[SoundBound]

I thought I would check the DC voltage levels of the Cornet II that I built, and even though it plays great and sounds great, I found that the measured voltages differ from those posted on the schematics and PCB.  The values I got are as follows:

Stated Voltage  (my measured voltages)
365 (342)
155 (114)
330 (309)
300 (277)
150 (105) second stage check
150 (92) first stage check
6.2 (5.72) heaters

If anybody has any feedback whether this is common or a point of concern I would appreciate hearing back.  If it's not a big issue, then I will probably leave well alone as it sounds fine.
Thanks.
rick

[tubesforever]

I think you are using a 6106.  But is it new or is it used?  If it is down to the good level then it might be underpowering the B+.  It would be a good idea to keep a set of the stock spec'd tubes around so you can swap out and compare. 

In my build, with a 6106 my voltage was up 15% not down that amount.   Make sure you test this after about 15-20 minutes time with nothing connected out back.  Unplug it all except for the power cord.

Good luck!

[hagtech]

Yeah, the tube bias seem off.  Everything is a bit low.  What is your input ac voltage?

jh

[SoundBound]

Hi Jim
The input AC up here in Canada is 120 (measured with a multimeter it reads 118-119V).  So I used the transformer primary windings as indicated for a 120VAC hookup.



Should I have wired as per a 110VAC or could it be the Bendix 6106?

[hagtech]

Hard to say.  Do you have a 5AR4 / GZ34 around for comparison?  I worry about the low plate voltages on the 12AX7s.

jh

[SoundBound]

Jim; I was not aware that you could substitute the 5AR4 for the 5Y3 called for in the Cornet II design / parts list??    If this is the case, I will pick up a 5AR4 to check it out, I don't have one kicking around.

If you can use either the 5AR4 or the 5Y3, what are the advantages / disadvantages of either selection?  Just my curiosity.  Thanks.
rs

[hagtech]

I did the original design using a Sovtek 5Y3, which turned out to be indirectly heated and had a nice slow warmup time.  Only after that did I realize the NOS weren't like that.  So the 5AR4 gives a more gentlw turn-on.  Perhaps fewer "thumps" getting through.

jh