MKH415T servicing?
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Grim Reaper
Well-known member
I found a pair of incomplete Sennheiser MKH boddies ,
Includes the electronics and capsule minus the shotgun interference tube ,
Not sure if there in working condition or not ,
I found a funny story about the evolution of the mic , apparently the designer ,in response to a question at the launch took out a hacksaw and asked 'how much directivity do you need ' then proceeded to cut the mic down to size , and I think it was out of that the shorter MKH416 was born .
Overview of the MKH series here ,
https://assets.sennheiser.com/global-downloads/file/11061/MKH-Story_WhitePaper_en.pdf
service manual here ,
https://ia804509.us.archive.org/11/...ER_EN_DE/MKH415T_SM_SENNHEISER_EN_DE_text.pdf
I couldnt find the P48 mod , it is apparently possible to do the modification to the mic internally but theres not much space , others make up the circuit in a seperate enclosure , anyone who's done the mod or made up an external P48 to T12 adapter or has surplus shotgun tubes might point me in the right direction .
Includes the electronics and capsule minus the shotgun interference tube ,
Not sure if there in working condition or not ,
I found a funny story about the evolution of the mic , apparently the designer ,in response to a question at the launch took out a hacksaw and asked 'how much directivity do you need ' then proceeded to cut the mic down to size , and I think it was out of that the shorter MKH416 was born .
Overview of the MKH series here ,
https://assets.sennheiser.com/global-downloads/file/11061/MKH-Story_WhitePaper_en.pdf
service manual here ,
https://ia804509.us.archive.org/11/...ER_EN_DE/MKH415T_SM_SENNHEISER_EN_DE_text.pdf
I couldnt find the P48 mod , it is apparently possible to do the modification to the mic internally but theres not much space , others make up the circuit in a seperate enclosure , anyone who's done the mod or made up an external P48 to T12 adapter or has surplus shotgun tubes might point me in the right direction .
https://microphone-shop.com/T12_instruction.pdfHeres an adapter pcb designed to fit inside the microphone .
Grim Reaper
Well-known member
Where can I purchase the conversion boards?
Grim Reaper
Well-known member
Icantthinkofaname
Well-known member
I remember reading something similar. I think the MKH 415 was somewhere between the size it was and a long shotgun like the 816 before being cut down. I don't know the accuracy of it, I saw it on Recording Hacks which says it's "Sennheiser lore".
I found a few BBC R&D reports on RF microphones which will be of interest ,
https://downloads.bbc.co.uk/rd/pubs/reports/1966-32.pdf
https://downloads.bbc.co.uk/rd/pubs/reports/1966-19.pdf
https://downloads.bbc.co.uk/rd/pubs/reports/1955-24.pdf
https://downloads.bbc.co.uk/rd/pubs/reports/1966-32.pdf
https://downloads.bbc.co.uk/rd/pubs/reports/1966-19.pdf
https://downloads.bbc.co.uk/rd/pubs/reports/1955-24.pdf
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Ever seen the Stephens Rf mic EMRR ?
looks nice ,
I notice from the BBC reports the AKG RF mic gives the lowest self noise they ever witnessed ,
Seems like I have one of the earlier 415's and a later SMD version of the 416 on the way , there both XLR so hopefully they werent fried with P48 , although maybe an inadvertant short might be more likely to damage to the supply , who knows , the seller assures me he hasnt tested them , the fact that the cases are missing points to possible problems , luck of the draw on this one , there coming to me cheap so its worth the punt ,as the gambling man says .
https://www.ebay.de/itm/144707817008I'm tempted by that ,
but if anyone else wants to grab it do ,
Rogs , it could be the missing piece of the puzzle ,
These mics are clean as the proverbial whistle , be interesting to add some tube/transformer into the signal path to closeline any nasty peaks .
Theres seems to be several reports of less than satisfactory results bucking down phantom power ,
I see theres a dedicated T style battery psu from Senn ,long since gone from the product range , sports three position attenuator and HPF toggles ,
A seriously usable piece of kit alongside its counterpart .
looks nice ,
I notice from the BBC reports the AKG RF mic gives the lowest self noise they ever witnessed ,
Seems like I have one of the earlier 415's and a later SMD version of the 416 on the way , there both XLR so hopefully they werent fried with P48 , although maybe an inadvertant short might be more likely to damage to the supply , who knows , the seller assures me he hasnt tested them , the fact that the cases are missing points to possible problems , luck of the draw on this one , there coming to me cheap so its worth the punt ,as the gambling man says .
https://www.ebay.de/itm/144707817008I'm tempted by that ,
but if anyone else wants to grab it do ,
Rogs , it could be the missing piece of the puzzle ,
These mics are clean as the proverbial whistle , be interesting to add some tube/transformer into the signal path to closeline any nasty peaks .
Theres seems to be several reports of less than satisfactory results bucking down phantom power ,
I see theres a dedicated T style battery psu from Senn ,long since gone from the product range , sports three position attenuator and HPF toggles ,
A seriously usable piece of kit alongside its counterpart .
rogs
Well-known member
The problem with that type of capsule -- and I suspect almost all SDC capsiules? -- is that the capactiance is likely to be only around 40pF.
With the inductors I have used for my experimental RF mic, that kind of value is just too low to get good results.
It would seem that most - if not all? - commercial RF mics from Sennheiser and Rode use SDC capsules.... And the inductors used in their circuits are obviously designed to work with those capsules....
The trouble with RF bias hobby mics is finding someone with the expertise - and inclination? - to design inductors suitable for use with lower capacitance capsules.
I found the inductors I use by chance... They are not perfect for the task, but are quite close when used with caspules with a capacitance of 65pF or more.
I've never come across any alternative 'off the shelf' inductors that are close to being useful for this task - especially for use with lower value capsules.
It seems that 'old style' IF can format RF transformers are now only made in India, and are becomng rarer all the time.
So I'm stuck with LDCs and larger diameter bodies for my experiments....
In fact, it could be that these are the only LDC RF bias mics avaialable anywhere?...
That's probably because they have limited applications, compared to the Sennheiser and Rode shotgun mic uses.
At the moment I'm looking at trying out one of the Arienne Audio 'flat K.47' capsules in a figure of 8 configuration.
The fact that those capsules are matched to within 1dB could present some interesting results....
Used with a second, separately housed, cardioid capsule it might make an interesting Mid/Side mic, for full range, low noise outdoor recordings.
A bit cumbersome though. -- The capsules need to be housed separately, to avoid RF 'birdies' between 2 independently modulated RF oscillators.
Like Doug, I've never come across the Stephens mic before -- that BBC paper you linked to has some interesting notes about it.
I thought the idea of connecting the mic head to the electronics with specific lengths of cable was quite an interesting concept....
So, Stephens and AKG (and maybe others?) 'dipped their toes' into the world of RF mics back in the day, but is seems that only Sennheiser -- and more recently Rode - have ever run with the concept commercially....
Heres a few pics of the Stephens mic and psu ,
https://www.radiomuseum.org/r/stephens_rf_condenser_microphone_c2_od4.htmlTheres a reference to it in John Eargles microphone book , but its a bit hard to find as its in an older edition I think .
The only reference I can find about the AKG is in the BBC documentation , nothing else anywhere .
The M/S shotgun does look interesting alright , Im imagining it on a double bass , shotgun tube pointed up the neck , side capsule pointed at the instrument body , combined back into mono , distance angle height controlling HF/LF balance and null .
below a representation of the shotgun M/S pickup patern on the Bull Fiddle ,
https://www.radiomuseum.org/r/stephens_rf_condenser_microphone_c2_od4.htmlTheres a reference to it in John Eargles microphone book , but its a bit hard to find as its in an older edition I think .
The only reference I can find about the AKG is in the BBC documentation , nothing else anywhere .
The M/S shotgun does look interesting alright , Im imagining it on a double bass , shotgun tube pointed up the neck , side capsule pointed at the instrument body , combined back into mono , distance angle height controlling HF/LF balance and null .
below a representation of the shotgun M/S pickup patern on the Bull Fiddle ,
Attachments
Mics arrived in ,
One has the KS-16 capsule and all smd components , looks modern , Im not sure if its the 416 T or P48 version ,
the other has the KS15-41 capsule and is all through hole , I think its definatly an MKH415T ,
As the outer case is missing the model number is gone ,
I should be able to trace the schematic for the P48 and determine which kind I have .
They appear to be both T12 types ,
One has the KS-16 capsule and all smd components , looks modern , Im not sure if its the 416 T or P48 version ,
the other has the KS15-41 capsule and is all through hole , I think its definatly an MKH415T ,
As the outer case is missing the model number is gone ,
I should be able to trace the schematic for the P48 and determine which kind I have .
They appear to be both T12 types ,
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