• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Aikido All In One Noval PCB - Heater Connections

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Member
Joined 2005
Paid Member
Decided to start a new thread and not thread jack an existing thread...

OK, so I built the Aikido all in one Noval - with 6N1P on front end and 6H30 on back years ago - sounds nice!...

But something has always annoyed me - I hooked up the Hammond tranny (way overkill, but all I had when I built it) and have the 6.3v - 6.3v secondaries for heaters to the Aikido and after its regulation, the heaters are only seeing 5vdc. The losses in regulation circuit drop the heater voltage (duh) - and when I re-read the instructions it recommended 7v - 7v+ secondaries for the heaters, so the regulation can drop to somewhere around 6vdc.

I know Broskie proclaims 5vdc is sonicly ok and will lead to longer tube life...but know many disagree...and I wonder if I should just plop in another transformer, or just pull the regulation transistor for the heater circuit...

I cant be the ONLY ONE that has seen this issue....right?

Soooo....Could / Should this Aikido sound better with a full 6.3v on heaters?

Thanks!!!
 
Read the valve data sheet. They don't state limits on the heater voltage for nothing. Low voltage heaters leads to excess cathode electron stripping and shorten the valve life.
Here is a screen shot of the 6n1p data sheet.
 

Attachments

  • Screenshot 2019-12-24 at 17.57.06.png
    Screenshot 2019-12-24 at 17.57.06.png
    65.1 KB · Views: 133
Member
Joined 2005
Paid Member
Edit to below response- but wait, isn't output of a voltage multiplier / doubler DC? Doesn't the heater input of the All in one PCB need AC?


Doublers? A Voltage Multiplier?

Guess I did not think of that, but when just about every transformer is 6.3vac (well, or 12.6v), why not add this voltage multiplier tip to the instructions, or maybe on the PCB?

I know, I'm a dope....
 
Last edited:
Member
Joined 2005
Paid Member
OK, so I am not going crazy, the All in One I have is version 1, and does not have the onboard doubling circuit (I was reading the manual for newer version All in One), so I don't feel quite so dumb...

Anyway, looking like there is no quick and easy way to get the regulated 6.3vdc on heaters except put a 12.6v transformer on it...

But I do have an unused 5v tap off this transformer - If connect them in series with 6.3v secondaries to get 11.3vac - the 5v secondaries is 3A, while the 6.3v is 5A. The total heater draw for the 6N1P / 6H30 is 600ma x 4 = 2.4A...

Good idea?

Its a Hammond 270FX
 
Last edited:
Member
Joined 2005
Paid Member
Well, all good - I was getting 1.5vac unloaded after series connecting the heater voltages, so reversed the 5v wires and now getting around 13vac series connected, unloaded.

Hopefully the different current ratings (5A@6.3v vs 3A@5v) is OK if only running at a total of 2.4A.

Now running good where its is supposed to be...
 
Hi. I may have had a vaguely similar issue on my 6sn7/300b amp. The circuit require 5v DC for the 300b heater filament although I have read of many using ac with hum pots. I used a 6v filament transformer with dual secondaries (hammond 266LA12). Using a standard 4 legged bridge rectifier the rectified ac after the BR was about 6v. This fed an LT1085 voltage rectifier but the headroom was not enough to get a clean 5v. Adjusting the voltage down to 4.7v out improved the ripple. A 266L12 rated at 30 va has worked ok in another's build. I ended up going for a toroidal 6v 30va dual secondary which worked out cheaper here. I still have a minute amount of ripple noise after switching on but soon becomes inaudible.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.