Hi Folks, As a follow on from Sakis's thread
http://www.diyaudio.com/forums/showthread.php?s=&threadid=127039
I have reverse engineered a Chameleon 1400S so please find attached schematic.
Any odd looking values such as the Zobel resistor of 1R and 0R47 in parallel are how it is....
I don't have the original output transistors in Multisim so the MJL's are used instead. There is also some doubt over the varacity of the NE5534 model as compensation usually goes between pins 5 and 8 whereas only pins 1 and 5 are shown on the model.
I haven't yet had time to try out simulation of simple NE5534 circuitry on it's own and verify either that the Multisim model works correctly but mistakenly shows pin 8 as pin 1 or that it is not correct...
The simulation works great so long as you set the Zobel network values to be more "normal", it oscillates with the values used in the real thing, but the inductance of the 5 Watt wirewounds is not modeled (coudn't find any valid data on this believe it or not....non of the resistor manufacturers gives any figures for the self inductance of their wirewounds)
Also of course these are not the transistors used in the "real thing"
I'm guessing that the trimmer at the input is to match gain/phase at the inputs in order to get channel matching and best bridge mode performance (and yes, one end is left disconnected).
A brief check of distortion showed 0.005% at 1KHz and about 50 Watts output and -3dB at around 85KHz. These figures are just what I recall from late last night and not gospel truth, as it were..... It's only a simulation anyway so it could be out by a mile.
Jez.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=127039
I have reverse engineered a Chameleon 1400S so please find attached schematic.
Any odd looking values such as the Zobel resistor of 1R and 0R47 in parallel are how it is....
I don't have the original output transistors in Multisim so the MJL's are used instead. There is also some doubt over the varacity of the NE5534 model as compensation usually goes between pins 5 and 8 whereas only pins 1 and 5 are shown on the model.
I haven't yet had time to try out simulation of simple NE5534 circuitry on it's own and verify either that the Multisim model works correctly but mistakenly shows pin 8 as pin 1 or that it is not correct...
The simulation works great so long as you set the Zobel network values to be more "normal", it oscillates with the values used in the real thing, but the inductance of the 5 Watt wirewounds is not modeled (coudn't find any valid data on this believe it or not....non of the resistor manufacturers gives any figures for the self inductance of their wirewounds)
Also of course these are not the transistors used in the "real thing"
I'm guessing that the trimmer at the input is to match gain/phase at the inputs in order to get channel matching and best bridge mode performance (and yes, one end is left disconnected).
A brief check of distortion showed 0.005% at 1KHz and about 50 Watts output and -3dB at around 85KHz. These figures are just what I recall from late last night and not gospel truth, as it were..... It's only a simulation anyway so it could be out by a mile.
Jez.
The 5534 can stand a max of + and - 22 Volts, on many amps which have a simple zener diode arrangement using 15V zeners to give the op amp supplies, it is found that they actually measure anywhere from ABOUT 15.8 to 17.5 (very approximate!) because they are run "hot" (literally as well as meaning at a high current!) to give lower impedence and also the temp co is not goood.
I am guessing that your friend measured the supplies as 16.5 V on his amp. It is not in any way critical and I merely rounded it up to a whole number......same with the output stage supplies. I can't make actual measurements on the amp as it is not "a runner"
Jez.
I am guessing that your friend measured the supplies as 16.5 V on his amp. It is not in any way critical and I merely rounded it up to a whole number......same with the output stage supplies. I can't make actual measurements on the amp as it is not "a runner"
Jez.
real life tests
check this out ......
as we speak the amp is in real life test meaning ....board fully constructed heat sinked and ventilated
but:
Rails are 60+60 volts
1 khz sine wave + 8R dummy load
the only changes i have in the schematic is R22-23 = 52.3 R and R 27+26 = is now 10Kohm and emmiter resistors are 0.47 R
i have placed one millivolt meter across R12 emmiter resistor in one of the output transistors to monitor bias ......
here is what happend
with out the ventilator and with my electric thermo torch producing a lot of heat against the heat sink the bias increased from original reading about 70mv to something 90+ mv at this point got afraid and stopped ......
then added ventilator......... bias stabilized at 70mv at all times at this point no load ....
then added dummy load 1 khz sine and power up while still monitor the bias .....power up for 2 minutes at FULL power and then power down to monitor any changes in the bias ....
what happen is that the reading i had was some 45 milivolts that slowly slowly builted up to the original 70 mv
any comments ??????
check this out ......
as we speak the amp is in real life test meaning ....board fully constructed heat sinked and ventilated
but:
Rails are 60+60 volts
1 khz sine wave + 8R dummy load
the only changes i have in the schematic is R22-23 = 52.3 R and R 27+26 = is now 10Kohm and emmiter resistors are 0.47 R
i have placed one millivolt meter across R12 emmiter resistor in one of the output transistors to monitor bias ......
here is what happend
with out the ventilator and with my electric thermo torch producing a lot of heat against the heat sink the bias increased from original reading about 70mv to something 90+ mv at this point got afraid and stopped ......
then added ventilator......... bias stabilized at 70mv at all times at this point no load ....
then added dummy load 1 khz sine and power up while still monitor the bias .....power up for 2 minutes at FULL power and then power down to monitor any changes in the bias ....
what happen is that the reading i had was some 45 milivolts that slowly slowly builted up to the original 70 mv
any comments ??????
the above test
was done with the R26-27 moded from original 15K to 10 K to force more bias in the output transistors and then see or make bias drifts more obvious .....
some few minutes later the resistors R26-27 are back to normal 15K resulting only 1.1 mv across emmiter resistors that drifts more or less between 0.2-0.3 volts after operating the amp at full power for a few minutes ....( pls notice that all this is 1khz sine dummyload 8R and ventilator )
any comments ????
was done with the R26-27 moded from original 15K to 10 K to force more bias in the output transistors and then see or make bias drifts more obvious .....
some few minutes later the resistors R26-27 are back to normal 15K resulting only 1.1 mv across emmiter resistors that drifts more or less between 0.2-0.3 volts after operating the amp at full power for a few minutes ....( pls notice that all this is 1khz sine dummyload 8R and ventilator )
any comments ????
Sakis,
Do you have thermistor (R20 1K NTC in my diagram) fitted??
It is physically located in the centre of the output devices i.e. 3 devices to each side of it. The drivers are right at one end and quite long pcb tracks go from the driver area to the thermistor.
The output devices are arranged NPN PNP NPN PNP NPN PNP
in a row. R10 on my diagram appears to be a "select on test" (SOT) item, probably to set the initial quiescent current at the factory....?
Richie00boy,
They are Sanken 2SC3264 and 2SA1295 BJT's. See the schematic.
Jez.
Do you have thermistor (R20 1K NTC in my diagram) fitted??
It is physically located in the centre of the output devices i.e. 3 devices to each side of it. The drivers are right at one end and quite long pcb tracks go from the driver area to the thermistor.
The output devices are arranged NPN PNP NPN PNP NPN PNP
in a row. R10 on my diagram appears to be a "select on test" (SOT) item, probably to set the initial quiescent current at the factory....?
Richie00boy,
They are Sanken 2SC3264 and 2SA1295 BJT's. See the schematic.
Jez.
if things are correct
and the old and new schematic of the chameleons are correct ...then i thing i able to understand what the original designer had in mind about bias drift
particular amp is very effective i thing more than 65% so no matter how much power you ask from it it will get warm but not boiling hot so if the bias drifts abit then its ok
on the other hand of course version including thermistor should be more stable
been playing any way my version almost full power with speakers ( sound is fine nothing really impressive but very powerfull )
the heat sink is bearlly warm
and the old and new schematic of the chameleons are correct ...then i thing i able to understand what the original designer had in mind about bias drift
particular amp is very effective i thing more than 65% so no matter how much power you ask from it it will get warm but not boiling hot so if the bias drifts abit then its ok
on the other hand of course version including thermistor should be more stable
been playing any way my version almost full power with speakers ( sound is fine nothing really impressive but very powerfull )
the heat sink is bearlly warm
my version .....
worked out a complete night attached on a PA rig having some drums monitor duty ....
it was driving an kdw 151 15" monitor for all night .....
this test was done eventhough no thermistor was connected to 220R resitor ..... with a heat sink sized 12x22 and 12 cm ventilator on a top
watching levels and found out that amp was working at about 100% for more than 6 hours ( i presume that every time that kick drum was pressed you could notice the clip indicator blink so i think this was 100% ) and also this drummer was kinda power hungry in his monitor .....
the temparature builted up to 60 degrees on the heatsink and some times i had some variations but nothing more than 70 degrees
any day now i will test this in other pa application
still think that thermistor is needed as a safety isue eventhough if ventilator exists it seemed that wasnt needed
worked out a complete night attached on a PA rig having some drums monitor duty ....
it was driving an kdw 151 15" monitor for all night .....
this test was done eventhough no thermistor was connected to 220R resitor ..... with a heat sink sized 12x22 and 12 cm ventilator on a top
watching levels and found out that amp was working at about 100% for more than 6 hours ( i presume that every time that kick drum was pressed you could notice the clip indicator blink so i think this was 100% ) and also this drummer was kinda power hungry in his monitor .....
the temparature builted up to 60 degrees on the heatsink and some times i had some variations but nothing more than 70 degrees
any day now i will test this in other pa application
still think that thermistor is needed as a safety isue eventhough if ventilator exists it seemed that wasnt needed
I have as spy from the Athens audio club that made copies on
your vacation pictures Sakis.
It seems you have enjoyed.
My Athens spy, very acid guy, said you have just got out from the jail.... carefull with your surroundings, Dx spies are everywhere.... this one got Maria's picture too.... congratulations Sakis....Maria is very pretty.
regards to you and Maria.
be good in your heart Sakis... be happy....be healthy!
Carlos
your vacation pictures Sakis.
It seems you have enjoyed.
My Athens spy, very acid guy, said you have just got out from the jail.... carefull with your surroundings, Dx spies are everywhere.... this one got Maria's picture too.... congratulations Sakis....Maria is very pretty.
regards to you and Maria.
be good in your heart Sakis... be happy....be healthy!
Carlos
Attachments
small details
i havent listen the amp extensivelly i only had the chance to listen to it in a good ammount of power yesterday in my lab for a couple of hours ....and then directly install it in the live show i had to run last night .....
the drummer that listen to it for all night was very happy with the power (( arround 180W with 63+63 rails )) he said to me tha kick drum sounded really very tight and rich ....snare drum kinda deep ( not really that bright ) and the rest of the percussion was ok mostly as we say flat and without any brightness in high ....
my impression(( after listening to music in good power for a couple of hours )) very rich in bass with a very good ammount of headroom but something like confusing in high ....
my final opinion is that the amp is average may be lower than that but compaired the simplicity is made i thing is PERFECTO !!!!!
for a simple PA application low cost and simplicity to make is hell of a nice equipment to have
jez said:
i havent listen the amp extensivelly i only had the chance to listen to it in a good ammount of power yesterday in my lab for a couple of hours ....and then directly install it in the live show i had to run last night .....
the drummer that listen to it for all night was very happy with the power (( arround 180W with 63+63 rails )) he said to me tha kick drum sounded really very tight and rich ....snare drum kinda deep ( not really that bright ) and the rest of the percussion was ok mostly as we say flat and without any brightness in high ....
my impression(( after listening to music in good power for a couple of hours )) very rich in bass with a very good ammount of headroom but something like confusing in high ....
my final opinion is that the amp is average may be lower than that but compaired the simplicity is made i thing is PERFECTO !!!!!
for a simple PA application low cost and simplicity to make is hell of a nice equipment to have
another thing
in the particullar application i forgot to mention that the amplifier was housed in a box that used to be an Acoustica amplifier so the psu existing inside allready
meaning that trafo and psu produced 63+63 voltDC rails ,trafo rated @350W and banks inside was 10.500mfd per rail caps ( 10 years old)
this was available at the time of construction enough more or less
new pcb ( with one set of transistors more , option for base resistors and a few other small mods together with my PIGGY BOARD !!!!is allready in the pcb shop ) since id like to make a 80 +80 volts version in existing ALTAIR box that i have in my shop
REGARDS SAKIS
in the particullar application i forgot to mention that the amplifier was housed in a box that used to be an Acoustica amplifier so the psu existing inside allready
meaning that trafo and psu produced 63+63 voltDC rails ,trafo rated @350W and banks inside was 10.500mfd per rail caps ( 10 years old)
this was available at the time of construction enough more or less
new pcb ( with one set of transistors more , option for base resistors and a few other small mods together with my PIGGY BOARD !!!!is allready in the pcb shop ) since id like to make a 80 +80 volts version in existing ALTAIR box that i have in my shop
REGARDS SAKIS
I see you have enougth knowledge and doing very well
Amplifier is sounding fine and having good test reviews by yourself.
- "drum kicks are powerfull"
Increase heatsinks and keep stand by current, into emitter resistances, to 1 or 2 milivolt reading without signal.... to each one of them.
Increase your heatsink size, because 70 degrées celsius is too much..try to reduce it to 50 degrées.
When you have 70 degrées celsius into the heatsink, the junction is near to be melted because of bigger temperature.
Operating into this temperature you have the risk to loose transistors...to have a shorted output.
Transistor power is measured into 25 degrées celsius... they maintain the unit cold to measure... when temperature rises, the transistor change a lot of characteristics.... no specifications are true when you drive them hard...everything changes...into the worse direction.
Good luck,
Carlos
Amplifier is sounding fine and having good test reviews by yourself.
- "drum kicks are powerfull"
Increase heatsinks and keep stand by current, into emitter resistances, to 1 or 2 milivolt reading without signal.... to each one of them.
Increase your heatsink size, because 70 degrées celsius is too much..try to reduce it to 50 degrées.
When you have 70 degrées celsius into the heatsink, the junction is near to be melted because of bigger temperature.
Operating into this temperature you have the risk to loose transistors...to have a shorted output.
Transistor power is measured into 25 degrées celsius... they maintain the unit cold to measure... when temperature rises, the transistor change a lot of characteristics.... no specifications are true when you drive them hard...everything changes...into the worse direction.
Good luck,
Carlos
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