[mpv]

You are looking at the Philips Production Code for this tube. (Mullard was a subsidiary company)

https://frank.pocnet.net/other/Philips/PhilipsCodeListAB.pdf

R7 = GZ32
1 = revision number
B= Blackburn, a Mullard factory
8 = 1958
H = August

So now you know the tube type, where it was manufactured and the date of manufacture.

Thanks a lot "gibosi"

 

[plb0202]

Do you have the Woo plugged into any power conditioner? For example, I use a Furman Elite-15i into which is plugged the CD transport, the DAC, the Woo WA2 (or WA6 or WA6SE). The Furman also protects from surges etc.

There is no power conditioning in place at this stage. I have been considering this. I am in Australia where we run 240V mains and I have no issues with my other audio kit, solid state amps, pre's, dacs etc. Have a voltage meter on the way so I can monitor and check the mains supply to the Woo to see if there is an over supply that may be causing this. It fired up this morning without blowing the fuse and tripping the circuit breaker in that part of the house.

 

[Monsterzero]

There is no power conditioning in place at this stage. I have been considering this. I am in Australia where we run 240V mains and I have no issues with my other audio kit, solid state amps, pre's, dacs etc. Have a voltage meter on the way so I can monitor and check the mains supply to the Woo to see if there is an over supply that may be causing this. It fired up this morning without blowing the fuse and tripping the circuit breaker in that part of the house.

dumb question, but do you have the amp set to 240v instead of 110?

 

[jonathan c]

dumb question, but do you have the amp set to 240v instead of 110?

I think the switch is for 230 / 115…But still, is 240v on a consistent basis too much for a 230v setting?…

 

[jonathan c]

There is no power conditioning in place at this stage. I have been considering this. I am in Australia where we run 240V mains and I have no issues with my other audio kit, solid state amps, pre's, dacs etc. Have a voltage meter on the way so I can monitor and check the mains supply to the Woo to see if there is an over supply that may be causing this. It fired up this morning without blowing the fuse and tripping the circuit breaker in that part of the house.

Also, something like the Furman will tell you the voltage coming through continuously.

 

[plb0202]

Also, something like the Furman will tell you the voltage coming through continuously.

Thanks @jonathan c Yes the Amp is set to the correct voltage. Some days its OK and somedays it blows...without changing anything in its config...maddening really

 

[plb0202]

I have been monitoring my power supply voltage from the mains. It moves around between 246 and 252V (Australia) I contacted Woo and they have indicated this is too high for the amps stock power tubes and this may be the issue. Hopefully we are getting to the bottom of the behaviour. Wanted to post the progress somewhere in case others run into a similar problem. Power regenerator looks like the way forward.

 

[David222]

I've been rolling through Dubstep Girls's comparison list with my new Woo Audio WA6. As many have noted in this thread, the GZ34 is fantastic. Was able to acquire an f31 / 1950s from Brent Jessee. Certainly curious what the metal base adds beyond

 

[gibosi]

I've been rolling through Dubstep Girls's comparison list with my new Woo Audio WA6. As many have noted in this thread, the GZ34 is fantastic. Was able to acquire an f31 / 1950s from Brent Jessee. Certainly curious what the metal base adds beyond

There were three different black base GZ34 manufactured by Philips. After Philips ceased making the metal GZ34 in Eindhoven, Holland, in 1957, these black-base tubes were manufactured in Sittard, Holland (factory code X), Blackburn, Great Britain, Mullard (factory code B) and Brussels, Belgium, MBLE Mazda (factory code L). And of course all these sound different. So the question is, which one do you have?

 

[plb0202]

There were three different black base GZ34 manufactured by Philips. After Philips ceased making the metal GZ34 in Eindhoven, Holland, in 1957, these black-base tubes were manufactured in Sittard, Holland (factory code X), Blackburn, Great Britain, Mullard (factory code B) and Brussels, Belgium, MBLE Mazda (factory code L). And of course all these sound different. So the question is, which one do you have?

My guess based on some googling is Blackburn given the treble clef on the glass.

 

[gibosi]

Unfortunately, the silk-screened text and logos printed on the side of the glass were mostly about marketing. And tubes branded Amperex with the Bugle Boy logo were destined to be marketed in the US. But it could have been made in any of Philips many factories. So you really can't trust these markings.

What you need to look for is the Philip's production code. Unless it has been rubbed off, it can be found on any Philips tube marketed after around 1948. With respect to GZ34, the early tubes had the code printed on the bottom of the base around the pins. Later tubes had the code etched into the glass on the side of the tube near the base.

Once you locate the code, you can then use the following document to tell you what kind of the tube it is (useful if the tube name has been rubbed off), where the tube was manufactured, and the date.

https://frank.pocnet.net/other/Philips/PhilipsCodeListAB.pdf

For example, a GZ34 manufactured in Sittard, Holland in 1957 = f30 X7L

f3 = GZ34
0 = revision number
X = Sittard, the factory
7 = 1957
L = November

Have fun!

 

[leftside]

There were three different black base GZ34 manufactured by Philips. After Philips ceased making the metal GZ34 in Eindhoven, Holland, in 1957, these black-base tubes were manufactured in Sittard, Holland (factory code X), Blackburn, Great Britain, Mullard (factory code B) and Brussels, Belgium, MBLE Mazda (factory code L). And of course all these sound different. So the question is, which one do you have?

Interesting. Something very similar happened with Philips in 1957 with the metal base EL34 also made in Eindhoven. And then the brown base and black base XF1EL34 tubes were made also in Blackburn, Brussels and Sittard. Very different tube construction in the Blackburn factory compared to the Brussels and Sittard factories though.

 

[David222]

There were three different black base GZ34 manufactured by Philips. After Philips ceased making the metal GZ34 in Eindhoven, Holland, in 1957, these black-base tubes were manufactured in Sittard, Holland (factory code X), Blackburn, Great Britain, Mullard (factory code B) and Brussels, Belgium, MBLE Mazda (factory code L). And of course all these sound different. So the question is, which one do you have?

X8L

 

[plb0202]

X8L

The last time I throw caution to the wind and guess!

 

[leftside]

X8L

Sittard 1958.