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#26 pre amp
#26 pre amp
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Old 5th April 2011, 05:54 PM   #931
vgeorge is offline vgeorge  Greece
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#26 pre amp
-9v bias and 150v B+ is around 8mA on a 26 tube so I would prefer 135v, in order not to stess the 1660 at 5mA. If you use a SSHV and have the proper sinks, you can adjust easilly. I drop around 90v on mine. I used a plate choke and prefered the 1660 transformer. Mind you that I use 4:1 for the 1660.
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Old 5th April 2011, 07:58 PM   #932
dvb projekt is offline dvb projekt  Germany
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#26 pre amp
Does it make sense to use the amorph version of the Lundahl 1660?

BTW, i dont find any datasheet of the 5mA version.
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Old 5th April 2011, 08:02 PM   #933
andyjevans is offline andyjevans  United Kingdom
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The 5mA version does exist. As far as I know it's the same as the PP version - same gap.

andy
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Old 5th April 2011, 08:18 PM   #934
Vinylsavor is offline Vinylsavor  Germany
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Hi!

Quote:
Originally Posted by Bas Horneman View Post
How about the Lundahl 1680. a Replacement built for the UTC ls-2
I tried the 1680. I prefer the 1660 it sounds and measures better

Thomas
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Old 5th April 2011, 08:19 PM   #935
Vinylsavor is offline Vinylsavor  Germany
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Hi!

Quote:
Originally Posted by dvb-projekt View Post
Does it make sense to use the amorph version of the Lundahl 1660?
Matter of taste. I prefer the standard cores

Thomas
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Old 5th April 2011, 08:19 PM   #936
Vinylsavor is offline Vinylsavor  Germany
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Quote:
Originally Posted by andyjevans View Post
The 5mA version does exist. As far as I know it's the same as the PP version - same gap.
Correct!
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Old 5th April 2011, 08:44 PM   #937
dvb projekt is offline dvb projekt  Germany
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#26 pre amp
Quote:
Originally Posted by Vinylsavor View Post
Hi!



Matter of taste. I prefer the standard cores

Thomas
The 5mA or 10mA version?
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Old 5th April 2011, 08:52 PM   #938
Vinylsavor is offline Vinylsavor  Germany
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Hi!

I have not compared the different cores for all transformers and all currents.

If you intend to run the 26 at 5mA or less and you want to use the transformer only for the 26 linestage, go for the 5mA. If you want to experiment with higher currents or maybe want to try other tubes as well. The 10mA will still work well with the 26. I use the 10mA version in my linestage which can be switched between 26 and 801A. Since the 801A runs at around 10mA, I used the 10mA transformer. I mainly listen with the 801A anyways since I prefer it.

Thomas
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Old 5th April 2011, 10:56 PM   #939
Bas Horneman is offline Bas Horneman  Netherlands
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Quote:
I tried the 1680. I prefer the 1660 it sounds and measures better
Thanks. Good info to have.
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Old 8th April 2011, 06:00 PM   #940
Lauscher is offline Lauscher  Germany
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To Thomas and all others:
Have you tried the LL1692A as line output ?
The PP-Version with 5mA gap has 210Henry. This should be fine for the tube 26. The LL1660-PP has 290Henry.
I was comparing the data sheets of both transformers:
Both with a gap for 18mA in Connection Alt. Q in SE Line Output:
LL1660 Freq. Response: 11Hz - 35KHz
LL1692A Freq. Response: 10Hz - 55KHz
The LL1660 has 4.5 : 1 ratio and the LL1692A has 3.5 : 1 ratio. The 5mA gap version should have better Freq. Response than 18mA.
In this connection Alt. Q the LL1660 has a primary DCR = 1250 Ohm and the LL1692A has primary DCR = 690 Ohm.
On the site of K&K i have found, that the LL1692A has a resonance point that is moved up in higher frequency and has a lower amplitude compared to LL1660. No comment about sound.
What transformer should i use ?
Thank you. Johann
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