as those differences of performance happens, in the reality, into very high frequencies, above the human audibility...so...it is more a matter of illusion than reality.
I use to "perceive" my Sankens as better sounding devices into the high end.... i can see, when this happens, our capacity of self brain wash..... those things are more connected to love and passion than to real things.
A little bit more gain is not perceived, we cannot perceive that.... we only perceive big differences of power.
Transistors have gain, maximum voltage, maximum dissipation... those characteristics are the important ones..... them you have price, shape, size, how pretty they are and subjective things alike.
- "The one you like"
I have not listened those others.... i think they will sound almost the same...... but.... if you have some "belief", better to follow your ideas, as you may feel more same using the units you trust.
When we replace a transistor, and the spectations are to find something different...of course you will find something different.... this is "previous decisions taken".... having not a reference, we believe into the things we want to believe.
Of course, if you switch them to A to B testing, or use 2 amplifiers, one using pair transistor "A" and other using pair transistor "B", then you will see was illusion.
regards,
Carlos
2SA1943 and 2SC5200 both dissipate 150 watts at 25 degrees C ambient while BD139 and BD140 each dissipate 12.5 watts. For a total of 387.5 watts. This cant be right. This is the max that could be dissipated by these devices and the biggest ones can run at 15 amps. We will be running them at around 3 amps, right? So can I divide the 387.5 watts by 5 since 3 amps is one fifth of 15? Then size my heatsink for about 75 watts at 25 degrees C ambient?
I am not sure of how you calculated that Uriah...
My rough calculation says you need a sink between 80 and 100W,
Yes meany, I don't forsee any problems.
My rough calculation says you need a sink between 80 and 100W,
Yes meany, I don't forsee any problems.
Well, the 387 is how many watts of heat are dissipated by each channel driven at the full capability of the transistors. Since we are NOT driving them at full power but, I think, at about 1/5th their rated power then I divided 387 by 5 and you get approximately 75 watts. I didnt know if I was on the right track or not, but when you say you estimate 80-100 then I think I was doing alright estimating.
The two larger transistors dissipate 150 each at full power = 300
The NPN and PNPs dissipate 12.5 each at full power = 87.5
So 387.5 at full power and thats at 15 amps. We are driving at a max of 3 amps I think (guessing). 15/3=5 so 387/5=77.5 So I figure we need a heatsink to get rid of 77.5 watts per channel to keep it at 25 degrees C.
This was just my guess but I wasnt sure if I was anywhere close, thats why I was asking what you thought.
The two larger transistors dissipate 150 each at full power = 300
The NPN and PNPs dissipate 12.5 each at full power = 87.5
So 387.5 at full power and thats at 15 amps. We are driving at a max of 3 amps I think (guessing). 15/3=5 so 387/5=77.5 So I figure we need a heatsink to get rid of 77.5 watts per channel to keep it at 25 degrees C.
This was just my guess but I wasnt sure if I was anywhere close, thats why I was asking what you thought.
Hi,
it's far easier to use the worst case dissipation @~=60% of maximum output power.
Then apply the thermal resistances to find the device case temperatures (Tc) with your chosen heatsink and finally determine the temperature de-rated SOA for your chosen devices and decide if 3A overloads them or not.
BTW,
3A is very low for an output current into a reactive load.
it's far easier to use the worst case dissipation @~=60% of maximum output power.
Then apply the thermal resistances to find the device case temperatures (Tc) with your chosen heatsink and finally determine the temperature de-rated SOA for your chosen devices and decide if 3A overloads them or not.
BTW,
3A is very low for an output current into a reactive load.
Nordic,
I was looking at the part-list and came across C6 with value 2µ2 but where is X standing for?I can't find it on the board or schematic.
I was looking at the part-list and came across C6 with value 2µ2 but where is X standing for?I can't find it on the board or schematic.
Strange, just from memory, not quite awake yet...
But I think you may be looking at C8 which is 2n2?
But I think you may be looking at C8 which is 2n2?
I am using the schematic from DXAMP site. On this schematic C6 is 2n2 or 2.2nanofarads.
If you are using the Greg Erskine schematic many of the values/part numbering are different.
If you are using the Greg Erskine schematic many of the values/part numbering are different.
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