I want to build the OddWatt Riaa Phonograph Preamplifier Groovewatt.
I have some "unknowns" in the schematic.
No experience with MC cardridges, but I want to build it to be ready.
In het schematics, there are 4 resistors, which can be added to change the load value. (RED)
Second, what is the MC jumper which add 100pF used for ? When do I need this ?
Kind regards,
I have some "unknowns" in the schematic.
No experience with MC cardridges, but I want to build it to be ready.
In het schematics, there are 4 resistors, which can be added to change the load value. (RED)
Second, what is the MC jumper which add 100pF used for ? When do I need this ?
Kind regards,
Attachments
Load resistors would be better located directly at the cartridge input, prior to the step-up transformer.
Best to keep the secondary load fixed at the rated 10k ohms, so connect a 12.7k resistor at the secondary output.
This combines with the 47k grid resistor to make the rated total of 10k.
Use loading resistors at the MC input, depending on the cartridge. Excessively low load
resistor values will reduce the cartridge output and increase noise. Load capacitance for MC is not needed.
Load capacitance is required for MM only, from 0pF to 500pF, depending on the cartridge.
Best to keep the secondary load fixed at the rated 10k ohms, so connect a 12.7k resistor at the secondary output.
This combines with the 47k grid resistor to make the rated total of 10k.
Use loading resistors at the MC input, depending on the cartridge. Excessively low load
resistor values will reduce the cartridge output and increase noise. Load capacitance for MC is not needed.
Load capacitance is required for MM only, from 0pF to 500pF, depending on the cartridge.
Hi, There is a MC phono amp on the Audio Karma site, that has variable loading from 40 to 100K built into the amp circuit. To do that where you would normally place the leading resistor in the circuit, Replace it with a variable resistor.
Cheers
Cheers
Is there some reason that you didn't post your questions to Bruce directly? He is more than happy to answer questions about any of his designs.
I have the same Lundahl transformer and SRPP tube input stage. My Denon DL-103 works fine with secondary loaded 47k. But if you go for 100R load, add another 47k parallel to the existing one. The measured transformation ratio is actually less than 16, it is rather 15.5. Important is to mount the transformer in a magnetically shielding box otherwise it picks up hum. I tell it from experience.
Thanks. I will make a mu-metal shield around it.
I want to make it a little bit universal, because I don't know what future bring. Therefore I wanted to use the jumpers.
I want to make it a little bit universal, because I don't know what future bring. Therefore I wanted to use the jumpers.
I did not know he was still around somewhere. I will try to find him.