JBB
Active member
ruffrecords said:Still puzzled by the quoted -130dBu EIN figure.
Thank you. Fixed.
ruffrecords said:Still puzzled by the quoted -130dBu EIN figure.
momomo391 said:Can you show or explain how the potentiometers and switched hook up to the pcb in the layout?
cvea said:I have some drip pcb boards for sale:
2 Ultra 47 - $200 USD each plus shipping.
1 Opto 6 (fast & slow drip T4B included) $350 USD plus shipping.
1 EQP1A $250 USD plus shipping.
I have to pay school so I will have to leave these projects for later
Winetree said:Plus shipping?
Tired of asking. List your location in your profile
cvea said:I have some drip pcb boards for sale:
2 Ultra 47 - $200 USD each plus shipping.
1 Opto 6 (fast & slow drip T4B included) $350 USD plus shipping.
1 EQP1A $250 USD plus shipping.
I have to pay school so I will have to leave these projects for later
Winetree said:Plus shipping?
Tired of asking. List your location in your profile
cvea said:I have some drip pcb boards for sale:
2 Ultra 47 - $200 USD each plus shipping.
1 Opto 6 (fast & slow drip T4B included) $350 USD plus shipping.
1 EQP1A $250 USD plus shipping.
I have to pay school so I will have to leave these projects for later
$15 to ship a PCB? Isn't that just a flat envelope with a little stuffing? $5 max?cvea said:Sorry guys. I just updated my profile. I am located at Massachusetts so I believe shipping to California is around $15 or so.
My3gger said:Original or Drip's psu could be improved and simplified, while retaining sound of preamp, have less work with it, specifications can be better, etc.
Why not simply use zeners as voltage reference instead of OA2s, this are known to cause problems for many builders, they take a lot of space, availability on the long run is questionable, etc. Real regulators could be used too, although zeners, maybe with cap multiplier make for a good HT psu. Replacing GZ34 or 6X4 for diode bridges doesn't do any harm to the sound. Fast, low drop diodes have some advantages over 1N4007s, although differences are small, i like them because heater LDO regulators need smaller heatsinks.
Ruffrecords posted schematic for simple phantom psu with TL783, 2W resistor takes care of minimum load for regulator to function on its own, so it is easy one.
We see wrong attenuator at the input of it all the time, output doesn't need to be 200 ohms either and trick for making 200 ohms from 600 ohms seems like not the best idea. How can phantom work properly with T attenuator, it needs to be U, so one side doesn't have extra resistance. Output att. isn't needed with preamps like this because NFB causes sudden distortion which doesn't sound too nice.
I see no reason for the meter either and it needs buffer to function properly.
Tests show that 40 and 46dB positions are good to have, sound changes quite a bit from one to another. 34dB position gets no use here, it doesn't sound as good as the other two
All of this makes for easier, cheaper, more reliable and higher performance preamp of this type, along many others. G9's psu is pretty easy to make too, those back to back transformers can be replaced to single item.
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