Re: Schoeps Blue Dot Sensitivity CMC5

[Scott Dorsey]

In article >,
Sean B > wrote:
>Hello,
>
>
>How is the +5dB gain increase produced inside the Schoeps CMC5 body?

With transistors.

Literally, there is a small amount of voltage gain and a massive amount
of current gain from the front end FET.

The output stage is just dual cathode followers, producing only current
gain with no voltage gain.

The current gain is enormous throughout the thing... input Z is several
megohms and output Z is tens of ohms. The voltage gain is minimal.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Phil Allison[_4_]]

Scott Dorsey wrote:

>
> Sean B
> >
> >How is the +5dB gain increase produced inside the Schoeps CMC5 body?
>
> With transistors.
>
> Literally, there is a small amount of voltage gain and a massive amount
> of current gain from the front end FET.
>
> The output stage is just dual cathode followers, producing only current
> gain with no voltage gain.
>

** This U-Tube shows how the adjustment can be done:

https://www.youtube.com/watch?v=xtcnoC620Fc


( Scott mean to say " emitter followers", not cathode )


> The current gain is enormous throughout the thing... input Z is several
> megohms and output Z is tens of ohms. The voltage gain is minimal.


** The front end FET stage would have an input resistance about 1 Gigaohm - hence the warnings about handling that area.



..... Phil

[geoff]

On 4/07/2018 11:03 AM, Phil Allison wrote:
> Scott Dorsey wrote:
>
>>
>> Sean B
>>>
>>> How is the +5dB gain increase produced inside the Schoeps CMC5 body?
>>
>> With transistors.
>>
>> Literally, there is a small amount of voltage gain and a massive amount
>> of current gain from the front end FET.
>>
>> The output stage is just dual cathode followers, producing only current
>> gain with no voltage gain.
>>
>
> ** This U-Tube shows how the adjustment can be done:
>
> https://www.youtube.com/watch?v=xtcnoC620Fc
>
>
> ( Scott mean to say " emitter followers", not cathode )


I was going to say that !

Talking about the 'cathode-world' I got a 450VDC belt two days ago from
a guitar amp I am working on. Thought I had discharged everything, but
obviously hadn't. Yesterday could still feel where it went in my left
thumb, and out my right middle finger ! OK today. Screwdriver in left
hand went for miles !

geoff