Macura dispre with mosfet power follower?

sopapo · 6th May 2006, 01:52 PM

Hello,I wonder if the dis pre is a right match for the mosfet power follower...

I am very intrigued for the sound of a power follower....

Have someone try it?

Thanks for all
Best regards

sopapo · 6th May 2006, 03:40 PM

and how to implement a volume pot inm the macura dis pre?

Thanks to all

PMA · 6th May 2006, 05:34 PM

Hello sopapo,

this should work fine together. Regarding volume pot - please see the 1st image on this page:

http://web.telecom.cz/macura/dispre_en.html

The volume pot, preferably low impedance like 10k or 5k, is just at the input of the preamp circuit.

There was a number of people who have built a power follower, maybe if you perform search you may find some posts for example here:
Mosfet power follower (Pavel Macura)

Have a fun with these circuits.

Best regards,

Pavel Macura

PMA · 6th May 2006, 06:22 PM

Regarding Dispre - I have built and sold 15 units, as assembled PCBs. Here you can see the casework implementation of one of my customers:

http://audio.kvalitne.cz/dispre/dispre.htm

Onvinyl · 6th May 2006, 06:58 PM

Hi Pavel,
what I like in your design is the use of those 0,02 EUR Transistors.
I see that you don't use LEDs in the current sources (Q4/Q7) Does it sound better with R15/R18, are there additional reasons? Same question goes for the FC (Q3/R38/R42)
Did you try to use seperate Voltage reg's for the two stages (left and right from R44/C11)?
thanks in advance,
Rüdiger

PMA · 6th May 2006, 07:10 PM

Hi Rüdiger,

in case of this preamp I decided to make it fast and very simple. There was no special intent how to design the current sources. For the reason of their solution and for the reason you mentioned, this preamp needs a decent, very low ripple power supply. C11 and C14 are pretty big, 1000uF. There is also an image with component values on the web page.

Regards,
Pavel

darkfenriz · 6th May 2006, 10:30 PM

Pavel
Why do you use BD139/140 for output stage? Aren't they a bit old?

PMA · 6th May 2006, 10:46 PM

Hi darkfenriz,

you are right, they are old and it would be possible to find better devices. 139/140 are just easy to get and cheap. I may try 15030/15031, but am not able to promise when.

Regards,
Pavel

pinkmouse · 8th May 2006, 01:05 AM

No, he's not banned, he can post any time he wants. But the new user name he came up with above, (no, I wasn't fooled), is now blocked.

PMA · 8th May 2006, 07:37 AM

The fact that another member wrote from the computer at my facility does not mean that I have 2 user names. I also write my posts from at least 2 different IP addresses. Do not block OPA2, there is no reason to do so.

6th May 2006, 01:52 PM	#1
sopapo diyAudio Member Join Date: May 2005 Location: segovia	Macura dispre with mosfet power follower? Hello,I wonder if the dis pre is a right match for the mosfet power follower... I am very intrigued for the sound of a power follower.... Have someone try it? Thanks for all Best regards

6th May 2006, 06:58 PM	#5
Onvinyl diyAudio Member Join Date: Aug 2002 Location: Germany	Hi Pavel, what I like in your design is the use of those 0,02 EUR Transistors. I see that you don't use LEDs in the current sources (Q4/Q7) Does it sound better with R15/R18, are there additional reasons? Same question goes for the FC (Q3/R38/R42) Did you try to use seperate Voltage reg's for the two stages (left and right from R44/C11)? thanks in advance, Rüdiger __________________ "I can feel what's going on inside a piece of electronic equipment. I have a sense that I know what's going on inside the transistors." Robert Moog

8th May 2006, 01:05 AM	#9
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	No, he's not banned, he can post any time he wants. But the new user name he came up with above, (no, I wasn't fooled), is now blocked. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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6th May 2006, 03:40 PM	#2
sopapo diyAudio Member Join Date: May 2005 Location: segovia	and how to implement a volume pot inm the macura dis pre? Thanks to all

6th May 2006, 05:34 PM	#3
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Hello sopapo, this should work fine together. Regarding volume pot - please see the 1st image on this page: http://web.telecom.cz/macura/dispre_en.html The volume pot, preferably low impedance like 10k or 5k, is just at the input of the preamp circuit. There was a number of people who have built a power follower, maybe if you perform search you may find some posts for example here: Mosfet power follower (Pavel Macura) Have a fun with these circuits. Best regards, Pavel Macura

6th May 2006, 06:22 PM	#4
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Regarding Dispre - I have built and sold 15 units, as assembled PCBs. Here you can see the casework implementation of one of my customers: http://audio.kvalitne.cz/dispre/dispre.htm

6th May 2006, 07:10 PM	#6
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Hi Rüdiger, in case of this preamp I decided to make it fast and very simple. There was no special intent how to design the current sources. For the reason of their solution and for the reason you mentioned, this preamp needs a decent, very low ripple power supply. C11 and C14 are pretty big, 1000uF. There is also an image with component values on the web page. Regards, Pavel

6th May 2006, 10:30 PM	#7
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	Pavel Why do you use BD139/140 for output stage? Aren't they a bit old?

6th May 2006, 10:46 PM	#8
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Hi darkfenriz, you are right, they are old and it would be possible to find better devices. 139/140 are just easy to get and cheap. I may try 15030/15031, but am not able to promise when. Regards, Pavel

8th May 2006, 07:37 AM	#10
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	The fact that another member wrote from the computer at my facility does not mean that I have 2 user names. I also write my posts from at least 2 different IP addresses. Do not block OPA2, there is no reason to do so.

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