MagnetoSound
Well-known member
No harm in trying another shim. It is possible that what is already there is less than even all the way round. Do you have a good clean surface on the bottom of the diaphragm edge?
AKG D12 repair attempt...
- Thread starter SSLtech
- Start date
Help Support GroupDIY Audio Forum:
OK, I think I'll give up on this particular D12 as a kick mic, and I'll reassign it to a bass amp mic role. After the last round of work, there is some improvement, but not really more bass. Overall, it just sounds a bit cleaner to me. I actually like how it sounds combined with the D112. The D112 adds the deep end and the highs while the D12 brings out the Warwick growl that I love. I moderately regret that I dumped that transformer, it was adding some transformer distortion that was good for the same purpose.
Over the weekend I have desoldered the membrane again, added an extra shim (nothing fancy, just a single sheet of 150g photo paper). While I was at it, I've used a magnetised phillips screwdriver to pick away all the "dirt" from the membrane which are of course little metal oxide particles. This takes a lot longer to do it properly than I would have thought. I've done this already but not thoroughly enough -- just running a screwdriver over the surface won't do it. I also made sure that there was good airflow through the core of the capsule (between the hole under the membrane and the entrance to the reflex chamber). Testing with a sine wave, now there is no buzz from the membrane (which now makes it a lot harder to hear below 150Hz). I am able to tighten all six screws quite tightly without buzz appearing.
Question: any idea what the other three screws (the recessed ones) are for? Looking at the service document from above (http://www.akg.com/mediendatenbank2/psfile/datei/85/d12443e17c7c62d7.pdf, page 3), it appears as if they might be for adjusting the spacing of something inside the capsule. Could they be used for tuning something like the position of the magnet relative to the gap or something?
The other thing I can think of is that the bass chamber has some gaps where I closed it up, due to me not doing an 'airtight' solder. That's probably not really fortunate for a Heimholtz resonator, but I would be surprised if it made that much difference. Any more ideas or should I just try to ebay another one instead?
Anyway, thanks for the help so far. Even if I didn't manage to get the bass response I expected, I still learned a lot from this thread.
Cheers,
Vik
Over the weekend I have desoldered the membrane again, added an extra shim (nothing fancy, just a single sheet of 150g photo paper). While I was at it, I've used a magnetised phillips screwdriver to pick away all the "dirt" from the membrane which are of course little metal oxide particles. This takes a lot longer to do it properly than I would have thought. I've done this already but not thoroughly enough -- just running a screwdriver over the surface won't do it. I also made sure that there was good airflow through the core of the capsule (between the hole under the membrane and the entrance to the reflex chamber). Testing with a sine wave, now there is no buzz from the membrane (which now makes it a lot harder to hear below 150Hz). I am able to tighten all six screws quite tightly without buzz appearing.
Question: any idea what the other three screws (the recessed ones) are for? Looking at the service document from above (http://www.akg.com/mediendatenbank2/psfile/datei/85/d12443e17c7c62d7.pdf, page 3), it appears as if they might be for adjusting the spacing of something inside the capsule. Could they be used for tuning something like the position of the magnet relative to the gap or something?
The other thing I can think of is that the bass chamber has some gaps where I closed it up, due to me not doing an 'airtight' solder. That's probably not really fortunate for a Heimholtz resonator, but I would be surprised if it made that much difference. Any more ideas or should I just try to ebay another one instead?
Anyway, thanks for the help so far. Even if I didn't manage to get the bass response I expected, I still learned a lot from this thread.
Cheers,
Vik
One more thing: This was mentioned a couple of times already, but I think it wasn't emphasised enough: Do not ever, ever, ever, ever put a screwdriver near the magnet (like for picking off metal particles next to the coil) while the membrane is on. If you want to remove the magnetised bits of oxide from the membrane, you MUST unsolder and remove it (it's not as hard as it sounds).
I knew about the magnet and I thought I was holding the screwdriver tight. But the magnet just grabbed it in a blink of an eye, and before I realised, the screwdriver was already very firmly stuck to the magnet, pinning the membrane down. I was very, very, very, very lucky that the screwdriver was a flat head and it landed with the flat side. Otherwise I would now have a hole in a membrane and I would be crying like a little girl...
I thought I'd share this for those who are, unlike me, willing to learn from other people's mistakes
I knew about the magnet and I thought I was holding the screwdriver tight. But the magnet just grabbed it in a blink of an eye, and before I realised, the screwdriver was already very firmly stuck to the magnet, pinning the membrane down. I was very, very, very, very lucky that the screwdriver was a flat head and it landed with the flat side. Otherwise I would now have a hole in a membrane and I would be crying like a little girl...
I thought I'd share this for those who are, unlike me, willing to learn from other people's mistakes
craptical
Well-known member
Vik said:
Just put the tranny in a box w. xlrs in-out and you can use it whenever you like!
/Dave
bkbirge
Well-known member
A bit of necrothreading here but I can't find the answer with a search...
I've got a D12(e?) with an on/off switch installed. It sounds great, nice and punchy with rich low mids EXCEPT it has a horrible buzzing sound that is too audible to really make the mic usable. I haven't put a scope on it but I'd guess it's a ground hum harmonic. Anyone have any ideas what could be causing it? It did this at the old studio and I thought it was my wiring but it also does it at the new place. How would you experts go about troubleshooting this? Thanks! - Brian
I've got a D12(e?) with an on/off switch installed. It sounds great, nice and punchy with rich low mids EXCEPT it has a horrible buzzing sound that is too audible to really make the mic usable. I haven't put a scope on it but I'd guess it's a ground hum harmonic. Anyone have any ideas what could be causing it? It did this at the old studio and I thought it was my wiring but it also does it at the new place. How would you experts go about troubleshooting this? Thanks! - Brian
Hi there,
Why, the thread's still fresh I just got too busy to waste more time on my D12, and decided to postpone my reply until I actually got something new to say. (Thanks Dave for the suggestion to box up the transformer, I will very likely do that).
When I pulled my D12 apart, there was terrible ground hum when the capsule was no longer earthed. It is normally earthed through the chassis / internal shockmount, and when I pulled it out for disassembly, it started to buzz straight away. So checking the earth connection would be a good place to start, I think.
Cheers,
Vik
Why, the thread's still fresh
I just got too busy to waste more time on my D12, and decided to postpone my reply until I actually got something new to say. (Thanks Dave for the suggestion to box up the transformer, I will very likely do that).When I pulled my D12 apart, there was terrible ground hum when the capsule was no longer earthed. It is normally earthed through the chassis / internal shockmount, and when I pulled it out for disassembly, it started to buzz straight away. So checking the earth connection would be a good place to start, I think.
Cheers,
Vik
bkbirge
Well-known member
Thanks Vik, I'll look there tonight! - Chip
Vik said:Hi there,
Why, the thread's still fresh
When I pulled my D12 apart, there was terrible ground hum when the capsule was no longer earthed. It is normally earthed through the chassis / internal shockmount, and when I pulled it out for disassembly, it started to buzz straight away. So checking the earth connection would be a good place to start, I think.
Cheers,
Vik
I want to add my name to the list of thank you's. I just got one of my D12E's working like new again! The pictures were a huge help. Desoldering and resoldering those tiny magnet wires sure is a PITA though. Tuning the capsule wasn't as hard as I thought it would be once everything was cleaned up.
It really is great to have the resource of this community. I sincerely thank everyone involved!
It really is great to have the resource of this community. I sincerely thank everyone involved!
michaelfav
New member
- Joined
- Aug 17, 2010
- Messages
- 1
I too recently dug into my faulty D12 after I tried to sell it on eBay and got it returned broken. The membrane filament wire on the diaphram shattered. Does anyone know where I could locate one? I have contacted AKG in Austria and informed they discontinued repair two years ago.
steenamaroo
Well-known member
- Joined
- Dec 23, 2009
- Messages
- 83
hey guys!
some fantastic info in here! thanks very much to all of you.
i have a quick question regarding a d12e that i bought. i was led to believe that it was 'faulty' (lacking in bass), but now that i have it and have compared it to other mics, i'm not sure that it is.
it sounds fine, very 'wooly' and a little dull on speech.
the only hint of a problem i can find is that it reproduces 60hz + below at a much lower level than say, a d112.
i recorded a sine wave curve and it shows the d12 getting louder as the freq increase, but with d112, it's pretty much consistent.
big question is, is it faulty, or is that the way d12s are?
the mic is exceptionally clean. in fact, it may as well be new! inside and out!
**update.
sadly i don't have a kick drum or decent bass instrument to test with, but i sent a recording of a kick drum to a sub and miced with
d12,d112 and sm7b in that order.
clip is at www.webforni.com/steen/3mics.mp3
seems like the mic might be fine to me? but i'm still made nervous cos of the 'bucketloads of low end' that you read about from the d12....
some fantastic info in here! thanks very much to all of you.
i have a quick question regarding a d12e that i bought. i was led to believe that it was 'faulty' (lacking in bass), but now that i have it and have compared it to other mics, i'm not sure that it is.
it sounds fine, very 'wooly' and a little dull on speech.
the only hint of a problem i can find is that it reproduces 60hz + below at a much lower level than say, a d112.
i recorded a sine wave curve and it shows the d12 getting louder as the freq increase, but with d112, it's pretty much consistent.
big question is, is it faulty, or is that the way d12s are?
the mic is exceptionally clean. in fact, it may as well be new! inside and out!
**update.
sadly i don't have a kick drum or decent bass instrument to test with, but i sent a recording of a kick drum to a sub and miced with
d12,d112 and sm7b in that order.
clip is at www.webforni.com/steen/3mics.mp3
seems like the mic might be fine to me? but i'm still made nervous cos of the 'bucketloads of low end' that you read about from the d12....
wmb
Well-known member
(Question in last pragraph)
It's been a long time since I've logged in here but a search brought me back and boy am I glad. This is a fascinating thread! I was auditioning a new bass amp in my studio this weekend when I decided to try my D12 on the cabinet. I couldn't find my trusty D12 (with NOS capsule) which was mildly troubling but I have 3 more (long story) in various conditions so I just grabbed the one I knew to be my 2nd favorite (usually it mic's the low rotor of my 147 cabinet). On the bass cab the mids were stupendous and the lows were ok but it seemed to have a little bit of buzz or distortion that I don't get when I use it on the leslie. This got me concerned and thinking.
I remembered where my favorite D12 had been placed and I put it on the stand to replace the other. The distortion/buzz was not present. Hmmmm. So here I am after some searches.
The medium version of the story of how I got 4 goes something like this. I bought one (AKG, plastic frame) and then got an opportunity to buy 3 more of unknown working order for pretty cheap so I did. The other three were not badged AKG, they are branded L.I.A.R.E. and I think they say Italy on them as well. They all have metal frames and instead of having felt covering the capsule it is a fine screen. I don't think they are knock-offs because everything about the capsules and other internals look identical all the D12 photos I've seen and the capsule cover looks like those at this site http://www.avatarzenekar.hu/files/d12/. My LIARE D12's all measure approximately 50 Ohms. None have transformers.
Of the three LIARE mics one is clearly the best sounding but with the slight buzz noted above, the second has some hum and the back cover is really trashed and barely stays on the mic, the third and weakest (practically not working) is also in decent cosmetic condition. My original intent was to try and track down the buzz in mic (#1) and then that migrated into consolidating the more trashed mic (#2) that sounded okay into the casing of the good looking but poor performing #3.
After finding this thread I decided to change course and see if I could get mic #3 to work better and then possibly work my way through all three mic's to see if there is life in all of them yet. Where can I find this sweep test procedure outlined? Searches were not fruitful. Is it just connecting the mic connector to a headphone out and slowly turn up till it becomes audible like a tiny speaker?
Thanks for all the info in this thread
Billy B
It's been a long time since I've logged in here but a search brought me back and boy am I glad. This is a fascinating thread! I was auditioning a new bass amp in my studio this weekend when I decided to try my D12 on the cabinet. I couldn't find my trusty D12 (with NOS capsule) which was mildly troubling but I have 3 more (long story) in various conditions so I just grabbed the one I knew to be my 2nd favorite (usually it mic's the low rotor of my 147 cabinet). On the bass cab the mids were stupendous and the lows were ok but it seemed to have a little bit of buzz or distortion that I don't get when I use it on the leslie. This got me concerned and thinking.
I remembered where my favorite D12 had been placed and I put it on the stand to replace the other. The distortion/buzz was not present. Hmmmm. So here I am after some searches.
The medium version of the story of how I got 4 goes something like this. I bought one (AKG, plastic frame) and then got an opportunity to buy 3 more of unknown working order for pretty cheap so I did. The other three were not badged AKG, they are branded L.I.A.R.E. and I think they say Italy on them as well. They all have metal frames and instead of having felt covering the capsule it is a fine screen. I don't think they are knock-offs because everything about the capsules and other internals look identical all the D12 photos I've seen and the capsule cover looks like those at this site http://www.avatarzenekar.hu/files/d12/. My LIARE D12's all measure approximately 50 Ohms. None have transformers.
Of the three LIARE mics one is clearly the best sounding but with the slight buzz noted above, the second has some hum and the back cover is really trashed and barely stays on the mic, the third and weakest (practically not working) is also in decent cosmetic condition. My original intent was to try and track down the buzz in mic (#1) and then that migrated into consolidating the more trashed mic (#2) that sounded okay into the casing of the good looking but poor performing #3.
After finding this thread I decided to change course and see if I could get mic #3 to work better and then possibly work my way through all three mic's to see if there is life in all of them yet. Where can I find this sweep test procedure outlined? Searches were not fruitful. Is it just connecting the mic connector to a headphone out and slowly turn up till it becomes audible like a tiny speaker?
Thanks for all the info in this thread
Billy B
Biasrocks
Well-known member
Hey guys,
I've got a D12 here that's exhibiting some issues with high SPL applications.
Notably the bottom end folds up when using it inside of a kick drum. Top end
stays intact but nothing from about 500hz down.
The mic sounds fine in front of my Ampeg B15. But in the kick it's shutting down.
Curious, if anyone has had a similar issue.
I've read earlier about keeping the tension on the capsule screws relatively light so I've
only tightened them with a light tension. Should I try increasing the tension on
those guys to see if I can get a proper response on the kick?
Mark
I've got a D12 here that's exhibiting some issues with high SPL applications.
Notably the bottom end folds up when using it inside of a kick drum. Top end
stays intact but nothing from about 500hz down.
The mic sounds fine in front of my Ampeg B15. But in the kick it's shutting down.
Curious, if anyone has had a similar issue.
I've read earlier about keeping the tension on the capsule screws relatively light so I've
only tightened them with a light tension. Should I try increasing the tension on
those guys to see if I can get a proper response on the kick?
Mark
s2udio
Well-known member
You need to take it apart.....see page 1 and read again ? its all there
If the diapghams knackered ..no DC res after CLOSE inspection ,then it,s probably game over.
The signal sweep method "re rodabods post " is described here......seek and find !
If the diapghams knackered ..no DC res after CLOSE inspection ,then it,s probably game over.
The signal sweep method "re rodabods post " is described here......seek and find !
Glad to help....esspecialy a mic expert like yourselfzebra50 said:
wmb
Well-known member
s2udio said:
If you are referring to the second post in the thread then I found that right away. I was just looking for a little more detail. It must not be that harrowing since the descriptions are so light. I think the thing that got me worried was one post mentioning a tube powered signal generator. I will wing it with super low volume from a headphone jack working my way up and see what happens. The mic barely worked anyway.
s2udio
Well-known member
s2udio said:
andre tchmil
Well-known member
If anyone ever wants to part with a membrane for a D12, let me know;
I have a complete mic except for this part.
thanks
I have a complete mic except for this part.
thanks
