The Asus card was swapped out with a Creative card and all noise issues were eliminated. Is it the card or slot this is to be investigated.
Yes, Power supply unit MUST! be earth grounded, along with all other grounds that return to the PSU.
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hi,
i have bought also the NAP200 board, and i have notice that there is some harmonic distortion hear by electronic music.
even when the volume is low the distortion will be heard
i have adjust the trim to 4,5 mv but still the same problem
i use 2 x 30 volt transformers instead of 2 x 28 volt
does anyone has the same problem?
thx
i have bought also the NAP200 board, and i have notice that there is some harmonic distortion hear by electronic music.
even when the volume is low the distortion will be heard
i have adjust the trim to 4,5 mv but still the same problem
i use 2 x 30 volt transformers instead of 2 x 28 volt
does anyone has the same problem?
thx
I can't say what could be wrong since you only say you bought the NAP200 board. If that means you bought a kit, complete with specified parts, fine. If you bought the PCB and used your own source components, you could perhaps have poorly copied parts that are giving problems. It could even be wrong pinouts on the TO92 parts, which I find is normal on Chinese generic transistors marked as 2N5551/2N5401 for example.
You need to check all possibilities there, if the parts are not the same as specified on the overlay or are really poor copies or re-marked substitutes of the specified parts. That goes particularly for the VAS transistors, ZTX653/753 if you had to use substitutes. They are very different looking to the TO92 package, so also very hard to copy.
The VAS transistors will probably overheat if you use 43V supply rails. If your local supply voltage is low, you may be OK but 40V rails is the specified maximum - meaning 2x 27-28V transformer secondaries. It also means you may also have to check and adjust bias currents in the input and VAS stages too, though I don't think high supply voltages alone would cause distortion.
Even in this climate, 43V rails will make most NAP amplifiers run too hot in summer. The case should not be ventilated though, or it won't warm up to the correct operating bias level within 30 mins or so. Notice that the Vbe multiplier transistor is nowhere near the output stage so it will take a long time for temperatures to become stable before you can set a correct, steady 30 mA bias for best compromise sound quality.
You need to check all possibilities there, if the parts are not the same as specified on the overlay or are really poor copies or re-marked substitutes of the specified parts. That goes particularly for the VAS transistors, ZTX653/753 if you had to use substitutes. They are very different looking to the TO92 package, so also very hard to copy.
The VAS transistors will probably overheat if you use 43V supply rails. If your local supply voltage is low, you may be OK but 40V rails is the specified maximum - meaning 2x 27-28V transformer secondaries. It also means you may also have to check and adjust bias currents in the input and VAS stages too, though I don't think high supply voltages alone would cause distortion.
Even in this climate, 43V rails will make most NAP amplifiers run too hot in summer. The case should not be ventilated though, or it won't warm up to the correct operating bias level within 30 mins or so. Notice that the Vbe multiplier transistor is nowhere near the output stage so it will take a long time for temperatures to become stable before you can set a correct, steady 30 mA bias for best compromise sound quality.
The amplifier sounds ok but only with special electric sound like yellow you hear some distortion. If you play other music there is now pRobles.
The distortion you hear could be due a number of sources but obviously, Yellow has nothing to do with it - perhaps it's their typical pulsating high level/ bass program. It isn't feasible to reduce the voltage to the front end on the PCB, so unless I had a dual bench power supply, I would power up with a Variac in the mains supply or even a couple of diode strings, one in each DC rail before the smoothing caps, to reduce the DC supply and see if that had any significant effect when <40V supplies are used. That means quite a few diodes or bridges but they don't need to more than ~2A rated for testing.
Even so, if you read comments on this model in the big NAP140 Ebay kit thread, not all substitutes used in this kit are matched or selected Hfe range as I believe some should be.
Edit: I should have seen your comment that you get distortion even at low volume. It suggests that overload of your preamp, before the volume control, is where the problem lies.
Even so, if you read comments on this model in the big NAP140 Ebay kit thread, not all substitutes used in this kit are matched or selected Hfe range as I believe some should be.
Edit: I should have seen your comment that you get distortion even at low volume. It suggests that overload of your preamp, before the volume control, is where the problem lies.
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Hi Ian,
But u have try several preamp if I lower the offset to 1.5 mV then the distortion is almost gone but still heard.
I will try first the voltage of the transformers from 30 to 25 volt.
But u have try several preamp if I lower the offset to 1.5 mV then the distortion is almost gone but still heard.
I will try first the voltage of the transformers from 30 to 25 volt.
Offset voltage is unlikely to have any affect on audio through speakers. !.5 mV or 15 or even 30 mV will not alter what you hear until it approaches 100mV or more and begins to displace the speaker cones away from the normal resting position and raise the coil temperature.
The next point is about distortion. What do you think harmonic distortion is? I can't hear it as an effect, only feel an overall sweetness, warmth, coldness or "colour" of the tone and even that is difficult to identify unless you have a pure sinewave tone to compare through a reference, low distortion amplifier.
Perhaps what you hear is not harmonic distortion but clipping distortion, when the signal amplitude exceeds the maximum that can be passed through the device. That is clearly heard as harshness or a vibrating, rapid switching effect on bass. The effect heard is dependent on the frequency but in the extreme, it could be described as "comby", like when you use a comb and piece of paper to make a crude harmonica. Unfortunately, it is not easy to identify what is happening by description, until you see it on an oscilloscope.
Since bass is the loudest part of modern popular music, it is bass distortion that you will probably recognize first. If you say you only hear distortion on certain recordings that possibly have a lot of bass or perhaps are recorded at higher levels that others, this would support clipping or related faults. If there is a component or assembly fault that is causing this, it may sound different on either channel. Is that the case?
The next point is about distortion. What do you think harmonic distortion is? I can't hear it as an effect, only feel an overall sweetness, warmth, coldness or "colour" of the tone and even that is difficult to identify unless you have a pure sinewave tone to compare through a reference, low distortion amplifier.
Perhaps what you hear is not harmonic distortion but clipping distortion, when the signal amplitude exceeds the maximum that can be passed through the device. That is clearly heard as harshness or a vibrating, rapid switching effect on bass. The effect heard is dependent on the frequency but in the extreme, it could be described as "comby", like when you use a comb and piece of paper to make a crude harmonica. Unfortunately, it is not easy to identify what is happening by description, until you see it on an oscilloscope.
Since bass is the loudest part of modern popular music, it is bass distortion that you will probably recognize first. If you say you only hear distortion on certain recordings that possibly have a lot of bass or perhaps are recorded at higher levels that others, this would support clipping or related faults. If there is a component or assembly fault that is causing this, it may sound different on either channel. Is that the case?
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You can surely compare 2 channels of an amplifier with an identical signal though.
You can also download free tones and tone generator software for testing.
You can also download free tones and tone generator software for testing.
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What components i should check for increased dc output? I've built NAP140 clone on my own etched pcb's, q1,q2 with 10% hfe imbalance and everything was ok, dc output under 10mv.
After a while a started to play a little with 620r resistor trying to increase a little the current thru LTP up to 2mA. When i decided to reverse back to 1mA noticed my dc out increased to 0.9-1V. Tried to exchange q1 and q2 but still my dc out is almost 1v. What else to check, what could lead to this dc output increase?
Thanks!
Adrian
After a while a started to play a little with 620r resistor trying to increase a little the current thru LTP up to 2mA. When i decided to reverse back to 1mA noticed my dc out increased to 0.9-1V. Tried to exchange q1 and q2 but still my dc out is almost 1v. What else to check, what could lead to this dc output increase?
Thanks!
Adrian
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That's a large increase. It suggests that the parts you refitted to return to 1.5 mA, may now be wrong value, damaged or there is short or break in a trace that you haven't noticed. Check the collector resistor of Q1 which I assume is the same as TR1 on the Naim schematic(s) you find posted here.
Do you have the other channel complete for comparison?
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That's good news. How did you identify this part as bad? Did you swap transistors between channels or just try some spare parts?
Just today still distortion, with several preamps and source.
it seems that this is an fault in the design.
you hear this only with music with lot of impuls
sound like grh grh grh
don't know were to start
it seems that this is an fault in the design.
you hear this only with music with lot of impuls
sound like grh grh grh
don't know were to start
First of all, download these music files:
https://www.upload.ee/files/6540835/03_breaking_in.mp3.html
https://www.upload.ee/files/6540837/05_draynor_market.mp3.html
And for pianos, browse this youtube music video:
https://www.youtube.com/watch?v=qycqF1CWcXg
I did want to write a long time here but had no time for this, sorry.
About your problem. You might have it on input section were the LPT transistors are not matched correctly. Make sure they are same brand and same HFE
Second, a very big distortion will come from two upper songs... if your Drivers are not correctly biased.
Make sure that Your MJE's aren't bad. Theyr voltage drop from base to emitter and collector should be around 660mV.
Example:
Having TIP41C/TIP42C as drivers, i found that if TIP42C is about 645mV(from emitter to base, collector to base) and tip41C is ~580mV (from base to emitter and base to collector). By installing them into naim circuit, distortion will occour. The current draw will increase when drums hit on the two songs...
Yep, it is like electronic distortion... its not disturbing to the Ears... its funny and silly😀 Like amplifier is choking on itself.
Make sure Your drivers are not so different from each-other.
By, installing correct value transistors in Driver position... and having very high HFE input transistors that are SAME GAIN, you will get hell of a drive out of this amp, a concert type feeling...
Very fast transistors on the output will eat up the bass a little, amplifier becomes more controlled.
I tried 2n3055 MEV and gentlemans, the drive from low to mid range frequency was indescribable, the "Clutch albums"... it was something big, i felt all this vibration and screaming in my chest.
Remember... ZTX753 paired with 653, 47uF LOSSY tantalum on feedback and bypass position transfers this amplifier !!!!
Also, MPSA06 is important which has its impact on softer highs and more mid-freq. drive.
And, Drivers are both good... TIP41C/TIP42C more vibration on bass tones... bass gitarre and so on.
MJE243/253 will make upper frequency's more natural, vibrating.
And ofcourse dont get inputs wrong..
BEST comes from BC550B PH03 transistors.. HFE500+
I have BC550C PH68, PH86, they are about same HFE as BC550B but do NOT SOUND AT ALL.
Also, everything else in this position is crap.
The first two mp3's are not some kind of computer created BS, it has been recorded live in a big concert room with orchestra.
All this listening has been made with Creative Soundblaster RX soundcard...
As someone said here... naim is a very narrow design.. with little margin in mind... if you get it wrong... you wont get that big feel of a music RHYTM, Separation and drive power.
For example... if naim compared to H-140 clone on ebay... then yes... H-140 is OK in small room, easier to listen..but if one moves to a bigger room with 8inch speakers, guess who is the winner.
EDIT: i have been in many places lately... Lots of different speaker enclosure types were listened to.
this type with 15" inside... 96dB sensitivity only for speaker element... now imagine how much gain was added by enclosure alone 😀
https://www.upload.ee/image/6541056/ed2.jpg
This karlson setup could be drived from a 5V USB amplifier to a pretty loud levels (YYY)
And BG20 in this type of horn enclosure:
https://www.upload.ee/image/6541057/4a8a208ec8a6f85e20ba07ae288c516d.jpg
With horn types, it felt like bass came 1 hour later 😀 Good with slow type music, bad with electronics.
But, none of the amplifiers (crest audio PA, CLASS D philips, SE tube amplifier) beat original naim in terms of drive power 😀
https://www.upload.ee/files/6540835/03_breaking_in.mp3.html
https://www.upload.ee/files/6540837/05_draynor_market.mp3.html
And for pianos, browse this youtube music video:
https://www.youtube.com/watch?v=qycqF1CWcXg
I did want to write a long time here but had no time for this, sorry.
About your problem. You might have it on input section were the LPT transistors are not matched correctly. Make sure they are same brand and same HFE
Second, a very big distortion will come from two upper songs... if your Drivers are not correctly biased.
Make sure that Your MJE's aren't bad. Theyr voltage drop from base to emitter and collector should be around 660mV.
Example:
Having TIP41C/TIP42C as drivers, i found that if TIP42C is about 645mV(from emitter to base, collector to base) and tip41C is ~580mV (from base to emitter and base to collector). By installing them into naim circuit, distortion will occour. The current draw will increase when drums hit on the two songs...
Yep, it is like electronic distortion... its not disturbing to the Ears... its funny and silly😀 Like amplifier is choking on itself.
Make sure Your drivers are not so different from each-other.
By, installing correct value transistors in Driver position... and having very high HFE input transistors that are SAME GAIN, you will get hell of a drive out of this amp, a concert type feeling...
Very fast transistors on the output will eat up the bass a little, amplifier becomes more controlled.
I tried 2n3055 MEV and gentlemans, the drive from low to mid range frequency was indescribable, the "Clutch albums"... it was something big, i felt all this vibration and screaming in my chest.
Remember... ZTX753 paired with 653, 47uF LOSSY tantalum on feedback and bypass position transfers this amplifier !!!!
Also, MPSA06 is important which has its impact on softer highs and more mid-freq. drive.
And, Drivers are both good... TIP41C/TIP42C more vibration on bass tones... bass gitarre and so on.
MJE243/253 will make upper frequency's more natural, vibrating.
And ofcourse dont get inputs wrong..
BEST comes from BC550B PH03 transistors.. HFE500+
I have BC550C PH68, PH86, they are about same HFE as BC550B but do NOT SOUND AT ALL.
Also, everything else in this position is crap.
The first two mp3's are not some kind of computer created BS, it has been recorded live in a big concert room with orchestra.
All this listening has been made with Creative Soundblaster RX soundcard...
As someone said here... naim is a very narrow design.. with little margin in mind... if you get it wrong... you wont get that big feel of a music RHYTM, Separation and drive power.
For example... if naim compared to H-140 clone on ebay... then yes... H-140 is OK in small room, easier to listen..but if one moves to a bigger room with 8inch speakers, guess who is the winner.
EDIT: i have been in many places lately... Lots of different speaker enclosure types were listened to.
this type with 15" inside... 96dB sensitivity only for speaker element... now imagine how much gain was added by enclosure alone 😀
https://www.upload.ee/image/6541056/ed2.jpg
This karlson setup could be drived from a 5V USB amplifier to a pretty loud levels (YYY)
And BG20 in this type of horn enclosure:
https://www.upload.ee/image/6541057/4a8a208ec8a6f85e20ba07ae288c516d.jpg
With horn types, it felt like bass came 1 hour later 😀 Good with slow type music, bad with electronics.
But, none of the amplifiers (crest audio PA, CLASS D philips, SE tube amplifier) beat original naim in terms of drive power 😀
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Rensli,
thanks for the info, my NAP 200 is complete assembly
the voltage i use are two transformers 2 x 25 volt
i will try this all and see what happen.
thx
thanks for the info, my NAP 200 is complete assembly
the voltage i use are two transformers 2 x 25 volt
i will try this all and see what happen.
thx
And do not even think about creating you own ideas to the amplifier...
All this BS happening on the internet to make naim amplifier better has been a big TROLL and FAIL.
Just search for the correctest bias and the values closest to the naim and its bias points... you will end up with a rock-solid power.
If your speakers are 8inch atleast... and room is around 20m2 big... you should hear no distortion of any-kind with the two uploaded mp3.s. Drums and bass should play deep, long with good feel.
All this BS happening on the internet to make naim amplifier better has been a big TROLL and FAIL.
Just search for the correctest bias and the values closest to the naim and its bias points... you will end up with a rock-solid power.
If your speakers are 8inch atleast... and room is around 20m2 big... you should hear no distortion of any-kind with the two uploaded mp3.s. Drums and bass should play deep, long with good feel.
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