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Old 21st May 2016, 05:17 AM   #1
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Default Would there be any harm using 10K OPT for 45 tubes?

I have a pair Transcendar 10K/600R output transformers that I plan to use for a 45 preamp. Normally people use 5K ones for 45 tubes. My question is would there be any disadvantage of using 10K ones?

Also have a Harman Kardon XT-3 Microphone transformers that I am thinking of using as stepup input transformers. Could anyone suggest the best configuration to make the best use of these transformers that I currently have?

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Old 21st May 2016, 07:14 AM   #2
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Nothing wrong, just twice lower gain, but also cleaner the sound. However, it must be one with an air gap, for DC bias.

Microphone input transformers are very different. Some may saturate on line level voltages on low frequencies. Well, most of them...
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Old 21st May 2016, 07:27 AM   #3
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two completely different questions-

first question is very much answered. I would prefer an OPT with lower primary impedance - you might find 10k weak on the Bass with 45 (like I did).

for the Harmon Kardon XT-3 do you mean step-up for MC phono? That is what I would use them for, depending on the cartridge...

Last edited by soulmerchant; 21st May 2016 at 07:38 AM.
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Old 21st May 2016, 07:30 AM   #4
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Also.. some TV sweep tubes might be a nice match your 10K:600R OPT too.
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Old 21st May 2016, 04:53 PM   #5
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If your power amp has an input impedance of say 100k then the primary load will be a lot more than 10k. Just set a fixed resistance on the secondary of 300 ohms and you will have your 5k primary load with any power amp hooked up
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Old 22nd May 2016, 03:20 PM   #6
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Quote:
Originally Posted by Wavebourn View Post
Nothing wrong, just twice lower gain, but also cleaner the sound. However, it must be one with an air gap, for DC bias.
10k to 600 ohm is 4.08 : 1 (winding/voltage ratio)
5k to 600 ohm is 2.89 : 1.

So not twice lower gain.
Actually the difference is only 3 dB.
More important with these transformers to have enough primary inductance.

Last edited by pieter t; 22nd May 2016 at 03:28 PM.
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Old 22nd May 2016, 09:26 PM   #7
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Quote:
Originally Posted by pieter t View Post
10k to 600 ohm is 4.08 : 1 (winding/voltage ratio)
5k to 600 ohm is 2.89 : 1.

So not twice lower gain.
Actually the difference is only 3 dB.
More important with these transformers to have enough primary inductance.
I know, Transformer Guru is not required to think about Ri of tubes...

;-)
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Old 22nd May 2016, 09:48 PM   #8
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Please explain....
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Old 22nd May 2016, 10:04 PM   #9
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Quote:
Originally Posted by pieter t View Post
Please explain....
I can't, you know everything.
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Old 22nd May 2016, 10:13 PM   #10
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Please stop with your personal remarks since you don't seem to have something to bring up.
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