Another 6AV5 Get.Set.Go Build...

2nd harmonics for the masses

Another 6AV5 Get.Set.Go Build...

Postby jwhitmor » Mon Mar 02, 2015 2:15 am

The 6B4G and 300B tubes I could locate from reliable sources were all pretty expensive, so I went with 6AV5 tubes. They sound fabulous, and my only complaint is, my NOS GE 6AV5's are "microphonic". A light tap really makes them squawk, but not a problem in normal use. I drilled my own panel, and added vent holes above the diodes and power resistors. The top and back panels are one piece of metal so I can lift it out of the wood base and set it on the bench as a single unit. Shannon's PCB ensures success. I wired it up, put in a fuse, and threw the switch. After the tubes warmed up, I checked the speaker terminals with an oscilloscope, to verify there was no oscillation, or DC offset voltage. Everything was fine, so I hooked up the speakers and started listening to music. I wasn't certain if there really was a "break-in" period for electronic parts, but the sound improved noticably over the first couple hours of use.
(wine)
Attachments
GSG_02.JPG
The panels were hand drilled in my shop. The top is 12' wide X 9" deep.
GSG_02.JPG (635.41 KiB) Viewed 1956 times
GSG_03.JPG
The back panel lifts out with the top as a single unit.
GSG_03.JPG (465.62 KiB) Viewed 1956 times
GSG_04.JPG
The base is curly hard maple with cherry trim. The LED indicator, is powered off the DC tube heater supply through a 390 ohm series resistor
GSG_04.JPG (391.46 KiB) Viewed 1956 times
Last edited by jwhitmor on Mon Mar 02, 2015 4:23 pm, edited 1 time in total.
If it is not making X-rays, your B+ is too low.
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Re: Another 6AV5 Get.Set.Go Build...

Postby Geek » Mon Mar 02, 2015 3:27 am

Nice! Love the contrasting wood and artistic vent holes :))
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Re: Another 6AV5 Get.Set.Go Build...

Postby jwhitmor » Mon Mar 02, 2015 4:29 pm

Thank you for the kind words Geek,
I was not I sure I needed any vent holes, but I can feel warm air coming out of them. Much quieter than a fan, so I am happy I put them in.
If it is not making X-rays, your B+ is too low.
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Re: Another 6AV5 Get.Set.Go Build...

Postby zman01 » Tue Mar 03, 2015 8:28 pm

Very nice build you got there - enjoy! :)

The 6AV5GA tubes sound great in the GSG. Btw, what is B+?
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Re: Another 6AV5 Get.Set.Go Build...

Postby jwhitmor » Tue Mar 10, 2015 2:22 pm

With the Edcor XPWR005-120 transformer, the Sylvania NOS 6AX5G tube rectifier, 1.0 H - 240 mA Triad choke, and my house line voltage of 121 Vac, I measure a B+ of 301 Vdc with a Fluke Model 83 VOM. (with no input signal, and all tubes in place at operating temperature)

I have a NOS HP "Bright Plate" 6SL7GT (probably GE made) and a new Sovtek "Grey Plate" 6SL7GT. The Sovtek sounds (lots) better.
If it is not making X-rays, your B+ is too low.
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