Seduction And Reduction Tube Equivalents

[Grainger49]

The specs I just read say each tube draws 600mA +/-50mA.  So on the outside that is 1.3A.  Give your self some room to rectify and filter the heaters.  Get at least 1.5A 6.3V transformer (Hammond 166L6).  You can use a three pin regulator chip and trim up the voltage to exactly what you want.  For that you should get a 1.5-2.0A 8V transformer (Hammond 166L8).

 

[Dobs]

Wich way is best?

Can i install the transformer into the Seduction without compromising the sound with electrical noise.

 

[Dobs]

The specs I just read say each tube draws 600mA +/-50mA.  So on the outside that is 1.3A.  Give your self some room to rectify and filter the heaters.  Get at least 1.5A 6.3V transformer (Hammond 166L6).  You can use a three pin regulator chip and trim up the voltage to exactly what you want.  For that you should get a 1.5-2.0A 8V transformer (Hammond 166L8).

On the spec i saw the hammond give 2a at 6.3v I assume its 6.3vdc? When you say 3 pins regulator chip you mean variable resistor?

 

[Grainger49]

Transformers produce AC so if you want to go with DC you have to use either a full wave bridge or four diodes arranged in a bridge, some capacitors and a resistor to smooth the rectified AC.

The three pin regulator is a good way to go for smooth and noise free DC.  (you still need everything mentioned above)

This part is an adjustable voltage regulator but with 5 pins (I couldn't find a three pin regulator):

http://www.mouser.com/ProductDetail/Sharp-Microelectronics/PQ070XH02ZPH/?qs=sGAEpiMZZMsGz1a6aV8DcJFN%252bbTDeMTjFe%2f59o4dkoI%3d

Edit: this transformer would have to be out of the Seduction chassis or it will hum.

It has 10V maximum input, 2A maximum current and is adjustable from 1.5 to 7 volts.

 

[Paul Joppa]

There are two problems with the Hammond transformers suggested, both of which mean that they will generate excessive magnetic hum fields and cannot be placed near the Seduction. (Without testing, I would guess that a minimum 12 inch distance would be adequate - but not in the same box!)

The first problem is a lack of magnetic headroom; the second is having the windings separated into two different bays of the bobbin. Note that the PT-1 runs 70-80 percent as much magnetic induction as the Hammonds, and still needs both a copper shield and a molyperm shield tape. This greatly increases the cost of this transformer and - you know Bottlehead - we would not do that unless we had to! My second attempt at a good phono preamp power transformer is the PT-5 in the Eros; it does not need the shield tapes but is much larger, so no cost savings there.

Our experience developing the Seduction - one of our earlier products - is what convinced us that we should use custom power transformers in all our products, designed for low-noise audio applications.

 

[Dobs]

I thought the Hammond was to be used as a stand alone supply for the heater only instead of a cheapo wall wart type, right?

 

[Grainger49]

An outboard power supply is indicated for this application.  It is not that hard to do.

 

[Doc B]

I hope i didnt damaged too much my transformer because im using 6N1P for about 2 years now with around 800h of play.

Actually I would say that you have proven that the PT-1 can be run way over spec and handle it pretty well. I'm not condoning this, as it could be that the transformer might fail for some one else running in this same condition of overload. But if it's already been running for two years for you without incident I wouldn't really expect a catastrophic failure...just don't ask us for warranty coverage if it goes. Strikes me that a simpler solution than changing the power supply is to go back to the tubes it was designed to work with.

 

[Dobs]

Transformers produce AC so if you want to go with DC you have to use either a full wave bridge or four diodes, some capacitors and a resistor to smooth the rectified AC.

The three pin regulator is a good way to go for smooth and noise free DC.  (you still need everything mentioned above)

I will go that way if DC is better then AC.

Can you make a small plan and part list to do this with the regulator and how to proceed for the voltage adjustment in the final stage.

Thanks again,

 

[Dobs]

Yes, no, maybe?

 

[Grainger49]

Yes, DC is better, lower noised, than AC.  I can't give you a schematic and parts list because I haven't done that.  You will need to get that from someone else.

Feed the supply from a 6.3 to 7V transformer winding.  You will need 4 diodes, UF4007 are fine, Cree soft recovery diodes are better.  You will need two 1000uF 16V capacitors and a 100 ohm 1/2 watt resistor.

I suspect that there are fixed voltage regulators for 6.3V, certainly 6V and rated at 1.5A minimum 2A is better.  A fixed regulator has three pins and puts out the specified voltage with a little of the input voltage wasted.  One pin is the input, one the output and the other is the "reference" pin.  That is attached to the voltage you want to regulate to by resistors.  I believe it is grounded when you are using a fixed regulator chip.

With 6.3V AC rectified and filtered you get a little more than 6.3V DC and the regulator wastes some of that voltage in the regulation process.  There are also variable output regulators that you can set up to put out any voltage you want. 

That is the best I can give you.  Maybe others might give more specifics if you want to start a thread in Tech Topics for a Seduction regulated heater supply.

 

[Dobs]

Ok, super!

Thread started here: http://www.bottlehead.com/smf/index.php/topic,1822.0.html

 

[Grainger49]

Bumped to include Reduction in the title.