Help with possible broken EHX 12AY7

[Nick Sevilla]

Ok I found a TRS - XLR cable lying around with a gold pin on the 1/4 side, plus I changed the 12AX7 tube out and opened it up and looked around to see if anything was loose. Nothing seemed loose and the boards looked good no burn marks. I can now at least hear the mic I have plugged in and theres no hiss but there is a terribly loud hum. I dont think the hum issue was ever resolved in the other thread besides giving it a good whack. You had an issue with yours having a very loud hum at first to didnt you what did you do to yours to get rid of the hum?

Send it in to EHX. This hum, it sounds like a bad omen. They will fix it for you.

Cheers

[jckinnick]

Ok I found a TRS - XLR cable lying around with a gold pin on the 1/4 side, plus I changed the 12AX7 tube out and opened it up and looked around to see if anything was loose. Nothing seemed loose and the boards looked good no burn marks. I can now at least hear the mic I have plugged in and theres no hiss but there is a terribly loud hum. I dont think the hum issue was ever resolved in the other thread besides giving it a good whack. You had an issue with yours having a very loud hum at first to didnt you what did you do to yours to get rid of the hum?

Cool. I'm glad you were able to at least week out the hiss. As a last ditch effort, have you tried plugging the AC adapter into a different outlet? Or even flipping it the other way around in the same outlet? I have read that sometimes flipping the polarity of AC power cables and at times eliminate or reduce hum. I'll see if I can find the pages I read that on and post them up.

I don't recall mine ever having a hum issue. The main problems mine had from the start were the Power LED situation mentioned above, and very low gain. All of this ended up being related to the tube being loose and not properly seated. The tube was loose and once I seated it properly, the Power LED would stay on when Phantom was applied, the gain improved improved, and the pre opened up noticeably.

-Darrill

Ill try plugging it up in a different outlet I even got one of those Humx things I could put before it to try and cut down the hum.

I bought this thing on Ebay would EHX still fix it for me? Do I need to call before I send it to them?

[KennyLusk]

email customerservice@ehx.com before you mail it. Someone there will tell you what to do.

[trodden]

Ok I found a TRS - XLR cable lying around with a gold pin on the 1/4 side, plus I changed the 12AX7 tube out and opened it up and looked around to see if anything was loose. Nothing seemed loose and the boards looked good no burn marks. I can now at least hear the mic I have plugged in and theres no hiss but there is a terribly loud hum. I dont think the hum issue was ever resolved in the other thread besides giving it a good whack. You had an issue with yours having a very loud hum at first to didnt you what did you do to yours to get rid of the hum?

i had 2 of these, kept 1 (selling it). the first 1 i bought works flawlessly, i understand it's one of the first units..no hums no nothing. second unit was very recent (in relation to the other) and it hummed no matter what - different valves, different cabling, different PSU (EH one), different room, etc.

nothing worked. i kept the good one but i'm also selling that one as well. sorry bout the shameless plug. if anyone's interested, let me know.

*note to self. Don't buy (broken) gear from you know who*

[jckinnick]

Ok I found a TRS - XLR cable lying around with a gold pin on the 1/4 side, plus I changed the 12AX7 tube out and opened it up and looked around to see if anything was loose. Nothing seemed loose and the boards looked good no burn marks. I can now at least hear the mic I have plugged in and theres no hiss but there is a terribly loud hum. I dont think the hum issue was ever resolved in the other thread besides giving it a good whack. You had an issue with yours having a very loud hum at first to didnt you what did you do to yours to get rid of the hum?

i had 2 of these, kept 1 (selling it). the first 1 i bought works flawlessly, i understand it's one of the first units..no hums no nothing. second unit was very recent (in relation to the other) and it hummed no matter what - different valves, different cabling, different PSU (EH one), different room, etc.

nothing worked. i kept the good one but i'm also selling that one as well. sorry bout the shameless plug. if anyone's interested, let me know.

*note to self. Don't buy (broken) gear from you know who*

Thats probably how I ended up with this piece of junk.

[jckinnick]

Ok I found a TRS - XLR cable lying around with a gold pin on the 1/4 side, plus I changed the 12AX7 tube out and opened it up and looked around to see if anything was loose. Nothing seemed loose and the boards looked good no burn marks. I can now at least hear the mic I have plugged in and theres no hiss but there is a terribly loud hum. I dont think the hum issue was ever resolved in the other thread besides giving it a good whack. You had an issue with yours having a very loud hum at first to didnt you what did you do to yours to get rid of the hum?

Cool. I'm glad you were able to at least week out the hiss. As a last ditch effort, have you tried plugging the AC adapter into a different outlet? Or even flipping it the other way around in the same outlet? I have read that sometimes flipping the polarity of AC power cables and at times eliminate or reduce hum. I'll see if I can find the pages I read that on and post them up.

I don't recall mine ever having a hum issue. The main problems mine had from the start were the Power LED situation mentioned above, and very low gain. All of this ended up being related to the tube being loose and not properly seated. The tube was loose and once I seated it properly, the Power LED would stay on when Phantom was applied, the gain improved improved, and the pre opened up noticeably.

-Darrill

Ill try plugging it up in a different outlet I even got one of those Humx things I could put before it to try and cut down the hum.

I bought this thing on Ebay would EHX still fix it for me? Do I need to call before I send it to them?

I tried the little Ebtech Hum X on it and it still didnt get rid of the hum. Do you think the hum could be in the power pack or a ground loop?

[jckinnick]

Just got a response email looks like there going to fix it for me.

[nlmd311]

Just got a response email looks like there going to fix it for me.

Awesome!

Oh, and just saw your last post...I have no idea if the hum could be in the powerpack or ground loop, I was just throwing ideas out there.

Hope it comes back quickly, and quiet!

Let us know what's up once you get it back. It's always good to hear the follow ups on things like this.

-Darrill

[jckinnick]

Just got a response email looks like there going to fix it for me.

Awesome!

Oh, and just saw your last post...I have no idea if the hum could be in the powerpack or ground loop, I was just throwing ideas out there.

Hope it comes back quickly, and quiet!

Let us know what's up once you get it back. It's always good to hear the follow ups on things like this.

-Darrill

Just a follow up they sent it back to me within a week. It still has a slight hum but nowhere near what it was, they even gave me an extra tube. There is also a very slight tube crackling. Ive found that using the buffered out works the quietest for me.

[KennyLusk]

The buffered output bypasses all the circuitry in the box though - it's a totally unaffected signal, so you may as well not even have the box in your signal path.

[jckinnick]

Are you sure. If I hook it up any other way it still has an awful hum.

[jckinnick]

The buffered output bypasses all the circuitry in the box though - it's a totally unaffected signal, so you may as well not even have the box in your signal path.

Youre thinking of bypassing, buffered and bypassing are two different things. The gain knobs shouldnt work if it was bypassing.

[Nick Sevilla]

Are you sure. If I hook it up any other way it still has an awful hum.

Maybe it is NOt your EHX preamp doing the humming?

How are you plugging in?

Have you used different cables / known good cables?

Is the source hum-free when plugged into another preamp?

[jckinnick]

Are you sure. If I hook it up any other way it still has an awful hum.

Maybe it is NOt your EHX preamp doing the humming?

How are you plugging in?

Have you used different cables / known good cables?

Is the source hum-free when plugged into another preamp?

"If you haven't already, try running XLR out of the 12AY7 to TRS into the DP01"

Never mind I was hooking it up the opposite of what nlmd311 suggested earlier. Now it sounds great still not sure if the buffering is a true bypass or not though.

[jckinnick]

Are you sure. If I hook it up any other way it still has an awful hum.

Maybe it is NOt your EHX preamp doing the humming?

How are you plugging in?

Have you used different cables / known good cables?

Is the source hum-free when plugged into another preamp?

"If you haven't already, try running XLR out of the 12AY7 to TRS into the DP01"

Never mind I was hooking it up the opposite of what nlmd311 suggested earlier. Now it sounds great still not sure if the buffering is a true bypass or not though.

I bought me some longer cables so I could run things accordingly instead of just having jumpers strung everywhere and now it seems the hum is back.