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Old 26th April 2002, 09:31 PM   #1
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Question Anode choke question

Hi!

What about Lundahl LL 1668/25mA 100H as 5842 anode choke?

Thanks
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Old 27th April 2002, 04:54 AM   #2
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Specifications look OK.
I have used 70H/35mA choke with 5842. So 100H should be OK

Mohan
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Old 27th April 2002, 08:47 AM   #3
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Quote:
Originally posted by Mohan Varkey
Specifications look OK.
I have used 70H/35mA choke with 5842. So 100H should be OK

Mohan
Thanks.

I know there are many reasons why OPT-s sound different. But what about anode chokes? Is there something else than right inductance only?

Tõnu
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Old 27th April 2002, 09:23 AM   #4
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Tonu,
I do not have extensive experience with choke loads. I used it only once in a DC coupled design. The choke gave a good account of itself but I preferred a simple load resistor. This is because my brain tells me that the load impedance of a choke varies with frequency and so I developed a prejudice.

I know that capacitors also have resonant frequencies. But I do not view them with such prejudice. Perhaps, it is the cost factor. Why spend more than a few dollars for a good high stability anode resistor?

Now you know that my views are not unbiased.

Mohan
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Old 28th April 2002, 01:47 AM   #5
dice45 is offline dice45  Germany
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Tonu,

the Lundahl anode chokes are 1st choice. The value you have chosen should do fine.
My buddy Thomas Mayer (Vinylsavor) uses them and is very happy and i decided to use 4 of them in my fully differential preamp.

They do one thing: they present a very high, almost infinite load to the anode. So the tube runs at gain=µ. They do another thing: DC-wise they almost short the anode to its supply. In a differential circuit this makes enormous sense as you can get DC-coupling almost for free and not even the PS cap acts as hidden coupling cap. The well-defined DC potential of the anode gives a very stable biasing of the following stage's grid.

The first thing can be accomplished using a CCS, the 2nd not.

Sonically an anode choke has much of an OPT and seems to sound friendlier than a CCS.

My sonic prejudices are exactly inverse to Mohan's , i have done much cap testing and listening and much more prefer how chokes and trannies influence sonics.
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Bernhard
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Old 28th April 2002, 02:56 AM   #6
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If you haven't bought it yet, also look into the chokes Stevens and Billington sell. Reports I've heard are that they're quite good. I'm contemplating ordering a pair for a diff linestage, and depending on where you buy them from, they can be cheaper than the Lundahls.

http://www.stevens-billington.co.uk/pagehifi.htm (bottom of page)
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Old 28th April 2002, 04:21 AM   #7
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Those Stevens and Billington chokes are grid chokes, not anode chokes. They can't handle DC current.

Choke loads and constant-current sources are nice because they make the tube operate in a much more linear fashion.

Charlie
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Old 28th April 2002, 04:41 AM   #8
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Red face D'oh

I only saw them again late last night when I was 'thought experimenting' a couple of projects, and really should have been in bed. I do recall thinking how do they get 4000H out of them?

Sorry. Consciuosness before posting next time
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Old 28th April 2002, 08:00 PM   #9
dice45 is offline dice45  Germany
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Brett and all,

i frequently read concerns about Lundahl prices. IMO the price/quality relation of the Lundahl stuff is unbeatable.

I am not affiliated with Lundahl however, just convicend about their products.

There are some model numbers from Lundahl however which work not as terrific as the best ones ( best ones being LL1667/8, LL1660, LL1635, LL7901/2/3).
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Bernhard
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Old 29th April 2002, 01:04 AM   #10
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Hi Bernhard,

I have used Lundahl transformers before from their Pro range, mic and some line drivers, and have no doubts about recommending them. Very fine product at an excellent price, better than all the alternatives I've looked at such as Hammond, Bartolucci ($$$), Plitron ($$$), Handwound and the Japanese (big $$$) iron. They are even cheaper then the local winders can do. My mistake re the choke, the S&B being half the money but not equivalent, was merely a suggestion for Tonu perhaps to save some money. I find most diy-ers want the best, but try to do it as cheaply as possible.

What got me back into tubes after a long hiatus, was Lynn Olson's Amity: such an elegant cicuit, but it's high performance is very dependent on the transformers. I have all the tubes and parts for them, but not the Lundahls, as I can't see the point in having 20W with 105dB+ speakers. I'm now building something smaller based on triode 6BQ5s, but unfiortunately I will have to slum it ( ) and use Magnequests as Lundahl do nothing suitable. Pity, they were my preference. The other amp I looked at was Allen Wright's PP1, as I am part way throught an RTP, using LL1663's. Again, no need for 12W, and I like 6BQ5s better than 6CA7s. Allen is a great designer who's recognition nowhere near matches his ability.

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