Dear benmanf,
Hi my name is David I am also 14 years old from Israel,
I would also like to build one of rode's amps!!
What I would like to know is where do you buy all your transistors and other parts?
I live in raanana and we don't have any shops that sell parts.
Could you tell me where to buy parts in Isreal?
It would be very helpfull
Thanks,
Kinser
Hi my name is David I am also 14 years old from Israel,
I would also like to build one of rode's amps!!
What I would like to know is where do you buy all your transistors and other parts?
I live in raanana and we don't have any shops that sell parts.
Could you tell me where to buy parts in Isreal?
It would be very helpfull
Thanks,
Kinser
carlos:
i think we both wrong, lol
i think they are fake, look:
some of the things show that they are fake and some show that they are real...
david:
no problem just give me your icq if you have...
i think we both wrong, lol
i think they are fake, look:
An externally hosted image should be here but it was not working when we last tested it.
some of the things show that they are fake and some show that they are real...
david:
no problem just give me your icq if you have...
Yes, good to use the heat grease.
And check if your heatsink has good size.....40 squared inches....multiply the sizes and calculate.
Reduce the bias.... check if VBE is lower then 600 mV.... reduce, try to adjust 550 milivolts, the output transistors VBE, voltage from base to emitter... without audio.... make a short circuit in the input to avoid noise.
Check again if you have some current over the emitter resistors.... can be 1, 2 or some milivolts.... good to be a current around 25mA to avoid heat... check if the amplifier is oscilating.... put your voltimeter in AC voltage, and measure over the speaker pins....no voltage can be found there...... now check if you have DC voltage in the output.... also over the speaker pins measure DC voltage.... can go from 1 milivolt to 100 milivolts without big problems...but if bigger....problem!
If heatsink small, put fan on them
If temperature different in transistor top, related to heatsink surface....bad heat conduction, bad heatsink or bad metal to metal junction.... check if some thin paper sheet can enter under the transistor.
regards,
good luck... is wonderfull hear our diy audio...isnt'it?
Carlos
And check if your heatsink has good size.....40 squared inches....multiply the sizes and calculate.
Reduce the bias.... check if VBE is lower then 600 mV.... reduce, try to adjust 550 milivolts, the output transistors VBE, voltage from base to emitter... without audio.... make a short circuit in the input to avoid noise.
Check again if you have some current over the emitter resistors.... can be 1, 2 or some milivolts.... good to be a current around 25mA to avoid heat... check if the amplifier is oscilating.... put your voltimeter in AC voltage, and measure over the speaker pins....no voltage can be found there...... now check if you have DC voltage in the output.... also over the speaker pins measure DC voltage.... can go from 1 milivolt to 100 milivolts without big problems...but if bigger....problem!
If heatsink small, put fan on them
If temperature different in transistor top, related to heatsink surface....bad heat conduction, bad heatsink or bad metal to metal junction.... check if some thin paper sheet can enter under the transistor.
regards,
good luck... is wonderfull hear our diy audio...isnt'it?
Carlos
Ooopps... looks like overbias does it again...
If you put 2 series 1A diodes in series between the base of Q5 & the base of Q6 it should limit the DC bias of the outputs, it will still be to high if Q9 is turned completely off but should be low enough not to melt the outputs down.
because otherwise if Q9 is turned off, the two outputs will saturate and BANG. This will help control the bias current and you will go through a lot less outputs and $$$$!!!!
(refer to my previous posts)
Good luck
Chris
BTW -- It can take a whole lot less time to melt down the transistors than the time it takes to break a fuse, even a fast acting fuse.
If you put 2 series 1A diodes in series between the base of Q5 & the base of Q6 it should limit the DC bias of the outputs, it will still be to high if Q9 is turned completely off but should be low enough not to melt the outputs down.
because otherwise if Q9 is turned off, the two outputs will saturate and BANG. This will help control the bias current and you will go through a lot less outputs and $$$$!!!!(refer to my previous posts)
Good luck
Chris
BTW -- It can take a whole lot less time to melt down the transistors than the time it takes to break a fuse, even a fast acting fuse.
I also whant to buil a P3A!!!!!!
Hi all,
I would like to know if the P3A amp output's 100 watts MAX a 4 ohms?
Rod wrote: "Operation into 4 ohm loads is not recommended with the 42V supplies. Peak dissipation will exceed 110W in each output transistor, leaving no safety margin with typical inductive loads..."
Then I was looking at the P3A construction guide and In the calculater:
INPUT: RESULTS:
Channels per transformer: 1 Rail voltage: 37.3
Power in Watts: 150 Transformer voltage VCT: 53.2
Load in Ohms: 4 Minimum VA: 214.3
R2R in Volts: 3 Can use 2955/3055?: no
I would like to get 100 to 150 watts at 4 ohm.... is it possible??
And if its possible what transistors must I use at the output stage??
What transformer?? (Rail voltage, VA...etc)
Thanks,
Kinser
Hi all,
I would like to know if the P3A amp output's 100 watts MAX a 4 ohms?
Rod wrote: "Operation into 4 ohm loads is not recommended with the 42V supplies. Peak dissipation will exceed 110W in each output transistor, leaving no safety margin with typical inductive loads..."
Then I was looking at the P3A construction guide and In the calculater:
INPUT: RESULTS:
Channels per transformer: 1 Rail voltage: 37.3
Power in Watts: 150 Transformer voltage VCT: 53.2
Load in Ohms: 4 Minimum VA: 214.3
R2R in Volts: 3 Can use 2955/3055?: no
I would like to get 100 to 150 watts at 4 ohm.... is it possible??
And if its possible what transistors must I use at the output stage??
What transformer?? (Rail voltage, VA...etc)
Thanks,
Kinser
Not with the P3A - the front end won't cope with higher voltages needed to get that much output power.
If you really want this much output power you are probably best off building the AmpsLab C200, but dont expect to be able to use 2955/3055's for it, they're too old for high power. Look for some MJ15003/4 transistors for this.
If you really want this much output power you are probably best off building the AmpsLab C200, but dont expect to be able to use 2955/3055's for it, they're too old for high power. Look for some MJ15003/4 transistors for this.
Want a demolition amplifier... earthquake... a hell destroyer.
An neigthboorhood vaporiser?.... one amplifier to crack your walls, to uscrew your speakers?... to turn you deef!
Write me and i will send you "the Killer".... the son of the thunder!... he thor hammer.... the vulcano explosion.
I am not responsible if your building had to be reconstructed!
Now talking serious..... not expensive.... not so easy to build...not so simple... wonderfull sound!... 180 RMS without distortion... can double easy this power.
But.... i am afraid will damage you ears if you like power.
Not the best...not the magnificent...not the golden sound.... only JLH designs makes golden sound!....but low powered units... good to frite eggs, or to make toats with bread.... wonderfull to hear too.
I have a zipped package, something, unfortunattely written in portuguese...but only follow the schematics... and beeing skilled, or having one skilled to follow you close, everything will be good... i cannot follow you close...and not expert too... only good ears...cannot use this amplifier....it can damage my ear.... to much power!
This one, is a Russian, old Soviet Politburo Kremlim design.... very good with brazilian modifications.... i remove all the Vodka and i put brazilian beverage as the poisoned condiment..... a hell amplifier.... very good Russian sound.... gooooood!... very gooood!
Carlos
An neigthboorhood vaporiser?.... one amplifier to crack your walls, to uscrew your speakers?... to turn you deef!
Write me and i will send you "the Killer".... the son of the thunder!... he thor hammer.... the vulcano explosion.
I am not responsible if your building had to be reconstructed!
Now talking serious..... not expensive.... not so easy to build...not so simple... wonderfull sound!... 180 RMS without distortion... can double easy this power.
But.... i am afraid will damage you ears if you like power.
Not the best...not the magnificent...not the golden sound.... only JLH designs makes golden sound!....but low powered units... good to frite eggs, or to make toats with bread.... wonderfull to hear too.
I have a zipped package, something, unfortunattely written in portuguese...but only follow the schematics... and beeing skilled, or having one skilled to follow you close, everything will be good... i cannot follow you close...and not expert too... only good ears...cannot use this amplifier....it can damage my ear.... to much power!
This one, is a Russian, old Soviet Politburo Kremlim design.... very good with brazilian modifications.... i remove all the Vodka and i put brazilian beverage as the poisoned condiment..... a hell amplifier.... very good Russian sound.... gooooood!... very gooood!
Carlos
hi kinser
if u really want a simple high power amp check Rods p68 at
http://sound.westhost.com/project68.htm
up to 500W rms
if u really want a simple high power amp check Rods p68 at
http://sound.westhost.com/project68.htm
up to 500W rms
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