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Old 1st February 2012, 12:23 PM   #7171
merlin el mago is offline merlin el mago
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I want to increase the gain +6 dBs, I'm using this schematic without C10 so instead 63dBs I have 57dBs, wich one will be a better solution:

-Partridge 977 1:6 15dBs step up, what I have to do about load resistor? I have to take of 150R from Simplistic & adding a resistor at the ouput of the step up, I don't know how calculate?

-Salas active pre-pre 1:10 20dBs, I don't know hows but I think it need to be modified because will be connected to MC instead a MM and also is the load resistor, I don't know how calculate?

-Make a new active pre-pre for only +6 dBs?

-Using Sowter 9395 autoformer attenuator and utilize its +6 dB gain tap as suggested to Kent?
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File Type: gif prepre Salas x10 gain.gif (2.6 KB, 248 views)
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Old 1st February 2012, 03:39 PM   #7172
Salas is offline Salas  Greece
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What I suggested to Kent was for output volume control straight to his amp along with gain at output. Useless at input side.

For 63dB you make the pre-pre and himc chained together. No individual circuit or pre-pre to 57dB matches. Unless you can compromise to a capacitor bypass on the one you already got.
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Old 1st February 2012, 04:04 PM   #7173
merlin el mago is offline merlin el mago
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Thanks I supposed can't be possible, I left the Partridge step up for Valve Itch, fortunately I have two R-Core 24-0-24 120VA without use
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Old 1st February 2012, 04:07 PM   #7174
Salas is offline Salas  Greece
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Can you measure their real secondary value on 230V mains? Want to know for another project. Thanks.
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Old 1st February 2012, 04:08 PM   #7175
merlin el mago is offline merlin el mago
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Without load? 60VA or 120VA?

Last edited by merlin el mago; 1st February 2012 at 04:11 PM.
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Old 1st February 2012, 04:14 PM   #7176
merlin el mago is offline merlin el mago
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Without load only one secondary 0-24V I read 26,2VAC
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Old 1st February 2012, 04:39 PM   #7177
Salas is offline Salas  Greece
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OK thanks. Is that the 120VA model in pictures?
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Old 1st February 2012, 09:39 PM   #7178
merlin el mago is offline merlin el mago
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Yes.
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Old 1st February 2012, 10:56 PM   #7179
kstlfido is offline kstlfido  United States
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Thanks Salas and Merlin for the info.

At 134.33 each for the Sowter 9395, it's a bit rich for my frugal budget. It would be a nice all-in-one solution though.

I was going to use the Lightspeed LDR attenuator, as I already have built it.

I will try the 1000u source bypass cap across R2 on Q1 and see how it changes the sound.. I'll need to get a Simlic or Muse at that value.

Cheers- Kent
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Old 1st February 2012, 11:27 PM   #7180
Salas is offline Salas  Greece
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Alright.
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