MF Citation12 - MF gate resistor value

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi,

I have built recently one channel of MF Citation 12 (quasi complementary version) and it sounds great.

I want to build now the complementary version using IRFP240/IRFP9240 pair. I have seen on many posts overhere that it is recommended to put a 240R resistor on this type of Mosfet. Refering to Mr. Nelson Pass original schematic (see attached pisture) must I change R18 & R19 from 680R to 240R?

Thanks for your help,
 

Attachments

  • MF Citation12_Complementary.JPG
    MF Citation12_Complementary.JPG
    144.3 KB · Views: 244
Refering to Mr. Nelson Pass original schematic (see attached pisture) must I change R18 & R19 from 680R to 240R?

Thanks for your help,
It will definitely sound better with the smaller resistor.

If you have a scope you could try even lower.

You could probably try as low as 100 ohms.

The resistors should be as close to the gate as possible (eg soldered directly to it).
 
Last edited:
Hi NP,

I am completly "stoned" by the sound produced by this simple, rugged, 7-transistors design. It works like a charm at the first power up. I will try with lower Gate resistance values.

In the quasi complementary version I have implemented Gate resistors in the Gate of IRFP240 (see picture attached).

My question: Must I short R18 or leave it like this?

Thanks for your help,
 

Attachments

  • MF Citation 12_Quasi complementary.jpg
    MF Citation 12_Quasi complementary.jpg
    113.9 KB · Views: 200
Yes Tekko go on.

OK Thanh I will report back after completing and listening to the complementary version. Be patient it can be very quick or it can take time :eek:

No answer for my question in post #5?:confused:

No rush. I am a very patient person.
Regarding post 5. I would wait for Nelson on that one.
I found it interesting that the Nelson's quasi version has only the one gate resistor but the complimentary version has two gate resistors.
Could you explain that one Nelson?

Pull that 680 Ohm resistor out and replace it with the smaller valued one.
I would leave it in the same position.

Hopefully Nelson can explain the reason why the other mosfet does not have a gate resistor in his circuit diagram.
 
Hi Nelson,

From your paper D1 is there to make clipping more symmetrical. If I remove it and in the same time make R18 = 0R there will be no blue smoke coming from my circuit right?:eek:

I had also the idea to make R18 = 120R, Rg = 120R (to have 240R in the gate circuit of the IRFP240) and keep D1 in its position. Is this mid-way solution better ?

Thanks for your info
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.