[cmac]

Do you have another op-amp you can swap in to rule out a bad op-amp?

Alright, I finally got swapping a BA512 op amp from one of my working Copper Pres. It worked! Perhaps it got fried when the capacitors C505-506 blew? Anyway, that is definitely the issue, I tested the input output knobs and Pad switch. The preamp worked perfectly with the new Op Amp. I am to assume the easiest solution is to order a new one from hairball? They are so small I imagine it would be difficult, if not impossible, to troubleshoot? Glad its figured out! As always, thanks for the help.

Clinton

[Hairball Audio]

Alright, I finally got swapping a BA512 op amp from one of my working Copper Pres. It worked! Perhaps it got fried when the capacitors C505-506 blew? Anyway, that is definitely the issue, I tested the input output knobs and Pad switch. The preamp worked perfectly with the new Op Amp. I am to assume the easiest solution is to order a new one from hairball? They are so small I imagine it would be difficult, if not impossible, to troubleshoot? Glad its figured out! As always, thanks for the help.

Clinton

Not impossible, but I find it easier just to get a new one.

Mike

[EmoRiot]

Hey there Hairball. I started my build tonight and everything was going swimmingly stuffing my PCB with resistors until I got to the last three. Shown below...



But the color bands on the resistors I have indicate, if I'm reading them correctly, that I have two 2M resistors and one 1M resistor - not 200k and 100k. I've got a picture of my resistors below as they were in my kit. Do I have the wrong resistors or am I reading these bands wrong?

[EmoRiot]

Aha! I figured it out.

The orange band looked yellow to me. But if I recognize it at orange then the values make sense and I'm off and on my way with diodes and transistors.

[Fuzz Face]

Aha! I figured it out.

The orange band looked yellow to me. But if I recognize it at orange then the values make sense and I'm off and on my way with diodes and transistors.

Do you have a DMM? As stated in the build guide, you should double check resistors by measuring them. Then there’s no question

[EmoRiot]

Do you have a DMM? As stated in the build guide, you should double check resistors by measuring them. Then there’s no question

Yeah I had been testing them all night but the readings on those three were a little weird - but only when I was unsure of the bands. Once I set my DMM correctly for the expected resistance it all read as expected. Thanks!

[iantaylorsutton]

Just finished my 2nd Copper mic pre kit (built the first one about 8 mos ago). Anyway, I've noticed that the first one I built has a significantly reduced output compared to the new one. Any thoughts on what might be causing this? I've included a picture showing how vastly different they are from each other; as shown both preamps are producing the same amount of signal from the same microphone with the same cable.

Thank you!

Ian

[Hairball Audio]

Swap the op-amps, see if the issue follows the op-amp.

Just finished my 2nd Copper mic pre kit (built the first one about 8 mos ago). Anyway, I've noticed that the first one I built has a significantly reduced output compared to the new one. Any thoughts on what might be causing this? I've included a picture showing how vastly different they are from each other; as shown both preamps are producing the same amount of signal from the same microphone with the same cable.

Thank you!

Ian

[iantaylorsutton]

Swap the op-amps, see if the issue follows the op-amp.

Thanks for the prompt reply. Good news. It turns out i'm just an idiot! I failed to take into consideration that the louder of the two preamps was also hitting my FET Rack before hitting my converters, and even in "bypass" mode and at unity gain was still bumping up the signal a few db.

Thanks again for your help!

Ian

[Hairball Audio]

Thanks for the prompt reply. Good news. It turns out i'm just an idiot! I failed to take into consideration that the louder of the two preamps was also hitting my FET Rack before hitting my converters, and even in "bypass" mode and at unity gain was still bumping up the signal a few db.

Thanks again for your help!

Ian

Nice!