Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kasperbergholt on May 20, 2025, 10:12:14 am

Title: Using a 6Z4 to 6X4 adapter
Post by: kasperbergholt on May 20, 2025, 10:12:14 am: Hello, clever people,

I have a DAC with a Chinese 6Z4 rectifier tube and an ECC88/6DJ8/6922 amplifier tube. The range of Chinese and Russian equivalents for the 6Z4 family is fairly limited compared to the 6X4.

Apparently, the only difference between the two types (6Z4 vs 6X4) is the pin layout.

Initially, I considered modifying the DAC, but I found that an adapter exists which would allow me to use both types of tubes.

This leads to my question: Are there any theoretical or practical concerns that could degrade the sound when using such an adapter in a rectifier tube position?

Thanks in advance,
Kasper
Title: Re: Using a 6Z4 to 6X4 adapter
Post by: scstill on May 20, 2025, 06:10:29 pm: There is a 5pin 6Z4/84 tube (from the 30's) that evolved into the 7pin 6X4 (40's) and then apparently China made a 7pin tube and used the same 6Z4 designation as the 5pin (confusing). I suppose the 84 designation helps.
Follow successor link at this site for history...https://www.radiomuseum.org/tubes/tube_6z4.html

The great sounding Phirty6 design https://stillampd.com/phirty6 uses the 5pin 6Z4/84 rectifier as it was part of the original car radio. As well, old tubes are also pretty cool...

Should not be any degradation with the adapter you mention
https://www.thetubestore.com/6x4-to-6z4-tube-adapter?srsltid=AfmBOooekfPbkR1rclgu-sveEoCeQZ1xrBTthIOiqo42fdAdUe85sWVv
Title: Re: Using a 6Z4 to 6X4 adapter
Post by: Willabe on May 21, 2025, 06:59:47 am: What is a DAC?
Title: Re: Using a 6Z4 to 6X4 adapter
Post by: scstill on May 21, 2025, 10:34:37 am: maybe something like this
https://www.amazon.com/FLYINSKY-Audiophile-Architecture-Digital-Analog-Converters/dp/B0CZ46JXDZ
Title: Re: Using a 6Z4 to 6X4 adapter
Post by: kasperbergholt on May 21, 2025, 11:58:31 am: Quote from: scstill on May 20, 2025, 06:10:29 pm

There is a 5pin 6Z4/84 tube (from the 30's) that evolved into the 7pin 6X4 (40's) and then apparently China made a 7pin tube and used the same 6Z4 designation as the 5pin (confusing). I suppose the 84 designation helps.

Follow successor link at this site for history...https://www.radiomuseum.org/tubes/tube_6z4.html

Should not be any degradation with the adapter you mention
https://www.thetubestore.com/6x4-to-6z4-tube-adapter?srsltid=AfmBOooekfPbkR1rclgu-sveEoCeQZ1xrBTthIOiqo42fdAdUe85sWVv

Thank you for the reply! Yes, very confusing with the naming, and I was close to getting the wrong type.

The Chinese version is on Radiomusem here:
https://www.radiomuseum.org/tubes/tube_6z4p~2.html

And the Russian equivalent here:
https://www.radiomuseum.org/tubes/tube_6z4p.html

I'll give the adapter a try and report back with results :)
Title: Re: Using a 6Z4 to 6X4 adapter
Post by: kasperbergholt on May 21, 2025, 12:04:27 pm: Quote from: Willabe on May 21, 2025, 06:59:47 am
What is a DAC?

It stands for Digital Audio Converter - used for converting a digital signal from a CD player or a USB streamer into a line level signal that can feed a preamplifer or integrated amplifier.

Mine is based around a 6Z4 rectifier tube & and ECC8 amplifier tube. The converter chip is an Analog Devices AD1865 with a with a CS8412 interface chip.