Hi guys,
I want to add a valve DHT output for my noDAC to reach the 2VRMS, attached schematic used.
TIA
Felipe
N.B. using the low pass filter gives 1.1V RMS at full output.
I want to add a valve DHT output for my noDAC to reach the 2VRMS, attached schematic used.
TIA
Felipe
N.B. using the low pass filter gives 1.1V RMS at full output.
Attachments
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For the start, it must definitely be as little microphonic as possible. That excludes the cheap 4P1L.
26 can be enough or it will need a driver?
#26 has -about- 8x amplification factor.
2A3 has about 4x.
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Felipe, i have 2.25Vrms output signal after isolator board and filter.
So i use a cathode follower schematic( 0,95x amp). I use not dht but 6N6P.
So i use a cathode follower schematic( 0,95x amp). I use not dht but 6N6P.
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#26 has -about- 8x amplification factor.
2A3 has about 4x.
Enough 2A3 but expensive.
Felipe, i have 2.25Vrms output signal after isolator board and filter.
So i use a cathode follower schematic( 0,95x amp). I use not dht but 6N6P.
What LPF do you use?
Felipe, i have 2.25Vrms output signal after isolator board and filter.
So i use a cathode follower schematic( 0,95x amp). I use not dht but 6N6P.
What LPF do you use?
Felipe, i have 2.25Vrms output signal after isolator board and filter.
So i use a cathode follower schematic( 0,95x amp). I use not dht but 6N6P.
Used I2S isolator but introduces noise.
#26 has -about- 8x amplification factor.
2A3 has about 4x.
Bela is not too much amplification 4X, do you know another DHT 2X to reach the 2VRMS output?
2A3 is the same like the Russian 6S4S or 6C4C?
What LPF do you use?
See schematic below.
Attachments
71A gain is 3x....
Thank you
See schematic below.
Neat, what's the corner frequency Fc? What's the pourpose of resistor 1.5K?
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Why not isolating transformer 10k/40k (about 40$ a pair on Aliexpress) and cathode follower as 6N1p for example?
I want DHT, yes I'm contemplating also a step up 1:2 transformer without DHT output stage, but I'm lost looking for proper step up transformer?
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Instead of building some half baked DHT output for this very dubious project, why don't you build a no-compromise DHT preamp which will work with the nodac but also work with any future projects too? It will very likely be transformer coupled and this will also take care of filtering >100kHz.
I have one: 26 preamp, but will be great to have the same gain like the Valve Itch phono preamp.
My 26 is choke loaded, I prefer the sound over OPT.
My 26 is choke loaded, I prefer the sound over OPT.
The filter has first corner frequency at about 23khz and second at 64khz. The 1k5 resistance i tune the transformer i had behind the filter.
I will offer 3 ideas.
1: If all you have to do is basically double the voltage, I would just use a step up transformer. A step up transformer is going to do a better job than a tube ever could.
2: If you have to use a tube and it has to be a DHT, I would look into the 300b. Theoretically it could be configured to give you 600 ohms for the output impedance which might have some neat applications.
3: If you want a tube, but would be willing to consider an indirectly heated triode, then a 6as7g might be neat *shrug*
I would just shoot sowter an email. If you show them what you are up to, they can recommend you a decent transformer.
1: If all you have to do is basically double the voltage, I would just use a step up transformer. A step up transformer is going to do a better job than a tube ever could.
2: If you have to use a tube and it has to be a DHT, I would look into the 300b. Theoretically it could be configured to give you 600 ohms for the output impedance which might have some neat applications.
3: If you want a tube, but would be willing to consider an indirectly heated triode, then a 6as7g might be neat *shrug*
I want DHT, yes I'm contemplating also a step up 1:2 transformer without DHT output stage, but I'm lost looking for proper step up transformer?
I would just shoot sowter an email. If you show them what you are up to, they can recommend you a decent transformer.
The filter has first corner frequency at about 23khz and second at 64khz. The 1k5 resistance i tune the transformer i had behind the filter.
I supposed did you used a 4th order low pass filter.
I will offer 3 ideas.
1: If all you have to do is basically double the voltage, I would just use a step up transformer. A step up transformer is going to do a better job than a tube ever could.
2: If you have to use a tube and it has to be a DHT, I would look into the 300b. Theoretically it could be configured to give you 600 ohms for the output impedance which might have some neat applications.
3: If you want a tube, but would be willing to consider an indirectly heated triode, then a 6as7g might be neat *shrug*
1: Interested what I don't want a custom step up transformer to avoid high prices.
2: 300B is a expensive DHT & I guess I didn't need that gain.
3: Used the 6AS7 as output in a headphone amp but I prefer DHT.
I would just shoot sowter an email. If you show them what you are up to, they can recommend you a decent transformer.
See post 19 mine answer 1
The filter has first corner frequency at about 23khz and second at 64khz. The 1k5 resistance i tune the transformer i had behind the filter.
Could you elaborate why you chosen two corner frequencies and what's the final Fc?
choke loaded, I prefer the sound over OPT.
Curiously, so did i. At least while being stuck in the Lundahl swamp 😀
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