Vacuum State RTP3D preamp

theophile

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theophile

Well-Known Member
Yes Bruce. Thank you for posting that link.
 
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Jaytor

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Dec 22, 2020
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An interesting thread at another forum:

Thanks for linking my thread on SHF. I am planning to share details of my build on WBF once I finish it, but that will probably be several months from now. Unfortunately, I don't have a lot of spare time to work on it.
 

theophile

Well-Known Member
Thanks for linking my thread on SHF. I am planning to share details of my build on WBF once I finish it, but that will probably be several months from now. Unfortunately, I don't have a lot of spare time to work on it.
You're welcome. I have been following your build at SHF. My wonderful memories of Allen draw me to any mention, praise or interest in his legacy. I'd love to hear one of these no holds barred iterations of his designs.
 

Socrates

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Mar 21, 2017
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Hello,

I own a vacuum state RTP3D. But i do not have the schematics. Can anyone provide me the schematics?
 

Socrates

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Mar 21, 2017
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This is quite some project. Congratulations. I was one of the original 10 beta-testers for Allen. It took us about 2 years to build the RTP-3C. I later bought an RTC-3D from Allen, which was built on PCBs. I have been using my prototype RTP-3C as a platform for experimentation. It is now serving as my tape head preamp after I changed the RIAA EQ to tape EQ. My experimentation with different coupling caps led me to use the Wima FKP4. This is a metallized polypropylene film and foil capacitor, designed for pulse applications. It is completely transparent, uncolored and super fast. I don't believe in using caps to "season" the sound. I just want them to get out of the way. I also changed the series type stepped attenuators to a ladder type with constant input impedance. Allen always warned against using other types of attenuators, because a constant 50k input resistance is needed for the RIAA network. I have found a 48-step attenuator using precision resistors that have a pretty much constant input impedance. At least, it does not make enough of a difference that I can detect. The transistor at the phono input stage cascode has been upgraded to MAT2. The RTP-3D uses a different transistor. The power supply capacitors were electrolytic initially, but now, only metallized polypropylene caps are used. I am also using only Lemo Redel sockets and plugs that Allen favored. Even though I don't have a lot of experience with commercial high end preamps, I must say that the RTP-3C/3D is extremely fast, uncolored, detailed and dynamic.
Hello, Can you help me out? I would like to have the schematics. I own a vacuum state RTP3D. I contacted vacuum state but there is no response...
 

Socrates

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Mar 21, 2017
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No, it's not Pat Kennedy.
Person building it is a highly qualified technician /engineer and is intimately familiar with Vacuum State RTP3D, so I have my full confidence in the process
We also upgrading critical caps to V-cap CuFT's
Can you help me out? I am looking for the schematics. I own a rtp3d...
 

Jaytor

Well-Known Member
Dec 22, 2020
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Hello,

I own a vacuum state RTP3D. But i do not have the schematics. Can anyone provide me the schematics?
I think there may be more than one version, but this should be close for the line stage. I don't think the phono stage changed from the RTP3C.

DLT5x88-5A-sch_Rev.jpg
 

DasguteOhr

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Sep 26, 2013
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I think there may be more than one version, but this should be close for the line stage. I don't think the phono stage changed from the RTP3C.

View attachment 122980
Don't forget the tube heating or you get a Ufk problem with the circuit. The voltage difference between the cathode and the tube heater (DC) should not exceed 100volts(ecc88)Tube v4-v5. The only thing that helps is to increase the DC heating voltage. All you need is two resistors (2watt type) and a 10uf electrolytic capacitor. If you don't pay attention, you'll have to change the tubes very quickly - frustration is inevitable.
Shematics and formula

quicklatex.com-054e67c09816e6c65002ba07182a2dc9_l3.png

20240107_080215.jpg
 
Last edited:

adrianywu

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Nov 15, 2021
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Hello, Can you help me out? I would like to have the schematics. I own a vacuum state RTP3D. I contacted vacuum state but there is no response...
I only have the schematics for the RTP 3C.
 

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Jaytor

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Dec 22, 2020
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I only have the schematics for the RTP 3C.
This is the same schematic that I posted, which I believe is the RTP3D. The RTP3C schematic was available on the Vacuum State website for a long time (although doesn't appear to be working now) and is a bit different. The main differences are: The RTP3C uses a single current source for the input stage and uses a negative bias supply for the cathode follower stage CCS. I've included it below.

rtp3c_s.gif
 

adrianywu

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Nov 15, 2021
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This is the same schematic that I posted, which I believe is the RTP3D. The RTP3C schematic was available on the Vacuum State website for a long time (although doesn't appear to be working now) and is a bit different. The main differences are: The RTP3C uses a single current source for the input stage and uses a negative bias supply for the cathode follower stage CCS. I've included it below.

View attachment 123086
The schematic I posted comes from the instruction manual to build the "beta test" version of the RTP-3C. There were 10 of us building this prototype. There were further changes, but minor, after the prototypes were built.
 

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