t. bone SC1100 aka Feilo Z3300 modding, anyone?

[Emmathom]

Thank you for this new SC1100 schem.

A few remarks and questions :

* do we keep the 47uH + 47Ω +10nF as in the original schem ? (see pict)

* do you advise C4-10pF & C5-33pF or C4-33pF & C5-100pF (for unity gain with 33pF and -12dB with 100pF // ) ? If I guess right C4-10pF = +3dB vs C4-33pF = 0db (COG are tough to solder (for me) so I'll go with silver mica)

* I'll measure current drawn by the DC/DC board by inserting a 1KΩ before the board to measure voltage across it and let you know

* my DC/DC board provides +57v / -57v polar. voltages (datas saved from last mods)

BR

 

[Voyager10]

So in your sim, what was the current down the R3/R2/T1/T2/R1 chain? (And, if you have it, the supply voltage, and T2's drain-source voltage).

In a real-life build I guess you'd set the FET currents by adjusting R1, and this will then set the voltage at T1's drain/T3's base.

 

[thor.zmt]

Thank you for this new SC1100 schem.

A few remarks and questions :

* do we keep the 47uH + 47Ω +10nF as in the original schem ? (see pict)

You can, it may be excessive but modern environments have a lot of RF Noise.

* do you advise C4-10pF & C5-33pF or C4-33pF & C5-100pF (for unity gain with 33pF and -12dB with 100pF // ) ? If I guess right C4-10pF = +3dB vs C4-33pF = 0db (COG are tough to solder (for me) so I'll go with silver mica)

Depends on the gain you need/want.

Thor

 

[thor.zmt]

So in your sim, what was the current down the R3/R2/T1/T2/R1 chain? (And, if you have it, the supply voltage, and T2's drain-source voltage).

In a real-life build I guess you'd set the FET currents by adjusting R1, and this will then set the voltage at T1's drain/T3's base.

The two cases @Emmathom suggested the current in T2 was around 0.22mA average between the two. So no adjustment needed.

My sim has 2mA for the bias board.

Thor

 

[Emmathom]

@thor.zmt
no coupling cap between capsule and J113 (K170 sorry) gate ? (I know you will answer that a capsule is already a cap )

 

[thor.zmt]

I know you will answer that a capsule is already a cap )

Correct. Any unnecessary and superfluous parts never improve sound quality.

 

[Voyager10]

And removing the second 1G resistor will reduce noise, in a both measurable and audible way.

 

[Emmathom]

Components for SC110 mod. ordered. Waiting to be delivered in a couple of days. Will begin this project in August.
To be continued...

 

[MicMaven]

Any unnecessary and superfluous parts never improve sound quality.

Ahem ... you sound like Mad Man Muntz ... although you never Muntz your words!

James

 

[thor.zmt]

Ahem ... you sound like Mad Man Muntz ...

I learned from the best.

although you never Muntz your words!

Yup, my teachers name was Ivan. Some called him Terrible...

Thor

 

[Emmathom]

Hi Folks
I'm about to build @thor.zmt SC1100 version and I'd like to get your opinion on transistors I chose at random and measured. Do they suit the circuit ?

K170 (only 2 available)
IDSS 9,3mA / Id 0,54mA / @Vg 375mA
IDSS 9,4mA / Id 0,55mA / @Vg 377mV

J111 (10 available for choice)
IDSS 46mA / Id 4,5mA / @Vg 3,1v

BC559C (50 available for choice)
hFE 463 / Ie 2,6mA / Vbe 646mV
(current displayed by E-152 is 1,5mA)

MPF102 - 10 available (2 choosen at random)
IDSS 7,3mA / Id 0,55mA / @Vg 378mV
IDSS 9,2mA / Id 0,63mA / @Vg 436mV

 

[thor.zmt]

I'm about to build @thor.zmt SC1100 version and I'd like to get your opinion on transistors I chose at random and measured. Do they suit the circuit ?

This was based strictly on using 2SK170 which is already present, as "charge amp".

Thor

 

[Emmathom]

This was based strictly on using 2SK170 which is already present, as "charge amp".

Thor

Ok but what about the values I posted ???
Can I use these tr without any trouble ?
We need 1*SK170 + 1*J111 + 1*BC559C in this circuit...
Do I must understand that J111 & BC559 values don't matter ?
BR

 

[thor.zmt]

Ok but what about the values I posted ???
Can I use these tr without any trouble ?

Yes.

We need 1*SK170 + 1*J111 + 1*BC559C in this circuit...
Do I must understand that J111 & BC559 values don't matter ?

Pretty much so. The J111 should have the highest possible pinch-off voltage, IF there is a choice.

BC559(C) just means "generic high beta PNP Transistor with > 40V Vcbo".

There are many PNP transistors that will work. A suitable low noise, low capacitance P-Channel FET (e.g. BSS84 put on a small adaptor PCB to make a TO-92 style) could also be used.

Thor

 

[Emmathom]

Pretty much so. The J111 should have the highest possible pinch-off voltage, IF there is a choice.

Choice among 10 but they have all very closed same values ...

 

[Emmathom]

This was based strictly on using 2SK170 which is already present, as "charge amp".

Thor

I intend to keep the original-mod. SC1100 boards for the moment and build 2 new boards from scratch. I have four more SK170 in stock and also other Jfets like J304 / J305 / MPF102... (in case of you'd like another ref.)

 

[Emmathom]

Before changing the "original" circuit for the one from @thor.zmt I thought first of all to exchange the original capsule for an Arienne K47 flat and thus compare the 2 microphones with the same circuits.
However, the Arienne does not fix in the t.bone capsule holder : does someone has a link to a support compatible with Arienne K47 flat please?
BR

Edit : problem solved. Soon will come some comparative test (again !) between the 2 capsules with the same circuit.
I know I post "lot of tests" but as a user I'd be grateful to be able to compare things with my own ears so I will go on

 

[Emmathom]

Good shot Buddy ! Hiha !

So asap audio tests :

1) the two mics SC1100 original circuit : original capsule vs Arienne K47flat (to compare the capsules)

2) SC1100 mod. circuit + original capsule vs SC1100 original circuit + original capsule (to compare the circuits)

3) SC1100 mod. circuit + Arienne K47flat vs SC1100 original circuit + original capsule (to compare the two different mics knowing that one is 100% original and the other 100% mod.)

 

[Emmathom]

So today I installed and tested an Arienne K47 flat capsule from @soliloqueen in one of the 2 t.bone SC1100, the other mic having its original capsule.
The circuits are the original ones and have not yet received the circuit designed by @thor.zmt.

I have recorded my voice and only listened to it with headphones for now and I can hear nuances between the 2 capsules. Nuances, not a day vs night difference.

Yes the original SC1100 is a little brighter. The Arienne has less gain and is more balanced and the mediums are more interesting.

An acoustic guitar sample will be soon posted...

24-48 voiceover audio files :
SC1100 original
SC1100 Arienne K47 Flat

Next, after recording an acoustic guitar in this configuration, I'll install the new circuit (J111 + K170 + BC559C)

 

[rock soderstrom]

Yes the original SC1100 is a little brighter.

Yes, I agree, the S sounds are a bit more accentuated but not bad in general. The differences are smaller (in this example) than I expected. I'm looking forward to the acoustic guitar sample...

Which capsule does thomann use in the SC1100? Photo?