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Old 27th June 2012, 09:24 AM   #1
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Default Tubelab SE choke

Hi all, I am just doing a little research into parts for a SE build. I am wondering if this choke will do the trick https://www.edcorusa.com/p/782/cxc125-10h-200ma
It will be put into this circuit TubelabSE (look a the power supply schematic down the page. I would be put in place of R4.

Cheers Luke
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Old 27th June 2012, 09:39 AM   #2
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Howdy Luke,

Yes, the choke you want to use will work. Note that its DC resistance of 75 ohms is exactly half of the value of R4 as shown on the schematic. This means that you'll likely have a higher B+ voltage, which may or may not be a problem depending on the output tubes used.

-Larry
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Old 27th June 2012, 09:55 AM   #3
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With the choke in the circuit you can adjust the B+ by changing the value of c4. My TSE ended up using a small cap for c4.
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Old 27th June 2012, 09:58 AM   #4
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Right, I will be using 300B tubes the PT is a 372 JX as recommended by George in another post. it puts out 600v CT

cheers
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Old 27th June 2012, 10:05 AM   #5
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Of course evanc, I overlooked that detail. Actually I am not sure how that works yet, that is some reading that must be attended.

thanks
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Old 27th June 2012, 06:09 PM   #6
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Quote:
Originally Posted by magnetman View Post
Of course evanc, I overlooked that detail. Actually I am not sure how that works yet, that is some reading that must be attended.

thanks

Magnetman: The short answer is in a CLC supply, you can reduce the B+ voltage by reducing the value of the first cap. Typically the voltage doesn't change much until you get the first cap value below about 10uf or so, sometimes less than that. The way I look at it is that there is a spectrum of B+ values between an LC supply (B+ is approx 90% of your transformer secondary AC voltage) to CLC (B+ is approx 141% of transformer secondary voltage). When that first cap value starts getting small, you are moving toward an LC supply, sort of "pseudo-LC".

You can also dial in the B+ a bit with different rectifiers, as they have different forward voltage drops, like substituting a 5U4 for the 5AR4, etc.

Download and play with PSUDII from Duncan amps, it's a great way to see what B+ voltage you'll end up with (as well as a few other things) based on the PS topology and components selected.
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Old 28th June 2012, 09:17 AM   #7
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Boywonder thank you for your explanation and software tip. I will download it as soon as i get a windows interface for my mac. It makes a little more sense now though. Fascinating stuff.

cheers
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Old 28th June 2012, 03:21 PM   #8
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Magnetman: Here is the schematic that you want to model in PSUD. This looks fine for a Tubelab SE 300B. In actuality, your B+ will probably be a little higher since hammonds tend to run high on voltage and your transformer is spec'd at 220ma, so it will be loafing along at half throttle.

The assumptions that I made here are 60ma per 300B, and 12ma per 5842 for a total of 120ma+24ma=144ma. You can play around with different rectifiers, more (or less) idle current for the 300B's, etc. I left the resistance of the transformer at the default settings of 31 ohms; you can dial things in a bit closer by measuring from one end to the CT and using the actual value.

Once you load the program, you change things by right-clicking on the components, or on each stage.
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File Type: jpg Tubelab SE PSUD.jpg (144.2 KB, 282 views)

Last edited by boywonder; 28th June 2012 at 03:23 PM.
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Old 1st July 2012, 03:43 AM   #9
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Sorry boywonder, I have been trying to get a pc simulator to work on the mac, i think i will have to cough up for a commercial product. Thankyou for the program. I am super keyed up to try all this out.

cheers
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Old 1st July 2012, 05:38 AM   #10
tomchr is online now tomchr  United States
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You can also dial in the B+ voltage by adding some resistance in series with the inductor. I'd prefer that over changing capacitors as the latter will change the ripple on the supply as well.

OT: Free software for running Windoze on a Mac, look at VirtualBox. It's not as good as VMware (IMO), but it does the job and is free.

~Tom
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