Re: I wonder...
Nuuk - do not try this! Your circuit as origionally drawn should work fine - you've got a component fault or construction fault...
Correction? You've just broken his buffer!carlosfm said:
Nuuk - do not try this! Your circuit as origionally drawn should work fine - you've got a component fault or construction fault...
mhennessy,
You're right, I was just too confused and hungry.
I'm not at home, and I don't have my things here...
My OPA627 buffer is at home.
Thinking better after eating something
, it appears you have some short there, maby one of the PSU lines touching the signal...
You're right, I was just too confused and hungry.
I'm not at home, and I don't have my things here...
My OPA627 buffer is at home.
Thinking better after eating something
, it appears you have some short there, maby one of the PSU lines touching the signal...
I love hi-fi as a hobby. That's why I created Decibel Dungeon and spend so much of my time time with the soldering iron powered up. But occassionally, I do start to question if it is all worthwhile, when I seem to go around in circles for a day or two and get back to where I started!
Having checked DC on the output of the buffers and found it to be very close to zero, I decided that on Thursday morning I would start to listen to the buffers through the GCs. So I powered everything up and pressed the PLAY button on the CDP and - no sound, at least not on the left channel but a slight buzzing noise on the right. But absolutely no music.
So I had a break and then went back to check the buffers and the connections. I could find nothing wrong so after lunch, I made up a test rig of my cassette player, a 100K pot-in-a-box, my old A60 amp and an old speaker. I tried the buffers again but still no music!
I rechecked the buffers, no shorts, no bad connections so I assumed that it must be the OPA627s although they were working when I had last used them. I found an OPA604 in my parts box and put it into one of the buffers. Connected evertything up and played some music which DID come through the speaker. Eureka! Off to search for another opamp but no luck so I swapped the OPA604 into the other buffer. This time, just a buzzing noise and no music.
So I put the OPA604 back in the other buffer and tried it but there was no sound at all. I tried playing it through the other channel of the A60 but still absolutely nothing. At that stage I needed another break and later went back to look in the A60 and found a loudspeaker fuse blown, just one.
This morning I replaced the fuse. I tested the amp without the buffers and both channels were OK. I measured the buffer that had worked again. No DC on the output, and an AC signal corresponding to the music level. I connected it up and it played OK. I decided to leave that buffer alone.
I put an OPA627 in the other buffer and measured it. Fine again, zero DC and an AC signal when music was played into it. I connected it up to the amp and it played OK.
Anyway, after some advice from Pedja about moving the 6N8 cap of the filter into the GCs and trying for about 10 minutes to fit it in, I decided to give up and wait until I have built my integrated GC which will have a lot more space than my little monoblocks!
So, I started with two working buffers and three days later, an awful lot of work and one loudspeaker fuse, I have - two working buffers.
The one thing that I am a little curious about is the couple of volts that appear momentarily on the output of the buffers when they are powered up or down. It is very brief but I wondered if it could cause a problem (something caused the fuse to blow in the A60), whether it is common but other people don't mention it, or whether using a cap between the +V and -V pins on an opamp will cure it. Any comments?
Also puzzling is why removing the 56K resistor to ground on the input, and the 47uF DC blocking cap, caused the DC offset on the GCs to go from zero to 30mV on one channel and 20mV on the other. Since putting them back the offset for both amps has returned to zero.
Having checked DC on the output of the buffers and found it to be very close to zero, I decided that on Thursday morning I would start to listen to the buffers through the GCs. So I powered everything up and pressed the PLAY button on the CDP and - no sound, at least not on the left channel but a slight buzzing noise on the right. But absolutely no music.
So I had a break and then went back to check the buffers and the connections. I could find nothing wrong so after lunch, I made up a test rig of my cassette player, a 100K pot-in-a-box, my old A60 amp and an old speaker. I tried the buffers again but still no music!
I rechecked the buffers, no shorts, no bad connections so I assumed that it must be the OPA627s although they were working when I had last used them. I found an OPA604 in my parts box and put it into one of the buffers. Connected evertything up and played some music which DID come through the speaker. Eureka! Off to search for another opamp but no luck so I swapped the OPA604 into the other buffer. This time, just a buzzing noise and no music.
So I put the OPA604 back in the other buffer and tried it but there was no sound at all. I tried playing it through the other channel of the A60 but still absolutely nothing. At that stage I needed another break and later went back to look in the A60 and found a loudspeaker fuse blown, just one.
This morning I replaced the fuse. I tested the amp without the buffers and both channels were OK. I measured the buffer that had worked again. No DC on the output, and an AC signal corresponding to the music level. I connected it up and it played OK. I decided to leave that buffer alone.
I put an OPA627 in the other buffer and measured it. Fine again, zero DC and an AC signal when music was played into it. I connected it up to the amp and it played OK.
Anyway, after some advice from Pedja about moving the 6N8 cap of the filter into the GCs and trying for about 10 minutes to fit it in, I decided to give up and wait until I have built my integrated GC which will have a lot more space than my little monoblocks!
So, I started with two working buffers and three days later, an awful lot of work and one loudspeaker fuse, I have - two working buffers.
The one thing that I am a little curious about is the couple of volts that appear momentarily on the output of the buffers when they are powered up or down. It is very brief but I wondered if it could cause a problem (something caused the fuse to blow in the A60), whether it is common but other people don't mention it, or whether using a cap between the +V and -V pins on an opamp will cure it. Any comments?
Also puzzling is why removing the 56K resistor to ground on the input, and the 47uF DC blocking cap, caused the DC offset on the GCs to go from zero to 30mV on one channel and 20mV on the other. Since putting them back the offset for both amps has returned to zero.
Come on, Nuuk...
Cheer up, we like you.
Take a break on the buffers for some days (or weeks) and you'll see that the next time you'll catch on.
There's nothing special to see on TV at night.
Better fiddle with electronics.😉
Don't worry Carlos, I'm not about to jump off a rectifier bridge 😉
Having listened to my GCs in 'standard' form again last night (Cesaria Evora) my spirits are sky high again. And I have some gardening jobs to do for my mother so there will have to be a bit of a break from the soldering iron anyway.
So your TV is as bad as ours but do you have to pay one company 120UKP each year for a licence even when you hardly watch anything?
Well, I am off to look for the garden spade so think of me while you are lying in the sun playing your Walkman through that mini GC and
ing.Nuuk said:
😱 I see you have good taste.
Nuuk said:
Well, I am off to look for the garden spade so think of me while you are lying in the sun playing your Walkman through that mini GC and
Changed ideas, that GC is going to have a serious toroid, it should be arriving any day.
There's another one I finished yesterday (complete with a box) and that one will break a WORLD RECORD.
It's so small I have to use a macro lens to take a picture of it.
Photos soon.😉
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