[dthong]

Have you tried any of the Brimar tubes from Langrex?

I'm tempted to try some out, but I'm curious if they will be too similar in voicing to the Mullards I've got. While I can appreciate the strength of the Mullards, I find I prefer the more even-handed sound of Amperex so far.

When I had Brimars, they were similar to the Mullard CV4003s but with a little more air up top, but otherwise very similar. Langrex has some Brimar 13D5s that are worth trying for the price.

 

[AnyDave]

When I had Brimars, they were similar to the Mullard CV4003s but with a little more air up top, but otherwise very similar. Langrex has some Brimar 13D5s that are worth trying for the price.

Yep, those are the exact ones I'm looking at. Might have to snag a pair.

 

[ThanatosVI]

The previous series KT88 STR Blackplates was very well received.
Now TAD released their new series KT88 STR Redbase

https://www.tubeampdoctor.com/kt88-str-redbase-tad-premium-matched?number=RT892

Maybe worth a try for some?

 

[Andykong]

Minor Revision on Cayin HA-6A

Due to supply chain problems, we have to revise our HA-6A Vacuum Tube Headphone Amplifier as follows:

• Rectifier Tube: from RCA 22DE4 to RCA 17AX4GT

HA-6A with 22DE4 and HA-6A with 17AX4GT will offer the same audio performance, and we have made our best effort to maintain a similar sound signature after the revision.

While the 17AX4GT and 22DE4 are functionally equivalent and structurally very similar to each other, they are not compatible tubes. The filament of 22DE4 is 22.4V, therefore the power supply from HA-6A power transformer to the rectifier tube filament (22DE4) is 23V. On the other hand, the filament of 17AX4GT is 17V, we have to revise the corresponding power supply to 17V in order to facilitate an optimized feed to the 17AX4GT. The circuitry of HA-6A remains unchanged, we only changed the parameter (filament voltage) to the rectifier tube. The amplifier will sound almost the same, the minor difference in sound signature is similar to swapping a vacuum tube during tube rolling, which is inevitable.

As always, we have etched the corresponding vacuum tube product code on the top plate of the amplifier. If you notice the V3 and V4 position is marked as 17AX4GT, that means your HA-6A required a pair of 7AX4GT as rectifier tubes, please do not install a 22DE4 vacuum tube as a replacement. Alternatively, if your HA-6A has marked 22DE4 for V3 and V4, please do not install 17AX4GT as a replacement rectifier tube. If you use a 17AX4GT tube on a 22DE4 amplifier, the tube will be over-voltage and damaged very soon. If you use a 22DE4 tube on a 17AX4GT amplifier, the amplification circuit will be under-voltage and downgrade your amplifier significantly.

The 17AX4GT vacuum tube also existed in the form of 17AX4GTA and 17AX4GTB. While they are three different vacuum tubes, all three are fully compatible with HA-6A, you can pick any one out of these three. We quoted 17AX4GT in the user manual because it is the more popular tube among the three.

Last but not least, you don't have to match the rectifier tubes in HA-6A. When one tube is faulty, you can replace one tube only, and keep the other working until it reaches the end of life. You can even use one 17AX4GTA and one 17AX4GTB as the rectifier tubes in HA-6A. If you are looking for a replacement tube, or want to roll the rectifier tube, look for GE, RCA, and TUNG-SOL, they make these tubes at different times.

For the record, HA-3A has changed the rectifier tube to RCA 25AX4GT already (HERE), HA-300MK2 will continue to use 22DE4 in the foreseeable future.

 

[AnyDave]

Minor Revision on Cayin HA-6A

Due to supply chain problems, we have to revise our HA-6A Vacuum Tube Headphone Amplifier as follows:

• Rectifier Tube: from RCA 22DE4 to RCA 17AX4GT

HA-6A with 22DE4 and HA-6A with 17AX4GT will offer the same audio performance, and we have made our best effort to maintain a similar sound signature after the revision.

While the 17AX4GT and 22DE4 are functionally equivalent and structurally very similar to each other, they are not compatible tubes. The filament of 22DE4 is 22.4V, therefore the power supply from HA-6A power transformer to the rectifier tube filament (22DE4) is 23V. On the other hand, the filament of 17AX4GT is 17V, we have to revise the corresponding power supply to 17V in order to facilitate an optimized feed to the 17AX4GT. The circuitry of HA-6A remains unchanged, we only changed the parameter (filament voltage) to the rectifier tube. The amplifier will sound almost the same, the minor difference in sound signature is similar to swapping a vacuum tube during tube rolling, which is inevitable.

As always, we have etched the corresponding vacuum tube product code on the top plate of the amplifier. If you notice the V3 and V4 position is marked as 17AX4GT, that means your HA-6A required a pair of 7AX4GT as rectifier tubes, please do not install a 22DE4 vacuum tube as a replacement. Alternatively, if your HA-6A has marked 22DE4 for V3 and V4, please do not install 17AX4GT as a replacement rectifier tube. If you use a 17AX4GT tube on a 22DE4 amplifier, the tube will be over-voltage and damaged very soon. If you use a 22DE4 tube on a 17AX4GT amplifier, the amplification circuit will be under-voltage and downgrade your amplifier significantly.



The 17AX4GT vacuum tube also existed in the form of 17AX4GTA and 17AX4GTB. While they are three different vacuum tubes, all three are fully compatible with HA-6A, you can pick any one out of these three. We quoted 17AX4GT in the user manual because it is the more popular tube among the three.

Last but not least, you don't have to match the rectifier tubes in HA-6A. When one tube is faulty, you can replace one tube only, and keep the other working until it reaches the end of life. You can even use one 17AX4GTA and one 17AX4GTB as the rectifier tubes in HA-6A. If you are looking for a replacement tube, or want to roll the rectifier tube, look for GE, RCA, and TUNG-SOL, they make these tubes at different times.

Good information. Thanks Andy.

I received one with the 17ax4. I haven't tube rolled yet, but I am going to snag some 17ax4 variants soon and see how it goes.

 

[Michaels1963]

What is the service Life of the 22DE4 tube?

 

[Andykong]

What is the service Life of the 22DE4 tube?

Theoretically, 22DE4 as a rectifier tube has a very long expected life span, they can easily last 5 years of daily use. You don't need to have matched pair with 22DE4. They are meant to isolate the power supply from each other, so each team is working independently, and they will age at a different pace, so you can swap out one tube only instead of changing two tubes at the same time.

 

[jamato8]

What is the service Life of the 22DE4 tube?

I have read 5 to 10 years. So I have enough to last 2 to 3 hundred years. lol

 

[AnyDave]

I have read 5 to 10 years. So I have enough to last 2 to 3 hundred years. lol

Most rectifier tubes are 5,000 to 10,000 hours. So 5-10 years if you listen 3 hours per day. Sometimes tubes fail for inexplicable reasons, but NOS rectifiers are often pretty robust.

 

[jamato8]

Most rectifier tubes are 5,000 to 10,000 hours. So 5-10 years if you listen 3 hours per day. Sometimes tubes fail for inexplicable reasons, but NOS rectifiers are often pretty robust.

Yes, a lot of the old rectifiers are built well and if a cap is used after the rectifier, so as to not draw too much current, and system demands are normal, they last a very long time. I have one metal base GZ34 that has 20 or 30 thousand hours on it. It stills tests as new and sounds superb. But those were made extremely well. The 22DE4 type isn't as robust but I would still imagine they are going to hold up great. And you could always put a very fast solid state rectifier in front of the tube, to do all the grunt work, have the drop of the tube rectifier and the tube sound and further smoothing of the sawtooth wave.

 

[AnyDave]

Yes, a lot of the old rectifiers are built well and if a cap is used after the rectifier, so as to not draw too much current, and system demands are normal, they last a very long time. I have one metal base GZ34 that has 20 or 30 thousand hours on it. It stills tests as new and sounds superb. But those were made extremely well. The 22DE4 type isn't as robust but I would still imagine they are going to hold up great. And you could always put a very fast solid state rectifier in front of the tube, to do all the grunt work, have the drop of the tube rectifier and the tube sound and further smoothing of the sawtooth wave.

Yeah, those GZ34s last forever. I've got a couple in 60's Fender guitar amps that I've never changed.

 

[jamato8]

Yeah, those GZ34s last forever. I've got a couple in 60's Fender guitar amps that I've never changed.

I have a box full of Mullards and Philips and Philips in metal base, all NOS.

But back to the 6A. Great amp, just need to use a fork lift to move it. lol

 

[AnyDave]

I have a box full of Mullards and Philips and Philips in metal base, all NOS.

But back to the 6A. Great amp, just need to use a fork lift to move it. lol

A bit jealous of that GZ34 stash, I must admit.

And year, the 6A is a cool amp. I'm enjoying mine.

 

[suno23]

I have read 5 to 10 years. So I have enough to last 2 to 3 hundred years. lol

when I turn 200 will you sell me one set?

 

[jamato8]

when I turn 200 will you sell me one set?

Glad to, if I can remember where they are.