doubts for the 10 tube heaters

good morning
gentlemen, I have to power 10  6N16b tube for a project that I will share as soon as I will end it.
First doubt :
the HT is 200VDC , and since There's a lot of cathode follower and some of those DC coupled, Have I to elevate the filament even if  max VgK in 6N16B are 150 V and I have biased each of those approx -3V ( 100V ) ?  actualy little less -2.88
Second doubt :
each tube eat 400mA -/+ 10%  at 6.3V, so for power those in parallel this mean to use 4 Amps and a tons of UF, more over the kick of the inrusch current will be tremendous
If I power the filament in series with a current regulation instead, may I gain somethig ? maby using two regulators  to power 5 tubes each..
third one :
If I'll go for series ipotesi, have I to elevate the filament anyway ?

here's what I mean




M.

Don't bother with inefficient linear heater supplies. Instead use a SMPSU. I currently wire my heaters for 12V and use a MeanWell 100W 12V SMPSU (something like their LRS-100-12). It has hiccup mode short circuit protection which handles tube heater inrush current with ease. It is not bigger than the big transformer you need for the linear version, it is weighs a lot less and runs a lot cooler. I have not had any noise problems with them.

Yes, with cathode followers you really do need to elevate your heaters. I would recommend elevating them to about 25% of the HT supply.

Cheers

Ian

Hi Jan thank you,
yes, i've thought about this, I own one of this SMPSU, I use to use it to test some circuit but I really never use one of those in a project because  there's few think that scary me. First:  they need a good filter LC  in output and input too, and it is not as trivial, and second :  because  elevation is needed special attention is required.
this project is intented for diyers not noobe anyway, but it is mutch simple to hook up a tranformer then a SMPSU

M.

.

mik said:

Hi Jan thank you,
yes, i've thought about this, I own one of this SMPSU, I use to use it to test some circuit but I really never use one of those in a project because  there's few think that scary me. First:  they need a good filter LC  in output and input too, and it is not as trivial, and second :  because  elevation is needed special attention is required.

Click to expand...

You do not need an LC filter on the output for heaters. The input filter is built in to the power supply. 12V output SMPS are fully isolated by a transformer, just like a linear supply, so there are no problems with elevating the supply.

Cheers

Ian

PRR said:

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Click to expand...

thank you PRR, unfortunaly that solution is inapplicable because cathode follower are 10.

M.

ruffrecords said:

You do not need an LC filter on the output for heaters. The input filter is built in to the power supply. 12V output SMPS are fully isolated by a transformer, just like a linear supply, so there are no problems with elevating the supply.

Cheers

Ian

Click to expand...

I see ! so it should be possible, TME stock them and they are inexpencive.. good to know

built this supply in not the most lurid time of my life, don't know if it was the hillbilly heroin,  the snappers, maybe it was the moon rocks, or the mellow yellow, could have been the goodfella, watson-387, grievous bodily harm. or the miss emma or the cat tranqulizer, but it was not the ether because i can't solder with that stuff,

never the less, it has worked for about 15 years now after we removed all regulators except the Fairchild 670 B+ reg which works like a champ ,

no surge protection on that bridge circled in blue which feeds 276,000 uf, and it has not fired yet.

transformers are not that big, but the caps sure are! so i like the switcher idea, speeds have risen to the point where noise is way out of the audio band and easy to filter.

maybe Ian could list some switchers in this thread>

https://groupdiy.com/index.php?topic=57166.0

https://groupdiy.com/index.php?topic=57166.0

CJ said:

maybe Ian could list some switchers in this thread>

https://groupdiy.com/index.php?topic=57166.0

Click to expand...

Wilco

Cheers

Ian

Ian, did you test such a filament supply on sensitive circuit like tube preamp ?
On my rebuild of the 610A I have used a laptop PSU (19V) as the main supply and then several onboard DC/DC (which I designed) for the HT and filament supply. Testing the board shown an unexpected noise due to the filament supply, and I had to put 1mF caps near at the output of the DC/DC and near each tube to kill it.

Chris_V said:

Ian, did you test such a filament supply on sensitive circuit like tube preamp ?
On my rebuild of the 610A I have used a laptop PSU (19V) as the main supply and then several onboard DC/DC (which I designed) for the HT and filament supply. Testing the board shown an unexpected noise due to the filament supply, and I had to put 1mF caps near at the output of the DC/DC and near each tube to kill it.

Click to expand...

Yes I have tested it on a four pack of my tube mic preamps loaded into a 3U lunchbox with the PSU. I tested it with a MeanWell enclosed SMPS and the EIN was better than I have ever measured it with linear dc heater supplies. Laptop PSUs are notoriously noisy. I would not go anywhere near one for a heater supply. If you use a reputable manufacturer's SMPS you will be fine. I use MeanWell all the time now.

Cheers

Ian

We just tracked down an RF interferance problem blowing up Sennheiser wireless recievers to a laptop PSU, spraying junk when commands are typed. 

ruffrecords said:

Laptop PSUs are notoriously noisy. I would not go anywhere near one for a heater supply.

Click to expand...

This was definitively not an issue with the laptop PSU since the noise was identical with a linear lab PSU. This maybe related to the high switching frequency of the DC/DC (400kHz) coupling better and some subharmonic oscillations in the audio band.
Meanwell is using slighly better components than "very cheap chinese" manufacturers but the design and topologies are the same. Cheap AC/DC SMPS (and Meanwell is cheap) all suffer from noise issues, but there are solutions to deal with !

thank you gentelman,  I get some usefull input.

M.

OK, I'll do it.  Why does it have to be DC filament?

Chris_V said:

This was definitively not an issue with the laptop PSU since the noise was identical with a linear lab PSU. This maybe related to the high switching frequency of the DC/DC (400kHz) coupling better and some subharmonic oscillations in the audio band.
Meanwell is using slighly better components than "very cheap chinese" manufacturers but the design and topologies are the same. Cheap AC/DC SMPS (and Meanwell is cheap) all suffer from noise issues, but there are solutions to deal with !

Click to expand...

I am puzzled. You say the noise was the same with a linear lab supply, in which case the problem is neither the laptop or linear supply but something else. Please clarify.

Cheers

Ian

emrr said:

... Why does it have to be DC filament?

Click to expand...

because it's a PCB project, put AC filaments on trax seem to me bad idea

M.

Ian, the power tree for this 4 channel pre was as attached. DC/DC are my own design and embedded on the PCB.
My point was more on possible issue with SMPS on heaters, than on the meanwell itself. Laptop PSU are not good for noise, and not really realiable, you are true. In new design, I plan to use meanwell (or other) enclose SMPS, still keeping them outside of the rack.

Chris_V said:

Ian, the power tree for this 4 channel pre was as attached. DC/DC are my own design and embedded on the PCB.
My point was more on possible issue with SMPS on heaters, than on the meanwell itself. Laptop PSU are not good for noise, and not really realiable, you are true. In new design, I plan to use meanwell (or other) enclose SMPS, still keeping them outside of the rack.

Click to expand...

OK, that makes sense. I have successfully used a MeanWell inside a rack for heaters and it was no problem.

Cheers

Ian