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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Analog Metric grounded grid preamp kit

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sharpi31

Member
2005-10-20 12:57 pm
I've ordered this kit from Analog Metric:

Grounded Grid preamp kit

This is my first attempt at a valve-based component (I've done lots of class-t amps, gainclones, dacs etc.).

I plan on changing the coupling caps to obbligatos. I also have some 100uF/1000V Russian metallized paper caps which could be used for the PSU. Would this be a worthwhile upgrade over electrolytics?

The Russian caps are huge and would be tricky to house, but I'm happy to do this if they will be the better option.

Thanks in advance & happy New Year :)
 
Is this design actually licensed from the designer or is it just stolen?

edit: After poking around, it appears that this outfit is stealing trademarks and designs from a variety of sources. I would encourage people NOT to do any business with them. It's immoral, and given the appearance of the stuff, probably not very smart, either.
 
It is indeed a blatant copy, including theft of trademarks; to make it worse, they also used the name of the guy they're stealing from to promote this.

I'm sorry, I won't help you with this and I hope that no-one else on this forum does, either. I'm no big fan of the designer, but he doesn't deserve to be ripped off and I won't help in the process.
 
FWIW...

I purchased one of these from a seller on greEdBay about 3-4 years ago (not knowing what it was – blatant piracy, copyright infringement, etc). I think I paid somewhere around 45.00 us for it – it was basically complete minus a chassis and potentiometer. Well once I got it I realized what it was….and dropped it in my parts box - no real loss based on the price I paid.

A few years later ….probably around the time of this thread…

I was recently going through my parts (clearing some things out etc) and ran across it….I hooked it up and it sounded really good, so I decided to give it a go and see what happens. I changed a few capacitors (coupling capacitors – used Amp Ohm FP-CA-AU 630VDC – 5% tolerance), added a good quality pot, a Grayhill selector switch, some nice silver wire, and some Dayton Audio RCA connectors. Finally I built a nice wooden box for it (not quite complete) and stuck it all together. The results of this “parts box preamp” were pretty amazing. After the chassis is cleaned up and a few finishing touches are added I think this will make a nice little (if not cheap) preamp.

I do however want to stress that I do not claim anything on this project….because of the issues with AnalogMetric/DIY Zone and their blatant piracy of so many great products. So please do not flame me, I am just a lowly DIY’er trying to get good sound out of the stuff I have on hand.

I hope that I have not offended anyone by doing this…if I have…I apologize.
Wayne
 

jbarale

Member
2010-01-21 2:20 pm
Negative feedback

Sorry to be out of time. But these projects are models discontinued by their manufacturers, so they are already released.
Proof of this is that all preamplifier circuits have high doses of negative global feedback, increasingly disused because of the harmfulness that results for the sound
 
Sorry to be out of time. But these projects are models discontinued by their manufacturers, so they are already released.
Proof of this is that all preamplifier circuits have high doses of negative global feedback, increasingly disused because of the harmfulness that results for the sound

Too late: the myth about harmfullness of negative feedback is already obsoleted.
 
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