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Old 11th May 2021, 06:12 AM   #441
apelizzo is offline apelizzo  Australia
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Originally Posted by stenak View Post
I read an article somewhere on the internet, with a phonoamp project with the D3a tube. Thought that the schematic was a little "messy", with three resistors on the schematic and only two of the mentioned on the drawing. Also found, probably, an old schematic of the same phonoamp, with fewer resistors and capacitors. Anybody outthere who built thisphonoamp?
Hi Stenak, I built that phono preamp a while ago when the thread was active.
I still have to compare it to another one. I am making the N@im phono stage atm. What would you like to know?
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Old 11th May 2021, 06:33 AM   #442
stenak is offline stenak  Norway
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Hi. Thanks for answering! I found two different schematics on the internett, the one found early in this thread, and another one by Ciuffoli, maybe an earlier curcuit?, see link!. I think the schematic of the one Quanghao is a little bit "messy"? Three resistors and on the drawing marked 2 x 47K? Just ordred D3a tubes and I will use p2p soldering, not pcb. My question is: Is the schematic from the link Ok? Much easier to use if you are p2p soldering?
Hi-end phono preamplifier
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Old 11th May 2021, 01:06 PM   #443
apelizzo is offline apelizzo  Australia
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Quote:
Originally Posted by stenak View Post
Hi. Thanks for answering! I found two different schematics on the internett, the one found early in this thread, and another one by Ciuffoli, maybe an earlier curcuit?, see link!. I think the schematic of the one Quanghao is a little bit "messy"? Three resistors and on the drawing marked 2 x 47K? Just ordred D3a tubes and I will use p2p soldering, not pcb. My question is: Is the schematic from the link Ok? Much easier to use if you are p2p soldering?
Hi-end phono preamplifier
Hi Stenak,
The circuit on the webpage you posted uses different setup and lately changed to use smaller mica capacitors.
I have done mine according to the latest design (see attachments).

Cheers
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Old 11th May 2021, 01:22 PM   #444
apelizzo is offline apelizzo  Australia
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Default Phono stage

Quote:
Originally Posted by stenak View Post
Hi. Thanks for answering! I found two different schematics on the internett, the one found early in this thread, and another one by Ciuffoli, maybe an earlier curcuit?, see link!. I think the schematic of the one Quanghao is a little bit "messy"? Three resistors and on the drawing marked 2 x 47K? Just ordred D3a tubes and I will use p2p soldering, not pcb. My question is: Is the schematic from the link Ok? Much easier to use if you are p2p soldering?
Hi-end phono preamplifier
Stenak,
The use of resistors in parallel and in opposite orientation it's Ciuffoli's style. Probably he's got radio engineering background where two identical resistor are connected in parallel with opposite orientation to cancel residual inductance. In audio it's a little overkill but that's his style.

Don't worry if you see three resistor in parallel on the schematic. I think those reflect the positions available on the PCB to give flexibility with paralleling different values. Just follow the text. If you see 2 x 47K it means 1 x 23.5K 2 x 47K or 3 x 15.6K parallel and so on, regardless the number of resistors on the schematic.

With regards to p2p vs PCB, I think for phono stage I would prefer PCB. With p2p you could pickup some noise. The PCB is easy to do. Just use Osmond PCB on MAC (I use Mac) and then upload the gerber files on Fusion PCB Manufacturing & Prototype PCB Assembly - Seeed Studio and you will have it in 1-2 weeks.

Let me know if you need more information.

Last edited by apelizzo; 11th May 2021 at 01:28 PM.
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