Paraglow II voltage check

[RPMac]

Here are the voltages on my Paraglow II with Tucker shunt/reg boards and 6N1P.
All Magnequest iron
PGP 8.1 power tfx & RGC-6 chokes
EXO-03 plate choke & EXO-36 opt

2A3 cathode resister 3.3K

#1_(as posted earlier)_____________________________________

121.3VAC in
378VAC out

483VDC
471VDC after CLC

on 2A3
452VDC  plate
202VDC cathode
158VDC grid

on 6N1P
B1 158VDC plate
B3 2.45VDC cathode (332 R)
B6 224.5VDC plate
B8 5.8VDC

DCR B+ windings 140 & 149

#2___________________________________________

123VAC in
388VAC out

490VDC
478VDC after CLC

on 2A3
459VDC  plate
203VDC cathode
158VDC grid

on 6N1P
B1 158VDC plate
B3 2.46VDC cathode (332 R)
B6 225VDC plate
B8 5.7VDC

DCR B+ windings 145 & 154

Both amps measured using the same tubes.

But still having an issue...
Sometimes the c4s/SR boards won't come on...LEDs won't light.
I can cut the power switch off, then back on and they light.
Any idea and is this a problem?

Also got a 4PDT on-off-on switch like voltsecond recommended and wired so I can switch between the Paraglows and Parabees through Heresy speakers. Paraglows were the clear winners until my wife pointed out the Paraglows were slightly louder. Pulled out the RS meter and sure enough, the Paraglows were about 1dB louder. Compared them again with +1 click volume when going to the Parabees. Much closer, but I have to give the edge in detail to the Paraglows.
Direct coupling the difference?
Shunt reg?
Got me thinking direct coupled Parabees.

With my BeePre coming, got me thinking again, any chance to use a DHT driver for an all-DHT Bottlehead system?

 

[Paul Joppa]

You were not clear about whether the LED problem occurs with one or both amps, and if both, is it at the same time? Basically, if it's the boards, you'll have to talk to Tucker since we don't have any debugging experience to rely on. You might want to be sure it's not a power switch problem, or a solder joint problem first.

Direct coupling forces a lower voltage across the power tube, since the grid and cathode are elevated by the driver plate voltage. So basically, the Paraglow IS a direct coupled Parabee.

Yes, we continue to research new designs. No, I am not ready to talk about any of them yet.

 

[RPMac]

Paul,
originally, it only happened with the one amp (#2).
When I wired in the 4PDT switch to use between the Paraglow and Parabee outputs, the switch had the speakers connected to the Parabees which had the Paraglows with no load on the speaker terminals. Neither Paraglow was on until I cut the power off, then back on. When on, the seem to be working fine.

Possibly another important point I left out...I'm running the amps on balanced power, 60-0-60.

For a direct-coupled 300b, I could rewire the filament for 5v on the Paraglow and plug in a 300b.
Isn't the JJ 2A3-40 suppose to be a 300b with 2.5v filaments?

I bought your soft start boards with the intention of using them on the Paraglows. I think I need to learn as much as I can getting the Paraglows to work properly before moving on. And I think it will take a complete rebuild to get the room I would need.

Thanks for the help.

 

[Paul Joppa]

... Neither Paraglow was on until I cut the power off, then back on. ...

Sorry, I didn't follow that - it appears to indicate there was no LED glow when the amp was not powered, which does not seem like a problem ... I'm pretty sure you meant something different though!  :^)  So, how many switches are you using - there is the power switch on each amp, the speaker switch, and possibly a power strip the amps are plugged into (?).

Aside from that, sure you can replace a 2A3 with a 300B by just changing the filament voltage. It will perform pretty much the same (power, voltage, current, gain, etc.) except for probably 6dB more hum from the filaments. You will of course hear the intrinsic timbral differences, such as mechanical vibration of the internal parts and linearity, and probably some things we haven't identified yet.

I can't see how the unloaded secondary or the balanced power can be a problem.

I applaud your careful, exploratory approach!

 

[RPMac]

Paul,
I apologize for not being more clear.
In my system, I have a Squeezebox feeding the FP III; one set of FP III outputs goes to the Paraglow pair and the other goes to the Parabee pair. The speaker outputs of the two pairs of amps goes to each side of the 4PDT speaker switch with the center going to the speakers. This is so I can A-B the amps.

The problem is that sometimes when I power on the Paraglows(mostly amp #2), the c4s/shuntreg boards won't come on and I can hear the music at extremely low volume. The last time this happened, the speaker switch was set that there wasn't any load on the two Paraglows when they were powered on.
I have found that when the boards don't light up, I can turn the power switch off, then back on and the amp will work as it should.

I know the hardest problem to diagnose is the one that randomly happens.
Thanks for your help.

 

[Paul Birkeland]

I'd recommend power cycling the amp until you can get it to "stick" in that problematic mode where you get low output, then measure the DC voltages.

There may be a funky cap or odd solder joint that becomes more obvious under these conditions.

-PB

 

[RPMac]

PB,
I replaced all the power supply caps and cathode bypass caps with CDE unl serie caps.
The amps sound great, so I'm going to play them 'til something breaks. My only concern would be damaging the MQ iron.

 

[RPMac]

Been playing my Paraglows every day since last post with no issues.
PB may have been right...terminal 6, where the power supply choke, plate choke, second cap, its bypass cap and B+ for the driver are all connected, was particularly ugly.

Terminal 6 is at 478v. Originally there was a 15K resister between T6 and the c4s/shuntreg board(B6). With help from another Bottlehead with Paraglows, I added 5K for a total of 20K now between T6 and the board. I know I have higher than normal B+ voltage and was wondering what should be the correct resistance.

Thanks
Robert