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Frank Lucas[_2_] Frank Lucas[_2_] is offline
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Default GZ34

So I've decided to buy two brand new JJ's GZ34 for my two mono 2A3 amps.
JJ's are cheap and I thought that if they were to last a few months
before selling the amps they were good enough.
I replaced the old chinese Golden Dragons (5AR4) and everything worked
flawlessly. The sound was a bit thin but I thought it was just matter of
waiting a few days for the tubes to express themselves better.
Then when I was going to leave everything as it was and replace the amps
with the love of my life the Dynaco ST35 ...

A friend stopped by with a bag of old Mullards GZ34 to put in those amps
and the something really strange happened.

I always prefer double blind testing, I'm an atheist, I don't believe in
cable magic or snake oil or in Bolduc's mystical runes and I trust my
ears more than my eyes.

The difference between the sound with the JJ's and the one with the
Mullards is so clear that even being in another room you could feel the
change. Dynamics, bass response, sweetness ... I was stunned.

The difference when we tried to swap the humble Guiguang monoplate 2A3Bs
with the pricey AVVTs was almost inexistent apart from the latter being
too metallic and so the worst of the two. Great difference was achieved
instead when we tried a couple of Marconis NOS.

Further investigation with the use of a scope and a signal generator
showed that with the Mullards the sag was less and recovery was faster.

Would a couple of solid state rectifiers with a properly calculated
series resistances and maybe a standby switch act better than the mighty
Mullards?

The 35 is still on a shelf waiting ...

Are there any brand of GZ34 or 5AR4 that resemble the sound of the
Mullards or in other words that act electronically like Mullards?

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martin martin is offline
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On 2017-04-22, Frank Lucas wrote:
So I've decided to buy two brand new JJ's GZ34 for my two mono 2A3 amps.
JJ's are cheap and I thought that if they were to last a few months
before selling the amps they were good enough.
I replaced the old chinese Golden Dragons (5AR4) and everything worked
flawlessly. The sound was a bit thin but I thought it was just matter of
waiting a few days for the tubes to express themselves better.
Then when I was going to leave everything as it was and replace the amps
with the love of my life the Dynaco ST35 ...

A friend stopped by with a bag of old Mullards GZ34 to put in those amps
and the something really strange happened.

I always prefer double blind testing, I'm an atheist, I don't believe in
cable magic or snake oil or in Bolduc's mystical runes and I trust my
ears more than my eyes.

The difference between the sound with the JJ's and the one with the
Mullards is so clear that even being in another room you could feel the
change. Dynamics, bass response, sweetness ... I was stunned.

The difference when we tried to swap the humble Guiguang monoplate 2A3Bs
with the pricey AVVTs was almost inexistent apart from the latter being
too metallic and so the worst of the two. Great difference was achieved
instead when we tried a couple of Marconis NOS.

Further investigation with the use of a scope and a signal generator
showed that with the Mullards the sag was less and recovery was faster.

Would a couple of solid state rectifiers with a properly calculated
series resistances and maybe a standby switch act better than the mighty
Mullards?

The 35 is still on a shelf waiting ...

Are there any brand of GZ34 or 5AR4 that resemble the sound of the
Mullards or in other words that act electronically like Mullards?

I cant answer that question but I am interested because in the 60's
in fact from 65 to 71 I worked in the Mullard stores in Mitcham
where lorryloads of valves used to come in unmarked, apart from
a datecode round the base, which i dont remember any more, we always
knew they were the best. THe only equivalents in those days were
Russian valves, which were used in some marine equipment.
I has been interesting reading these threads, and i still have a
copy of Radio Valve Data from 1961.

--
Martin

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Peter Wieck Peter Wieck is offline
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Default GZ34

The answer is pretty basic as you found:

Modern off-shore 5AR4s are crap. They will not pass enough clean DC current for the amp(s) to operate properly.

There are after-market solid-state 5AR4s which are adequate, far better than the Chinese/Russian garbage. Search for "WEBER COPPER CAP", and you will find the one with the best reputation *and* a built-in delay.

And there are delay boards (15 seconds is suggested) that may be had as well. Neither of these devices likes short-cycling, so do understand that before investing in them.

The most common mod on the Weber is to remove the cover, ventilate it, and then put it back. They get HOT!

Peter Wieck
Melrose Park, PA


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Frank Lucas[_2_] Frank Lucas[_2_] is offline
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On 23/04/2017 23:46, Peter Wieck wrote:
The answer is pretty basic as you found:

Modern off-shore 5AR4s are crap. They will not pass enough clean DC current for the amp(s) to operate properly.

There are after-market solid-state 5AR4s which are adequate, far better than the Chinese/Russian garbage. Search for "WEBER COPPER CAP", and you will find the one with the best reputation *and* a built-in delay.

And there are delay boards (15 seconds is suggested) that may be had as well. Neither of these devices likes short-cycling, so do understand that before investing in them.

The most common mod on the Weber is to remove the cover, ventilate it, and then put it back. They get HOT!

Peter Wieck
Melrose Park, PA



I've read lot of positive reviews about Matsu****a nos 5ar4/gz34 made
using Mullard machines. Maybe I'll try them one of these days.
I'd like to build some solid state rectifiers using some resistor to
simulate the voltage drop typical of a tube rectifier to leave the amp
circuit untouched in the bias voltage section but I'd also like to build
them with some kind of soft start to avoid the standby switch.
I really want to know what's inside those Webers ...

Frank
Florence, Italy
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Peter Wieck Peter Wieck is offline
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On Tuesday, April 25, 2017 at 5:48:52 PM UTC-4, Frank Lucas wrote:
On 23/04/2017 23:46, Peter Wieck wrote:


I really want to know what's inside those Webers ...

Frank
Florence, Italy


http://www.tdpri.com/threads/solid-s...estion.182474/

Here it is. They do work, reasonably well.

Peter Wieck
Melrose Park, ,PA



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Big Bad Bob Big Bad Bob is offline
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On 04/26/17 05:15, Peter Wieck wrote:
On Tuesday, April 25, 2017 at 5:48:52 PM UTC-4, Frank Lucas wrote:
On 23/04/2017 23:46, Peter Wieck wrote:


I really want to know what's inside those Webers ...

Frank
Florence, Italy


http://www.tdpri.com/threads/solid-s...estion.182474/

Here it is. They do work, reasonably well.


I expect a simple series resistor does the trick, but an actual tube's
behavior might be nonlinear...
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Peter Wieck Peter Wieck is offline
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On Tuesday, July 25, 2017 at 3:55:33 AM UTC-4, Big Bad Bob wrote:

I expect a simple series resistor does the trick, but an actual tube's
behavior might be nonlinear...


Yes. The 5AR4/GZ34 and related clones are a (relatively) slow-onset rectifier that (theoretically) allows the output tubes to get hot before seeing B+. This, thereby, reduces the strain on the filter caps.

The Weber "copper top" et.al. solid-state replacements are not quite as slow, but neither are they as expensive as a decent 5AR4, and also should last longer.

Peter Wieck
Melrose Park, PA

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