Philips Miniwatt GZ34 Metal Base made in Holland with a Erik Akerlund & Ruben Rausing box

[robolton]

Just picked this up > Philips Miniwatt GZ34 Metal Base made in Holland with Date Code TV2 57A, it was in a Akerlund & Rausing box. Has anyone seen this before? I have only seen this type of box from only one listing for a Standard Radio & Telefon AB (SRT) 22S22C tube.​

 

[rbbert]

Looks nice. When are you going to see how it sounds?

 

[Cellcbern]

Just picked this up > Philips Miniwatt GZ34 Metal Base made in Holland with Date Code TV2 57A, it was in a Akerlund & Rausing box. Has anyone seen this before? I have only seen this type of box from only one listing for a Standard Radio & Telefon AB (SRT) 22S22C tube.​

Great tube - best 5AR4 ever made - used one in my Modwright PS 9.0 for several years. The only rectifiers I've tried in the PS 9.0 that surpassed it are the rare, expensive U52/5U4G/CV575 (labeled GEC/Osram/Marconi/MWT/Brimar), and Sophia Electric's new Aqua 274B - the only 274B which is a drop-in replacement for a 5U4G.

 

[rbbert]

I suspect it is the same tube as the highly regarded Amperex 1950's metal base?

 

[Cellcbern]

I suspect it is the same tube as the highly regarded Amperex 1950's metal base?

Yes. I've seen this tube labeled Phillips, Amperex, and Mullard.

 

[rbbert]

Yes. I've seen this tube labeled Phillips, Amperex, and Mullard.

I believe Mullard also made this tube in the UK; the Philips and Amperex are probably from the same factory in Holland

 

[dminches]

Great tube - best 5AR4 ever made - used one in my Modwright PS 9.0 for several years. The only rectifiers I've tried in the PS 9.0 that surpassed it are the rare, expensive U52/5U4G/CV575 (labeled GEC/Osram/Marconi/MWT/Brimar), and Sophia Electric's new Aqua 274B - the only 274B which is a drop-in replacement for a 5U4G.

Why aren't other 274Bs, like the Takatsuki drop-in replacements?

 

[Cellcbern]

Why aren't other 274Bs, like the Takatsuki drop-in replacements?

A 274B cannot be used in place of a 5U4g or 5AR4 because of the limits on the value of the power supply capacitor that has to be used with a 274B. From Jeff Day's Positive Feedback review:

"......However, when the power supply capacitor is higher than 8 uF the long plate of the WE274B sparks, which forced Western Electric to limit the design requirement to 4 uF. This limitation prevented the 274B rectifier tubes from being used in a wide variety of applications, both in vintage times and today, as most modern equipment was designed with up to 47 uF capacitors as the first capacitor in the power supply so they could utilize 5U4G and 5AR4 rectifiers.....Sophia Electric has solved this limitation of the 274B in our Aqua 274B rectifier tube. Initially we tried to solve this limitation by using exotic materials, as in the design of our very popular Royal Princess 300B tubes, which utilizes platinum and rare earth materials. We were successful, but the finished product was way too expensive for the average consumer to be viable. Then we went back to the WE 274B structure design as a starting point, and in an unexpected way we figured out a way to solve the Western Electric limitation of 4uF. This solution allowed us to build the Sophia Electric Aqua 274B, which can use up to a 47 uF filter capacitor value, the same maximum value permitted for 5U4 and 5AR4 rectifiers.”

Far as I know Sophia Electric are the only ones to attempt this.

 

[dminches]

A 274B cannot be used in place of a 5U4g or 5AR4 because of the limits on the value of the power supply capacitor that has to be used with a 274B. From Jeff Day's Positive Feedback review:


Far as I know Sophia Electric are the only ones to attempt this.

I don't know if it is the design of the Lampizator Pacific or the 274Bs themselves but many of us have been using Acme and Takatsuki 274Bs without any problems. One can also use a 5U4G in the Pacific.

 

[robolton]

Thanks for chiming in, it was the box that was throwing me off. I had not seen one come in this box but someone just listed 2 for sale with same box. Has anyone compared 5AR4/GZ34 > 4-notch vs 7-notch vs smooth plate or comparison between F31 vs F32 vs F33 or Blackburn vs Holland?

 

[acousticsguru]

I believe Mullard also made this tube in the UK; the Philips and Amperex are probably from the same factory in Holland

As far as I know, the famous Metal Base was only made in The Netherlands from 1954-57 (should mention I've read 1951-58 more than once, but have come to doubt this is correct, as I've never seen one outside the aforementioned 4-year span), regardless of what the rebranding on them might say, and that includes the Mullard, which clearly state "Made in Holland" on them. Some of the later bakelite base GZ34s, the earliest of those being the so-called "Fat Base" (straight bottle), were made in the Blackburn factory.



Greetings from Switzerland, David.

 

[acousticsguru]

Thanks for chiming in, it was the box that was throwing me off. I had not seen one come in this box but someone just listed 2 for sale with same box. Has anyone compared 5AR4/GZ34 > 4-notch vs 7-notch vs smooth plate or comparison between F31 vs F32 vs F33 or Blackburn vs Holland?

Not all of them in direct comparison, unfortunately. This short video may be of interest:

Greetings from Switzerland, David.

 

[acousticsguru]

I don't know if it is the design of the Lampizator Pacific or the 274Bs themselves but many of us have been using Acme and Takatsuki 274Bs without any problems. One can also use a 5U4G in the Pacific.

According to Lukasz, one can use any rectifier without risk of damage in a Lampizator Pacific. Even though the capacitor in the Pacific is an 8µF (if memory serves), i.e. twice the size specified for the original WE 274b (of which the Takatsuki is a straight copy except for the thicker glass bottle), voltage and current are so low, we've even rolled historic tubes with adapters which I'd not try elsewhere for fear of arcing or blowing. 5U4G (up to 40µF) and 5AR4/GZ34 (up to 60µF) are safe to use anyhow.

Greetings from Switzerland, David.

 

[Cellcbern]

According to Lukasz, one can use any rectifier without risk of damage in a Lampizator Pacific. Even though the capacitor in the Pacific is an 8µF (if memory serves), i.e. twice the size specified for the original WE 274b (of which the Takatsuki is a straight copy except for the thicker glass bottle), voltage and current are so low, we've even rolled historic tubes with adapters which I'd not try elsewhere for fear of arcing or blowing. 5U4G (up to 40µF) and 5AR4/GZ34 (up to 60µF) are safe to use anyhow.

Greetings from Switzerland, David.

I have compared the metal base Phillps("Mullard") 5AR4 with the new blue Sophia 274B and the vintage CEC/Marconi/Osram U52 5U4G in the Modwright PS 9.0 power supply. Both are far superior to the metal base 5AR4. The vintage U52 is the best rectifier I've ever heard. The Sophia, which is the only 274B that is a direct drop-in replacement for a 5U4G, is very close but takes a couple hundred hours to settle down - it is initially very bright.

 

[acousticsguru]

I have compared the metal base Phillps("Mullard") 5AR4 with the new blue Sophia 274B and the vintage CEC/Marconi/Osram U52 5U4G in the Modwright PS 9.0 power supply. Both are far superior to the metal base 5AR4. The vintage U52 is the best rectifier I've ever heard. The Sophia, which is the only 274B that is a direct drop-in replacement for a 5U4G, is very close but takes a couple hundred hours to settle down - it is initially very bright.

Have you tried these in any other application than the Modwright? I don’t want people to jump to conclusions. The two NOS rectifiers you were mentioning our agreed-upon favorites and have been for decades. You’ll notice the Sophia isn’t a favorite with e.g. the Lampizator community at all (and not because anyone called it “bright“, Christoph et al. long since sold theirs), but some Decware and Modwright users appear to like it. Also, NOS would have really mean NOS or NIB in this context, as we’ve tried perfectly working (testing “good”) Miniwatt GZ34 Metal Base that sound solid-state-like and dull, the very contrary of one in great shape.

Apart from all this, you should consider yourself lucky to have gotten yourself a Sophia Electric that didn’t blow before the 200-hour burn-in was completed - you’ll notice on e.g. the Decware forum that people got multiple ones that were DOA.

In short, without greater context (e.g. recently tried a GZ34 Metal Base in both a Aries Cerat preamp and a Lampizator Pacific), generalizations aren’t helpful.

Greetings from Switzerland, David.

 

[acousticsguru]

I have compared the metal base Phillps("Mullard") 5AR4 with the new blue Sophia 274B and the vintage CEC/Marconi/Osram U52 5U4G in the Modwright PS 9.0 power supply. Both are far superior to the metal base 5AR4. The vintage U52 is the best rectifier I've ever heard. The Sophia, which is the only 274B that is a direct drop-in replacement for a 5U4G, is very close but takes a couple hundred hours to settle down - it is initially very bright.

To put it another way, in our Lampizator rectifier shootout, we had a GZ34 Metal Base that maybe didn’t come in dead last, but you get the gist, whereas we recently tried another that I’d put among my all-time (three or so) favorites along with, among other, the Takatsuki 274b.

Greetings from Switzerland, David.

 

[Cellcbern]

Have you tried these in any other application than the Modwright? I don’t want people to jump to conclusions. The two NOS rectifiers you were mentioning our agreed-upon favorites and have been for decades. You’ll notice the Sophia isn’t a favorite with e.g. the Lampizator community at all (and not because anyone called it “bright“, Christoph et al. long since sold theirs), but some Decware and Modwright users appear to like it. Also, NOS would have really mean NOS or NIB in this context, as we’ve tried perfectly working (testing “good”) Miniwatt GZ34 Metal Base that sound solid-state-like and dull, the very contrary of one in great shape.

Apart from all this, you should consider yourself lucky to have gotten yourself a Sophia Electric that didn’t blow before the 200-hour burn-in was completed - you’ll notice on e.g. the Decware forum that people got multiple ones that were DOA.

In short, without greater context (e.g. recently tried a GZ34 Metal Base in both a Aries Cerat preamp and a Lampizator Pacific), generalizations aren’t helpful.

Greetings from Switzerland, David.

I didn't make any generalizations. I said up front that I had tried the tubes in the Modwright power supply. I have however heard them in tube amps and preamps in other people's systems and was similarly impressed. My Sophia Aqua 274B has been going strong for two years now. I've only ever had a problem with one Sophia tube - an EL34, and it was replaced immediately at no charge.

 

[Cellcbern]

To put it another way, in our Lampizator rectifier shootout, we had a GZ34 Metal Base that maybe didn’t come in dead last, but you get the gist, whereas we recently tried another that I’d put among my all-time (three or so) favorites along with, among other, the Takatsuki 274b.

Greetings from Switzerland, David.

FYI(scroll down to see the rectifier comparison): https://jeffsplace.positive-feedbac...-san-alan-sans-gec-px25-monaural-sets-part-2/

Sophia Electric EL34-ST tubes

Sophia Electric EL34-ST tubes

positive-feedback.com

 

[acousticsguru]

I didn't make any generalizations. I said up front that I had tried the tubes in the Modwright power supply. I have however heard them in tube amps and preamps in other people's systems and was similarly impressed. My Sophia Aqua 274B has been going strong for two years now. I've only ever had a problem with one Sophia tube - an EL34, and it was replaced immediately at no charge.

Good for you! Even including the extended warranty, the Sophia costs half or a third of a GZ34 Metal Base.

Greetings from Switzerland, David.

 

[Cellcbern]

Good for you! Even including the extended warranty, the Sophia costs half or a third of a GZ34 Metal Base.

Greetings from Switzerland, David.

Anyone willing to pay the cost of a metal base GZ34 should look for a U52 instead. Prices are similar but the U52 superior to the metal base GZ34 in all significant parameters.