ACMP 81 For Vocals

[hicksjd9]

How are these for vocals? I'm getting ready to buy one and was wondering how they would do (with eq disengaged) with dynamic mics such as a shure sm57, sm58, or a sm7b. I want a pre that makes those mics come to life, is the acmp 81 that pre? Also, once the eq hum/buzz issues are fixed, do you think it will improve even more as a mic pre? Should I just wait and get a FMR RNP?

[dgatwood]

I think with the right fixes for the hum problems, it has the potential to be a nice piece of hardware. Even with the hum only about 90% fixed in mine, I can hear its true colors shining through.

[hicksjd9]

Thanks for the quick reply! I wonder how it would compare to the real thing? Apparently the neve 1081 and the sm7b are supposed to be an AMAZING combination. Has anyone ever worked with a real neve? If you have do you think this compares or even comes close to comparing?

Also, how sure do you feel that a fix will materialize for these things? Anyone see the possibility of a fix kit appearing in the future or detailed fix instructions?

[cnix]

I do not have the ACMP-81, but do have the ACMP-73 and 84 and prefer them to the RNP. There will be a fix, but no idea on the time frame, and for a non electrical person like me, will probably have someone else fix the eq section on my 73, my 84 has no issues. I am very impressed with the tone shaping I can achieve on my 84 with the eq, comparable to much more expensive outboard eq's.

[antichef]

After the hum fix on the ACMP-81, it's kick ass -- very full sound. It has a high impedance input option for mics, and you want to use that with [probably everything, but definitely] dynamics.

I've been plugging in a TAB-Funkenwerk-transformer modded SM57 into mine, and it sounds really good -- very organic/analog and without nasty artifacts and over/undertones. I can use the EQ all I want, pretty much, because I did the transistor swap (and it worked for me). I was messing with that last night, I was thinking I "improved" the sound -- I was just talking through it, but haven't really scratched the surface of what the EQ can do, because of all the options. But I think I'll keep using it as I have been -- generally using the EQ as a post-tracking outboard effect to enhance mixes or particular tracks after the fact. Back to the philosophy of tracking as dry as possible.

My guess is that over the next year or so, as all the hand-wringing works itself out and everyone gets their units fixed or sold to someone who fixes them, we'll collectively grow to appreciate these preamps. I'm already *very* glad I signed up.

(disclaimer -- I've never seen or worked with a RNP)

[dgatwood]

Originally Posted by cnix

I do not have the ACMP-81, but do have the ACMP-73 and 84 and prefer them to the RNP. There will be a fix, but no idea on the time frame, and for a non electrical person like me, will probably have someone else fix the eq section on my 73, my 84 has no issues. I am very impressed with the tone shaping I can achieve on my 84 with the eq, comparable to much more expensive outboard eq's.

What's wrong with the EQ section on your 73? No sound? Hum? Swishing noises?

Both of mine are fine, and given that both of my 81s hum like a cheap fluorescent lamp ballast, I figure that means the problem with your 73 is a fluke rather than a design problem, but that's more a gut feeling than anything else.

I'm guessing you only have one 73? If you have a second one that is working, it would be pretty easy to figure out which board is bad---swap one board at a time into a working one. The only ones that could be involved are the four EQ boards (the boards towards the front of the unit, but not the one on the left).

[cnix]

Originally Posted by dgatwood

What's wrong with the EQ section on your 73? No sound? Hum? Swishing noises?

Both of mine are fine, and given that both of my 81s hum like a cheap fluorescent lamp ballast, I figure that means the problem with your 73 is a fluke rather than a design problem, but that's more a gut feeling than anything else.

I'm guessing you only have one 73? If you have a second one that is working, it would be pretty easy to figure out which board is bad---swap one board at a time into a working one. The only ones that could be involved are the four EQ boards (the boards towards the front of the unit, but not the one on the left).

The pre on my ACMP-73 is quiet, but when I engage the eq, there is just a slight bit of hum, very subtle, but it is there. I have done nothing as far as a fix, and I'm not electrically minded enough to know what to do. I figure when all is said and done, someone will post a picture or 2 with instructions. I could try and rotate the toroid, but I do not even know what it is!!! LOL So, my 84 is great, pre and eq, and in the short term, will run things needing eq through that unit.

Charlie

[dgatwood]

Originally Posted by cnix

The pre on my ACMP-73 is quiet, but when I engage the eq, there is just a slight bit of hum, very subtle, but it is there. I have done nothing as far as a fix, and I'm not electrically minded enough to know what to do. I figure when all is said and done, someone will post a picture or 2 with instructions. I could try and rotate the toroid, but I do not even know what it is!!! LOL So, my 84 is great, pre and eq, and in the short term, will run things needing eq through that unit.

Charlie

The toroid is that giant transformer in the upper right corner of the case. In theory, rotating it should make no difference; emissions from a toroidal transformer should be almost identical (and relatively small) in every direction. That's the point of using that style of transformer. Unfortunately, these are far from perfectly wound. Sounds like perhaps yours sucks. Or it could be something else.

Okay, if it is very subtle, then I suspect you're just getting a little leakage into the inductor. I'm assuming that you don't get any scratchy popping noises when you turn the pots on the fronts of the EQ boards, right?

[cnix]

You are correct Mr. dgatwood, no other issues. It seems leakage makes sense, just not a major issue at the moment for me.

[dgatwood]

In that case, try turning the power transformer. It probably got mis-wound slightly on one side.