GZ34 sanity check
- Thermionic Idler
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#1 GZ34 sanity check
I believe I have this right but just want to "check my working".
For my 300B project, the circuit I'm basing it on has the power supply wired thus:
The power supply on the right uses the 6CJ3 which does NOT have the heater connection tied to the cathode. Therefore the centre tap of the heater supply has been tied to ground. The power supply on the left has an unspecified rectifier valve and also has the centre tap of its heater supply tied to ground (highlighted).
My plan is to use the GZ34 in both power supplies which, although indirectly heated, has the cathode tied to the heater. I believe that because of this, the 5v supply should not be grounded, with the idea being that it follows the changes in voltage at the cathode. Am I right?
For my 300B project, the circuit I'm basing it on has the power supply wired thus:
The power supply on the right uses the 6CJ3 which does NOT have the heater connection tied to the cathode. Therefore the centre tap of the heater supply has been tied to ground. The power supply on the left has an unspecified rectifier valve and also has the centre tap of its heater supply tied to ground (highlighted).
My plan is to use the GZ34 in both power supplies which, although indirectly heated, has the cathode tied to the heater. I believe that because of this, the 5v supply should not be grounded, with the idea being that it follows the changes in voltage at the cathode. Am I right?
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
- Cressy Snr
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#2 Re: GZ34 sanity check
Don’t whatever you do, ground the centre tap of the rectifier winding. You’ll burn out the mains transformer.
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- pre65
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#3 Re: GZ34 sanity check
You could take the HT from the 5V centre tap.Cressy Snr wrote: ↑Sun Aug 16, 2020 2:53 pm Don’t whatever you do, ground the centre tap of the rectifier winding. You’ll burn out the mains transformer.
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- Cressy Snr
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#4 Re: GZ34 sanity check
Exactlypre65 wrote: ↑Sun Aug 16, 2020 3:01 pmYou could take the HT from the 5V centre tap.Cressy Snr wrote: ↑Sun Aug 16, 2020 2:53 pm Don’t whatever you do, ground the centre tap of the rectifier winding. You’ll burn out the mains transformer.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
- Thermionic Idler
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#5 Re: GZ34 sanity check
So I'm right in other words
I was looking at the Olson drawing and suddenly thought - hang on, with a GZ34 that's a short circuit waiting to happen.
To be faiir, it had probably been quickly edited to use a recifier instead of the diodes and doesn't specify any link between the cathode and heater.
I was looking at the Olson drawing and suddenly thought - hang on, with a GZ34 that's a short circuit waiting to happen.
To be faiir, it had probably been quickly edited to use a recifier instead of the diodes and doesn't specify any link between the cathode and heater.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
- izzy wizzy
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#6 Re: GZ34 sanity check
The gz34 and 6cj3 are indirectly heated so take the HT off the cathode.
The 6cj3 is a damper and has very high heater cathode rating. Not so gz34.
Ref the gz34 heater to the cathode.
The symmetric reichert has some left overs from the karna and do can be a bit confusing.
The 6cj3 is a damper and has very high heater cathode rating. Not so gz34.
Ref the gz34 heater to the cathode.
The symmetric reichert has some left overs from the karna and do can be a bit confusing.
#7 Re: GZ34 sanity check
Yep, the damper diodes can stand that voltage between the heater and cathode, the indirectly heated normal rectifiers can't, and the directly heated has no cathode. Also make sure when you get the transformer wound that the heater winding is spec'd to run at the voltage you are intending to use it at. You can use a simple toroid with the damper diode and ground the heater supply to protect the transformer. A normal rectifier would need a heater winding that's safe to run at 600v or so above the core.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- izzy wizzy
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#8 Re: GZ34 sanity check
Although the sym reichert is a thought experiment, I'm guessing Lynn will have drawn it to use a dual damper for the front end and so could ref the heater to ground (probably). Maybe 6by5. 6cj3 would have been completely ott for 6sn7 front end. In the Karna he ran all 4 6cj3 from the same winding and so ref'd the lot to 0v.
- Thermionic Idler
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#9 Re: GZ34 sanity check
I'm planning on using two off-the-shelf Hammond models, the 375X and 378X rather than custom wind (in an effort to stop costs completely spiralling out of control ). Both have 5v and 6.3v secondaries and I'm anticipating that the 5v winding was intended for use with rectifiers. The datasheet only mentions primary to secondary maximum potential difference, given as 2500V.Nick wrote: ↑Sun Aug 16, 2020 5:36 pm Yep, the damper diodes can stand that voltage between the heater and cathode, the indirectly heated normal rectifiers can't, and the directly heated has no cathode. Also make sure when you get the transformer wound that the heater winding is spec'd to run at the voltage you are intending to use it at. You can use a simple toroid with the damper diode and ground the heater supply to protect the transformer. A normal rectifier would need a heater winding that's safe to run at 600v or so above the core.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
#10 Re: GZ34 sanity check
That should be fine. Will be on a bobbin unlike a typical toroid.Thermionic Idler wrote: ↑Sun Aug 16, 2020 7:16 pmI'm planning on using two off-the-shelf Hammond models, the 375X and 378X rather than custom wind (in an effort to stop costs completely spiralling out of control ). Both have 5v and 6.3v secondaries and I'm anticipating that the 5v winding was intended for use with rectifiers. The datasheet only mentions primary to secondary maximum potential difference, given as 2500V.Nick wrote: ↑Sun Aug 16, 2020 5:36 pm Yep, the damper diodes can stand that voltage between the heater and cathode, the indirectly heated normal rectifiers can't, and the directly heated has no cathode. Also make sure when you get the transformer wound that the heater winding is spec'd to run at the voltage you are intending to use it at. You can use a simple toroid with the damper diode and ground the heater supply to protect the transformer. A normal rectifier would need a heater winding that's safe to run at 600v or so above the core.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.