The Bias transistor, attached to the heatsink may work fine to compensate thermal
drift dear Space..... i think will not need negative thermistance .... thermal resistance not needed...the bias transistor junction will hold this job...make it tigth, with good thermal grease...good thermal contact into the heatsink and i think you gonna be happy.
regards,
Carlos
drift dear Space..... i think will not need negative thermistance .... thermal resistance not needed...the bias transistor junction will hold this job...make it tigth, with good thermal grease...good thermal contact into the heatsink and i think you gonna be happy.
regards,
Carlos
hi,
my amp is now working well. no problem i am facing now. everyday i am operating to see if there is any problem find.
anyway it is ok now....lets see....hope should be ok...
sound really gooooooooooooooooooooooooooooooood....sweet...
**why i like few pair output transistors type amp bcse of the hi fidelity? driving power is strong enough to make sound more life. i don't know the wats related or not....it's nice to listen when use few pair of tranasistors on the out put stage.
thank you.
my amp is now working well. no problem i am facing now. everyday i am operating to see if there is any problem find.
anyway it is ok now....lets see....hope should be ok...
sound really gooooooooooooooooooooooooooooooood....sweet...
**why i like few pair output transistors type amp bcse of the hi fidelity? driving power is strong enough to make sound more life. i don't know the wats related or not....it's nice to listen when use few pair of tranasistors on the out put stage.
thank you.
hi,
update for precision I. it is working find until now. no more over heat problem.
i want to ask one question, can i use 4 ohms or 6 ohms speaker in it?
as i have seen there are three pair of transistor so souldn't be problem using 4 or 6 ohms speaker right?
thanks
update for precision I. it is working find until now. no more over heat problem.
i want to ask one question, can i use 4 ohms or 6 ohms speaker in it?
as i have seen there are three pair of transistor so souldn't be problem using 4 or 6 ohms speaker right?
thanks
So has anyone other than Michael got one working?
What does it sound like? Come on! Some arm's length comparisons would be nice!
Me? I won't be building for ages as I have a SKA, an Aikido and a pair of Zaph's Waveguides to do first...
Cheers
Stuey
What does it sound like? Come on! Some arm's length comparisons would be nice!
Me? I won't be building for ages as I have a SKA, an Aikido and a pair of Zaph's Waveguides to do first...
Cheers
Stuey
hehehe... we need to find a way to wake up those folks
they are too much silent.
regards,
Carlos
they are too much silent.
regards,
Carlos
This is good fardo...please... send me pictures showing the production steps
panzertoo@yahoo.com
You pictures may stimulate (and wake up) others.
regards,
Carlos
panzertoo@yahoo.com
You pictures may stimulate (and wake up) others.
regards,
Carlos
Will do
Main concern is resourcing heatsinks. Also will browse back through this thread to check last components upgrades.
Cheers. Abraços . Destroyer, Nordic
Main concern is resourcing heatsinks. Also will browse back through this thread to check last components upgrades.
Cheers. Abraços . Destroyer, Nordic
bias problem
hi frnds,
I have built one channel of HR1 but having problem with it. I ran it with 30-0-30 for testing purpose with 10ohm resistor installed in both rails. DC offset is about 1mv. With maximum resistance of the trimpot i.e 500ohms i measured the volts across .33ohm emitter resistor which was abt 100mv and the output devices,3 pairs are becoming a lil bit warm. With rails resistor installed i gave the input music signal and the output was clear and undistorted at low volume. But at this stage i m afraid of running it with 63-0-63 since the idle voltage is not coming down from 100mv. I checked all the resistor values and transistor pinning and everything seems to be ok.
Plzzzz.... help me as i m out or ideas or is it normal with this amp. I ll post pictures later.The pcb is homemade and the only change i made is that i used BC547B instead of "C" as it was not available in the local market.
regards, Aman
hi frnds,
I have built one channel of HR1 but having problem with it. I ran it with 30-0-30 for testing purpose with 10ohm resistor installed in both rails. DC offset is about 1mv. With maximum resistance of the trimpot i.e 500ohms i measured the volts across .33ohm emitter resistor which was abt 100mv and the output devices,3 pairs are becoming a lil bit warm. With rails resistor installed i gave the input music signal and the output was clear and undistorted at low volume. But at this stage i m afraid of running it with 63-0-63 since the idle voltage is not coming down from 100mv. I checked all the resistor values and transistor pinning and everything seems to be ok.
Plzzzz.... help me as i m out or ideas or is it normal with this amp. I ll post pictures later.The pcb is homemade and the only change i made is that i used BC547B instead of "C" as it was not available in the local market.
regards, Aman
Vre=100mV is far too high.
It will be even higher when you increase the supply voltage.
You must find the error in the Vbe multiplier before you proceed.
It will be even higher when you increase the supply voltage.
You must find the error in the Vbe multiplier before you proceed.
The Precision 1 does not operate well using such low voltage
Produce your tests again with higher voltage and them start your evaluation/debugging
Carlos
Produce your tests again with higher voltage and them start your evaluation/debugging
Carlos
Questions regarding DX Precision I amplifier
Hello, my name is Michael and I'm from Romania (Europe). I've recently found the "Precision I" schematic as I was browsing through diyAudio forums and decided that I would try to build it sometime this summer. Altough there seems to be plenty of information about it, I didn't find some answers regarding several aspects and I was wondering if somebody is kind enough to share some insight about the amplifier. I did try to contact mr. Carlos via e-mail several times, but didn't get any feedback, so here I am... I do have some questions:
1. Is the version published on "dxamp.com" the last one or are there newer revisions? If so, where can I find them?
2. What is the actual (recommended) bias current (through 0.33 resistors)? I usually set bias current by measuring the voltage across the emitter resistors wich tells me the exact current that flows through each transistor. So, what is the recommended value? I can't seem to find this.
3. The input capacitor (4u7) is a bipolar one? There was a discussion regarding the value... Is this the final one?
4. Should I ommit something from the schematic... since there was a debate about the two diodes near the input (D1, D2) and how they might affect stability? Anything else?
5. What are the fuse ratings (both 4 and 8 ohms versions, both rail and output)?
6. What is the required rating for the transformer (1 transformer for 2 channels, both 4 and 8 ohms)? How about the total capacitance required?
7. What is the rating for the heatsink (the thermal resistance required) - so I can build/design my own?
8. What are the electrical parameters of the amplifier: output power, output impedance, input sensitivity, input impedance, bandwidth, slew rate, SNR, THD, TID, damping factor, etc?
9. Can this amplifier be used for "full range" reproduction? Does it have a "linear" response or does it have a "soft spot" for certain frequency ranges (ex: does it reproduce better mids than bass)?
10. Is the amplifier stable when using long cables to connect the speakers? How about when using 2 or 3 way passive crossovers?
11. As I've noticed, there is no short-circuit protection (current limiting)? Is this intended? I assume that the amplifier will "blow" in case of a short-circuit on output (I really don't trust fuses on output). Can I add something like a VI limiter to ensure current limiting in case of a fault? Can anybody recommend something? What is the max. output current and what threshold would one recommend?
12. Can the offset be adjusted?
I would really appreciate any help. Thanks in advance,
Michael.
Hello, my name is Michael and I'm from Romania (Europe). I've recently found the "Precision I" schematic as I was browsing through diyAudio forums and decided that I would try to build it sometime this summer. Altough there seems to be plenty of information about it, I didn't find some answers regarding several aspects and I was wondering if somebody is kind enough to share some insight about the amplifier. I did try to contact mr. Carlos via e-mail several times, but didn't get any feedback, so here I am... I do have some questions:
1. Is the version published on "dxamp.com" the last one or are there newer revisions? If so, where can I find them?
2. What is the actual (recommended) bias current (through 0.33 resistors)? I usually set bias current by measuring the voltage across the emitter resistors wich tells me the exact current that flows through each transistor. So, what is the recommended value? I can't seem to find this.
3. The input capacitor (4u7) is a bipolar one? There was a discussion regarding the value... Is this the final one?
4. Should I ommit something from the schematic... since there was a debate about the two diodes near the input (D1, D2) and how they might affect stability? Anything else?
5. What are the fuse ratings (both 4 and 8 ohms versions, both rail and output)?
6. What is the required rating for the transformer (1 transformer for 2 channels, both 4 and 8 ohms)? How about the total capacitance required?
7. What is the rating for the heatsink (the thermal resistance required) - so I can build/design my own?
8. What are the electrical parameters of the amplifier: output power, output impedance, input sensitivity, input impedance, bandwidth, slew rate, SNR, THD, TID, damping factor, etc?
9. Can this amplifier be used for "full range" reproduction? Does it have a "linear" response or does it have a "soft spot" for certain frequency ranges (ex: does it reproduce better mids than bass)?
10. Is the amplifier stable when using long cables to connect the speakers? How about when using 2 or 3 way passive crossovers?
11. As I've noticed, there is no short-circuit protection (current limiting)? Is this intended? I assume that the amplifier will "blow" in case of a short-circuit on output (I really don't trust fuses on output). Can I add something like a VI limiter to ensure current limiting in case of a fault? Can anybody recommend something? What is the max. output current and what threshold would one recommend?
12. Can the offset be adjusted?
I would really appreciate any help. Thanks in advance,
Michael.
Informations about were posted, at least the most important ones
If something was missed, after your reading, please, return to ask something needed.
Things that had discussions are up to you to decide by yourself.
There's a schematic into www.dxamp.com
I do not have measurements.... if you need them, a better idea is to try Mihai Rauna amplifier, published in this same forum... a great amplifier, also a glory for measurements.
I think all those informations were discussed into the Dx Amplifier thread and also in this one.... not a good idea to repeat all that, when was already posted with the intention to avoid me to answer each one that have doubts... so doubts are there... if there's an exception, something missed...i am here to help...and also into:
panzertoo@yahoo.com
here you have one adress about the Dx Amplifiers:
http://users.tpg.com.au/users/gerskine/dxamp/
Roender amplifier is perfect for measurements, and also sounds great.. i have assembled and listened.... as i have not the specifications (complete) about the Precision, and this because i do not bother about numbers, and you may believe in that stuff, a good idea is to assemble Roender's amplifier... this one sounds good and have all the informations about specification you may want.
I have few specifications
Frequency response from 10 herts to 100 Kilohertz -3dB
Sensitivity... 750 milivolts rms will drive the amplifier full power (adjustable)
150 and 256 watts rms, continuous, sinusoidal signal entering into the frequency of 1 Kilohertz, unclipped over loads of 8 and 4 ohms.
Damping.... good enougth
Distortion...low enougth
THD.... may be reasonable
IMD... for sure not bad
Noise.... very low, almost unlistenable
But Roender amplifier is technically superior...and has all numbers you may want... a very small distortion that may represent the "hell of the meter equipments"...the instruments may feel very frustrated not finding big distortion numbers there.
I do not believe that equipments that measure very good have to sound very good...they can sound good or bad.... Symassym and Roender amplifiers are the ones i know measure very well and sounds very well too...and i have assembled and listened both and i felt them very good.
Also my amplifiers sounds very good...the difference is that i have not measured them...not curious about.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=111756
regards,
Carlos
If something was missed, after your reading, please, return to ask something needed.
Things that had discussions are up to you to decide by yourself.
There's a schematic into www.dxamp.com
I do not have measurements.... if you need them, a better idea is to try Mihai Rauna amplifier, published in this same forum... a great amplifier, also a glory for measurements.
I think all those informations were discussed into the Dx Amplifier thread and also in this one.... not a good idea to repeat all that, when was already posted with the intention to avoid me to answer each one that have doubts... so doubts are there... if there's an exception, something missed...i am here to help...and also into:
panzertoo@yahoo.com
here you have one adress about the Dx Amplifiers:
http://users.tpg.com.au/users/gerskine/dxamp/
Roender amplifier is perfect for measurements, and also sounds great.. i have assembled and listened.... as i have not the specifications (complete) about the Precision, and this because i do not bother about numbers, and you may believe in that stuff, a good idea is to assemble Roender's amplifier... this one sounds good and have all the informations about specification you may want.
I have few specifications
Frequency response from 10 herts to 100 Kilohertz -3dB
Sensitivity... 750 milivolts rms will drive the amplifier full power (adjustable)
150 and 256 watts rms, continuous, sinusoidal signal entering into the frequency of 1 Kilohertz, unclipped over loads of 8 and 4 ohms.
Damping.... good enougth
Distortion...low enougth
THD.... may be reasonable
IMD... for sure not bad
Noise.... very low, almost unlistenable
But Roender amplifier is technically superior...and has all numbers you may want... a very small distortion that may represent the "hell of the meter equipments"...the instruments may feel very frustrated not finding big distortion numbers there.
I do not believe that equipments that measure very good have to sound very good...they can sound good or bad.... Symassym and Roender amplifiers are the ones i know measure very well and sounds very well too...and i have assembled and listened both and i felt them very good.
Also my amplifiers sounds very good...the difference is that i have not measured them...not curious about.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=111756
regards,
Carlos
Fuses for Precision I can be those ones.
for 8 ohms use 2.5 amperes to each rail and 5 amperes into the output.
for 4 ohms use 5 amperes to each rail and 10 amperes into the output.
Why can be?
Supply use to have voltage drop.... so... power into the rails and into the output will be smaller...so... fuses may be overkill.
People can listen into the distortion, and this means more current than the one you have while listening into the threshold of clipping... those fuses are for a little bit more than the threshold of clipping...but cannot hold full clipped power.
So.... again a matter of decision...if you want a value...install the ones suggested first...but the reality will decide..have to engage brain and think about your sound needs, your speakers, your kind of music and if you like distortions or not.
regards,
Carlos
for 8 ohms use 2.5 amperes to each rail and 5 amperes into the output.
for 4 ohms use 5 amperes to each rail and 10 amperes into the output.
Why can be?
Supply use to have voltage drop.... so... power into the rails and into the output will be smaller...so... fuses may be overkill.
People can listen into the distortion, and this means more current than the one you have while listening into the threshold of clipping... those fuses are for a little bit more than the threshold of clipping...but cannot hold full clipped power.
So.... again a matter of decision...if you want a value...install the ones suggested first...but the reality will decide..have to engage brain and think about your sound needs, your speakers, your kind of music and if you like distortions or not.
regards,
Carlos
Re: Fuses for Precision I can be those ones.
But you may find that the smaller ones do not suffer from nuisance blowing even with high power transients.
a very good answer that deserves committing to memory. (Carlos, please excuse the corrections)destroyer X said:
I would recommend slightly higher rated rail fuses. F3A and F6A.destroyer X said:
But you may find that the smaller ones do not suffer from nuisance blowing even with high power transients.
Hello Carlos,
That reads like a Rolls-Royce specification of a few years back. They NEVER quoted performance figures.
Power output ---- adequate
Torque------------adequate
😀 😀
That reads like a Rolls-Royce specification of a few years back. They NEVER quoted performance figures.
Power output ---- adequate
Torque------------adequate
😀 😀
Yes.... i remember that very well.
I used to read many automobile magazines, also Popular Electronics and Popular Mechanics since the sixties.... i know those things from Rolls and Royce.
I had a beetle for 10 years long...no one have touched on it...i was the repair man.
Also i had a Dodge Charger... this one i have need some help.
Roll and Royce have told the true...also my amplifier is truly a very good unit.
Automobiles, cars was a passion to me, also my daugthers, audio electronics, tape recorders , Radio Amateur and Chocolate.
regards,
Carlos
I used to read many automobile magazines, also Popular Electronics and Popular Mechanics since the sixties.... i know those things from Rolls and Royce.
I had a beetle for 10 years long...no one have touched on it...i was the repair man.
Also i had a Dodge Charger... this one i have need some help.
Roll and Royce have told the true...also my amplifier is truly a very good unit.
Automobiles, cars was a passion to me, also my daugthers, audio electronics, tape recorders , Radio Amateur and Chocolate.
regards,
Carlos
Thank you very much for your feedback... I'm checking out right now roender's design... I'll decide which one I will build after carefull considerations. Once again, thanks...
I am not swapping you out, kicking you out, trying to be rid of you, to be free of
you.
But i am old and very experienced related kind of audiophiles.
The ones that has interest to measurements will never appreciate my "forced to work amplifiers"... made into my garage or back yard...i am not Academic, not enginneer, not a designer.
I am very skilled... 47 years doing, building amplifiers... this develop some sensors, alike dog i can sniff circuit sonics (not too much, but i can, in advance, know how something may sound just watching the schematic).... more than 4300 amplifiers already made.
When people has interest to IMD and THD, where my simulator show always good numbers (and i do not trust that good will...always showing great numbers!...good and small distortions) them i give up to use those things.. when i see someone interested in high scientific numbers.... i use to send them to the scientists alike Roender, PMA, Michael Bittner and others we have around.
I belong to the group of "tweak and listen."..and into this work i think is am very good..hard work...burning fingers..forcing things to work you know.
regards
Carlos
you.
But i am old and very experienced related kind of audiophiles.
The ones that has interest to measurements will never appreciate my "forced to work amplifiers"... made into my garage or back yard...i am not Academic, not enginneer, not a designer.
I am very skilled... 47 years doing, building amplifiers... this develop some sensors, alike dog i can sniff circuit sonics (not too much, but i can, in advance, know how something may sound just watching the schematic).... more than 4300 amplifiers already made.
When people has interest to IMD and THD, where my simulator show always good numbers (and i do not trust that good will...always showing great numbers!...good and small distortions) them i give up to use those things.. when i see someone interested in high scientific numbers.... i use to send them to the scientists alike Roender, PMA, Michael Bittner and others we have around.
I belong to the group of "tweak and listen."..and into this work i think is am very good..hard work...burning fingers..forcing things to work you know.
regards
Carlos
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