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is orange wire on electraprint choke for b+end?

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Posted on May 15, 2017 at 01:45:02
amnesiac
Audiophile

Posts: 717
Joined: August 21, 2002
 I have lost paperwork again. I just want to be sure. its a plate choke blue and orange leads. orange makes the most sense. my new 45 preamp is nearly done.

 

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RE: is orange wire on electraprint choke for b+end?, posted on May 15, 2017 at 07:15:23
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Hi amnesiac,

I don't know the color-coding answer to your question, but here are some links that lead to some lengthy discussions on determining which end to what for choke connection based on which terminal has the dot.

Hope this helps,

caffeinator

 

RE: is orange wire on electraprint choke for b+end?, posted on May 15, 2017 at 11:16:41
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009
 My first thought was that surely it makes no difference. But on reflection, I suppose there might be a small difference between the effective capacitance to ground, and therefore one would prefer to have the end with the smaller capacitance connected to the anode. I suppose that would be the end of the winding that is on the outside, so to speak. Whether the difference is enough to matter is another question. Maybe you can see by inspection of the choke which end is outermost?

I suppose another possible consideration is that the B+ end just sits at a steady voltage, whereas the anode end will swing above B+ as well as below. Thus for that reason also, the end with the greater physical separation from the core might be the better choice for the anode end, since the risk of electrical breakdown would presumably be a bit less.

Are these the reasons why one might care about the choice of ends?

Chris

 

RE: is orange wire on electraprint choke for b+end?, posted on May 17, 2017 at 04:01:21
amnesiac
Audiophile

Posts: 717
Joined: August 21, 2002
 now your confusing me ha ha. I just assumed electraprint would of had a preferred phase. I didn't think of adding phase into the search either. For the record pale blue is the outside and orange is on the inside of the core which is connected to the b+ where it can stay for now. volts are going to be low. I want to run them super conservatively unless they sound too dull. I usually assume the reder or orange to mean the higher voltage or b+ end

 

RE: is orange wire on electraprint choke for b+end?, posted on May 17, 2017 at 07:43:29
dave slagle
Manufacturer

Posts: 5430
Location: NYC
Joined: April 27, 2001
 "standard" wiring color code has Red=B+ and Blue= Plate.

The wiring direction does matter and is best tested in circuit. Chances are the differences in capacitance we are talking about will not show up in most cases until 100Khz+ and it only becomes important when you get to the higher Rp tubes where choke loading is a dubious practice anyways. There is a good reason you don't see choke loaded 12AX7's and the lack of inductance isn't the problem. Take an amp designed to drive horns from 1Khz up. A -1dB point of 100hz would be adequate and require a 250hy 2ma choke which isn't a tough order for the low end... however given the 80K source impedance it is the top end that becomes hugely problematic and flat to 20Khz with a plate choke is a task. When you consider given a 80K source that the capacitance of a typical scope probe is -1dB at 6khz the situation becomes very real. Moving the the 10X setting on the probe will buy you a -1dB point above 20Khz (I just measured 27Khz) which is flirting with the edge of acceptability. Now understand that this is just the test setup and we are talking 15pf of probe capacitance. Now it is easy to see how the phase of the choke shifting capacitance around can move a -1dB point 10Khz one way or the other. Even grounding the frame of the choke has a marked effect as the source impedance goes up.

dave

 

RE: is orange wire on electraprint choke for b+end?, posted on May 17, 2017 at 08:20:13
amnesiac
Audiophile

Posts: 717
Joined: August 21, 2002
 yea I plan to test every trans and chokes in the preamp once finished. I started testing them before I started but problem my old velleman scope is ide plugs and my old workshop pc started crashing so I have to wait until I get a usb scope.

 

RE: is orange wire on electraprint choke for b+end?, posted on May 20, 2017 at 02:08:59
awsjr
Audiophile

Posts: 235
Location: Austin, Tejas
Joined: November 30, 2006
 the Welborne amps that use electra print chokes (drd 300b, 2A3 etc) with blue & orange wires the orange goes to ground and the blue to the plate

 

RE: is orange wire on electraprint choke for b+end?, posted on May 20, 2017 at 02:16:39
awsjr
Audiophile

Posts: 235
Location: Austin, Tejas
Joined: November 30, 2006



 

RE: is orange wire on electraprint choke for b+end?, posted on May 20, 2017 at 22:14:06
amnesiac
Audiophile

Posts: 717
Joined: August 21, 2002
 ok thx I got blue to plate and I did buy these from A guy that bought them for a drd.

 

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