[ACM investiupgradifications] All things MICROPHONE

[okgb]

yes and it looks as if this AMC one is opposite hitting the amp then the xfmr ,
so when he bypassed the amp  ,ended up with a " normal " chinese ribbon
thanks for reporting that btw

i had thought some were xfmr  , electronics , xfmr again  , anyone know ?

 

[crazydoc]

No, it looks like the mic is upside down in the picture, with the ribbon output coming from below up into the transformer, and the output from the mic headamp (which he's bypassed) going to the XLR connector.

It may sound dark because the transformer output is not matched well to a mic preamp input with some resulting freqency abberations.

 

[mushy]

I'm just finishing the first album project I've had since I've received my mics.  My assessment is this:

ACM-3

These are dark.  The top sounds rolled off and the bottom is woolly. I'm guessing there is a bump in the neighborhood of 400 Hz.  They sound good in front of a guitar amp, but honestly, I haven't actually used any of the tracks I recorded with these.  I am going to pass these off to Marik to work his magic with at some point.

ACM-70

These I like.  I would guess that giving this sized ribbon the extra 10 or so mm to play with has paid off.  They definitely aren't transparent but they are much flatter than the ACM-3's.  The hf rolloff is much more natural sounding and the lf bump seems closer to 200 Hz making it much easier to deal with.  I've used them on guitar amps and horns and I'm very pleased with the results.  Let's be clear, these ain't a pair of Coles, but they have a sound all their own and you can reap the "ribbon mic benefits" with these quite nicely.

ACM-1200

I'll break my assessment of these into two categories:  Close and far...  Very different results....

Close:  In our vocal mic shootout, the 1200 was up against a 414, an 87, a Gefell MT711s, etc and I can honestly say I couldn't hear the difference between it and the 414.  Neither of those mics was the right choice for this guy, but still, I was impressed in how well it held it's own.  That said, it's bright and I already have a 414 and don't really need any more.

Far:  As drum room mics: meh.  They worked fine, but they definitely lack depth and detail.  Because of the hf bump, the minute you start compressing them, the cymbals get pretty trashy sounding.  I found it challenging to get the snare room sound I wanted without destroying the rest of the kit.  That said, I eventually met that challenge and like the drum sound I got in the end.

I have a pair of Dale M7s on the way for these so I'm really looking forward to modding the crap out of them. I'm going to change the transformers, swap out some components, reign in the voltages and remove the CF in one of them so I can do a direct comparison.  I don't think the capsules are as bad as people say, but the sound of these mics isn't as "special" as a good tube mic should sound. Of course I payed like $100 each for these so I ain't complaining.  As a matter of fact, all things considered, I think I made out like a bandit.

Anywho, I'm posting mixes here as I finish them:

http://www.dibsreaction.com/2009/04/10/apollo-run/

If anyone wants to hear specific splits in the interest of mic research, I'd be happy to post them.

 

[clintrubber]

I'm just finishing the first album project I've had since I've received my mics.  My assessment is this:

ACM-3

These are dark.  The top sounds rolled off and the bottom is woolly. I'm guessing there is a bump in the neighborhood of 400 Hz.  They sound good in front of a guitar amp, but honestly, I haven't actually used any of the tracks I recorded with these.  I am going to pass these off to Marik to work his magic with at some point.

Curious how close you put the mic to the amp. As it happens I toyed around with these as well last week, and woolly sure being an accurate description of the results. Realizing the proximity of these mics is pretty huge (as for more ribbons) I had another testrun yesterday (see attached pic) with more distance to source and the lows were a lot more behaved.

Certainly still pretty dark, at least w.r.t. a 'normal' dynamic mic (I realize the 421 is pretty bright), but of course we'd actually be glad they sound different, in order to have the possibility for blending different tastes of sound.

You used only the ACM-3 on gtr or was it blended with another mic ?

If anyone wants to hear specific splits in the interest of mic research, I'd be happy to post them.

Would be nice. You have mentioned mics on separate tracks I assume ?

Bye,

  Peter

 

[mushy]

Curious how close you put the mic to the amp. As it happens I toyed around with these as well last week, and woolly sure being an accurate description of the results. Realizing the proximity of these mics is pretty huge (as for more ribbons) I had another testrun yesterday (see attached pic) with more distance to source and the lows were a lot more behaved.

Certainly still pretty dark, at least w.r.t. a 'normal' dynamic mic (I realize the 421 is pretty bright), but of course we'd actually be glad they sound different, in order to have the possibility for blending different tastes of sound.

You used only the ACM-3 on gtr or was it blended with another mic ?

I had it up with a 57, a TLM170 and the ACM-70 and no matter what combo I tried it with, it seemed to be the weak link.  No, I didn't give it the time I should have to make it work because the ACM-70 sounded so right I didn't bother.  Plus I didn't have an IBP and the amp was in a smallish booth so I didn't have the time or energy to start mucking with the phase concerns generated by having mics on different planes.

I wasn't up on the grill, either.  I would say it was about a foot to 18 inches away.

Would be nice. You have mentioned mics on separate tracks I assume ?

Yah.. This gets complicated, though...  My tracks are 24 bit 88.2 Khz.  Should I post clips as is or should I make LAME encoded mp3's?

 

[clintrubber]

ACM-70

These I like.  I would guess that giving this sized ribbon the extra 10 or so mm to play with has paid off.  They definitely aren't transparent but they are much flatter than the ACM-3's.  The hf rolloff is much more natural sounding and the lf bump seems closer to 200 Hz making it much easier to deal with.  I've used them on guitar amps and horns and I'm very pleased with the results.  Let's be clear, these ain't a pair of Coles, but they have a sound all their own and you can reap the "ribbon mic benefits" with these quite nicely.

I wonder which internal type these would be then... still assuming there's only three tastes (per http://recordinghacks.com/2008/11/01/chinese-ribbon-microphone-designs/ )...  it ain't no dual ribbon I understood, so then probably a second generation - “Long Ribbon / Short path” Ribbon Motor Mic ?

 

[clintrubber]

You used only the ACM-3 on gtr or was it blended with another mic ?

I had it up with a 57, a TLM170 and the ACM-70 and no matter what combo I tried it with, it seemed to be the weak link.

You didn't get bitten by the inverted polarity of the ACM-3 I assume, right ? Then again, not unlikely the ACM-70 will be wrong in that respect then as well 

I wasn't up on the grill, either.  I would say it was about a foot to 18 inches away.

Sounds identical to the distance of my second run, most 'over-proximity' seemed to be gone there.

Would be nice. You have mentioned mics on separate tracks I assume ?

Yah.. This gets complicated, though...  My tracks are 24 bit 88.2 Khz.  Should I post clips as is or should I make LAME encoded mp3's?

We might better skip this I guess, since the value of the effort will quickly be a 'FWIW' since we both have more or less identical mics but different circumstances and goals.

Bye,

  Peter

 

[mushy]

Well, here's something that might start a lively discussion... 

If you fellas hadn't noticed, what I have proposed as my ACM-1200 mod was taking a C12 style mic, putting a U47 style capsule in it (dale M7) with a C12-ish transformer (cinemag 2480) and an Elam-esque circuit. 

Disadvantages?  Advantages? 

Discuss....

 

[rodabod]

I've tried that. I wasn't massively impressed, but you may like it. I found the amp wasn't quite thick enough sounding with a Cinemag transformer.

Not sure what else I'd suggest. Maybe something to give a slight bumo in the lows a la U47. Maybe try a valve with a low-ish output Z and a transformer in the BV8 direction. Maybe even an OEP 1:6.45 in reverse. I seem to remember the inductance was in the right range. Otherwise, the G7 circuit (with Sowter) sounded good with the M7.

 

[geoff004]

Has anyone replaced the transformer in the ACM-1200?
A buddy of mine bought one and a Tab-Funkenwerk replacement transformer, but he can't find any information about how to swap it out.
I haven't seen it first hand - he says that the leads from the Tab transformer don't match the stock tranny.
Is there any potential harm in installing it incorrectly?

 

[rodabod]

Is there any potential harm in installing it incorrectly?

Not really, unless you do something silly and connect wires to places where the transformer wasn't connected before. Two wires for primary, two wires for secondary, maybe a shield wire too. It isn't rocket science, so it's worthwhile sitting down with the information you (or your friend) have and working it out.

 

[mushy]

I actually have a pair of 5751s I am using. My thinking is this: I have an M7 based gefell that I love. I also enjoy a good c12 but I've never liked a single knock off. I'm trying to balance the brightness without treading on the territory covered by my gefell. Of course I'll keep modding until I get it right but hey, that's half the fun.

Thanks for the advice, Roddy. Anyone else have personal experience with this combo?

 

[electric]

I finally tested my groupbuy this weekend. (3 mics, 4 pre's). Everything works great except my ACM 1200 power supply is DOA. Anyone else have this problem? Wondering if there is a simple quick solution. Wont have time to debug for a while.

Regards,
Electric

 

[Paul G]

I finally tested my groupbuy this weekend. (3 mics, 4 pre's). Everything works great except my ACM 1200 power supply is DOA. Anyone else have this problem? Wondering if there is a simple quick solution. Wont have time to debug for a while.

Regards,
Electric

You checked the fuse, right?  Someone had a holder that was a little funky.

;D

 

[rodabod]

I finally tested my groupbuy this weekend. (3 mics, 4 pre's). Everything works great except my ACM 1200 power supply is DOA. Anyone else have this problem? Wondering if there is a simple quick solution. Wont have time to debug for a while.

Heater or HT?

If the latter, check the ~2W resistor isn't open circuit. Otherwise, trace backwards; these are simple supplies.

 

[electric]

thanks guys. ill start with the above advise.

simple is good. i dont have time for a complex project.

luckily all the preamps work great.

regards,
electric

 

[rodabod]

Try locating the Nady or Apex (TCM1050) PSU schematic. Should be the same or very similar.

 

[Nikbeat]

Hey I don't know if I just wasted a load of dosh on new transformers for my ACM3's  ???
I just read through the post and found that Marik is not in favour of changing the stock transformer to a Lundahl 2912
has anyone tried this mod? and what was the result.
I guess I was a bit to eager to get these mics sounding better 
I will give it a go later today and maybe post a few files of before and after as room mics for drums.

 

[mushy]

http://www.compasspointstudios.com/lucas/bulldog-tnc_upgrades.html

I've ordered two T47's.  According to Oliver, they are machine wound BV8s with off the shelf laminations.

The schematic/BOM of their simplified U47 circuit is here:

http://recforums.prosoundweb.com/index.php/fa/13125/20485/

And the related thread on PSW is here:

http://recforums.prosoundweb.com/index.php/mv/msg/16069/0/2672/20485/

 

[RightOnMusic]

yeah i got my 49inspired xfrmr and PCB the other day, but no BOM exists for the 49 version of the PCB...  I'm anxious to get this mod crackin' already, but i don't have the necessary information....