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GU-46 push-pull & single-ended amplifiers
GU-46 push-pull & single-ended amplifiers
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Old 17th July 2018, 11:34 AM   #121
palmas is offline palmas  Portugal
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Join Date: Jun 2007
seams a waste to use the GU46 with such a low voltage and tiny PSU.
GU46 is better over 1500V and 250mA
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Old 19th July 2018, 11:01 PM   #122
multi is offline multi  Australia
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Why would it be better? Sounds better? To USE 1500 Volts and 250 Ma. the Japanese have found many Tubes sound better at lower voltage, like the 833. I run 572B's at 600 volts 70 Mills very Good sound over 100 Watts

Phil
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Old 12th November 2018, 03:22 PM   #123
thomasweissbach is offline thomasweissbach  Switzerland
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Default Up Date, ongoing work on PSU

All transformers and chokes have finally arrived.

Nearly 40kg of custom wound toroid transformers from toroid.pl

Nearly 40kg of output transformers and custom wound chokes from ogonowski.eu

Output Transformer SE 150W 4.5k/8&16Ohm, 13.7kg in EI 150/93 - 16 Ohm tab will be used as 8Ohm tab to get 150W, 2.2k/8Ohm


First level with transformers, safety diodes, rectifiers, "low" voltage chokes (650VDC), russian 4uF caps.
Seconds level with high voltage chokes (1200 VDC) and caps.
Rectifier Tubes: 4x 5C8S per channel

Schematics will be updated
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Last edited by thomasweissbach; 12th November 2018 at 03:26 PM.
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Old 12th November 2018, 03:29 PM   #124
jazbo8 is offline jazbo8
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GU-46 push-pull & single-ended amplifiers
Looking real good!
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Old 12th November 2018, 04:03 PM   #125
thomasweissbach is offline thomasweissbach  Switzerland
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Hi jazbo
Wiring is a bit messy on the lower level, but this is on the AC side only, DC is less messy.

The amp is a stereo amp, all parts in one rack, made of industrial aluminium profiles and plates. High voltage areas will be covered with 6mm plexy.

A Siemens Logo 8 will manage the start up and shut down procedure of the amplifier, switching heater transformers, bias transformers, high voltage transformers and the signal relais on and off.
Including a safety loop for closed housing.

Low ampere DC heaters will be regulated with tentlab supplies - why reinvent the weel.

For the GU-46 I am still looking for a good DC regulating solution, 13V unregulated DC in, 8.3V regulated DC Out at 15A.

Does anyone have a simple and effective schematic for these currents?

Last edited by thomasweissbach; 12th November 2018 at 04:09 PM.
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Old 12th November 2018, 10:32 PM   #126
kodabmx is offline kodabmx  Canada
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You could use one of these but I dunno if you want to go switching...
https://www.ebay.ca/itm/DC-DC-Conver...LmDA:rk:2:pf:0
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Old 13th November 2018, 06:13 AM   #127
jazbo8 is offline jazbo8
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GU-46 push-pull & single-ended amplifiers
Quote:
Originally Posted by thomasweissbach View Post
For the GU-46 I am still looking for a good DC regulating solution, 13V unregulated DC in, 8.3V regulated DC Out at 15A.
I'd try just plain AC heating to start, hum may not be an issue at all.
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Old 14th November 2018, 09:19 AM   #128
thomasweissbach is offline thomasweissbach  Switzerland
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@ kodabmx I would prefer to go the classic way with a voltage regulator


@ jazbo AC heated GU-46, even with a SE output stage? I am a bit afraid to so, I wouldn't want to reopen the box for just having chosen the easiest way in the worst case.

Does anyone else have experience with voltage regulators for low voltages (8.3V DC) in high current environments (15++ A)?

Last edited by thomasweissbach; 14th November 2018 at 09:28 AM.
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Old 2nd December 2018, 07:28 AM   #129
thomasweissbach is offline thomasweissbach  Switzerland
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I have just finished my high current regulator for the GU-46

It works pretty well, set up as follows

- bridge rectifier 60A/40V
- SL32-2R005
- Common mode choke 1.3mH/20A
- 300000uF Sprague Powerlytic 36DX
- Elvees's regulator (see link below, Post #5)
delivering 8.3V DC with not measurable AC

Unfortunately my GU-46 tube seems to have lost vacuum, it develops smoke inside when heated, something I have never seen in any other tube. Tube will be replaced.


Low voltage regulator for high current consumer
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Last edited by thomasweissbach; 2nd December 2018 at 07:34 AM.
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Old 2nd December 2018, 10:55 AM   #130
thomasweissbach is offline thomasweissbach  Switzerland
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Tested with a new tube, very stable at 8.3V DC, 10mV of AC measurable.
The set up needs 20s to power up completely.
Schematics will follow when the amp is finished.
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