DIY noob

bentlyg41 · 16th April 2012, 06:34 AM

hi there,

So for my first tube based DIY project, I am attempting to build a Tetra Sans PS Preamp. Working with electronics is not entirely foriegn to me. However, I'd like some guidance from guys and gals who have worked with this a little bit longer than I have. I'm pairing up the Tetra Sans PS Preamp (with 12AT7 tubes for the first and second stage), and the PS-1 power supply and heater. Any ideas or suggestions for a decent transformer. I'm able to wrap myself around picking out a decent transformer, but I'm a little weary of making the wrong choice. Any suggestions would be appreciated

boywonder · 03:04 PM

Well, from Broskie's site:

The Tetra Sans PS phono stage PCB requires an external power supply for its heater and B+ voltages. The heater power supply should deliver 12.6Vdc (or 12Vdc), as the 6V and 12V tubes can be used with this voltage; 6V tubes, such as the 6DJ8 and 6N1P, can have their heaters placed in series. In contrast, 12V tubes, such as the 12AX7, cannot be used with a 6.3Vdc power supply.

The high voltage power supply voltage depends on the tubes used. In general, 200Vdc to 340Vdc is needed.

What B+ are you planning for the 12AT7's?

The 12A*7 type tubes can be wired for 6.3V or 12.6V; however, it sounds like the PCB requires a 12.6V supply.

Have you looked at Edcor's power transformer offerings? They have lots of choices.

EDCOR

Duncan amps TDSL will tell you the required heater current for the 12AT7; looks like .15A for 12.6V wiring. It also shows some typical operating points.

TDSL Tube data [12AT7]

It looks like the PS-1 board will output 12VDC when using a power transformer with 24Vct, 12.6V or 6.3V heater windings, so that makes things pretty easy.

Once you know your desired B+ voltage, the current draw of the 4 tubes and heater current (total .6A for 4 12AT7's), you can select a power transformer. Since the PS-1 is regulated, you will also burn some current/power there as well. Keep in mind the more voltage that you drop in the PS-1, the more heat it will need to dissispate.

bentlyg41 · 16th April 2012, 10:03 PM

To be honest, I wasn't sure about the correct B+ voltage. I have come across Edcor before, but haven't made a sound decision

bentlyg41 · 17th April 2012, 06:23 AM

So I think I found a good transformer. Allied Electronics 6K88VG. I'll have to change the tubes so that they can work with the 6.3 V, but here are some stats on that transformer: "PRI:110-120V, 50/60HZ, 500VCT @40DCMA, 6.3V @ 2.0A, LEADS (Allied Site)." Not sure what you guys think of this, but I think it will work.

16th April 2012, 06:34 AM	#1
bentlyg41 diyAudio Member Join Date: Apr 2012 Location: Copiague	DIY noob hi there, So for my first tube based DIY project, I am attempting to build a Tetra Sans PS Preamp. Working with electronics is not entirely foriegn to me. However, I'd like some guidance from guys and gals who have worked with this a little bit longer than I have. I'm pairing up the Tetra Sans PS Preamp (with 12AT7 tubes for the first and second stage), and the PS-1 power supply and heater. Any ideas or suggestions for a decent transformer. I'm able to wrap myself around picking out a decent transformer, but I'm a little weary of making the wrong choice. Any suggestions would be appreciated

16th April 2012, 02:47 PM	#2
boywonder diyAudio Member Join Date: Jan 2008 Location: So.Cal.	Well, from Broskie's site: The Tetra Sans PS phono stage PCB requires an external power supply for its heater and B+ voltages. The heater power supply should deliver 12.6Vdc (or 12Vdc), as the 6V and 12V tubes can be used with this voltage; 6V tubes, such as the 6DJ8 and 6N1P, can have their heaters placed in series. In contrast, 12V tubes, such as the 12AX7, cannot be used with a 6.3Vdc power supply. The high voltage power supply voltage depends on the tubes used. In general, 200Vdc to 340Vdc is needed. What B+ are you planning for the 12AT7's? The 12A7 type tubes can be wired for 6.3V or 12.6V; however, it sounds like the PCB requires a 12.6V supply. Have you looked at Edcor's power transformer offerings? They have lots of choices. EDCOR Duncan amps TDSL will tell you the required heater current for the 12AT7; looks like .15A for 12.6V wiring. It also shows some typical operating points. TDSL Tube data [12AT7] It looks like the PS-1 board will output 12VDC when using a power transformer with 24Vct, 12.6V or 6.3V heater windings, so that makes things pretty easy. Once you know your desired B+ voltage, the current draw of the 4 tubes and heater current (total .6A for 4 12AT7's), you can select a power transformer. Since the PS-1 is regulated, you will also burn some current/power there as well. Keep in mind the more voltage that you drop in the PS-1, the more heat it will need to dissispate. Last edited by boywonder; 16th April 2012 at 03:04 PM.*

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16th April 2012, 10:03 PM	#3
bentlyg41 diyAudio Member Join Date: Apr 2012 Location: Copiague	To be honest, I wasn't sure about the correct B+ voltage. I have come across Edcor before, but haven't made a sound decision

17th April 2012, 06:23 AM	#4
bentlyg41 diyAudio Member Join Date: Apr 2012 Location: Copiague	So I think I found a good transformer. Allied Electronics 6K88VG. I'll have to change the tubes so that they can work with the 6.3 V, but here are some stats on that transformer: "PRI:110-120V, 50/60HZ, 500VCT @40DCMA, 6.3V @ 2.0A, LEADS (Allied Site)." Not sure what you guys think of this, but I think it will work.