[busseysound]

Rectifier tube rolling:

Western Electric 422A (gray plate 1953)
Got this legendary rectiifer today and spending my first few hours with it. It is definitely distinct and provides a different sound profile compared to the GZ34 I've had there for the past few months. My initial impressions:

1. Extended lower bass - there is a notable bit of extra extension and resolution at the very lowest reaches of the FR
2. More rounded/sweet/warm sound - neither a plus nor a minus, more of an overall feel of the notes be rounded off; it can be called sweetness, but it's also a bit of the opposite of air; presentation remains very holographic, but timbre is perhaps a bit more saccharine

Philips Miniwatt GZ34 (brown base Sittard factory 1968)
This is my reference point. In comparison, the GZ34 feels more open and resolving in the mids, with a bit more air and openness. They have great bass, but not that extra depth of the 422A. They present a more neutral timbre compared to the 422A warmer presenation.

This presents a great opportunity to roll to mood, overall preference, or depending on the rest of your chain. My impressions will likely also evolve, but sharing my intital take after a few hours of comparison (I'm still using the Tung-Sol 5687 and RCA 6BQ7A when testing the above).

Next - I plan to try the 422A in the Taboo (with the OTL as pre-amp)..

How are you liking the 422A? I'm more and more impressed each day with the WE 724B

 

[goldwerger]

How are you liking the 422A? I'm more and more impressed each day with the WE 724B

It's not for me.. too rounded off... I am back with the GZ34, which I like best so far.

I haven't tried the 274B, and heard great things. I hope to test that one day soon!

 

[fiascogarcia]

It's not for me.. too rounded off... I am back with the GZ34, which I like best so far.

I haven't tried the 274B, and heard great things. I hope to test that one day soon!

I don't know; I'm kind of feeling like the 422 is a little more spacious than the GZ34, to my ears that is. That's using it with the Siemens E88CC input, and Wandla DAC. I'm sure source and other chain differences make a difference in perception as well. Both rectifiers are excellent on the ZMF OTL! Incoming, I'm waiting for some input tubes; the Siemens E88CCa and 6N23P Reflektor Holy Grail 1975 SWGP Silver Shields (that's a mouthfull!).

 

[goldwerger]

I don't know; I'm kind of feeling like the 422 is a little more spacious than the GZ34, to my ears that is. That's using it with the Siemens E88CC input, and Wandla DAC. I'm sure source and other chain differences make a difference in perception as well. Both rectifiers are excellent on the ZMF OTL! Incoming, I'm waiting for some input tubes; the Siemens E88CCa and 6N23P Reflektor Holy Grail 1975 SWGP Silver Shields (that's a mouthfull!).

Synergy with the other tubes can definitely play a role here (as the fact that I have an old 422A)

 

[Traiguen]

How does this amp work with the 60 ohm impedance Caldera??

 

[goldwerger]

How does this amp work with the 60 ohm impedance Caldera??

It works well but no ideal - it actually has the power to drive it (Caldera is reasonably easy to drive) but the damping ratio is too low for my taste, which manifests itself in a slightly more bloaty bass that is less defined and tight.

I generally do not recommend using any OTL for Caldera (or other planar headphones).

The OTL works really well with any dynamic high impedance headphones I tried with it, including the AO, AC, VO ADX5000, and HD800S - for those, this amp is the best I’ve ever heard those headphones, truly magnificent.

 

[Traiguen]

It works well but no ideal - it actually has the power to drive it (Caldera is reasonably easy to drive) but the damping ratio is too low for my taste, which manifests itself in a slightly more bloaty bass that is less defined and tight.

I generally do not recommend using any OTL for Caldera (or other planar headphones).

The OTL works really well with any dynamic high impedance headphones I tried with it, including the AO, AC, VO ADX5000, and HD800S - for those, this amp is the best I’ve ever heard those headphones, truly magnificent.

Have you tried the Pre-Amp on this OTL?

 

[goldwerger]

Have you tried the Pre-Amp on this OTL?

Yes it very good.

I actually user it both as an OTL, and as a preamp to a Decware Taboo power amp (the latter combo being my favorite chain for the Caldera).

I’ve experimented with the OTL as a preamp into a variety of amp. Volume control was excellent in all, and the characters of the tubes rolled had an impact on the chain - so if you enjoy playing with tubes, a definitely plus here.

Note the preamp is RCA out only so plan around those cables on the receive amp side.

 

[Traiguen]

Yes it very good.

I actually user it both as an OTL, and as a preamp to a Decware Taboo power amp (the latter combo being my favorite chain for the Caldera).

I’ve experimented with the OTL as a preamp into a variety of amp. Volume control was excellent in all, and the characters of the tubes rolled had an impact on the chain - so if you enjoy playing with tubes, a definitely plus here.

Note the preamp is RCA out only so plan around those cables on the receive amp side.

Thank you!
I just pulled the trigger on the ZMF Decware OTL. I will use it as a preamp for my Silver Fox with the Caldera and directly into a ZMF Auteur!!!
I hope and can now stop this endless chase of a better sound. (at least for a while...)

 

[goldwerger]

Thank you!
I just pulled the trigger on the ZMF Decware OTL. I will use it as a preamp for my Silver Fox with the Caldera and directly into a ZMF Auteur!!!
I hope and can now stop this endless chase of a better sound. (at least for a while...)

That’s a wonderful plan!

Congrats!

Pls share your impressions when you get it

 

[Traiguen]

Beautiful ZMF Decware OTL is in the house!!!! It will keep company to my Silver Fox as a Pre-Amp and as an amp for my 300 ohms headphones.
I just set it up so I cannot comment much on the sound beyond the first impression of being absolutely sweet, clear, live and engaging besides of being beautiful to look at!
Now it's time to just sit back and enjoy the music. (I wish it was Friday....)

Especial thanks to Zach @zach915m for his help.

 

[goldwerger]

Beautiful ZMF Decware OTL is in the house!!!! It will keep company to my Silver Fox as a Pre-Amp and as an amp for my 300 ohms headphones.
I just set it up so I cannot comment much on the sound beyond the first impression of being absolutely sweet, clear, live and engaging besides of being beautiful to look at!
Now it's time to just sit back and enjoy the music. (I wish it was Friday....)

Especial thanks to Zach @zach915m for his help.

Nice!!!

 

[busseysound]

Beautiful ZMF Decware OTL is in the house!!!! It will keep company to my Silver Fox as a Pre-Amp and as an amp for my 300 ohms headphones.
I just set it up so I cannot comment much on the sound beyond the first impression of being absolutely sweet, clear, live and engaging besides of being beautiful to look at!
Now it's time to just sit back and enjoy the music. (I wish it was Friday....)

Especial thanks to Zach @zach915m for his help.

Congratulations!

 

[Coran]

Well, the past month or so has been spent tube rolling with this wonderful amplifier. I have been rather surprised at the dramatic differences some tubes have, it has been a joy to experiment!

The first swap (aside from using the Emission Labs 5U4G or an Elrog 5U4G) was to slot in my Tung-sol 5687 (once the adapters arrived). Those were a wonderful upgrade to detail, clarity and space.

Next up was swapping between Philips ECG JAN 6922 and the RCA 6BQ7A. I was surprised how much of a difference in sound I heard going between those two little tubes. The Philips was fun and dynamic while the RCA was rather airy and spacious. Curiously the RCA lost a lot of low end and emphasized the highs just a hair above what I like. Although that didn't last long...

After playing with those tubes, the Philips Miniwatt GZ34 arrived in the mail after a lengthy wait. This changed a few things! First, the Philips got even more fun, bassy, and just all around tubey which made for some very fun listening. Such a dramatic change with the rectifier made me interested in the changes with the RCA, so back in it went. My goodness...what joy that was. Absolutely beautiful resolution and holographic soundstage. The bass came back but was perfectly extended and controlled and didn't bleed into the mids. Oh, and the mids? Perfection. That, along with the wonderful detail in the highs made for quite the listen. I feel like my toe was tapping to music in a way that it hasn't done in a while.

After all is said and done, I think I've settled on using the Philips Miniwatt GZ34 along with the Tung-sol 5687 and RCA 6BQ7A. Just pure joy coming out of this amp right now. I loved the Atrium Open before, but this amp really takes them to another level (the AC are also a dream on it). I have some other tubes I want to try, but right now this will do just fine.

 

[goldwerger]

Well, the past month or so has been spent tube rolling with this wonderful amplifier. I have been rather surprised at the dramatic differences some tubes have, it has been a joy to experiment!

The first swap (aside from using the Emission Labs 5U4G or an Elrog 5U4G) was to slot in my Tung-sol 5687 (once the adapters arrived). Those were a wonderful upgrade to detail, clarity and space.

Next up was swapping between Philips ECG JAN 6922 and the RCA 6BQ7A. I was surprised how much of a difference in sound I heard going between those two little tubes. The Philips was fun and dynamic while the RCA was rather airy and spacious. Curiously the RCA lost a lot of low end and emphasized the highs just a hair above what I like. Although that didn't last long...

After playing with those tubes, the Philips Miniwatt GZ34 arrived in the mail after a lengthy wait. This changed a few things! First, the Philips got even more fun, bassy, and just all around tubey which made for some very fun listening. Such a dramatic change with the rectifier made me interested in the changes with the RCA, so back in it went. My goodness...what joy that was. Absolutely beautiful resolution and holographic soundstage. The bass came back but was perfectly extended and controlled and didn't bleed into the mids. Oh, and the mids? Perfection. That, along with the wonderful detail in the highs made for quite the listen. I feel like my toe was tapping to music in a way that it hasn't done in a while.

After all is said and done, I think I've settled on using the Philips Miniwatt GZ34 along with the Tung-sol 5687 and RCA 6BQ7A. Just pure joy coming out of this amp right now. I loved the Atrium Open before, but this amp really takes them to another level (the AC are also a dream on it). I have some other tubes I want to try, but right now this will do just fine.

You ended up with my exact roll, but really enjoyed reading how you got there, very informative. Totally agree, this amp responds quite a bit to each of these tube rolls, and every combination creates a new synergy.

I suspect there may several “combinations” to discover long run. This makes me reflect on my experience with the WE 422A that didn’t make the cut. Perhaps with some entirely new gain and output tubes it may work better. I’ll try that at some point.

Thanks for sharing!