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1:16 SUT: LL1933 or LL1943?

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Posted on January 23, 2017 at 15:03:32
Jarek
Audiophile

Posts: 4
Joined: January 23, 2017
Dear all,

I'm looking for a high bandwith SUT for LOMC 0.2mV/2R (FR-7f). I figured out 1:16 will give me enough gain. I'd like to try Permalloy, which leaves me with 2 possibilities:

(1) Parallel-Series LL1933
(2) Series-Series LL1943

In your opinion, which one would be preferable and why?

Thank you in advance,
jarek


 

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RE: 1:16 SUT: LL1933 or LL1943?, posted on January 26, 2017 at 11:40:42
Jarek
Audiophile

Posts: 4
Joined: January 23, 2017
Nobody has ever faced such a question nor made comparisons? Kevin :)?

Cheers,
Jarek

 

RE: 1:16 SUT: LL1933 or LL1943?, posted on January 26, 2017 at 11:57:50
KevinC
Manufacturer

Posts: 2911
Location: NC
Joined: April 19, 2001
I haven't made the comparison. Given that in the 24 dB step-up connection that same core is used, the same transformer structure, and the same wire is used, I suspect that any difference is going to be pretty hard to hear. I can't say more than that, not having actually made the comparison.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: 1:16 SUT: LL1933 or LL1943?, posted on January 26, 2017 at 14:17:38
Jarek
Audiophile

Posts: 4
Joined: January 23, 2017
I was trying to make an educated guess and it seems that electrically both alternatives look close, like Kevin says:

1) LF: Assuming the same core and wire on both, since the DCR of the seconadries is the same@85R and the primary DCR of 1933 is roughly 2x that of 1943, the primary coils of 1933 have 2x the turns of 1943. This gives 4x the inductance. Divided by 2 due to the paralelling, it equals the primary inductance of 1943 primary coils in series.

2) HF: The capacitance is probably more imp. than the leakage inductance for SUT's. Each primary coil of 1933 would probably have the cap. = 1/2 of that of 1943 (due to 2x turns giving roughly 2x number of layers). So the cap. of the parallel 1933 primary coils is 2x cap. of the series 1943 primary coils. The total cap. at the primary is that plus the reflected secondary cap. which is the same for both SUTs.

So if all that makes sense it looks like series-series 1943 will present a bit less capacitance to the cart, while the primary inductances are roughly the same. I tried contacting Per, let's see if he finds time to reply and give his view. Some people (e.g. Thomas Mayer), seem to prefer 1933 over 1943 but I'm not sure in which configuration.

Cheers,
jarek

 

RE: 1:16 SUT: LL1933 or LL1943?, posted on January 31, 2017 at 05:33:32
Jarek
Audiophile

Posts: 4
Joined: January 23, 2017
Per answered my mail (thank you very much!), confirming my above assessments: in those configurations both transformers are basically the same. Case closed :)

Cheers,
Jarek

 

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