Hi Som,
The temps are very good. You should force the bias on both amps to be the same on both channels.
As for the shield, it shouldnt be no more then 8bucks per shield and should look like the one from the photo bellow. Or diy yourself from a thick carbon steel (it doesnt remain magnetised).
As i see your amp can run with a higher bias.. I ended up with 1.65A bias, but not because i wanted more power but because it sounded very opened and relax. I cranked up the bias to 2A but the results was the same. I think it depends of the components, psu, tastes, etc.Try and listen and choose what you like most now. The decision is yours.
Cheers
Sergiu
The temps are very good. You should force the bias on both amps to be the same on both channels.
As for the shield, it shouldnt be no more then 8bucks per shield and should look like the one from the photo bellow. Or diy yourself from a thick carbon steel (it doesnt remain magnetised).
As i see your amp can run with a higher bias.. I ended up with 1.65A bias, but not because i wanted more power but because it sounded very opened and relax. I cranked up the bias to 2A but the results was the same. I think it depends of the components, psu, tastes, etc.Try and listen and choose what you like most now. The decision is yours.
Cheers
Sergiu
Attachments
Thanks Sergiu ! Amp bias on one channel is slightly higher compared to other -around 0.025 volts. But both of them have similar bias resistance of 35.7 Kohms . Probably I'll increase the bias resistance by 1K and check!
Regarding the toroidal Bowl, I'll check if I can get it made .. hopefully amp chassis should accommodate it.. it's already right!
Regarding the toroidal Bowl, I'll check if I can get it made .. hopefully amp chassis should accommodate it.. it's already right!
Your welcome my friend.
If i where you i would solder the outputs onto the back of those connectors because now it may not be a problem but in the future 5-10years you may get oxides on those conectors and wires and these things will transform in a source of aditionall noise and in the end they will turn into aditional resistors like the ones from your crc psu...
)
AndrewT also told you something like this if i remember well, you should try what he and i told you if you want to leave the amp closed for at least 10years.
I took some of AndrewT's advices regarding this amp and other stuff from other threads into acount into my build and found them very rewarding.
Cheers
Sergiu
Ps: if i was you i would solder all the wires.
If i where you i would solder the outputs onto the back of those connectors because now it may not be a problem but in the future 5-10years you may get oxides on those conectors and wires and these things will transform in a source of aditionall noise and in the end they will turn into aditional resistors like the ones from your crc psu...
)AndrewT also told you something like this if i remember well, you should try what he and i told you if you want to leave the amp closed for at least 10years.
I took some of AndrewT's advices regarding this amp and other stuff from other threads into acount into my build and found them very rewarding.
Cheers
Sergiu
Ps: if i was you i would solder all the wires.
Mine Amp (Jean Hiraga 30 Watt) is also now Completed. Its a Complete DIY right from the PCB's to Enclosure and Assembly. I started this Project in July 2016. & Now its completed. I had designed my own layout so that i don't have to use wires for transistor mountings. The PCB's (Amp, Protection & Cap Multi) are itched & assembled by me. Even the Enclosure design & Assembly is done by me. The Sound its like the Angels singing from Heaven!!!
I have used CM, there is a slight hissing sound in tweeters, which can be heard at distance of about 6 to 8 Inches from Tweeters, But when i think about the $$$$ spending on Huge Bank, I say to myself "I can live with this small hiss sound".
But the most important thing is Level of Satisfaction, the level of satisfaction which you get when you create a Master Piece right from the scratch is something you cannot describe just by words.
Sadik Bhatkar
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I have used CM, there is a slight hissing sound in tweeters, which can be heard at distance of about 6 to 8 Inches from Tweeters, But when i think about the $$$$ spending on Huge Bank, I say to myself "I can live with this small hiss sound".
But the most important thing is Level of Satisfaction, the level of satisfaction which you get when you create a Master Piece right from the scratch is something you cannot describe just by words.
Sadik Bhatkar
Congrats Sadik!
Love it! I was just like you when i finished mine and seen it fully assembled and listening to it.
Please tell us more. What schm are you using for the CM? What caps, components and where, what outputs are you using?
Maybe we can tell you how to improve the sound even further..
Love it! I was just like you when i finished mine and seen it fully assembled and listening to it.
Please tell us more. What schm are you using for the CM? What caps, components and where, what outputs are you using?
Maybe we can tell you how to improve the sound even further..
Sadik i forgot to tell you also to shield those nasty toroidals because they are emiting strong magnetic field..
In your case you can sandwich them to cancel the magnetic field without a shield.
Even if E+I trafos have lower emi in my case i put a carbon steel screen in front of them. Look at my pics a few pages back.
You should take into consideration that if you and Som worked so hard and long to achieve the best results possible, it is pitty to ruin things up at the finish line.
Cheers
Sergiu
In your case you can sandwich them to cancel the magnetic field without a shield.
Even if E+I trafos have lower emi in my case i put a carbon steel screen in front of them. Look at my pics a few pages back.
You should take into consideration that if you and Som worked so hard and long to achieve the best results possible, it is pitty to ruin things up at the finish line.
Cheers
Sergiu
that is one beautiful amp you've built there Sadik! a true DIY effort!
@Sergiu , if you are referring to connection on binding posts, yeah for now wires are soldered on spades which are screwed to binding post core. i would take your advice and solder them directly onto binding post after i change them. because, after i bought the current ones, i realized that the core of the binding post is made of Steel - i'll be upgrading them to Brass made posts over the weekend.
my rest of the copper wires are tinned at wherever screw down connectors are involved and same treatment with wires having ring terminals or spade connectors.
can't wait to post pictures of my amp - gotta wait till i update the above.
also, this morning - same amp had max of 0.577 bias voltage [1.74 Amp of Bias Current]. my mains voltage sees a lot of fluctuation.
@Sergiu , if you are referring to connection on binding posts, yeah for now wires are soldered on spades which are screwed to binding post core. i would take your advice and solder them directly onto binding post after i change them. because, after i bought the current ones, i realized that the core of the binding post is made of Steel - i'll be upgrading them to Brass made posts over the weekend.
my rest of the copper wires are tinned at wherever screw down connectors are involved and same treatment with wires having ring terminals or spade connectors.
can't wait to post pictures of my amp - gotta wait till i update the above.
also, this morning - same amp had max of 0.577 bias voltage [1.74 Amp of Bias Current]. my mains voltage sees a lot of fluctuation.
Congrats Sadik!
Love it! I was just like you when i finished mine and seen it fully assembled and listening to it.
Please tell us more. What schm are you using for the CM? What caps, components and where, what outputs are you using?
Maybe we can tell you how to improve the sound even further..
Hi Sergiu
You can check the Post No 1087 I have uploaded the Layout there, I have purchased the caps locally they are not a Branded one.
hi all, update regarding the bias settings, i updated the bias resistors to control the bias currents:
on channel A, i added 1K resistor taking the total bias resistor to 36.6 K Ohms.
results after powering/playning for for around 4 hours: 1.77 Amps of Bias Current at ~30VDC rail voltages[Night], temperature ~54 degree Celsius and 1.69 Amps at ~27VDC[Day] rail voltages
on channel B, i added 800 Ohms resistor [since this channel had lesser bias current] - total resistors 36.4 Ohms
result after powering/playing for around 3 hours: 1.76 Amps of Bias Current at ~30VDC rail voltages[Night], temperature ~51 degree Celsius] and 1.66 Amps at ~27VDC rail voltages[Day]
i also covered the RCA input cable inside the cabinet in techflex since it is running close to heat sinks. not sure if it's because of this or resistors : i can hear a very faint noise from the speakers at 2 inches distance which was not there earlier. this persists even if i disconnect the input to the amps. though i can't make out in normal conditions but in dead silence [around 3AM] i could hear them as i was seated very close to speakers. what could be the issue?
on channel A, i added 1K resistor taking the total bias resistor to 36.6 K Ohms.
results after powering/playning for for around 4 hours: 1.77 Amps of Bias Current at ~30VDC rail voltages[Night], temperature ~54 degree Celsius and 1.69 Amps at ~27VDC[Day] rail voltages
on channel B, i added 800 Ohms resistor [since this channel had lesser bias current] - total resistors 36.4 Ohms
result after powering/playing for around 3 hours: 1.76 Amps of Bias Current at ~30VDC rail voltages[Night], temperature ~51 degree Celsius] and 1.66 Amps at ~27VDC rail voltages[Day]
i also covered the RCA input cable inside the cabinet in techflex since it is running close to heat sinks. not sure if it's because of this or resistors : i can hear a very faint noise from the speakers at 2 inches distance which was not there earlier. this persists even if i disconnect the input to the amps. though i can't make out in normal conditions but in dead silence [around 3AM] i could hear them as i was seated very close to speakers. what could be the issue?
Last edited:
Hi Som,
Try something else (because you have too much ac diferences): adjust the bias in the day at 1.66A@27V and see how it drifts in the night. You have a 10mA in the night wich transforms into 30mA in the day. If you dont have very sensitive speakers and dont mind a small power difference that's ok, but if you have, you should put a trimpot of 10k with the wiper shorted to one of the trimspots ends in series with a 20k resistor and fine adjust the bias. Then put two,max three resistors in series to achieve the values you obtained on each channel. Now the chanels will drift the same.
As for the noise. Do you have a star ground installed in your chasis? If not, than make one. If yes use shielded mono mic cables because they are cheap, easy to find and have good shields in them.
I have a mains cable running beneath the right channel(aprox 7cm down) and even with star ground and shielded mic wires this channel was buzzing. I had to suplimenarry shield it with a grounded carbon steel wich doesnt remain magnetised and the noise was gone. Piece of cake.
Hope it helps
Cheers
Try something else (because you have too much ac diferences): adjust the bias in the day at 1.66A@27V and see how it drifts in the night. You have a 10mA in the night wich transforms into 30mA in the day. If you dont have very sensitive speakers and dont mind a small power difference that's ok, but if you have, you should put a trimpot of 10k with the wiper shorted to one of the trimspots ends in series with a 20k resistor and fine adjust the bias. Then put two,max three resistors in series to achieve the values you obtained on each channel. Now the chanels will drift the same.
As for the noise. Do you have a star ground installed in your chasis? If not, than make one. If yes use shielded mono mic cables because they are cheap, easy to find and have good shields in them.
I have a mains cable running beneath the right channel(aprox 7cm down) and even with star ground and shielded mic wires this channel was buzzing. I had to suplimenarry shield it with a grounded carbon steel wich doesnt remain magnetised and the noise was gone. Piece of cake.
Hope it helps
Cheers
thanks Sergiu,
i'll probably test with the speakers and if i can make out the difference between the channels, i'll try to fix this.
for noise, as i described it was silent before i did the resistor update and wrapping the input wire [orange] with techflex jacket [since it is very close to heat sink].
i've the star ground on capacitor copper plate- it has transformer ground, ground from the amp board, ground for the speaker protection board, ground for the speaker out and a ground wire connecting the chassis earth. i could also hear slight transformer noise for the first time yesterday [rail voltages were 31VDC] .
i'll probably test with the speakers and if i can make out the difference between the channels, i'll try to fix this.
for noise, as i described it was silent before i did the resistor update and wrapping the input wire [orange] with techflex jacket [since it is very close to heat sink].
i've the star ground on capacitor copper plate- it has transformer ground, ground from the amp board, ground for the speaker protection board, ground for the speaker out and a ground wire connecting the chassis earth. i could also hear slight transformer noise for the first time yesterday [rail voltages were 31VDC] .
hi all,
i've connected the Alpair 10.3M raw drivers for testing/burn in on both channels. i seem to have got rid of most of the noise but one issue remains. i have 2 mono blocks : channel A and channel B
1. if i play music from both the amps, i can hear a faint noise [sounds like 'krrr..] from the speakers even when the music is volume is lowest [or on mute].
2. if i switch off amp B while amp A still playing then the noise is gone completely.
3. but if i reverse this : i.e switch off amp A and amp B is playing i can still hear the noise.
4. and if i disconnect the amp A completely[remove the RCA cables] then there is no noise when amp B is playing.
above combination simplified - while input[preamp] is connected:
1. A[On] + B[On] = Noise
2. A[On] + B[Off] = Silent
3. A[Off] + B[On] = Noise
4. B[On]= Silent
i tried different sources and RCA cables/switching of input channels but above issue remains. what could be the issue? is amp B is the culprit?
i've connected the Alpair 10.3M raw drivers for testing/burn in on both channels. i seem to have got rid of most of the noise but one issue remains. i have 2 mono blocks : channel A and channel B
1. if i play music from both the amps, i can hear a faint noise [sounds like 'krrr..] from the speakers even when the music is volume is lowest [or on mute].
2. if i switch off amp B while amp A still playing then the noise is gone completely.
3. but if i reverse this : i.e switch off amp A and amp B is playing i can still hear the noise.
4. and if i disconnect the amp A completely[remove the RCA cables] then there is no noise when amp B is playing.
above combination simplified - while input[preamp] is connected:
1. A[On] + B[On] = Noise
2. A[On] + B[Off] = Silent
3. A[Off] + B[On] = Noise
4. B[On]= Silent
i tried different sources and RCA cables/switching of input channels but above issue remains. what could be the issue? is amp B is the culprit?
okay, i seem to have resolved the issue.
on Amp B:
1. i used PTFE tape to properly insulate the RCA posts to isolate it from chassis. RCA posts did come with isolating rings but looks like the sheet metal of chassis is thicker then those rings.
2. i redid the RCA wire input to amp PCB by shortening the wire and re-soldering all the joints.
3. i tightened all the ground wire terminals and nuts [star ground and protective earth]
above steps have helped me in eliminating the electrical noise in speakers completely. now the wait for speaker cabinets begins. right now raw drivers [Alpair 10.3M] have been connected to amps directly. i must say they sound clean , ofcourse with muted low notes since they are simply mounted in a hole carved in their own packaging cardboard box.
amps are still playing without their top plate as i'm monitoring bias voltage and heat sink temperatures. they seem to have settled nicely for now. the moment i get the speaker cabinets made my stereo set-up would be complete!
on Amp B:
1. i used PTFE tape to properly insulate the RCA posts to isolate it from chassis. RCA posts did come with isolating rings but looks like the sheet metal of chassis is thicker then those rings.
2. i redid the RCA wire input to amp PCB by shortening the wire and re-soldering all the joints.
3. i tightened all the ground wire terminals and nuts [star ground and protective earth]
above steps have helped me in eliminating the electrical noise in speakers completely. now the wait for speaker cabinets begins. right now raw drivers [Alpair 10.3M] have been connected to amps directly. i must say they sound clean , ofcourse with muted low notes since they are simply mounted in a hole carved in their own packaging cardboard box.
amps are still playing without their top plate as i'm monitoring bias voltage and heat sink temperatures. they seem to have settled nicely for now. the moment i get the speaker cabinets made my stereo set-up would be complete!
Hello Albert, they are from alliexpres (https://www.aliexpress.com/w/wholesale-cover-for-toroidal-transformer.html) but i did found some of these on my local shop cheaper.
hi Sergiu, thanks! i'm waiting for the speaker cabinets to be built. for now, music sounds crystal, especially the vocals and sound of 'tabla - a percussion instrument used liberally in Indian music sounds very authentic.
Thanks, looks good. Here all the local shops seems to have disappeared.
Here in RO these shops are still a valid source.
Of course here in our country, they usually sell carbon resistors and cheap stuff, BUT if you look carefully you can find some obsolete trannies (if you know what you are looking for) , russian military class resistors, caps, trimmers, some Dales some nos russian valves. Interesting stuff... Its petty that they are extinguished one by one in your country.Sergiu
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.