ACM-2 + RMX1 before and after

[antichef]

I just dropped an Edcor RMX1 transformer into my brand new self-tensioned TNC ACM-2, and here are before and after samples:

http://recursor.net/ACM2-before-trans.wav

http://recursor.net/ACM2-after-trans.wav

and, just because it's right here, here's a Nady RSM-4 (not sure why, but it reminds me of the ACM-2 a little bit)
http://recursor.net/RSM-4-stock.wav

Now the many disclaimers:
1) I don't know what I'm doing and this is my first mic transformer swap
2) I'm not a very good solderer
3) I guessed at all the wiring - the old tranny had 4 wires and the RMX1 has 5
4) Untreated room, with lots of room noise (as well as kids/baby/cat nearby) -- I did manage to stop the dishwasher, but that's about it
5) I tensioned the mic ribbon myself, and may have messed it up in some subtle way (but that would be the same for both runs - I was pretty careful with the ribbon during the swap).
6) The RSM-4 was not exempt from my tensioning rampage - it was a little saggy, and I managed to tighten it up a little bit (may have messed it up, too -- you'll have to take my word that it sounds better than it did before).

I think I reversed the polarity of the ACM-2, since the mic sounded stronger in the "front" prior to the switch, and now sounds stronger in the "back" - I might switch the output wires.

The chain is:

Martin D28 -> ACM2 -> 5' cable -> Black Lion Audio modded MOTU Traveler (pre set to +30db) -> Logic Express 8 - no effects or anything.

I was as careful as I could be about mic positioning, and I left the gain the same for comparison purposes -- the RMX1 does seem like it's a little lower output than the stock xfrmr. I had tried a higher gain with the stock one, but I was clipping, so I turned it down (unexpected for a ribbon, from what I've read).

 

[Somnium7]

The one with the transformer mod sounds somewhat brighter and better defined to me. Both of em sound ok. The stock one is also pretty similar to my ACM4 but sounds a little quieter in the mids.

I sure wish somebody would do a shootout between various ribbons including a few pricey ones from AEA or Royer along with the ACMs.

 

[antichef]

The one with the transformer mod sounds somewhat brighter and better defined to me. Both of em sound ok. The stock one is also pretty similar to my ACM4 but sounds a little quieter in the mids.

I sure wish somebody would do a shootout between various ribbons including a few pricey ones from AEA or Royer along with the ACMs.

I like the modded one better, too, even if it does require a touch more gain for the same level -- it sounds clearer. The self noise isn't noticeably different to me (you'll have to trust me on that, a bit, because there's so much room noise in the recordings), and seems very low - this is something I was a little concerned about based on earlier discussions here surrounding the specified DC resistance (higher than what we wanted to see? don't remember.)

I've got one more of the transformers, and I'm trying to figure out whether to put it in the ACM-3, the RSM-4, or the ACM-4 that I have. I really like the ACM-4, and I've been using it to mic a small tube guitar amp -- sounds amazing to me.

 

[Somnium7]

Your unmodded mic sounded too dense and smeary in the lower mids and that cleaned up with the new trafo. So far with all the samples of the ACM ribbons I've heard they all have a certain sound that I can't quite put into words. You can hear it when you compare to your sample of the RSM-4, which to me seems a little more open sounding but not as warm.


I'm glad you posted this comparison because I was trying to decide if it was worth attempting the swap myself. I'm gonna give it a shot on my ACM4.

I do remember a bit about the DC resistance topic. IMO it looks as though this may only be noticeable on some really good lab equipment for most. Whatever self noise the mic has it certainly doesn't rear it's head to my ears.

I'll have to try my ACM-4 on guitars/amps soon, I'm very curious about this. So far with my vocalist I am pretty satisfied with what I hear. Her voice works really well with large diaphragm dynamics but neither of us like how it sounds on condensers. I was hoping the ribbon would be a best of both worlds scenario and so far I'm not disappointed. I'll try to record some samples of her on it soon.