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Old 10th February 2006, 09:47 PM   #1
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Default Decisions, Decisions - Help me select iron

I've done my searches and I know this has been beaten to death, but please bear with me.

This is my first DIY build and decided on the JELabs Delux variant by Derek Walton (Mk2).

Rather than using the $$$ Plitron components, I'd like to build this amp with decent, cheaper components. Please keep in mind I won't mind spending a little extra $$ for better components.

Power supply circuit:

Click the image to open in full size.

I will probably use the Angela Universal mains TX, unless there are other similarly priced units out there that are of better quality/value.

I've e-mailed Derek and he suggested the 20H choke was overkill and suggested 2-10H (min 90ma) chokes.

My chices are (in no particular order):

1) James JS-10-250S, 10H @ 250mA, 65 ohms ($85/piece)
2) Hammond 193J 10H, 200ma, 82 ohms, 800VDC($40/piece)
or any of the following 10H Lundahl chokes
3) LL1638 / 10H 10 H 150 mA 215 mA 36 ohms
4) LL1685 / 160mA 10 H 160 mA 230 mA 130 ohms
5) LL1673 / 10H 10 H 200 mA 290 mA 60 ohms

Any help here would be appreciated.


Signal circuit:

Click the image to open in full size.

I pretty much decided on either the James or One Electron output tx, but don't know which one to use and/or why:

James units:

JS-6123H 120mA 2.5K/3.5K/5K 20W 15Hz-70KHz-2dB 2A3 / 300B / 6V6 3.2kg

JS-6132H 120mA 2.5K 30W 15Hz-90KHz-2dB 300B / 6L6 / 2A3 4.8kg

JS-6133H 120mA 3.5K 30W 15Hz-90KHz-2dB 300B / 12E1 / EL34 4.8kg

JS-6135H 120mA 3.5K/5K/7K 30W 15Hz-45KHz-2dB 300B / 211 / 845 5kg

One Electron:

UBT-1 1600 ohms 4, 8, 16 ohms 160 mA 15 W

UBT-2 4800 ohms 4, 8, 16 ohms 110 mA 15 W

UBT-3 3000 ohms 4, 8, 16 ohms 110 mA 15 W

Thanks for any help and/or other suggestions.
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Old 10th February 2006, 10:22 PM   #2
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Hammond 158M choke, which meets your requirements, is less than $18 at parts connexion. It lacks end bells.
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Old 11th February 2006, 01:33 AM   #3
Sherman is offline Sherman  United States
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Default OPT Opinion

I can't comment on the One Electron OPT but I have James 6123HS in my SE KT88 monoblocks and they sound great. I'm running 82mA through them.

The fit and finish is top notch as well. When I purchased mine the only color available was a sort of 'champagne' metallic. Now I believe you can also get black.

On top of all that the price is right, only slightly more than Hammond 1628SE.
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Old 11th February 2006, 03:14 AM   #4
arnoldc is offline arnoldc  Philippines
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I own the 193J- it's huge. I used it on my JE Labs 300B (you can see my amp at derek's site).

I will run a 300B with 5K load and would go for the 6123HS myself.
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Old 11th February 2006, 07:25 PM   #5
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Thanks for the responses so far.

But, is a choke a choke a choke in this instance? Is there an audio quality difference between the different chokes mentioned? Or would my funds be better spent on higher quality OPT's? I know this project isnít going to be inexpensive and I don't mind spending the a little more for something sonically better (but don't want to go nuts either).

Regarding the James OPT's, why is the JS-6123H better suited than the JS-6133H? The JS-6133H has a higher wattage, and larger frequency range. Is it because 6123 is more flexible for possible projects down the road (2.5K/3.5K/5K)? Is the additional wattage offered by the 6133 not needed for 300B output?

Just a newb trying to learn......

Thanks for bandwidth.
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Old 12th February 2006, 03:20 PM   #6
Sherman is offline Sherman  United States
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The 6133 and 6123 are very similar with the 6123, as you stated, having a bit more flexibility. It is also slightly less expensive. I personally doubt you would hear a difference between them.

As for wattage rating- with a SE 300B you will get 7-9 watts. You don't need a 30W OPT (or even a 25W OPT).

One thing to remember when selecting an OPT for SE use is current capability. Having excess current capability is more important than having excess wattage rating and both the James OPTs you are looking at have 120mA current ratings.
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Old 13th February 2006, 08:22 PM   #7
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Sherman et all,

Thank you.
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Old 14th February 2006, 12:05 AM   #8
amperex is offline amperex  United States
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Hammond power transformers & chokes are good items plus inexpensive. James, Electron One or MagnaQuest audio transformers are fine business.
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