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Post by keymod on Jan 3, 2024 16:56:20 GMT -6
Are ECC81 , ECC82 and ECC83 interchangable in a microphone preamp situation? What other common designations refer to these tubes?
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Post by audiospecific on Jan 3, 2024 22:35:30 GMT -6
Are ECC81 , ECC82 and ECC83 interchangable in a microphone preamp situation? What other common designations refer to these tubes?
Depends on the circuit but Ecc82 (12AU7) is more of driver tube than a small gain tube. Ecc83 is the high gain AKA 12AX7. Ecc81(12AT7) is a medium gain tube.
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Post by keymod on Jan 4, 2024 3:47:32 GMT -6
Thank you. This circuit is a Sound Skulptor MP66, and uses the ECC81 on input side and ECC82 on output. The pre has started to cut in/out and make crackling noises and I would like to troubleshoot further using whatever tubes I have lying around. Can I use an ECC83 in place of the ECC82?
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Post by audiospecific on Jan 4, 2024 8:49:11 GMT -6
Its probably a bad socket, cold solder joint, or the tubes not plugged in all the way. But you take a drum stick or a chop stick and slightly push on the riser board from the corners to see if there is solder joint issues (it will act up if that is the problem) and the other test is barley touch the stick to the tube if you get crazy popping noise touching the tube, change the tube socket.
Tube sockets are not expensive, just the industrial ones might be hard to get into that board, but the consumer ones are cheap:
I can tell someone who never dealt with vacuum tubes came up with that kit because there is guidelines for making tube circuits with horizontal mounting they didn't do.
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Post by audiospecific on Jan 4, 2024 9:16:56 GMT -6
Here is the assembly instructions for people to see what I'm talking about. www.soundskulptor.com/docs/mp66-assembly-guide-01.pdfAlso that tape thing with the riser board on top is no good That should be taped to the topside on the enclosure so the cover pushes down on the board holding it in place. If anything on the riser board, it should be grommet edging or stripped out 10 gauge wire jacket slotted to slip on the edge of the board. |
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Post by svart on Jan 5, 2024 7:52:32 GMT -6
Thank you. This circuit is a Sound Skulptor MP66, and uses the ECC81 on input side and ECC82 on output. The pre has started to cut in/out and make crackling noises and I would like to troubleshoot further using whatever tubes I have lying around. Can I use an ECC83 in place of the ECC82? When does the pre make the crackles? When you adjust gain, or just randomly during usage? If it's while you adjust gain, the gain pot might be tarnishing or arcing inside. If it's not during gain adjustment, I'd just wiggle the tubes around a bit and try it again and see if it's improved. If so, then the socket or tube pins might be tarnishing. And yes, you can try the ECC83 in place of the others for testing, but the difference in gain might make the unit act/sound strangely. |
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Post by svart on Jan 5, 2024 7:56:17 GMT -6
BTW I have a SoundSkulptor MP566 and I really like it. It's a bit too easy to overdrive, but it sounds cool.
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Post by keymod on Jan 5, 2024 13:41:20 GMT -6
BTW I have a SoundSkulptor MP566 and I really like it. It's a big too easy to overdrive, but it sounds cool. I built a pair of MP66 way before Sound Skulptor started doing 500 series. They are really nice pres, but went un-used for some time. Problem appeared on only one of the two, after being re-installed in the studio. I cleaned as many contacts/switches/etc as I could with De-Oxit but, unfortunately, the pots are sealed. I have replacement pots, but have been avoiding the surgery. Noises occur randomly while changing settings on switches or pots. Have tested using sine wave generator as input signal. |
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Post by audiospecific on Jan 5, 2024 15:31:55 GMT -6
BTW I have a SoundSkulptor MP566 and I really like it. It's a big too easy to overdrive, but it sounds cool. I built a pair of MP66 way before Sound Skulptor started doing 500 series. They are really nice pres, but went un-used for some time. Problem appeared on only one of the two, after being re-installed in the studio. I cleaned as many contacts/switches/etc as I could with De-Oxit but, unfortunately, the pots are sealed. I have replacement pots, but have been avoiding the surgery. Noises occur randomly while changing settings on switches or pots. Have tested using sine wave generator as input signal. Sounds like a bad tube socket. Which isn't uncommon for low end tube sockets they used. But if your tube is loose it will do this too. corroded pins do it also.
So I would swap the tubes out and see if its ok, or unplug and plug in the tubes so the pins seat in the socket.
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