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Pyramid SEA-2500X Preamp voltage output mod

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JoseMR
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Pyramid SEA-2500X Preamp voltage output mod

#1

Post by JoseMR » 21 Sep 2016 01:32

Hello, I've purchased a cheap Pyramid SEA-2500X audio preamplifier based on the Amazon reviews until I can afford an Stereophile grade one such as Parasound Halo P5, the default specifications claim that this preamp have a input sensitivity of 150mV(line level) and a output of 500mV(0.5 Volts) which is absolutely too low for any studio/pro audio preamp, also during my test this preamp even attenuated the audio signal of my tuner, though I bough it to actually play with and modify it, since the modification changes where very simple than I expected, yet extremely notorious and without sound quality sacrifice, I decided to post a short how-to to make this preamp to actually work, after this simple modification this preamp will be able to drive your Hi-Fi stereo amplifier without turning the volume knob to high to reach desired output levels, thus reducing distortion and clipping.

Internal preamplifier view:
Image

Now the simple mod:
100_6647-Mod.jpg
Change the R43 and R44 47K ohm resistors with 1K ohm resistors and voila, enjoy the new higher output preamp voltage(2~3 volts approx).

Note: This mod are intended for electronics experienced users, please don't try this by yourself if you don't have basic experience with electronics/electrics.

Regards
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Last edited by JoseMR on 07 Jul 2018 08:49, edited 1 time in total.
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Jack Foobar
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Re: Pyramid SEA-2500X Preamp voltage output mod

#2

Post by Jack Foobar » 28 Sep 2016 04:03

That looks like a board design from the 1980's. I think I had a kit to make that exact board when I was a teenager.

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JoseMR
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Re: Pyramid SEA-2500X Preamp voltage output mod

#3

Post by JoseMR » 28 Sep 2016 05:09

Hi Jack Foobar, that's right, this cheap preamplifiers are based on a very simple circuit design actually, though there are several designs around the net, yet very similar to this low cost units Gemini, Pyramid/Pyle, however all this budget brands are similar.

Regards
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