Paramour I Power Supply Resistor /Choke

[leonlicer]

Hi everybody,

it has been years since my last writing. I was just listening to the music and not thinking on electronic. I have a pair of Paramours I. At home I have found a pair of toroidal chokes 20 H,  115 Ohm I have no data for mA. I wonder If I could use them as a replacement for a power supply resistor. To have the right voltage on B6 I would need to replace one or both 499 ohm resistors on CS4 with higher value.
Since I am not an electronic guy I am asking you guys would it work that way or not? If yes which resistors should I use?

thanks in advance,
Leon

 

[Grainger49]

Leon,

Edit: Ok, I got it now.  You want to put a plate choke in the power supply.  Not knowing the current might be a problem.  If you can find out or know the wire size of the windings that would help.
I don't think a change in voltage will necessitate changing the R1 value.  That is the "current setting" resistor.

I, too, have Paramour 1s.  I have upgraded the iron with MQ output and plate choke.  The stock plate choke went between the two 47uF caps in the power supply replacing the resistor there.  The DC resistance of the stock plate choke was less than the resistor it replaced.

 

[leonlicer]

Thank you for your reply. Actually I think the old choke DC resistance is 270 Ohm which is the same as the power supply resistor. The voltage on B6 should be 155 - 200 V.  I read the voltage higher than 200 V is not good.
I dont know if lower DC resistance in power supply influences only on the B6 voltage or  is there also something else??
I guess I can regulate the B6 voltage with the resistor on CS4 or is there some other way. Excuse my ignorance but I am a Furniture guy not beiing very strong in electronics.

I have not seen anybody using a toroidal choke in Paramour. Why is that? more expensive?, not good?...

Leon

 

[Grainger49]

If your Paramour worked, and had the right voltage to start with you shouldn't get higher after the swap.  Well, maybe a few volts.

Is it possible that the two tubes are not conducting properly?  What is the... calling up my schematic... what is the voltage on pins 8 and 6 of the 12AT7 and pins 1 or 4 and 2 of the 2A3?  This will say if the tubes are conducting as expected.  

To answer your question, yes increasing the resistance in the power supply wastes a little more voltage as lowering the value increases the voltage going to the driver/C4S and the output tube.  The C4S will handle the increase without sending it to the driver tube.

 

[leonlicer]

The B8 voltage is 1.9 and B6 198 V. For A1 and A4 I think is 58.6  (it should be 60 right?) A2 not sure (writing in bed to lazy to stand up and check).
I will try to change the resistor (270 ohm) with  the choke  115 ohm. Nothing lethal can happen ? 

 

[Grainger49]

The voltages on the driver are fine.  That tube is working well.  The same goes for the 2A3.  Voltages within 15% are considered good. 

The 270 ohm resistance is not critical.  If the current capability is exceeded the magic smoke comes out.  If that happens you want to put back the resistors.

 

[leonlicer]

No smoke. It works though there is not a big difference. A little lower level of hum and a bit better bass, that,s all. need to try double iron version. The problem is that Speco is not producing the old (Yellow) version of output transformer. The new one (Blue) is a joke, also the tabs are not the same 1 W instead 1,25 and 0,5 W instead of 0,625.
Could somebody suggest an alternative (not Magnequest, I can not afford it).

thank you
Leon

 

[Grainger49]

Leon,

Do you need a Speco transformer as an upgrade?  I take it your Paramours didn't come with the Speco, right?  I have a pair of them that I took off of my Paramours when I upgraded.  They would be yours for the cost of shipping if that is what you are doing.

Grainger

 

[Paul Joppa]

Grainger, a long time ago I had suggested paralleling two Specos for each channel (with suitable changes to the taps). This gave them another half octave of bass power handling, and was very cost effective when the transformers were still available. I'm pretty sure that's what leonlicer is talking about.

It's still in the plans to offer the new SEX/Stereomour iron for upgrading SEX 2.0 kits; when that happens the same iron is suitable for use in Paramour I and II. I don't expect there will be a manual or anything, but the parts should become available at that time. But it won't be cheap; more on a par with the Magnequest iron than the Speco!

 

[Grainger49]

Ok, so my offer is still good if he wants my pair.

 

[leonlicer]

Yes, that,s what I have in mind, to double the output transformer. If you mean it Grainger I will gladly take them. The shipping will be high because I live in Slovenia (EU) please check out the cost and let me know. Can I pay with PayPal ?



Thank you, Leon

 

[Grainger49]

Leon,

Yes, I'm serious.  I cut and pasted the address and PMd it to myself.  Now "Modify" your post to delete your address.  I am uncomfortable with personal information on the net.   Well, my real name is in my signature but I keep my address and email private.

I'll pack them and get the quote from the USPS. 

 

[leonlicer]

I just did it. Thank you.

 

[Grainger49]

Leon,

I finally found them today.  That is a tribute to how much S.... Stuff I have in my work room.  I'm  going to wrap them in bubble wrap and see what I can do about postage.

I'll be in touch.

 

[leonlicer]

Thank you Grainger you are very kind. I read with two OPT everything is better. I can hardly wait to install them.
There is one more question about connection of the transformers. I plan to connect primaries (1,25 W tabs) in series and also 8 ohm secondaries in series (for 8 ohm speakers- Fostex FE206E) like Voltseconds suggested. Or is there a better way? Could you or somebody else comment on that??

Thank you, Leon

 

[Grainger49]

I wouldn't second guess VoltSecond.  He is younger than I am (hears better) and is an excellent engineer as well.  So I'm saying go with his suggestion.  I upgraded to MQ iron so I have no experience with the double output transformer configuration.  

 

[Paul Joppa]

The best is to parallel the 0.635W primaries. This uses the full winding. The secondaries can be connected in several ways:

Parallel the 8 ohm secondaries for a 4 ohm load

Put the 4 ohm taps in series for an 8 ohm load

Put the 8 ohm taps in series for a 16 ohm load

 

[leonlicer]

Thank you Paul, I have now a 1,5 uF Jantzen supreme coupling cap,  I think I read somewhere I need to increase it to 4,7 uF for a double iron. If I connect a 3,3 uF in parallel ?? do I get a 4,8 uF?  (I have a pair of 3,3 uF Solen FC caps at home) or would be better to have one with higher value?

 

[Grainger49]

Leon,

Yes, caps add in parallel.

 

[Paul Joppa]

I have posted elsewhere about parafeed cap values. They depend on the plate choke value, with some adjustments for the specific situation. For the Paramours into a 4K load (which is the double transformer as I described it) and using the original 10 henry choke, 1.5uF is just about right.

The original Paramour used 3.3uF, which extended the deep bass for small signals but limited the power handling of the tube in the deep bass. I thought that was OK because the single transformer also had deep bass power limitations. With the double transformer (and assuming you have retained the stock 10 henry choke) the transformer can handle the power so I would use the smaller cap (1.5uF, more or less) so that the tube is able to deliver all the power the transformer can handle.

If you decide to replace the plate chokes with the 20H toroids, and replace the power supply resistor with the original 10H plate chokes, then the best capacitance would be twice as large, something nearer 3uF.

But in any case, it is always worth experimenting. Try the 1.5, try the 3.3 (original), try both in parallel. The quality of the cap will affect the midrange and treble; the capacitance will affect the bass (especially deep bass). When the deep bass sounds best, you can explore better caps in that value to optimize the mids and treble.