Schematic needed:MFA Magus B

[JAMESP123]

Magus

I have totally recapped the whole preamp with very nice silver in oil caps . I will have to try the Modification that you recommend. I am ordering the 6n6p tube today . Thanks.

 

[rwellerson]

And let us know about your results.
Good luck.

PS.: where I wrote PCI in my previous post please read PCB.

[ ]
R.

 

[SKLau]

I install a Pre-Attenuation circuit to reduce the gain. The Magus uses 100K pots for the gain and volume. Use two pairs of resistors, 82K for Rp1 and 10K for Rp2, for the gain and volume. I have more usable steps from 9 to 1 o’clock and the music with better details and texture. I use Shinkoh for Rp1 and Amtrans carbon film for Rp2.

Here is the link to Goldpoint the Pre-Attenuation circuit.
How To Get More Usable Steps

 

[JAMESP123]

Sent an email to Scott Franklin about the mods. He said they used this circuit in MC reference. He recommended a 9k input resistor and a 200k feedback resistor. I have some cheap metal films that I can use to test with. I am going to try the higher and the lower values to see what make me happier. The one thing Scott pointed out was the high gain in the preamp was to get enough gain for a lower output mc cartridge. The other thing he pointed out is that the use of a really high value input resistor would roll off the high frequency response of the preamp. After I figure out the values I will go ahead and purchase some tantalum resistors or some naked Vishay resistors for the finished circuit.

 

[rwellerson]

Did a TubeCad simulation of the R values I used (and keeping the original value parts and voltages) and got the output below (a calculated 102kHz -3dB is not that bad...)

But that could be wrong, what do you think?

[ ]
R.

 

[rwellerson]

And for Scott's sugestion (R1= 9k): a LOT of gain (this is exactly what I didn't like...)
Actually zero NFB, results the same as the original preamp circuit.

 

[rwellerson]

Any news on this?

 

[Jacekjast1]

Hi from Canada!
I hope you get this message from me.
Dzien dobry!
I see that you have schematics for MFA magus b .
Would you be so kind to email this to me, please🙏
jacekjast1@gmail.com
I have a broken C revision of this pre and super heavy modified so hoping that this will make thing easier.
Dziekuje bardzo
Pozdrawiam.

Jacek

 

[Kennyj]

Hello guys , I just got my hands on the magus mfa (board inside has A2 on it ) and was wondering if anyone has the schematic and psu scam. Thanks so much . I know this thread is old .

 

[Kennyj]

Hello guys , I just got my hands on the magus mfa (board inside has A2 on it ) and was wondering if anyone has the schematic and psu scam. Thanks so much . I know this thread is old .

 

[BMeyerhoff]

Sorry Reinhard for not response earlier.
I have emailed the Magus-A1 schematic to you.

Do you have a copy of the Magus MFA a2 schematic? I have problems with mine.

( PI removed)

 

[AllenB]

BMeyerhoff, it may be better for yourself to leave those details for private message.

 

[BMeyerhoff]

BMeyerhoff, it may be better for yourself to leave those details for private message.

How do you private message for him? Thanks, Bill

 

[JAMESP123]

Do you have a copy of the Magus MFA a2 schematic? I have problems with mine.

this will be 95 percent correct

 

[JAMESP123]

 

[BMeyerhoff]

View attachment 1019446

Thanks but I need the A2 version. My power supply is different than this.

Bill

 

[JAMESP123]

Thanks but I need the A2 version. My power supply is different than this.

Bill

https://www.diyaudio.com/community/threads/schematic-needed-mfa-magus-b.77149/page-2

 

[AllenB]

How do you private message

The envelope button by your username at the top of the screen.