Group Buy Ribbon Mic + Edcor transformer: ACM-3 + RMX1

[antichef]

I mentioned in an earlier thread that I purchased two of the Edcor ribbon mic transformers - the RMX1 - and one of them arrived dead (I put the other one in an ACM-2 and made a thread about that). I let the Edcor folks know, and they immediately shipped a replacement (*nice*!). It arrived, and I got to work on the TnC ACM-3 from the group buy. The new one works fine.

For before/after samples, I figured out a ghetto re-amping technique (which I'll describe in a thread in the guitar section), and played the same short chord progression through a small 1960's practice amp - this allowed for pretty much identical conditions for the two samples (each 24/96 wav about 6 megs):

before: http://recursor.net/reamp/ACM3-stockTranny.wav
after: http://recursor.net/reamp/ACM3-edcor.wav

(signal path: reamp signal -> ~1965 Epi 101 EL84 amp -> ACM3 -> 5' cable -> Black Lion Audio modded MOTU traveler at +20 gain -> mac/Logic Express)

in retrospect, I maybe should have tried something more subtle, but since this is my most likely application for the mic, I figured it would be a good idea. As before, the RMX1 has a lower output, but I think a better sound.

and since reamping is so darn easy, I made bunch of bonus tracks -- placement was the same or similar (3" back from the middle of the cone), depending on the shape of the mic. I left everything else the same, including the gain on the preamp. I tried picking a bunch of mics that you might use for the same application - ribbons and dynamics.

the ACM-2 with the edcor tranny: http://recursor.net/reamp/ACM2-edcor.wav
a Nady RSM4, stock: http://recursor.net/reamp/NadyRSM4.wav
the lovely and talented ACM-4, stock (for now):http://recursor.net/reamp/ACM4-stockTranny.wav
um, SM-57: http://recursor.net/reamp/sm57.wav
and therefore, the Audix I5: http://recursor.net/reamp/i5.wav
and further, the Shure Beta 57a: http://recursor.net/reamp/Beta57a.wav
and the Shure SM-7b: http://recursor.net/reamp/sm7b.wav
and an old EV RE-10: http://recursor.net/reamp/EV-RE10.wav

I've got some Lundahl transformers on the way, but I think I'm done modding that ACM-3 - I've about DIYed it to death, having soldered/unsoldered everything about 8 times. I heated up one of the XLR pins from the inside so much that it drooped down in the plastic and sticks out further than the others. I guess I could replace that whole component, but it still works for now.

 

[crazydoc]

How big is the transformer (physical dimensions)? I don't see it posted on the site. I assume it's fairly small if it fit inside the 30mm OD ACM2 tube.

Also, with the Lundahls you have coming, do you have either another ACM2 or ACM3 to put one in? It would be useful to compare the sound of the Edcor vs Lundahl, tracking them together on the same source.

 

[antichef]

I didn't measure the transformers, but they just barely fit in the ACM-2 and ACM-3 -- no padding needed to keep them in place. I had mentioned before that they don't fit in the metal chamber that holds the transformer in the ACM-4. I'm hoping the Lundahls do.

I don't have a spare ACM-2 or 3, but I plan to do something similar to what I just did, using the ACM-2. I'll use a guitar line with more dynamic range next time, and spend more time setting the levels in the re-amping rig. Listening to those samples again just now, they're a little hotter than I had planned even for this, but at least you can still hear differences.

 

[hueseph]

I don't mean to be critical but, it seemed a bit of an unfair comparison. None of the mics have the same level so you will automatically perceive them differently. I took the liberty of downloading all of the examples and I normalized them to -3dB. I know that some people look down on normalizing but in this case I think it's the only way to level the playing field without colouring the sound as might occur using a compressor.

After having done this some things stood out to me:

At first I thought the original transformer in the ACM3 sounded much better than the mod but after having normalized the files, the tonal response of the modded ACM3 was markedly better.

I tried soloing through the mics as I had them all in one session and noticed that when I played some of the mics together, they were blatantly out of phase with each other. Of course this is kind of obvious. What was nice though is that some of the phase cancellation acted quite nicely as a natural eq.

That being said, I'm not sure how you pitted these mics against each other but I'm sure you'd agree that we don't place all mics in the same position. We place mics according to how we can get the best sound out of them.

Again, I don't know how you did your comparison, I just wonder if you took these things into consideration.

I'm not even sure how old this thread is. I just happened upon it after searching info on another budget ribbon mic. If this is old hat, please forgive me for reviving the dead.

 

[antichef]

cool -- can you post the normalized files? I moved not long ago and don't have all my stuff set back up yet.

I did make an effort at optimum mic placement, except that if two mics had the same shape/form factor, I used the same position for subsequent ones that I did for the first one.

 

[hueseph]

I can and will but not right now. Maybe tomorrow. It's uh.....midnight here right now. So sleepy. So Saturday I'll post them.

 

[hueseph]

Here we go.

https://rcpt.yousendit.com/703558036/bc3defef34f164d3b31bd9fdcf61f238