Neumann TLM103 modification (new Plexiglas capsule base)

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MS Vienna

Well-known member
Joined
Feb 1, 2016
Messages
110
Location
Vienna, AUSTRIA
Hi,

the TLM103´s capsule mounting was the first of it´s kind and a bit unusual. Due to the very simple mechanical construction of the mic (obviously to achieve a low selling price) the capsule is directly mounted on the PCB. The PCB is fixed in the mic´s housing by a rubber ring.

Unlike any Neumann LDC mics before the capsule sits quite low in the grille and sees a slightly unfortunate acoustical environment. While the grillecap is a proven design (U67, U87 and similar) the base plane on which the capsule sits (PCB) is way below the lower grille entry, basically creating a shallow cavity.
DSCF7243e_kl_zps3qzslm8j.jpg


I think the TLM103 is a great mic for the money with very low noise and good off axis behaviour. Soundwise it leaves some room for improvement. Since nothing can be really done about the capsule or the electronics (by me), I focused on the acoustical shortcomings inside the grille. I had good success with that on my Brauner VM1 so I was encouraged to give it a go on the 103.
If you do a search for U67 capsule assembly pictures you´ll notice that the capsule stands on a polished plastic dome that acts like a diffusor. That´s what I wanted.

After disassembling and with a piece of Plexiglas that´s gonna become the new capsule base.
DSCF4152e_kl_zpsa4ny7blw.jpg


BTW the original "elastic" capsule mount isn´t elastic at all...
DSCF4153_kl_zpsr6n3knhu.jpg


Plexi base before finishing
DSCF7170e_kl_zpshdudtcsr.jpg

For tips how to manufacture this please see this posting:
http://groupdiy.com/index.php?topic=63305.msg802223#msg802223

Polished and mounted
DSCF7187e_kl2_zpskjjr0ebi.jpg

I did make a new elastic capsule mount too. Inside the brass part there´s a threaded rubber element like the ones usually used for the purpose. The brass enclosure limits the tilting angle in case the mic receives a physical blow and adds weight (reduces vibration transmission further)

I drilled a hole to accommodate one larger component on the PCB.
DSCF7239e_kl_zpsildlxoxf.jpg


This new base assembly shifts the capsule´s position upwards inside the grille to roughly the same position as found in the U87.
DSCF7240e_kl_zps3spwyzkh.jpg


DSCF7231e_kl_zpsx84zuiik.jpg


DSCF7236e_kl_zpssu08m2md.jpg


And of course the plexi dome starts right below the grille entry - just like in a U67, avoiding any resonance artefacts.
DSCF7244e_kl_zpscjnftu70.jpg



I never felt that my TLM103s´ top end sounded notably harsh (they are relatively early ones from 2001). But there was a certain unevenness thoughout it´s frequency range that I didn´t like - like the midrange being sort of separated from the top end.
The mod certainly helped. The sound is much more homogeneous. It´s like everything just fell in place. The topend is smoother, the (upper) midrange apears to be slightly boosted and the bass slightly less dry/punchy but a bit more on the mellow side.
For my taste definitely an improvement and worth the effort.





 
micaddict said:
On the downside, I almost regret I sold my TLM103.  :-\

I did always wonder why the capsule sat so low.

Actually I was considering to sell mine too  ;) I just wanted to try this before, there was nothing to loose. Just invest some time and gain some valuable experience. Since the mod is fully reversible the option to sell is still available. But I certainly won´t reverse it. I´m not in a hurry but eventually I will do the  second one too and  have a very nice pair then.

I think the low capsule position is a necessity with this type of construction. This capsule has even more weight than a K67 so mounting it on a higher rod may damage the PCB in case of a fall or blow because of increased leverage.
The folks at Neumann are pretty clever and have decades of experience available. I´m sure they have good reason for design decisions like that.  After all things like that have to make sense from the business perspective too.

 
JessJackson said:
nice work mate, do you fancy making another?

I also received a PM with  this request. Yes, of course I could do that. I want to make another one for my second TLM103 anyway, so I could make two additional ones in the process.

My descrition of how I perceive the sound is of course subjective. I look forward to record a comparison between the modified and stock TLM103 for you to listen and consider yourself.

Mine have consecutive serial numbers so are practically identical otherwise.
 

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I'm on a poor system, so I can't reallys ay anything sensible about the difference, yet.
The Schoeps has considerably less bass, even on my system, though.
To be continued.

Nice guitar BTW.
Looks like a Martin D-41, but with a vintage style (through slot saddle) bridge.
 
Eve on laptop speakers i hear the difference in hi an hi-mid area. That's great improvement :)
I never liked TLM103, but now maybe i will consider as an option for my studio in some future ;)
 
Not a night&day difference but given that the capsule, electronics and grillcap itself remained unchanged it´s quite considerable. 

The guitar started life as 1980´s Sigma D41. I started customizing it in 1996 step by step and finally got the sound I wanted by 2003. Compared it to numerous Martins and other guitars since and yet there wasn´t a single one that made me wanna change. It´s perfect for the purpose it has to serve.
BTW, I used  a yellow Dunlop Tortex here (0,76ish mm) to emphasize the highs a bit (the heavier green one produces a proper balance in the mix).
 
JerryPbury said:
I know this is an old post but has the OP considered making these new capsule mounts on a 3D printer?

I meanwhile redid it with a new shape and higher arching. I´m happy with it and also did my second TLM103 that way. Since I have the material, machinery and ability to craft it manually it was quickest to do these one-offs that way.
Plexiglas is the perfect material for it and since it´s Neumann mics I wanted to get the most out of it. 

I actually have no idea if it´s possible to get the same end result with 3D printing. These days probably yes.
 
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