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December 15, 2019, 12:20:56 AM

Author Topic: New BeePre Voltage Check  (Read 442 times)

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Offline grufti

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New BeePre Voltage Check
« on: August 15, 2019, 04:05:36 PM »
I completed my BeePre build about four weeks ago. I have since installed the BeeQuiet attenuator.

It's been completely smooth sailing throughout. The BeePre came to life without a glitch when I first powered it on. The BeeQuiet went in about ten days later, same thing. I'm loving the music. The BeePre is simply amazing.

I have the following tubes installed right now: electro-harmonix 300B Gold - new from TubeDepot - rated 68mA - 58mA/V and 67mA - 58ma/V respectively and 6P14P-EV new in box from Jac van de Walle in the shunt regulator. All tubes have about 100 hours on them right now and the amp had been on for roughly one hour when I measured voltages.

The line voltage was 124.3 VAC when I measured the voltages in the amp. I used a Fluke 175 DVM. I wont bore you with all the zeros. They were all zero. The voltages at 11 and 17 have me slightly concerned. What do you think?

300B Voltages

A
 1 - 4.913V
 2 - 108.3V
 4 - 9.85V
 6 - 144.5V  [-1.0%]
10 - 193.0V

B
11 - 143.6V  [-1.6%]
15 - 193.7V
16 - 4.961V
17 - 89.2V  [just outside of 90-110V range]
19 - 9.79V

most of the voltages at 22 - 43 are high

22 - 221.5V
25 - 220.5V
29 - 7.24V
30 - 7.24V
31 - 14.55V

34 - 14.57V
35 - 7.26V
36 - 7.25V
40 - 220.5V
43 - 220.5V

A2 - 108.3V
B2 -  89.2V

C3 - 4.877V  [high]
C7 - 144.9V
C9 - 144.2V

D3 - 4.585V  [slightly high]
D7 - 143.6V
D9 - 143.3V

Offline grufti

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Re: New BeePre Voltage Check
« Reply #1 on: August 15, 2019, 04:12:33 PM »
I forgot to mention that I would also like to see C7/C9 - D7/D9 come closer to the 147V target. I have used other tubes in the shunt regulator and those voltages have always come in below 147V.

I got the exact same voltages with a pair of Sylvania EL84 tubes when I re-measured right now just to make sure. C9 - 144.2V and D9 143.3V.
« Last Edit: August 15, 2019, 04:25:39 PM by grufti »

Offline Doc B.

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Re: New BeePre Voltage Check
« Reply #2 on: August 15, 2019, 04:53:37 PM »
Pour yourself a drink and enjoy some music. Those numbers are fine.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Paul Birkeland

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Re: New BeePre Voltage Check
« Reply #3 on: August 15, 2019, 05:17:33 PM »
The 90V is just indicative of lots of emission. 

The C7/9 and C7/9 come down to resistor tolerance.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline grufti

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Re: New BeePre Voltage Check
« Reply #4 on: August 20, 2019, 10:04:26 AM »
I adjusted some resistors and switched to another pair of 300B tubes in order to eliminate the one that was at the upper end of the 90-110V range at 108.3V. The measurements are better aligned now.

 4 - 9.86V
 1 - 4.843V
 2 - 86.7V
 6 - 146.9V
10 - 187.2

19 - 9.81V
16 - 4.883V
17 - 85.9V
11 - 147.0
15 - 187.6V

Doc, thank you, I did that too. I had actually been enjoying the music for a month already. This is just cleanup before the BeePre goes into the system.