R/E/P => R/E/P Archives => Klaus Heyne's Mic Lab => Topic started by: TrueThomas on August 22, 2010, 06:35:47 AM
Title: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 22, 2010, 06:35:47 AM
I have 2 KMS105, one was bought used, and turned out to be moisture sensitive, though it works fine if kept dry, still its not a great deal of use as a live vocal mic, the other is new.
I bought these as the best available live vocal mic, and they do significantly outperform anything else I've tried for that purpose.
I had hoped to use them in the studio too for instruments, but I am finding that in the more critical listening environment of the studio they are rather hard and thin sounding, in a way I am learning to associate with mics with complex circuits full of surface mount parts.
So I am wondering do people here think that the KMS105 would be improved by replacing the electronics? I am talking about outright replacement board and all so that the original board can be put back at any time and the mic restored to stock. In any case modding a surface mount board is no fun at all.
I have noticed that the capsules actually fit on my Peluso CEMC6 bodies, though I haven't yet had the nerve to turn them on like that, any reason not to?
what do you think about outright replacing the electronics with a very simple fet circuit? if so which one?
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: gk on August 22, 2010, 09:54:46 AM
The moisture problem is the reason i never bought any for my live mic arsenal; would be good to have info on this---
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: bob ebeling on August 22, 2010, 10:23:45 AM
My favorite mic for 'throw it in front of anything'. Like most peoples sm57. Also, the hypercardiod pattern of the 105 helped me get some pretty impressive things done in Holiday Inn hotel rooms. Never had the issues you're having with moisture, but I don't use it for live use and could imagine the wrong singer putting an end to it quickly.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 22, 2010, 10:28:55 AM
I suspect the moisture problems are caused by nicotine contamination. Certainly capsule contamination of some sort. The mic works best close up though, it's designed with a bass rolloff and low output to compensate for this.
I have had no problems with the new one so far though.
What do people think about the electronics? As a SDC for instruments with the grille removed it doesn't do it for me despite the capsule likely being better than my other SDCs.
I'd especially like to get some use out of the unsaleable moisture sensitive one by using it on instruments.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: jpaul_bordon on August 22, 2010, 12:36:25 PM
Taking off the windscreens really opened up the mic for me on acoustic instruments! It seem to have taken out quite a bit of the mid harsh you had described. Probably a by-product of improving the high's.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: bob ebeling on August 22, 2010, 03:04:29 PM
I thought it is basically a 185 with a fancy triple basket.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 24, 2010, 07:05:38 AM
bob ebeling wrote on Sun, 22 August 2010 20:04
I thought it is basically a 185 with a fancy triple basket.
It is that. It also has a heavy body to minimise handling noise, and a permanent HPF to compensate for proximity effect. May also have a reduced output level, but I don't have a 185 to compare.
The HPF makes it pretty useless for guitar in the studio though.
I have just done some recording on irish bouzouki using the KMS105 capsules on peluso CEMC6 bodies. It's not perfect, but its a lot better than using the KMS105 body, and the capsules are less bright and aggressive than the peluso ones. This would seem to support my idea of building alternative bodies for the KMS105 capsules.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: gk on August 24, 2010, 09:15:21 AM
I have a KMS84 that has been used extensively for live, and studio w/o ever an issue. Always a great sound. But I've worked with traveling live engineers that have seen more than one 105 with cutout problems, --would be good to know if this problem has been dealt with, why it exists, and what to do about it besides taking the hi road with some other mic.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 24, 2010, 10:28:38 AM
re the moisture cutout issues, i think its pretty clear that the issue is capsule contamination, and apparently nicotine is one of the worst contaminants for this, so if the singer is a smoker or the mic has been used in smoky environments it's going to be more likely. That could also explain peoples varied experience with reliability of the mic.
There is a thread on the neumann forum about this, but last I checked neumann were being rather evasive about recognising the problem as anything they could or should do anything about.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: gk on August 24, 2010, 12:47:24 PM
The situations I refer to were NOT smoky environments, any mic in a smoke kind of environment would have issues--
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 24, 2010, 02:02:30 PM
... but if the singer were a smoker, even if if the environment were not smoky? There could still be nicotine contamination? I don't know how well they tolerate beer or other commonly imbibed substances by singers....
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: Jim Williams on August 28, 2010, 12:36:40 PM
Replacing the surface mount pcb with a through hole discrete component alternate circuit can certainly be done. As with everything audio, it's a matter of cost and demand. If there is a demand that exceeds the costs it will be done. Just as there are alternative capsule choices available, someone, if not me will make replacement pcb's for common mics, it's the next stage.
The noise floor can be improved as better jfets are now available to the common 2SK107/2SK170/2SK30/J305 parts.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on August 29, 2010, 10:30:39 AM
Would you care to recommend such a fet?
I'd like to try to make a replacement circuit myself. Any suggestions about circuit topology also gratefully received.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: ssltech on September 01, 2010, 08:04:49 AM
Several people have mentioned nicotine contamination.
Nicotine?
...Or tar?
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: TrueThomas on September 01, 2010, 06:51:17 PM
Apparently it has a special talent for getting between the membrane and the backplate and creates a bridge that changes resistance with moisture. Cleaning the outside of the diaphragm then doesn't help because the contamination is behind.
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: Klaus Heyne on September 01, 2010, 11:07:38 PM
Usually just moisture can get between membrane and backplate(s); the space is too confined to invite more stuff.
The break-down of capacitance does usually not happen through moisture in the 40
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: gk on September 02, 2010, 11:09:41 PM
Does the + polarization of the diaphragm attract stray electrons and other polar solvents (water), and polar contaminants in the air ?
Title: Re: Neumann KMS105 (thoughts? mods?)
Post by: Klaus Heyne on September 04, 2010, 08:35:14 PM
I am pretty sure that the KMS105 follows the KM8x schematic, whereby the diaphragm is at ground potential.
The effect of electrostatic attraction on systems with the diaphragm at ground potential is somewhat reduced, as the polarised capacitor side (the backplate) is physically shielded from direct impact of flying objects, compared to the set up where the diaphragm is isolated from ground (almost all Neumann LD capsules), and where the full electrostatic attraction effect is felt.