Another Apex 205 mod thread. I need some help.

chrisghost

New member
Has anyone here put the Lundahl LL2913 transformer in the Apex 205?

There's a good internet page on how to install the Cinamag CM 9888 into the Apex 210 ( http://www.morphproductions.com/apex210transformermod.htm )

Looking at that page it seemed a piece of cake to replace a transformer. Based on Micheal Jolly posts I ordered Lundahl LL2911 transformers, they sent me LL2913, apparently they're the same.

The problem is the Lundahl has 11 solder points (Cinamag has 4, like the original in the Apex 205). Does anyone know what to connect where?
 
I did the Lundahl mod, but had an issue with polarity

I followed Mike Joly's thread at: Ribbon mic mod - part 1 - Apex 205 - Hometracked, and also swapped in Lundahl 2912 transformers. The two mics I modded work and sound great, and I can post the details with photos if the owner of this thead or anyone else is interested in how to do the wiring.

But there were some anomalies: Below is a thread I posted on Gear slutz on this issue:

"Has anyone tried this ribbon mic mod recently? I did and discovered the Chinese manufacturer has completely rotated the internal components (since MJ did that post) so that the transformer is now facing the front. The ribbon motor assembly cannot be orientated any other way as the two screws that locate the headbasket (the small one and the large knurled one) are different sizes. I recently modded a pair of 205s, including swapping in 2912 Lundahl transformers. I followed Lundahl's instructions and my best knowledge for wire and pin connections and discovered these modded Apex's had opposite polarity to all my other mics. My big question is: Were the 205s polarities inverted BEFORE the transformer mod? I had no reason to test them at that stage. When the mechanics were flipped by the manufacturer did the electronics follow, or are there loads of these Apex 205s being sold with inverted polarities? Can anyone check that?"

I have no had any response to that as yet. I do trust my wiring and, as mentioned, can show the details of that, so I have a strong suspicion that because the motor has been inverted the "front" of the mic no longer represents the true front according industry convention of electrical polarity and sound waves.

This isn't a biggy in practice, it just means you either use the mic back to front or invert the phase on the mixing board, or, if you do the transformer mod, swap the polarity of either the input or output wires to the transformer. But if you didn't know there was a problem it could cost time and money or just have you scratching your head needlessly.
 
I too am in the same predicament as chrisghost. If anyone can shed some light it would be greatly appreciated. I've got good soldering skills but I'm not too good at deciphering schematics.
 
I too am in the same predicament as chrisghost. If anyone can shed some light it would be greatly appreciated. I've got good soldering skills but I'm not too good at deciphering schematics.

I know what you mean with schematics. As I said I have photos of the wiring and notes on the schematics to give correct polality when the mic is addressed from the front. I spent the last couple of days double checking this. Just give me a day or two and I post it all up.

Terence
 
Thanks Terence,
I'm sure this info will be useful. Hopefully it wont be too different from the LL2913.
 
I've only come across one mic that was actually built up reversed and maybe two wired backwards. Believe me, when the women assemble these things they into a groove and do the same same the same way every time - Its just plain easier.

Once modified my last wiring check before re-assembly is to check phase against an SM-57. The back side of the 405 will cancel against the SM-57 when suspended above a speaker playing pink noise.

If your mic is out of phase just swap either; the ribbon output leads, the leads at the transformer output or the leads at the XLR. That assumes you're not one of those audiophile "absolute phase" guys. If you're are, you'll need to use a known polarity pulse tester.
 
I followed Mike Joly's thread at: Ribbon mic mod - part 1 - Apex 205 - Hometracked, and also swapped in Lundahl 2912 transformers. The two mics I modded work and sound great, and I can post the details with photos if the owner of this thead or anyone else is interested in how to do the wiring.

But there were some anomalies: Below is a thread I posted on Gear slutz on this issue:

"Has anyone tried this ribbon mic mod recently? I did and discovered the Chinese manufacturer has completely rotated the internal components (since MJ did that post) so that the transformer is now facing the front. The ribbon motor assembly cannot be orientated any other way as the two screws that locate the headbasket (the small one and the large knurled one) are different sizes. I recently modded a pair of 205s, including swapping in 2912 Lundahl transformers. I followed Lundahl's instructions and my best knowledge for wire and pin connections and discovered these modded Apex's had opposite polarity to all my other mics. My big question is: Were the 205s polarities inverted BEFORE the transformer mod? I had no reason to test them at that stage. When the mechanics were flipped by the manufacturer did the electronics follow, or are there loads of these Apex 205s being sold with inverted polarities? Can anyone check that?"

I have no had any response to that as yet. I do trust my wiring and, as mentioned, can show the details of that, so I have a strong suspicion that because the motor has been inverted the "front" of the mic no longer represents the true front according industry convention of electrical polarity and sound waves.

This isn't a biggy in practice, it just means you either use the mic back to front or invert the phase on the mixing board, or, if you do the transformer mod, swap the polarity of either the input or output wires to the transformer. But if you didn't know there was a problem it could cost time and money or just have you scratching your head needlessly.

Did you adjust the tension on the ribbon too? I've done the mod as well but did not attempt to adjust the tension on the ribbon for fear of damaging it. I would really like adjust the tension on the ribbon and would appreciate any advice on how to go about doing it with out screwing it up.

Thanks
 
Hi Guys,

I had planned to catch up with this post over the weekend but things got in the way. I should get to it this evening and put up a some phots.

Yes, I did re-tension the the ribbons in both mics. This ribbon sag issue seems quite a problem, as Mike Joly has pointed out. I'll share my details about that as well if it helps.

More later.
 
Apex 205 - Llundahl 2912 Transformer mod

Sorry again for the delay. I've posted my notes on Gearslutz as I could not upload the figures here because of the file size limit. I didn't want to reduce the images to the point where they became unclear.

Here is the link: http://www.gearslutz.com/board/low-...-ribbon-mic-transformer-mods.html#post4733353

As I mention in that post EtR, you may be better off with the shielded 2913, in case ground noise is an issue.

I'll get back with my ribbon re-tensioning experiences later, Simman. Putting this thing together has been quite an effort. I hope this helps.

-Terence
 
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I've only come across one mic that was actually built up reversed and maybe two wired backwards. Believe me, when the women assemble these things they into a groove and do the same same the same way every time - Its just plain easier.

Once modified my last wiring check before re-assembly is to check phase against an SM-57. The back side of the 405 will cancel against the SM-57 when suspended above a speaker playing pink noise.

If your mic is out of phase just swap either; the ribbon output leads, the leads at the transformer output or the leads at the XLR. That assumes you're not one of those audiophile "absolute phase" guys. If you're are, you'll need to use a known polarity pulse tester.

Thanks, Mike. This seems like more than just an assembly issue, but please see my link above.

Yes, I also tested the moded Apex mics against a dynamic, and then every other mic I had as a reality check. It was easy to see that a simple recorded tone was fully 180 degrees out of phase by zooming in on paired wave forms - the Apex and the test mic. I also used a couple of software plugs (i.e. Flux's freeby Stereo Tool) so I have no doubt these mics had their polarities back to front. Anyway, checkout my notes and let me know what you think.

Cheers,
Terence
 
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So I just completed this mod and wanted to thank Michael Joly and Terence for their large amount of information they have given here in the HR.com BBS and gearslutz.

Here are some of my experiences to add:

BOTH of my mics required ribbon adjustments. One mic was really bad and had much of the ribbon touching the silk screen/resonator plate. The other mic's ribbon was rubbing on one of the magnets. The tension was OK. So from my experience, I am 0 for 2 in the quality control department. Not a big issue as these mics are very under-priced IMO. The sagging could also simply just be a relaxation of the corrugated ribbon too. But, if you are going to buy an Apex 205, you should be aware of these kind of occurrences.

The transformers on both of my Apex 205's were facing the front of the microphone as was the case in Terence's mics. I replaced the stock transformers with Lundahl LL2913 xfmrs (w/ PCB) from K&K Audio. Wiring was done just as Terence posted in his gearslutz forum (Here). The LL2913 w/PCB did fit in this mic! At some point I saw someone say it wouldn't, but I didn't have any issues. I chose this xfmr as it is shielded.

Anyways, the mics now sound excellent. They sounded pretty good stock after ribbon adjustment. Thanks to all who have added to the Apex 205 mod information around these parts.

FYI, I also picked up a pair of "fetheads" for some extra gain with these mics and they work great.
 
So I just completed this mod and wanted to thank Michael Joly and Terence for their large amount of information they have given here in the HR.com BBS and gearslutz.

Here are some of my experiences to add:

BOTH of my mics required ribbon adjustments. One mic was really bad and had much of the ribbon touching the silk screen/resonator plate. The other mic's ribbon was rubbing on one of the magnets. The tension was OK. So from my experience, I am 0 for 2 in the quality control department. Not a big issue as these mics are very under-priced IMO. The sagging could also simply just be a relaxation of the corrugated ribbon too. But, if you are going to buy an Apex 205, you should be aware of these kind of occurrences.

The transformers on both of my Apex 205's were facing the front of the microphone as was the case in Terence's mics. I replaced the stock transformers with Lundahl LL2913 xfmrs (w/ PCB) from K&K Audio. Wiring was done just as Terence posted in his gearslutz forum (Here). The LL2913 w/PCB did fit in this mic! At some point I saw someone say it wouldn't, but I didn't have any issues. I chose this xfmr as it is shielded.

Anyways, the mics now sound excellent. They sounded pretty good stock after ribbon adjustment. Thanks to all who have added to the Apex 205 mod information around these parts.

FYI, I also picked up a pair of "fetheads" for some extra gain with these mics and they work great.

Thanks for providing the details of your mods and it's a nice reality check regarding the motor orientation. I knew I couldn't be that unlucky.

I was was always curious to know if the PCB version of the transformer would work! You probably used the best option - as you say it's already shielded. Having said that there has been zero problems with mine.

I agree the mics sounded pretty good beforehand. My experience was pre-mod they had a kind of thickness in the midrange that I liked on some vocals. The more open sound post-mod I like on acoustic guitar and generally. I often use them XY paired as stereo room mics when doing fun "live" takes. Check out this utube if you are interested (no claims for performance) - straight out of the can with just a touch of reverb -

https://www.youtube.com/watch?v=EUr0ZNz859U

- the 205s are are just below the frame out of shot about 3ft from each guitar. I love how ribbons can soften harsh transients in this kind of set-up. FYI that's an SM7b on the vocal.

-Terence
 
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