FIY - a little work around for russian tube heater supply

[gtudoran]

Hey guys,

Don't know if it will help someone but, i'll post it ... may be it will
I was thinking how can i use a 6.3v heater with a 12v or 9v DC power supply - the answer was simple - use a LM317 regulator, but was not so simple in practice, as the heat it's going to be a PITA. The answer was, use a radiator for the LM317 ... but again the phisical space inside was too small (even with a 1590BB), so i was thinkig why not to use a the whole box as a radiator but the mechanical implication of mounting a LM317 and isolate the metal tab from the box will be a PITA too. Then today i've got it - the heaters don't care if you use negative voltage supply ore positive voltage supply - so why not use a LM337 for voltage regulation (the metal tab it's Vin wich is the negative wire of the power supply sooo... you can mount it directly on the aluminium box).

Hope this will help someone in the future.

Best regards,
Gabriel Tudoran
Analog Sound

[Morocotopo]

The only thing that comes to mind is, don´t exceed the max heater/grid voltage difference. Or was it heater/cathode? Hmmm.
Also, will your power supply be able to feed that much mA´s to the thing? Of course, I don´t know what tube you are talking about.

[gtudoran]

It's about heater/cathode voltage and that problem usualy comes in place for cathode followers. Regarding DC power supply i'm using 12v@ 1.5-2A power supply (the 6n16b and 6n17b will eat 350-400mA for heaters and the rest will be for SMPS DC supply wich supply the anode high voltage).


Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

Hey guys,

Don't know if it will help someone but, i'll post it ... may be it will
I was thinking how can i use a 6.3v heater with a 12v or 9v DC power supply - the answer was simple - use a LM317 regulator, but was not so simple in practice, as the heat it's going to be a PITA. The answer was, use a radiator for the LM317 ... but again the phisical space inside was too small (even with a 1590BB), so i was thinkig why not to use a the whole box as a radiator but the mechanical implication of mounting a LM317 and isolate the metal tab from the box will be a PITA too. Then today i've got it - the heaters don't care if you use negative voltage supply ore positive voltage supply - so why not use a LM337 for voltage regulation (the metal tab it's Vin wich is the negative wire of the power supply sooo... you can mount it directly on the aluminium box).

Hope this will help someone in the future.

Best regards,
Gabriel Tudoran
Analog Sound

or a resistor.... you have to dissipate the same power either way.

[frequencycentral]

Gabriel, that's such a good idea - really thinking outside the box. But I'd go with a 7906 instead of a LM337, it'll work in the same way as you suggest but will require less parts. Ok, it's gonna be 6v instead of 6.3v, but that still within spec. Thanks for sharing.

[gtudoran]

Hey guys,

Don't know if it will help someone but, i'll post it ... may be it will
I was thinking how can i use a 6.3v heater with a 12v or 9v DC power supply - the answer was simple - use a LM317 regulator, but was not so simple in practice, as the heat it's going to be a PITA. The answer was, use a radiator for the LM317 ... but again the phisical space inside was too small (even with a 1590BB), so i was thinkig why not to use a the whole box as a radiator but the mechanical implication of mounting a LM317 and isolate the metal tab from the box will be a PITA too. Then today i've got it - the heaters don't care if you use negative voltage supply ore positive voltage supply - so why not use a LM337 for voltage regulation (the metal tab it's Vin wich is the negative wire of the power supply sooo... you can mount it directly on the aluminium box).

Hope this will help someone in the future.

Best regards,
Gabriel Tudoran
Analog Sound

or a resistor.... you have to dissipate the same power either way.

That is also a possibility but keep in mind that heater current varyes (according to DS) from 0,33-0,41 according to this the value of the drop rezistor will also be different, the power that you will dissipate will be 2.28w this will req. at least 3w rezistor ...make it  5w to be sure, that would be a big rezistor that will not have the possibility to dissipate the heat on an radiator - that heat + tube heat + SMPS heat will make a nice oven.
@frequencycentral: tryed with 7806 lon time ago ... but if i remember well had some problems - i will try agian tomorow when i will buy some 7906.

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

I used a LM317 and it also gets hot.. Very hot.. Burned out two of them using the case as a heat sink, and three trimmer pots, changed to a resister, has not burned out yet.. matter of fact, the 5 watt ceramic does not even get hot to the touch after an hour of use, the LM317 very hot.

I like the ideal of using negative voltage regulation to ensure you can connect it to the case, I don't like the voltage regulator in the case at all, especially with a SMPS being added. 

Its up to you and this is good information for people to use, I did not mean to sound like I was attacking, just adding in commentary.. 

The rest of this response is  informational for others since I believe you know this already. 

while current does very, it dose not move out side the specification the heater voltage.. as voltage rating is between +/- .63 or 10% volts or 5.67 to 6.93
9 ohms  @ .3 (my datasheet says .300 ma parallel +/- 6% for 12ax7 which )  amps gives you the 2.7 volts drop for 9 volts to .6 and is .81 watts --- if this goes to .41 you now drop 3.69 which puts you at 5.31 volts (which will work) but change to 8 ohms puts you at 6.6 and 5.72 respectively
from 12 volts you need to drop 5.7  so 5.7 / .3 = 19 ohms which is 1.71 watts

[gtudoran]

No offence taken iccaros. This sollution i was thinkg to use with russian submini tubes not with 12AX series. Regarding the LM317 i hope you insulated from the case bc the metal tab it's @ Vout (i do use thermal compound also). I've used a 337 yesterday and everything was good.

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

No offence taken iccaros. This sollution i was thinkg to use with russian submini tubes not with 12AX series. Regarding the LM317 i hope you insulated from the case bc the metal tab it's @ Vout (i do use thermal compound also). I've used a 337 yesterday and everything was good.

Best regards,
Gabriel Tudoran
Analog Sound

ya, I cheat, I have some thermal tape that is non conductive, check with meter to ensure that tab and case are not connected.

I am building a ax84 high Octane with (2) 6112 and a SE 5902 output.
I would be interested in seeing you design for the mini tubes, may give me better ideals. 

[gtudoran]

No offence taken iccaros. This sollution i was thinkg to use with russian submini tubes not with 12AX series. Regarding the LM317 i hope you insulated from the case bc the metal tab it's @ Vout (i do use thermal compound also). I've used a 337 yesterday and everything was good.

Best regards,
Gabriel Tudoran
Analog Sound

ya, I cheat, I have some thermal tape that is non conductive, check with meter to ensure that tab and case are not connected.

I am building a ax84 high Octane with (2) 6112 and a SE 5902 output.
I would be interested in seeing you design for the mini tubes, may give me better ideals. 

Does the 6112 are biasing just like ecc83? or you need different voltages? did you compute them according to graph?

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

No offence taken iccaros. This sollution i was thinkg to use with russian submini tubes not with 12AX series. Regarding the LM317 i hope you insulated from the case bc the metal tab it's @ Vout (i do use thermal compound also). I've used a 337 yesterday and everything was good.

Best regards,
Gabriel Tudoran
Analog Sound

ya, I cheat, I have some thermal tape that is non conductive, check with meter to ensure that tab and case are not connected.

I am building a ax84 high Octane with (2) 6112 and a SE 5902 output.
I would be interested in seeing you design for the mini tubes, may give me better ideals. 

Does the 6112 are biasing just like ecc83? or you need different voltages? did you compute them according to graph?

Best regards,
Gabriel Tudoran
Analog Sound

they do not, but for the start I wanted to make sure they even work so I used the HO values. I am now going back and calculating the line that the 12ax7 used and seeing what the equivalent line would be for the 6112. Right now I get audio that sounds good, when its not blocked by what I believe is blocking distortion. I am trouble shooting  a Pot issue, gain 1 only goes for overdrive to clean, not off as I expected. I will have audio today sometime to get some help and ensure its not my SMPS.

[gtudoran]

No offence taken iccaros. This sollution i was thinkg to use with russian submini tubes not with 12AX series. Regarding the LM317 i hope you insulated from the case bc the metal tab it's @ Vout (i do use thermal compound also). I've used a 337 yesterday and everything was good.

Best regards,
Gabriel Tudoran
Analog Sound

ya, I cheat, I have some thermal tape that is non conductive, check with meter to ensure that tab and case are not connected.

I am building a ax84 high Octane with (2) 6112 and a SE 5902 output.
I would be interested in seeing you design for the mini tubes, may give me better ideals.  

Does the 6112 are biasing just like ecc83? or you need different voltages? did you compute them according to graph?

Best regards,
Gabriel Tudoran
Analog Sound

they do not, but for the start I wanted to make sure they even work so I used the HO values. I am now going back and calculating the line that the 12ax7 used and seeing what the equivalent line would be for the 6112. Right now I get audio that sounds good, when its not blocked by what I believe is blocking distortion. I am trouble shooting  a Pot issue, gain 1 only goes for overdrive to clean, not off as I expected. I will have audio today sometime to get some help and ensure its not my SMPS.

sh*tty sh*tty sh*t .... the same crap i'm into it right now ... over the original sound, there is a high zzzz that is only on the note decay... i've tryed also with a liniar power supply and the same, tryed with: anode caps, anode to grid caps, grid to ground caps, you name them tryed them all, if you have any ideea i would be glad to give it a try.
I will also post the schematic here, just in case you will see smth wrong.

Schematic MDD:


Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

Measure ac voltage on your first input grid...
I know mine was the SMPS, as I was seeing 150mv with no input on grid 1, and this was also on ground.  My SMPS just fried, moved a tube and bam... smoke.. I have a linear supply on order, a Hammond 269ax 125 -0 -125 with 6.3 @ 2.5 amps.

I don't know the pin out of your tubes, but the 6112 is
(1) Plate 1
(2) Grid 1
(3) Heater
(4) Cathode 1
(5) Cathode 2
(6) Heater
(7) grid 2
( plate 2

[gtudoran]

The pinout of 6n17B and 6n16b are the same as in schematic (you have pin numbers there)... hmmm don't know what to say about SMPS, the only AC component that should be on the B+ rail is the voltage ripple, if you had 150mV on the first grid from your first stage... that could be from the fact that the grid is not discharged... but that is also odd bc you are saing that the input was grounded.... hmmm...
I will check also this too see if it's the same.

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

I believe mine was oscillation from the SMPS.. They do that..
Also I believe a one spot is also a switching power supply which both together can cause noise..

here is a amp built with those russian tubes.. In case you want to compare.

http://www.users.rolskiego.net/zorba/nabla/

[~arph]

How about not wiring the heaters at all and illuminate them with a low power CO2 laser 

[gtudoran]

How about not wiring the heaters at all and illuminate them with a low power CO2 laser  

That is also an ideea ) ... like EHX if i remember well (the difference is that the used ordinary LEDs).

LE:  iccaros how did you get to that conclusion regarding SMPS oscillation? did smth put you on that way or was just a guess (i'm asking bc i'm in a state of mind that i would like to kill somme one )

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

How about not wiring the heaters at all and illuminate them with a low power CO2 laser  

That is also an ideea ) ... like EHX if i remember well (the difference is that the used ordinary LEDs).

LE:  iccaros how did you get to that conclusion regarding SMPS oscillation? did smth put you on that way or was just a guess (i'm asking bc i'm in a state of mind that i would like to kill somme one )





Best regards,
Gabriel Tudoran
Analog Sound

reading threads by Rick, P.R.R. and R.G. and others. I decided to connect this to a O-scope and see what I get. I could see that I was getting 150 mv @ 1.5 hz and this would range, so It would go up to 8 hz.. This is not normal ripple of 120hz or other AC ranges cycles...  looked more like http://en.wikipedia.org/wiki/Heterodyning where two frequencies coming together create a new one.

This is with no input connect, just a loop back to ground with a 1meg resistor.  Then as I moved through the grids I see it amplifying this signal.

[gtudoran]

Hmmm strange ... i will make this experiment right now. I've tryed to use a liniar power supply (about 1 hour ago) and that effect was diminished but was still there, i will put 1M to ground @ input and see what do i get on the scope.

Best regards,
Gabriel Tudoran
Analog Sound

[iccaros]

Hmmm strange ... i will make this experiment right now. I've tryed to use a liniar power supply (about 1 hour ago) and that effect was diminished but was still there, i will put 1M to ground @ input and see what do i get on the scope.

Best regards,
Gabriel Tudoran
Analog Sound

when you had the linear supply did you try elevating your heaters? or were you still running DC?? If DC did you try raising the ground seen by the heaters, this can kill hum that is transmitted over the heaters, and these submini tubes, the heaters are so close to the plates.....

Just an ideal..