What is the best choice for a gain stage in an LCR phono/line preamp circuit? Get those suggestions coming!
Much thanks!
Filip
Much thanks!
Filip
It is the topology that will determine the choice of tubes, not the LCR sticker. First of all: low or high impedance LCR? How will it be driven? Directly or through a transformer? If directly, what kind of circuit will be doing the driving?
Answer these, choose a gain structure and only then start thinking about tube types.
Answer these, choose a gain structure and only then start thinking about tube types.
I have seen 2 approaches: 1 is using a SRPP (mu follower) stage and 2 a penthode
Monday Modify : 600 Ohm LCR EQ Phonostage Part I – Soundaries
LCR Phono Stage
Monday Modify : 600 Ohm LCR EQ Phonostage Part I – Soundaries
LCR Phono Stage
Hi
I am writing some article on Audioreview magazine in Italy about LCR
The first two part are done.
First of all I suggest you the Shishido diagram. It works well. The gain is not so high, around 32-35 dB but the perfromances are fine.
Another solution Is the use of 5965 with same diagram (just to trim the bias point) , this tube has a higher gain of 6922.
Before the writing of article I have done four different proto with different circuits.
ALL are tested on LAB, non simulations, as usual you can find around the world.
The four protos was done with original Tango stuff EQ-2L.
Then I swap to Sowter 1280 who has the two inductors inside with the same value of Tango. And are easy to buy.
In photo the pcb with 1280 and all components for the LCR stage.
It will be a kit soon.
Then I developped a pcb for a full circuit with LCR that now I am working on it to finish and test on lab to write the third part of my article.
The fourth part will be a full trafo LCR with the possibility to work with two types of tube.
In attach the answer, real answer, of a Tango LCR only, following the indication of Tango about the Zsource and Zload
In case I can send other real test.
I am writing some article on Audioreview magazine in Italy about LCR
The first two part are done.
First of all I suggest you the Shishido diagram. It works well. The gain is not so high, around 32-35 dB but the perfromances are fine.
Another solution Is the use of 5965 with same diagram (just to trim the bias point) , this tube has a higher gain of 6922.
Before the writing of article I have done four different proto with different circuits.
ALL are tested on LAB, non simulations, as usual you can find around the world.
The four protos was done with original Tango stuff EQ-2L.
Then I swap to Sowter 1280 who has the two inductors inside with the same value of Tango. And are easy to buy.
In photo the pcb with 1280 and all components for the LCR stage.
It will be a kit soon.
Then I developped a pcb for a full circuit with LCR that now I am working on it to finish and test on lab to write the third part of my article.
The fourth part will be a full trafo LCR with the possibility to work with two types of tube.
In attach the answer, real answer, of a Tango LCR only, following the indication of Tango about the Zsource and Zload
In case I can send other real test.
Attachments
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The Riaa test I use is done by Audio Precision ( I have two Audio Precision in my lab, Sys One and Sys Two) and it is perfect.
Because it was wrote by software.
So I can use both 20 ohm and 600 ohm without any change on frequency answer; in some case I have adapted the Zsource for different test
In attach the table.
Walter
Because it was wrote by software.
So I can use both 20 ohm and 600 ohm without any change on frequency answer; in some case I have adapted the Zsource for different test
In attach the table.
Walter
Attachments
Last edited:
Gentlemen, i highly appreciate your input.
I am evaluating the findings and accidentally i saw the soundaries attachment which uses the D3A, which i have in abundance. The tubes are going to be transformer coupled, and i would like to apply a 600ohm output. Only trouble is to find the Tango units.
Much thanks to both!
cheers, filip
I am evaluating the findings and accidentally i saw the soundaries attachment which uses the D3A, which i have in abundance. The tubes are going to be transformer coupled, and i would like to apply a 600ohm output. Only trouble is to find the Tango units.
Much thanks to both!
cheers, filip
Very very interesting, please feel free to let me know when the kit becomes available and a link to the review you are writing, grazie mille 🙂
Several (built in or only chokes) equivalents are usable: Silk (SAC Thailand), Sowter, Lundahl, Slagle (intactaudio), Hashimoto, Roehrentechnik ( LCR-RIAA) ... etc.
Acoustic Dimension looked like a good option: passive RIAA LCR unit
But now I see no longer available. Anyway maybe still interesting to look at
Also maybe here silvercore.de
But now I see no longer available. Anyway maybe still interesting to look at
Also maybe here silvercore.de
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Silvercore some years ago discontinued LCR module sales for DIY.
But sales phono box for 6k EUR. 😛
silvercore “phono two” | silvercore.de
But sales phono box for 6k EUR. 😛
silvercore “phono two” | silvercore.de
Look also here
LCR phono stage
There are a real measurements that are impossible to find ( as I know)
Walter
LCR phono stage
There are a real measurements that are impossible to find ( as I know)
Walter
As has already been stated, get the "ducks" lined up and then chose the tube(s) that get used.
For phono preamp duty, the 6GK5 offers an attractive combination of high μ, high gm, and low RP. If a pentode I/P (to eliminate CMiller interaction possibilities) is being considered, look at the 6AC7. High gm will help in counterbalancing partition noise.
For phono preamp duty, the 6GK5 offers an attractive combination of high μ, high gm, and low RP. If a pentode I/P (to eliminate CMiller interaction possibilities) is being considered, look at the 6AC7. High gm will help in counterbalancing partition noise.
I don't know, not tested it.
Maybe contains iron powder pot core chokes (the price is surprisingly low).
The "serious" products built with laminated cores, the very expensive ones contains nickel, amorphous or nano crystalline core materials.
Maybe contains iron powder pot core chokes (the price is surprisingly low).
The "serious" products built with laminated cores, the very expensive ones contains nickel, amorphous or nano crystalline core materials.