Attached are the files for the TMOQ 834P Preamp, released for the benefit of the public. Includes BOM and schematic for the main board, tube power supply and SS Power supply in various flavors.
Also attached is the original version of Thorsten's "The very much non-definitive EAR 834P Modification Guide"
Feel free to use this thread to document your builds.
Some threads for reference:
End Of Life Phonostage / The Last Phonocorrector - Romy The Cat's Thread
EAR 834P Modification Guide 834PTF - Romy The Cat
LencoHeaven 834P TRLH Thread - Lencoheaven
Original 834 Douk Board Thread - Lencoheaven
“The earth cannot move without music. The earth moves in a certain rhythm, a certain sound, a certain note. When the music stops the earth will stop and everything upon it will die.”
― Sun Ra, Space is the Place
Also attached is the original version of Thorsten's "The very much non-definitive EAR 834P Modification Guide"
Feel free to use this thread to document your builds.
Some threads for reference:
End Of Life Phonostage / The Last Phonocorrector - Romy The Cat's Thread
EAR 834P Modification Guide 834PTF - Romy The Cat
LencoHeaven 834P TRLH Thread - Lencoheaven
Original 834 Douk Board Thread - Lencoheaven
“The earth cannot move without music. The earth moves in a certain rhythm, a certain sound, a certain note. When the music stops the earth will stop and everything upon it will die.”
― Sun Ra, Space is the Place
Attachments
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My quick two cents:
RIAA:
In the RIAA section I often combined a 750K and a 40K to get 790K, and a 270pf and a 33pf to get 303pf. That gave the most accurate RIAA curve. I was satisfied with Silver Mica and RN60.
I don't think air gap capacitors are much better than other alternatives. They can cause RF pickup and are a pain in the neck to fit inside a chassis. In my experience, hand-selecting and matching components for precision values yields significantly better results than any one composition or type.
Tubes:
Best results were found with.
V1 - Mesa Boogie selected low-noise 12AX7 for their guitar amps, of all things.
V3 - In modelings the 12AT7 performed the best in the cathode follower position, followed by 12AU7.
I used an old Telefunken EZ81 in the dual PSU.
Getting matched sides of a tube is the name of the game. Paying close attention to grounding and the provisions for the tube cans will yield big dividends. Using the specified tube sockets with the ground post is highly recommended.
PSU:
PSU selection makes a difference, but it's also a matter of space and budget. Good results can be achieved a variety of ways. Make sure you have the space before going down the dual PSU route. I would prefer the single PSU in a separate chassis with an umbilical over the dual PSU in the same chassis.
Cs and Rs:
I try to avoid electrolytics wherever possible, not for sound reasons in most cases as much as when I build something I like to build it for life. A great provision on these boards is for those 30uf Vishay film caps- it would be a shame to use electrolytics in this position given the effort and pcb real estate set aside for them.
I've built this 20 different ways, and I was perfectly satisfied with Vishay RN metal film and wirewound across the board. I liked those old Russian Polystyrene military caps, much more than the film / foil variants or even Teflon, but good results can be found from typical Mouser offerings.
Pay special attention to large caps with metal casings.
SUTs:
I'm a Shure V15 Type III kind of guy at the end of the day, so my experience with SUTs and so forth was minimal while I experimented with a Denon 103R and some others. After all my wanderings, I have come back home to an SP-10, 3009, and a V15 III.
Much of the music I love and cherish sounds like it was recorded on a toaster anyway....
Anyhow, the result will be a phono preamp that sounds to me, and many others, like "the right thing." Of course, this is where the bickering ensues and I bow out, but I don't see how you could be let down by this design if you implement it competently. I don't believe it was by mistake that this design has seen a modification cult following develop around it over the last 20-plus years.
Careful attention to detail, layout, wiring, grounding etc. will be more rewarding than pursuing rarified audio talismans of various kinds. Build it the simple and sane way the first time- don't get led into the abyss.
The important thing is that you have a good time and enjoy the result- don't obsess over the small stuff. Life is short, time is precious.
Godspeed.
RIAA:
In the RIAA section I often combined a 750K and a 40K to get 790K, and a 270pf and a 33pf to get 303pf. That gave the most accurate RIAA curve. I was satisfied with Silver Mica and RN60.
I don't think air gap capacitors are much better than other alternatives. They can cause RF pickup and are a pain in the neck to fit inside a chassis. In my experience, hand-selecting and matching components for precision values yields significantly better results than any one composition or type.
Tubes:
Best results were found with.
V1 - Mesa Boogie selected low-noise 12AX7 for their guitar amps, of all things.
V3 - In modelings the 12AT7 performed the best in the cathode follower position, followed by 12AU7.
I used an old Telefunken EZ81 in the dual PSU.
Getting matched sides of a tube is the name of the game. Paying close attention to grounding and the provisions for the tube cans will yield big dividends. Using the specified tube sockets with the ground post is highly recommended.
PSU:
PSU selection makes a difference, but it's also a matter of space and budget. Good results can be achieved a variety of ways. Make sure you have the space before going down the dual PSU route. I would prefer the single PSU in a separate chassis with an umbilical over the dual PSU in the same chassis.
Cs and Rs:
I try to avoid electrolytics wherever possible, not for sound reasons in most cases as much as when I build something I like to build it for life. A great provision on these boards is for those 30uf Vishay film caps- it would be a shame to use electrolytics in this position given the effort and pcb real estate set aside for them.
I've built this 20 different ways, and I was perfectly satisfied with Vishay RN metal film and wirewound across the board. I liked those old Russian Polystyrene military caps, much more than the film / foil variants or even Teflon, but good results can be found from typical Mouser offerings.
Pay special attention to large caps with metal casings.
SUTs:
I'm a Shure V15 Type III kind of guy at the end of the day, so my experience with SUTs and so forth was minimal while I experimented with a Denon 103R and some others. After all my wanderings, I have come back home to an SP-10, 3009, and a V15 III.
Much of the music I love and cherish sounds like it was recorded on a toaster anyway....
Anyhow, the result will be a phono preamp that sounds to me, and many others, like "the right thing." Of course, this is where the bickering ensues and I bow out, but I don't see how you could be let down by this design if you implement it competently. I don't believe it was by mistake that this design has seen a modification cult following develop around it over the last 20-plus years.
Careful attention to detail, layout, wiring, grounding etc. will be more rewarding than pursuing rarified audio talismans of various kinds. Build it the simple and sane way the first time- don't get led into the abyss.
The important thing is that you have a good time and enjoy the result- don't obsess over the small stuff. Life is short, time is precious.
Godspeed.
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