12AX7 MM/MC Phono Preamplifier PCB ref VTL

geek_83 · 9th July 2011, 12:53 PM

Hi
I wont to build this project http://analogmetric.com/download/12A...0Schematic.pdf

Manual http://analogmetric.com/download/12A...r%20Manual.pdf

I have two problems:
1) value of the C6 is different in the schematic and BOM - what should it bee 0,01uF or 0,22uF
2) I need help with capacitor picking,i wont to give fallowing capacitors:
C8 and C9 Russian oil cap
C6 Wima black or Russian teflon
C1 Russian oil cap
C3 ordinary Red Wima

What do You Think, what other capacitors would be better ??
I have about 50-80$ for those capacitors.

THX for any help.

analog_sa · 9th July 2011, 01:15 PM

C6 is not very critical but 10nF seems a bit low. 100-200nF will be fine.

Why would you want to build such an old fashioned Marantz 7 clone? Nostalgia?

geek_83 · 9th July 2011, 01:25 PM

No

this project seems to bee pretty decent so i have decide to build it but if You know any better tube pre-amplifier support MC cartridges please insert schematic.

geek_83 · 9th July 2011, 09:03 PM

Quote:

Originally Posted by geek_83

No

this project seems to bee pretty decent so i have decide to build it but if You know any better tube pre-amplifier support MC cartridges please insert schematic.

One mistake MM catridges
And what do you thing about idea of using Russian oil capacitors ?

Mr. dB · 10th July 2011, 04:50 AM

If you're using MM cartridge you'll want to eliminate the grounded-grid input stage and go straight into the second tube.

sugarn · 12th July 2011, 12:30 PM

I have built using this schematic 3 years ago. The value of C6 I use is 0.01uf. I purchase pcb board from Hong Kong (China made). It's modified from VTL ulitimate , not Marantz 7.
It sounds excellent, I love it and still use it until now.

SY · 12th July 2011, 12:39 PM

Take a look at the Marantz 7, then see where VTL's circuit originated.

sugarn · 12th July 2011, 01:14 PM

VTL version is very different from Marantz 7. They both use 3 12AX7 stages but other than that it's not the same and the most important thing they sound different.
Schematic of Marantz 7 phono.
http://www.kitsparts.com/shop/downlo...pdf/M7_Sch.pdf

analog_sa · 12th July 2011, 01:55 PM

What makes you think the circuit in the link is a Marantz 7? Looks like a free interpretation by another kit seller. Passive riaa???

SY · 12th July 2011, 01:59 PM

What analog_sa said. That's not even vaguely a Marantz 7 schematic.

9th July 2011, 12:53 PM	#1
geek_83 diyAudio Member Join Date: May 2007	12AX7 MM/MC Phono Preamplifier PCB ref VTL Hi I wont to build this project http://analogmetric.com/download/12A...0Schematic.pdf Manual http://analogmetric.com/download/12A...r%20Manual.pdf I have two problems: 1) value of the C6 is different in the schematic and BOM - what should it bee 0,01uF or 0,22uF 2) I need help with capacitor picking,i wont to give fallowing capacitors: C8 and C9 Russian oil cap C6 Wima black or Russian teflon C1 Russian oil cap C3 ordinary Red Wima What do You Think, what other capacitors would be better ?? I have about 50-80$ for those capacitors. THX for any help.

12th July 2011, 12:39 PM	#7
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Take a look at the Marantz 7, then see where VTL's circuit originated. __________________ If there's a sucker born every minute, where do the rest of them come from?

12th July 2011, 01:59 PM	#10
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	What analog_sa said. That's not even vaguely a Marantz 7 schematic. __________________ If there's a sucker born every minute, where do the rest of them come from?

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9th July 2011, 01:15 PM	#2
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	C6 is not very critical but 10nF seems a bit low. 100-200nF will be fine. Why would you want to build such an old fashioned Marantz 7 clone? Nostalgia?

9th July 2011, 01:25 PM	#3
geek_83 diyAudio Member Join Date: May 2007	No this project seems to bee pretty decent so i have decide to build it but if You know any better tube pre-amplifier support MC cartridges please insert schematic.

10th July 2011, 04:50 AM	#5
Mr. dB diyAudio Member Join Date: Dec 2003 Location: Arkansas	If you're using MM cartridge you'll want to eliminate the grounded-grid input stage and go straight into the second tube.

12th July 2011, 12:30 PM	#6
sugarn diyAudio Member Join Date: Jun 2004 Location: Bangkok	I have built using this schematic 3 years ago. The value of C6 I use is 0.01uf. I purchase pcb board from Hong Kong (China made). It's modified from VTL ulitimate , not Marantz 7. It sounds excellent, I love it and still use it until now.

12th July 2011, 01:14 PM	#8
sugarn diyAudio Member Join Date: Jun 2004 Location: Bangkok	VTL version is very different from Marantz 7. They both use 3 12AX7 stages but other than that it's not the same and the most important thing they sound different. Schematic of Marantz 7 phono. http://www.kitsparts.com/shop/downlo...pdf/M7_Sch.pdf

12th July 2011, 01:55 PM	#9
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	What makes you think the circuit in the link is a Marantz 7? Looks like a free interpretation by another kit seller. Passive riaa???

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