Between both tubes, which one do you guys prefer for WOT linestage??
1/2 6H30 => 6K:600R
6GK5 => 30K:600R
1/2 6H30 => 6K:600R
6GK5 => 30K:600R
Too few words. Too many unknowns. By “WOT linestage” do you mean Diego Nardi’s WOT output transformer preamp from Sound Practices #10? If so why do you want to replace the 5687 tube used in that design?
Sorry for misleading! It should be transformer coupled. But I guess the term "With Output Transformer" is the same.
I want to build an Ultrapath type line amp with either tube. Cathode bias would be either low voltage negative regulated or battery.
So the Ultrapath cap would be much smaller than using cathode resistor
I want to build an Ultrapath type line amp with either tube. Cathode bias would be either low voltage negative regulated or battery.
So the Ultrapath cap would be much smaller than using cathode resistor
I'm glad you have mentioned the 5687 WOT and I found the Fluence 5687 WOT.
flupage.htm
As I like 5687 as well, It might be another option with minor modifications for Ultrapath arrangement. 🙂
But I will add one more stage in the power supply for filtering and has gas tube for regulation.
More questions. Have you defined what your requirements are for the linestage and how you plan to use it? Do you need all the gain a 6GK5 could provide? What made you decide on Ultrapath topology? I assume you read up on Ultrapath on the web, for example:
Ultrapath Line Stage
Have you ruled out other topologies? Do you have suitable output transformers already? If not have you considered gyrator-loaded line stages, for example:
26 DHT Preamp Gen3 (Gyrator version) – Bartola(R) Valves
Ultrapath Line Stage
Have you ruled out other topologies? Do you have suitable output transformers already? If not have you considered gyrator-loaded line stages, for example:
26 DHT Preamp Gen3 (Gyrator version) – Bartola(R) Valves
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26 tube is very rare.
Regarding the gain of 6GK5, that's why I choose 30K:600R ratio for the drop.
Regarding the gain of 6GK5, that's why I choose 30K:600R ratio for the drop.
Designing and manufacturing -good- n*10k:600 output transformer is not an easy job, so this type OTs are rare and horribly priced.
Finemet Line Level, Input, Output Audio Transformer / made in JAPAN | eBay
Finemet Line Level, Input, Output Audio Transformer / made in JAPAN | eBay
I have used similar Noguchi line outputs and find them strictly an acquired taste soundwise.
Is input capacitance important to you?
Where will the volume control be?
What kind of volume control will there be?
Where will the volume control be?
What kind of volume control will there be?
I use 20K ladder type stepped attenuator with Sowter 20K:20K input transformer for noise isolation.
Input capacitance of a 6GK5 is fairly high. But a 20k ohm volume control will present a maximum source impedance of only 5k ohms, so that would work and not restrict bandwidth on the high end.
Isn't the rp of a 6GK5 around 5k ohms? Isn't that kind of high for loading the primary of an OPT? What's the primary inductance of the OPT you're thinking of using?
Is it this one?
PRODUCT PAGE
Lpri = 180H
With 5k Zout from the driver tube, F3 would be about 4.5Hz, so I guess that works too.
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Isn't the rp of a 6GK5 around 5k ohms? Isn't that kind of high for loading the primary of an OPT? What's the primary inductance of the OPT you're thinking of using?
Is it this one?
PRODUCT PAGE
Lpri = 180H
With 5k Zout from the driver tube, F3 would be about 4.5Hz, so I guess that works too.
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I am considering between Bartola SF and line output transformer. The transformer ratio is 30K:600R
The impedance ratio is a nominal thing.
The primary inductance defines the low frequency cutoff.
The primary inductance defines the low frequency cutoff.